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MA 07 - ALK, ROS and HER2 (ID 673)
- Event: WCLC 2017
- Type: Mini Oral
- Track: Advanced NSCLC
- Presentations: 1
MA 07.07 - Clinical Outcomes and ALK Resistance Mutations in ALK+ Non-Small Cell Lung Cancer According to EML4-ALK Variant (ID 8255)
15:45 - 17:30 | Author(s): S. Yoda
Advanced ALK+ non-small cell lung cancers (NSCLCs) are effectively treated with ALK tyrosine kinase inhibitors (TKIs). However, clinical outcomes among patients treated with ALK TKIs vary, and the clinical benefit of TKI therapy is limited due to acquired resistance. To date, emerging data suggest that the specific EML4-ALK variant may impact clinical outcome, but whether variant is associated with mechanisms of TKI resistance is unknown.
We identified 108 advanced ALK+ NSCLC cases with known ALK fusion variants. Progression-free survival (PFS) on ALK TKIs and resistance mechanisms were retrospectively evaluated according to ALK variant.
The 108 ALK+ cases consisted of: 42 (39%) EML4-ALK v1 (E13;A20), 8 (7.4%) v2 (E20;A20), 45 (41.7%) v3 (E6;A20), 3 (2.8%) v5 (E2;A20), 4 (3.7%) v5’ (E18;A20), 1 (0.9%) v7 (E14;A20), and 5 (4.6%) non-EML4-ALK variants. Given the small numbers of non-v1/v3 cases, v1 and v3 cases were selected for further analysis. Among the 21 v1 and 25 v3 cases treated with first-line crizotinib, there was no significant difference in PFS (HR = 0.81 [95% CI, 0.42-1.57], p = 0.526). Similarly, there was no difference in PFS on second-generation ALK TKIs among 35 v1 and 35 v3 patients who received ceritinib, alectinib, or brigatinib following first- or later-line crizotinib (HR = 1.32 [95% CI, 0.77-2.26], p = 0.308). Interestingly, among 12 v1 and 17 v3 patients who received the third-generation TKI lorlatinib after failure of a second-generation TKI, v3 was associated with significantly longer PFS than v1 (HR = 0.250 [95% CI, 0.09-0.72], p = 0.006). From our cohort, we identified 11 v3 and 14 v1 post-crizotinib biopsies. No difference was noted in the presence of ALK resistance mutations (27% and 21%, respectively; p = 1.000). In contrast, among 30 v3 and 18 v1 post-second generation TKI biopsies, ALK resistance mutations were more common among v3 vs v1 cases (66% vs 44%, respectively; p = 0.147). Furthermore, the ALK G1202R solvent front mutation occurred more frequently in v3 vs v1 (47% vs 0%, respectively; p = 0.001).
Our findings suggest that EML4-ALK variants 1 and 3 may not be associated with significantly different PFS outcomes on crizotinib or second-generation ALK TKIs. However, ALK resistance mutations, particularly G1202R, occur more frequently in v3 vs v1 post–second generation TKI. Patients with this variant may therefore derive particular benefit from third-generation, pan-inhibitory ALK TKIs. Larger, prospective studies will be needed to confirm these findings.
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