Randomized phase II study of maintenance vandetanib (ZD6474) in small cell lung cancer (SCLC) patients who have a complete or partial response to induction therapy: NCIC CTG BR.20

7522 Background: Vandetanib (V) is an inhibitor of vascular endothelial and epidermal growth factor receptors. This trial sought to determine whether maintenance V, given after standard chemotherapy (CT) and radiation (RT), prolonged progression-free survival (PFS) in responding patients with SCLC. Secondary endpoints: overall survival (OS) and toxicity. Methods: Phase II randomized, study of V 300 mg PO daily or placebo (P). Eligibility: complete (CR) or partial response (PR) to platinum-based CT, ECOG PS 0–2 and completion of RT (thoracic or prophylactic cranial). Statistics: 80% power to detect a 2.5 months improvement in median PFS (estimate for P of 4 months) using a 1-sided 10% level test (100 eligible patients; 77 events). Results: Between May 2003 and March 2006, 107 patients were accrued from 17 centres. Median follow up: 13.5 months. 46 had limited disease (LD); 61 extensive disease (ED). There were fewer PS 0 patients (11 vs. 20), and fewer had CR to initial CT (4 vs. 8) in the V arm. V patients were more likely to experience toxicity and require dose modification. The most frequent toxicities leading to dose modifications were gastrointestinal and rash. Clinically asymptomatic QTc prolongation was observed in 8 V patients. 83 of 107 patients developed progressive disease (43 on V; 40 on P). The median PFS for V was 2.7 months (80% C.I.: 1.1 –4.5) and 2.8 months for P (80% C.I.: 1.9 –5.6); estimated hazard ratio (HR) was 1.01 for V vs P (80% C.I.: 0.75 –1.36, 1-sided P-value = 0.51). Median OS for V was 10.6 months vs. 11.9 months for P; HR was 1.43 for V vs. P (80% C.I.: 1.00 –2.05, 1-sided P-value = 0.90). In a planned subgroup analysis, a significant interaction was noted (P-value = 0.01); with LD patients randomized to V having a longer OS (HR: 0.45, 1-sided P-value = 0.07), whereas ED patients randomized to V had a shorter OS compared to P (HR: 2.27, 1-sided P-value = 0.996). Conclusion: V failed to demonstrate efficacy as maintenance therapy for SCLC. Future targeted therapies should probably be explored concurrently with chemotherapy. This study was supported by the Canadian Cancer Society and AstraZeneca. [Table: see text]