Adjuvant platinum versus capecitabine for residual, invasive, triple-negative breast cancer: Patient-reported outcomes in ECOG-ACRIN EA1131

BACKGROUND

Patient-reported outcomes (PROs) are a better tool for evaluating the experiences of patients who have symptomatic, treatment-associated adverse events (AEs) compared with clinician-rated AEs. The authors present PROs assessing health-related quality of life (HRQoL) and treatment-related neurotoxicity for adjuvant capecitabine versus platinum on the Eastern Cooperative Oncology Group-American College of Radiology Imaging Network (ECOG-ACRIN) EA1131 trial (ClinicalTrials.gov identifier NCT02445391).

METHODS

Participants completed the National Comprehensive Cancer Network Functional Assessment of Cancer Therapy-Breast Cancer Symptom Index (NFBSI-16) and the Functional Assessment of Cancer Therapy-Gynecologic Oncology Group neurotoxicity subscale (platinum arm only) at baseline, cycle 3 day 1 (C3D1), 6 months, and 15 months. Because of early termination, power was insufficient to test the hypothesis that HRQoL, as assessed by the NFBSI-16 treatment side-effect (TSE) subscale, would be better at 6 and 15 months in the capecitabine arm; all analyses were exploratory. Means were compared by using t-tests or the Wilcoxon rank-sum test, and proportions were compared by using the χ2 test.

RESULTS

Two hundred ninety-six of 330 eligible patients provided PROs. The mean NFBSI-16 TSE subscale score was lower for the platinum arm at baseline (p = .02; absolute difference, 0.6 points) and for the capecitabine arm at C3D1 (p = .04; absolute difference, 0.5 points), but it did not differ at other times. The mean change in TSE subscale scores differed between the arms from baseline to C3D1 (platinum arm, 0.15; capecitabine arm, -0.72; p = .03), but not from baseline to later time points. The mean decline in Functional Assessment of Cancer Therapy-Gynecologic Oncology Group neurotoxicity subscale scores exceeded the minimal meaningful change (1.38 points) from baseline to each subsequent time point (all p < .05).

CONCLUSIONS

Despite the similar frequency of clinician-rated AEs, PROs identified greater on-treatment symptom burden with capecitabine and complemented clinician-rated AEs by characterizing patients' experiences during chemotherapy.

Feasibility and Tolerability of Adjuvant Capecitabine-Based Chemoradiation in Patients With Breast Cancer and Residual Disease After Neoadjuvant Chemotherapy: A Prospective Clinical Trial

PURPOSE

Addition of adjuvant capecitabine improves overall survival for patients with breast cancer lacking pathologic complete response to standard-of-care neoadjuvant chemotherapy. Combining radiosensitizing capecitabine concurrent with radiation may further improve disease control, although the feasibility and tolerability of chemoradiation in this setting is unknown. This study aimed to determine the feasibility of this combination. Secondary objectives included the effect of chemoradiation on physician-reported toxicity, patient-reported skin dermatitis, and patient-reported quality of life compared with patients with breast cancer treated with adjuvant radiation.

METHODS AND MATERIALS

Twenty patients with residual disease following standard neoadjuvant chemotherapy were enrolled in a prospective single-arm trial and treated with adjuvant capecitabine-based chemoradiation. Feasibility was defined as ≥75% of patients completing chemoradiation as planned. Toxicity was assessed using Common Terminology Criteria for Adverse Events version 5.0 and the patient-reported radiation-induced skin reaction scale. Quality of life was measured using the RAND Short-Form 36-Item Health Survey.

RESULTS

Eighteen patients (90%) completed chemoradiation without interruption or dose reduction. The incidence of grade ≥3 radiation dermatitis was 5% (1 of 20 patients). Patient-reported radiation dermatitis did not show a clinically meaningful difference following chemoradiation (mean increase, 55 points) compared with published reports of patients with breast cancer treated with adjuvant radiation alone (mean increase, 47 points). On the other hand, patient-reported quality of life demonstrated a clinically meaningful decline at the end of chemoradiation (mean, 46; SD, 7) compared with the reference population of patients treated with adjuvant radiation alone (mean, 50; SD, 6).

CONCLUSIONS

Adjuvant chemoradiation with capecitabine is feasible and tolerable in patients with breast cancer. Although current studies using adjuvant capecitabine for residual disease following neoadjuvant chemotherapy have specified sequential treatment of capecitabine and radiation, these results support the conduct of randomized trials in this setting to investigate the efficacy of concurrent radiation with capecitabine and provide patient-reported toxicity estimates for trial design.

The effect of neighborhood socioeconomic disadvantage on smoking status, quit attempts, and receipt of cessation support among adults with cancer: Results from nine ECOG-ACRIN Cancer Research Group trials

BACKGROUND

Tobacco use is associated with adverse outcomes among patients diagnosed with cancer. Socioeconomic determinants influence access and utilization of tobacco treatment; little is known about the relationship between neighborhood socioeconomic disadvantage (NSD) and tobacco assessment, assistance, and cessation among patients diagnosed with cancer.

METHODS

A modified Cancer Patient Tobacco Use Questionnaire (C-TUQ) was administered to patients enrolled in nine ECOG-ACRIN clinical trials. We examined associations of NSD with (1) smoking status, (2) receiving tobacco cessation assessment and support, and (3) cessation behaviors. NSD was classified by tertiles of the Area Deprivation Index. Associations between NSD and tobacco variables were evaluated using logistic regression.

RESULTS

A total of 740 patients completing the C-TUQ were 70% male, 94% White, 3% Hispanic, mean age 58.8 years. Cancer diagnoses included leukemia 263 (36%), lymphoma 141 (19%), prostate 131 (18%), breast 79 (11%), melanoma 69 (9%), myeloma 53 (7%), and head and neck 4 (0.5%). A total of 402 (54%) never smoked, 257 (35%) had formerly smoked, and 81 (11%) were currently smoking. Patients in high disadvantaged neighborhoods were approximately four times more likely to report current smoking (odds ratio [OR], 3.57; 95% CI, 1.69-7.54; p = .0009), and more likely to report being asked about smoking (OR, 4.24; 95% CI, 1.64-10.98; p = .0029), but less likely to report receiving counseling (OR, 0.11; 95% CI, 0.02-0.58; p = .0086) versus those in the least disadvantaged neighborhoods.

CONCLUSIONS

Greater neighborhood socioeconomic disadvantage was associated with smoking but less cessation support. Increased cessation support in cancer care is needed, particularly for patients from disadvantaged neighborhoods.

Effect of Metformin Versus Placebo on New Primary Cancers in Canadian Cancer Trials Group MA.32: A Secondary Analysis of a Phase III Randomized Double-Blind Trial in Early Breast Cancer

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned coprimary or secondary analyses are not yet available. Clinical trial updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.Metformin has been associated with lower cancer risk in epidemiologic and preclinical research. In the MA.32 randomized adjuvant breast cancer trial, metformin (v placebo) did not affect invasive disease-free or overall survival. Here, we report metformin effects on the risk of new cancer. Between 2010 and 2013, 3,649 patients with breast cancer younger than 75 years without diabetes with high-risk T1-3, N0-3 M0 breast cancer (any estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2) were randomly assigned to metformin 850 mg orally twice a day or placebo twice a day for 5 years. New primary invasive cancers (outside the ipsilateral breast) developing as a first event were identified. Time to events was described by the competing risks method; two-sided likelihood ratio tests adjusting for age, BMI, smoking, and alcohol intake were used to compare metformin versus placebo arms. A total of 184 patients developed new invasive cancers: 102 metformin and 82 placebo, hazard ratio (HR), 1.25; 95% CI, 0.94 to 1.68; P = .13. These included 48 contralateral invasive breast cancers (27 metformin v 21 placebo), HR, 1.29; 95% CI, 0.72 to 2.27; P = .40 and 136 new nonbreast primary cancers (75 metformin v 61 placebo), HR, 1.24; 95% CI, 0.88 to 1.74; P = .21. Metformin did not reduce the risk of new cancer development in these nondiabetic patients with breast cancer.

Cigarette and Alternative Tobacco Product Use among Adult Cancer Survivors Enrolled in 9 ECOG-ACRIN Clinical Trials

BACKGROUND

While cigarette smoking has declined among the U.S. general population, sale and use of non-cigarette alternative tobacco products (ATP; e.g., e-cigarettes, cigars) and dual use of cigarettes/ATPs are rising. Little is known about ATP use patterns in cancer survivors enrolled in clinical trials. We investigated prevalence of tobacco product use, and factors associated with past 30-day use, among patients with cancer in national trials.

METHODS

Cancer survivors (N = 756) enrolled in 9 ECOG-ACRIN clinical trials (2017-2021) completed a modified Cancer Patient Tobacco Use Questionnaire (C-TUQ) which assessed baseline cigarette and ATP use since cancer diagnosis and in the past 30 days.

RESULTS

Patients were on average 59 years old, 70% male, and the mean time since cancer diagnosis was 26 months. Since diagnosis, cigarettes (21%) were the most common tobacco product used, followed by smokeless tobacco use (5%), cigars (4%), and e-cigarettes (2%). In the past 30 days, 12% of patients reported smoking cigarettes, 4% cigars, 4% using smokeless tobacco, and 2% e-cigarettes. Since cancer diagnosis, 5.5% of the sample reported multiple tobacco product use, and 3.0% reported multiple product use in the past 30 days. Males (vs. females; OR 4.33; P = 0 < 0.01) and individuals not living with another person who smokes (vs. living with; OR, 8.07; P = 0 < 0.01) were more likely to use ATPs only versus cigarettes only in the past 30 days.

CONCLUSIONS

Among patients with cancer, cigarettes were the most prevalent tobacco product reported.

IMPACT

Regardless, ATPs and multiple tobacco product use should be routinely assessed in cancer care settings.

Endocrine Therapy Synergizes with SMAC Mimetics to Potentiate Antigen Presentation and Tumor Regression in Hormone Receptor-Positive Breast Cancer

Immunotherapies have yet to demonstrate significant efficacy in the treatment of hormone receptor-positive (HR+) breast cancer. Given that endocrine therapy (ET) is the primary approach for treating HR+ breast cancer, we investigated the effects of ET on the tumor immune microenvironment (TME) in HR+ breast cancer. Spatial proteomics of primary HR+ breast cancer samples obtained at baseline and after ET from patients enrolled in a neoadjuvant clinical trial (NCT02764541) indicated that ET upregulated β2-microglobulin and influenced the TME in a manner that promotes enhanced immunogenicity. To gain a deeper understanding of the underlying mechanisms, the intrinsic effects of ET on cancer cells were explored, which revealed that ET plays a crucial role in facilitating the chromatin binding of RelA, a key component of the NF-κB complex. Consequently, heightened NF-κB signaling enhanced the response to interferon-gamma, leading to the upregulation of β2-microglobulin and other antigen presentation-related genes. Further, modulation of NF-κB signaling using a SMAC mimetic in conjunction with ET augmented T-cell migration and enhanced MHC-I-specific T-cell-mediated cytotoxicity. Remarkably, the combination of ET and SMAC mimetics, which also blocks prosurvival effects of NF-κB signaling through the degradation of inhibitors of apoptosis proteins, elicited tumor regression through cell autonomous mechanisms, providing additional support for their combined use in HR+ breast cancer.

SIGNIFICANCE

Adding SMAC mimetics to endocrine therapy enhances tumor regression in a cell autonomous manner while increasing tumor immunogenicity, indicating that this combination could be an effective treatment for HR+ patients with breast cancer.

Evaluation of Alisertib Alone or Combined With Fulvestrant in Patients With Endocrine-Resistant Advanced Breast Cancer: The Phase 2 TBCRC041 Randomized Clinical Trial

Importance

Aurora A kinase (AURKA) activation, related in part to AURKA amplification and variants, is associated with downregulation of estrogen receptor (ER) α expression, endocrine resistance, and implicated in cyclin-dependent kinase 4/6 inhibitor (CDK 4/6i) resistance. Alisertib, a selective AURKA inhibitor, upregulates ERα and restores endocrine sensitivity in preclinical metastatic breast cancer (MBC) models. The safety and preliminary efficacy of alisertib was demonstrated in early-phase trials; however, its activity in CDK 4/6i-resistant MBC is unknown.

Objective

To assess the effect of adding fulvestrant to alisertib on objective tumor response rates (ORRs) in endocrine-resistant MBC.

Design, Setting, and Participants

This phase 2 randomized clinical trial was conducted through the Translational Breast Cancer Research Consortium, which enrolled participants from July 2017 to November 2019. Postmenopausal women with endocrine-resistant, ERBB2 (formerly HER2)-negative MBC who were previously treated with fulvestrant were eligible. Stratification factors included prior treatment with CDK 4/6i, baseline metastatic tumor ERα level measurement (<10%, ≥10%), and primary or secondary endocrine resistance. Among 114 preregistered patients, 96 (84.2%) registered and 91 (79.8%) were evaluable for the primary end point. Data analysis began after January 10, 2022.

Interventions

Alisertib, 50 mg, oral, daily on days 1 to 3, 8 to 10, and 15 to 17 of a 28-day cycle (arm 1) or alisertib same dose/schedule with standard-dose fulvestrant (arm 2).

Main Outcomes and Measures

Improvement in ORR in arm 2 of at least 20% greater than arm 1 when the expected ORR for arm 1 was 20%.

Results

All 91 evaluable patients (mean [SD] age, 58.5 [11.3] years; 1 American Indian/Alaskan Native [1.1%], 2 Asian [2.2%], 6 Black/African American [6.6%], 5 Hispanic [5.5%], and 79 [86.8%] White individuals; arm 1, 46 [50.5%]; arm 2, 45 [49.5%]) had received prior treatment with CDK 4/6i. The ORR was 19.6%; (90% CI, 10.6%-31.7%) for arm 1 and 20.0% (90% CI, 10.9%-32.3%) for arm 2. In arm 1, the 24-week clinical benefit rate and median progression-free survival time were 41.3% (90% CI, 29.0%-54.5%) and 5.6 months (95% CI, 3.9-10.0), respectively, and in arm 2 they were 28.9% (90% CI, 18.0%-42.0%) and 5.4 months (95% CI, 3.9-7.8), respectively. The most common grade 3 or higher adverse events attributed to alisertib were neutropenia (41.8%) and anemia (13.2%). Reasons for discontinuing treatment were disease progression (arm 1, 38 [82.6%]; arm 2, 31 [68.9%]) and toxic effects or refusal (arm 1, 5 [10.9%]; arm 2, 12 [26.7%]).

Conclusions and Relevance

This randomized clinical trial found that adding fulvestrant to treatment with alisertib did not increase ORR or PFS; however, promising clinical activity was observed with alisertib monotherapy among patients with endocrine-resistant and CDK 4/6i-resistant MBC. The overall safety profile was tolerable.

Trial Registration

ClinicalTrials.gov Identifier: NCT02860000.

