P1.12-04 A Ph3 Study of Niraparib as Maintenance Therapy in 1L Platinum Responsive Extensive Disease Small Cell Lung Cancer Patients

Abstract

Small cell lung cancer (SCLC) accounts for 15% of lung cancer, characterized by early dissemination and rapid development of chemo-resistant disease after platinum response (60-80%). Less than 2% of extensive disease SCLC (ED-SCLC) patients survive 5 years. The bi-allelic loss or inactivation of TP53 and RB1 is common in SCLC, the poly(ADP-ribose) polymerase-1 (PARP-1), a critical DNA damage repair enzyme, is highly expressed in SCLC, and SCLC is sensitive to platinum based chemotherapy, suggesting that the defect in DNA damage repair pathways plays an important role in SCLC. ZL2306/ Niraparib is a highly selective PARP-1/2 inhibitor which was exclusively licensed for development in China by Zai Laboratory from TESARO. In SCLC PDX model, niraparib demonstrated anti-tumor activities as monotherapy. In addition, niraparib demonstrated promising tumor growth inhibition in maintenance post platinum treatment in platinum sensitive SCLC PDX models. Clinically, in phase III NOVA study, niraparib demonstrated clear clinical benefit as maintenance treatment by significantly extending progression free survival in all platinum-sensitive recurrent ovarian cancer patients regardless gBRCA or HRD status which led to the approval by FDA and EMA in ovarian cancer. It is suggested that niraparib maintenance therapy could provide potential clinical benefit in platinum responsive SCLC. ZL-2306-005 is a randomized double-blind multi-center phase 3 study to evaluate the efficacy and safety of niraparib versus placebo as maintenance therapy in ED-SCLC patients who have had responses to platinum based chemotherapy. Approximately 590 Chinese patients with histologically or cytologically confirmed ED-SCLC who have achieved either complete response or partial response to their platinum based chemotherapy to their newly diagnosed disease will be randomized (2:1) to 2 groups, receiving either ZL-2306 or placebo in ZL-2306-005 study. Patients need to complete 4 cycles of etoposide + cisplatin/ carboplatin. All patients will be stratified by gender, LDH level and history of prophylactic cranial irradiation. ZL-2306 will be started with 300mg PO QD for patients with a baseline body weight ≥77 kg and a baseline platelet count ≥150,000/μL, or 200 mg PO QD for patients with a baseline body weight <77 kg or a baseline platelet count <150,000/μL based on RADAR analysis in NOVA study. Patients will remain on treatment until disease progression or intolerable toxicity. The co-primary endpoints are PFS assessed by independent central radiologic review and OS; the secondary endpoints are PFS assessed by investigator, CFI, QoL, safety and tolerability. Section not applicable Section not applicable