Tumor-Infiltrating Lymphocytes Refine Outcomes in Triple-Negative Breast Cancer Treated with Anthracycline-Free Neoadjuvant Chemotherapy

PURPOSE

Stromal tumor-infiltrating lymphocytes (sTIL) are associated with pathologic complete response (pCR) and long-term outcomes for triple-negative breast cancer (TNBC) in the setting of anthracycline-based chemotherapy. The impact of sTILs on refining outcomes beyond prognostic information provided by pCR in anthracycline-free neoadjuvant chemotherapy (NAC) is not known.

EXPERIMENTAL DESIGN

This is a pooled analysis of two studies where patients with stage I (T>1 cm)-III TNBC received carboplatin (AUC 6) plus docetaxel (75 mg/m2; CbD) NAC. sTILs were evaluated centrally on pre-treatment hematoxylin and eosin slides using standard criteria. Cox regression analysis was used to examine the effect of variables on event-free survival (EFS) and overall survival (OS).

RESULTS

Among 474 patients, 44% had node-positive disease. Median sTILs were 5% (range, 1%-95%), and 32% of patients had ≥30% sTILs. pCR rate was 51%. On multivariable analysis, T stage (OR, 2.08; P = 0.007), nodal status (OR, 1.64; P = 0.035), and sTILs (OR, 1.10; P = 0.011) were associated with pCR. On multivariate analysis, nodal status (HR, 0.46; P = 0.008), pCR (HR, 0.20; P < 0.001), and sTILs (HR, 0.95; P = 0.049) were associated with OS. At 30% cut-point, sTILs stratified outcomes in stage III disease, with 5-year OS 86% versus 57% in ≥30% versus <30% sTILs (HR, 0.29; P = 0.014), and numeric trend in stage II, with 5-year OS 93% versus 89% in ≥30% versus <30% sTILs (HR, 0.55; P = 0.179). Among stage II-III patients with pCR, EFS was better in those with ≥30% sTILs (HR, 0.16; P, 0.047).

CONCLUSIONS

sTILs density was an independent predictor of OS beyond clinicopathologic features and pathologic response in patients with TNBC treated with anthracycline-free CbD chemotherapy. Notably, sTILs density stratified outcomes beyond tumor-node-metastasis (TNM) stage and pathologic response. These findings highlight the role of sTILs in patient selection and stratification for neo/adjuvant escalation and de-escalation strategies.

Clinical and Biomarker Findings of Neoadjuvant Pembrolizumab and Carboplatin Plus Docetaxel in Triple-Negative Breast Cancer: NeoPACT Phase 2 Clinical Trial

Importance

Addition of pembrolizumab to anthracycline-based chemotherapy improves pathologic complete response (pCR) and event-free survival (EFS) in triple-negative breast cancer (TNBC). The efficacy of anthracycline-free chemoimmunotherapy in TNBC has not been assessed.

Objective

To assess the efficacy of the anthracycline-free neoadjuvant regimen of carboplatin and docetaxel plus pembrolizumab in TNBC.

Design, Setting, and Participants

This was an open-label phase 2 clinical trial including a single group of patients with stage I to III TNBC enrolled at 2 sites who received neoadjuvant carboplatin and docetaxel plus pembrolizumab every 21 days for 6 cycles. Participants were enrolled from 2018 to 2022.

Intervention or Exposure

Carboplatin (with an area under the free carboplatin plasma concentration vs time curve of 6) and docetaxel (75 mg/m2) plus pembrolizumab (200 mg) every 21 days for 6 cycles. Myeloid growth factor support was administered with all cycles.

Main Outcomes and Measures

Primary end point was pathologic complete response (pCR) defined as no evidence of invasive tumor in breast and axilla. The secondary end points were residual cancer burden, EFS, toxicity, and immune biomarkers. RNA isolated from pretreatment tumor tissue was subjected to next-generation sequencing. Specimens were classified as positive or negative for the 44-gene DNA damage immune response (DDIR) signature and for the 27-gene tumor immune microenvironment (TIM; DetermaIO) signature using predefined cutoffs. Stromal tumor-infiltrating lymphocytes (sTILs) were evaluated using standard criteria. Programmed cell death-ligand 1 (PD-L1) testing was performed using a standard immunohistochemical assay.

