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Robert anton Belderbos



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    MA05 - Update on Clinical Trials and Treatments (ID 123)

    • Event: WCLC 2019
    • Type: Mini Oral Session
    • Track: Mesothelioma
    • Presentations: 1
    • Now Available
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      MA05.09 - Real-World Data of Nivolumab and Pembrolizumab in Chemotherapy Pre-Treated Mesothelioma Patients (Now Available) (ID 1918)

      13:30 - 15:00  |  Author(s): Robert anton Belderbos

      • Abstract
      • Presentation
      • Slides

      Background

      Both nivolumab and pembrolizumab have shown positive results in phase II studies in patients following chemotherapy in mesothelioma patients. However, these studies were done in a limited number of patients with strict inclusion criteria, while reports show a difference between real life and study setting.

      Method

      In our mesothelioma center, we treated patients that progressed during or after chemotherapy treatment with nivolumab 3mg/kg once every 2 weeks independent of PD-L1 expression or with pembrolizumab 200mg once every 3 weeks when PD-L1 expression was ³1%, both in Early Patient Access programs. All patients were pre-treated with at least one cycle of platinum/folate treatment. CT scan evaluation was done using modified RECIST every 6 weeks.

      Result

      In total, we treated 78 patients with nivolumab and 13 patients with pembrolizumab. Median age of the patients was 71 years (29-85) at start of the checkpoint inhibitor treatment, 80 (88%) were male. Performance status was ECOG 0 in 19 patients, ECOG 1 in 57 patients, ECOG 2 in 9 patients. Data analysis thus far showed 9 partial responses (10%) and 31 patients with stable disease (29%) and therefore a disease control rate of 39% at twelve weeks of treatment. Median progression free survival is 2.4 months and median overall survival 6,3 months. Median duration of response had not been reached yet. These data will be updated for the meeting. Two cases of pseudoprogression were seen on checkpoint inhibition therapy where progression according to modified RECIST was followed by response during continuation of PD-1 therapy. Toxicity was in line with historical data.

      Conclusion

      We believe that this large dataset, using real-world data, can truly give an insight in the clinical benefit of these immune checkpoint inhibitors. In comparison with the published phase I and II trials on nivolumab and pembrolizumab, the response rates appear to be lower in a real-life setting. However, clinically meaningful and durable responses are seen in a population that has no other proven therapy options.

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    MA12 - New Frontiers from Pathology to Genomics (ID 138)

    • Event: WCLC 2019
    • Type: Mini Oral Session
    • Track: Mesothelioma
    • Presentations: 1
    • Now Available
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      MA12.09 - Checkpoint Inhibitors Synergize with Dendritic Cell-Therapy in Pre-Clinical Models and Mesothelioma Patients (Now Available) (ID 2425)

      14:00 - 15:30  |  Presenting Author(s): Robert anton Belderbos

      • Abstract
      • Presentation
      • Slides

      Background

      Malignant Pleural Mesothelioma (MPM) is a lethal, treatment resistant neoplasm. Checkpoint inhibitors (CI) have shown promising clinical effects in a minority of patients. It is hypothesized that low response rates to CI are correlated to low numbers of tumor-infiltrating T-cells in MPM patients. Dendritic cell (DC) therapy instigates an immune response and activates tumor-specific T-cells. DC therapy has proven to be effective in pre-clinical models and in a subset of MPM patients. Upregulation of PD-L1 and PD-1 co-inhibitory checkpoints may suppress DC-therapy induced anti-tumor immune response and limit clinical efficacy. To investigate this, we conducted a preclinical and clinical study to evaluate the clinical and immunological effects of DC therapy combined with CI.

      Method

      Immune competent CBA/J mice were orthotopically injected with a syngeneic mesothelioma cell line. Mice were treated with DC-therapy alone or in combination anti-PD-L1 antibodies at high tumor load when DC-monotherapy was found to be ineffective. Peripheral blood and tumors were obtained for flow cytometric analysis and survival was monitored.
      In a clinical setting, nine patients that received DC therapy were sequentially treated with CI. Progression free survival (PFS) was determined from start of CI, using the modified RECIST criteria.

      Result

      Tumors of mice treated with DC-therapy exhibited a three-fold increase in CD8+ T-cell infiltration which was paralleled by heightened expression of PD-L1 on tumor cells (r2=0.69, p=0.0015). Whereas both anti-PD-L1 and DC-monotherapies were ineffective in prolonging survival in our model, combination immunotherapy did (median OS: 24 vs 35 days, p=0.0063). Immune monitoring analyses demonstrated a synergistic increase in proliferation and activation of circulating T-cell following combination therapy. In the clinical trial 3 patients had partial response, 5 patients had stable disease and 1 patient had progressive disease. Median PFS was 5,2 months and median OS was 17,5 months. Currently 3 patients are still alive and two patients are still progression free. There were no grade 3/4 adverse events. PD-L1 expression in tumor biopsies was increased after DC therapy in two of the three responders to CI.

      Conclusion

      In a murine model the synergy between DC therapy and CI was proven and efficacy was driven by activation of CD4+ and CD8+ positive cells. In humans, CI after DC therapy is safe and feasible. Disease control was seen in 8 out of 9 patients treated with CI after DC therapy. DC therapy induces tumor-specific CD8+ T-cell proliferation which is correlated to PD-L1 expression on tumor cells and possibly synergizes with CI treatment.

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