Second-line pazopanib in patients with relapsed and refractory small-cell lung cancer: a multicentre phase II study of the Hellenic Oncology Research Group.

BACKGROUND

Pazopanib is a tyrosine kinase inhibitor with antiangiogenic activity. Vascular endothelial growth factor expression is increased in SCLC and is correlated with poor prognosis. The efficacy and tolerance of second-line pazopanib in SCLC was evaluated.

PATIENTS AND METHODS

Patients with platinum-sensitive (cohort A; n=39) and -resistant/refractory (cohort B; n=19) SCLC were enrolled in a multicentre phase II study. The primary end point was the progression-free survival rate (PFS-R) at week 8 in each cohort. Pazopanib (800 mg per day per os) was administered until progressive disease (PD). Circulating tumour cells (CTCs) were enumerated using the Cellsearch assay.

RESULTS

All patients were evaluable for response and toxicity. In the intention-to-treat analysis, eight (13.8%) patients achieved partial response (PR) (95% confidence interval (CI): 5.0-22.7), 20 (34.5%) stable disease (SD) and 30 (51.7%) PD. Accrual in cohort B was halted because the hard-stop rule was met; in cohort A, the PFS-R was 59% (95% CI: 43.5-74.4; PR=7, SD=16). Nine (23.1%) patients received pazopanib for >6 months and 3 of them for >12 months. One pazopanib cycle resulted to a significant decrease to the number of patients with ⩾5 CTCs/7.5 ml of blood (20%) compared with baseline (50%). The median PFS and OS for all patients was 2.5 months (95% CI: 1.9-3.1 months) and 6.0 months (95% CI: 3.8-8.2 months), respectively (cohort A: PFS=3.7 months and OS=8.0 months). No unexpected toxicity was observed.

CONCLUSIONS

Second-line treatment with pazopanib in platinum-sensitive SCLC is well tolerated and resulted in promising objective responses and disease control; CTC enumeration might serve as a reliable surrogate biomarker of response.