Results

Among the eligible study population of 115 female patients (median [range] age, 50 [27-70] years) who enrolled from September 2018 to January 2022, 39% had node-positive disease. pCR and residual cancer burden 0 + 1 rates were 58% (95% CI, 48%-67%) and 69% (95% CI, 60%-78%), respectively. Grade 3 or higher immune-mediated adverse events were observed in 3.5% of patients. sTILs, PD-L1, DDIR, and TIM were each predictive of pCR in multivariable analyses. The areas under curve for pCR were 0.719, 0.740, 0.699, and 0.715 for sTILs, PD-L1, DDIR, and TIM, respectively. Estimated 3-year EFS was 86% in all patients; 98% in pCR group and 68% in no-pCR group.

Conclusions and Relevance

The findings of the phase 2 clinical trial indicate that neoadjuvant carboplatin and docetaxel plus pembrolizumab shows encouraging pCR and 3-year EFS. The regimen was well tolerated, and immune enrichment as identified by various biomarkers was independently predictive of pCR. These results provide data on an alternative anthracycline-free chemoimmunotherapy regimen for patients who are not eligible for anthracycline-based regimens and support further evaluation of this regimen as a chemotherapy de-escalation strategy in randomized studies for TNBC.

Trial Registration

ClinicalTrials.gov Identifier: NCT03639948.

ctDNA and residual cancer burden are prognostic in triple-negative breast cancer patients with residual disease

Triple-negative breast cancer (TNBC) patients with residual disease (RD) after neoadjuvant systemic therapy (NAST) are at high risk for recurrence. Biomarkers to risk-stratify patients with RD could help individualize adjuvant therapy and inform future adjuvant therapy trials. We aim to investigate the impact of circulating tumor DNA (ctDNA) status and residual cancer burden (RCB) class on outcomes in TNBC patients with RD. We analyze end-of-treatment ctDNA status in 80 TNBC patients with residual disease who are enrolled in a prospective multisite registry. Among 80 patients, 33% are ctDNA positive (ctDNA+) and RCB class distribution is RCB-I = 26%, RCB-II = 49%, RCB-III = 18% and 7% unknown. ctDNA status is associated with RCB status, with 14%, 31%, and 57% of patients within RCB-I, -II, and -III classes demonstrating ctDNA+ status (P = 0.028). ctDNA+ status is associated with inferior 3-year EFS (48% vs. 82%, P < 0.001) and OS (50% vs. 86%, P = 0.002). ctDNA+ status predicts inferior 3-year EFS among RCB-II patients (65% vs. 87%, P = 0.044) and shows a trend for inferior EFS among RCB-III patients (13% vs. 40%, P = 0.081). On multivariate analysis accounting for T stage and nodal status, RCB class and ctDNA status independently predict EFS (HR = 5.16, P = 0.016 for RCB class; HR = 3.71, P = 0.020 for ctDNA status). End-of-treatment ctDNA is detectable in one-third of TNBC patients with residual disease after NAST. ctDNA status and RCB are independently prognostic in this setting.

Abstract PD1-06: Black patients with triple negative breast cancer (TNBC) have enriched stromal tumor infiltrating lymphocytes (sTILs) and receive preferential benefit from neoadjuvant immunotherapy

