Galinpepimut-S in Combination With Pembrolizumab in Patients With Selected Advanced Cancers

This is a Phase 1/2, open-label, non-comparative, multicenter, multi-arm (basket-type) study of galinpepimut-S (a multivalent WT1 analog peptide vaccine) in combination with the programmed death-1 (PD1) inhibitor pembrolizumab, in patients with metastatic colorectal cancer (mCRC), metastatic ovarian cancer (mOvC), advanced small-cell lung cancer (SCLC), triple-negative breast cancer (TNBC), and acute myeloid leukemia (AML).

Additional details of tumors and prior therapies: mCRC treated with at least two prior lines, mOvC treated with at least one prior line, SCLC treated with one prior line, TNBC treated with at least one prior line, and AML unable to attain a morphological partial response after hypomethylating agents and who are not eligible for allogeneic hematopoietic stem cell transplant.

The primary objectives of the study are to assess the safety, tolerability, and anti-tumor activity of galinpepimut-S in combination with pembrolizumab. The secondary and exploratory objectives include duration of response, overall survival, and progression-free survival.

The study will enroll approximately 90 patients at up to 20 centers in the United States.

The first two galinpepimut-S injections will initially be administered as monotherapy every three weeks (Week 0 and Week 3). Thereafter, galinpepimut-S will be co-administered with pembrolizumab every three weeks for four additional administrations (for the galinpepimut-S initial immunization induction phase series; weeks 6-15) to coincide with the per label pembrolizumab dosing frequency. After that, there will be one un-paired administration of pembrolizumab (week 18), and then galinpepimut-S will be resumed Q3W for six additional doses (early immune booster phase; weeks 21-36).

At the end of this phase, there will be a 12-week interval where three unpaired administrations of pembrolizumab will occur (weeks 39-45), and then galinpepimut-S will be resumed on an every 12-week schedule for four additional doses (late immune booster phase; weeks 48-84). After 84 weeks, continuing non-progressed patients will be treated with pembrolizumab alone up until week 111.

Pembrolizumab will be administered at a dose of 200 mg intravenously Q3W on Day 1 of each cycle (three week cycles) starting on Study Week 6 and continuing for up to two years thereafter (Study Week 111). Galinpepimut-S will be administered 30-60 minutes after the completion of IV infusion of pembrolizumab on Day 1 of each cycle during which the two drugs are being co-administered.