Background: There is no recommended therapy for malignant pleural mesothelioma that has progressed after first-line pemetrexed and platinum-based chemotherapy. Disease control has been less than 30% in all previous studies of second-line drugs. Preliminary results have suggested that anti-programmed cell death 1 (PD-1) monoclonal antibody could be efficacious in these patients. We thus aimed to prospectively assess the anti-PD-1 monoclonal antibody alone or in combination with anti-cytotoxic T-lymphocyte protein 4 (CTLA-4) antibody in patients with malignant pleural mesothelioma.
Methods: This multicentre randomised, non-comparative, open-label, phase 2 trial was done at 21 hospitals in France. Eligible patients were aged 18 years or older with an Eastern Cooperative Oncology Group performance status of 0-1, histologically proven malignant pleural mesothelioma progressing after first-line or second-line pemetrexed and platinum-based treatments, measurable disease by CT, and life expectancy greater than 12 weeks. Patients were randomly allocated (1:1) to receive intravenous nivolumab (3 mg/kg bodyweight) every 2 weeks, or intravenous nivolumab (3 mg/kg every 2 weeks) plus intravenous ipilimumab (1 mg/kg every 6 weeks), given until progression or unacceptable toxicity. Central randomisation was stratified by histology (epithelioid vs non-epithelioid), treatment line (second line vs third line), and chemosensitivity to previous treatment (progression ≥3 months vs <3 months after pemetrexed treatment) and used a minimisation method with a 0·8 random factor. The primary outcome was the proportion of patients who achieved 12-week disease control, assessed by masked independent central review; the primary endpoint would be met if disease control was achieved in at least 40% of patients. The primary endpoint was assessed in the first 108 eligible patients. Efficacy analyses were also done in the intention-to-treat population and safety analyses were done in all patients who received at least one dose of their assigned treatment. This trial is registered at ClinicalTrials.gov, number NCT02716272.
Findings: Between March 24 and August 25, 2016, 125 eligible patients were recruited and assigned to either nivolumab (n=63) or nivolumab plus ipilimumab (n=62). In the first 108 eligible patients, 12-week disease control was achieved by 24 (44%; 95% CI 31-58) of 54 patients in the nivolumab group and 27 (50%; 37-63) of 54 patients in the nivolumab plus ipilimumab group. In the intention-to-treat population, 12-week disease control was achieved by 25 (40%; 28-52) of 63 patients in the nivolumab group and 32 (52%; 39-64) of 62 patients in the combination group. Nine (14%) of 63 patients in the nivolumab group and 16 (26%) of 61 patients in the combination group had grade 3-4 toxicities. The most frequent grade 3 adverse events were asthenia (one [2%] in the nivolumab group vs three [5%] in the combination group), asymptomatic increase in aspartate aminotransferase or alanine aminotransferase (none vs four [7%] of each), and asymptomatic lipase increase (two [3%] vs one [2%]). No patients had toxicities leading to death in the nivolumab group, whereas three (5%) of 62 in the combination group did (one fulminant hepatitis, one encephalitis, and one acute kidney failure).
Interpretation: Anti-PD-1 nivolumab monotherapy or nivolumab plus anti-CTLA-4 ipilimumab combination therapy both showed promising activity in relapsed patients with malignant pleural mesothelioma, without unexpected toxicity. These regimens require confirmation in larger clinical trials.
Funding: French Cooperative Thoracic Intergroup.
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