Preliminary Safety and Efficacy of Rovalpituzumab Tesirine in Patients with Delta-Like Protein 3-Expressing Advanced Solid Tumors

Background: Delta-like protein 3 (DLL3) is an atypical Notch receptor family ligand expressed in high-grade neuroendocrine carcinomas (NECs), but not in normal tissue. Rovalpituzumab tesirine (Rova-T™) is an antibody-drug conjugate targeting DLL3. A Phase 1 study of Rova-T in small cell lung cancer showed encouraging antitumor activity in patients (pts) with DLL3 expression, and was well-tolerated1. Rova-T may also be active in other DLL3-expressing tumors. Methods: This is a Phase 1/2, open-label, multicenter study (NCT02709889) to determine safety and tolerability of Rova-T in 8 cohorts: malignant melanoma, medullary thyroid cancer (MTC), glioblastoma (GBM), large cell NEC (LCNEC), neuroendocrine prostate cancer (NEPC), high-grade gastroenteropancreatic NEC (GEP NEC), other NEC and other solid tumors. Eligible adults have a histologically confirmed, DLL3-expressing, advanced solid tumor relapsed/refractory to standard therapy, and no prior exposure to a pyrrolobenzodiazepine-based drug. A 3 + 3 dose escalation is used in each cohort, at doses 0.2-0.4 mg/kg of Rova-T administered intravenously on Day 1 of each 42-day cycle, and proceeding until a maximum tolerated dose (MTD) is determined. A 2-stage design will be used for disease-specific expansion cohorts. Results: As of 3 April 2017, 31 pts (2 melanoma, 2 MTC, 3 GBM, 3 LCNEC, 3 NEPC, 3 GEP NEC, 10 other NEC, 5 other solid tumor) have been treated (26 pts at 0.2 mg/kg, 5 pts at 0.3 mg/kg Rova-T). The MTD has not been reached. Twenty-six pts (84%) had an adverse event (AE), and only 3/31 pts (10%) had a Grade 3+ AE deemed to be related to Rova-T. Common AEs were fatigue (32%), nausea (29%), and constipation (23%). Four pts had serosal effusions, 2 (6%) of which were assessed to be drug-related, and 3 pts (10%) had adverse skin reactions. Ten pts (32%) discontinued treatment, 5 for progressive disease and 4 due to AEs. Eleven pts have had post-baseline tumor assessments, and anti-tumor activity has been observed in multiple disease cohorts. Conclusions: Preliminary safety and efficacy data of Rova-T warrant continued study in these disease populations, and will be updated at time of presentation. 1. Rudin et al., Lancet Oncol 2016. Clinical trial identification: NCT02709889 Legal entity responsible for the study: AbbVie Stemcentrx Funding: AbbVie Stemcentrx Disclosure: A. Mansfield: Consulting to Genentech, BMS and Trovagene with honoraria provided to institution. H. Beltran, K. Lewis: Research funding from AbbVie Stemcentrx. A.F. Farago: Consulting or advisory role for AbbVie, Pharmamar, Merrimack Pharmaceuticals, Takeda, Intervention Insights. Honorarium from Foundation Medicine. C.L. Hann: Advisory board for AbbVie Stemcentrx and BMS. Research funding from GlaxoSmithKline and Merrimack Pharmaceuticals. S. Richey: Employee of Texas Oncology. Consulting or advisory role for Exelixis, Pfizer, Prometheus and Sanofi. Research funding from Novartis, BMS, Eisai, Genentech/Roche, GSK, and AbbVie. D. Smith: Research funding from US Oncology. H.P. Soares: Advisory board for Cornerstone Pharmaceuticals. Research funding from Novartis. Consultant fees/honoraria for Ipsen. A. Spira: Consultant for AbbVie. Research funding from AbbVie (to institution). S. Lally, M. Rossi, L. Saunders, S.J. Dylla, E. Kavalerchik: Employee of AbbVie Stemcentrx and may own stock. L. Anthony: Research funding from AbbVie Stemcentrx, Lexicon Pharmaceuticals, Novartis, Markey Cancer Center Foundation. All other authors have declared no conflicts of interest.