Introduction TNBC is overrepresented in Black women, and Black patients with TNBC have worse clinical outcomes compared to non-Black patients. This disparity likely results from racial differences in clinical, biological, and demographic features of TNBC and social determinants of health. Neoadjuvant chemoimmunotherapy is current standard of care for high-risk TNBC. However, Black patients have been poorly represented in immunotherapy TNBC trials, making it difficult to assess comparative efficacy of immunotherapy in Black patients. Methods We utilized two TNBC neoadjuvant trials to assess racial differences in the tumor immune microenvironment composition and evaluate impact of race on response to chemotherapy vs chemoimmunotherapy. NeoSTOP trial (NCT02413320) randomized 100 stage I-III TNBC patients to receive neoadjuvant carboplatin/paclitaxel + doxorubicin/cyclophosphamide (CbP+AC) or carboplatin/docetaxel (CbD). NeoPACT trial (NCT03639948) enrolled 120 patients with stage I-III TNBC who received neoadjuvant CbD + pembrolizumab (CbD+P). sTILs were centrally quantified, and RNA extracted from pretreatment tissue was subjected to next-generation sequencing. Relative leukocyte fractions were computed by CIBERSORTx. Factors were tested as predictors of pathologic complete response (pCR) using logistic regression analysis. Event-free survival (EFS) was estimated by the Kaplan-Meier method and compared between groups by log-rank test, followed by Cox regression analysis. Results The study population includes 197 patients with known race, sTILs, and gene expression data (84 patients from NeoSTOP, 113 from NeoPACT). 15/84 (18%) patients in NeoSTOP and 20/113 (18%) patients in NeoPACT self-reported Black race. There was no significant difference in age, T or N stage, or germline BRCA1/2 mutation status by race in either study. Black patients had significantly higher sTILs than non-Black patients (median 40% vs 15%, P=0.048) and were more likely to have ≥20% sTILs than non-Black patients (66% vs 44%, P=0.026). There was no significant difference in pCR by race in NeoSTOP (OR=0.60, 95% CI 0.19-1.84, P=0.37; pCR 47% for Black vs 59% for non-Black). In contrast, in NeoPACT, Black patients had a significantly higher pCR compared to non-Black patients (OR=3.27, 95% CI 1.01-10.64, P=0.049; pCR 79% for Black vs 53% for non-Black). In NeoSTOP, EFS was similar for Black and non-Black patients (3-year EFS 92% and 94%, respectively, HR=0.88, 95% CI 0.11-7.28, P=0.90). In NeoPACT, EFS was numerically higher in Black vs non-Black patients (3-year EFS 93% and 81%, respectively, HR=0.43, 95% CI 0.05-3.36, P=0.40); NeoPACT survival follow-up is ongoing at the time of this report. On CIBERSORTx analysis, Black patients had relative depletion of immunosuppressive pro-tumorigenic M2 macrophages (P=0.005) and CD4+ memory resting T cells (P=0.021) compared to non-Black patients. Conclusions Compared to non-Black patients, Black patients with TNBC are more likely to have immune-enriched tumors with lower relative abundance of immunosuppressive leukocytes. These findings suggest potential for higher relative magnitude of benefit from checkpoint inhibitor therapy in Black compared to non-Black patients. Supporting this biological hypothesis, we noted that Black and non-Black patients had equivalent rates of pCR with neoadjuvant chemotherapy; however, pCR rate among Black patients was significantly higher than in non-Black patients when treated with neoadjuvant chemoimmunotherapy. These findings should be confirmed in other studies and can optimize utilization of neoadjuvant chemoimmunotherapy. Our findings also underscore the importance of efforts to address disparity in access and use of immunotherapy in Black patients.

Citation Format: Shane R. Stecklein, Rachel Yoder, Roberto Salgado, Joshua M. Staley, Anne O’Dea, Lauren Nye, Manana Elia, Deepti Satelli, Gregory Crane, Richard McKittrick, Andrew K. Godwin, Qamar Khan, Priyanka Sharma. Black patients with triple negative breast cancer (TNBC) have enriched stromal tumor infiltrating lymphocytes (sTILs) and receive preferential benefit from neoadjuvant immunotherapy [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD1-06.

Abstract PD11-07: PD11-07 Association of TNBC-DX scores with outcomes in triple-negative breast cancer (TNBC) treated with neoadjuvant pembrolizumab and chemotherapy: a correlative analysis from NeoPACT and NeoSTOP trials

