Dendritic cells loaded with allogeneic tumour cell lysate plus best supportive care versus best supportive care alone in patients with pleural mesothelioma as maintenance therapy after chemotherapy (DENIM): a multicentre, open-label, randomised, phase 2/3 study.

BACKGROUND: Dendritic cell immunotherapy has proven to be safe and induces an immune response in humans. We aimed to establish the efficacy of dendritic cells loaded with allogeneic tumour cell lysate (MesoPher, Amphera BV, 's-Hertogenbosch, Netherlands) as maintenance therapy in patients with pleural mesothelioma. METHODS: In this open-label, randomised, phase 2/3 study, patients with histologically confirmed unresectable pleural mesothelioma, aged 18 years or older, with an Eastern Cooperative Oncology Group performance status score of 0-1, and non-progressing disease after four to six cycles of standard chemotherapy (with pemetrexed 500 mg/m2 plus platinum [cisplatin 75 mg/m2 or carboplatin area under the curve of 5]) were recruited from four centres in Belgium, France, and The Netherlands. Participants were randomly assigned (1:1), using block randomisation (block size of 4), stratified by centre and histology (epithelioid vs other), to MesoPher treatment plus best supportive care or best supportive care alone. Patients received up to a maximum of five MesoPher infusions, with treatment administered on days 1, 15, and 29, and weeks 18 and 30. At each timepoint, participants received an injection of 25 × 106 dendritic cells (two-thirds of the dendritic cells were administered intravenously and a third were injected intradermally). Best supportive care was per local institutional standards. The primary endpoint was overall survival, assessed in all participants randomly assigned to treatment (full analysis set) and safety assessed in all randomly assigned participants, and who underwent leukapheresis if they were in the MesoPher group. This study is registered with ClinicalTrials.gov, NCT03610360, and is closed for accrual. FINDINGS: Between June 21, 2018, and June 10, 2021, 176 patients were screened and randomly assigned to the MesoPher group (n=88) or best supportive care alone group (n=88). One participant in the MesoPher group did not undergo leukapheresis. Mean age was 68 years (SD 8), 149 (85%) of 176 were male, 27 (15%) were female, 173 (98%) were White, two were Asian (1%), and one (1%) was other race. As of data cutoff (June 24, 2023), after a median follow up of 15·1 months (IQR 9·5-22·4), median overall survival was 16·8 months (95% CI 12·4-20·3; 61 [69%] of 88 died) in the MesoPher group and 18·3 months (14·3-21·9; 59 [67%] of 88 died) in the best supportive care group (hazard ratio 1·10 [95% CI 0·77-1·57]; log-rank p=0·62). The most common grade 3-4 treatment-emergent adverse events were chest pain (three [3%] of 87 in the MesoPher group vs two [2%] of 88 in the best supportive care group), dyspnoea (none vs two [2%]), anaemia (two [2%] vs none), nausea (none vs two [2%]), and pneumonia (none vs two [2%]). No deaths due to treatment-emergent adverse events were recorded. Treatment-related adverse events consisted of infusion-related reactions (fever, chills, and fatigue), which occurred in 64 (74%) of 87 patients in the MesoPher group, and injection-site reactions (itch, erythema, and induration), which occurred in 73 (84%) patients, and all were grade 1-2 in severity. No deaths were determined to be treatment related. INTERPRETATION: MesoPher did not show improvement in overall survival in patients with pleural mesothelioma. Immune checkpoint therapy is now standard of care in pleural mesothelioma. Further randomised studies are needed of combinations of MesoPher and immune checkpoint therapy, which might increase efficacy without adding major toxicities. FUNDING: Amphera BV and EU HORIZON.

Incidence, treatment and survival of malignant pleural and peritoneal mesothelioma: a population-based study.

