Safety and Tolerability of PD-1/PD-L1 Inhibitors Compared with Chemotherapy in Patients with Advanced Cancer: A Meta-Analysis

Background: Compared with chemotherapy, significant improvement in survival outcomes with the programmed death receptor-1 (PD-1) inhibitors nivolumab and pembrolizumab and the programmed death-ligand 1 (PD-L1) inhibitor atezolizumab has been shown in several types of advanced solid tumors. We conducted a systematic review and meta-analysis to compare safety and tolerability between PD-1/PD-L1 inhibitors and chemotherapy.

Methods: PubMed and American Society of Clinical Oncology (ASCO) databases were searched 1966 to September 2016. Eligible studies included randomized controlled trials (RCTs) comparing single-agent U.S. Food and Drug Administration-approved PD-1/PD-L1 inhibitors (nivolumab, pembrolizumab, or atezolizumab) with chemotherapy in cancer patients reporting any all-grade (1-4) or high-grade (3-4) adverse events (AEs), all- or high-grade treatment-related symptoms, hematologic toxicities and immune-related AEs, treatment discontinuation due to toxicities, or treatment-related deaths. The summary incidence, relative risk, and 95% confidence intervals were calculated.

Results: A total of 3,450 patients from 7 RCTs were included in the meta-analysis: 4 nivolumab, 2 pembrolizumab, and 1 atezolizumab trials. The underlying malignancies included were non-small cell lung cancer (4 trials) and melanoma (3 trials). Compared with chemotherapy, the PD-1/PD-L1 inhibitors had a significantly lower risk of all- and high-grade fatigue, sensory neuropathy, diarrhea and hematologic toxicities, all-grade anorexia, nausea, and constipation, any all- and high-grade AEs, and treatment discontinuation. There was an increased risk of all-grade rash, pruritus, colitis, aminotransferase elevations, hypothyroidism, and hyperthyroidism, and all- and high-grade pneumonitis with PD1/PD-L1 inhibitors.

Conclusion: PD-1/PD-L1 inhibitors are overall better tolerated than chemotherapy. Our results provide further evidence supporting the favorable risk/benefit ratio for PD-1/PD-L1 inhibitors. The Oncologist 2017;22:470-479 IMPLICATIONS FOR PRACTICE: We conducted a systematic review and meta-analysis to compare summary toxicity endpoints and clinically relevant adverse events between programmed death receptor-1 (PD-1)/programmed death-ligand 1 (PD-L1) inhibitors and chemotherapy. PD1/PD-L1 inhibitors were associated with a lower risk of treatment-related symptoms (fatigue, anorexia, nausea, diarrhea, constipation, and sensory neuropathy) but a higher risk of immune-related adverse events (AEs). Summary toxicity endpoints favor PD1/PD-L1 inhibitors (any all- and high-grade AEs and treatment discontinuation). PD1/PD-L1 inhibitors are overall better tolerated than chemotherapy. In addition to efficacy data from trials, our findings provide useful information for clinicians for well-balanced discussions with their patients on the risks and benefits of treatment options for advanced cancer.