Feasibility of continuing crizotinib therapy after RECIST-PD in advanced non-small cell lung cancer patients with ALK/ROS-1 mutations

Objectives: To study whether ongoing clinical benefits of continuing anaplastic lymphoma kinase (ALK) and c-ros oncogene 1 (ROS1) inhibition are achieved by crizotinib treatment post progressive disease (PD) in advanced non-small cell lung cancer (NSCLC) patients harboring ALK/ROS1 mutations. Materials and methods: Demographic and clinicopathologic parameters were collected from 38 patients who continued crizotinib therapy beyond Response Evaluation Criteria in Solid Tumors (RECIST)-defined PD and analyzed. After adjusting for potential confounding factors, factors influencing the time from RECIST-PD to crizotinib discontinuation (progress-free survival 2, PFS2) were analyzed. Results: The median time from first dose treatment to RECIST-PD (PFS1) was 9.6 months (95% CI 5.6-13.6 months). The estimated median PFS2 was 5.9 months (95% CI 0.1-11.7 months). Six- and twelve-month crizotinib treatment probabilities after initial PD were 42.1% (95% CI 25.7-58.6%) and 21.1% (95% CI 7.5-34.6%), respectively. Patients who demonstrated RECIST-PD due to new lesions had a longer median PFS2 compared to patients who were attested to enlargement of original lesions (10.0 versus 2.4 months, p = 0.009). The median PFS2 was numerically longer among patients who received local therapy compared to those who did not receive local therapy, however the difference was not significant (9.9 versus 4.2 months, p = 0.094). Multivariable Cox regression analysis showed that only the progression pattern [new lesions versus enlargement of original lesions, HR = 0.329 (95% CI 0.138-0.782), p = 0.012] remained an independent prognostic factor of PFS2. Conclusion: Continuation of crizotinib therapy after RECIST-PD in Chinese NSCLC patients with positive ALK/ROS1 mutations is feasible in clinical practice.