An open-label study of rovalpituzumab tesirine in patients with DLL3-expressing advanced solid tumors.

Abstract

TPS2597 Background: Delta-like protein 3 (DLL3) is an inhibitory ligand of the Notch receptor family. It is highly expressed in high-grade neuroendocrine carcinoma (NEC), such as small cell lung cancer (SCLC) and large cell NEC (LCNEC), but is not expressed in normal tissue. DLL3 is expressed in melanoma, glioblastoma (GBM), neuroendocrine prostate, medullary thyroid carcinoma (MTC), and other solid cancers. Rovalpituzumab tesirine (Rova-T™) is an antibody-drug conjugate targeting DLL3, composed of a DLL3-specific IgG1 monoclonal antibody joined to a toxic DNA cross-linking agent by a cleavable linker. Rova-T binds to DLL3 on target-expressing cells, is internalized and cleaved, releasing the toxin to induce cell death. A Phase 1 study of Rova-T in SCLC showed encouraging antitumor activity in DLL3-high patients (pts), and was well-tolerated (Rudin et al., Lancet Oncol, 2016). As novel therapies are needed for multiple cancers that express DLL3, Rova-T may be effective in these tumors. Methods: This is a Phase 1/2, open-label, multicenter study (NCT02709889) with 8 cohorts of pts (up to ~318 total, 14 pts enrolled as of 20 January 2017) with melanoma, MTC, GBM, LCNEC, neuroendocrine prostate cancer, gastroenteropancreatic NEC, other NEC, or other solid tumor. In Part A, a 3+3 dose escalation will be used. Rova-T 0.2, 0.3, or 0.4 mg/kg will be given on Day 1 of each 42-day cycle. Dose-limiting toxicities (DLTs) will be assessed over a 21-day period. Dose escalation will proceed within cohort until a maximum tolerated dose is reached. Part B expansion, Stage 1, will explore the recommended dose in 7 pts in disease specific cohorts. Stage 2 will use an adaptive 2-stage design to determine sample size. Pt eligibility: ≥ 18 years; histologically confirmed, measurable, advanced solid tumor; relapsed/refractory to prior standard therapy; ECOG 0-1; no prior exposure to a pyrrolobenzodiazepine-based drug. Primary objective: assess safety and tolerability of Rova-T. Secondary objectives: explore Rova-T antitumor activity, pharmacokinetics, and incidence of anti-therapeutic antibodies. Exploratory objectives: explore the relationship between DLL3 and clinical outcome, and effects on biomarkers and pharmacodynamics. Clinical trial information: NCT02709889.