Incidence and outcome of brain and/or leptomeningeal metastases in HER2-low metastatic breast cancer in the French ESME cohort

BACKGROUND

Breast cancer (BC) is the second most common cancer that metastasizes to the brain. Particularly up to half of patients with human epidermal growth factor receptor 2 (HER2)-positive (HER2+) metastatic breast cancer (mBC) may develop brain metastases over the course of the disease. Nevertheless, little is known about the prevalence and the outcome of brain and leptomeningeal metastases (BLMM) in HER2-low BC. We compared the cumulative incidence of BLMM and associated outcomes among patients with HER2-low, HER2-negative (HER2-) and HER2+ mBC.

PATIENTS AND METHODS

This cohort study was conducted from the Epidemiological Strategy and Medical Economics (ESME) mBC database and included patients treated for mBC between 2012 and 2020 across 18 French comprehensive cancer centers and with known HER2 and hormone receptor (HR) status. The cumulative incidence of BLMM after metastatic diagnosis was estimated using a competing risk methodology with death defined as a competing event.

RESULTS

19 585 patients were included with 6118 (31.2%), 9943 (50.8%) and 3524 (18.0%) being HER2-low, HER2- and HER2+ mBC, respectively. After a median follow-up of 48.6 months [95% confidence interval (CI) 47.7-49.3 months], BLMM were reported in 4727 patients: 1192 (25.2%) were diagnosed with BLMM at first metastatic diagnosis and 3535 (74.8%) after metastatic diagnosis. Multivariable analysis adjusted for age, histological grade, metastases-free interval and HR status showed that the risk of BLMM at metastatic diagnosis was similar in patients with HER2- compared to HER2-low mBC [odds ratio (OR) (95% CI) 1.00 (0.86-1.17)] and higher in those with HER2+ compared to HER2-low [OR (95% CI) 2.23 (1.87-2.66)]. Similar results were found after metastatic diagnosis; the risk of BLMM was similar in HER2- compared to HER2-low [subdistribution hazard ratio (sHR) (95% CI) 1.07 (0.98-1.16)] and higher in the HER2+ group [sHR (95% CI) 1.56 (1.41-1.73)].

CONCLUSIONS

The prevalence and evolution of BLMM in HER2-low mBC are similar to those in patients with HER2- tumors. In contrast to patients with HER2+ mBC, the prognosis of BLMM remains dismal in this population.

Tucatinib Combination Treatment After Trastuzumab-Deruxtecan in Patients With ERBB2-Positive Metastatic Breast Cancer

Importance

Little is known regarding the outcomes associated with tucatinib combined with trastuzumab and capecitabine (TTC) after trastuzumab-deruxtecan exposure among patients with ERBB2 (previously HER2)-positive metastatic breast cancer (MBC).

Objective

To investigate outcomes following TTC treatment in patients with ERBB2-positive MBC who had previously received trastuzumab-deruxtecan.

Design, Setting, and Participants

This cohort study included all patients with MBC who were treated in 12 French comprehensive cancer centers between August 1, 2020, and December 31, 2022.

Exposure

Tucatinib combined with trastuzumab and capecitabine administered at the recommended dose.

Main Outcomes and Measures

Clinical end points included progression-free survival (PFS), time to next treatment (TTNT), overall survival (OS), and overall response rate (ORR).

Results

A total of 101 patients with MBC were included (median age, 56 [range, 31-85] years). The median number of prior treatment lines for metastatic disease at TTC treatment initiation was 4 (range, 2-15), including 82 patients (81.2%) with previous trastuzumab and/or pertuzumab and 94 (93.1%) with previous ado-trastuzumab-emtansine) exposure. The median duration of trastuzumab-deruxtecan treatment was 8.9 (range, 1.4-25.8) months, and 82 patients (81.2%) had disease progression during trastuzumab-deruxtecan treatment, whereas 18 (17.8%) had stopped trastuzumab-deruxtecan for toxic effects and 1 (1.0%) for other reasons. Tucatinib combined with trastuzumab and capecitabine was provided as a third- or fourth-line treatment in 37 patients (36.6%) and was the immediate treatment after trastuzumab-deruxtecan in 86 (85.1%). With a median follow-up of 11.6 (95% CI, 10.5-13.4) months, 76 of 101 patients (75.2%) stopped TTC treatment due to disease progression. The median PFS was 4.7 (95% CI, 3.9-5.6) months; median TTNT, 5.2 (95% CI, 4.5-7.0) months; and median OS, 13.4 (95% CI, 11.1 to not reached [NR]) months. Patients who received TTC immediately after trastuzumab-deruxtecan had a median PFS of 5.0 (95% CI, 4.2-6.0) months; median TTNT of 5.5 (95% CI, 4.8-7.2) months, and median OS of 13.4 (95% CI, 11.9-NR) months. Those who received TTC due to trastuzumab-deruxtecan toxicity-related discontinuation had a median PFS of 7.3 (95% CI, 3.0-NR) months. Best ORR was 29 of 89 patients (32.6%). Sixteen patients with active brain metastasis had a median PFS of 4.7 (95% CI, 3.0-7.3) months, median TTNT of 5.6 (95% CI, 4.4 to NR), and median OS of 12.4 (95% CI, 8.3-NR) months.

Conclusions and Relevance

In this study, TTC therapy was associated with clinically meaningful outcomes in patients with ERBB2-positive MBC after previous trastuzumab-deruxtecan treatment, including those with brain metastases. Prospective data on optimal drug sequencing in this rapidly changing therapeutic landscape are needed.

p4EBP1 staining predicts outcome in ER-positive endocrine-resistant metastatic breast cancer patients treated with everolimus and exemestane

BACKGROUND

To identify patients most likely to respond to everolimus, a mammalian target of rapamycin (mTOR) inhibitor, a prospective biomarker study was conducted in hormone receptor-positive endocrine-resistant metastatic breast cancer patients treated with exemestane-everolimus therapy.

METHODS

Metastatic tumor biopsies were processed for immunohistochemical staining (p4EBP1, PTEN, pAKT, LKB1, and pS6K). ESR1, PIK3CA and AKT1 gene mutations were detected by NGS. The primary endpoint was the association between the p4EBP1 expression and clinical benefit rate (CBR) at 6 months of everolimus plus exemestane treatment.

RESULTS

Of 150 patients included, 107 were evaluable for the primary endpoint. p4EBP1 staining above the median (Allred score ≥6) was associated with a higher CBR at 6 months (62% versus 40% in high-p4EBP1 versus low-p4EBP1, χ2 test, p = 0.026) and a longer progression-free survival (PFS) (median PFS of 9.2 versus 5.8 months in high-p4EBP1 versus low-p4EBP1; p = 0.02). When tested with other biomarkers, only p4EBP1 remained a significant predictive marker of PFS in multivariate analysis (hazard ratio, 0.591; p = 0.01).

CONCLUSIONS

This study identified a subset of patients with hormone receptor-positive endocrine-resistant metastatic breast cancer and poor outcome who would derive less benefit from everolimus and exemestane. p4EBP1 may be a useful predictive biomarker in routine clinical practice.

CLINICAL TRIAL REGISTRATION

NCT02444390.

Efficacy of antiandrogens in androgen receptor-positive triple-negative metastatic breast cancer: Real-life data

Antiandrogens (AA) have been tested in clinical trials in androgen receptor (AR) + triple-negative breast cancer (TNBC). We aim to assess the clinical benefit rate (CBR) of AA in real life. The primary end-point was CBR at 6 months. Twenty-four patients were assessable and received: abiraterone acetate (62 %), enzalutamide (8 %) and bicalutamide (30 %). CBR at 6 months was 29 % (7/24) with 2 CR, 3 PR and 2 SD. Four patients had a clinical benefit >12 months. Real-life efficacy of AA use in metastatic AR + TNBC are in line with data from published trials.

First-line real-world treatment patterns and survival outcomes in women younger or older than 40 years with metastatic breast cancer in the real-life multicenter French ESME cohort

AIM

To describe first-line treatment patterns, overall survival (OS) and real-world progression-free survival (rwPFS) in young women (<40) with metastatic breast cancer (mBC), as compared to women aged 40-69.

MATERIALS AND METHODS

Data on adult women diagnosed with mBC (2008-2017) were extracted from the ESME mBC database (NCT03275311) which includes consecutive patients starting first-line metastatic treatment in one of the 18 French Comprehensive cancer centers. We reported first-line therapeutic strategy and prognostic factors of OS and rwPFS for women aged < 40 and 40-69.

RESULTS

In total, 14,897 mBC women were included (1512 aged <40). HR+ /HER2- mBC was the most frequent subtype. First-line treatment differed between young patients and older ones for HR+ /HER2- and Triple Negative (TN) mBC. Median OS for women aged < 40 and 40-69, respectively, was 46.9 and 46.2 months for HR+ /HER2- mBC; 13.5 and 15.2 for TN mBC; and, 60.7 and 55.1 for HER2 + mBC. Median rwPFS under first line treatment was 11.6 and 11.9 months for HR+ /HER2- in women aged < 40 and 40-69, respectively; 5.5 and 5.9 for TN, and, 13.3 and 12.9 for HER2 + . Factors associated with shorter OS and rwPFS were similar for both women aged < 40 and 40-69 and included ≥ 3 metastatic sites, visceral metastases, and longer MFI, with time-varying effects observed for several prognostic factors.

CONCLUSION

Young women presented more frequently with TN and HER2 + subtypes and aggressive mBC than women aged 40-69 did. Prognostic factors of OS and rwPFS were quite similar between age groups and mBC subtypes.

Neratinib + fulvestrant + trastuzumab for HR-positive, HER2-negative, HER2-mutant metastatic breast cancer: outcomes and biomarker analysis from the SUMMIT trial

BACKGROUND

HER2 mutations are targetable alterations in patients with hormone receptor-positive (HR+) metastatic breast cancer (MBC). In the SUMMIT basket study, patients with HER2-mutant MBC received neratinib monotherapy, neratinib + fulvestrant, or neratinib + fulvestrant + trastuzumab (N + F + T). We report results from 71 patients with HR+, HER2-mutant MBC, including 21 (seven in each arm) from a randomized substudy of fulvestrant versus fulvestrant + trastuzumab (F + T) versus N + F + T.