Introduction: The TNBC-DX risk score includes the 14-gene immunoglobulin (IGG) immune signature, tumor size, and nodal status and has shown prognostic value for survival in early-stage TNBC (B. Conte et al., ESMO Breast 2021). However, currently unknown are the value of the TNBC-DX risk score and IGG immune signature in 1) predicting pathologic complete response (pCR) following neoadjuvant therapy, and 2) predicting outcomes the context of neoadjuvant anti-PD1 treatment. Here, we assessed the IGG signature and the TNBC-DX risk score in patients with TNBC treated with neoadjuvant chemoimmunotherapy (NeoPACT; NCT03639948) and neoadjuvant chemotherapy without immunotherapy (NeoSTOP; NCT02413320). Methods: NeoPACT trial enrolled 120 patients with stage I-III TNBC who received carboplatin (AUC 6) + docetaxel (75 mg/m2) + pembrolizumab (200 mg) every 21 days x 6 cycles. NeoSTOP randomized 100 patients with stage I-III TNBC to two chemotherapy regimens; Arm B of NeoSTOP was included in this correlative study as the chemotherapy regimen was identical to NeoPACT. RNA isolated from pretreatment tumor tissue was subjected to next-generation sequencing. The 14-gene IGG immune signature and TNBC-DX risk score were calculated in silico as previously described. Evaluation of stromal tumor-infiltrating lymphocytes (sTILs) was performed as previously described. Markers were tested for prediction of pCR. Logistic regression analysis was used to examine the effect of multiple variables. Event-free survival (EFS) curves were assessed by the Kaplan-Meier method and groups compared by the log-rank test, followed by Cox regression analysis. Results: In this analysis, 112 patients were treated with chemoimmunotherapy on NeoPACT (node-positive = 38%, pCR rate = 58%). In the NeoPACT trial, the 14-gene IGG signature (as a continuous variable) was significantly associated with improved pCR (odds ratio [OR]=1.105, 95% CI 1.019-1.197, P=0.015 for every 0.2 increment). The pCR rates in IGG-high (≥ median) and IGG-low (&lt; median) groups were 71% and 44%, respectively (OR=3.152, 95% CI 1.420-6.996, P=0.005). In terms of EFS, the 14-gene IGG signature was not prognostic (hazard ratio [HR]=0.507, 95% CI 0.148-1.735, p=0.269). In contrast, TNBC-DX risk score was strongly associated with EFS (HR=5.684, 95% CI 1.226-26.356, P=0.012), even when adjusted for sTILs and pCR status (HR=8.415, 95% CI 1.054-67.169, P=0.044). Estimated 3-year EFS rates in TNBC-DX high and low risk groups (above and below median) were 77% and 89%, respectively (P=0.012). In 43 NeoSTOP patients treated with neoadjuvant chemotherapy only (node-positive = 33%, pCR rate = 53%), no association of IGG signature with pCR or TNBC-DX score with EFS was observed. Finally, we observed a moderate correlation between IGG signature and sTILs in both trial datasets combined (r=0.642, P&lt; 0.001). Conclusions: High expression of the 14-gene IGG immune signature in baseline pretreatment tumor samples in early-stage TNBC is significantly associated with pCR following pembrolizumab-based neoadjuvant chemotherapy. The combination of this signature with tumor burden as assessed by TNBC-DX is prognostic for long-term outcomes. Availability of biomarkers that can predict both pathological response and survival with chemoimmunotherapy can optimize this therapy, and evaluation of this biomarker in larger studies is warranted.

Citation Format: Priyanka Sharma, Shane R. Stecklein, Rachel Yoder, Joshua M. Staley, Roberto Salgado, Laia Paré, Benedetta Conte, Fara Brasó-Maristany, Anne O’Dea, Lauren Nye, Manana Elia, Deepti Satelli, Gregory Crane, Richard McKittrick, Qamar Khan, Andrew K. Godwin, Aleix Prat. PD11-07 Association of TNBC-DX scores with outcomes in triple-negative breast cancer (TNBC) treated with neoadjuvant pembrolizumab and chemotherapy: a correlative analysis from NeoPACT and NeoSTOP trials [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD11-07.

Impact of low versus negative estrogen/progesterone receptor status on clinico-pathologic characteristics and survival outcomes in HER2-negative breast cancer

Triple-negative breast cancer (TNBC) is classically defined by estrogen receptor (ER) and progesterone receptor (PR) immunohistochemistry expression <1% and absence of HER2 amplification/overexpression. HER2-negative breast cancer with low ER/PR expression (1–10%) has a gene expression profile similar to TNBC; however, real-world treatment patterns, chemotherapy response, endocrine therapy benefit, and survival outcomes for the Low-ER group are not well known. 516 patients with stage I-III HER2-negative breast cancer and ER/PR expression ≤10% who were enrolled in a multisite prospective registry between 2011 and 2019 were categorized on the basis of ER/PR expression. TNBC (ER and PR < 1%) and Low-ER (ER and/or PR 1–10%) groups comprised 87.4% (n = 451) and 12.6% (n = 65) of patients, respectively. Demographic, clinical, and treatment characteristics, including prevalence of germline BRCA1/2 mutation, racial and ethnic distribution, and chemotherapy use were not different between TNBC and Low-ER groups. No difference was observed in recurrence-free survival (RFS) and overall survival (OS) between TNBC and Low-ER groups (3-year RFS 82.5% versus 82.4%, respectively, p = 0.728; 3-year OS 88.0% versus 83.4%, respectively, p = 0.632). Among 358 patients receiving neoadjuvant chemotherapy, rates of pathologic complete response were similar for TNBC and Low-ER groups (49.2% vs 51.3%, respectively, p = 0.808). The HER2-negative Low-ER group is often excluded from TNBC clinical trials assessing novel treatments (immunotherapy and antibody-drug conjugates), thus limiting efficacy data for newer effective therapies in this group. Given that HER2-negative Low-ER disease displays clinical characteristics and outcomes similar to TNBC, inclusion of this group in TNBC clinical trials is encouraged.

