Pamiparib as consolidation treatment after concurrent chemoradiotherapy of limited-stage small cell lung cancer: a single-arm, open-label phase 2 trial

Small cell lung cancer (SCLC) is highly invasive with poor prognosis, and its treatment has historically been hindered due to the absence of targetable driver genomic alterations. However, the high genomic instability and replication stress in SCLC have made poly(ADP-ribose) polymerases (PARPs) inhibitors a focus of research. Pamiparib is an orally available PARP1/2 inhibitor with high selectivity, strong PARP trapping activity, and excellent brain penetration. Utilizing pamiparib as consolidation maintenance therapy in limited-stage SCLC holds promise for improving survival outcomes and offering a viable therapeutic approach. This single-arm, open-label phase II trial will enroll patients aged 18–75 years with histologically/cytologically confirmed, limited-stage SCLC who have not progressed following definitive platinum-based cCRT and have an ECOG PS of 0 or 1. Patients will be excluded if they have histologically confirmed mixed SCLC or NSCLC, or have undergone previous tumor resection, or can be treated with surgery or stereotactic body radiation therapy/stereotactic ablative radiation therapy. Participants will receive pamiparib 40 mg twice daily every 3 weeks within 2 to 6 weeks after cCRT for up to 1 year or until disease progression according to RECIST v1.1. The primary endpoint is the 1-year progression-free survival (PFS) rate assessed by investigators per RECIST v1.1. Secondary endpoints include PFS, objective response rate, and duration of response assessed by investigators per RECIST 1.1, overall survival, time to distant metastasis, and safety. The study will provide valuable data on the feasibility, safety, and effectiveness of pamiparib as a consolidation therapy after cCRT in patients with LS-SCLC. The correlation between molecular typing or gene expression profile of the disease and curative response will be further explored. NCT05483543 at clinicaltrials.gov.