PATIENTS AND METHODS

Patients with HR+ HER2-negative MBC with activating HER2 mutation(s) and prior cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) therapy received N + F + T (oral neratinib 240 mg/day with loperamide prophylaxis, intramuscular fulvestrant 500 mg on days 1, 15, and 29 of cycle 1 then q4w, intravenous trastuzumab 8 mg/kg then 6 mg/kg q3w) or F + T or fulvestrant alone. Those whose disease progressed on F + T or fulvestrant could cross-over to N + F + T. Efficacy endpoints included investigator-assessed objective response rate (ORR), clinical benefit rate (RECIST v1.1), duration of response, and progression-free survival (PFS). Plasma and/or formalin-fixed paraffin-embedded tissue samples were collected at baseline; plasma was collected during and at end of treatment. Extracted DNA was analyzed by next-generation sequencing.

RESULTS

ORR for 57 N + F + T-treated patients was 39% [95% confidence interval (CI) 26% to 52%); median PFS was 8.3 months (95% CI 6.0-15.1 months). No responses occurred in fulvestrant- or F + T-treated patients; responses in patients crossing over to N + F + T supported the requirement for neratinib in the triplet. Responses were observed in patients with ductal and lobular histology, 1 or ≥1 HER2 mutations, and co-occurring HER3 mutations. Longitudinal circulating tumor DNA sequencing revealed acquisition of additional HER2 alterations, and mutations in genes including PIK3CA, enabling further precision targeting and possible re-response.

CONCLUSIONS

The benefit of N + F + T for HR+ HER2-mutant MBC after progression on CDK4/6is is clinically meaningful and, based on this study, N + F + T has been included in the National Comprehensive Cancer Network treatment guidelines. SUMMIT has improved our understanding of the translational implications of targeting HER2 mutations with neratinib-based therapy.

Real-world clinical and survival outcomes of patients with early relapsed triple-negative breast cancer from the ESME national cohort

BACKGROUND

Early metastatic relapse of triple-negative breast cancer (mTNBC) after anthracyclins and/or taxanes based (A/T) primary treatment represents a highly aggressive cancer situation requiring urgent characterisation and handling. Epidemio-Strategy-Medico-Economical-Metastatic Breast Cancer (ESME-MBC) database, a multicenter, national, observational cohort (NCT03275311) provides recent data on this entity.

METHODS

All ESME patients diagnosed between 2008 and 2020 with mTNBC occurring as a relapse after a systemic neoadjuvant/adjuvant taxane and/or anthracycline-based chemotherapy were included. Early relapses were defined by a metastatic diagnosis up to 12 months of the end of neo/adjuvant A/T chemotherapy. We assessed overall survival (OS) and progression-free-survival under first-line treatment (PFS1) by early versus late relapse (≥12 months).

RESULTS

Patients with early relapse (N = 881, 46%) were younger and had a larger tumour burden at primary diagnosis than those with late relapses (N = 1045). Early relapse rates appeared stable over time. Median OS was 10.1 months (95% CI 9.3-10.9) in patients with early relapse versus 17.1 months (95% CI 15.7-18.2) in those with late relapse (adjusted hazard-ratio (aHR): 1.92 (95% CI 1.73-2.13); p < 0.001). The median PFS1 was respectively 3.1 months (95% CI 2.9-3.4) and 5.3 months (95% CI 5.1-5.8); (aHR: 1.66; [95% CI 1.50-1.83]; p < 0.001). Among early relapsed patients, a higher number of metastatic sites, visceral disease but not treatment types, were independently associated with a poorer OS.

CONCLUSION

These real-world data provide strong evidence on the dismal prognosis, higher treatment resistance and major unmet medical need associated with early relapsed mTNBC. Database registration: clinicaltrials.gov Identifier NCT032753.

Overall survival in the OlympiA phase III trial of adjuvant olaparib in patients with germline pathogenic variants in BRCA1/2 and high risk, early breast cancer

BACKGROUND

The randomized, double-blind OlympiA trial compared 1 year of the oral poly(adenosine diphosphate-ribose) polymerase inhibitor, olaparib, to matching placebo as adjuvant therapy for patients with pathogenic or likely pathogenic variants in germline BRCA1 or BRCA2 (gBRCA1/2pv) and high-risk, human epidermal growth factor receptor 2-negative, early breast cancer (EBC). The first pre-specified interim analysis (IA) previously demonstrated statistically significant improvement in invasive disease-free survival (IDFS) and distant disease-free survival (DDFS). The olaparib group had fewer deaths than the placebo group, but the difference did not reach statistical significance for overall survival (OS). We now report the pre-specified second IA of OS with updates of IDFS, DDFS, and safety.

PATIENTS AND METHODS

One thousand eight hundred and thirty-six patients were randomly assigned to olaparib or placebo following (neo)adjuvant chemotherapy, surgery, and radiation therapy if indicated. Endocrine therapy was given concurrently with study medication for hormone receptor-positive cancers. Statistical significance for OS at this IA required P < 0.015.

RESULTS

With a median follow-up of 3.5 years, the second IA of OS demonstrated significant improvement in the olaparib group relative to the placebo group [hazard ratio 0.68; 98.5% confidence interval (CI) 0.47-0.97; P = 0.009]. Four-year OS was 89.8% in the olaparib group and 86.4% in the placebo group (Δ 3.4%, 95% CI -0.1% to 6.8%). Four-year IDFS for the olaparib group versus placebo group was 82.7% versus 75.4% (Δ 7.3%, 95% CI 3.0% to 11.5%) and 4-year DDFS was 86.5% versus 79.1% (Δ 7.4%, 95% CI 3.6% to 11.3%), respectively. Subset analyses for OS, IDFS, and DDFS demonstrated benefit across major subgroups. No new safety signals were identified including no new cases of acute myeloid leukemia or myelodysplastic syndrome.

CONCLUSION

With 3.5 years of median follow-up, OlympiA demonstrates statistically significant improvement in OS with adjuvant olaparib compared with placebo for gBRCA1/2pv-associated EBC and maintained improvements in the previously reported, statistically significant endpoints of IDFS and DDFS with no new safety signals.

Genomics to select treatment for patients with metastatic breast cancer

Cancer progression is driven in part by genomic alterations¹. The genomic characterization of cancers has shown interpatient heterogeneity regarding driver alterations², leading to the concept that generation of genomic profiling in patients with cancer could allow the selection of effective therapies^3,4. Although DNA sequencing has been implemented in practice, it remains unclear how to use its results. A total of 1,462 patients with HER2-non-overexpressing metastatic breast cancer were enroled to receive genomic profiling in the SAFIR02-BREAST trial. Two hundred and thirty-eight of these patients were randomized in two trials (nos. NCT02299999 and NCT03386162) comparing the efficacy of maintenance treatment⁵ with a targeted therapy matched to genomic alteration. Targeted therapies matched to genomics improves progression-free survival when genomic alterations are classified as level I/II according to the ESMO Scale for Clinical Actionability of Molecular Targets (ESCAT)⁶ (adjusted hazards ratio (HR): 0.41, 90% confidence interval (CI): 0.27-0.61, P < 0.001), but not when alterations are unselected using ESCAT (adjusted HR: 0.77, 95% CI: 0.56-1.06, P = 0.109). No improvement in progression-free survival was observed in the targeted therapies arm (unadjusted HR: 1.15, 95% CI: 0.76-1.75) for patients presenting with ESCAT alteration beyond level I/II. Patients with germline BRCA1/2 mutations (n = 49) derived high benefit from olaparib (gBRCA1: HR = 0.36, 90% CI: 0.14-0.89; gBRCA2: HR = 0.37, 90% CI: 0.17-0.78). This trial provides evidence that the treatment decision led by genomics should be driven by a framework of target actionability in patients with metastatic breast cancer.

High p16 expression and heterozygous RB1 loss are biomarkers for CDK4/6 inhibitor resistance in ER+ breast cancer

CDK4/6 inhibitors combined with endocrine therapy have demonstrated higher antitumor activity than endocrine therapy alone for the treatment of advanced estrogen receptor-positive breast cancer. Some of these tumors are de novo resistant to CDK4/6 inhibitors and others develop acquired resistance. Here, we show that p16 overexpression is associated with reduced antitumor activity of CDK4/6 inhibitors in patient-derived xenografts (n = 37) and estrogen receptor-positive breast cancer cell lines, as well as reduced response of early and advanced breast cancer patients to CDK4/6 inhibitors (n = 89). We also identified heterozygous RB1 loss as biomarker of acquired resistance and poor clinical outcome. Combination of the CDK4/6 inhibitor ribociclib with the PI3K inhibitor alpelisib showed antitumor activity in estrogen receptor-positive non-basal-like breast cancer patient-derived xenografts, independently of PIK3CA, ESR1 or RB1 mutation, also in drug de-escalation experiments or omitting endocrine therapy. Our results offer insights into predicting primary/acquired resistance to CDK4/6 inhibitors and post-progression therapeutic strategies.

An immunological signature to predict outcome in patients with triple-negative breast cancer with residual disease after neoadjuvant chemotherapy

Background

When triple-negative breast cancer (TNBC) patients have residual disease after neoadjuvant chemotherapy (NACT), they have a high risk of metastatic relapse. With immune infiltrate in TNBC being prognostic and predictive of response to treatment, our aim was to develop an immunologic transcriptomic signature using post-NACT samples to predict relapse.

Materials and methods

We identified 115 samples of residual tumors from post-NACT TNBC patients. We profiled the expression of 770 genes related to cancer microenvironment using the NanoString PanCancer IO360 panel to develop a prognostic transcriptomic signature, and we describe the immune microenvironments of the residual tumors.

Results

Thirty-eight (33%) patients experienced metastatic relapse. Hierarchical clustering separated patients into five clusters with distinct prognosis based on pathways linked to immune activation, epithelial-to-mesenchymal transition and cell cycle. The immune microenvironment of the residual disease was significantly different between patients who experienced relapse compared to those who did not, the latter having significantly more effector antitumoral immune cells, with significant differences in lymphoid subpopulations. We selected eight genes linked to immunity (BLK, GZMM, CXCR6, LILRA1, SPIB, CCL4, CXCR4, SLAMF7) to develop a transcriptomic signature which could predict relapse in our cohort. This signature was validated in two external cohorts (KMplot and METABRIC).

Conclusions

Lack of immune activation after NACT is associated with a high risk of distant relapse. We propose a prognostic signature based on immune infiltrate that could lead to targeted therapeutic strategies to improve patient prognosis.

•

Infiltrate of cytotoxic cells is higher in the residual disease of TNBC patients who will not experience metastatic relapse.

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Underexpression of immune-related pathways is associated with metastatic relapse in residual disease of TNBC patients.

•

An immune gene-based signature can predict metastatic relapse in TNBC patients after NACT.