Clinical and biomarker results of neoadjuvant phase II study of pembrolizumab and carboplatin plus docetaxel in triple-negative breast cancer (TNBC) (NeoPACT)

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Background: Addition of pembrolizumab to anthracycline-taxane-platinum chemotherapy improves pathologic complete response (pCR) and event free survival (EFS) in TNBC. Aim of this study was to assess the efficacy of the anthracycline free neoadjuvant regimen of pembrolizumab plus carboplatin plus docetaxel (Cb+D) in TNBC. Methods: In this multicenter study, eligible patients with stage I-III TNBC received carboplatin (AUC 6) + docetaxel (75 mg/m2) + pembrolizumab (200 mg) every 21 days x 6 cycles. The primary endpoint was pCR (no evidence of invasive tumor in breast and axilla). Secondary endpoints were residual cancer burden (RCB), EFS, toxicity, and immune response biomarkers. RNA isolated from pretreatment tumor tissue was subjected to next generation sequencing. Samples were classified as DNA Damage Immune Response (DDIR) signature and DetermaIO signature positive/negative using predefined cutoffs. Evaluation of stromal tumor infiltrating lymphocytes (sTILs) was performed using standard criteria. Results: 117 patients were enrolled from September 2018 to January 2022. 18% were African American, 39% had node positive disease, 88% had stage II/III disease and 15% had ER/PR 1-10%. Pathologic response information is available for 105 patients. pCR and RCB 0+1 rates were 60% (95% CI 51%-70%) and 71% (95% CI 62%-80%), respectively. Treatment related adverse events led to discontinuation of any trial drug in 12% of patients. Immune adverse events were observed in 28% of patients (Grade ≥3=6%). 47% of patients had sTILs ≥30%, 48% were DetermaIO positive, and 61% DDIR positive. The table describes the impact of these biomarkers on pCR and RCB. The areas under the prediction curve (AUC) for pCR were 0.660, 0.709, and 0.719 for DDIR, sTILs, and DetermaIO respectively. At a median follow up of 21 months, 2-year EFS is 88% in all patients; 98% in pCR group and 82% in no pCR group. Conclusions: Neoadjuvant pembrolizumab plus Cb+D regimen yields pCR of 60% and 2-year EFS of 88% in the absence of adjuvant pembrolizumab. The regimen was well tolerated, and no new toxicity signals were noted. Immune enrichment identified by sTILs or DetermaIO signature was associated with high pCR rates approaching or exceeding 80%. PD-L1 and additional biomarker analyses are ongoing. Clinical trial information: NCT03639948. [Table: see text]

Abstract P2-01-05: Impact of post-treatment ctDNA and residual cancer burden (RCB) on outcomes in patients with triple-negative breast cancer (TNBC) and residual disease