FGFR1 Antibody Validation and Characterization of FGFR1 Protein Expression in ER+ Breast Cancer

Clinical trials in patients with ER+ breast cancer with or without FGFR pathway somatic alterations have shown limited clinical benefit from treatment with FGFR tyrosine kinase inhibitors alone or in combination with endocrine therapy. This is likely because of an inadequate predictive biomarker to select appropriate patients. In this study, we evaluated 4 anti-FGFR1 antibodies in breast cancer cell lines and patient-derived xenografts with FGFR1 amplification. We correlated D8E4 expression in 209 tumors from postmenopausal patients with stage I-III operable ER+ breast cancer with FGFR1 amplification status as determined by fluorescence in situ hybridization. FGFR1 amplification was identified in 10% of tumors (21/209), 80% of which exhibited membranous FGFR1 expression; however, only 50% of amplified cases showed strong, complete membranous staining (3+) based on established criteria to score HER2 by immunohistochemistry. These findings suggest the combined evaluation of FGFR1 status by immunohistochemistry and fluorescence in situ hybridization may need to be incorporated into the selection of patients for trials with FGFR inhibitors.

Neighborhood socioeconomic disadvantage, tobacco use, and cessation indicators among adults with cancer in the United States: Results from 10 ECOG-ACRIN trials

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Background: Tobacco use is a modifiable risk factor for adverse outcomes among patients diagnosed with cancer. Despite ASCO’s recommendation for assessment and treatment of tobacco use, integration into cancer care is suboptimal. Socioeconomic contexts influence access and utilization of tobacco treatment, but little is known about the relationship between neighborhood socioeconomic disadvantage (NSD) and tobacco assessment, assistance, and cessation among cancer patients enrolled in clinical trials. Methods: The NCI Cancer Patient Tobacco Use Questionnaire (C-TUQ) was centrally administered to participants enrolled in 10 ECOG ACRIN clinical trials (9 therapeutic, 1 imaging). We examined associations of NSD with patient-reported rates of receiving brief tobacco cessation support (i.e., Ask, Assist (counseling)) and cessation (past 30d quit attempts and duration). NSD was measured using the national Area Deprivation Index (ADI) based on participant’s zip code. Associations between ADI (low, intermediate, and high) and tobacco variables were evaluated using logistic regression and ANOVA. Results: 740 patients, completing the C-TUQ between June 2017-October 2021, can be classified as 402 (54%) never smokers, 81 (11%) current smokers, and 257 (35%) former smokers. Patients were 70% male; 94% white; 3% Hispanic; mean age 58.8 (SD 9.0). Cancer diagnoses were 36% leukemia; 19% lymphoma, 18% prostate, 11% breast; 9% melanoma, 7% myeloma, and 0.5% head and neck. Patients were categorized into high (33%), intermediate (34%) and low (33%) disadvantaged neighborhoods. Patients in high (vs. low) disadvantaged neighborhoods were more likely to report being asked about smoking (OR = 3.90; 95% CI (confidence interval), 1.61 to 9.46; p = 0.0062) but less likely to report receiving counseling to help quit smoking (OR = 0.20; 95% CI, 0.06 to 0.73; p = 0.0234). Patients from high disadvantaged neighborhoods had the shortest quit duration, followed by patients from intermediate and low disadvantaged neighborhoods (mean = 145.78, 187.66, and 210.98 months, respectively, p = 0.0372). Conclusions: Greater socioeconomic neighborhood disadvantage was associated with increased assessment of tobacco use but decreased tobacco treatment referral, and the shortest quit duration. More research is needed to promote increased referral to tobacco treatment for individuals with cancer from disadvantaged neighborhoods to promote and sustain cessation.

Effect of Metformin vs Placebo on Invasive Disease-Free Survival in Patients With Breast Cancer: The MA.32 Randomized Clinical Trial

Importance

Metformin, a biguanide commonly used to treat type 2 diabetes, has been associated with potential beneficial effects across breast cancer subtypes in observational and preclinical studies.

Objective

To determine whether the administration of adjuvant metformin (vs placebo) to patients with breast cancer without diabetes improves outcomes.

Design, Setting, and Participants

MA.32, a phase 3 randomized, placebo-controlled, double-blind trial, conducted in Canada, Switzerland, US, and UK, enrolled 3649 patients with high-risk nonmetastatic breast cancer receiving standard therapy between August 2010 and March 2013, with follow-up to October 2020.

Interventions

Patients were randomized (stratified for hormone receptor [estrogen receptor and/or progesterone receptor {ER/PgR}] status, positive vs negative; body mass index, ≤30 vs >30; human epidermal growth factor receptor 2 [ERBB2, formerly HER2 or HER2/neu], positive vs negative; and any vs no chemotherapy) to 850 mg of oral metformin twice a day (n = 1824) or oral placebo twice a day (n = 1825) for 5 years.

Main Outcomes and Measures

The primary outcome was invasive disease-free survival in hormone receptor-positive breast cancer. Of the 8 secondary outcomes, overall survival, distant relapse-free survival, and breast cancer-free interval were analyzed.

Results

Of the 3649 randomized patients (mean age, 52.4 years; 3643 women [99.8%]), all (100%) were included in analyses. After a second interim analysis, futility was declared for patients who were ER/PgR-, so the primary analysis was conducted for 2533 patients who were ER/PgR+. The median duration of follow-up in the ER/PgR+ group was 96.2 months (range, 0.2-121 months). Invasive disease-free survival events occurred in 465 patients who were ER/PgR+. The incidence rates for invasive disease-free survival events were 2.78 per 100 patient-years in the metformin group vs 2.74 per 100 patient-years in the placebo group (hazard ratio [HR], 1.01; 95% CI, 0.84-1.21; P = .93), and the incidence rates for death were 1.46 per 100 patient-years in the metformin group vs 1.32 per 100 patient-years in the placebo group (HR, 1.10; 95% CI, 0.86-1.41; P = .47). Among patients who were ER/PgR-, followed up for a median of 94.1 months, incidence of invasive disease-free survival events was 3.58 vs 3.60 per 100 patient-years, respectively (HR, 1.01; 95% CI, 0.79-1.30; P = .92). None of the 3 secondary outcomes analyzed in the ER/PgR+ group had statistically significant differences. Grade 3 nonhematological toxic events occurred more frequently in patients taking metformin than in patients taking placebo (21.5% vs 17.5%, respectively, P = .003). The most common grade 3 or higher adverse events in the metformin vs placebo groups were hypertension (2.4% vs 1.9%), irregular menses (1.5% vs 1.4%), and diarrhea (1.9% vs 7.0%).

Conclusions and Relevance

Among patients with high-risk operable breast cancer without diabetes, the addition of metformin vs placebo to standard breast cancer treatment did not significantly improve invasive disease-free survival.

Trial Registration

ClinicalTrials.gov Identifier: NCT01101438.

Peripheral Blood Monocyte Abundance Predicts Outcomes in Patients with Breast Cancer

Biomarkers of response are needed in breast cancer to stratify patients to appropriate therapies and avoid unnecessary toxicity. We used peripheral blood gene expression and cell type abundance to identify biomarkers of response and recurrence in neoadjuvant chemotherapy treated breast cancer patients. We identified a signature of interferon and complement response that was higher in the blood of patients with pathologic complete response. This signature was preferentially expressed by monocytes in single cell RNA sequencing. Monocytes are routinely measured clinically, enabling examination of clinically measured monocytes in multiple independent cohorts. We found that peripheral monocytes were higher in patients with good outcomes in four cohorts of breast cancer patients. Blood gene expression and cell type abundance biomarkers may be useful for prognostication in breast cancer.

Significance

Biomarkers are needed in breast cancer to identify patients at risk for recurrence. Blood is an attractive site for biomarker identification due to the relative ease of longitudinal sampling. Our study suggests that blood-based gene expression and cell type abundance biomarkers may have clinical utility in breast cancer.

Abstract GS4-10: Neratinib + fulvestrant + trastuzumab for hormone receptor-positive, HER2-mutant metastatic breast cancer and neratinib + trastuzumab for triple-negative disease: Latest updates from the SUMMIT trial

Background: HER2 mutations are oncogenic drivers in a subset of metastatic breast cancers (MBC). Neratinib (N) is an oral, irreversible pan-HER tyrosine kinase inhibitor with preclinical and clinical activity against HER2 mutations. Genomic analyses from paired biopsies following N ± fulvestrant (F) suggest that resistance to N may occur via amplification of the mutant allele or by acquisition of secondary HER2 mutations. Addition of trastuzumab (T) to N+F showed encouraging clinical activity with durable responses in the SUMMIT trial in hormone receptor-positive (HR+), HER2-mutant MBC, including patients (pts) who had previously received cyclin-dependent kinase 4 & 6 inhibitors (CDK4/6i) [Jhaveri et al. SABCS 2020]. On the basis of these findings, and in order to better understand the contribution of N to the activity of the N+F+T combination, SUMMIT has recently been expanded to include a randomized Simon 2-stage comparison of N+F+T vs. F+T vs. F in pts with HR+, HER2-mutated, HER2-negative MBC who were exposed to CDK4/6i. Enrollment for stage 1 is now complete (N+F+T, n=7; F+T, n=7; F, n=7), and results will be forthcoming once the data are mature. Here we report updated findings from the breast cancer cohorts of the SUMMIT trial for which data are currently available. Methods: The phase 2 SUMMIT trial (NCT01953926) enrolled pts with HR+, HER2-negative MBC whose tumors harbored activating HER2 mutation(s) identified by genomic sequencing. Prior to starting the randomized portion of the trial, these patients were enrolled in a non-randomized cohort and received N+F+T (oral N 240 mg/d, i.m. F 500 mg d1&15 of cycle 1 then q4w, i.v. T 8 mg/kg initially then 6 mg/kg q3w). Following initiation of the randomized portion of the trial, these pts received N+F+T, F+T or F (1:1:1 ratio; dose schedules as above). Pts with HER2-mutant triple-negative breast cancer (TNBC) were enrolled in a non-randomized cohort and received N+T (dose schedules as above). Loperamide prophylaxis was mandatory during the first 2 treatment cycles. There was no restriction on the number of prior lines of systemic therapy for MBC. Efficacy endpoints: investigator-assessed objective response rate and clinical benefit rate (RECIST v1.1 or other defined criteria); duration of response; best overall response. Results: Prior to enrolling the randomized cohort, 24 pts with HR+, HER2-mutated MBC who had previously received CDK4/6i were enrolled in the non-randomized cohort and received N+F+T, and 17 pts with HER2-mutant TNBC were enrolled and received N+T, as of 18-Jun-2021. Data for randomized pts are not yet mature. HER2 allelic variants across both cohorts (pts may have &gt;1 mutation): kinase domain hotspots (n=26); exon-20 insertion (n=9); extracellular domain hotspot (n=4); exon-19 deletion (n=1); transmembrane domain missense (n=1); kinase domain non-hotspot (n=2). Efficacy findings are reported in the Table. Diarrhea was the most commonly reported adverse event: N+F+T (non-randomized cohort), 96%; N+T (TNBC cohort), 94%. No grade 4 diarrhea was reported.

Conclusions: N+F+T is a promising combination for pts with HR+, HER2-mutated MBC with prior exposure to CDK4/6 inhibitors. N+T also showed encouraging activity in HER2-mutated TNBC. The first results from the randomized comparison of N+F+T vs. F+T vs. F in pts with HR+, HER2-mutated MBC (Simon stage 1 analysis) will be presented at the meeting.

Table: Efficacy findingsHR+, HER2-mutated, HER2-non-amplified MBCHER2-mutant TNBCN+F+T (n=24)N+T (n=17)Confirmed objective response,a n (%)11 (46)5 (29)CR0 (0)1 (6)PR11 (46)4 (24)ORR, % (95% CI)46 (26–67)29 (10–56)Best overall response, n (%)13 (54)7 (41)CR0 (0)1 (6)PR13 (54)6 (35)Best overall response rate, % (95% CI)54 (33–74)41 (18–67)Medianb DOR, months (95% CI)14.4 (6.4–NR)NRClinical benefit, n (%)14 (58)6 (35)CR or PR11 (46)5 (29)SD ≥24 weeks3 (13)1 (6)CBR,b % (95% CI)58 (37–78)35 (14–62)aORR defined as either a CR or PR confirmed no less than 4 weeks after the response criteria are met; bCBR defined as confirmed CR or PR or SD for ≥24 weeks. Note: Tumor response is based on investigator tumor assessments per RECIST v1.1 for HR+, HER2-mutated cohort, and RECIST v1.1 or modified PERCIST for HER2-mutated TNBC cohort. CBR, clinical benefit rate; CI, confidence interval; CR, complete response; DOR, duration of response; F, fulvestrant; HR+, hormone receptor-positive; MBC, metastatic breast cancer; N, neratinib; NR, not reached; ORR, objective response rate; PERCIST, Positron Emission Tomography Response Criteria in Solid Tumors; PR, partial response; RECIST, Response Evaluation Criteria in Solid Tumors; SD, stable disease; T, trastuzumab, TNBC, triple-negative breast cancer.

Citation Format: Komal Jhaveri, Haeseong Park, James Waisman, Jonathan W Goldman, Angel Guerrero-Zotano, Valentina Boni, Barbara Haley, Ingrid A Mayer, Adam Brufsky, Eddy S Yang, José A García-Sáenz, François-Clement Bidard, John Crown, Bo Zhang, Aimee Frazier, Irmina Diala, Lisa D Eli, Brian Barnett, Hans Wildiers. Neratinib + fulvestrant + trastuzumab for hormone receptor-positive, HER2-mutant metastatic breast cancer and neratinib + trastuzumab for triple-negative disease: Latest updates from the SUMMIT trial [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr GS4-10.

Abstract P3-14-11: Mammaprint and Blueprint identify genomic differences in HR+ HER2- breast cancers from young Black and White women

Introduction: Hormone receptor positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) breast cancer, the most common immunohistochemical subtype, remains the dominant contributor to annual breast cancer deaths worldwide across all racial and ethnic groups. Black women are 41% more likely to die from breast cancer compared to White women, predominantly among women diagnosed ≤ 50 years of age. Yet, Black women remain underrepresented in clinical trials and population-based studies. Thus, it is critical to better characterize tumor molecular features from young Black women to identify factors contributing to the existing racial survival disparity. In the current study, we compared risk of distant recurrence signature, MammaPrint (MP), molecular subtyping signature, BluePrint (BP), and whole transcriptome differences between young Black women with HR+ HER2- breast cancer compared to matched White controls. Methods: This study included 156 Black women aged ≤ 50 with stage I-III, HR+ HER2- breast cancer of whom, 68 were recruited from 2009-2014 as part of the BEST study (5R01CA204819-04) with follow-up data available (median 114.5 months). The remaining 88 Black women were enrolled in the ongoing FLEX Study (NCT03053193) from 2017. White women (n=156) were randomly selected from FLEX and matched by age, tumor stage, and receptor status. Tumors were classified through MP as Low Risk (MP-LR) versus High Risk (MP-HR), with MP-HR further stratified into HR1 and HR2; HR2 tumors exhibit superior chemosensitivity as demonstrated in a prior large clinical trial of breast cancer patients (ISPY2). All women had MP and BP to classify tumors as Luminal A (MP-LR), Luminal B (MP-HR), HER2, or Basal, and full transcriptomic analyses. Differential gene expression analysis was performed with R package ‘limma’ to compare Black and White women and further compare within each molecular subtype. Differentially expressed genes (DEGs) with a false discovery rate &lt;0.05 were significant. Results: Of 312 young women with localized, HR+ HER2- breast cancer, high grade tumors were more frequent among Black compared to White women (34.6% vs 25.6%; p=0.08). MP-HR tumors were significantly more frequent among Black compared to White women (67.3% vs. 50.0%; p=0.002). Among MP-HR tumors, more HR2 tumors were seen in Black (25.6%) compared to White women (14.1%). Among women with MP-HR tumors and known treatment information, most Black women (94.3%) and all White women received chemotherapy. There were more Luminal B tumors in Black compared to White women (51.9% vs. 41.7%; p=0.07). BP reclassified a larger proportion of ER+ tumors as Basal in Black compared to White women (14.1% vs. 8.3%). Of 68 Black women with available survival data, 7 had death and/or distant recurrence events, of whom 6 (85.7%) had MP-HR tumors (4 Luminal B, 1 HER2, and 1 Basal) and 1 had MP-LR Luminal A tumor. Compared to White women, Black women with: 1) Luminal B tumors had 192 DEGs with upregulation of suspected poor prognosis genes, PSPH and IGHG1; 2) Luminal A tumors had upregulation of PSPH; and 3) Basal tumors had downregulation of POTEH. Conclusion: Among young women with localized HR+ HER2- breast cancer, MP and BP molecular signatures more robustly identified racial disparities in risk and subtype distribution beyond that identified through clinical factors adjusted for age and tumor characteristics. The transcriptomic differences among Black compared to White women across all BP subtypes provide novel insights about tumor biological differences. These findings have tremendous translational potential to identify etiologic underpinnings of racial survival disparities which may guide therapeutic strategies to improve outcomes.

