Abstract 3781
Background
SD-101 is a synthetic CpG-ODN agonist of TLR9. Pembrolizumab is an antibody to PD-1. DV3-MEL-01 (SYNERGY-001) assesses the safety and preliminary efficacy of the combination of SD-101 and pembrolizumab in stage IIIC-IV melanoma.
Methods
Phase 1b evaluated SD-101 at multiple doses injected in a single tumor Q1W x 4 then Q3W x 7 in combination with a fixed dose of pembrolizumab (200 mg IV Q3W). Phase 2 is evaluating SD-101 at 8 mg in 1 lesion and 2 mg/lesion in 1-4 lesions. Patients were eligible if their tumor progressed on or after prior anti-PD-1 therapy. Scans are performed every 64 days. Per-protocol overall responses (ORR) were assessed per investigator using RECIST v1.1/irRECIST. The modified intent-to-treat (mITT) population included all patients except those on study who had not reached the Day 64 scan. PFS rate was calculated using the mITT population. The per-protocol population comprised patients who received at least 1 dose of each drug and had ≥1 post baseline scan.
Results
38 patients enrolled: median age 64 years; male 74%; ECOG PS 0 58%; Stage IIIC 32%, IVM1a/b 13%, Stage IVM1c/d 50%; LDH > ULN 39%. SD-101 safety profile consists of transient, mild-to-moderate flu-like symptoms and injection-site reactions. Grade 3-4 treatment-related AEs = 32%. Immune-related AEs (irAEs) = 5%. ORR (mITT) = 16% (6/37) (CR 3%/PR 14%/SD 30% [DCR = 46%]/PD 38%/NE 16%). Evaluable ORR =19% (6/31). 7 pts were not evaluable: on study but no Day 64 scan yet (n = 1), AE (n = 1), clinical PD (n = 2), withdrew consent/unknown (n = 3). 2 of 8 patients who began combination therapy within 3 months of starting anti-PD-1 therapy had responses including 1 CR. Median DOR not reached (range 9 weeks, 45 weeks). Median follow up = 13 weeks (range 6, 45 weeks). 6 month PFS rate = 16%. One third of the patients currently have biomarker assessments demonstrating a broad increase in TILs in patients with responses with ≥ 3 fold increase in T cells.
Conclusions
The combination of SD-101 and pembrolizumab induced responses in some patients who developed progressive disease on or after prior anti-PD-1 therapy. The combination is well tolerated with no evidence of an increased rate of irAEs.
Clinical trial identification
NCT02521870.
Legal entity responsible for the study
Dynavax Technologies Corporation.
Funding
Dynavax Technologies Corporation.
Editorial Acknowledgement
Disclosure
A. Ribas: Consulting fees: Dynavax Technologies. C. Lao: Research funding: Merck. A. Amin: Honoraria, Speaker’s bureau: Merck & Co. M. Milhem: Advisory board: Blueprint Medicines GIST. S. Chandra: Membership on advisory boards and/or Speaker's Bureau Member: EMD Serono, Bristol-Myers Squibb, Array BioPharma, Regeneron. E.V. Schmidt: Employee: Merck. R. Janssen: Employee: Dynavax Technologies Corporation; Shareholder: Dynavax and Merck stock. All other authors have declared no conflicts of interest.