Introduction: Residual disease (RD) after neoadjuvant chemotherapy (NACT) is associated with high risk of recurrence in TNBC. RCB classification is prognostic in patients with RD. Recent studies show that post-NACT circulating cell-free tumor DNA (ctDNA) also provides prognostic information in patients with RD. Most TNBC patients with RD receive adjuvant therapy after surgery (chemotherapy and/or radiation), thus ctDNA status at completion of all adjuvant therapy (end of treatment, EOT) may be a better indicator of long-term prognosis. Furthermore, the impact of EOT ctDNA status on prognosis in context of RCB is of interest. Utilizing data from a prospective registry, the objective of this study was to investigate the impact of EOT ctDNA status and RCB class on outcomes in TNBC patients with RD. We hypothesized that RCB and EOT ctDNA status may provide complementary prognostic information. Methods: Study population included TNBC patients with RD post-NACT and available EOT plasma samples who were enrolled in an IRB-approved multisite prospective registry between 2011 and 2018. EOT samples were collected after completion (1-6 months) of all curative treatment (local and systemic). ctDNA was isolated and subjected to next generation sequencing (QIAseq 275-gene Human Comprehensive Cancer Panel on an Illumina NextSeq 550). Samples demonstrating pathogenic/likely pathogenic variant(s) with 3-40% allelic frequencies were considered ctDNA positive. Variants with allelic frequencies ≥40% were included in ctDNA positive status only if not present in ClinVar8/dbSNP9 as a known germline variant. The impact of EOT ctDNA status and RCB on event-free survival (EFS) and overall survival (OS) were estimated according to the Kaplan-Meier method and compared among groups by log-rank test, followed by Cox regression analysis. Results: For 47 TNBC patients with RD and available EOT plasma sample, the median age was 47 years, and 43% had node-positive disease at diagnosis. RCB class distribution was as follows: RCB I=28%, RCB II=49%, RCB III=15%, RCB unknown=8%. 45% of patients received adjuvant chemotherapy (59% with RCB II-III received adjuvant chemotherapy), and 68% received adjuvant radiation. EOT ctDNA was positive in 34% (16/47) of patients and was associated with higher T stage (p=0.012), TNM stage (p=0.033) and trend toward higher RCB class (p=0.078). ctDNA positivity rates in RCB I, II and III classes were 23%, 30% and 71%, respectively. Among all patients, 3-year EFS and OS were 71% and 73%, respectively. Table 1 provides 3-year EFS and OS by ctDNA status in all patients and by RCB class. ctDNA positive status was associated with inferior EFS and OS. Conclusion: EOT ctDNA positivity was noted in one-third of TNBC patients with residual disease and was highly prognostic, with almost half of patients with ctDNA positivity suffering an EFS event by 3 years. Patients with RCB III had very poor outcome (3-year EFS ≤20%) regardless of ctDNA status. However, in RCB classes I/II, ctDNA provided further prognostic utility, as ctDNA negative patients with RCB I/II had excellent outcomes (3-year EFS &gt;90%). These findings should be confirmed in other studies and provide insights into the role of ctDNA for patient stratification/selection in residual disease adjuvant therapy intensification trials for TNBC.

3-year EFS3-year OSAll patients: ctDNA positive vs ctDNA negative56% vs 78%, HR 3.02 (95% CI: 1.01-9.01), p=0.03856% vs 82%, HR 3.05 (95% CI: 1.02-9.13), p=0.037RCB I/II: ctDNA positive vs ctDNA negative73% vs 92%, HR 4.38, p=0.07873% vs 92%, HR 3.03, p=0.159RCB III: ctDNA positive vs ctDNA negative0% vs 20%, HR 1.67, p=0.5610% vs 20%, HR 1.30, p=0.765

Citation Format: Priyanka Sharma, Shane R Stecklein, Bruce F Kimler, Rachel Yoder, Kelsey Schwensen, Joshua M Staley, Qamar J Khan, Anne P O'Dea, Lauren E Nye, Manana Elia, Jaimie Heldstab, Trisha Home, Stephen Hyter, Kamilla Isakova, Harsh B Pathak, Andrew K Godwin. Impact of post-treatment ctDNA and residual cancer burden (RCB) on outcomes in patients with triple-negative breast cancer (TNBC) and residual disease [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 P2-01-05.

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

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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]

Abstract PS6-04: Impact of low versus negative estrogen/progesterone receptor status on clinico-pathologic characteristics and survival outcomes in HER2 negative breast cancer