Citation Format: Sonya Reid, Tuya Pal, Ingrid A. Mayer, Xiao-Ou Shu, Ann L. Tezak, Kent Hoskins, Dipali Sharma, Patricia Robinson, Jennifer Wei, Jake Ruby, Shiyu Wang, Josien Haan, Andrea Menicucci, William Audeh, FLEX Investigators Group. Mammaprint and Blueprint identify genomic differences in HR+ HER2- breast cancers from young Black and White women [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-14-11.

Abstract GS1-08: CCTGMA.32, a phase III randomized double-blind placebo controlled adjuvant trial of metformin (MET) vs placebo (PLAC) in early breast cancer (BC): Results of the primary efficacy analysis (clinical trials.gov NCT01101438)

Background: MET has been associated with beneficial anti-cancer effects in epidemiologic and preclinical research. It may act indirectly by reversing obesity associated physiologic changes or directly via mitochondrial mediated effects on LKB1/AMPK/mTOR and other mechanisms. MA.32 investigated the effect of MET vs PLAC (in addition to standard therapy) on adjuvant BC outcomes. Design: Randomized, placebo-controlled double-blind Phase III clinical trial conducted within the NCI US National Clinical Trials Network, NCRI (UK) BG, IBCSG. Methods: Between 2010-2013 BC patients &lt; 75 yo without diabetes (DM) with high risk T1-3, N0-3 M0 BC regardless of ER, PgR, HER2 and with adequate cardiac, renal and hepatic function were randomized (stratified for ER/PgR + vs -, BMI &lt; vs &gt; 30 kg/m2, HER2 +ve vs -ve, any vs no chemo) within 1 year of BC diagnosis to MET 850 mg po bid or PLAC bid for 5 years. Dose was reduced for toxicity with re-escalation when possible. Subjects were followed for Invasive Disease-Free Survival (IDFS primary outcome; events included invasive local/regional recurrences, distant recurrences, new ipsilateral/contralateral invasive BCs, new non-breast primary cancers, any death), Overall Survival (OS), Distant Relapse Free Survival (DRFS), BC Specific Survival (BCSS), BC Free Interval (BCFI), contralateral BC and cardiovascular (CV) events/new DM. 3582 subjects were required for 80% power to detect HR 0.76 (431 events). In 2011, entry was restricted to higher risk BC, leading to 80% power to detect HR 0.785 (544 events). In 2016, after the 2nd interim analysis at 29.5 months median F/U, the DSMB recommended (i) the intervention be continued with primary analysis triggered at 544 events be conducted in ER/PgR +ve (any HER2) subjects only and (ii) ER/PgR -ve subjects stop study drug for futility but blinding and follow-up continue. In 2021, a time driven analysis in ER/PgR +ve BC was approved (465 events providing 80% power to detect the original HR 0.76). Time to event survival described by the Kaplan-Meier method. Two-sided log-rank tests adjusting for stratification factors were primarily used to compare IDFS between arms. Cox proportional hazards models were used to identify and adjust for factors significantly related to IDFS. Results: 3649 subjects were enrolled. In the 2533 ER/PgR +ve subjects included in the primary analysis, baseline mean (± SD) age was 52.7 (±9.9 yrs); mean BMI 28.8 (±6.4) kg/m2. Baseline tumor characteristics were balanced: T stage 1/2/3/4 = 832/1351/349/1; N stage 0/1/2/3 = 964/1097/449/23; HER2+ 429. 1901 (75%) received XRT. 2150 (84.9%) received (neo)adj chemo, 2223 (87.8%) (neo)adj hormones and 434 (17.1%) HER2 targeted therapy. Any Grade ≥ 3 toxicity was similar in MET and PLAC arms (21.7% and 18.7%, P = 0.06). Median follow-up was 96.2 (range 0.2-121.0) months with 465 IDFS events (234 MET, 231 PLAC, 76% due to BC). Efficacy results are shown below.

MET vs PLACMET vs PLACIDFSOSPopulation Included# subjectsHR (95% CI)HR (95% CI)PRIMARY ANALYSISER/PgR +ve (any HER2)*25331.01 (0.84-1.21). P=0.920.89 (0.64-1.23). P=0.46ER/PgR -ve (any HER211161.01 (0.79-1.30. P=0.92)0.89 (0.64-1.23). P=0.46Exploratory. AnalysisHER2 +ve (any ER/PgR)6200.64 (0.43-0.95. P=0.0260.53 (0.30-0.98. P=0.0398**in ER/PgR pos BC HRs were similar for BCFI, DRFS, BCSS (ranging from 0.98-1.09)Conclusions: MET did not improve IDFS or other BC outcomes in ER/PgR positive or ER/PgR negative BC and should not be used as adjuvant treatment. Exploratory findings suggesting benefit in HER2+ve BC should be further investigated. Funded by: CCSRI, NCI (US), CBCF, BCRF, CRUK, Hold’Em for Life Charity, Apotex (Canada)

Citation Format: Pamela J. Goodwin, Bingshu E Chen, Karen A Gelmon, Timothy J Whelan, Marguerite Ennis, Julie Lemieux, Jennifer A Ligibel, Dawn L Hershman, Ingrid A Mayer, Timothy J Hobday, Judith M Bliss, Priya Rastogi, Manuela Rabaglio-Poretti, Som D. Mukherjee, Robert R Mackey, Vandana G Abramson, Conrad Oja, Robert Wesolowski, Alastair M Thompson, Daniel W Rea, Paul M Stos, Lois E Shepherd, Vuk Stambolic, Wendy R Parulekar. CCTGMA.32, a phase III randomized double-blind placebo controlled adjuvant trial of metformin (MET) vs placebo (PLAC) in early breast cancer (BC): Results of the primary efficacy analysis (clinical trials.gov NCT01101438) [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr GS1-08.

Abstract P4-10-02: Patient-reported outcomes in EA1131: A randomized phase III trial of platinum vs. capecitabine in patients with residual triple-negative breast cancer after neoadjuvant chemotherapy

Background: Understanding health-related quality of life (HRQOL), including side effects, is critical to guide supportive care during chemotherapy. The EA1131 trial demonstrated that Platinum (Plat) was unlikely to improve outcomes compared to capecitabine (Cape) in patients with stage II-III triple-negative breast cancer (TNBC) of basal subtype and ≥1 cm residual disease after neoadjuvant chemotherapy (NAC), supporting Cape as the continued standard of care. Patient-reported outcomes (PRO) were administered as a sub-study to understand HRQOL and symptoms from the patient’s perspective. Methods: EA1131 was amended in 9/2017 to add PRO endpoints and all patients enrolled after this amendment were eligible for the PRO sub-study. The Functional Assessment of Cancer Therapy-Breast Cancer Symptom Index (FBSI) and the Functional Assessment of Cancer Therapy/Gynecologic Oncology Group Neurotoxicity Subscale (NtxS; Plat arm only) were administered at baseline (BL), cycle 3 day 1 (C3D1), and following treatment at 6 and 15 months. Due to early trial termination, the PRO sub-study target accrual (n=362) was not reached. It was hypothesized that HRQOL, assessed by the FBSI-Treatment Side Effect (TSE) subscale (range 0-16, higher score = less side effects, better HRQOL), would indicate fewer post-treatment side effects at 6 and 15 months following Plat compared to Cape. The Wilcoxon rank sum test was used to compare FBSI-TSE subscale scores and total FBSI scores (range 0-64, higher score = better overall HRQOL) between arms at BL, C3D1, 6 months and 15 months. Two-sample t-tests were used to compare change in FBSI-TSE subscale scores and total FBSI scores from BL to C3D1 between arms. Change in NtxS scores (range 0-44, higher score = less neurotoxicity) from BL to C3D1 was evaluated with the paired t-test. Analyses were exploratory and p-values &lt;0.05 considered significant without multiple comparisons adjustment. Results: Of 331 patients eligible for the PRO sub-study (156 Plat arm, 175 Cape arm), 296 (89.4%) completed ≥1 PRO. Mean FBSI-TSE subscale scores were better for Cape at BL (Cape 14.5, Plat 13.9, p-value 0.02), for Plat at C3D1 (Cape 13.5, Plat 14.0, p-value 0.04), and did not differ at 6 months (Cape 14.6, Plat 14.7, p-value 0.70) or 15 months (Cape 14.9, Plat 14.5, p-value 0.44). FBSI-TSE subscale scores worsened from BL to C3D1 for Cape but not for Plat (mean change Cape -0.72, mean change Plat 0.15, p-value 0.003). FBSI-TSE subscale change scores from BL to C3D1 exceeded the threshold for clinically meaningful worsening (&gt; 1.5 points) in 27% of patients on Cape and 23% of patients on Plat (p-value 0.51). Mean total FBSI scores did not differ between arms at any time (BL: Cape 50.6, Plat 49.7; C3D1: Cape 48.1, Plat 48.0; 6 months: Cape 49.9, Plat 51.1; 15 months: Cape 53.3, Plat 50.3; all p &gt; 0.05). Mean change in total FBSI scores from BL to C3D1 did not differ between arms (Cape -2.20, Plat -1.83, p = 0.75). Mean (standard deviation) NtxS scores for the Plat arm were 38 (6.3), 36.1 (7.8), 36 (7.1) and 34.5 (7.9) at BL, C3D1, 6 months and 15 months, respectively. Mean NtxS score decreased (indicating worsening neurotoxicity) from BL to C3D1 (p-value 0.006). Conclusions: Despite more frequent severe toxicity by CTCAE criteria for Plat than Cape, patient-reported side effects worsened during treatment with Cape but not Plat. Overall, changes in HRQOL were small for both arms and resolved after therapy. However approximately one-fourth of patients had clinically meaningful worsening side effects on both arms. PRO-assessed neurotoxicity increased in the Plat arm. This PRO sub-study demonstrates that PROs capture toxicities beyond CTCAE criteria and provides novel data about patients’ experience during adjuvant chemotherapy following NAC for TNBC.

Citation Format: Karen L Smith, Fengmin Zhao, Ingrid A Mayer, Amye J Tevaarwerk, Sofia F Garcia, Carlos L Arteaga, William F Symmans, Ben H Park, Brian L Burnette, Della F Makower, Margaret Block, Kimberly A Morley, Chirag R Jani, Craig Mescher, Shabana J Dewani, Ursa Brown-Glaberman, Lisa E Flaum, Erica L Mayer, William M Sikov, Eve T Rodler, Angela M DeMichele, Joseph A Sparano, Antonio C Wolff, Kathy D Miller, Lynne I Wagner. Patient-reported outcomes in EA1131: A randomized phase III trial of platinum vs. capecitabine in patients with residual triple-negative breast cancer after neoadjuvant chemotherapy [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-10-02.

Abstract GS1-07: Adjuvant palbociclib in HR+/HER2- early breast cancer: Final results from 5,760 patients in the randomized phase III PALLAS trial

Background Advances in the multidisciplinary care of hormone-receptor positive (HR+) early breast cancer (eBC) have markedly improved clinical outcomes: however, disease recurrence may still occur, particularly in patients (pts) with moderate or high-risk cancers at the time of diagnosis. The use of CDK4/6 inhibitors (CDK4/6i) combined with endocrine therapy (ET) is a standard of care for advanced breast cancer, supporting the rationale to study CDK4/6i in the eBC setting. Here we present the final protocol-planned analyses of the global phase III PALLAS trial investigating whether the addition of the CDK4/6i palbociclib (P) to adjuvant ET improves outcomes over ET alone for HR+/HER2- eBC. Methods PALLAS (PALbociclib CoLlaborative Adjuvant Study, NCT02513394) is a randomized phase III open-label trial in which pts with stage II-III HR+/HER2- eBC were randomized to receive either 2 years of P with adjuvant ET (P+ET) or ET alone. The primary endpoint is invasive disease-free survival (iDFS); secondary endpoints include distant recurrence-free survival (DRFS), locoregional recurrence-free survival (LRRFS), overall survival (OS), and safety. Mandatory biospecimen collection has supported the creation of an expansive translational science program, and long-term follow-up is planned. Revised sample size calculations required recruitment of 5600 pts in order to detect a 25% iDFS improvement in patients receiving P+ET with 85% power; this final protocol-planned analysis was planned after 469 iDFS events. Results From September 1, 2015 to November 30, 2018, 5,761 pts (median age 52 years, range 22-90) were randomized in 406 centers in 21 countries worldwide. 1,014 (17.6%) had stage IIA disease (capped) and 4,728 (82.1%) stages IIB/III. 4,754 (82.5%) had received prior (neo)adjuvant chemotherapy. After a protocol-planned 2nd interim analysis in May 2020 crossed the futility threshold, 349 P+ET pts still on active treatment stopped P and were transferred to follow-up. At the time of final analysis cutoff date (November 20, 2020), after a median follow-up of 31 months and 516 events recorded, iDFS was similar between the two arms, with 3-year iDFS of 89.3% (95% CI: 87.8-90.6%) for Palbo+ET, and 89.4% (88.0-90.7%) for ET alone (hazard ratio 0.96, 95% CI: 0.81-1.14). There was no statistically significant difference in secondary outcome endpoints. Subgroup analyses revealed no significant interactions between treatment effect and other factors (including risk category). The safety profile of P was as expected, with grade 3 or 4 neutropenia the most common side effect (safety population: 1759/2841 [61.9%] vs 11/2902 [0.4%]). Overall 42% of pts. discontinued P prior to the planned 2-year duration, 28.2% of Palbo+ET pts discontinued therapy due to adverse events, without an observed impact on survival outcomes. Conclusions Now with the full number of events, this analysis of the PALLAS trial shows that the addition of 2 years of P to ongoing adjuvant ET did not improve survival endpoints for pts with stage II-III HR+/HER2- eBC. Whether P is beneficial in the adjuvant setting for certain sub-groups of pts will be further evaluated with longer-term follow-up and by the ongoing translational science program. Support: ABCSG; AFT; Pfizer; ClinicalTrials.gov Identifier: NCT02513394; https://www.abcsg.org; https://acknowledgments.alliancefound.org

Citation Format: Michael Gnant, Amylou C Dueck, Sophie Frantal, Miguel Martin, Hal Burstein, Richard Greil, Peter Fox, Antonio C Wolff, Arlene Chan, Eric Winer, Christian Singer, Kathy Miller, Marco Colleoni, Michelle Naughton, Gabor Rubovszky, Judith Bliss, Ingrid A Mayer, Guenther G Steger, Zbigniew Nowecki, Olwen Hahn, Norman Wolmark, Hope Rugo, Georg Pfeiler, Hannes Fohler, Otto Metzger, Céline Schurmans, Kathy P Theall, Dongrui R Lu, Kathleen Tenner, Christian Fesl, Angela DeMichele*, Erica L Mayer, *shared last authorship. Adjuvant palbociclib in HR+/HER2- early breast cancer: Final results from 5,760 patients in the randomized phase III PALLAS trial [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr GS1-07.