Natural History and Characteristics of ERBB2-mutated Hormone Receptor-positive Metastatic Breast Cancer: A Multi-institutional Retrospective Case-control Study from AACR Project GENIE

PURPOSE

We wanted to determine the prognosis and the phenotypic characteristics of hormone receptor-positive advanced breast cancer tumors harboring an ERBB2 mutation in the absence of a HER2 amplification.

EXPERIMENTAL DESIGN

We retrospectively collected information from the American Association of Cancer Research-Genomics Evidence Neoplasia Information Exchange registry database from patients with hormone receptor-positive, HER2-negative, ERBB2-mutated advanced breast cancer. Phenotypic and co-mutational features, as well as response to treatment and outcome were compared with matched control cases ERBB2 wild type.

RESULTS

A total of 45 ERBB2-mutant cases were identified for 90 matched controls. The presence of an ERBB2 mutation was not associated with worse outcome determined by overall survival (OS) from first metastatic relapse. No significant differences were observed in phenotypic characteristics apart from higher lobular infiltrating subtype in the ERBB2-mutated group. ERBB2 mutation did not seem to have an impact in response to treatment or time-to-progression (TTP) to endocrine therapy compared with ERBB2 wild type. In the co-mutational analyses, CDH1 mutation was more frequent in the ERBB2-mutated group (FDR < 1). Although not significant, fewer co-occurring ESR1 mutations and more KRAS mutations were identified in the ERBB2-mutated group.

CONCLUSIONS

ERBB2-activating mutation was not associated with a worse OS from time of first metastatic relapse, or differences in TTP on treatment as compared with a series of matched controls. Although not significant, differences in coexisting mutations (CDH1, ESR1, and KRAS) were noted between the ERBB2-mutated and the control group.

Abstract GS1-10: Clinical utility of molecular tumor profiling: Results from the randomized trial SAFIR02-BREAST

Background: While studies have shown feasibility and reported preliminary evidence of utility, there is no evidence that multigene sequencing improves outcome in patients with metastatic cancer. The aim of the present study was to assess the clinical utility of multigene sequencing and DNA copy number analyses.. Methods: In SAFIR02-BREAST (NCT: 02299999) and SAFIR-PI3K (NCT: 03386162), open-label multicentric phase II randomized trials, patients were selected if they had a Her2-negative metastatic breast cancer eligible to 1st or 2nd line chemotherapy. Patients underwent a pre-treatment biopsy of metastatic disease when feasible, followed by genomic analysis by next generation sequencing and SNParray. After 6 to 8 cycles of induction chemotherapy, patients without progressive disease and presenting an actionable genomic alteration, were randomized between targeted therapies matched to genomic alterations or maintenance chemotherapy. The primary objective was to evaluate whether targeted therapies guided by genomics improves progression-free survival (PFS) as compared to maintenance chemotherapy, in a pooled analyses of SAFIR02-BREAST and SAFIR-PI3K populations. A hierarchical testing was applied. The efficacy of targeted therapies matched to genomic alterations was first tested in patients presenting an ESCAT I/II alteration (ESMO Scale of Actionability of Molecular Targets). If a p value &lt;0.1 was observed in the first step, analyses were then performed in the Intent-to-treat population. Results: Out of the 1462 patients included, 238 (16%) were subsequently randomized between maintenance chemotherapy (n=81) and targeted therapy (n=157). In 115 patients presenting an ESCAT I/II genomic alteration, the median PFS was 9.1 months (90%CI: 7.1-9.8) and 2.8 (90%CI: 2.1-4.8) in matched targeted therapy and maintenance chemotherapy arms respectively (adjusted HR for stratification factors =0.41;90%CI: 0.27-0.61, p&lt;0.001). In the overall population, there was no significant difference in the duration of PFS between the two arms (adjusted HR: 0.77 (95%CI: 0.56- 1.06, p=0.109). ESCAT classification was highly predictive for the benefit of targeted therapies matched to genomic alterations (interaction test, p= 0.004). Targeted therapies matched to genomic alterations were not effective in patients without ESCAT I/II alteration (HR: 1.15, 95%CI: 0.76-1.75). The SNP array analyses (n=926) identified 21 genes altered more frequently in metastases as compared to primary tumors (TCGA+ METABRIC). Of these, focal TERT amplifications were associated with a poor outcome. Focal CDK4 amplifications were observed after resistance to CDK4 inhibitors. Finally, high HRD was associated with longer PFS in patients with BRCA mutation treated with olaparib (HR: 0.32 [95%CI: 0.12;0.83], p=0.013).. Conclusion: SAFIR02/PI3K trials report that the clinical use of multigene sequencing must be driven by a framework of actionability, and identifies new genomic alterations associated with metastatic evolution and drug resistance or sensitivity.

Citation Format: Fabrice André, Anthony Gonçalves, Thomas Filleron, Florence Dalenc, Amélie Lusque, Mario Campone, Marie-Paule Sablin, Hervé Bonnefoi, Ivan Bieche, Ludovic Lacroix, Alicia Tran-Dien, Marta Jimenez, Alexandra Jacquet, Qing Wang, Etienne Rouleau, David Gentien, Isabelle Soubeyran, Alain Morel, Monica Arnedos, Thomas Bachelot. Clinical utility of molecular tumor profiling: Results from the randomized trial SAFIR02-BREAST [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 GS1-10.

A phase II randomised study of preoperative trastuzumab alone or combined with everolimus in patients with early HER2-positive breast cancer and predictive biomarkers (RADHER trial)

INTRODUCTION

Resistance to trastuzumab in breast cancer is an ongoing challenge. Clinical and biological effects of co-targeting HER2 and mammalian target of rapamycin (mTOR) in patients with HER2-positive early operable breast cancer via the addition of everolimus to preoperative trastuzumab were evaluated in a phase II randomised study.

METHODS

Patients were randomised 1:1 to receive trastuzumab (4 mg/kg initial dose then 2 mg/kg weekly for 5 weeks) alone or combined with everolimus (10 mg/day for 6 weeks) and then underwent surgery. Tumours were assessed by clinical examination and echography at the baseline and on treatment. The primary end-point was the clinical response rate at 6 weeks. Pathological response and safety were also evaluated. Baseline and surgery tumour samples were assessed by immunohistochemistry and multiplex immunoanalysis for predictive downstream effectors of the PI3K/AKT/mTOR and MAP kinase (MAPK) pathways.

RESULTS

Eighty-two patients were enrolled, 41 per arm. The clinical response rates were 34.1% and 43.9% with trastuzumab alone and combined with everolimus, respectively. Pathological response rates were 43.6% and 47.5%, respectively. Addition of everolimus increased toxicity, notably mucositis (82.5% versus 5.0%) and rash (57.5% versus 10.0%), but grade III/IV events were rare. No correlation between response to treatments and baseline candidate biomarkers was identified, except for PIK3CA mutations which were found to predict trastuzumab resistance. Significant changes were seen in several MAPK pathway effectors after combination therapy.

CONCLUSIONS

The addition of everolimus did not improve the efficacy, but induced MAPK signalling. Combination therapy to overcome pathway cross-talk should be considered to maximise the effectiveness of trastuzumab in this setting. ClinicalTrial.gov Identifier NCT00674414.

Optimizing the Management of Cancer Patients Treated With Systemic Therapies During the COVID-19 Pandemic: The New Role of PCR and CT Scan

In late 2019 and early 2020, the world witnessed the outbreak of the SARS-CoV-2 (also referred as COVID-19) in Wuhan, China. Its rapid expansion worldwide and its contagiousness rate have forced the activation of several measures to contain the pandemic, mostly through confinement and identification of infected patients and potential contacts by testing.

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.

QualFatigue study: which factors influence the use of specific interventions for breast cancer survivors with fatigue? A cross-sectional exploratory study

PURPOSE

International guidelines recommend specific interventions to reduce cancer-related fatigue (CRF). Evidence suggests underutilization of these interventions among breast cancer survivors. The QualFatigue study aimed to explore the potential factors influencing the use of specific interventions, for relief, in patients with CRF through qualitative analyses.

METHODS

Patients with stage I-III breast cancer, and CRF ≥4 on a 10-point numerical scale were recruited within 6-24 months at the end of their primary treatment. Semi-structured interviews were performed. Emergent themes were identified using a stepped content analysis (QDA Miner software).

RESULTS

Data saturation was achieved with 15 interviews. Four main themes emerged as potential sources of influence in the participants' use of specific interventions: (1) expectations regarding the management of CRF, (2) representations of the benefits provided by the interventions, (3) individual physical and psychological conditions, and (4) social and environmental situations. Six key levers came out transversally to optimize the use of specific interventions to relieve CRF: (1) listening and recognition of the individual difficulties and needs; (2) individual and global health assessments; (3) information and advice on how to manage CRF; (4) discussion groups focused on the management of CRF; (5) group activities; and (6) professional and personalized guidance.

CONCLUSION

This study calls for multi-level action to address many persistent barriers and exploit levers in the management of CRF.

Ketogenic diet and ketone bodies enhance the anticancer effects of PD-1 blockade

Limited experimental evidence bridges nutrition and cancer immunosurveillance. Here, we show that ketogenic diet (KD) — or its principal ketone body, 3-hydroxybutyrate (3HB), most specifically in intermittent scheduling — induced T cell–dependent tumor growth retardation of aggressive tumor models. In conditions in which anti–PD-1 alone or in combination with anti–CTLA-4 failed to reduce tumor growth in mice receiving a standard diet, KD, or oral supplementation of 3HB reestablished therapeutic responses. Supplementation of KD with sucrose (which breaks ketogenesis, abolishing 3HB production) or with a pharmacological antagonist of the 3HB receptor GPR109A abolished the antitumor effects. Mechanistically, 3HB prevented the immune checkpoint blockade–linked upregulation of PD-L1 on myeloid cells, while favoring the expansion of CXCR3⁺ T cells. KD induced compositional changes of the gut microbiota, with distinct species such as Eisenbergiella massiliensis commonly emerging in mice and humans subjected to carbohydrate-low diet interventions and highly correlating with serum concentrations of 3HB. Altogether, these results demonstrate that KD induces a 3HB-mediated antineoplastic effect that relies on T cell–mediated cancer immunosurveillance.

Real-life prognosis of 5041 bone-only metastatic breast cancer patients in the multicenter national observational ESME program

BACKGROUND

Bone-only (BO) metastatic breast cancer (MBC) is considered a more favorable entity than other MBC presentations. However, only few retrospective series and data from selected randomized controlled trials have been reported so far.

