MECHANISM OF ACTION — Binding of programmed death ligand-1 (PD-L1) and PD-L2 to PD-1 on T cells suppresses T-cell proliferation and cytokine production. Pembrolizumab binds to PD-1 on T cells, blocking its interaction with PD-L1 and PD-L2 and restoring T-cell antitumor immune responses. Keytruda Qlex contains berahyaluronidase alfa, an endoglycosidase, which increases permeability of subcutaneous tissue and the absorption of pembrolizumab.

CLINICAL STUDIES — FDA approval of Keytruda Qlex was based on the results of an open-label trial in 377 patients ≥18 years old with newly-diagnosed metastatic non-small cell lung cancer (NSCLC) and no EGFR, ALK, or ROS1 alterations. Patients were randomized to receive SC pembrolizumab 790 mg or IV pembrolizumab 400 mg once every 6 weeks, each in addition to platinum-based chemotherapy. Overall exposure and trough pembrolizumab serum concentrations with SC administration were noninferior to those with IV administration. The overall response rate was 45.4% with SC pembrolizumab and 42.1% with IV pembrolizumab. Progression-free survival and overall survival were also similar in both groups.1

ADVERSE EFFECTS — Common adverse effects in patients treated with subcutaneous pembrolizumab and chemotherapy in the clinical trial included nausea, fatigue, and musculoskeletal pain. Injection-site reactions occurred in 2.4% of patients. Patients who received SC pembrolizumab were less likely than those who received IV pembrolizumab to dicontinue treatment due to adverse effects (8.4% vs 15.1%).1

DOSAGE, ADMINISTRATION, AND COST — Keytruda Qlex is supplied in 395 mg/2.4 mL and 790 mg/4.8 mL single-dose vials. It is given subcutaneously over 1-2 minutes once every 3 or 6 weeks by a healthcare provider. IV pembrolizumab is generally given over 30 minutes once every 3 or 6 weeks. The wholesale acquisition cost (WAC) for one 395-mg vial of Keytruda Qlex is $12,031; Keytruda costs about $12,000 for a 3-week treatment cycle (200 mg every 3 weeks).2

CONCLUSION — Keytruda Qlex, the new subcutaneous formulation of pembrolizumab, appears to be similar in efficacy to IV pembrolizumab (Keytruda). It offers a shorter administration time and could be a more convenient option for treatment of adults with various solid tumor cancers.