Efficacy of nivolumab and ipilimumab in patients with malignant pleural mesothelioma is related to a subtype of effector memory cytotoxic T cells: Translational evidence from two clinical trials

Abstract

Background: Combined immune checkpoint inhibitor (ICI) treatment targeting PD-1 and CTLA-4 was suggested to yield clinical benefit over chemotherapy in malignant pleural mesothelioma (MPM), whereas aPD-1 monotherapy failed to provide benefit in phase-III trials. Success of ICI depends on the presence and activation of tumor-specific T cells. Therefore, we investigated whether T-cell characteristics are underlying clinical efficacy of ICI treatment in MPM.

Methods: Comprehensive immune cell profiling was performed on screening and on treatment peripheral blood samples of mesothelioma patients treated with nivolumab (aPD-1) monotherapy (NCT02497508), or a combination of nivolumab and ipilimumab (aCTLA-4) (NCT03048474).

Findings: aPD-1/aCTLA-4 combination treatment induced a profound increase in proliferation and activation of T cells, which was not observed upon aPD-1 monotherapy. Moreover, patients that responded to combination treatment had low frequencies of naive CD8 T cells and high frequencies of effector memory CD8 T cells that re-expressed RA (TEMRA) at screening. The frequency of Granzyme-B and Interferon-γ producing TEMRAs was also higher in responding patients.

Interpretation: High proportions of TEMRAs and cytokine production by TEMRAs before treatment, was associated with a better clinical outcome. TEMRAs, which likely comprise tumor-specific T cells, tend to require blockage of both aPD-1 and aCTLA-4 to be reactivated. In conclusion, peripheral blood TEMRAs can play a key role in explaining and predicting clinical benefit upon aPD-1/aCTLA-4 combination treatment.

Funding: Bristol-Myers Squibb sponsored NivoMes and INITIATE clinical trials and provided study drugs. No external funding was applicable for the flow cytometric analyses of peripheral blood samples described in this manuscript.

Keywords: Immune checkpoint inhibitors; Immune monitoring; Immunotherapy; Ipilimumab; Malignant pleural mesothelioma; Nivolumab.

Conflict of interest statement

Declaration of Competing Interest Prof. dr. Aerts reports personal fees from Eli Lilly, Roche, Boehringer Ingelheim, BMS, MSD, Amphera and AstraZeneca. Furthermore, prof. dr. Aerts has a patent pending on tumour lysate antigen (EP2938354A1) and is stock owner at Amphera B.V. Immunotherapy. Prof. dr. Baas reports grants from BMS, during the conduct of this study. Furthermore, he receives grants from MSD, outside the submitted work. All other authors do not have any financial relationships to disclose.

Copyright © 2020. Published by Elsevier B.V.

Figures

Fig. 1

T- and NK-cell characteristics before and during aPD-1 monotherapy (a, c, d, f, h) Gating strategy for NK-cells (a), T-cells (c), CD4 T-cells subsets (d), CD8 T-cells subsets (f) and Treg subsets (h) respectively. (b, e, g, i) Percentage of T-and NK-cell subsets (b), CD4 T-cell subsets (e), CD8 T-cells subsets (g) and Treg subsets (I) respectively, at screening and on-treatment time points. (j, k, l) Percentage of Ki67+ CD 4 T-cell subsets (j), Tregs subsets (k) and CD8 T-cell subsets (l) respectively, at screening and on-treatment time points. (m, n, o). Paired samples are shown connected by black lines. Percentage of CD4 T-cell subsets (m), Treg subsets (n) and CD8 T-cell subsets (o) respectively, at the screening time point in responding and non-responding patients. Bars depict mean values with standard error of the mean.