METHODS

Using the French national multicenter ESME (Epidemiological Strategy and Medico Economics) Data Platform, the primary objective of our study was to compare the overall survival (OS) of patients with BO versus non-BO MBC at diagnosis, with adjustment on main prognostic factors using a propensity score. Secondary objectives were to compare first-line progression-free survival (PFS1), describe treatment patterns, and estimate factors associated with OS.

RESULTS

Out of 20,095 eligible women, 5041 (22.4%) patients had BO disease [hormone-receptor positive (HR+)/human epidermal growth-factor-receptor-2 negative (HER2-), n = 4 102/13,229 (31%); HER2+, n = 644/3909 (16.5%); HR-/HER2-, n = 295/2 957 (10%)]. BO MBC patients had a better adjusted OS compared with non-BO MBC [52.1 months (95% confidence interval (CI) 50.3-54.1) versus 34.7 months (95% CI 34.0-35.6) respectively]. The 5-year OS rate of BO MBC patients was 43.4% (95% CI 41.7-45.2). They also had a better PFS1 [13.1 months (95% CI 12.6-13.8) versus 8.5 months (95% CI 8.3-8.7), respectively]. This observation could be repeated in all subtypes. BO disease was an independent prognostic factor of OS [hazard ratio 0.68 (95% CI 0.65-0.72), p < 0.0001]. Results were concordant in all analyses.

CONCLUSION

BO MBC patients have better outcomes compared with non-BO MBC, consistently, through all MBC subtypes.

Targeting HER2 (ERBB2) mutation-positive advanced biliary tract cancers with neratinib: Results from the phase II SUMMIT ‘basket’ trial

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Background: Genomic profiling studies have reported somatic HER2 mutations in ~2–5% of biliary tract cancers (BTC). Clinical data from the SUMMIT study demonstrate that neratinib, a pan-HER irreversible tyrosine kinase inhibitor, has encouraging clinical activity in multiple types of HER2-mutant solid tumor malignancies. Methods: SUMMIT is a multi-histology, open-label, phase II ‘basket’ study of neratinib in patients with somatic HER2 mutations (ClinicalTrials.gov NCT01953926). Patients with activating somatic HER2 mutations with different histologies, including BTC, received neratinib monotherapy (240 mg oral daily). Loperamide prophylaxis was mandatory during cycle 1. Efficacy endpoints: objective response rate (ORR, RECIST v1.1); clinical benefit rate (CBR); duration of response; progression-free survival (PFS). Adverse events (AEs) were assessed by CTCAE v4.0. Genomic profiling from fresh/archival tumor tissues and/or plasma cfDNA was performed retrospectively by next-generation sequencing (MSK-IMPACT). Results: As of 3-Sep-2020, 25 patients with HER2-mutant BTC were enrolled: gallbladder (40%); intrahepatic (24%); extrahepatic (20%); ampulla of Vater (16%). 68% of patients received ≥2 systemic regimens (96% received prior gemcitabine-based regimens). The S310F/Y variant accounted for nearly half of HER2 mutations (n=11). Other HER2 mutations: V777L (n=5); L755S (n=2); V842I (n=2); R678Q (n=2). Confirmed ORR in 25 evaluable patients was 12% (95% CI 3–31%) and CBR was 20% (95% CI 7–41%), including 3 confirmed PRs and 2 patients with SD for ≥16 weeks. Tumor shrinkage was observed in multiple HER2-activating mutations and enriched in gallbladder and extrahepatic subtypes of BTC. Median PFS was 2.8 (95% CI 1.1–3.7) months; median overall survival (OS) was 5.4 (95% CI 3.7–11.7) months. Nine (36%) patients (3 of whom with ECOG PS 2) came off study within 28 (range 6–47) days of treatment due to clinical deterioration (unrelated to study drug) followed by death. The most common treatment-related AEs (any grade) were diarrhea (56%) and vomiting (48%). Diarrhea was the most common Grade 3 event (24%); 4 patients (16%) required a neratinib dose reduction; no patients discontinued treatment due to diarrhea. Conclusions: Neratinib is safe and tolerable in patients with advanced BTC patients and somatic HER2 mutations. The antitumor activity of neratinib appears comparable to current standards of care, with similar PFS and OS in heavily pretreated patients. Analysis of co-occurring oncogenic mutations and response is ongoing, and consideration is being given to neratinib-based combination regimens to further improve outcomes in this setting. Clinical trial information: NCT01953926.

Analysis of the StoRM cohort reveals physical activity to be associated with survival in metastatic breast cancer

Benefits of physical activity are widely demonstrated for early stage cancers but few studies have focused on metastatic disease. The purpose of this study was to determine the impact of physical activity on survival in patients with metastatic breast cancer. We conducted a secondary analysis of the national, multicentric, non-randomized, prospective cohort SNPs to Risk of Metastasis (StoRM) study. The level of physical activity was self-reported at inclusion and divided into three categories of physical activity: light level, moderate level, and vigorous level. Overall, 833 patients (56.2%) completed the physical activity questionnaire at baseline on average physical activity during the previous year: 11.6% had a light level of physical activity, 69.0% achieved moderate levels of physical activity and 19.3% reported vigorous levels of physical activity. After adjustment for confounding, physical activity was not statistically significantly associated with overall survival in the whole population. Subgroup analysis identified that both vigorous and moderate physical activity were associated with statistically significantly improved overall survival compared to light physical activity level only in the HER2 positive subgroup (HR 0.23; 95% CI 0.07-0.70, p = 0.01 and HR 0.38; 95% CI 0.15-0.96, p = 0.04). Physical activity done during the previous year was associated with survival in HER2 positive metastatic breast cancer patients. These results suggest that overall survival in metastatic breast cancer patients could be improved through physical activity which should be considered as a complementary intervention for these individuals. The study showed that moderate/vigorous levels of physical activity were associated with better overall survival, and that these associations remained statistically significant in multivariate analysis in the HER2 positive subgroup. These results have clinical relevance and justify the recommendations for physical activity interventions in metastatic breast cancer.

Clinical outcome of patients experiencing central nervous system progression on first-line pertuzumab and trastuzumab for HER2-positive metastatic breast cancer in a real-life cohort

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Background: Isolated central nervous system (CNS) progression on first-line systemic therapy with Trastuzumab (T) and Pertuzumab (P) for HER2-positive metastatic breast cancer (MBC) is a therapeutic challenge. Our aim was to describe the clinical outcome and current treatment strategies for such patients in a large retrospective cohort. Methods: Patients (pts) were selected among all MBC pts included in the French Epidemiological Strategy and Medical Economics (ESME) database involving 18 specialized cancer centers (NCT03275311). CNS progression-free survival (CNS-PFS), progression-free survival (PFS) and overall survival (OS) from diagnostic of brain metastases (BM) were estimated using the Kaplan-Meier method. Results: Between January 2008 and December 2016, 995 pts were treated with first-line T and P for their HER2-positive MBC. They were 55 years old in median, with tumors expressing hormone-receptors in 62%. A total of 132 pts (13%) experienced isolated CNS progression on T and P, with a median time from metastatic diagnosis to CNS progression of 12 months. It was the first CNS progression for 108 pts (82%) while 24 (18%) already had BM at time of metastatic relapse. After CNS progression, T and P were continued for 58% of pts (n = 73). The remaining 47 pts were switched to another HER2-directed therapy (T-DM1 for 57%, T alone or combined with chemotherapy for 36% and lapatinib for 21%). Among those 132 pts, 37% received whole-brain radiotherapy, 18% stereotactic radiation therapy, and 11% surgery. Systemic treatment was combined with CNS-directed therapy for 50% of pts. Median follow-up is 21 months (95%CI: 14.9-25.5) from the diagnosis of CNS metastases. Median OS (mOS) of the 132 pts is 35 months (95%CI: 29.2-53,6), and median PFS 7 months (95%CI: 6.3- 9.2). A total of 77 pts (58.3%) experienced a new CNS progression with a median CNS-PFS of 9 months (95%CI: 7.6-12,0). Patient who stayed on T and P had a significantly better OS in comparison to pts who were switched to another systemic HER2-directed therapy (mOS not evaluable vs23 months), whereas PFS and CNS-PFS were similar between groups. Conclusions: In this real life setting, isolated CNS progression occurred among 13% of pts with HER2+ MBC on first-line treatment with T and P, after a median time of 12 months. Following current ASCO recommendations, continuation of T and P after CNS-directed therapy, seemed to be adequate. Nevertheless, time to subsequent progression is short and better therapeutic options are needed.

Characteristics and Outcome of AKT1 E17K-Mutant Breast Cancer Defined through AACR Project GENIE, a Clinicogenomic Registry

AKT inhibitors have promising activity in AKT1 ^E17K-mutant estrogen receptor (ER)-positive metastatic breast cancer, but the natural history of this rare genomic subtype remains unknown. Utilizing AACR Project GENIE, an international clinicogenomic data-sharing consortium, we conducted a comparative analysis of clinical outcomes of patients with matched AKT1 ^E17K-mutant (n = 153) and AKT1-wild-type (n = 302) metastatic breast cancer. AKT1-mutant cases had similar adjusted overall survival (OS) compared with AKT1-wild-type controls (median OS, 24.1 vs. 29.9, respectively; P = 0.98). AKT1-mutant cases enjoyed longer durations on mTOR inhibitor therapy, an observation previously unrecognized in pivotal clinical trials due to the rarity of this alteration. Other baseline clinicopathologic features, as well as durations on other classes of therapy, were broadly similar. In summary, we demonstrate the feasibility of using a novel and publicly accessible clincogenomic registry to define outcomes in a rare genomically defined cancer subtype, an approach with broad applicability to precision oncology. SIGNIFICANCE: We delineate the natural history of a rare genomically distinct cancer, AKT1 ^E17K-mutant ER-positive breast cancer, using a publicly accessible registry of real-world patient data, thereby illustrating the potential to inform drug registration through synthetic control data.See related commentary by Castellanos and Baxi, p. 490.

Modulation of Rb phosphorylation and antiproliferative response to palbociclib: the preoperative-palbociclib (POP) randomized clinical trial

Background

The cyclin-dependent kinase 4 (CDK4)/6 inhibitor Palbociclib is a new standard treatment in hormone-receptor positive breast cancer patients. No predictive biomarkers have been identified and no pharmacodynamics has properly been described so far.

Patients and methods

Patients with early-breast cancer were randomized 3 : 1 to oral palbociclib 125 mg daily for 14 days until the day before the surgery versus no treatment. Primary objective was antiproliferative response defined as a natural logarithm of Ki67 expression at day 15 below 1. Secondary end points were subgroups analyses and safety. Exploratory analyses included search for predictive biomarkers. Immunostainings (Ki67, RB, pRB, p16, pAKT, pER, pCDK2, CyclinD1), FISH (CCND1) and gene expression (GE) arrays were carried out at baseline and at surgery. In addition, activating PIK3CA and AKT1 mutations were assessed at baseline.