INTRODUCTION: Malignant mesothelioma (MM) is an aggressive cancer that primarily arises from the pleura (MPM) or peritoneum (MPeM), mostly due to asbestos exposure. This study reviewed the Dutch population-based incidence, treatment and survival since the national ban on asbestos in 1993. MATERIALS AND METHODS: Patients with MPM or MPeM diagnosed from 1993 to 2018 were selected from the Dutch cancer registry. Annual percentage change (APC) was calculated for (age-specific and sex-specific) revised European standardised incidence rates (RESR). Treatment pattern and Kaplan-Meier overall survival analyses were performed. RESULTS: In total, 12 168 patients were included in the study. For male patients younger than 80 years, the MM incidence significantly decreased in the last decade (APC ranging between -9.4% and -1.8%, p<0.01). Among both male and female patients aged over 80 years, the incidence significantly increased during the entire study period (APC 3.3% and 4.6%, respectively, p<0.01). From 2003 onwards, the use of systemic chemotherapy increased especially for MPM (from 9.3% to 39.4%). Overall, 62.2% of patients received no antitumour treatment. The most common reasons for not undergoing antitumour treatment were patient preference (42%) and performance status (25.6%). The median overall survival improved from 7.3 (1993-2003) to 8.9 (2004-2011) and 9.3 months from 2012 to 2018 (p<0.001). CONCLUSION: The peak of MM incidence was reached around 2010 in the Netherlands, and currently the incidence is declining in most age groups. The use of systemic chemotherapy increased from 2003, which likely resulted in improved overall survival over time. The majority of patients do not receive treatment though and prognosis is still poor.

OX40 agonism enhances PD-L1 checkpoint blockade by shifting the cytotoxic T cell differentiation spectrum.

Immune checkpoint therapy (ICT) has the power to eradicate cancer, but the mechanisms that determine effective therapy-induced immune responses are not fully understood. Here, using high-dimensional single-cell profiling, we interrogate whether the landscape of T cell states in the peripheral blood predict responses to combinatorial targeting of the OX40 costimulatory and PD-1 inhibitory pathways. Single-cell RNA sequencing and mass cytometry expose systemic and dynamic activation states of therapy-responsive CD4+ and CD8+ T cells in tumor-bearing mice with expression of distinct natural killer (NK) cell receptors, granzymes, and chemokines/chemokine receptors. Moreover, similar NK cell receptor-expressing CD8+ T cells are also detected in the blood of immunotherapy-responsive cancer patients. Targeting the NK cell and chemokine receptors in tumor-bearing mice shows the functional importance of these receptors for therapy-induced anti-tumor immunity. These findings provide a better understanding of ICT and highlight the use and targeting of dynamic biomarkers on T cells to improve cancer immunotherapy.

High-intensity statins are associated with improved clinical activity of PD-1 inhibitors in malignant pleural mesothelioma and advanced non-small cell lung cancer patients.

BACKGROUND: In preclinical models, statins showed vaccine adjuvant activities and synergized with PD-1 inhibitors. We analyzed the impact of statin treatment on clinical outcome in thoracic cancer patients treated with PD-1 inhibitors. METHODS: A total of 82 malignant pleural mesothelioma (MPM) and 179 advanced non-small cell lung cancer (aNSCLC) patients treated with PD-1 inhibitors as second or further line treatment were examined. Seventy-seven MPM patients treated with standard chemotherapy were analyzed as control cohort. Objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) were calculated. RESULTS: Among 253 patients with available data, statin use was associated with increased ORR (32% versus 18%, P = .02), PFS (median 6.7 versus 2.9 months, hazard ratio [HR] 0.57, 95% CI 0.39-0.83, P < .01), and OS (median 13.1 versus 8.7 months, HR 0.67, 95% CI 0.45-1.00, P = .05). In the control MPM cohort treated with chemotherapy (n = 77), no association was found. MPM patients who used statins showed improved ORR (22% versus 6%, P = .05), PFS (median 6.7 versus 2.4 months, P < .01), and OS (median not reached versus 6.0 months, P = .01). In aNSCLC patients, statin use was associated with improved ORR (40% versus 22%, P = .04) and PFS (median 7.8 versus 3.6 months, P = .03), but no significant difference in OS was found (median 13.1 versus 10.1 months, P = .30). Multivariable analysis confirmed the correlation between statin use and better PFS and OS in MPM and better PFS in aNSCLC. In the whole cohort, high but not low/moderate-intensity statins were associated with better OS compared to no user (P = .02 and P = .59, respectively). CONCLUSIONS: Our study showed that statins are associated with better clinical outcome in MPM and aNSCLC patients treated with PD-1 inhibitors in an intensity-dependent manner.

Ki67 (MIB-1) as a Prognostic Marker for Clinical Decision Making Before Extended Pleurectomy Decortication in Malignant Pleural Mesothelioma.