Background: Triple negative breast cancer is defined by lack of expression of ER/PR (immunohistochemistry expression &lt;1%) and absence of HER2 gene amplification. However, data regarding endocrine therapy benefit in patients with low levels (1-10%) of ER/PR expression are lacking. Furthermore, gene expression studies show tremendous similarities between HER2 negative tumors with low and negative ER/PR status. Accordingly, the 2020 ASCO/CAP guideline designates that ER expression of 1-10% be reported as a distinct “ER low positive” category. Utilizing data from a prospective registry, the aim of this study was to determine the impact of low versus negative ER/PR status on clinico-pathologic characteristics and survival outcomes in patients with HER2 negative breast cancers. Methods: 516 subjects with stage I-III HER2 negative breast cancer and ER/PR IHC ≤10% were enrolled in an IRB-approved multisite prospective registry between 2011 and 2019. Demographic, clinical, pathologic, and treatment information was collected, and patients were followed for recurrence and survival. Patients were categorized according to ER/PR expression into two groups: TNBC (ER and PR &lt;1%) and Low-ER (ER and/or PR 1-10%). Recurrence free survival (RFS) and overall survival (OS) were estimated according to the Kaplan-Meier method and compared among groups by log-rank test, followed by Cox regression analysis. Results: TNBC and Low-ER groups comprised 451/516 (87.4%) and 65/516 (12.6%) patients, respectively. Demographic, clinical, pathologic, and treatment characteristics of the two groups are described in Table 1. Median follow-up was 39 months. Three-year RFS was 82% for both TNBC and Low-ER groups (p=0.70). Three-year OS was 88% and 83% for TNBC and Low-ER groups, respectively (p=0.63). Twenty percent of patients in the Low-ER group received adjuvant endocrine therapy, and endocrine therapy use did not impact outcomes in the Low-ER group (RFS: p=0.32; OS: p=0.88). On multivariate analysis, T stage, nodal status, and age significantly impacted RFS (T stage 3/4 vs 1/2, HR=2.7, p&lt;0.001; nodal status positive vs negative, HR=2.4, p&lt;0.001; age above vs below median, HR=1.8, p=0.006) and OS (T stage 3/4 vs 1/2, HR=3.6, p&lt;0.001; nodal status positive vs negative, HR=2.8, p&lt;0.001; age above vs below median, HR=1.026, p=0.01). For patients who received neoadjuvant chemotherapy, achievement of pathological complete response (pCR) was associated with superior RFS (3-year RFS of 95% and 67% in those with and without pCR, respectively, HR=0.18, p&lt;0.001). Conclusions: Patients with TNBC and Low-ER HER2 negative breast cancer present with similar clinico-pathologic characteristics, including prevalence of germline BRCA1/2 mutation. Prognosis and rate of pCR (with neo-adjuvant chemotherapy) in patients with Low-ER HER2 negative breast cancer is similar to those with TNBC. The role and efficacy of adjuvant endocrine therapy in patients with Low-ER breast cancer is unclear. These findings support consideration for inclusion of patients with Low-ER disease along with TNBC for future clinical trial eligibility and planning.

Table 1. Demographic, clinical, pathologic, and treatment characteristicsCharacteristics - N (%)All N=516TNBC (ER & PR &lt;1%) n=451Low-ER (ER or PR 1-10%) n=65pAge at diagnosis, years - median (range)53 (23-97)54 (23-97)51 (28-76)0.61RaceWhite386 (75%)335 (74%)51 (79%)0.69Black101 (20%)89 (20%)12 (19%)Asian8 (2%)8 (2%)0 (0%)Menopausal statusPre214 (42%)181 (41%)33 (51%)0.25Post295 (58%)263 (59%)32 (49%)Histological gradeI2 (0.4%)2 (0.4%)0 (0%)0.82II86 (17%)76 (17%)10 (15%)III428 (83%)373 (83%)55 (85%)T stageT1-2446 (87%)388 (87%)58 (89%)0.56T3-467 (13%)60 (13%)7 (11%)N statusPositive177 (34%)158 (35%)19 (29%)0.36Negative339 (66%)293 (65%)46 (71%)TNM stageI179 (35%)150 (33%)29 (44%)0.10II263 (51%)232 (52%)31 (48%)III74 (14%)69 (15%)5 (8%)Germline BRCA1/2 mutationYes70 (14%)64 (14%)6 (9%)0.53No357 (69%)309 (69%)48 (74%)Unknown89 (17%)78 (17%)11 (17%)ChemotherapyNeoadjuvant357 (69%)318 (71%)39 (60%)0.23Adjuvant147 (29%)123 (27%)24 (37%)None12 (2%)10 (2%)2 (3%)Surgery typeMastectomy308 (60%)275 (61%)33 (51%)0.10Lumpectomy205 (40%)173 (39%)32 (49%)Adjuvant endocrine therapyYes20 (4%)7 (2%)13 (20%)&lt;0.001No496 (96%)444 (98%)52 (80%)pCR (in patients with neoadjuvant chemotherapy, n=357)176 (49%)157 (49%)19 (49%)0.94

Citation Format: Rachel Yoder, Bruce F Kimler, Joshua M Staley, Kelsey Schwensen, Yen Y Wang, Karissa Finke, Anne O'Dea, Lauren Nye, Manana Elia, Gregory Crane, Richard McKittrick, Robert Pluenneke, Sheshadri Madhusudhana, Larry Beck, Roberto Rodriguez, Anuj Shrestha, Larry Corum, Mark Marsico, Andrew K Godwin, Qamar Khan, Priyanka Sharma. Impact of low versus negative estrogen/progesterone receptor status on clinico-pathologic characteristics and survival outcomes in HER2 negative 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 PS6-04.