Results

74 patients were allocated to palbociclib and 26 to control. Most patients (93%) were hormone-receptor (HR)-positive, whereas 8% were HER2-positive. Palbociclib led to significantly more antiproliferative responses when compared with control (58% versus 12%, P < 0.001), and to a significantly higher Ki67 decrease (P < 0.001). In the HR-positive/HER2-negative subgroup, this antiproliferative effect was even more marked in the palbociclib arm when compared with control (70% versus 9%, P < 0.001). Palbociclib treatment led also to a significantly higher decrease from baseline in phospho-Rb when compared with control (P < 0.001). Among treated patients, changes in Ki67 correlated with changes in phospho-Rb (Spearman rank r = 0.41, P < 0.0001). GE analyses confirmed a major effect on proliferation and cell cycle genes. Among treated patients, CCNE2 expression was significantly more decreased in antiproliferative responders versus nonresponders (P = 0.006).

Conclusion

Short-term preoperative palbociclib decreases Ki67 in early-breast cancer patients. Early decrease of Rb phosphorylation correlates with drug's effect on cell proliferation and could potentially identify patients with primary resistance.

Clinical trial registration

NCT02008734.

Efficacy and Determinants of Response to HER Kinase Inhibition in HER2-Mutant Metastatic Breast Cancer

HER2 mutations define a subset of metastatic breast cancers with a unique mechanism of oncogenic addiction to HER2 signaling. We explored activity of the irreversible pan-HER kinase inhibitor neratinib, alone or with fulvestrant, in 81 patients with HER2-mutant metastatic breast cancer. Overall response rate was similar with or without estrogen receptor (ER) blockade. By comparison, progression-free survival and duration of response appeared longer in ER⁺ patients receiving combination therapy, although the study was not designed for direct comparison. Preexistent concurrent activating HER2 or HER3 alterations were associated with poor treatment outcome. Similarly, acquisition of multiple HER2-activating events, as well as gatekeeper alterations, were observed at disease progression in a high proportion of patients deriving clinical benefit from neratinib. Collectively, these data define HER2 mutations as a therapeutic target in breast cancer and suggest that coexistence of additional HER signaling alterations may promote both de novo and acquired resistance to neratinib. SIGNIFICANCE: HER2 mutations define a targetable breast cancer subset, although sensitivity to irreversible HER kinase inhibition appears to be modified by the presence of concurrent activating genomic events in the pathway. These findings have implications for potential future combinatorial approaches and broader therapeutic development for this genomically defined subset of breast cancer.This article is highlighted in the In This Issue feature, p. 161.

Efficacy of PI3K inhibitors in advanced breast cancer

The phosphoinositide 3 (PI3)-kinase/Akt signaling pathway has always been a focus of interest in breast cancer due to its role in cell growth, cell proliferation, cell migration and deregulated apoptosis. Its activation has been linked to endocrine resistance and worse prognosis in certain subgroups of breast cancer. In addition, deregulation of the PI3K/Akt pathway including PIK3CA activating mutation is frequently present in breast cancer. Multiple efforts have been carried out to target this pathway, initially with pan-PI3K inhibitors with some hint of activity but hampered by their limiting side-effects. A recent large randomized trial in patients with endocrine-resistant PIK3CA-mutant hormone receptor (HR)-positive tumors led to the approval of the first PI3K inhibitor, alpelisib, in combination with fulvestrant. The specificity of alpelisib against the p110α catalytic isoform provided additional efficacy and a better toxicity profile. In this review, we summarize the main research with PI3K inhibitors in breast cancer and we provide some insight of potential future combinations of this treatment in breast cancer patients.

T-cell bispecific antibodies in node-positive breast cancer: novel therapeutic avenue for MHC class I loss variants

BACKGROUND

Tumor-infiltrating lymphocytes (TILs) represent a prognostic factor for survival in primary breast cancer (BC). Nonetheless, neoepitope load and TILs cytolytic activity are modest in BC, compromising the efficacy of immune-activating antibodies, which do not yet compete against immunogenic chemotherapy.

PATIENTS AND METHODS

We analyzed by functional flow cytometry the immune dynamics of primary and metastatic axillary nodes [metastatic lymph nodes (mLN)] in early BC (EBC) after exposure to T-cell bispecific antibodies (TCB) bridging CD3ε and human epidermal growth factor receptor 2 (HER2) or Carcinoembryonic Antigen-Related Cell Adhesion Molecule 5 (CEACAM5), before and after chemotherapy. Human leukocyte antigen (HLA) class I loss was assessed by whole exome sequencing and immunohistochemistry. One hundred primary BC, 64 surrounding 'healthy tissue' and 24 mLN-related parameters were analyzed.

RESULTS

HLA loss of heterozygosity was observed in EBC, at a clonal and subclonal level and was associated with regulatory T cells and T-cell immunoglobulin and mucin-domain-3 expression restraining the immuno-stimulatory effects of neoadjuvant chemotherapy. TCB bridging CD3ε and HER2 or CEACAM5 could bypass major histocompatibility complex (MHC) class I loss, partially rescuing T-cell functions in mLN.

CONCLUSION

TCB should be developed in BC to circumvent low MHC/peptide complexes.

mTORC1 activation assessed in metastatic sample to predict outcome in patients with metastatic breast cancer treated with everolimus-exemestan: Results from the SAFIRTOR study

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Background: Using samples from TAMRAD study (Treilleux, Ann Oncol, 2015), we previously reported that p4EBP1, a downstream protein of mTOR, was associated with higher benefit to everolimus (eve). SAFIRTOR study was designed to validate clinical utility of this biomarker. Methods: Patients (pts) with ER+, HER2 negative, AI resistant MBC were prospectively included (NCT02444390). All pts had a biopsy of a metastatic site and were then treated with standard eve + exemestane (exe) combination. The primary end point was to validate that p4EBP1 expression is associated with longer PFS in patients treated with eve. 120 evaluable pts were needed for the pre planed statistical analysis. All samples were collected and processed in a standardized procedure in order to allow phophoproteins IHC staining. In addition to p4EBP1, we explored prognostic value of pS6K, pAkt, PTEN and LKB1, together with genomic alterations assessed by NGS and CGH arrays. Results: 150 pts were included, 30 pts had no adequate sample, and further 13 had missing clinical data, 107 were evaluable for primary objective. Median age was 62, they had previously progressed on AI treatment, either in the adjuvant (22 pts) or the metastatic setting (83 pts). 20 were considered as primary hormone resistant, 87 as secondary resistant. The median Allread score for p4EBP1 was 5.5 (range: 0-6.5). Analysis of the primary endpoint showed that p4EBP1 staining above the median is associated with a longer PFS on eve+exe. (median PFS: 9.3 months, 95CI 6.3-13.1 for high p4EBP1 versus 5.8 months, 95CI 3.7-7.8 for low p4EBP1, p = 0.02). Prognostic value of high pEBP1 remained significant when assessed in a multivariate analysis along classical clinico-biological prognostic factors for MBC (HR 0.57, 95%CI 0.38-0.88, p = 0.01). In this AI resistant population, the tumor of 42 (46%), 33 (35%) and 5 (5.3%) pts carried an activating mutation for ESR1, PIK3CA and AKT1, respectively. None of these mutational statuses were correlated to outcome. Conclusions: This prospective study validates p4EBP1 expression analysis to select patients most likely to benefit from everolimus + exemestane. Clinical trial information: NCT02444390.

RUBY: A phase II study testing rucaparib in germline (g) BRCA wild-type patients presenting metastatic breast cancer (mBC) with homologous recombination deficiency (HRD)

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Background: PARP-inhibitors improve PFS in mBC patients (pts) harboring a gBRCA mutation (mut). However, unlike ovarian cancer, there is no evidence until now that this class of agents has efficacy in gBRCA wild-type (WT) pts. In RUBY, we evaluated rucaparib in gBRCA WT mBC pts, and whose tumor present with HRD as assessed by genome-wide Loss of Heterozygosity (LOH) score. Methods: 713 gBRCA WT women with HER2- mBC, initiating a first metastatic chemo, were screened for high (≥18%) genomic tumor LOH generated from a SNP array on metastatic sample. Eligible pts with a high LOH score or somatic (s) BRCA mut and ≥1 prior chemo regimen were proposed to enter RUBY and receive oral rucaparib 600 mg BID continuously in 28-day cycles until disease progression. The primary endpoint was clinical benefit rate (CBR), defined by complete (CR) and partial response (PR) or stable disease (SD) ≥16 weeks. We used a Simon’s two-stage design (p0=20%; p1=40%), responses in ≥4/17 pts were expected to move to second step, and ≥11/37 pts to be considered of clinical interest (α=10% and power of 90%). Whole genome sequencing (WGS) was performed retrospectively to further assess potential biomarkers of PARP inhibitor response. Results: Tumors from 221 (31%) pts were LOH high. 41 pts were enrolled, including 4 pts with sBRCA mut. Median prior metastatic chemo lines was 2 (1-5), 17 pts had TNBC at diagnosis. As of 14 Jan 2019, 16 pts were alive, 5 are still on treatment. The median number of cycles was 2 (1 -20), and 37/40 patients were evaluable for CBR. 5 pts (13.5%) demonstrated clinical benefit (1 CR [LOH high], 3 PR [2 LOH high, 1 sBRCA2] and 1 SD>31 weeks [sBRCA1]). 19 pts had grade 3-4 toxicities. 3 pts discontinued due to toxicity. 4/5 responders pts had their tumor profiled by WGS: preliminary analyses showed that 4 pts presented high large scale state transitions, and 3 presented a somatic biallelic loss of function in HR-related genes. The fifth responder harbored a mut on gPALB2 and sBRCA2 at inclusion. Conclusions: In this study, rucaparib demonstrates antitumor activity in a subset of gBRCA WT mBC pts whose tumor has high LOH. Final analyses of WGS will provide insights about HRD signatures and drivers alterations associated with response. Clinical trial information: NCT02505048.

Cyclin E1 Expression and Palbociclib Efficacy in Previously Treated Hormone Receptor-Positive Metastatic Breast Cancer

PURPOSE

A large-panel gene expression analysis was conducted to identify biomarkers associated with the effectiveness of adding palbociclib to fulvestrant.

