Clinical Topics & News

Evaluating PD-1 Inhibitors

Researchers find positive safety and efficiency results for patients with malignant melanoma treated with PD-1 antibody monotherapy.


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.

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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.

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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.
doi: 10.1371/journal.pone.0160485.

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