Abstract CT225: Ado-trastuzumab emtansine forHER2amplified or HER2 overexpressed cancers: A phase II “basket” trial

Background: The use of therapies targeting the human epidermal growth factor receptor 2 (HER2, ERBB2) has transformed care in breast and gastric cancers. HER2 amplification has emerged as a therapeutic target in 2-5% of lung cancers, 6% of bladder cancers, 5-12% of endometrial cancers, and 2-5% of ovarian and colorectal cancers. High level HER2 protein overexpression by immunohistochemistry correlates with HER2 amplification. Ado-trastuzumab emtansine is an antibody drug conjugate linking the HER2 targeted monoclonal antibody trastuzumab, with the cytotoxic anti-microtubule drug emtansine. This agent improves response and survival in patients with HER2 amplified or HER2 overexpressed breast cancers. We hypothesize that ado-trastuzumab emtansine will be effective in any tumor with HER2 amplification or overexpression, regardless of the primary site. Methods/Design: This phase II “basket” trial at Memorial Sloan Kettering (MSK) will evaluate ado-trastuzumab emtansine across 4 cohorts of patients with HER2 amplified or HER2 overexpressed advanced lung, bladder, endometrial, and other cancers. All patients will receive ado-trastuzumab emtansine at 3.6 mg/m 2 IV every 21 days until disease progression or unacceptable toxicity. The primary endpoint is objective response rate (ORR). Patients will be molecularly selected primarily through the MSK-Integrated Mutation Profiling of Actionable Cancer Targets (MSK-IMPACT), where all patients with advanced cancers can have tumor next generation sequencing (NGS) performed with a capacity to sequence 15,000 tumors each year. MSK-IMPACT uses the Illumina HiSeq platform to screen for potentially actionable genetic alterations, including single base substitutions, indels, copy number alterations and selected fusions across 341 cancer-related genes, including HER2 amplification. HER2 amplification assessment by our NGS assay correlates well with amplification by in-situ hybridization, is less operator-dependent and is performed concurrently with the mutation profile. In the first 6 months since introducing MSK-IMPACT into routine patient care, we have already identified HER2 amplification in 7 of 227 (3%) lung cancers sequenced, 4 of 67 (6%) bladder cancers sequenced, and 2 of 50 (4%) endometrial cancers sequenced. Using a Simon optimal two-stage design, a one-sided Type I error rate α at 10% and power of 80%, a true ORR ≤ 10% will be considered unacceptable (null hypothesis) whereas a true ORR ≥ 30% will merit further study (alternative hypothesis). In each cohort, 7 patients will be accrued in the first stage; if there are no responses observed, the cohort will be closed. Otherwise, 11 additional patients will be accrued for second stage. A cohort will be deemed worthy of further investigation if ≥4 responses are observed in 18 patients. Exploratory analysis will examine the concordance among the HER2 biomarkers: gene amplification, protein overexpression and gene mutation. Citation Format: Bob T. Li, Marjorie Zauderer, Jamie Chaft, Alexander Drilon, Juliana Eng, Camelia Sima, Vicky Makker, Gopa Iyer, Yelena Janjigian, David Hyman, Maria Arcila, Jose Baselga, Mark G. Kris. Ado-trastuzumab emtansine for HER2 amplified or HER2 overexpressed cancers: A phase II “basket” trial. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr CT225. doi:10.1158/1538-7445.AM2015-CT225