Differential crizotinib efficacy among ROS1 fusion partners in ROS1-positive non-small cell lung cancer.

Abstract

9067 Background: ROS1 rearrangement non–small-cell lung cancers can be effectively treated with ALK inhibitor such as crizotinib, but the response magnitude and duration are heterogeneous. Several ROS1 fusion partners have been identified, but few studies have focused on the effects of different fusion partners on the efficacy of crizotinib. Methods: Among 49 RT-PCR assay ROS1 rearrangement patients treated with crizotinib between April 2014 and November 2016, we identified 36 patients with tumor specimens that could be evaluated for the presence of different ROS1 fusion partners by Sanger sequencing. Patients continued crizotinib until RECIST-defined progression. We retrospectively evaluated the efficacy of crizotinib on the basis of the objective response rate(ORR), progression-free survival (PFS) and overall survival (OS) according to the different ROS1 fusion partners. Results: The most frequent ROS1 fusion partner was CD74-ROS1 (CD74-E6; ROS1-E34) in 16 patients (44.4%), followed by EZR-ROS1 (EZR-E10; ROS1-E34) in 7 patients (19.4%), SDC4 (SDC4-E2; ROS1-E32) in 4 patients (12%), SLC34A2-ROS1 (SLC34A2-E14del; ROS1-E32) in 2 patients (5.6%) and TPM3 (TPM3-E8; ROS1-E35) in 2 patients (5.6%). We also found that SDC4+EZR (SDC4-E2; ROS1-E32/EZR-E10; ROS1-E34) in 2 patients (5.6%), dual CD74-ROS1 (CD74-E6; ROS1-E32/34) in 2 patients (5.6%), CD74+SDC4 (SDC4-E2; ROS1-E32/CD74-E6; ROS1-E34) in 1 patient (2.8%). ORR was 83.3% in all patients, whereas it was 70.58% and 92.35% in the CD74 and non–CD74 groups, respectively (P = 0.17). The median PFS was longer in non–CD74 than in those with CD74 (median PFS, 17.67 months [95% CI, 12.14 to 23.19 ] vs 19.30 months [95% CI, not reached], respectively; P = 0.405) with no statistical significance. The median OS was significantly longer in patients with non–CD74 than in those with CD74 (median OS, 28.07 months [95% CI, 23.93 to 32.1] vs not reached, respectively; P = 0.043). Multivariable analysis identified 1 significant factor associated with OS, brain metastasis before crizotinib treatment (P < 0.001). Conclusions: Our results indicate the better OS of crizotinib in patients with non–CD74 vs CD74. The ROS1 fusion partnerS might affect the efficacy of ALK-TKIs.