The anti-disialoganglioside (GD2) antibody dinutuximab (D) for second-line treatment (2LT) of patients (pts) with relapsed/refractory small cell lung cancer (RR SCLC): Results from part II of the open-label, randomized, phase II/III distinct study.

Abstract

9017 Background: Although SCLC is highly responsive to initial therapy, most pts relapse < 1 y. Topotecan (T) and irinotecan (I) are used in 2LT of SCLC; however, treatment response is low: ≤10-25% and median survival is ~4-5 months. Preclinical studies support GD2 as an SCLC target. This study evaluated the combination of D+I vs. I alone or T alone in 2LT of SCLC pts. Methods: Pts with RR SCLC, Eastern Cooperative Oncology Group 0-1, were randomized 2:2:1 to receive D 16-17.5 mg/m2 intravenously (IV) plus I 350 mg/m2 IV (Day 1 q21d), I 350 mg/m2 IV (Day 1 q21d), or T 1.5 mg/m2 IV (Days 1-5 q21d). Randomization was stratified by duration of response to prior platinum therapy. Primary endpoint was overall survival (OS) in pts treated with D+I vs. I alone and was analyzed using stratified log-rank test and COX regression. Secondary endpoints included progression-free survival (PFS), objective response rate (ORR), and clinical benefit rate, ORR + stable disease (CBR). Safety was assessed. Results: 471 pts were randomized to D+I (n = 187), I (n = 190), or T (n = 94). Baseline characteristics were balanced (24.2% women; mean ± SD age 61.6 ± 8.7 y). Median OS was similar in pts receiving D+I (6.9 [3.5,10.9] months) vs. I alone (7 [3.6,13.1] months) (HR [95% CI]: 1.12 [0.9,1.4]; P = 0.3132) or T alone (7.4 [3.8,12.8] months) (HR [95% CI]: 1.05 [0.8,1.37]; P = 0.7233). Median PFS was similar in pts receiving D+I (3.5 [1.5,6.2] months) vs. I (3 [1.4,5.7] months) or T (3.4 [1.6, 6.1] months) alone. ORR was similar in pts receiving D+I (17.1%) vs. I (18.9%) or T (20.1%) alone. CBR was similar in pts receiving D+I (67.4%) vs. I (58.9%) or T (68.1%) alone. Grade 3 or higher adverse events were experienced by 77% D+I, 69.5% I, and 86.4% T pts. Conclusions: Treatment with D+I was not superior to established 2LT for RR SCLC. Exploratory analyses are ongoing to evaluate GD2 expression in circulating tumor cells, select protein biomarkers, and any correlative impact on observed response. Clinical trial information: NCT03098030.