Treatment Exposure and Discontinuation in the PALbociclib CoLlaborative Adjuvant Study of Palbociclib With Adjuvant Endocrine Therapy for Hormone Receptor-Positive/Human Epidermal Growth Factor Receptor 2-Negative Early Breast Cancer (PALLAS/AFT-05/ABCSG-42/BIG-14-03)

PURPOSE

The PALLAS study investigated whether the addition of palbociclib, an oral CDK4/6 inhibitor, to adjuvant endocrine therapy (ET) improves invasive disease-free survival (iDFS) in early hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) breast cancer. In this analysis, we evaluated palbociclib exposure and discontinuation in PALLAS.

METHODS

Patients with stage II-III HR+, HER2- disease were randomly assigned to 2 years of palbociclib with adjuvant ET versus ET alone. The primary objective was to compare iDFS between arms. Continuous monitoring of toxicity, dose modifications, and early discontinuation was performed. Association of baseline covariates with time to palbociclib reduction and discontinuation was analyzed with multivariable competing risk models. Landmark and inverse probability weighted per-protocol analyses were performed to assess the impact of drug persistence and exposure on iDFS.

RESULTS

Of the 5,743 patient analysis population (2,840 initiating palbociclib), 1,199 (42.2%) stopped palbociclib before 2 years, the majority (772, 27.2%) for adverse effects, most commonly neutropenia and fatigue. Discontinuation of ET did not differ between arms. Discontinuations for non-protocol-defined reasons were greater in the first 3 months of palbociclib, and in the first calendar year of accrual, and declined over time. No significant relationship was seen between longer palbociclib duration or ≥ 70% exposure intensity and improved iDFS. In the weighted per-protocol analysis, no improvement in iDFS was observed in patients receiving palbociclib versus not (hazard ratio 0.89; 95% CI, 0.72 to 1.11).

CONCLUSION

Despite observed rates of discontinuation in PALLAS, analyses suggest that the lack of significant iDFS difference between arms was not directly related to inadequate palbociclib exposure. However, the discontinuation rate illustrates the challenge of introducing novel adjuvant treatments, and the need for interventions to improve persistence with oral cancer therapies.

A Phase Ib Dose Escalation Trial of RO4929097 (a γ-secretase inhibitor) in Combination with Exemestane in Patients with ER + Metastatic Breast Cancer (MBC)

PRECLINICAL STUDIES: have demonstrated a complex cross-talk between Notch and estrogen signaling in ERα-positive breast cancer. Gamma-secretase inhibitors (GSIs) are investigational agents that block the cleavage and activation of Notch receptors. In animal models of endocrine-resistant breast cancer, combinations of tamoxifen and GSIs produce additive or synergistic efficacy, while decreasing the intestinal toxicity of GSIs. However, results of a clinical trial of a GSI-endocrine therapy combination in the metastatic setting have not been published to date, nor had the safety of such combinations been investigated with longer term treatment. We conducted a phase 1b dose escalation trial (NCT01149356) of GSI RO4929097 with exemestane in patients with ERα+, metastatic breast cancer (MBC) STUDY OBJECTIVES: To determine the safety, tolerability and maximum tolerated dose (MTD) or recommended phase 2 dose (RP2D) of RO4929097 when administered in combination with exemestane in patients with estrogen receptor positive metastatic breast cancer RESULTS: We enrolled 15 patients with MBC. Of 14 evaluable patients, one had a partial response, 6 had stable disease and 7 progressive disease. Twenty % of patients had stable disease for ≥ 6 months. Common toxicities included nausea (73.3%), anorexia (60%), hyperglycemia (53.3%), hypophosphatemia (46.7%), fatigue (66.7%) and cough (33.0%). Grade 3 toxicities were uncommon, and included hypophosphatemia (13%) and rash (6.3%). Rash was the only DLT observed at 140 mg/d. Results suggest a possible recommended phase 2 dose of 90 mg/d. Ten patients with evaluable archival tissue showed expression of PKCα, which correlated with expression of Notch4. Mammospheres from a PKCα-expressing, endocrine-resistant T47D cell line were inhibited by a GSI-fulvestrant combination CONCLUSIONS: Our data indicate that combinations including endocrine therapy and Notch inhibitors deserve further investigation in endocrine-resistant ERα-positive breast cancer.

Adjuvant Palbociclib for Early Breast Cancer: The PALLAS Trial Results (ABCSG-42/AFT-05/BIG-14-03)

PURPOSE

Palbociclib is a cyclin-dependent kinase 4 and 6 inhibitor approved for advanced breast cancer. In the adjuvant setting, the potential value of adding palbociclib to endocrine therapy for hormone receptor-positive breast cancer has not been confirmed.

PATIENTS AND METHODS

In the prospective, randomized, phase III PALLAS trial, patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative early breast cancer were randomly assigned to receive 2 years of palbociclib (125 mg orally once daily, days 1-21 of a 28-day cycle) with adjuvant endocrine therapy or adjuvant endocrine therapy alone (for at least 5 years). The primary end point of the study was invasive disease-free survival (iDFS); secondary end points were invasive breast cancer-free survival, distant recurrence-free survival, locoregional cancer-free survival, and overall survival.

RESULTS

Among 5,796 patients enrolled at 406 centers in 21 countries worldwide over 3 years, 5,761 were included in the intention-to-treat population. At the final protocol-defined analysis, at a median follow-up of 31 months, iDFS events occurred in 253 of 2,884 (8.8%) patients who received palbociclib plus endocrine therapy and in 263 of 2,877 (9.1%) patients who received endocrine therapy alone, with similar results between the two treatment groups (iDFS at 4 years: 84.2% v 84.5%; hazard ratio, 0.96; CI, 0.81 to 1.14; P = .65). No significant differences were observed for secondary time-to-event end points, and subgroup analyses did not show any differences by subgroup. There were no new safety signals for palbociclib in this trial.

CONCLUSION

At this final analysis of the PALLAS trial, the addition of adjuvant palbociclib to standard endocrine therapy did not improve outcomes over endocrine therapy alone in patients with early hormone receptor-positive breast cancer.

Abstract LBA003: Erdafitinib in patients with tumors harboring FGFR gene mutations or fusions: Results from the NCI-MATCH ECOG-ACRIN Trial (EAY131) Sub-protocol K2

Background: The NCI-MATCH precision medicine trial assigns patients (pts) with solid tumors, lymphoma, or multiple myeloma whose cancers have progressed on prior treatment to a targeted therapy based on genetic alterations identified in pre-treatment biopsies. Arm K2 (EAY131-K2) evaluated the pan-FGFR inhibitor erdafitinib (E) in pts with FGFR mutations or fusions. Patients and methods: Pts with bladder or urothelial cancers were excluded. Pts received E 8 mg PO daily (28-day cycle) until disease progression or unacceptable toxicity; dose reduction for toxicities was allowed; imaging was performed every 2 cycles. The primary endpoint was objective response rate (ORR); secondary endpoints included progression-free survival (PFS), 6-month PFS, and overall survival (OS). Results: A total of 35 pts were enrolled to this arm from 07/2018-07/2019; one was ineligible and one did not receive treatment. Nine distinct tumor histologies were represented, most common being pancreatobiliary (11), CNS (7) and gynecological tumors (5). 73% of pts were female, with median age of 59y (range 26-83y), 70% were Caucasian, and 61% of pts had received at least 3 prior therapies (range 0-22). Alterations in FGFR1, FGFR2 and FGFR3 were recorded in 6, 18, and 9 evaluable pts, respectively. 18 pt tumors had fusions and 15 had mutations in an FGFR gene. The confirmed ORR was 12% (90% CI 4%, 26%), with a median duration of response (DoR) of 7.3 months (mo), range 4.2-11.7 mo. Responses were seen in cholangiocarcinoma (2 pts), Brenner ovarian tumor and adenoid cystic carcinoma (1 pt each). Two (50%) of these 4 tumors harbored FGFR fusions and 2 FGFR mutations. 13 pts had stable disease (SD). Median PFS was 3.9 mo, and 6-mo PFS was 32.8% (90% CI 21.2%, 50.6%). Median OS was 11.0 mo. Of the 6 pts with intrahepatic cholangiocarcinoma, 2 had PR and 2 SD. The most frequent grade 3 treatment-related AEs were oral mucositis/pain (5 pts), paronychia, electrolyte disorders, and anemia/lymphopenia (2 pts each). There were no treatment-related grade 4-5 toxicities. Toxicities were reversible and manageable with E dose interruptions and/or dose reduction. Conclusions: In this pre-treated, mixed histology cohort with tumors harboring FGFR somatic alterations, E showed activity with durable responses and disease stabilizations outside of currently approved FDA indications, although the pre-specified criterion that the primary endpoint, ORR, be significantly greater than 16% was not reached. Toxicities were consistent with E safety profile. Responses were observed in tumors harboring FGFR fusions as well as in those with mutations of FGFR; further correlative analyses are planned.

Citation Format: Alain C Mita, Zihan Wei, Ingrid A Mayer, Heather Cheng, Edith P Mitchell, John J Wright, Percy Ivy, Robert J Gray, Victoria Wang, Lisa M McShane, Larry V Rubinstein, David R Patton, Mickey Williams, Stanley R Hamilton, Barbara A Conley, Carlos L Arteaga, Lyndsay N Harris, Peter J O'Dwyer, Alice P Chen, Keith T Flaherty. Erdafitinib in patients with tumors harboring FGFR gene mutations or fusions: Results from the NCI-MATCH ECOG-ACRIN Trial (EAY131) Sub-protocol K2 [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr LBA003.

Impact of HER2 Heterogeneity on Treatment Response of Early-Stage HER2-Positive Breast Cancer: Phase II Neoadjuvant Clinical Trial of T-DM1 Combined with Pertuzumab

Intratumor heterogeneity is postulated to cause therapeutic resistance. To prospectively assess the impact of HER2 (ERBB2) heterogeneity on response to HER2-targeted therapy, we treated 164 patients with centrally confirmed HER2-positive early-stage breast cancer with neoadjuvant trastuzumab emtansine plus pertuzumab. HER2 heterogeneity was assessed on pretreatment biopsies from two locations of each tumor. HER2 heterogeneity, defined as an area with ERBB2 amplification in >5% but <50% of tumor cells, or a HER2-negative area by FISH, was detected in 10% (16/157) of evaluable cases. The pathologic complete response rate was 55% in the nonheterogeneous subgroup and 0% in the heterogeneous group (P < 0.0001, adjusted for hormone receptor status). Single-cell ERBB2 FISH analysis of cellular heterogeneity identified the fraction of ERBB2 nonamplified cells as a driver of therapeutic resistance. These data suggest HER2 heterogeneity is associated with resistance to HER2-targeted therapy and should be considered in efforts to optimize treatment strategies. SIGNIFICANCE: HER2-targeted therapies improve cure rates in HER2-positive breast cancer, suggesting chemotherapy can be avoided in a subset of patients. We show that HER2 heterogeneity, particularly the fraction of ERBB2 nonamplified cancer cells, is a strong predictor of resistance to HER2 therapies and could potentially be used to optimize treatment selection.See related commentary by Okines and Turner, p. 2369.This article is highlighted in the In This Issue feature, p. 2355.

Impact of molecular subtype and race on HR+, HER2- breast cancer survival

PURPOSE

There is an urgent need to understand the biological factors contributing to the racial survival disparity among women with hormone receptor-positive (HR+), HER2- breast cancer. In this study, we examined the impact of PAM50 subtype on 10-year mortality rate in women with HR+, HER2- breast cancer by race.

METHODS

Women with localized, HR+, HER2- breast cancer diagnosed between 2002 and 2012 from two population-based cohorts were evaluated. Archival tumors were obtained and classified by PAM50 into four molecular subtypes (i.e., luminal A, luminal B, HER2-enriched, and basal-like). The molecular subtypes within HR+, HER2- breast cancers and corresponding 10-year mortality rate were compared between Black and Non-Hispanic White (NHW) women using Cox proportional hazard ratios and survival analysis, adjusting for covariates.

RESULTS

In this study, 318 women with localized, HR+, HER2- breast cancer were included-227 Black (71%) and 91 NHW (29%). Young Black women (age ≤ 50) had the highest proportion of HR+, non-luminal A tumors (47%), compared to young NHW (10%), older Black women (31%), and older NHW (30%). Overall, women with HR+, non-luminal A subtypes had a higher 10-year mortality rate compared to HR+, luminal A subtypes after adjustment for age, stage, and income (HR 4.21 for Blacks, 95% CI 1.74-10.18 and HR 3.44 for NHW, 95% CI 1.31-9.03). Among HR+, non-luminal A subtypes there was, however, no significant racial difference in 10-yr mortality observed (Black vs. NHW: HR 1.23, 95% CI 0.58-2.58).

CONCLUSION

Molecular subtype classification highlights racial disparities in PAM50 subtype distribution among women with HR+, HER2- breast cancer. Among women with HR+, HER2- breast cancer, racial survival disparities are ameliorated after adjusting for molecular subtype.

Cancer Antigen 15-3/Mucin 1 Levels in CCTG MA.32: A Breast Cancer Randomized Trial of Metformin vs Placebo

Background

Circulating levels of cancer antigen (CA) 15-3, a tumor marker and regulator of cellular metabolism, were reduced by metformin in a nonrandomized neoadjuvant study. We examined the effects of metformin (vs placebo) on CA 15-3 in participants of MA.32, a phase III randomized trial in early-stage breast cancer.

Methods

A total of 3649 patients with T1-3, N0-3, M0 breast cancer were randomly assigned; pretreatment and 6-month on-treatment fasting plasma were centrally assayed for CA 15-3. Genomic DNA was analyzed for the rs11212617 single nucleotide polymorphism. Absolute and relative change of CA 15-3 (metformin vs placebo) were compared using Wilcoxon rank and t tests. Regression models adjusted for baseline differences and assessed key interactions. All statistical tests were 2-sided.

