Pembrolizumab in the management of metastatic melanoma

A snapshot of the PD-1/PD-L1 pathway

Cancer cells can evade the attack from host immune systems via hijacking the regulatory circuits mediated by immune checkpoints. Therefore, reactivating the antitumor immunity by blockade of immune checkpoints is considered as a promising strategy to treat cancer. Programmed death protein 1 (PD-1) and its ligand programmed death-ligand 1 (PD-L1) are critical immune checkpoint proteins that responsible for negative regulation of the stability and the integrity of T-cell immune function. Anti-PD-1/PD-L1 drugs have been developed for immune checkpoint blockade and can induce clinical responses across different types of cancers, which provides a new hope to cure cancer. However, the patients' response rates to current anti-PD-1 or anti-PD-L1 therapies are still low and many initial responders finally develop resistance to these therapies. In this review, we provides a snapshot of the PD-1/PD-L1 molecular structure, mechanisms controlling their expression, signaling modulated by PD-1/PD-L1, current anti-PD-1/PD-L1 therapies, and the future perspectives to overcome the resistance.

Immune checkpoint inhibitors-associated risk of immune-related hypothyroidism in older patients with advanced melanoma: a real-world analysis of US SEER-Medicare data

Background: The risk of immune-related(ir)-hypothyroidism in older patients with advanced melanoma treated with anti-CTLA4 or anti-PD1 therapies is poorly understood, especially in the real-world setting.Research design and methods: We identified older patients (≥65 years) diagnosed with advanced melanoma between 2011-2015 and treated with anti-CTLA4 or anti-PD1 agents in the SEER-Medicare database. Applying probability-of-treatment-weighting for confounder adjustment and proportional hazards models, we estimated the risk of ir-hypothyroidism between treatment initiation and up to 90 days from last dose between anti-PD1 and anti-CTLA4 users.Results: Of 210 older patients with advanced melanoma identified, 164 received anti-CTLA4 (ipilimumab) and 46 anti-PD1 agents (11 nivolumab, 35 pembrolizumab). There was no statistically significant difference in ir-hypothyroidism risk between anti-PD1 and anti-CTLA4 users (HR=2.15, 95%CI=0.83-5.53). Pairwise medication comparisons showed a lower risk among ipilimumab versus nivolumab (HR=0.15, 95%CI=0.06-0.40) and pembrolizumab versus nivolumab users (HR=0.13, 95%CI=0.03-0.55). Sensitivity analyses using an all-stages melanoma cohort did not show a difference in ir-hypothyroidism risk between medication classes and individual medications.Conclusions:This retrospective claims data analysis revealed no statistically significant difference in ir-hypothyroidism risk between anti-CTLA4 or anti-PD1 users. However, patients with advanced melanoma treated with ipilimumab or pembrolizumab may have a lower ir-hypothyroidism risk compared to nivolumab users.

Efficacy of pembrolizumab for advanced/metastatic melanoma: a meta-analysis

This study evaluates the efficacy of pembrolizumab for the treatment of advanced/metastatic melanoma. The literature search was conducted in electronic databases for studies that evaluated the efficacy and safety of pembrolizumab either alone or in combination with other treatments advanced/metastatic melanoma patients. Random-effects meta-analyses were performed to achieve pooled effect sizes of response and survival rates. The overall objective response rate (ORR) was 34.2% [95% confidence interval (CI): 30.4, 38.0]. However, ORR differed with respect to the history of prior systemic therapy. ORR was lower in studies with over 50% patients with prior therapy (25.5% [22.4, 28.5]) than in studies with under 50% patients with prior therapy (40.1% [34.1, 46.1]). ORR was higher in pembrolizumab monotherapy (32.9% [28.1, 37.7]) than in pembrolizumab-ipilimumab combination (27.6% [24.0, 31.2]). Overall ORR was inversely associated with visceral metastasis and prior systemic therapy. With pembrolizumab treatment, either alone or in combination, the progression-free survival (PFS) was 5.73 months; 12-, 24-, and 60-month PFS rate were 44%, 27%, and 25%, respectively; and 12-, 24-, and 60-month overall survival rates were 65%, 50%, and 41%, respectively. The percentage of AEs that led to treatment discontinuation was 13%. Pembrolizumab monotherapy is a valuable option for the treatment of advanced/metastatic melanoma patients.