A phase 2 study of GVAX colon vaccine with cyclophosphamide and pembrolizumab in patients with mismatch repair proficient advanced colorectal cancer

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Abstract

Background: Mismatch repair proficient (MMRp) colorectal cancer (CRC) has been refractory to single-agent programmed cell death protein 1 (PD1) inhibitor therapy. Colon GVAX is an allogeneic, whole-cell, granulocyte-macrophage colony-stimulating factor -secreting cellular immunotherapy that induces T-cell immunity against tumor-associated antigens and has previously been studied in combination with low-dose cyclophosphamide (Cy) to inhibit regulatory T cells. Methods: We conducted a single-arm study of GVAX/Cy in combination with the PD1 inhibitor pembrolizumab in patients with advanced MMRp CRC. Patients received pembrolizumab plus Cy on day 1, GVAX on day 2, of a 21-day cycle. The primary endpoint was the objective response rate by Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1. Secondary objectives included safety, overall survival, progression-free survival, changes in carcinoembryonic antigen (CEA) levels, and immune-related correlates. Results: Seventeen patients were enrolled. There were no objective responses, and the disease control rate was 18% by RECIST 1.1. The median progression-free survival was 82 days (95% confidence interval [CI], 48-97 days) and the median overall survival was 213 days (95% CI 179-441 days). Biochemical responses (≥30% decline in CEA) were observed in 7/17 (41%) of patients. Grade ≥ 3 treatment-related adverse events were observed in two patients (hemolytic anemia and corneal transplant rejection). Paired pre- and on-treatment biopsy specimens showed increases in programmed death-ligand 1 expression and tumor necrosis in a subset of patients. Conclusions: GVAX/Cy plus pembrolizumab failed to meet its primary objective in MMRp CRC. Biochemical responses were observed in a subset of patients and have not previously been observed with pembrolizumab monotherapy in MMRp CRC, indicating that GVAX may modulate the antitumor immune response.

Original languageEnglish (US)
Pages (from-to)1485-1494
Number of pages10
JournalCancer medicine
Volume9
Issue number4
DOIs
StatePublished - Feb 1 2020

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Keywords

  • PD-1
  • checkpoint inhibitor
  • colorectal cancer
  • immunotherapy
  • vaccine

ASJC Scopus subject areas

  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Cancer Research

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