METHODS

The PALOMA-3 (ClinicalTrials.gov identifier: NCT01942135) trial randomly assigned 521 endocrine-pretreated patients with metastatic breast cancer to receive palbociclib plus fulvestrant or placebo plus fulvestrant. Primary analysis was first conducted on 10 genes on the basis of pathway biology and evidence from previous studies followed by a systematic panel-wide search among 2,534 cancer-related genes. The association of gene expression with the effect of palbociclib on progression-free survival (PFS) was evaluated using Cox proportional hazards regression analysis, with gene expression as a continuous variable or dichotomized by median. An independent breast cancer cohort from the Preoperative Palbociclib (POP) Clinical Trial (ClinicalTrials.gov identifier: NCT02008734) was used for validation, in 61 patients with primary breast cancer treated with 2 weeks of palbociclib.

RESULTS

In the PALOMA-3 trial, 302 patients had tumor tissue analyzed (palbociclib arm, 194 patients; placebo arm, 108 patients). Palbociclib efficacy was lower in patients with high versus low cyclin E1 (CCNE1) mRNA expression (median PFS: palbociclib arm, 7.6 v 14.1 months; placebo arm, 4.0 v 4.8 months, respectively; interaction P unadjusted = .00238; false discovery rate–adjusted P = .0238). CCNE1 mRNA was more predictive in metastatic than in archival primary biopsy tissue samples. No significant interaction was found between treatment and expression levels of CDK4, CDK6, cyclin D1, and RB1. Palbociclib was efficacious in both luminal A and luminal B tumors. High CCNE1 mRNA expression was associated with poor antiproliferative activity of palbociclib in the POP trial (P = .005).

CONCLUSION

Addition of palbociclib to fulvestrant demonstrated efficacy in all biomarker groups, although high CCNE1 mRNA expression was associated with relative resistance to palbociclib.

Abstract PD3-06: Neratinib + fulvestrant for HER2-mutant, HR-positive, metastatic breast cancer: Updated results from the phase 2 SUMMIT trial

Background: HER2 mutations define a rare subset of metastatic breast cancer (MBC) with a unique mechanism of oncogenic addiction to HER2 signaling. Neratinib, an irreversible pan-HER tyrosine kinase inhibitor, has demonstrated single-agent clinical activity in HER2-mutant MBC. In HER2-mutant, HR+ MBC, neratinib + fulvestrant (N+F) appears synergistic vs single-agent neratinib, possibly due to more complete inhibition of bi-directional signaling between HER2 and estrogen receptors. Here we describe interim efficacy results of the expanded HER2-mutant, HR+ MBC cohort treated with N+F from SUMMIT (NCT01953926).

Methods: HR+ MBC patients (pts) with HER2 mutations documented by local testing received oral neratinib 240mg qd and intramuscular fulvestrant (labeled dose). Intensive loperamide prophylaxis was mandatory during cycle 1. Efficacy endpoints include objective response rate at week 8 (ORR8); confirmed objective response rate (ORR); clinical benefit rate (CBR); duration of response (DOR); progression-free survival (PFS); response was assessed by RECIST 1.1 and/or PET Response Criteria. Genomic profiling from fresh/archival tumor tissues and/or plasma cfDNA was performed retrospectively by next-generation sequencing (MSK-IMPACT).

Results: As of 18 May 2018, 46 HER2-mutant HR+ MBC pts have been treated with N+F. Most pts were pretreated, with 91% having received prior anti-cancer medication for MBC (range 0–10). ORR was 33% and median DOR in the 15 pts with a confirmed response was 9.2 months (95% CI 3.9–18.5). Twenty-four pts had prior fulvestrant exposure, and 19 had received prior CDK4/6i-based therapy. Clinical activity was observed with ORRs of 17% and 26% in prior fulvestrant-treated and prior CDK4/6i-treated pts, respectively. ORRs by HER2 mutation were: V777L 63% (5/8 pts); S310F/Y 67% (4/6 pts); G778_P780dup 50% (3/6 pts). Diarrhea was the most common adverse event (grade 3, 24%; grade 4, 0%). Median cumulative duration of grade 3 diarrhea was 3 days. There were no treatment discontinuations due to diarrhea.

 Neratinib + fulvestrantOutcomeaAll patients (N=46)Prior fulvestrant (N=24)Prior CDK4/6i-based therapy (N=19)ORR8 – n (%)19 (41.3)8 (33.3)7 (36.8)95% CI27.0–56.815.6–55.316.3–61.6ORR – n (%)15 (32.6)4 (16.7)5 (26.3)95% CI19.5–48.04.7–37.49.1–51.2DOR for each responder, months 5.6b; 9.2; 9.6b; 18.55.6b; 5.7b; 9.3; 9.6b; 12.9bCBR – n (%)27 (58.7)11 (45.8)9 (47.4)95% CI43.2–73.025.6–67.224.4–71.1Median (95% CI) time to event,c monthsPFS3.9 (3.6–5.7)3.7 (3.5–12.8)3.9 (1.9–NA)DOR9.2 (3.9–18.5)NANAaFor pts with both RECIST- and PET-evaluable lesions, the best of either RECIST or PET response was used to determine response; the earliest progression by RECIST or PET was used for progression; bPt has not progressed; cKaplan-Meier analysis; NA, not applicable

Conclusions: N+F demonstrates encouraging clinical activity with durable responses in heavily pretreated pts with HER2-mutant, HR+ MBC. Of note, responses were observed in pts who had received prior fulvestrant or CDK4/6 inhibitors. No new safety signals were identified; the rate of diarrhea was similar to single-agent neratinib and not dose limiting. Updated data after additional follow-up and genomic data will be presented.

Citation Format: Smyth LM, Piha-Paul SA, Saura C, Loi S, Lu J, Shapiro GI, Juric D, Mayer IA, Arteaga C, de la Fuente M, Brufksy AM, Mau-Sørensen M, Arnedos M, Moreno V, Sohn J-H, Schwartzberg L, Gonzàlez-Farré X, Cervantes A, Mann G, Shahin S, Cutler, Jr. RE, Eli LD, Xu F, Bagulho T, Lalani AS, Bryce R, Solit DB, Hyman DM, Meric-Bernstam F, Baselga J. Neratinib + fulvestrant for HER2-mutant, HR-positive, metastatic breast cancer: Updated results from the phase 2 SUMMIT trial [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD3-06.

Abstract P5-21-11: Benefit from palbociclib and fulvestrant based on previous fulvestrant and/or everolimus treatment. Based on a cohort of over 200 patients treated in a French compassionate program

Background: CDK4/6 inhibitors have been approved in the recent years for the treatment of advanced hormone receptor-positive breast cancer. For patients with resistance to previous endocrine therapy, the approval is based on the results of the PALOMA-3 trial testing palbociclib in addition to fulvestrant observing a progression-free survival (PFS) of 9.2 months. Nevertheless, in this study no previous treatment with fulvestrant was allowed and no information had been reported of efficacy after everolimus administration.

Patients and methods: We collected information from patients treated with palbociclib + fulvestrant in the context of a French compassionate access. We aimed at determining the benefit of this treatment in a real population to provide information about PFS in non-selected patients as well as efficacy of palbociclib and fulvestrant in patients previously treated with fulvestrant and/or everolimus. Median PFS were assessed by Kaplan-Meier survival analysis and compared with log-rank test.

Results: 206 patients were identified from 5 institutions. Mean age at treatment was 61 years (range 28 – 85). 55% presented with visceral disease. Lines at where palbociclib + fulvestrant treatment was administered were as follows: 1% 1st line, 8.3% 2nd line, 19.4% 3rd line, 13.6% 4th line, 10.2% 5th lignes and the remaining 47.6% had received ≥6 lines (median: 5 lines, range 1 to 15).

A total of 48% patients had previously been treated with fulvestrant. In a subsample of patient where the information was available (n=146), 67.8% patients had received everolimus in combination with endocrine therapy before palbociclib administration.

A total of 77 patients were still on treatment. Median PFS on fulvestrant-palbociclib treatment at the date of data cut-off was of 5.46 months (95% CI; 4.6 to 6.6 months). In a univariate analysis, there were no significant differences in median PFS for patients treated or not with previous fulvestrant, suggesting a potential effect of palbociclib to recover sensitivity to fulvestrant (4.7 months for previous fulvestrant treatment [95% CI 4.07 - 6.3 months] vs 6.1 months for no previous fulvestrant [95% CI; 6.3 - 8.02 months], p=0.3559).

Similarly, in the subsample of n=146 patients where information about previous everolimus treatment was available at data cut-off, benefit from palbociclib-fulvestrant was not affected by previous everolimus treatment (median PFS 4.8 months for previously treated [95% CI; 4.01 -7.8 months] vs 5.4 months for the untreated everolimus group [95% CI; 4.07 - 9.59 months], p=0.374).

Conclusions: Fulvestrant-palbociclib in the real life is associated with a median PFS of 5.5 months, which is below the results provided in the PALOMA-3 trial, reflecting a much more advanced population. Importantly, neither previous everolimus treatment nor fulvestrant therapy affected benefit from fulvestrant-palbociclib in this population in univariate analyses suggesting a potential recovery of fulvestrant sensitivity with CDK4/6 inhibition. Results from multivariate analyses and more detailed information about patients' characteristics and benefit from previous therapies will be provided.

Citation Format: Arnedos M, Rusquec P, Morelle M, Lebreton C, Jacquet E, Emile G, Aires J, Debled M, Frenel J-S, Augereau P, Cheaib B, Levy C, Bachelot T. Benefit from palbociclib and fulvestrant based on previous fulvestrant and/or everolimus treatment. Based on a cohort of over 200 patients treated in a French compassionate program [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-21-11.

