Notch pathway inhibition with LY3039478 in adenoid cystic carcinoma (ACC).

Abstract

6024 Background: ACCs have high levels of Notch-1 receptor expression and activation. LY3039478 (LY) is an orally bioavailable selective Notch inhibitor (Notch 1-4). Here we report on safety, pharmacokinetics (PK), pharmacodynamics (PD), and anti-tumor activity of LY in patients (pts) with ACC. Methods: Ongoing, multi-part, phase I trial enrolled pts with advanced or metastatic ACC, measurable disease, ECOG ≤1, and baseline tumor tissue. Eligible pts received LY 50 mg three times per week (TIW), on a 28-day cycle until disease progression. Safety assessments were based on CTCAE V4.0. Tumor responses were assessed using RECIST 1.1. Primary objectives are to confirm the recommended phase II dose of LY and document antitumor activity. Secondary objectives are safety and toxicity, PK and progression-free survival (PFS). Exploratory objectives include assessment for PET metabolic responses. Results: 22 pts have been enrolled and received LY 50mg TIW (13 men, 9 women; median age 60, range 41-82). All pts had metastatic disease; median treatment duration was 3 cycles (range 1-10) with 6 pts continuing on treatment. One pt had an unconfirmed partial response. Disease control rate (DCR) was 16/22 (73%), of which 4 pts had stable disease ≥ 6 months. In the overall group (n = 22) median PFS (mPFS) was 5.3 months (95% CI: 2.4, NE). mPFS was 7.7 (95% CI: 4.0, NE) for pts in second line (n = 7), while mPFS was 2.4 (95% CI: 1.1, NE) for pts in third line or more (n = 9). In pts without prior systemic therapy (n = 6) mPFS could not be estimated since 4 of those patients were censored. In preliminary analysis, 14 pts were assessed by PET, with 2 (14%) achieving partial metabolic response. Most frequent related adverse events (all grades) occurring in ≥20% of pts included diarrhea (55%), fatigue (45%), vomiting (36%), decreased appetite (27%), dry mouth (27%), and dry skin (23%). Grade 3/4 related treatment-emergent adverse events observed in more than one pt were diarrhea (n = 3) and squamous cell carcinoma of skin (n = 2). PK was assessed in 17 pts, with peak concentrations occurring approximately 2 hours post-dose. Biomarker and histologic analyses of pre and post treatment biopsies will be presented. Conclusions: LY showed activity (73% DCR) in ACC with a manageable safety profile. Clinical trial information: NCT01695005.