Abstract 1398P
Background
Clinical real-life data and PD pattern of EGFR mutant aNSCLC receiving systemic therapy after 1-2 gen TKI are current issues to be addressed.
Methods
This is an observational study at 3 Italian Centers enrolling EGFR mutant aNSCLC pts progressing after 1-2 gen TKI, between 2014 and 2018. Primary endpoint was to describe outcomes and PD patterns occurring at second line treatment after 1-2 gen TKI. Statistical analysis was performed by the Chi-square or Mann-Whitney test to correlate clinical features with EGFR T790M status, and by the Kaplan-Meier estimator to evaluate median progression free (mPFS2), median time to treatment failure (mTTF2) and overall survival (mOS). Log-rank test and Cox regression model were applied.
Results
At data cut-off (January 9, 2020), 89 pts with PD to first line TKI were included, 52 were T790M positive (P), 37 negative (N). All P received osimertinib, 22 out of 37 (59%) N received second line treatment (p < 0.001). Among these, 19 out of 22 (86%) received a platinum doublet, 3 out of 22 (14%) a mono-chemotherapy. mPFS2 was 11.6 months (m; 95%CI 8.2-14.9) in P, 5.9 m (95%CI 4.8-7.0) in N (p < 0.001), hazard ratio (HR) 0.32 (95%CI 0.19-0.57, p < 0.001). mTTF2 was 16.3 m in P (95%CI 12.3-20.4). mOS was 52.3 m (95%CI 37.1-67.5) in P, 22.9 m (95%CI 15.0-30.8) in N (p < 0.001; HR 0.36, 95%CI 0.21-0.60, p < 0.001). 32 (62%) P and 21 (95%) N progressed to second line treatment (PD2). A trend towards a lower number of (new) progressing sites, more frequent bone and liver PD and fewer distant nodes PD in P was shown, although without statistical significance. After PD2, 3 (9%) P continued osimertinib. Less P (19 of 32, 59%) received further systemic treatment compared to N (18 of 22, 82%), although without statistical significance. Median number of subsequent lines was 1 in both groups. 12 out of 19 P (63%) received a platinum doublet, 12 of 22 (54%) N docetaxel. At PD2, more N (7 of 22, 68%) underwent liquid or tissue rebiopsy, compared to P (9 of 32, 26%; p = 0.004).
Conclusions
These results suggest a specific PD pattern to second line osimertinib, though data on a larger series are needed for confirmation.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Istituto Oncologico Veneto - IRCCS.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.