PD-1 antibodies are being touted as a promising immunotherapeutic approach for treating malignant melanoma among other cancers. The antibodies target proteins that promote programmed cell death and activate the immune system to attack tumors.
To find out more about the efficacy and safety of PD-1 antibody treatment, researchers from Xiamen University, Chinese Academy of Medical Sciences, and Peking Union Medical College, China, reviewed data from 5 multicenter, randomized clinical trials involving 2,828 patients. In 2 trials, patients were previously untreated; in the other 3, patients had progression after anti-CTLA-4 treatment or had received no more than 1 previous systemic therapy. Patients in the experimental groups received nivolumab or pembrolizumab; patients in the control groups received ipilimumab or chemotherapy.
In all 5 trials, the researchers noted significant differences between the anti-PD-1 groups and the control groups. The PD-1 antibody treatment was associated with a significantly better overall response rate (ORR): 40.0% in patients on nivolumab 3 mg/kg IV every 2 weeks as front-line therapy and 31.6% in those who received nivolumab at the same dosage after progression from anti-CTLA-4 treatment. Response was improved whether the drug was used as first-line treatment or for refractory/relapsed melanoma.
Patients in the PD-1 groups also had a significantly greater rate of progression-free survival (PFS) compared with those who received other treatments, such as chemotherapy and ipilimumab. The median PFS was > 4.7 months in the nivolumab group and > 3.7 months in the pembrolizumab group. In 2 trials, the ORR among patients receiving pembrolizumab was between 23.3% and 33.2%; different dosages improved the overall response rate in both untreated and relapsed/refractory patients.
The most common adverse events (AEs) were fatigue, diarrhea, pruritus, rash, and nausea. Patients treated with nivolumab reported significantly fewer AEs. Although a high dosage or short intermission of pembrolizumab extended the median PFS, a subgroup analysis of different doses revealed a significant dose-dependent increase in AEs.
Lin Z, Chen X, Li Z, et al. PLoS One . 2016;11(8):e0160485.