Results

Mean (SD) age was 52.4 (10.0) years. The majority of patients had T2/3, node-positive, hormone receptor-positive, HER2-negative breast cancer treated with (neo)adjuvant chemotherapy and hormone therapy. Mean (SD) baseline CA 15-3 was 17.7 (7.6) and 18.0 (8.1 U/mL). At 6 months, CA 15-3 was statistically significantly reduced in metformin vs placebo arms (absolute geometric mean reduction in CA 15-3 = 7.7% vs 2.0%, P < .001; relative metformin: placebo level of CA 15-3 [adjusted for age, baseline body mass index, and baseline CA 15-3] = 0.94, 95% confidence interval = 0.92 to 0.96). This reduction was independent of tumor characteristics, perioperative systemic therapy, baseline body mass index, insulin, and the single nucleotide polymorphism status (all Ps > .11).

Conclusions

Our observation that metformin reduces CA 15-3 by approximately 6% was corroborated in a large placebo-controlled randomized trial. The clinical implications of this reduction in CA 15-3 will be explored in upcoming efficacy analyses of breast cancer outcomes in MA.32.

New targets in endocrine-resistant hormone receptor-positive breast cancer

Endocrine-based treatments are the backbone of initial therapy for advanced hormone receptor-positive breast cancers. Developing new therapeutic strategies to address resistance to endocrine therapy is an area of active research. In this review, we discuss targeted therapies that are currently the standard of care, as well as agents that are at present under investigation as potential treatments for advanced hormone receptor-positive breast cancer.

Human and Machine Intelligence Together Drive Drug Repurposing in Rare Diseases

Repurposing is an increasingly attractive method within the field of drug development for its efficiency at identifying new therapeutic opportunities among approved drugs at greatly reduced cost and time of more traditional methods. Repurposing has generated significant interest in the realm of rare disease treatment as an innovative strategy for finding ways to manage these complex conditions. The selection of which agents should be tested in which conditions is currently informed by both human and machine discovery, yet the appropriate balance between these approaches, including the role of artificial intelligence (AI), remains a significant topic of discussion in drug discovery for rare diseases and other conditions. Our drug repurposing team at Vanderbilt University Medical Center synergizes machine learning techniques like phenome-wide association study-a powerful regression method for generating hypotheses about new indications for an approved drug-with the knowledge and creativity of scientific, legal, and clinical domain experts. While our computational approaches generate drug repurposing hits with a high probability of success in a clinical trial, human knowledge remains essential for the hypothesis creation, interpretation, "go-no go" decisions with which machines continue to struggle. Here, we reflect on our experience synergizing AI and human knowledge toward realizable patient outcomes, providing case studies from our portfolio that inform how we balance human knowledge and machine intelligence for drug repurposing in rare disease.

Targeting the PI3K/AKT/mTOR Pathway in Hormone-Positive Breast Cancer

Approximately 70% of invasive breast cancers have some degree of dependence on the estrogen hormone for cell proliferation and growth. These tumors have estrogen and/or progesterone receptors (ER/PR+), generally referred to as hormone receptor positive (HR+) tumors, as indicated by the presence of positive staining and varying intensity levels of estrogen and/or progesterone receptors on immunohistochemistry. Therapies that inhibit ER signaling pathways, such as aromatase inhibitors (letrozole, anastrozole, exemestane), selective ER modulators (tamoxifen), and ER down-regulators (fulvestrant), are the mainstays of treatment for hormone-receptor-positive breast cancers. However, de novo or acquired resistance to ER targeted therapies is present in many tumors, leading to disease progression. The PI3K/AKT/mTOR pathway is implicated in sustaining endocrine resistance and has become the target of many new drugs for ER+ breast cancer. This article reviews the function of the phosphoinositide 3-kinase (PI3K)/AKT/mTOR pathway and the various classes of PI3K pathway inhibitors that have been developed to disrupt this pathway signaling for the treatment of hormone-receptor-positive breast cancer.

Patient-Reported Outcomes in Patients With PIK3CA-Mutated Hormone Receptor-Positive, Human Epidermal Growth Factor Receptor 2-Negative Advanced Breast Cancer From SOLAR-1

PURPOSE

In the phase III SOLAR-1 trial (NCT02437318), the PI3Kα-selective inhibitor and degrader alpelisib significantly improved median progression-free survival when added to fulvestrant in patients with phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA)-mutated, hormone receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer. We assessed health-related quality of life using patient-reported outcome measures in these patients.

MATERIALS AND METHODS

In the PIK3CA-mutant cohort, 341 patients were randomly assigned 1:1 to receive alpelisib 300 mg daily or placebo plus fulvestrant 500 mg on days 1 and 15 of cycle 1 and on day 1 of subsequent 28-day cycles. Patient-reported outcomes were evaluated with the European Organisation for Research and Treatment of Cancer QoL of Cancer Patients and Brief Pain Inventory-Short Form questionnaires. Changes from baseline and time to 10% deterioration were analyzed using repeated measurement models and Cox models, respectively.

RESULTS

Global Health Status/QoL and functional status were maintained from baseline (mean changes < 10 points) in the alpelisib (overall change from baseline [95% CI], -3.50 [-8.02 to 1.02]) and placebo arms (overall change from baseline [95% CI], 0.27 [-4.48 to 5.02]). Overall treatment effect in Global Health Status/QoL was not significantly different between arms (-3.77; 95% CI, -8.35 to 0.80; P = .101). Time to 10% deterioration for Global Health Status/QoL was similar between arms (hazard ratio, 1.03; 95% CI, 0.72 to 1.48). Compared with placebo, deterioration in social functioning and in diarrhea, appetite loss, nausea or vomiting, and fatigue symptom subscales occurred with alpelisib. Numerical improvement in Worst Pain was observed with alpelisib versus placebo (42% v 32%, week 24; P = .090).

CONCLUSION

In SOLAR-1, there was no statistical difference in deterioration of Global Health Status/QoL between arms, whereas symptom subscales favored placebo for diarrhea, appetite loss, nausea or vomiting, and fatigue, known side effects of alpelisib. Treatment decisions must consider efficacy and tolerability; taken with clinical efficacy, these results support the benefit-risk profile of alpelisib in patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative PIK3CA-mutated advanced breast cancer.

Effect of metformin versus placebo on metabolic factors in the MA.32 randomized breast cancer trial

Metformin may exert anticancer effects through indirect (mediated by metabolic changes) or direct mechanisms. The goal was to examine metformin impact on metabolic factors in non-diabetic subjects and determine whether this impact varies by baseline BMI, insulin, and rs11212617 SNP in CCTG MA.32, a double-blind placebo-controlled randomized adjuvant breast cancer (BC) trial. 3649 subjects with T1-3, N0-3, M0 BC were randomized; pretreatment and 6-month on-treatment fasting plasma was centrally assayed for insulin, leptin, highly sensitive C-reactive protein (hsCRP). Glucose was measured locally and homeostasis model assessment (HOMA) calculated. Genomic DNA was analyzed for the rs11212617 SNP. Absolute and relative change of metabolic factors (metformin versus placebo) were compared using Wilcoxon rank and t-tests. Regression models were adjusted for baseline differences and assessed interactions with baseline BMI, insulin, and the SNP. Mean age was 52 years. The majority had T2/3, node positive, hormone receptor positive, HER2 negative BC treated with (neo)adjuvant chemotherapy and hormone therapy. Median baseline body mass index (BMI) was 27.4 kg/m2 (metformin) and 27.3 kg/m2 (placebo). Median weight change was -1.4 kg (metformin) vs +0.5 kg (placebo). Significant improvements were seen in all metabolic factors, with 6 month standardized ratios (metformin/placebo) of 0.85 (insulin), 0.83 (HOMA), 0.80 (leptin), and 0.84 (hsCRP), with no qualitative interactions with baseline BMI or insulin. Changes did not differ by rs11212617 allele. Metformin (vs placebo) led to significant improvements in weight and metabolic factors; these changes did not differ by rs11212617 allele status.

Randomized Phase III Postoperative Trial of Platinum-Based Chemotherapy Versus Capecitabine in Patients With Residual Triple-Negative Breast Cancer Following Neoadjuvant Chemotherapy: ECOG-ACRIN EA1131

PURPOSE

Patients with triple-negative breast cancer (TNBC) and residual invasive disease (RD) after completion of neoadjuvant chemotherapy (NAC) have a high-risk for recurrence, which is reduced by adjuvant capecitabine. Preclinical models support the use of platinum agents in the TNBC basal subtype. The EA1131 trial hypothesized that invasive disease-free survival (iDFS) would not be inferior but improved in patients with basal subtype TNBC treated with adjuvant platinum compared with capecitabine.

PATIENTS AND METHODS

Patients with clinical stage II or III TNBC with ≥ 1 cm RD in the breast post-NAC were randomly assigned to receive platinum (carboplatin or cisplatin) once every 3 weeks for four cycles or capecitabine 14 out of 21 days every 3 weeks for six cycles. TNBC subtype (basal v nonbasal) was determined by PAM50 in the residual disease. A noninferiority design with superiority alternative was chosen, assuming a 4-year iDFS of 67% with capecitabine.

RESULTS

Four hundred ten of planned 775 participants were randomly assigned to platinum or capecitabine between 2015 and 2021. After median follow-up of 20 months and 120 iDFS events (61% of full information) in the 308 (78%) patients with basal subtype TNBC, the 3-year iDFS for platinum was 42% (95% CI, 30 to 53) versus 49% (95% CI, 39 to 59) for capecitabine. Grade 3 and 4 toxicities were more common with platinum agents. The Data and Safety Monitoring Committee recommended stopping the trial as it was unlikely that further follow-up would show noninferiority or superiority of platinum.

CONCLUSION

Platinum agents do not improve outcomes in patients with basal subtype TNBC RD post-NAC and are associated with more severe toxicity when compared with capecitabine. Participants had a lower than expected 3-year iDFS regardless of study treatment, highlighting the need for better therapies in this high-risk population.

Hydroxychloroquine as Pre-exposure Prophylaxis for Coronavirus Disease 2019 (COVID-19) in Healthcare Workers: A Randomized Trial

Background

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a rapidly emerging virus causing the ongoing coronavirus disease 2019 (COVID-19) pandemic with no known effective prophylaxis. We investigated whether hydroxychloroquine could prevent SARS-CoV-2 in healthcare workers at high risk of exposure.

Methods

We conducted a randomized, double-blind, placebo-controlled clinical trial of healthcare workers with ongoing exposure to persons with SARS-CoV-2, including those working in emergency departments, intensive care units, COVID-19 hospital wards, and first responders. Participants across the United States and in the Canadian province of Manitoba were randomized to hydroxychloroquine loading dose then 400 mg once or twice weekly for 12 weeks. The primary endpoint was confirmed or probable COVID-19–compatible illness. We measured hydroxychloroquine whole-blood concentrations.

Results

We enrolled 1483 healthcare workers, of whom 79% reported performing aerosol-generating procedures. The incidence of COVID-19 (laboratory-confirmed or symptomatic compatible illness) was 0.27 events/person-year with once-weekly and 0.28 events/person-year with twice-weekly hydroxychloroquine compared with 0.38 events/person-year with placebo. For once-weekly hydroxychloroquine prophylaxis, the hazard ratio was .72 (95% CI, .44–1.16; P = .18) and for twice-weekly was .74 (95% CI, .46–1.19; P = .22) compared with placebo. Median hydroxychloroquine concentrations in whole blood were 98 ng/mL (IQR, 82–120) with once-weekly and 200 ng/mL (IQR, 159–258) with twice-weekly dosing. Hydroxychloroquine concentrations did not differ between participants who developed COVID-19–compatible illness (154 ng/mL) versus participants without COVID-19 (133 ng/mL; P = .08).

Conclusions

Pre-exposure prophylaxis with hydroxychloroquine once or twice weekly did not significantly reduce laboratory-confirmed COVID-19 or COVID-19–compatible illness among healthcare workers.

Clinical Trials Registration

Clinicaltrials.gov NCT04328467.

Romidepsin (HDACi) plus cisplatin and nivolumab triplet combination in patients with metastatic triple negative breast cancer (mTNBC)

1076

Background: Histone deacetylase inhibitors (HDACi) upregulate genes involved in antigen presentation machinery and increase expression of natural killer group 2, member D ligands (NKG2DL), thus resulting in enhanced tumor cell recognition and response to PD-1/CTLA-4 blockade. Cisplatin and HDACi combination synergistically induces cytotoxicity, apoptosis, and DNA damage. This phase I-II trial investigated combination of romidepsin (HDACi) plus cisplatin and nivolumab (PD-1 inhibitor) in mTNBC. Patients and Methods: Eligible patients had mTNBC with any number of prior chemotherapies. Phase I was 3+3 dose-escalation design with three dose levels of romidepsin (8, 10, 12mg/m2, D2, 9) plus cisplatin 75mg/m2 D 1 every 21 days. Phase II treatment included romidepsin plus cisplatin plus nivolumab 360mg every 21 days and was designed according to Simon’s two stage minimax design. Primary endpoints were recommended phase 2 dose (RP2D) and objective response rate (ORR). Additional endpoints included safety, PFS, and pharmacokinetics. Results: 51 patients were enrolled (N=13 phase I, N=38 phase II) between 2015-2020. 69% had received ≥1 prior metastatic chemotherapy, 47% had prior platinum, 53% had liver metastasis, 12% had BRCA1/2 mutation, and 11% had PD-L1 positive disease. There were no dose limiting toxicities in phase I. The RP2D was romidepsin 12mg/m2 D2,9 + cisplatin 75mg/m2 D1 + nivolumab 360mg D1 every 21 days. Thrombocytopenia (G3:27%, G4:0%), neutropenia (G3:25%, G4:0%), anemia (G3:22%, G4:0%), nausea (G3:22%, G4:0%), and vomiting (G3:20%, G4:0%) were the most common grade 3/4 adverse events. 21% of patients had immune AEs (G3-4:8%). Among 34 evaluable phase II patients, ORR was 44% (Table), median PFS was 4.4 months, and 1-year PFS was 23%. Median OS was 10.3 months and 1-year OS was 43%. No pharmacokinetic interactions were detected with co-administration of romidepsin-cisplatin-nivolumab. Conclusions: The triplet combination of romidepsin plus cisplatin and nivolumab was well tolerated and shows encouraging efficacy in pretreated mTNBC, including in patients with PD-L1 negative disease and in those with liver metastasis. Correlative biomarker work is ongoing. This combination warrants further evaluation in larger studies. Clinical trial information: NCT02393794 .[Table: see text]

A randomized phase III post-operative trial of platinum-based chemotherapy (P) versus capecitabine (C) in patients (pts) with residual triple-negative breast cancer (TNBC) following neoadjuvant chemotherapy (NAC): ECOG-ACRIN EA1131

