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-g producing TEM-RAs 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.

Purpose: Chemotherapy has long been the standard treatment for advanced stage non-small cell lung cancer (NSCLC), but checkpoint inhibitors are now approved for use in several patient groups and combinations. To design optimal combination strategies, a better understanding of the immunemodulatory capacities of conventional treatments is needed. Therefore, we investigated the immune-modulatory effects of paclitaxel/carboplatin/bevacizumab (PCB), focusing on the immune populations associated with the response to checkpoint inhibitors in peripheral blood.Experimental Design: A total of 223 patients with stage IV NSCLC, enrolled in the NVALT12 study, received PCB, with or without nitroglycerin patch. Peripheral blood was collected at baseline and after the first and second treatment cycle, proportions of T cells, B cells, and monocytes were determined by flow cytometry. Furthermore, several subsets of T cells and the expression of Ki67 and coinhibitory receptors on these subsets were determined.Results: Although proliferation of CD4 T cells remained stable following treatment, proliferation of peripheral blood CD8 T cells was significantly increased, particularly in the effector memory and CD45RA þ effector subsets. The proliferating CD8 T cells more highly expressed programmed death receptor (PD)-1 and cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) compared with nonproliferating CD8 T cells. Immunologic responders (iR; >2 fold increased proliferation after treatment) did not show an improved progression-free (PFS) or overall survival (OS).Conclusions: Paclitaxel/carboplatin/bevacizumab induces proliferation of CD8 T cells, consisting of effector cells expressing coinhibitory checkpoint molecules. Induction of proliferation was not correlated to clinical outcome in the current clinical setting. Our findings provide a rationale for combining PCB with checkpoint inhibition in lung cancer.

Background: We assessed the clinical validity of circulating tumor cell (CTC) quantification for prognostication of patients with advanced non-small cell lung cancer (NSCLC) by undertaking a European pooled analysis of individual patient data. This is the largest study of its kind and the first to examine between-centre heterogeneity of CTC identification in NSCLC. Methods: Nine European NSCLC CTC centers were asked to provide reported/unreported anonymised data for patients with advanced NSCLC who participated in CellSearch CTC studies from January 2003 -March 2017. We used Cox regression models, stratified by centre, to establish the association between CTC count and survival. We assessed the added value of CTCs to prognostic clinico-pathological models using likelihood ratio (LR) statistics and c-indices. Results: Seven out of nine eligible centers provided data for 550 eligible patients, including 209 patients whose prognostic information was previously unpublished. CTC counts of ! 2 and !5 per 7Á5 mL were associated with reduced progression-free survival (!2 CTCs: HR 1.72, p < 0Á001; !5 CTCs: HR 2.21, p < 0Á001) and overall survival (!2 CTCs: HR 2Á18, p < 0Á001; !5 CTCs: HR 2Á75, p < 0Á001), respectively. Survival prediction was significantly improved by addition of baseline CTC count to LR clinico-pathological models (log-transformed CTCs p < 0Á0001; !2 CTCs p < 0Á0001; !5 CTCs p < 0Á0001), while more moderate improvements were observed with the use of c-index models. There was minor evidence of between-center heterogeneity in the effect on PFS, but not OS.No difference in CTC profile was observed between key NSCLC molecular subsets such as EGFR, ALK, and KRAS. Conclusions: These data confirm CTCs as an independent prognostic indicator of progression-free survival and overall survival in advanced NSCLC. CTC count improves prognostication when added to full clinico-pathological predictive models. !2 CTCs is an appropriate cutoff to move towards establishing clinical utility.

No abstract