Viagenpumatucel-L Bolsters Response to Nivolumab Therapy in Advanced Lung Adenocarcinoma: Preliminary Data from the DURGA Trial

Viagenpumatucel-L (HS-110) is an allogeneic whole-cell vaccine, selected for high expression of adenocarcinoma tumor antigens, transfected to secrete gp96-Ig. Prior studies with HS-110 (and related gp96-Ig vaccines) have shown a correlation between increases in CD8+ tumor infiltrating lymphocytes (TIL) and tumor response. The DURGA trial was designed evaluate the combination of HS-110 and nivolumab, in an attempt to increase tumor inflammation and improve the response rates observed with nivolumab alone. Clinical Trial identifier: NCT02439450. Patients with advanced lung adenocarcinoma who received at least one prior line of therapy were assigned to two cohorts based on baseline levels of TIL in patient biopsies: low TIL (≤10% CD8+ T cells) or high TIL (>10% CD8+ T cells). All patients received standard of care nivolumab 3 mg/kg every 2 weeks and weekly HS-110 for 18 weeks until intolerable adverse events, disease progression, or death. Each 9-patient Phase 1b cohort could be expanded to 30 patients in Phase 2 based on exhibited efficacy. The primary endpoint was safety and tolerability. Biopsies at baseline and Week 10 were used to track changes in TIL and PD-L1 staining. Peripheral blood mononuclear cells (PBMC) were evaluated by flow cytometry for detection of circulating leukocyte subsets. ELISPOT was used to track antigen-specific immune response. HS-110 vaccine and nivolumab combination was well tolerated with a safety profile consistent with single-agent nivolumab. Among the 8 initial patients, only 4 had optimal biopsies which showed 2 patients with high and 2 with low TILs. PD-L1 was >1% in 3 patients. IFNγ ELISPOT assay defined 4 patients as immune responders (doubling of IFNγ-secreting cells after re-stimulation with total vaccine antigen and individual cancer antigens, IR) and 4 patients as non-immune responders (NIR). The overall response rate (ORR) was 50% in the IR patients and 0% in the NIR patients. At the time of the data cutoff, 6 patients remain alive, including the 4 IR patients, with ongoing responses for 150 to 326 days. Patients with objective response also exhibited injection site reactions and maculopapular rash consistent with HS-110 mechanism of action, decreased Myeloid Derived Suppressor Cells (MDSC) in the blood, and increased markers of activated CD8+ T cell subsets by flow cytometry (CD8+CTLA-4+, CD8+Tim3+). Although the pathology specimens were sub-optimal in the two responding patients, the limited tissue available showed lower baseline TILs in both patients. Allogeneic gp96-based vaccination may have synergistic activity in combination with immune checkpoint inhibitors.