605

Background: Pts with TNBC who have residual invasive disease (RD) after completion of NAC have a very high risk for recurrence, which is reduced by adjuvant capecitabine (C). Pre-clinical models support the use of platinum agents (P) in the TNBC basal subtype. EA1131 tested the hypothesis that invasive disease-free survival (iDFS) would not be inferior but improved in pts with basal subtype TNBC after NAC with the adjuvant use of a P instead of C (primary objective). Methods: Pts with clinical stage II/III TNBC post neoadjuvant taxane +/- anthracycline-based chemotherapy with at least 1 cm RD in the surgical specimen were randomized (1:1) to receive P (carboplatin or cisplatin once every 3 weeks for 4 cycles) or C (14/7d every 3 weeks for 6 cycles). TNBC subtype (basal vs. non-basal) was analyzed in the surgical specimen by PAM50. A non-inferiority design (non-inferiority margin of hazard ratio [HR] of 1.154) with superiority alternative (alternative HR of 0.754) was chosen, assuming a 4-year iDFS of 67% for the C arm. Non-inferiority was tested first. If non-inferiority was shown, a formal test for superiority of P compared to C would be conducted. Results: 401 participants were randomized to P or C between 2015 and 2020 (recruitment goal, 775), 310 (77%) had TNBC basal subtype disease (primary analysis population). Pts’ median age was 52 years, 71% were White and 19% Black. At diagnosis, most tumors were high grade (78%), T2 (59%), 47% N0, and 40% N1. Residual tumors were 37% ypT1, 44% ypT2, and 47% ypN0. Overall incidence of any toxicity was similar (83% with P, 80% with C), but grade 3 and 4 toxicities (no grade 5) were more common with P (25% vs 15%). After median follow-up of 18 months, 113 iDFS events (58% of full information) had occurred. 3-year iDFS for P arm was 40% (95%CI, 29%-51%) and 44% (95%CI, 32%-55%) for C arm. The HR for arms P/C was 1.09 (95% Repeated Confidence Interval, 0.62-1.90) and the probability of eventually rejecting the null of inferiority (i.e., conditional power) was 6%. The Data Safety and Monitoring Committee recommended stopping the trial at the 5th interim analysis in March 2021 since it was unlikely that the trial would be able to show non-inferiority or superiority of the P arm. Conclusions: Participants with TNBC with RD after NAC had a lower than expected 3-year iDFS regardless of study treatment. Available data show that it is very unlikely that the study would be able to establish non-inferiority of P to C. In addition, severe toxicities were more common with P. In pts with TNBC, particularly basal subtype, with at least 1 cm RD after NAC and high-risk of recurrence, adjuvant P use does not improve outcomes. Correlative analyses of RD tissue (NGS), circulating markers (ctDNA and CTC pre/post treatment), and patient-reported outcomes (PRO) questionnaires will now occur. Clinical trial information: NCT02445391.

Inhibition of the PI3K/mTOR Pathway in Breast Cancer to Enhance Response to Immune Checkpoint Inhibitors in Breast Cancer

OBJECTIVES

Inhibition of the PI3K/mTOR pathway suppresses breast cancer (BC) growth, enhances anti-tumor immune responses, and works synergistically with immune checkpoint inhibitors (ICI). The objective here was to identify a subclass of PI3K inhibitors that, when combined with paclitaxel, is effective in enhancing response to ICI.

METHODS

C57BL/6 mice were orthotopically implanted with syngeneic luminal/triple-negative-like PyMT cells exhibiting high endogenous PI3K activity. Tumor growth in response to treatment with anti-PD-1 + anti-CTLA-4 (ICI), paclitaxel (PTX), and either the PI3Kα-specific inhibitor alpelisib, the pan-PI3K inhibitor copanlisib, or the broad spectrum PI3K/mTOR inhibitor gedatolisib was evaluated in reference to monotherapy or combinations of these therapies. Effects of these therapeutics on intratumoral immune populations were determined by multicolor FACS.

RESULTS

Treatment with alpelisib + PTX inhibited PyMT tumor growth and increased tumor-infiltrating granulocytes but did not significantly affect the number of tumor-infiltrating CD8+ T cells and did not synergize with ICI. Copanlisib + PTX + ICI significantly inhibited PyMT growth and increased activation of intratumoral CD8+ T cells as compared to ICI alone, yet did not inhibit tumor growth more than ICI alone. In contrast, gedatolisib + ICI resulted in significantly greater inhibition of tumor growth compared to ICI alone and induced durable dendritic-cell, CD8+ T-cell, and NK-cell responses. Adding PTX to this regimen yielded complete regression in 60% of tumors.

CONCLUSION

PI3K/mTOR inhibition plus PTX heightens response to ICI and may provide a viable therapeutic approach for treatment of metastatic BC.

NCCN Guidelines® Insights: Breast Cancer, Version 4.2021

The NCCN Guidelines for Breast Cancer include up-to-date guidelines for clinical management of patients with carcinoma in situ, invasive breast cancer, Paget disease, phyllodes tumor, inflammatory breast cancer, male breast cancer, and breast cancer during pregnancy. These guidelines are developed by a multidisciplinary panel of representatives from NCCN Member Institutions with breast cancer-focused expertise in the fields of medical oncology, surgical oncology, radiation oncology, pathology, reconstructive surgery, and patient advocacy. These NCCN Guidelines Insights focus on the most recent updates to recommendations for adjuvant systemic therapy in patients with nonmetastatic, early-stage, hormone receptor-positive, HER2-negative breast cancer.

Race, Ethnicity, and Clinical Outcomes in Hormone Receptor-Positive, HER2-Negative, Node-Negative Breast Cancer in the Randomized TAILORx Trial

BACKGROUND

Black race is associated with worse outcomes in early breast cancer. We evaluated clinicopathologic characteristics, the 21-gene recurrence score (RS), treatment delivered, and clinical outcomes by race and ethnicity among women who participated in the Trial Assigning Individualized Options for Treatment.

METHODS

The association between clinical outcomes and race (White, Black, Asian, other or unknown) and ethnicity (Hispanic vs non-Hispanic) was examined using proportional hazards models. All P values are 2-sided.

RESULTS

Of 9719 eligible women with hormone receptor-positive, HER2-negative, node-negative breast cancer, there were 8189 (84.3%) Whites, 693 (7.1%) Blacks, 405 (4.2%) Asians, and 432 (4.4%) with other or unknown race. Regarding ethnicity, 889 (9.1%) were Hispanic. There were no substantial differences in RS or ESR1, PGR, or HER2 RNA expression by race or ethnicity. After adjustment for other covariates, compared with White race, Black race was associated with higher distant recurrence rates (hazard ratio [HR] = 1.60, 95% confidence intervals [CI] = 1.07 to 2.41) and worse overall survival in the RS 11-25 cohort (HR = 1.51, 95% CI = 1.06 to 2.15) and entire population (HR = 1.41, 95% CI = 1.05 to 1.90). Hispanic ethnicity and Asian race were associated with better outcomes. There was no evidence of chemotherapy benefit for any racial or ethnic group in those with a RS of 11-25.

CONCLUSIONS

Black women had worse clinical outcomes despite similar 21-gene assay RS results and comparable systemic therapy in the Trial Assigning Individualized Options for Treatment. Similar to Whites, Black women did not benefit from adjuvant chemotherapy if the 21-gene RS was 11-25. Further research is required to elucidate the basis for this racial disparity in prognosis.

Abstract PD1-05: Latest findings from the breast cancer cohort in SUMMIT - a phase 2 ‘basket’ trial of neratinib + trastuzumab + fulvestrant for HER2-mutant, hormone receptor-positive, metastatic breast cancer

Background: HER2 mutations are oncogenic in hormone receptor positive (HR+) metastatic breast cancer (MBC), and may confer resistance to prior endocrine therapy but retain sensitivity to neratinib. Neratinib is an oral, irreversible, pan-HER tyrosine kinase inhibitor with clinical activity either as a single agent or in combination with fulvestrant in HER2-mutated, HER2-non-amplified MBC. Genomic analyses suggest that acquired resistance to neratinib can occur via additional HER2 alterations, which may alter HER2-pathway signaling. We investigated whether dual HER2-targeted therapy could improve clinical benefit in a cohort of patients with HER2-mutant, HR+ MBC treated with neratinib + trastuzumab + fulvestrant (N+T+F) from SUMMIT - a phase 2 basket trial (NCT01953926).

Methods: Patients with HR+ MBC with known or suspected pathogenic HER2 mutation(s) identified by genomic sequencing were eligible to receive N+T+F (oral neratinib 240 mg/day, i.v. trastuzumab 8 mg/kg initially followed by 6 mg/kg every 3 weeks, and i.m. fulvestrant 500 mg on days 1&15 of month 1, then on day 1 every 4 weeks). Loperamide prophylaxis was mandatory during the first 2 treatment cycles. There was no restriction on the number of prior lines of systemic treatment for MBC. Efficacy endpoints: confirmed objective response rate and clinical benefit rate (RECIST v1.1); duration of response; progression-free survival.

Results: As of 22-May-2020, 46 patients were enrolled in the N+T+F cohort and received at least 1 dose of study medication (safety population). 14 unique HER2 allelic variants were identified: 8 kinase domain missense; 1 extracellular domain missense; 2 transmembrane domain missense; 2 exon-20 insertion; 1 exon-19 deletion. The most common HER2 mutant variant was L755S (n=15, 33%) Median number of prior systemic regimens for metastatic disease was 4 (range 0-10); 34 (74%) patients had received prior fulvestrant, and 31 (67%) patients had received prior cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor therapy. 16 (35%) patients had ductal histology, 29 (63%) had lobular carcinoma, and 1 (2%) had mixed ductal and lobular carcinoma. At this time, 30/46 patients had RECIST measurable disease and are efficacy evaluable (ongoing patients who did not have the opportunity for their first post-baseline tumor assessment were excluded); clinical activity - see Table. Diarrhea was the most commonly reported adverse event (80% any grade) with 15 (33%) patients reporting grade 3 diarrhea (no grade 4 diarrhea). 10 patients (22%) had a neratinib dose reduction due to diarrhea but no patients discontinued treatment due to diarrhea.

Conclusions: The combination of N+T+F demonstrated encouraging clinical activity in heavily pre-treated HER2-mutant, HR+, HER2-non-amplified MBC, including patients who had previously received either fulvestrant and/or CDK4/6 inhibitor-based therapies. While the rate of grade 3 diarrhea was higher than that observed with single-agent neratinib in SUMMIT, this was manageable through loperamide prophylaxis, and no patients discontinued study treatment due to diarrhea. SUMMIT has recently been amended to evaluate N+T+F, T+F and F (1:1:1 randomization) and continues to enroll patients.

RECIST measurable and efficacy evaluable patients (n=30)Confirmed objective response,a n (%)12 (40)CR0PR12ORR, % (95% CI)40 (23-59)Best overall response, n (%)18 (60)CR0PR18Best overall response rate, % (95% CI)60 (41-77)Medianb DOR, months (95% CI)8.4 (4.1-NE)Clinical benefit,c n (%)14 (47)CR or PR12SD ≥24 weeks2CBR, % (95% CI)47 (28-66)Medianb PFS, months (95% CI)8.3 (4.2-12.5)aORR is defined as either a CR or a PR that is confirmed no less than 4 weeks after the criteria for response are initially met; bKaplan-Meier analysis; cCBR is defined as confirmed CR or PR or SD for ≥24 weeks; CR, complete response; CBR, clinical benefit rate; DOR, duration of response; NE, not estimable; ORR, objective response rate; PFS, progression-free survival; PR, partial response; SD, stable disease.

Citation Format: Komal Jhaveri, Cristina Saura, Angel Guerrero-Zotano, Iben Spanggaard, François-Clement Bidard, Jonathan W Goldman, José A García-Sáenz, Andrés Cervantes, Valentina Boni, John Crown, Adam Brufsky, Sherene Loi, Barbara Haley, Ingrid A Mayer, Stephen Chia, Janice Lu, James Waisman, Noa Efrat Ben-Baruch, Mark E Burkard, Jennifer M Suga, Lucía González-Cortijo, Bruno Perrucci, Feng Xu, Sofia Wong, Jie Zhang, Lisa D Eli, Alshad S Lalani, Hans Wildiers. Latest findings from the breast cancer cohort in SUMMIT - a phase 2 ‘basket’ trial of neratinib + trastuzumab + fulvestrant for HER2-mutant, hormone receptor-positive, metastatic breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PD1-05.

Abstract PD2-06: Clinical outcomes of alpelisib plus fulvestrant in hormone receptor-positive, human epidermal growth factor receptor-2-negative advanced breast cancer with PIK3CA alterations detected in plasma ctDNA by next-generation sequencing: Biomarker analysis from the SOLAR-1 study

Introduction: The PI3K pathway is often hyperactivated in cancer as a result of an altered PI3K isoform and/or loss of phosphatase and tensin homolog function. Approximately 40% of patients (pts) with hormone receptor-positive (HR+), human epidermal growth factor receptor-2-negative (HER2−) advanced breast cancer (ABC) have tumors with mutations in PIK3CA, which encodes the α-isoform of PI3K, p110α. These mutations are known to cause hyperactivation of the PI3K pathway, which contributes to cell proliferation, drug resistance, and poor prognoses. Alpelisib (ALP) is an α-selective PI3K inhibitor that, in combination with fulvestrant (FUL), prolonged median progression-free survival (mPFS) in pts with HR+, HER2−, PIK3CA-mutant ABC following progression on/after prior aromatase inhibitor in the phase 3 SOLAR-1 trial. In SOLAR-1, prospective PIK3CA mutation testing was performed on tumor tissue using PCR-based assays. Through retrospective analysis, efficacy of ALP was demonstrated in subgroups of pts with PIK3CA alteration(s) in tumor tissue and mutation(s) in ctDNA, detected by next-generation sequencing (NGS) and PCR, respectively. In this exploratory biomarker analysis, we assessed clinical outcomes of pts with PIK3CA alteration(s), detected in ctDNA by NGS.Methods: SOLAR-1 is a phase 3, randomized, double-blind, placebo-controlled study of ALP 300 mg vs placebo taken daily with FUL 500 mg every 28 days + Cycle 1 Day 15 in men and postmenopausal women with HR+, HER2- ABC. Retrospectively, the full exonic region of the PIK3CA gene was sequenced using the Foundation Medicine 324-gene ctDNA panel in plasma ctDNA collected at baseline. mPFS was assessed using Kaplan-Meier methodology per investigator assessment.Results: Of 572 pts in SOLAR-1, 381 pts (66.6%) across both PIK3CA-mutant and nonmutant cohorts had valid plasma ctDNA data. Of these pts, 193 (50.7%) had a PIK3CA alteration; 168 (87%) had PCR-detectable mutations and 147 (76%) had a single alteration. A total of 70 (36%) and 102 (53%) pts had alterations in exons 9 and 20, respectively. ALP plus FUL prolonged mPFS in pts with PIK3CA alterations detected in plasma ctDNA by NGS (n=101; Table). Clinical benefit was also observed in pts with PCR-detectable mutations (n=88), single mutations (n=83), and pts with mutations in exon 9 (n=34) and exon 20 (n=54). Pt numbers were low, and wide 95% CIs were observed in groups with alterations not detectable by PCR (n=13) and in pts with multiple alterations. Some limitations of this retrospective plasma analysis include that this is a subgroup (66.6%) of the SOLAR-1 pt population and that the subgroup of pts with non-altered PIK3CA included pts with a PIK3CA mutation in their tumor tissue. Conclusions: ALP plus FUL demonstrated clinical benefit in pts with PIK3CA mutations detected in plasma ctDNA by NGS, in pts with single alterations, and in pts with alterations in exons 9 and 20. Results were consistent across pt groups, except in those with alterations not detectable by PCR. In conclusion, these data demonstrate a consistent clinical benefit of ALP plus FUL in various groups of pts with PIK3CA alterations detected in ctDNA by NGS.