Fig. 2

T- and NK-cell characteristics before and during aPD-1/CTLA-4 combination therapy (a, b, c, d) Percentage of T-and NK-cell subsets (a), CD4 T-cell subsets (b), Treg subsets (c) and CD8 T-cells subsets (d) respectively, at screening and on-treatment time points. (e, f, g) Percentage of Ki67+ CD 4 T-cell subsets, (TCM p = 0.003, TEM p = 0.007, TEMRA p = 0.028) (e), Tregs subsets (f) and CD8 T-cell subsets (TN p = 0.036, TCM p = 0.03,) (g) respectively, at screening and on-treatment time points. (h, i, j) Comparison between responding (R) and non-responding (NR) patients for the percentage of Ki67+ CD 4 T-cell subsets (TCM R p = 0.01, TCM NR p = 0.04, TEM R p = 0.01) (h), Tregs subsets (i) and CD8 T-cell subsets (j) respectively, at screening and on-treatment time points. Paired samples are shown connected by black lines in each graph. Significance (Wilcoxon signed-rank test for paired analysis of screening and on-treatment samples and Mann–Whitney U test for comparison of response groups) is shown in each graph, with * p < 0.05 and ** p < 0.01. P values were corrected for multiple testing, using the Benjamini and Hochberg False Discovery Rate.

Fig. 3

Percentage of ICOS+ T cell subsets before and during aPD-1/CTLA-4 combination therapy (a, b, c) Percentage of ICOS+ CD 4 T-cell subsets (TCM p = 0.002, TEM p = 0.003, TEMRA p = 0.004) (a), Tregs subsets (b) and CD8 T-cell subsets (TCM p =  0.003, TEM p = 0.012) (c) respectively, at screening and on-treatment time points. (d, e, f) Comparison between responding (R) and non-responding (NR) patients for the percentage of ICOS+ CD 4 T-cell subsets (TN NR p = 0.01, TCM NR p = 0.02, TEM NR p = 0.03, TEMRA NR p = 0.01 (d), Tregs subsets (nTreg NR p = 0.01) (e) and CD8 T-cell subsets (TCM R p = 0.03) (f) respectively, at screening and on-treatment time points. Paired samples are shown connected by black lines in each graph. Significance (Wilcoxon signed-rank test) is shown in each graph, with * p < 0.05 and ** p < 0.01. P values were corrected for multiple testing, using the Benjamini and Hochberg False Discovery Rate

Fig. 4

Comparison of T-cell characteristics before aPD-1/CTLA-4 combination therapy in responding and non-responding patients (a, b, c) Percentage of CD4 T-cell subsets (a), Treg subsets (b) and CD8 T-cell subsets (TN p = 0.017, TCM p = 0.008, TEMRA p = 0.028) (c) respectively, at the screening time point in responding and non-responding patients. Bars depict mean values with standard error of the mean. Significance (Mann–Whitney U test) is shown in each graph, with * p < 0.05 and ** p < 0.01. P values were corrected for multiple testing, using the Benjamini and Hochberg False Discovery Rate. (d, e) EMRA CD8 T-cells proportions prior to treatment were used to stratify progression-free survival (PFS) (d) and overall survival (OS) (e). Median proportion of EMRA CD8 T cells was used as a cut off between the ‘high’ vs ‘low’ group. Statistical significance of the difference between the two Kaplan–Meier curves was tested by log rank test with p = 0.045 for PFS (median PFS of 3.5 vs 13.1 months) and p = 0.086 for OS (median OS of 10.2 vs 25.9 months).

Fig. 5

Comparison of cytokine frequencies in CD8 T-cell subsets before aPD-1/CTLA-4 combination therapy in responding and non-responding patients (a, b) Percentage of IFNγ+ CD8 T-cell subsets (TEM p = 0.008, TEMRA p = 0.006) (a) and Granzyme-B+ CD8 T-cell subsets (TN p = 0.02, TCM p = 0.032, TEMRA p = 0.02) (b) respectively, at the screening time point in responding and non-responding patients. Bars depict mean values with standard error of the mean. Significance (Mann–Whitney U test) is shown in each graph, with * p < 0.05 and ** p < 0.01. P values were corrected for multiple testing, using the Benjamini and Hochberg False Discovery Rate. (c, d) Proportions of Granzyme-B+ EMRA CD8 T-cells prior to treatment were used to stratify progression-free survival (PFS) (d) and overall survival (OS) (e). Median proportion of Granzyme-B+ EMRA CD 8 T cells was used as a cut off between the ‘high’ vs ‘low’ group. Statistical significance of the difference between the two Kaplan–Meier curves was tested by log rank test with p = 0.14 for PFS (not significant, median PFS of 3.5 vs 10.8 months) and p = 0.051 for OS (not significant, median OS of 10.2 vs 32.6 months).