Phase II trial of nivolumab and metformin in patients with treatment-refractory microsatellite stable metastatic colorectal cancer

Abstract

Background: Preclinical studies showed metformin reduces exhaustion of tumor-infiltrating lymphocytes and potentiates programmed cell death protein-1 (PD-1) blockade. We hypothesized that metformin with nivolumab would elicit potent antitumor and immune modulatory activity in metastatic microsatellite stable (MSS) colorectal cancer (CRC). We evaluated this hypothesis in a phase II study.

Methods: Nivolumab (480 mg) was administered intravenously every 4 weeks while metformin (1000 mg) was given orally, two times per day following a 14-day metformin only lead-in phase. Patients ≥18 years of age, with previously treated, stage IV MSS CRC, and Eastern Cooperative Oncology Group 0-1, having received no prior anti-PD-1 agent were eligible. The primary endpoint was overall response rate with secondary endpoints of overall survival (OS) and progression-free survival (PFS). Correlative studies using paired pretreatment/on-treatment biopsies and peripheral blood evaluated a series of immune biomarkers in the tumor microenvironment and systemic circulation using ChipCytometry and flow cytometry.

Results: A total of 24 patients were enrolled, 6 patients were replaced per protocol, 18 patients had evaluable disease. Of the 18 evaluable patients, 11/18 (61%) were women and the median age was 58 (IQR 50-67). Two patients had stable disease, but no patients had objective response, hence the study was stopped for futility. Median OS and PFS was 5.2 months (95% CI (3.2 to 11.7)) and 2.3 months (95% CI (1.7 to 2.3)). Most common grade 3/4 toxicities: Anemia (n=2), diarrhea (n=2), and fever (n=2). Metformin alone failed to increase the infiltration of T-cell subsets in the tumor, but combined metformin and nivolumab increased percentages of tumor-infiltrating leukocytes (p=0.031). Dual treatment also increased Tim3+ levels in patient tissues and decreased naïve CD8+T cells (p=0.0475).

Conclusions: Nivolumab and metformin were well tolerated in patients with MSS CRC but had no evidence of efficacy. Correlative studies did not reveal an appreciable degree of immune modulation from metformin alone, but showed trends in tumorous T-cell infiltration as a result of dual metformin and PD-1 blockade despite progression in a majority of patients.

Trial registration: ClinicalTrials.gov NCT03800602.

Keywords: Clinical Trials, Phase II as Topic; Drug Therapy, Combination; Immunotherapy; Translational Medical Research.

Figure 1

Clinical trial design. Patient biopsies were isolated from liver metastases prior to and immediately following either the first treatment cycle (metformin) or the second treatment cycle (metformin and nivolumab). They were stained with a panel of 13 markers centered around identifying immune cell populations. Peripheral blood samples were extracted prior to and following each treatment cycle. Flow cytometry was performed to analyze T cell and myeloid markers at different treatment time points. am, in the morning; BID, two times per day; CRC, colorectal cancer; D, day; IV, intravenous; MSS, microsatellite stable; pm, in the evening; q, every.

Figure 2

Consolidated Standards of Reporting Trials flow diagram.

Figure 3

(A and B) Median OS and PFS was 5.2 months (95% CI (3.2 to 8.4)) and 2.2 months (95% CI (1.7 to 2.3)) in intention-to-treat cohort. (C and D) Median OS and PFS was 5.2 months (95% CI (3.2 to 11.7)) and 2.3 months (95% CI (1.7 to 2.3)) in evaluable patients. OS, overall survival; PFS, progression-free survival.

Figure 4

Immune profiling of patient tissues. (A–B) Patient 004, metformin only. Right: pretreatment; Left: post-treatment. 13-plex marker staining suggests that metformin treatment increased the infiltration of T-cell subsets into patient tumor microenvironment. (C–D) Patient 013, metformin and nivolumab. Right: pretreatment; Left and bottom: post-treatment. 13-plex marker staining suggests that metformin and nivolumab combination treatment increased the infiltration of T-cell subsets into patient tissue tumor microenvironment, illustrating the immunomodulatory effect of this treatment on the tumor microenvironment of this individual patient (013). Arrows in orange indicate populations of interest that have increased post-treatment, mostly CD4⁺ and CD45RO⁺ populations.

Figure 5

Treatment-induced changes in immune profiles of metastatic colorectal tumors. 13-plex immunohistochemistry analysis revealed changes in immune cell phenotypes in pretreatment versus post-treatment liver biopsy tissue between cohorts of patients receiving a lead in with metformin (n=7) only versus metformin and nivolumab (n=6). Changes were identified in (A) lymphocytes, (B) percentages of effector CD4 T cells and (C) PDL1⁻Tim3⁺ cell populations. Each line represents matched pretreatment and post-treatment biopsies from the same patient. *p<0.05 via Wilcoxon signed-rank test.

Figure 6

Treatment-induced changes in peripheral blood immune cells of patients with metastatic colorectal cancer. (A) Representative gating scheme for phenotypic analysis of naïve CD3⁺ CD4⁺/8⁺ CD45RA+CCR7+ T cells, effector CD4⁺/8⁺ CD45RA+CCR7 T cells, central memory CD4⁺/8⁺ T CD45RA⁻ CCR7⁺ cells and effector memory CD4⁺/8⁺ CD45RA⁻ CCR7⁻ T cells (left figure shows the gating for CD8 and CD4 while the right figure shows the gating for CCR7 and CD45RA). (B) Changes in populations of effector CD3⁺ CD4⁺ CD45RA⁺ CCR7⁻ T cells from screening to C1D15 (n=17). (C) Changes in populations of naïve CD3⁺ CD8⁺ CD45RA⁺ CCR7⁺ T cells from screening to end of treatment (n=17). Each line represents matched peripheral blood samples from the same patient. *p<0.05 via Kruskal-Wallis statistical test.