Randomized phase II study of IV topotecan versus CRLX101 in the second-line treatment of recurrent extensive-stage small cell lung cancer (ES-SCLC).

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TPS7610 Background: SCLC remains an area of high unmet medical need with an aggressive clinical course and < 10% 5-year overall survival. In the U.S., topotecan (Hycamtin, GlaxoSmithKline) is the reference standard for treatment of chemotherapy (C)-sensitive (S) relapsed disease but its use remains compromised by toxicity. There currently exists no standard therapy for patients (pts) with C-resistant (R) disease (relapse occurring < 60 days from last C). CRLX101 is a novel cyclodextrin-containing polymer conjugate of camptothecin (CPT) that self-assembles into nanoparticles and delivers sustained levels of active CPT into cancer cells while substantially reducing systemic exposure. In vitro and in vivo data suggest superior activity of CRLX101 compared to approved agents in multiple animal tumor models including SCLC. A monotherapy recommended phase 2 dose of 15 mg/m2 IV every 2 weeks has now been administered to over 150 cancer pts across five ongoing phase 2 clinical trials. Methods: This ongoing, randomized phase 2 clinical trial compares the effect on progression free survival (PFS) of 2nd-line treatment with IV CRLX101 (15 mg/m2 on days 1 and 15 every 28 days) to IV topotecan (1.5 mg/m2 on days 1-5 every 21 days) in pts with CS relapsed ES-SCLC. In parallel, the effect of 2nd-line CRLX101 on 3-mo. PFS rate of pts with CR relapsed ES-SCLC will be evaluated. Secondary objectives in both cohorts include evaluation of objective response rates (by RECIST v1.1), overall survival, and safety. In the randomized cohort, 112 pts (56/arm) will be enrolled in order to achieve 90% power to detect an improvement in median PFS from 3 to 5 mos. (HR=0.60). An interim analysis will be performed after 1/2 of expected PFS events have occurred. Pts with CR disease will all receive CRLX101 and the trial will employ a 2-stage design: 14 pts will be enrolled in stage 1 and the study will be terminated if ≤ 3 pts remain progression free at 3 mos. Otherwise, an additional 30 pts will be enrolled and if ³ 15/44 (34%) pts remain progression free at 3 mos., the drug will be considered worthy of further investigation. The first patient on this clinical trial was enrolled on January 30, 2013. Clinical trial information: NCT# is pending.