Abstract 1008: Gain-of-function kinase library screen identifies FGFR1 amplification as a mechanism of resistance to antiestrogens and CDK4/6 inhibitors in ER+ breast cancer

The CDK4/6 inhibitor palbociclib was recently approved in combination with endocrine therapy for treatment of ER+ metastatic breast cancer. The goal of this study was to discover mechanisms of resistance to ER antagonists alone and in combination with CDK4/6 inhibitors. To achieve this goal, we used lentiviral vectors to individually express 559 human kinase open reading frames (ORFs) in ER+ MCF7 human breast cancer cells treated with fulvestrant ± the CDK4/6 inhibitor ribociclib (Novartis). In MCF7 cells treated with fulvestrant alone or with ribociclib, we identified 21 and 17 kinases, respectively, which induced a &gt;30% increase in cell viability compared to control cells; 11 of these kinases overlapped in both treatment groups. In a secondary screen, MCF7 cells were stably transduced with V5-tagged lentiviruses expressing the positive ‘hits’ for treatment with fulvestrant/ribociclib. Five of 11 kinases (FGFR1, FRK, HCK, FGR, CRKL) were confirmed to induce resistance to fulvestrant/palbociclib and fulvestrant/ribociblib. Survey of TCGA for copy number alterations and/or expression of these five genes showed only FGFR1 to be amplified/overexpressed in 17% of ER+ breast cancers. Experiments in vitro showed that ER+/FGFR1-amplified (amp) MDA-134, CAMA-1 and HCC1500 human breast cancer cells and MCF7 cells stably transduced with FGFR1 were relatively resistant to estrogen deprivation, fulvestrant and fulvestrant/palbociclib compared to non-FGFR1 amp MCF7 cells. This resistance was abrogated by treatment with the FGFR tyrosine kinase inhibitor (TKI) lucitanib. Treatment with fulvestrant or palbociclib, each alone, modestly delayed growth of ER+/FGFR1-amp breast cancer patient-derived xenografts (PDX) established in nude mice. However, addition of the FGFR TKI erdafitinib to fulvestrant/palbociclib resulted in marked PDX regressions in all mice without associated toxicity. Treatment of FGFR-amp cells with FGF-2 strongly induced CCND1 (cyclin D1) expression. Downregulation of CCND1 with CCND1 RNAi oligonucleotides or kinase inhibition with erdafitinib restored sensitivity of FGFR1-amp cells to fulvestrant/palbociclib. Conversely, overexpression of CCND1 in MCF7 cells induced resistance to estrogen deprivation and fulvestrant ± palbociclib. At this time, we are examining whether FGFR1 amplification measured by FISH correlates with maintenance of proliferation (Ki67) in 110 patients with ER+/HER2- breast cancer treated with palbociclib for 14 days immediately before surgery (Arnedos et al. ASCO 2016). In summary, using a gain-of-function ORF kinome screen, we identified FGFR1 amplification as a mechanism of resistance to anti-ER therapies ± CDK4/6 inhibitors. Based on these data we propose FGFR inhibitors should be tested in combination with ER antagonists and CDK4/6 inhibitors in patients with ER+/FGFR amplified breast cancer.

Citation Format: Luigi Formisano, Yao Lu, Valerie M. Jansen, Joshua A. Bauer, Ariella B. Hanker, Melinda E. Sanders, Paula González-Ericsson, Sunkyu Kim, Monica Arnedos, Fabrice André, Carlos L. Arteaga. Gain-of-function kinase library screen identifies FGFR1 amplification as a mechanism of resistance to antiestrogens and CDK4/6 inhibitors in ER+ breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1008. doi:10.1158/1538-7445.AM2017-1008

Abstract LB-103: Landscape of somatic ERBB2 Mutations: Findings from AACR GENIE and comparison to ongoing ERBB2 mutant basket study

Background: AACR GENIE is an international data-sharing project that aggregates clinical-grade cancer genomic data. As a demonstration of utility, we evaluated the landscape of ERBB2 mutations in the first 18,486 patients included in this registry and compared it to the first 100 patients enrolled in an ongoing international Phase 2 SUMMIT ‘basket’ study of the pan-HER inhibitor neratinib in ERBB2 mutant solid tumors (NCT01953926). Results: ERBB2 mutations were identified in 2.8% (519/18,486) of patients in the GENIE cohort and observed at all participating centers. In total, there were 482 missense, 66 indels, 19 truncating mutations, and 14 structural variants. A total of 263 unique missense mutations were observed including 12 at previously identified hotspots which accounted for 69.2% of all missense mutations. 35 unique cancer types were represented. The tumor types with the highest proportion of ERBB2 mutations were bladder (12.8%, 82/641), breast (3.9%, 87/2230), colorectal (3.3%, 70/2102), and NSCLC (3%, 90/3006). Among patients with copy number data available (91%) 11% had concurrent ERBB2 amplification, most often in breast cancer. The most frequently observed alterations in ERBB2, adjusted for differing exon coverage between panels, was S310F/Y in 0.46% of the GENIE cohort (12.6% of samples with ERBB2 alterations), Y772_A775dup in 0.21% (6.9%), R678Q in 0.17% (4.5%), L755S in 0.16% (5.2%), V777L in 0.12% (3.8%), and V842I in 0.09% (3.1%). The distribution of specific ERBB2 variants differed significantly by tumor type with exon 20 insertions being most common in NSCLC (44.4%, 40/90), L755S (18.9%, 11/92) in breast, S310F/Y (26.9%, 28/104) in bladder, and V842I (13.9%, 10/72) in colorectal cancer. Structural variants included intragenic deletions (n=4) and fusions involving various partners including GRB7 (n=2), and one each of C1orf87, PPIL6, HEXIM2, THRA, ASIC2, BCA3, WIPF2. The frequencies of ERBB2 mutant cancer types observed in the GENIE cohort were generally comparable to those enrolled to the neratinib basket study including NSCLC (17 vs 22%, respectively), breast (16.4 vs 24%), bladder (15.5 vs 14%), colorectal (13.2 vs 17%), and endometrial (4.2 vs 6%). At the variant level, S310F/Y was less prevalent in GENIE compared to the neratinib study (12.6 vs 24%) while all other mutations were generally similar including L755S (5.2 vs 9%), R678Q (4.5 vs 2%), Y772_A775dup (6.9 vs 13%), V777L (3.8 vs 9%), and V842I (3.1 vs 6%). Conclusion: GENIE confirms that a diversity of ERBB2 mutations are prevalent across a variety of tumor types in patients with advanced cancer. The genomic landscape of ERBB2 mutations was largely similar in the population based GENIE cohort and the neratinib SUMMIT study, providing the first direct evidence that basket study enrollment accurately reflects the true landscape of the target alteration.

Citation Format: Alison Schram, Helen H. Won, Fabrice Andre, Monica Arnedos, Funda Meric - Bernstam, Philippe L. Bedard, Kenna R. Shaw, Hugo Horlings, Christine Micheel, Ben Ho Park, Grace Mann, Alshad S. Lalani, Lillian Smyth, David B. Solit, Deborah Schrag, Mia A. Levy, Barrett J. Rollins, Mark Routbort, Charles L. Sawyers, Eva Lepisto, Michael F. Berger, David M. Hyman, on behalf of the AACR Project GENIE Consortium. Landscape of somatic ERBB2 Mutations: Findings from AACR GENIE and comparison to ongoing ERBB2 mutant basket study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-103. doi:10.1158/1538-7445.AM2017-LB-103

Longitudinal serum metabolomics evaluation of trastuzumab and everolimus combination as pre-operative treatment for HER-2 positive breast cancer patients

The mammalian target of rapamycin complex 1 (mTORC1) is an attractive target for HER-2 positive breast cancer therapy because of its key role in protein translation regulation, cell growth and metabolism. We present here a metabolomic investigation exploring the impact of mTOR inhibition on serum metabolic profiles from patients with non-metastatic breast cancer overexpressing HER-2.

Baseline, treatment-related and post-treatment serum samples were analyzed for 79 patients participating in the French clinical trial RADHER, in which randomized patients with HER-2 positive breast cancer received either trastuzumab alone (arm T) or a trastuzumab and everolimus combination (arm T+E). Longitudinal series of NMR serum metabolic profiles were exploited to investigate treatment effects on the patients metabolism over time, in both group.

Trastuzumab and everolimus combination induces faster changes in patients metabolism than trastuzumab alone, visible after only one week of treatment as well as a residual effect detectable up to three weeks after ending the treatment. These metabolic fingerprints highlight the involvement of several metabolic pathways reflecting a systemic effect, particularly on the liver and visceral fat. Comparison of serum metabolic profiles between the two arms shows that everolimus, an mTORC1 inhibitor, is responsible for host metabolism modifications observed in arm T+E.

In HER-2 positive breast cancer, our metabolomic approach confirms a fast and persistent host metabolism modification caused by mTOR inhibition.

Abstract PD1-08: High-throughput genome analysis and therapeutic decision for patients with HER2-negative metastatic breast cancer: First feasibility and molecular results of the randomized phase II study SAFIR02 BREAST (UCBG-0105/1304)

Background A genomic-driven therapeutic strategy in metastatic breast cancer (MBC) was recently demonstrated as feasible in the clinical practice, but its actual impact on patient outcome remains elusive. SAFIR02 study is an ongoing national multicentric phase II randomized trial evaluating targeted therapies matching specific genomic alterations (GA) administered as maintenance after objective response and/or stable disease obtained with chemotherapy in HER2-negative MBC patients. This analysis reports on feasibility of the procedure and the rate of identified actionable targets.

Methods Eligible MBC patients (PS=0/1, first- or second-line of chemotherapy, HER2-negative/hormone receptor (HR)-negative or endocrine resistant HR-positive; measurable per RECIST 1.1; accessible to tumor biopsy; no bone metastases-only disease, no major organ dysfunction) were subjected to tumor biopsy for genomic analysis (CGH arrays, Affymetrix Cytoscan; NGS, Ion Torrent PGM, AmpliSeq, panel of around 50 genes). Actionable GA were identified and corresponding targeted therapies were proposed by a multidisciplinary tumor board (MTB). Patients received cytotoxic-based treatment at physician's choice and those with stable or responding disease after 6 to 8 cycles (or at least 4 if stopped for toxicity reason) and targetable GA, were offered randomization between targeted therapy or chemotherapy maintenance until progression or intolerance (main study). Since January 2016, an amendment was made to propose to patients without targetable alteration a randomization between anti-PD-L1 (MEDI4736) or standard chemotherapy maintenance (substudy).

Results Between March 2014 and May 2016, 457 patients have been enrolled at 21 centers. Genomic analyses could not be obtained in 107 cases (23%) due to either biopsy failure (n= 40; 9%) or low cellularity (n=67; 14%). Of the 307 patients reviewed by the MTB, 197 (64%) had an actionable GA, including PIK3CA-PIK3CB-PIK3R1 (n=51), FGF4 or FGFR1/2 (n= 42), BRCA1/2 (n=15), AKT1/2/3 (n=13), BRAF/KRAS/NRAS (n=13), HER2/3 (n=10), NF1-FRS2 (n=10), MTOR-RPTOR-TSC2 (n=8), PTEN (n=7), STK11 (n=7), IGF1R (n=7), EGFR (n=5). Therapeutic proposals by MTB included AZD5363 (n=71), AZD4547 (n=42), AZD2014 (n=23), selumetinib (n=23), olaparib (n=16), AZD8931 (n=15), vandetanib (n=5), bicalutamide (n=2). In an exploratory analysis involving 157 patients, the rate of targeted therapy proposal by MTB markedly differed between triple-negative patients (TNBC; 24 of 48, 50%) and HER2-negative/HR-positive patients (92 of 109, 84%; p=6.14. 10-6, Chi-2 test). At the time of the analysis, 85 patients have been randomized (main study, 68; substudy, 17). Causes of randomization failure (n=108) included disease progression (n=45) or death (n=25), non-eligibility criteria (n=27), patient/physician's decision (n=11).