INTRODUCTION: The role of surgery for early stage malignant pleural mesothelioma (MPM) remains controversial. Current expert opinion is only to treat patients surgically as part of multimodality therapy. It is still challenging to identify patients who will not benefit from surgery. We specifically evaluated tumor-related parameters in combination with clinical parameters to identify prognostic markers for survival. METHODS: Clinical data of 27 consecutive patients with MPM treated with extended pleurectomy and decortication within a multimodality approach were collected and analyzed. Several tumor (immuno-)histopathologic characteristics were determined on resected tumor material, among which MTAP and Ki67 (MIB-1). Univariable and multivariable analyses served to correlate clinical and tumor-related parameters to overall survival (OS) and progression-free survival (PFS). RESULTS: The median PFS (mPFS) was 15.3, and the median OS (mOS) was 26.5 months. Patients with a Ki67 score greater than 10% had a significantly shorter PFS (mPFS = 8.81 versus 25.35 mo, p = 0.001) and OS (mOS 19.7 versus 44.5 mo, p = 0.002) than those with a Ki67 score less than or equal to 10. Receiver operating characteristic curve analysis for Ki67 revealed an area under the curve of 0.756 with a sensitivity of 90% and specificity of 71% for a cutoff of 10% for Ki67. Patients with loss of MTAP had a significantly shorter mPFS (9 versus 21.1 mo, p = 0.014) and mOS (19.7 versus 42.6 mo, p = 0.047) than those without MTAP loss. CONCLUSIONS: In our study, Ki67 was prognostic for OS and PFS in patients with MPM treated with extended pleurectomy/decortication in a multimodality approach. Determination of Ki67 before surgery combined with specific clinical parameters could assist in clinical decision making by identifying patients, with high Ki67, who are unlikely to benefit from surgery.

Cellular Immunotherapy and Locoregional Administration of CAR T-Cells in Malignant Pleural Mesothelioma.

Malignant pleural mesothelioma (MPM) is a treatment recalcitrant tumor with a poor overall survival (OS). Current approved treatment consists of first line chemotherapy that only modestly increases OS, illustrating the desperate need for other treatment options in MPM. Unfortunately, clinical studies that investigate the effectivity of checkpoint inhibitor (CI) treatment failed to improve clinical outcome over current applied therapies. In general, MPM is characterized as an immunological cold tumor with low T-cell infiltration, which could explain the disappointing results of clinical trials investigating CI treatment in MPM. Currently, many other therapeutic approaches, such as cellular therapies and cancer vaccines are investigated that could induce a tumor-specific immune response and increase of the number of tumor-infiltrating lymphocytes. In this review we will discuss these novel treatment approaches for MPM.

Nivolumab in pre-treated malignant pleural mesothelioma: real-world data from the Dutch expanded access program.

BACKGROUND: Randomized phase III trials are ongoing to investigate the efficacy of nivolumab in malignant pleural mesothelioma (MPM), but real-world data are still scarce. In this real-world study, we investigated the clinical outcomes of nivolumab treatment in pre-treated MPM patients. METHODS: Data from 107 nivolumab treated MPM patients within the Dutch expanded access program were retrospectively analyzed. Treatment was independent of programmed death ligand 1 (PD-L1) expression on tumor samples. Univariable and multivariable analyses were performed to evaluate the relationship between clinically important factors, baseline peripheral blood parameters and survival. The landmark method was used to compare the outcome of patients according to their radiological response. RESULTS: In the full cohort, the median progression-free survival (mPFS) was 2.3 months (95% CI: 1.6-2.9) and the median overall survival (mOS) was 6.7 months (95% CI: 6.2-10.0). After 12 weeks, the disease control rate (DCR) was 37% and the objective response rate (ORR) was 10%. PD-L1 status was determined in 33 patients (30%) and PD-L1 positivity (≥1%) was associated with an improved ORR (36% vs. 9%, P value 0.05), but not with PFS or OS. Low albumin was associated with worse OS (P value 0.002). Median OS was significantly longer for patients who had partial response to treatment (P value 0.0002). CONCLUSIONS: In this real-world analysis, ORR and mOS were lower compared to those obtained in phase II trials. However, exceptional survival rates were observed in patients who had a radiological response. Although we cannot determine whether prognostic or predictive, PD-L1 expression and albumin were associated with greater response rate and may represent useful biomarkers for nivolumab treatment in MPM.

T cell receptor repertoire characteristics both before and following immunotherapy correlate with clinical response in mesothelioma.

