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MA 07 - ALK, ROS and HER2 (ID 673)
- Event: WCLC 2017
- Type: Mini Oral
- Track: Advanced NSCLC
- Presentations: 1
MA 07.01 - Patients with ALK IHC-Positive/FISH-Negative NSCLC Benefit from ALK TKI Treatment: Response Data from the Global ALEX Trial (ID 9008)
15:45 - 17:30 | Author(s): C. Williams
Patients with ALK-positive NSCLC have seen significant advances and increased options in ALK targeted therapies recently, and therefore rely on high quality, robust ALK status testing. Fluorescence in-situ hybridization (FISH) and immunohistochemistry (IHC) are the most common methods to determine ALK status for ALK tyrosine kinase inhibitor (TKI) treatment. However, availability of clinical outcome data from randomized trials linked directly to specific methods is limited. The ALEX trial (BO28984, NCT02075840) provides a unique dataset to assess ALK IHC- and FISH-based assays regarding clinical outcome for alectinib and crizotinib, particularly for the subset of patients with IHC-positive/FISH-negative NSCLC.
The VENTANA ALK (D5F3) CDx Assay (ALK IHC) performed in central laboratories was used as an enrollment assay for the selection of patients with ALK-positive NSCLC for inclusion in the ALEX trial. Additional samples from these patients were retrospectively tested in central laboratories with the Vysis ALK Break Apart FISH Probe Kit (ALK FISH).
Overall, 303 patients all with ALK IHC-positive NSCLC were randomized in the ALEX trial, of those 242 patients also had a valid ALK FISH result, with 203 patients having ALK FISH-positive disease and 39 patients having ALK FISH-negative disease (alectinib, n=21; crizotinib, n=18). For 61 of 303 (20.1%) patients with an ALK IHC-positive result, a valid ALK FISH result could not be obtained due to the test leading to an uninformative FISH result (10.9%), or not having adequate/no tissue available (9.2%). Ventana IHC staining success rates were higher than for Vysis FISH testing for the ALEX samples. Exploratory analysis of investigator-assessed progression-free survival (PFS) in patients with a FISH-positive result (HR 0.40, 95% CI 0.27–0.61; p<0.0001; median not reached [alectinib] versus 12.7 months [crizotinib]) was consistent with the primary endpoint analysis in the Ventana ALK IHC-positive population. Patient outcome data show that 28% of central ALK IHC-positive/ALK FISH-negative samples were from patients who responded to ALK TKI treatment (complete response or partial response) and 33% had stable disease according to investigator assessment.
This analysis shows that ALK IHC is a robust testing approach, which may identify more patients with a valid ALK testing result who benefit from ALK TKI treatment than ALK FISH testing. While PFS of patients with ALK FISH-positive NSCLC was similar to that of patients with ALK IHC-positive NSCLC, the analysis also revealed that the majority of patients with ALK IHC-positive/ALK FISH-negative NSCLC may derive clinical benefit from ALK TKI treatment.
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