Real-world efficacy and safety of low-dose pembrolizumab in patients with advanced and refractory gynecologic cancers

The approved standard dose of pembrolizumab (200 mg administrated every 3 weeks) for cancer treatment imposes a significant financial burden on patients. However, no study has analyzed the clinical outcomes of low-dose pembrolizumab among individuals diagnosed with gynecologic cancer. The primary objective of this study was to assess the effectiveness and safety of a low-dose pembrolizumab regimen in real-world clinical practice. We retrospectively assessed the efficacy and safety data of patients with gynecologic malignancies who received pembrolizumab between 2017 and 2022 at Kaohsiung Chang Gung Memorial Hospital. Furthermore, we conducted a comparative analysis of the objective response rate (ORR) and progression-free survival (PFS) between patients with deficient mismatch repair (dMMR) and proficient MMR (pMMR). A total of thirty-nine patients were included and received pembrolizumab at fixed dosages of 50 mg (5.1%), 100 mg (84.6%) and 200 mg (10.3%) per cycle. Compared to the pMMR group, the dMMR group exhibited a tendency toward improved ORR (45.5% vs. 13.0%, p = 0.074), and notably, the median duration of response remained unreached. There was no significant difference in PFS between the dMMR and pMMR groups; however, the patients with dMMR in tumor tissue had a trend of better survival (p = 0.079). Incidence of immune-related adverse events (irAEs) of any grade was observed in 13 patients (33.3%), with 3 individuals (7.7%) experiencing grade 3 or 4 events. Low-dose pembrolizumab may be a cost-effective and safe treatment option without compromising clinical outcomes in patients with refractory gynecologic cancers.