Randomized Phase II Trial of Anthracycline-free and Anthracycline-containing Neoadjuvant Carboplatin Chemotherapy Regimens in Stage I-III Triple-negative Breast Cancer (NeoSTOP)

PURPOSE

Addition of carboplatin (Cb) to anthracycline chemotherapy improves pathologic complete response (pCR), and carboplatin plus taxane regimens also yield encouraging pCR rates in triple-negative breast cancer (TNBC). Aim of the NeoSTOP multisite randomized phase II trial was to assess efficacy of anthracycline-free and anthracycline-containing neoadjuvant carboplatin regimens.

PATIENTS AND METHODS

Patients aged ≥18 years with stage I-III TNBC were randomized (1:1) to receive either paclitaxel (P) weekly × 12 plus carboplatin AUC6 every 21 days × 4 followed by doxorubicin/cyclophosphamide (AC) every 14 days × 4 (CbP → AC, arm A), or carboplatin AUC6 + docetaxel (D) every 21 days × 6 (CbD, arm B). Stromal tumor-infiltrating lymphocytes (sTIL) were assessed. Primary endpoint was pCR in breast and axilla. Other endpoints included residual cancer burden (RCB), toxicity, cost, and event-free (EFS) and overall survival (OS).

RESULTS

One hundred patients were randomized; arm A (n = 48) or arm B (n = 52). pCR was 54% [95% confidence interval (CI), 40%-69%] in arm A and 54% (95% CI, 40%-68%) in arm B. RCB 0+I rate was 67% in both arms. Median sTIL density was numerically higher in those with pCR compared with those with residual disease (20% vs. 5%; P = 0.25). At median follow-up of 38 months, EFS and OS were similar in the two arms. Grade 3/4 adverse events were more common in arm A compared with arm B, with the most notable differences in neutropenia (60% vs. 8%; P < 0.001) and febrile neutropenia (19% vs. 0%; P < 0.001). There was one treatment-related death (arm A) due to acute leukemia. Mean treatment cost was lower for arm B compared with arm A (P = 0.02).

CONCLUSIONS

The two-drug CbD regimen yielded pCR, RCB 0+I, and survival rates similar to the four-drug regimen of CbP → AC, but with a more favorable toxicity profile and lower treatment-associated cost.

Extinction of chromosomes due to specialization is a universal occurrence

The human X and Y chromosomes evolved from a pair of autosomes approximately 180 million years ago. Despite their shared evolutionary origin, extensive genetic decay has resulted in the human Y chromosome losing 97% of its ancestral genes while gene content and order remain highly conserved on the X chromosome. Five 'stratification' events, most likely inversions, reduced the Y chromosome's ability to recombine with the X chromosome across the majority of its length and subjected its genes to the erosive forces associated with reduced recombination. The remaining functional genes are ubiquitously expressed, functionally coherent, dosage-sensitive genes, or have evolved male-specific functionality. It is unknown, however, whether functional specialization is a degenerative phenomenon unique to sex chromosomes, or if it conveys a potential selective advantage aside from sexual antagonism. We examined the evolution of mammalian orthologs to determine if the selective forces that led to the degeneration of the Y chromosome are unique in the genome. The results of our study suggest these forces are not exclusive to the Y chromosome, and chromosomal degeneration may have occurred throughout our evolutionary history. The reduction of recombination could additionally result in rapid fixation through isolation of specialized functions resulting in a cost-benefit relationship during times of intense selective pressure.

Attributions of responsibility in father-daughter incest in relation to gender, socio-economic status, ethnicity, and experiential differences in participants

One hundred and fifty-seven state college undergraduates (84 females and 73 males) answered the Jackson Incest Blame Scale [JIBS] modified to include mother-blaming after reading one of four vignettes about father-daughter incest in high or low SES White or Black families. Responses about incest prevalence (created for this study) in families with different ethnic and SES backgrounds varied with gender and SES of participants. Gender differences include blame of offender, situation, victim, and mother on the modified JIBS. Parents blamed the offender more than non-parents. Participants who knew an incest survivor disagreed significantly more with victim-blaming statements than those who did not know a survivor of incest.