Rodriguez, AA

Abstract Background: Previous failed trials of anti-EGFR therapy (TBCRC001) in breast cancer have not directly assessed EGFR amplification instead relying on pathway activation surrogates. Previous studies have examined EGFR amplification primarily retrospectively for research purposes without being part of a standard diagnostic evaluation. We evaluated 5,606 clincally advanced breast cases for which comprehensive genomic profiling was performed in the course of clinical care to identify EGFR altered mBC cases. Methods: DNA was extracted from 40 microns of FFPE sections from 5,605 mBC. Comprehensive genomic profiling (CGP) was performed using a hybrid-capture, adaptor ligation based next generation sequencing assay of up to 236 or 315 genes to a mean coverage depth of >600X. The results were analyzed for base substitutions, short insertions and deletions, selected rearrangements, and copy number changes. Results: 155 (2.7%) of 5,605 mBC featured EGFR alterations. 126 (10.6%) featured EGFR amplification, and 27 (2.2%) featured ERBB2 subs/indels, with no cases harboring both amplification and another GA of EGFR. These patient (pts) had a median age of 55 years (range 30 to 78). For EGFR altered cases, specimens utilized for CGP included 59 (38%) from the patient's primary BC and 93 (60%) from metastatic sites including liver (14%), lymph node (14%), lung (8%), soft tissue (6%), skin (5%) and with information not available for 3 cases. 75 (48%) mBC were submitted as IDC, 69 (45%) as breast carcinoma NOS, 5 (3 %) as metaplastic BC, and 7 (5%) as other mBC. For the 126 EGFR amplified breast patients, quantitative estimation of EGFR copy number ranged from 6 to 380 copies, with a median of 12 copies. A patient with heavily pretreated case and whose TNBC harbored 32 copies of EGFR was begun on erlotinib and has experienced a 20 months ongoing complete response to erlotinib, and will be presented as will other outcomes and biomarker characterization of these cases. Conclusions: Given anecdotal evidence that mBC is responsive to anti-EGFR targeted therapies, prediction of benefit from such therapies may be linked to sensitive and specific detection of EGFR alteration in mBC cases. This study demonstrates a 2.7% EGFR alteration rate of mBC, with a striking median copy number of 12 for the subset of EGFR amplified cases. Given these findings along with anecdotal report of patient benefit, utilization of CGP in the course of clinical care or for clinical trials for mBC may help optimize treatement with targeted therapies for these patients including the direction of anti-EGFR monotherapy to EGFR altered patients. Citation Format: Ali SM, Wang K, Johnson A, Rodriguez AA, Elvin JA, Vergilio J-A, Suh JH, Chumsri S, Morosini D, Yelensky R, Lipson D, Chmielecki J, Miller VA, Ross JS, Chang J, Stephens PJ. EGFR genomic alterations in 5,605 cases of refractory and metastatic breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-03-02.

Abstract Background: Hsp90 is a molecular chaperone protein required for the stabilization and activation of many proteins, referred to as Hsp90 ‘clients’, such as HER2, HIF1-a, EGFR, ER, PI3K, AKT, P53 and VEGFR. The drug candidate, ganetespib is a novel triazolone inhibitor of Hsp90, with over 700 patients treated to date. Ganetespib has shown activity in preclinical models of HER2+, ER+/PR+ and TNBC. Early clinical trials documented ganetespib single agent activity in heavily pretreated HER2+ and TNBC patients. Ganetespib has been well tolerated in clinical trials with a favorable safety profile. This efficacy-screening study is designed to provide further evidence of ganetespib activity and identify potentially predictive biomarkers in metastatic breast cancer (BC). Methods: The ENCHANT-1 Trial is an international, first-line 2-cohort Phase 2 study in BC patients: Cohort A, HER2 amplified (n = 35), and Cohort B, TNBC (n = 35). Patients who present with previously untreated metastatic disease are eligible for treatment with ganetespib at 150 mg/m2 twice weekly on 3 out of 4 wks, for a total of up to 12 wks. Primary endpoint: ORR assessed using RECIST1.1 criteria. Key secondary endpoints include metabolic response as assessed by PET/CT at wk 3 utilizing modified EORTC criteria. Disease progression (PD) at wk 3 by PET imaging indicates discontinuation of study therapy, and is performed to quickly offer patients with metabolic PD a standard of care treatment. The study is designed as Simon 2-stage requiring at least one OR in 15 patients for the respective cohort to expand to 35 patients. A Steering Committee is established to oversee the overall study and review the interim results. Results: The study was initiated in 23 centers globally. At the time of submission, a total of 17 patients had been enrolled; TNBC (n = 15) and HER2 (n = 2). Here we report the interim analysis in the TNBC cohort. The median age was 54 years (range 30 -77) with ECOG PS 0 (n = 7/15). Most patients (n = 9) presented with de novo metastatic disease. 5 patients were not evaluable for PET assessment (3 had not yet reached wk 3 and 2 withdrawn before wk 3 for clinical progression), and 9 patients were not evaluable for objective response at wk 6 (3 withdrawn before or at wk 3 for clinical progression and 6 had not yet reached wk 6 evaluation). In the 10 patients with evaluable PET imaging, 9 patients achieved metabolic (m) response (2 mPR, 4 mSD with dominant tumor shrinkage and 3 SD) and one patient with mPD. In the 6 patients evaluable for OR at wk 6, one patient achieved PR, 2 SD and 3 PD. Treatment with ganetespib was well tolerated; the most common AEs were mild or moderate diarrhea (8/15, 53%), fatigue (5/15, 33%), decreased appetite (4/15, 27%), insomnia (4/15, 27%), and nausea (4/15, 27%). Conclusion: Ganetespib single agent was generally well tolerated and showed anti-tumor activity TNBC patients as early as 3 weeks following treatment. PET seems to be a good tool to screen antitumor activity of new agents in early settings rather that in heavily pretreated patients. The TNBC cohort has met the protocol criteria for proceeding to stage 2. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-16-23.