Conclusion A large number of patients had identified targetable GA. Of note, the rate of targeted therapeutic proposal was significantly lower in TNBC than in HER2-negative/HR-positive patients. Rapidly progressing disease may impede ultimate randomization.

Citation Format: Gonçalves A, Bachelot T, Lusque A, Arnedos M, Campone M, Bièche I, Lacroix L, Pierron G, Dalenc F, Filleron T, Sablin M-P, Jimenez M, Ferrero J-M, Lefeuvre-Plesse C, Bonnefoi H, Attignon V, Soubeyran I, Jezequel P, Commo F, André F. High-throughput genome analysis and therapeutic decision for patients with HER2-negative metastatic breast cancer: First feasibility and molecular results of the randomized phase II study SAFIR02 BREAST (UCBG-0105/1304) [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr PD1-08.

Mutational Profile of Metastatic Breast Cancers: A Retrospective Analysis

BACKGROUND

Major advances have been achieved in the characterization of early breast cancer (eBC) genomic profiles. Metastatic breast cancer (mBC) is associated with poor outcomes, yet limited information is available on the genomic profile of this disease. This study aims to decipher mutational profiles of mBC using next-generation sequencing.

METHODS AND FINDINGS

Whole-exome sequencing was performed on 216 tumor-blood pairs from mBC patients who underwent a biopsy in the context of the SAFIR01, SAFIR02, SHIVA, or Molecular Screening for Cancer Treatment Optimization (MOSCATO) prospective trials. Mutational profiles from 772 primary breast tumors from The Cancer Genome Atlas (TCGA) were used as a reference for comparing primary and mBC mutational profiles. Twelve genes (TP53, PIK3CA, GATA3, ESR1, MAP3K1, CDH1, AKT1, MAP2K4, RB1, PTEN, CBFB, and CDKN2A) were identified as significantly mutated in mBC (false discovery rate [FDR] < 0.1). Eight genes (ESR1, FSIP2, FRAS1, OSBPL3, EDC4, PALB2, IGFN1, and AGRN) were more frequently mutated in mBC as compared to eBC (FDR < 0.01). ESR1 was identified both as a driver and as a metastatic gene (n = 22, odds ratio = 29, 95% CI [9-155], p = 1.2e-12) and also presented with focal amplification (n = 9) for a total of 31 mBCs with either ESR1 mutation or amplification, including 27 hormone receptor positive (HR+) and HER2 negative (HER2-) mBCs (19%). HR+/HER2- mBC presented a high prevalence of mutations on genes located on the mechanistic target of rapamycin (mTOR) pathway (TSC1 and TSC2) as compared to HR+/HER2- eBC (respectively 6% and 0.7%, p = 0.0004). Other actionable genes were more frequently mutated in HR+ mBC, including ERBB4 (n = 8), NOTCH3 (n = 7), and ALK (n = 7). Analysis of mutational signatures revealed a significant increase in APOBEC-mediated mutagenesis in HR+/HER2- metastatic tumors as compared to primary TCGA samples (p < 2e-16). The main limitations of this study include the absence of bone metastases and the size of the cohort, which might not have allowed the identification of rare mutations and their effect on survival.

CONCLUSIONS

This work reports the results of the analysis of the first large-scale study on mutation profiles of mBC. This study revealed genomic alterations and mutational signatures involved in the resistance to therapies, including actionable mutations.

The challenge of rapid diagnosis in oncology: Diagnostic accuracy and cost analysis of a large-scale one-stop breast clinic

PURPOSE

Rapid diagnosis is a key issue in modern oncology, for which one-stop breast clinics are a model. We aimed to assess the diagnosis accuracy and procedure costs of a large-scale one-stop breast clinic.

PATIENTS AND METHODS

A total of 10,602 individuals with suspect breast lesions attended the Gustave Roussy's regional one-stop breast clinic between 2004 and 2012. The multidisciplinary clinic uses multimodal imaging together with ultrasonography-guided fine needle aspiration for masses and ultrasonography-guided and stereotactic biopsies as needed. Diagnostic accuracy was assessed by comparing one-stop diagnosis to the consolidated diagnosis obtained after surgery or biopsy or long-term monitoring. The medical cost per patient of the care pathway was assessed from patient-level data collected prospectively.

RESULTS

Sixty-nine percent of the patients had masses, while 31% had micro-calcifications or other non-mass lesions. In 75% of the cases (87% of masses), an exact diagnosis could be given on the same day. In the base-case analysis (i.e. considering only benign and malignant lesions at one-stop and at consolidated diagnoses), the sensitivity of the one-stop clinic was 98.4%, specificity 99.8%, positive and negative predictive values 99.7% and 99.0%. In the sensitivity analysis (reclassification of suspect, atypical and undetermined lesions), diagnostic sensitivity varied from 90.3% to 98.5% and specificity varied from 94.3% to 99.8%. The mean medical cost per patient of one-stop diagnostic procedure was €420.

CONCLUSIONS

One-stop breast clinic can provide timely and cost-efficient delivery of highly accurate diagnoses and serve as models of care for multiple settings, including rapid screening-linked diagnosis.

Concordance between HER-2 status determined by qPCR in Fine Needle Aspiration Cytology (FNAC) samples compared with IHC and FISH in Core Needle Biopsy (CNB) or surgical specimens in breast cancer patients

Determining the status of HER2-neu amplification and overexpression in breast cancer is crucial for prognosis but mostly for treatment purposes. Standard techniques include the determination of IHC in combination with in situ hybridization techniques to confirm a HER2-neu amplification in case of IHC2+ using either a core-needle biopsy or a surgical specimen. qPCR has been also demonstrated to be able to determine HER2 status, mostly in core biopsies or in surgical specimens. Fine-needle aspiration is a reliable, quicker and less invasive technique that is widely used for diagnosis of invasive breast cancer. In this study, we assessed the performance of qPCR in invasive breast carcinomas to determine HER2-neu status by using fine-needle aspiration samples and comparing to standard IHC and FISH. From a total of 154 samples from patients who had nodular breast lesions and attended the 1-day-stop clinic at the Gustave Roussy from March 2013 to October 2014, qPCR was able to determine the HER2 status in a mean of 3.7 days (SD 3.1). The overall concordance with standard HER2-testing was very high: 97% (95% CI 0.94 to 0.99); sensitivity was 96% (0.87-1), specificity 98% (0.95-1) and positive and negative predictive values 88% (0.75-1) and 99% (0.98-1), respectively. In conclusion, our study demonstrates that qPCR performed using fine-needle aspiration samples from a primary tumour is a reliable and fast method to determine HER2/neu status in patients with early breast cancer.

Abstract LB-353: Mutational profile of metastatic breast cancers using whole-exome sequencing: a retrospective analysis of 216 samples from SAFIR01 / 02 / SHIVA / MOSCATO trials

Background: Major advances have been achieved in the understanding of breast cancer biology using high throughput technologies at the DNA and RNA levels. Most of these advances were made in early breast cancers (eBC) which are cured in about 80% of the cases. Nevertheless, little is known about metastatic breast cancers (mBC) which remain lethal in most of the cases.

Methods: Whole-exome sequencing was performed on 216 tumour-normal pairs from mBC patients who underwent a biopsy in the context of the SAFIR01/SAFIR02/SHIVA or MOSCATO prospective trials. TCGA dataset (n = 772) was used to assess frequency of mutations in eBC.

Findings: Twelve genes (TP53, PIK3CA, GATA3, ESR1, MAP3K1, CDH1, AKT1, MAP2K4, RB1, PTEN, CBFB, CDKN2A) were identified as drivers using MutSig algorithm (FDR&lt;0.1). Eight genes (ESR1, FSIP2, FRAS1, OSBPL3, EDC4, PALB2, IGFN1, AGRN) were more frequently mutated in mBC as compared to eBC (TCGA, FDR&lt;0.01). HR+/Her2- mBC presented a high prevalence (6.3%) of mutations on genes located on mTOR pathway (TSC1, TSC2) as compared to HR+/Her2- eBC (0.7%, p = 0.0004). A subset of HR+/Her2- mBC (n = 17, 12%) presented a high mutational load (&gt;150 non-synonymous mutations). This subset was observed in 2% of early breast cancers (TCGA, p = 7.1e?06). The prevalence of this subset increased with the time from diagnosis of metastasis to biopsy. Highly mutated HR+/Her2- mBC (n = 17) presented higher rate of PIK3CA mutations (n = 12, 70%), high number of neoantigens, an APOBEC mutational signature and a poor outcome (multivariate analysis, HR = 4.68, 95%CI: 1.8-12.1, p = 0.001).

Interpretation: Whole exome sequencing of metastatic breast cancers identifies a subset of HR+/Her2- mBC who present a high mutational load. RB1, PALB2 and TSC1/2 mutations were found enriched in either mBC or HR+ mBC.

Fundings: Breast Cancer Research Foundation, Fondation ARC, Fondation Lombard-Odier “Philanthropia”, Odyssea, Operation Parrains Chercheurs, Dassault Foundation, French NCI: INCa-DGOS-INSERM 6043

Citation Format: Maud Kamal, Celine Lefebvre, Thomas Bachelot, Thomas Filleron, Marion Pedrero, Mario Campone, Jean-Charles Soria, Christophe Massard, Christelle Levy, Monica Arnedos, Julie Garrabey, Yannick Boursin, Marc Deloger, Yu Fu, Frederic Commo, Veronique Scott, Ludovic Lacroix, Emmanuel Martin, Veronique Dieras, Anthony Goncalves, Jean-Marc Ferrero, Gilles Romieu, Laurence Vanlemmens, Marie-Ange Mouret-Reynier, Jean-christophe Thery, Pierre Kerbrat, Severine Guiu, Florence Dalenc, Gilles Clapisson, Hervé Bonnefoi, Martha Jimenez, Christophe Le Tourneau, Fabrice Andre. Mutational profile of metastatic breast cancers using whole-exome sequencing: a retrospective analysis of 216 samples from SAFIR01 / 02 / SHIVA / MOSCATO trials. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-353.