Off-label targeted therapy (TT) use in recurrent/metastatic NSCLC.

Abstract

e18688 Background: Comprehensive genomic profiling (CGP) is an established diagnostic approach to select patients for TT. As CGP gains wide adoption, an increasing number of patients are found to harbor driver mutations for which no approved TT is available. This is often addressed through use of matched TKI and mAb approved for other mutations or anatomic sites. In this work, we examined the clinical efficacy of off-label TT in R/M NSCLC. Methods: Using a de-identified NSCLC clinico-genomic database (CGDB), we identified 6590 NSCLC patients who underwent Foundation Medicine CGP, of whom 17.8% harbored an actionable genomic alteration (GA) for which an FDA-approved TT was available and 2% (133) whose GA (MET ex-14, uncommon EGFRm, EGFR ex20ins, HER2 amp/mut, RET fusion, BRAF class 2/3) lacked an FDA-approved TT (62 in 1L and 71 in ≥2L ) who received matched off-label TT. ESMO Scale for Clinical Actionability (ESCAT) was used to grade levels of evidence. For patients who progressed on initial chemotherapy (range 2 – 9 lines, median 3), we calculated clinical efficacy using the ratio of real world PFS on targeted therapy (rw-PFS2) to rw-PFS on the last prior line of therapy (rw-PFS1) and used a cut-off of PFS2/PFS1 > 1.3 to determine off-label drug efficacy. Results: Of the 133 patients reviewed, 72 were classified as ESCAT level IB (uncommon EGFRm, MET-ex14), 45 IIB (HER2m/amp, EGFR ex-20ins), 7 IC (RET fusions). PFS varied significantly by mutation and line of therapy (table 1) with uncommon EGFRm+ and MET-ex14 exhibiting best response while EGFR ex20 ins, BRAF class 2/3 and HER2 amp fared significantly worse. 55.8% of the patients (39 of 71) reached a PFS2/PFS1 ratio > 1.3 (two-sided 95% CI, 45.3 % – 68.7 %), ranging from 93% in uncommon EGFRm+ down to 20% in HER2 amp and 44% in ex20ins. Conclusions: We provide real-world evidence to assess off-label TT in NSCLC. Clinical benefit derived from off-label TT is unevenly distributed across various mutations with most survival advantage accruing to specific mutations (MET-ex14 and uncommon EGFRm) at the expense of others (HER2 amp). Survival advantage was highly influenced by two factors: A) the timing of CGP with the earlier recipients of genomic profiling achieving better outcome, B) the identity of the driver mutation, highlighting the role of clinical actionability tier system to define level of evidence supporting such intervention.[Table: see text]