Clinical Outcomes of Patients With PIK3CA Alterations Detected in Plasma ctDNA by NGS in SOLAR-1Alpelisib + fulvestrantPlacebo + fulvestrantHR (95% CI)Events/N (%)mPFS, mo (95% CI)Events/N(%)mPFS, mo (95% CI)PIK3CA altered vs non-alteredAltered58/101(57.4)11.04(7.72-16.16)73/92(79.3)3.65(2.86-6.80)0.47(0.33-0.67)Non-altered40/87(46.0)10.87(5.59-16.76)60/101(59.4)5.45(3.75-9.00)0.60(0.40-0.91)PIK3CA: alteration detectable by PCR vs alteration not detectable by PCRDetectable52/88(59.1)12.48(7.36-18.37)66/80(82.5)3.58(2.37-5.65)0.44(0.30-0.64)Not detectable6/13(46.2)8.48(2.69-NA)7/12(58.3)7.39(1.87-12.98)1.12(0.35-3.56)PIK3CA: number of alterationsSingle45/83(54.2)12.88(7.36-18.50)50/64(78.1)3.58(1.87-6.11)0.43(0.28-0.65)Multiple13/18(72.2)9.00(3.68-18.37)23/28(82.1)4.63(3.48-9.63)0.55(0.25-1.20)PIK3CA alterations in exon 9 or exon 20Exon 918/34(52.9)15.21(7.03-NA)29/36(80.6)3.66(2.86-7.36)0.31(0.16-0.61)Exon 2034/54(63.0)10.91(5.72-18.37)40/48(83.3)3.52(1.87-6.11)0.51(0.31-0.82)CI, confidence interval; ctDNA, circulating tumor DNA; HR, hazard ratio; mPFS, median progression-free survival; mo, months; NA, not available; NGS, next-generation sequencing.

Citation Format: Eva M. Ciruelos, Sibylle Loibl, Ingrid A. Mayer, Mario Campone, Hope S. Rugo, Monica Arnedos, Hiroji Iwata, Pier Franco Conte, Fabrice André, Albert Reising, Chong Ma, Michelle Miller, Naveen Babbar, Dejan Juric. Clinical outcomes of alpelisib plus fulvestrant in hormone receptor-positive, human epidermal growth factor receptor-2-negative advanced breast cancer with PIK3CA alterations detected in plasma ctDNA by next-generation sequencing: Biomarker analysis from the SOLAR-1 study [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PD2-06.

Abstract PS12-13: Balixafortide (a CXCR4 antagonist) plus eribulin in HER2 negative metastatic breast cancer: Final analysis from the Phase 1 single arm trial

Background: Balixafortide (B) is a potent, selective antagonist of the chemokine receptor CXCR4. High CXCR4 levels correlate with aggressive metastatic phenotypes and poor prognosis in metastatic breast cancer (MBC). Efficacy and safety data were published recently from the Phase 1 trial investigating B + eribulin (E) in patients with HER2 negative MBC1. We report the final safety and efficacy analyses from this trial, including an assessment of dose-response and adverse events of particular interest (AEPIs) (e.g. neutropenia, peripheral neuropathy).

Methods: In this single-arm, dose escalation trial, patients (pts) received E + increasing doses of B using a 3+3 design in 3 parts: Part I cohorts received low B doses (0.5−1mg/kg) + increasing E doses (1.1−1.4mg/m2); Part II dose-escalation cohort for B (1−5.5mg/kg) + 1.4mg/m2 E; Expanded Cohort (EC) to confirm safety and efficacy of B 5.5mg/kg + 1.4mg/m2 E. Most cohorts received E on days 2 and 9, and B on days 1−3 and 8−10 of 21-day cycles.

Results: At entry, all 56 women (age range 33−82 years) were HER2 negative, CXCR4 positive. Most pts were Caucasian and heavily pretreated in the metastatic setting (line of chemotherapy on study: 29% 2nd line, 50% 3rd line, 21% 4th line). 75% were hormone receptor positive and 23% had triple negative breast cancer.

A linear dose-exposure was observed over the entire dose range tested for B. Cmax and AUC for E were within published ranges.

Safety findings (including AEPIs) remained similar to those reported previously1.

No dose-limiting toxicities were confirmed; therefore, the maximum tolerated dose of B was not reached. The highest B dose evaluated was 5.5mg/kg; pharmacokinetic evaluation showed that further protocolled dose increments of B would not have provided a sufficient increase in plasma levels. In addition, the objective response rate in Part II was 3-fold greater than published for eribulin alone which suggested that the anti-tumor activity of B was worthy of further exploration at 5.5mg/kg in the EC.

Efficacy data for the trial are shown in the table.

These data suggest a potential dose-response relationship for B across all efficacy endpoints, with efficacy being numerically greatest in the EC. While PFS and OS should be interpreted with caution in single arm trials, these data suggest potential benefit for this combination. Further analyses will be presented.

Responses were observed regardless of line of chemotherapy on study or extent of CXCR4 expression and were numerically higher in hormone receptor positive patients.

Conclusions: A consistent dose response effect for B + E was suggested across all efficacy endpoints for heavily pretreated pts with HER2 negative MBC. When these results are compared with published data for E monotherapy in similar populations, the EC consistently shows numerically greater benefit for all efficacy endpoints2, 3.

The safety and tolerability of B + E appear comparable to published data on E or B alone, particularly for neutropenia and peripheral neuropathy1.

These results suggest that B + E could potentially provide a new treatment option in heavily pretreated patients with HER2 negative MBC. A Phase 3 trial exploring efficacy and safety of B 5.5mg/kg + E is ongoing.

1. Pernas S et al. Lancet Oncol. 2018; 19: 812−242. Cortes J et al. Lancet. 2011; 377: 914−9233. Kaufman PA et al. J Clin Oncol. 2015; 33: 594−601

Part II(N=21)Expanded Cohort(N=24)Overall Efficacy Population(N=54)Objective Response Rate (95% CI)33% (15−57)38% (19−59)30% (18−44)median duration in months (IQR)2.8 (1.4−3.3)4.4 (3.1−5.3)3.2 (2.2−4.5)Clinical Benefit Rate (95% CI)43% (22−66)63% (41−81)44% (31−59)median duration in months (IQR)5.4 (4.2−6.7)8.1 (6.3−10.8)6.9 (5.4−10.3)median PFS in months (95% CI)4.2 (3−5.4)6.2 (2.9−8.1)4.6 (3.2–5.7)median OS in months (95% CI)10.4 (7.7−18.4)18 (12.2–27.2)16.8 (10.6–18.4)Landmark OS estimate12 months (95% CI)40% (19−60)75% (53−88)60% (45−72)18 months (95% CI)30% (12−50)50% (29−68)42% (29−55)24 months (95% CI)20% (6−39)33% (16−52)25% (14−37)CI: confidence interval; IQR: interquartile range; OS: overall survival; PFS: progression free survival

Citation Format: Peter A. Kaufman, Sonia Pernas, Miguel Martin, Marta Gil-Martin, Patricia Gomez Pardo, Sara Lopez-Tarruella, Luis Manso, Eva Ciruelos, Jose Alejandro Perez-Fidalgo, Cristina Hernando, Foluso O Ademuyiwa, Katherine Weilbaecher, Ingrid A Mayer, Timothy J. Pluard, Maria Martinez Garcia, Francois Ringeisen, Daniela Schmitter, Javier Cortes. Balixafortide (a CXCR4 antagonist) plus eribulin in HER2 negative metastatic breast cancer: Final analysis from the Phase 1 single arm trial [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS12-13.

Abstract PD11-05: Diabetes decreases overall survival in women with breast cancer in the southern community cohort study

Background:Factors contributing to breast cancer survival disparities in underrepresented racial and ethnic groups and low-income populations are poorly understood as few clinical trials and population based studies have included these underserved populations. The Southern Community Cohort Study (SCCS), a prospective cohort of underserved, low-income adults with high representation of Black participants, provides a unique opportunity to evaluate such disparities in cancer outcomes. A previous study utilizing SCCS data found no evidence of increased breast cancer risk among women with diabetes in this population. The purpose of this study was to evaluate the association of diabetes with overall survival in women with breast cancer in the SCCS.

Methods:The SCCS enrolled approximately 86,000 participants aged 40-79 from 12 southeastern states between 2002-2009, 86% of whom were enrolled at Community Health Centers. This analysis includes women diagnosed with incident localized breast cancers identified through annual cohort linkage with 12 state cancer registries. Demographic data including participant age at breast cancer diagnosis, self-reported history of diabetes (patient answered yes to “has a doctor ever told you that you have diabetes”), body mass index (BMI), race, household income, and insurance coverage were obtained from baseline surveys, cancer type and stage data from state cancer registries, and survival data from death registries. Survival time was defined as the number of months between initial breast cancer diagnosis and death from any cause. Descriptive characteristics including mean (standard deviation) or number (%) were used to summarize demographics. We used Pearson Chi-squared analysis to examine the association between diabetes and overall survival. Multivariable Cox proportional hazards regression was used to evaluate overall survival and diabetes, adjusting for covariates including age (continuous), race, BMI (categorical by WHO classifications), household income (binary – annual income &lt;$25,000, annual income &gt;=$25,000), insurance coverage, cancer subtype, and cancer stage).

Results:We identified a total of 1,347 women diagnosed with breast cancer. Of these, 1,016 were diagnosed with localized disease (stage 1-3) and comprised our analytic sample. Difference in denominators reflects missing data. The women were predominantly Black (667/1,016, 65.6%), low income (719/1,016 annual income less than $25,000, 70.8%), and insured (Private insurance 220/763, 28.8%; Medicare 331/763, 43.4%; Medicaid 178/763, 23.3%). Average age at diagnosis was 60.7 years (SD 9.1, IQR 41-88). Approximately one quarter of the patients (258/994, 26.0%) self-reported diabetes and 59.6% (605/1,016) were obese (BMI &gt;=30). The breast cancer immunohistochemistry subtypes in this cohort of women included HR+HER2- (392/564, 69.5%), HR+,HER2+ (55/564, 9.8%), HR-,HER2+ (31/564, 5.5%), and HR-HER2- (86/564, 15.3%). Women with diabetes had lower overall survival (174/258, 67.4%) than women without diabetes (587/746, 79.8%) (p&lt;0.0001). In the adjusted multivariate Cox regression model, diabetes significantly decreased overall survival in women with breast cancer, hazard ratio 1.87, 95% Confidence Interval [CI] = 1.12-3.09.

Conclusion:

In a low-income, predominantly Black population with incident localized breast cancer, decreased overall survival was observed among women diabetes compared to those without diabetes. Future studies should explore additional biological, societal, and socio-economic factors affecting survival among women with breast cancer in medically underserved minority populations.

Citation Format: Lucy B. Spalluto, Sonya Reid, Diane Haddad, Tuya Pal, Ingrid A. Mayer, Xiao-ou Shu, Maureen Sanderson, Wei Zheng, William J. Blot, Loren Lipworth. Diabetes decreases overall survival in women with breast cancer in the southern community cohort study [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PD11-05.

Racial/Ethnic Disparities in All-Cause Mortality among Patients Diagnosed with Triple-Negative Breast Cancer

It is unclear whether racial/ethnic disparities in triple-negative breast cancer (TNBC) mortality remain after accounting for clinical characteristics, treatment, and access-to-care-related factors. In this study, women with a primary diagnosis of TNBC during 2010-2014 were identified from the National Cancer Database. Hazard ratios (HR) and 95% confidence intervals (CI) for 3- and 5-year all-cause mortality associated with race/ethnicity were estimated using Cox proportional hazards models with stepwise adjustments for age, clinical characteristics, treatment, and access-to-care-related factors. Of 78,708 patients, non-Hispanic (NH) black women had the lowest 3-year overall survival rates (79.4%), followed by NH-whites (83.1%), Hispanics (86.0%), and Asians (87.1%). After adjustment for clinical characteristics, NH-blacks had a 12% higher risk of dying 3 years post-diagnosis (HR, 1.12; 95% CI, 1.07-1.17), whereas Hispanics and Asians had a 24% (HR, 0.76; 95% CI, 0.70-0.83) and 17% (HR, 0.83; 95% CI, 0.73-0.94) lower risk than their NH-white counterparts. The black-white disparity became non-significant after combined adjustment for treatment and access-to-care-related factors (HR, 1.04; 95% CI, 0.99-1.09), whereas the white-Hispanic and white-Asian differences remained. Stratified analyses revealed that among women aged less than or equal to 50 with stage III cancer, the elevated risk among NH-blacks persisted (HR, 1.20; 95% CI, 1.04-1.39) after full adjustments. Similar results were seen for 5-year mortality. Overall, clinical characteristics, treatment, and access-to-care-related factors accounted for most of the white-black differences in all-cause mortality of TNBC but explained little about Hispanic- and Asian-white differences. SIGNIFICANCE: These findings highlight the need for equal healthcare to mitigate the black-white disparity and for investigations of contributors beyond healthcare for lower mortality among Asians and Hispanics.

Abstract PD9-06: Peripheral blood gene signatures predict response to neoadjuvant chemotherapy in breast cancer patients

Purpose: Neoadjuvant chemotherapy (NAC), the standard of care for a subset of breast cancer patients, is known to have immunologic effects. With emerging data showing improved response rates with anti-PD-1/PD-L1 immunotherapy in combination with chemotherapy, the effects of NAC on systemic and local anti-tumor immunity require further study. Biomarkers of anti-tumor immunity are needed to identify which patients are most likely to respond to immunotherapy. Our previous work has shown that changes in the peripheral blood can be observed over the course of NAC for breast cancer. Peripheral blood biomarkers are attractive because of the relative ease of sampling compared to site of disease. Residual cancer burden (RCB) is a useful surrogate marker of long-term prognosis, as patients who experience a pathologic complete response (pCR) have better outcomes than those with residual disease (RD). Methods: We previously identified an 8 gene signature of cytotoxicity, derived from single cell RNA sequencing of PD-1Hi CD8+ T cells, which are enriched for tumor-reactive T cells. Using a custom NanoString panel, we tested expression of this gene signature in whole blood collected prior to definitive surgery in 88 breast cancer patients (TNBC, n=21; HER2+, n=17; ER+, n= 54; PR+, n=53) across two cohorts (VUMC, n=58; DFCI, n=30), 64 of whom had received NAC (pCR, n=11; RD, n=53). We further investigated peripheral blood gene expression using RNA sequencing (n=58; 34 post-NAC, 24 untreated). Results: In two cohorts of breast cancer patients, expression of the 8 gene signature (FGFBP2 + GNLY + GZMB + GZMH + NKG7 + LAG3 + PDCD1 - HLA-G) was highest in patients with RD who experienced a recurrence within three years compared to those with pCR (p&lt;0.01) or those with the highest RCB (RCB III) compared to those with RCB 0/I/II who did not have a recurrence with three years (p&lt;0.05). RNA sequencing showed higher expression of interferon alpha, interferon gamma, and complement gene sets in patients experiencing a pCR compared to those with RD by gene set enrichment analysis (FDR-corrected q-values &lt; 0.05). Conclusions: Expression of immune-related genes in the peripheral blood may predict response to NAC in breast cancer patients and be a useful biomarker for those who would benefit from additional therapies. These results will be further tested in a large cohort of longitudinal samples from breast cancer patients receiving NAC alone or in combination with pembrolizumab from the I-SPY-2 trial, to determine whether peripheral blood gene signatures can predict response to immunotherapy in breast cancer.

