Nivolumab and Relatlimab for the Treatment of Patients with Unresectable or Metastatic Mismatch Repair-Proficient Colorectal Cancer

Abstract

Purpose: Combined inhibition of lymphocyte-activation gene 3 (LAG-3) and PD-1 improves outcomes in patients with melanoma. Increased LAG-3 expression in colorectal cancer correlates with reduced survival. Higher mucin and PD-L1 expression in the mismatch repair-proficient (pMMR) colorectal cancer tumor microenvironment was associated with increased LAG-3 and retrospectively with prolonged progression-free survival upon PD-1 blockade. This led to the hypothesis that LAG-3/PD-1 inhibition would improve clinical outcomes in this pMMR colorectal cancer subset.

Patients and methods: NCT03642067 was a phase II study evaluating the combination of relatlimab (LAG-3 inhibitor) and nivolumab (PD-1 inhibitor) in patients with previously treated metastatic pMMR colorectal cancer. Patients were enrolled into one of three cohorts: A, mucin/PD-L1-high; B, mucin/PD-L1-low; or C, mucin/PD-L1 unselected. The primary endpoint for each cohort was the objective response rate.

Results: We enrolled 59 evaluable patients; best treatment responses were partial response (3), stable disease (6), and progressive disease (50). Response rates did not differ significantly between cohorts. Subgroup analyses demonstrated that two of five patients with lung-only metastases had a partial response. Comparison of liver and lung metastases identified higher baseline dendritic cell densities in lung lesions. Nivolumab/relatlimab resulted in increased intratumoral cytotoxic T cells. Lower baseline intratumoral regulatory T cells and ADAM10+ cancer cells correlated with clinical response.

Conclusions: This investigation did not reach its primary endpoint for any of the three treatment cohorts but does provide critical insight into the effects of combining nivolumab/relatlimab on the colorectal cancer tumor microenvironment and identifies subgroups that may derive greater benefit from this combination.

Figure 1.. Kaplan-Meier curves for progression-free and overall survival in microsatellite stable colorectal cancer patients treated with relatlimab and nivolumab.

Following administration of relatlimab and nivolumab per protocol, patients were followed for survival outcomes measured as time from cycle 1 day 1 of treatment to (A) disease progression on radiographic imaging or (B) death respectively. At the time of data censoring, no patients were still on active treatment and 6 were still alive.

Figure 2.. Evaluation of metastatic site-specific responses to nivolumab and relatlimab.

To understand the influence that location of metastases had on outcomes for patients with pMMR CRC treated with nivolumab and relatlimab, survival outcomes as a function of whether the patient had active liver metastases at the time of study enrollment was evaluated. We took the group without liver metastases and also looked individually at the patients with lung-only metastases. Progression-free survival (A) and overall survival (B) were compared between patients with these different sites of metastasis. A “site specific” RECIST was calculated for liver and the other sites independently for patients with liver and lung (C), liver and peritoneum (D), and liver and other sites (E) to assess whether tumors in different locations responded differently to nivolumab/relatlimab within the same patient.

Figure 3.. Circulating immune cell changes following relatlimab (anti-LAG-3) and nivolumab (anti-PD-1) treatment in pMMR CRC.

To determine the circulating immune cell changes with relatlimab and nivolumab treatment we performed mass cytometry consisting of a panel of markers to identify immune cell populations, their subsets, and the expression of different activation and exhaustion markers on peripheral blood mononuclear cells obtained prior to cycle 1 day 1 (PreTx) and after 4 weeks of treatment (OnTx). Boxplots showing proportions of (A) naïve T cell subsets and (B) NK and B cells in responders (R) and nonresponders (NR; stable and progressive disease). (C) Line plots show proportions of effector memory T cells and regulatory T cells at PreTx and OnTx timepoints for each patient. Expression of (D) costimulatory/activation markers, (E) CD25, and (F) coinhibitory/exhaustion markers by helper T cell subsets are also shown as line plots. Non-responders (NR) and Responders (R) are indicated by red solid and dotted blue lines, respectively. Each shape represents a unique patient. All data are representative of 15 paired patient samples. P-values are calculated by paired t-tests. Abbreviations: Acv, activated; CM, central memory; EM, effector memory; Ex, exhausted; Tc, cytotoxic T cells; Th, helper T cells.

Figure 4.. TME correlates of relatlimab/nivolumab.

(A) Representative IMC results for two multicolored sets of phenotyping markers are shown in six distinct regions. Scale bar: 200µm. (B) Detailed expression profiles for epithelial/cancer cell clusters are shown as scaled heatmap. (C) Proportions of cell types are shown as boxplots stratified by pre- (PreTx, n=57) vs. on-treatment (OnTx, n=38) timepoints. (D) Proportions of cell types at only baseline timepoint are compared between representative regions analyzed by IMC from non-responders (NR; stable and progressive disease, n=49) and responders (R; partial response, n=8). P-values are calculated by unpaired t-tests.

Figure 5.. Distance relationships among cell types in the TME of non-responders and responders.

(A) Average shortest distances between every cell type were calculated and plotted as networks. The size of the node indicates the abundance of the cluster and the thickness of the line along with the relative proximity correlates with distance. Dashed regions highlight spatial associations among T cell subtypes. (B) Distances from memory CD45RO⁺CD8⁺ T cells (TcM), memory CD45RO⁺CD4⁺ T cells (ThM), and helper T cell (Th) to Tregs for non-responders and responders are shown as violin plots. P-values are calculated by unpaired t-tests.