BACKGROUND: Malignant pleural mesothelioma (MPM) is a highly lethal malignancy in need for new treatment options. Although immunotherapies have been shown to boost a tumor-specific immune response, not all patients respond and prognostic biomarkers are scarce. In this study, we determined the peripheral blood T cell receptor ß (TCRß) chain repertoire of nine MPM patients before and 5 weeks after the start of dendritic cell (DC)-based immunotherapy. MATERIALS AND METHODS: We separately profiled PD1+ and PD1-CD4+ and CD8+ T cells, as well as Tregs and analyzed 70 000 TCRß sequences per patient. RESULTS: Strikingly, limited TCRß repertoire diversity and high average clone sizes in total CD3+ T cells before the start of immunotherapy were associated with a better clinical response. To explore the differences in TCRß repertoire prior-DC-therapy and post-DC-therapy, for each patient the TCRß clones present in the total CD3+ T cell fractions were classified into five categories, based on therapy-associated frequency changes: expanding, decreasing, stable, newly appearing and disappearing clones. Subsequently, the presence of these five groups of clones was analyzed in the individual sorted T cell fractions. DC-therapy primarily induced TCRß repertoire changes in the PD1+CD4+ and PD1+CD8+ T cell fractions. In particular, in the PD1+CD8+ T cell subpopulation we found high frequencies of expanding, decreasing and newly appearing clones. Conversion from a PD1- to a PD1+ phenotype was significantly more frequent in CD8+ T cells than in CD4+ T cells. Hereby, the number of expanding PD1+CD8+ T cell clones-and not expanding PD1+CD4+ T cell clones following immunotherapy positively correlated with overall survival, progression-free survival and reduction of tumor volume. CONCLUSION: We conclude that the clinical response to DC-mediated immunotherapy is dependent on both the pre-existing TCRß repertoire of total CD3+ T cells and on therapy-induced changes, in particular expanding PD1+CD8+ T cell clones. Therefore, TCRß repertoire profiling in sorted T cell subsets could serve as predictive biomarker for the selection of MPM patients that benefit from immunotherapy. TRIAL REGISTRATION NUMBER: NCT02395679.

Enhancing Dendritic Cell Therapy in Solid Tumors with Immunomodulating Conventional Treatment.

Dendritic cells (DCs) are the most potent antigen-presenting cells and are the key initiator of tumor-specific immune responses. These characteristics are exploited by DC therapy, where DCs are ex vivo loaded with tumor-associated antigens (TAAs) and used to induce tumor-specific immune responses. Unfortunately, clinical responses remain limited to a proportion of the patients. Tumor characteristics and the immunosuppressive tumor microenvironment (TME) of the tumor are likely hampering efficacy of DC therapy. Therefore, reducing the immunosuppressive TME by combining DC therapy with other treatments could be a promising strategy. Initially, conventional cancer therapies, such as chemotherapy and radiotherapy, were thought to specifically target cancerous cells. Recent insights indicate that these therapies additionally augment tumor immunity by targeting immunosuppressive cell subsets in the TME, inducing immunogenic cell death (ICD), or blocking inhibitory molecules. Therefore, combining DC therapy with registered therapies such as chemotherapy, radiotherapy, or checkpoint inhibitors could be a promising treatment strategy to improve the efficacy of DC therapy. In this review, we evaluate various clinical applicable combination strategies to improve the efficacy of DC therapy.

A multicenter, randomized, phase II/III study of dendritic cells loaded with allogeneic tumor cell lysate (MesoPher) in subjects with mesothelioma as maintenance therapy after chemotherapy: DENdritic cell Immunotherapy for Mesothelioma (DENIM) trial.

BACKGROUND: Malignant pleural mesothelioma (MPM) is an aggressive, treatment resistant neoplasm. The current treatment, consisting of antifolate and platinum-based chemotherapy, improves the median overall survival with only 3 months. Adjuvant bevacizumab generates an additional 2 months survival benefit. Checkpoint inhibitors (CI) have shown promising clinical effects in only a minority of patients. A possible reason is that MPM patients have low numbers of tumor-infiltrating CD8+ T-cells. Dendritic cell (DC) therapy can induce an immune response and activate tumor-specific CD8+ T-cells. Allogeneic mesothelioma tumor-lysate loaded DC therapy has proven effective in mice and safe and feasible in humans. We have designed a randomized, phase II/III, multicenter, open-label trial to examine the efficacy of DC therapy in humans with histologically proven MPM. METHODS: In this open-label, multicenter, randomized phase II/III trial patients will be randomized to receive either DC therapy plus best supportive care (BSC) or BSC alone according to the discretion of the local investigator after first line chemotherapy treatment. The primary end point will be overall survival. The secondary endpoints will be safety and tolerability, progression-free survival, overall response rate and quality of life. DISCUSSION: This phase II/III trial will determine whether DC therapy in patients with MPM is safe and effective as a maintenance treatment and subsequently might be a new treatment option for MPM.