Citation Format: Margaret L Axelrod, Paula I Gonzalez-Ericsson, Xiaopeng Sun, Riley E Bergman, Joshua Donaldson, Sara M Tolaney, Ian E Krop, Ana C Garrido-Castro, Melinda E. Sanders, Ingrid A Mayer, Justin M Balko. Peripheral blood gene signatures predict response to neoadjuvant chemotherapy in breast cancer patients [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PD9-06.

Alpelisib plus fulvestrant for PIK3CA-mutated, hormone receptor-positive, human epidermal growth factor receptor-2-negative advanced breast cancer: final overall survival results from SOLAR-1

BACKGROUND

Activation of the phosphatidylinositol-3-kinase (PI3K) pathway via PIK3CA mutations occurs in 28%-46% of hormone receptor-positive (HR+), human epidermal growth factor receptor-2-negative (HER2-) advanced breast cancers (ABCs) and is associated with poor prognosis. The SOLAR-1 trial showed that the addition of alpelisib to fulvestrant treatment provided statistically significant and clinically meaningful progression-free survival (PFS) benefit in PIK3CA-mutated, HR+, HER2- ABC.

PATIENTS AND METHODS

Men and postmenopausal women with HR+, HER2- ABC whose disease progressed on or after aromatase inhibitor (AI) were randomized 1 : 1 to receive alpelisib (300 mg/day) plus fulvestrant (500 mg every 28 days and once on day 15) or placebo plus fulvestrant. Overall survival (OS) in the PIK3CA-mutant cohort was evaluated by Kaplan-Meier methodology and a one-sided stratified log-rank test was carried out with an O'Brien-Fleming efficacy boundary of P ≤ 0.0161.

RESULTS

In the PIK3CA-mutated cohort (n = 341), median OS [95% confidence interval (CI)] was 39.3 months (34.1-44.9) for alpelisib-fulvestrant and 31.4 months (26.8-41.3) for placebo-fulvestrant [hazard ratio (HR) = 0.86 (95% CI, 0.64-1.15; P = 0.15)]. OS results did not cross the prespecified efficacy boundary. Median OS (95% CI) in patients with lung and/or liver metastases was 37.2 months (28.7-43.6) and 22.8 months (19.0-26.8) in the alpelisib-fulvestrant and placebo-fulvestrant arms, respectively [HR = 0.68 (0.46-1.00)]. Median times to chemotherapy (95% CI) for the alpelisib-fulvestrant and placebo-fulvestrant arms were 23.3 months (15.2-28.4) and 14.8 months (10.5-22.6), respectively [HR = 0.72 (0.54-0.95)]. No new safety signals were observed with longer follow-up.

CONCLUSIONS

Although the analysis did not cross the prespecified boundary for statistical significance, there was a 7.9-month numeric improvement in median OS when alpelisib was added to fulvestrant treatment of patients with PIK3CA-mutated, HR+, HER2- ABC. Overall, these results further support the statistically significant prolongation of PFS observed with alpelisib plus fulvestrant in this population, which has a poor prognosis due to a PIK3CA mutation. CLINICALTRIALS.

GOV ID

NCT02437318.

At the Bedside: Profiling and treating patients with CXCR4-expressing cancers

The chemokine receptor, C-X-C chemokine receptor type 4 (CXCR4) and its ligand, C-X-C motif chemokine 12, are key mediators of hematopoietic cell trafficking. Their roles in the proliferation and metastasis of tumor cells, induction of angiogenesis, and invasive tumor growth have been recognized for over 2 decades. CXCR4 is a promising target for imaging and therapy of both hematologic and solid tumors. To date, Sanofi Genzyme's plerixafor is the only marketed CXCR4 inhibitor (i.e., Food and Drug Administration-approved in 2008 for stem cell mobilization). However, several new CXCR4 inhibitors are now being investigated as potential therapies for a variety of fluid and solid tumors. These small molecules, peptides, and Abs include balixafortide (POL6326, Polyphor), mavorixafor (X4P-001, X4 Pharmaceuticals), motixafortide (BL-8040, BioLineRx), LY2510924 (Eli Lilly), and ulocuplumab (Bristol-Myers Squibb). Early clinical evidence has been encouraging, for example, with motixafortide and balixafortide, and the CXCR4 inhibitors appear to be generally safe and well tolerated. Molecular imaging is increasingly being used for effective patient selection before, or early during CXCR4 inhibitor treatment. The use of radiolabeled theranostics that combine diagnostics and therapeutics is an additional intriguing approach. The current status and future directions for radioimaging and treating patients with CXCR4-expressing hematologic and solid malignancies are reviewed. See related review - At the Bench: Pre-Clinical Evidence for Multiple Functions of CXCR4 in Cancer. J. Leukoc. Biol. xx: xx-xx; 2020.

Hydroxychloroquine as pre-exposure prophylaxis for COVID-19 in healthcare workers: a randomized trial

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a rapidly emerging virus causing the ongoing Covid-19 pandemic with no known effective prophylaxis. We investigated whether hydroxychloroquine could prevent SARS CoV-2 in healthcare workers at high-risk of exposure.

METHODS

We conducted a randomized, double-blind, placebo-controlled clinical trial of healthcare workers with ongoing exposure to persons with Covid-19, including those working in emergency departments, intensive care units, Covid-19 hospital wards, and first responders. Participants across the United States and in the Canadian province of Manitoba were randomized to hydroxychloroquine 400mg once weekly or twice weekly for 12 weeks. The primary endpoint was confirmed or probable Covid-19-compatible illness. We measured hydroxychloroquine whole blood concentrations.

RESULTS

We enrolled 1483 healthcare workers, of which 79% reported performing aerosol-generating procedures. The incidence of Covid-19 (laboratory-confirmed or symptomatic compatible illness) was 0.27 events per person-year with once-weekly and 0.28 events per person-year with twice-weekly hydroxychloroquine compared with 0.38 events per person-year with placebo. For once weekly hydroxychloroquine prophylaxis, the hazard ratio was 0.72 (95%CI 0.44 to 1.16; P=0.18) and for twice weekly was 0.74 (95%CI 0.46 to 1.19; P=0.22) as compared with placebo. Median hydroxychloroquine concentrations in whole blood were 98 ng/mL (IQR, 82-120) with once-weekly and 200 ng/mL (IQR, 159-258) with twice-weekly dosing. Hydroxychloroquine concentrations did not differ between participants who developed Covid-19 (154 ng/mL) versus participants without Covid-19 (133 ng/mL; P=0.08).

CONCLUSIONS

Pre-exposure prophylaxis with hydroxychloroquine once or twice weekly did not significantly reduce laboratory-confirmed Covid-19 or Covid-19-compatible illness among healthcare workers.

Sacituzumab govitecan in previously treated hormone receptor-positive/HER2-negative metastatic breast cancer: final results from a phase I/II, single-arm, basket trial

BACKGROUND

Trophoblast cell-surface antigen-2 (Trop-2) is expressed in epithelial cancers, including hormone receptor-positive (HR+) metastatic breast cancer (mBC). Sacituzumab govitecan (SG; Trodelvy®) is an antibody-drug conjugate composed of a humanized anti-Trop-2 monoclonal antibody coupled to SN-38 at a high drug-to-antibody ratio via a unique hydrolyzable linker that delivers SN-38 intracellularly and in the tumor microenvironment. SG was granted accelerated FDA approval for metastatic triple-negative BC treatment in April 2020.

PATIENTS AND METHODS

We analyzed a prespecified subpopulation of patients with HR+/human epidermal growth factor receptor 2-negative (HER2-) HR+/HER2- mBC from the phase I/II, single-arm trial (NCT01631552), who received intravenous SG (10 mg/kg) and whose disease progressed on endocrine-based therapy and at least one prior chemotherapy for mBC. End points included objective response rate (ORR; RECIST version 1.1) assessed locally, duration of response (DOR), clinical benefit rate, progression-free survival (PFS), overall survival (OS), and safety.

RESULTS

Fifty-four women were enrolled between 13 February 2015 and 1 June 2017. Median (range) age was 54 (33-79) years and all received at least two prior lines of therapy for mBC. At data cut-off (1 March 2019), 12 patients were still alive. Key grade ≥3 treatment-related toxicities included neutropenia (50.0%), anemia (11.1%), and diarrhea (7.4%). Two patients discontinued treatment due to treatment-related adverse events. No treatment-related deaths occurred. At a median follow-up of 11.5 months, the ORR was 31.5% [95% confidence interval (CI), 19.5%-45.6%; 17 partial responses]; median DOR was 8.7 months (95% CI 3.7-12.7), median PFS was 5.5 months (95% CI 3.6-7.6), and median OS was 12 months (95% CI 9.0-18.2).

CONCLUSIONS

SG shows encouraging activity in patients with pretreated HR+/HER2- mBC and a predictable, manageable safety profile. Further evaluation in a randomized phase III trial (TROPiCS-02) is ongoing (NCT03901339).

TRIAL REGISTRATION

ClinicalTrials.gov NCT01631552; https://clinicaltrials.gov/ct2/show/NCT01631552.

Radiotherapy after breast-conserving surgery for elderly patients with early-stage breast cancer: A national registry-based study

Considerable controversies exist regarding whether elderly patients with early-stage breast cancer receiving breast-conserving surgery (BCS) should forgo radiotherapy. We utilized the National Cancer Database to analyze data of 115 516 women aged ≥70 years, treated with BCS for T1-2N0-1M0 breast cancer between 2004 and 2014. Multivariable Cox proportional hazards model was used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for mortality 3, 5 and 10 years after 90 days of BCS associated with radiotherapy. Patients who received no radiotherapy had a higher mortality rate than those who received radiotherapy (5-year survival rate: 71.2% vs 83.8%), with multivariable-adjusted HRs of 1.65 (95% CI: 1.57-1.72) for 3-year mortality, 1.53 (1.47-1.58) for 5-year mortality and 1.43 (1.39-1.48) for 10-year mortality. The association held even for patients ≥90 years. This association was observed in all strata by reasons for radiotherapy omission, receipt of endocrine therapy or chemotherapy, calendar period and other clinical characteristics, with 40% to 65% increased 5-year mortality for patients without radiotherapy. This positive association persisted when analyses were restricted to patients with T1N0 and estrogen-receptor-positive disease who had received endocrine therapy (5-year mortality: HR 1.47 [1.39-1.57]) and in propensity score weighted analyses. Our study shows, in routine practice, elderly patients who received no post-BCS radiotherapy had higher total mortality than those who received radiotherapy. These findings suggest that the current recommendation of omission of post-BCS radiotherapy for elderly women with early-stage breast cancer may need to be reconsidered, particularly for those without contraindication.

Changes in Peripheral and Local Tumor Immunity after Neoadjuvant Chemotherapy Reshape Clinical Outcomes in Patients with Breast Cancer

PURPOSE

The recent approval of anti-programmed death-ligand 1 immunotherapy in combination with nab-paclitaxel for metastatic triple-negative breast cancer (TNBC) highlights the need to understand the role of chemotherapy in modulating the tumor immune microenvironment (TIME).

EXPERIMENTAL DESIGN

We examined immune-related gene expression patterns before and after neoadjuvant chemotherapy (NAC) in a series of 83 breast tumors, including 44 TNBCs, from patients with residual disease (RD). Changes in gene expression patterns in the TIME were tested for association with recurrence-free (RFS) and overall survival (OS). In addition, we sought to characterize the systemic effects of NAC through single-cell analysis (RNAseq and cytokine secretion) of programmed death-1-high (PD-1^HI) CD8⁺ peripheral T cells and examination of a cytolytic gene signature in whole blood.

RESULTS

In non-TNBC, no change in expression of any single gene was associated with RFS or OS, while in TNBC upregulation of multiple immune-related genes and gene sets were associated with improved long-term outcome. High cytotoxic T-cell signatures present in the peripheral blood of patients with breast cancer at surgery were associated with persistent disease and recurrence, suggesting active antitumor immunity that may indicate ongoing disease burden.

CONCLUSIONS

We have characterized the effects of NAC on the TIME, finding that TNBC is uniquely sensitive to the immunologic effects of NAC, and local increases in immune genes/sets are associated with improved outcomes. However, expression of cytotoxic genes in the peripheral blood, as opposed to the TIME, may be a minimally invasive biomarker of persistent micrometastatic disease ultimately leading to recurrence.

Capivasertib, an AKT Kinase Inhibitor, as Monotherapy or in Combination with Fulvestrant in Patients with AKT1 E17K-Mutant, ER-Positive Metastatic Breast Cancer

PURPOSE

The activating mutation AKT1 E17K occurs in approximately 7% of estrogen receptor-positive (ER+) metastatic breast cancer (MBC). We report, from a multipart, first-in-human, phase I study (NCT01226316), tolerability and activity of capivasertib, an oral AKT inhibitor, as monotherapy or combined with fulvestrant in expansion cohorts of patients with AKT1 E17K-mutant ER+ MBC.

PATIENTS AND METHODS

Patients with an AKT1 E17K mutation, detected by local (next-generation sequencing) or central (plasma-based BEAMing) testing, received capivasertib 480 mg twice daily, 4 days on, 3 days off, weekly or 400 mg twice daily combined with fulvestrant at the labeled dose. Study endpoints included safety, objective response rate (ORR; RECIST v1.1), progression-free survival (PFS), and clinical benefit rate at 24 weeks (CBR24). Biomarker analyses were conducted in the combination cohort.

RESULTS

From October 2013 to August 2018, 63 heavily pretreated patients received capivasertib (20 monotherapy, 43 combination). ORR was 20% with monotherapy, and within the combination cohort was 36% in fulvestrant-pretreated and 20% in fulvestrant-naïve patients, although the latter group may have had more aggressive disease at baseline. AKT1 E17K mutations were detectable in plasma by BEAMing (95%, 41/43), droplet digital PCR (80%, 33/41), and next-generation sequencing (76%, 31/41). A ≥50% decrease in AKT1 E17K at cycle 2 day 1 was associated with improved PFS. Combination therapy appeared more tolerable than monotherapy [most frequent grade ≥3 adverse events: rash (9% vs. 20%), hyperglycemia (5% vs. 30%), diarrhea (5% vs. 10%)].

CONCLUSIONS

Capivasertib demonstrated clinically meaningful activity in heavily pretreated patients with AKT1 E17K-mutant ER+ MBC, including those with prior disease progression on fulvestrant. Tolerability and activity appeared improved by the combination.