Abstract 151P
Background
ALK gene alterations are potent oncogenic drivers in NSCLC. Tyrosine kinase inhibitors targeting the ALK pathway are effective in treating ALK+ NSCLC. Around 4–5% of Asian and Caucasian patients with NSCLC have ALK+ tumors, but ALK rearrangement prevalence data for the MENA region are lacking.
Methods
In this non-interventional epidemiology study, histologically confirmed non-squamous NSCLC samples retained for <5 years in tissue banks at 6 centers in MENA were retrospectively analyzed for ALK rearrangement using the Ventana immunohistochemistry (IHC) method. Patient characteristics obtained from medical records were analyzed for any association with ALK rearrangement. Concordance between IHC and Vysis fluorescence in situ hybridization (FISH) ALK detection methods was assessed in a subset of samples.
Results
Overall 448 tissue samples were analyzed by IHC: 137 (30.6%) in Lebanon, 104 (23.2%) Saudi Arabia, 97 (21.7%) Egypt, 80 (17.9%) United Arab Emirates, 30 (6.7%) Morocco. Based on IHC, ALK-positivity prevalence was 8.7% (95% CI: 6.3–11.7), ALK-negativity was 91.3% (95% CI: 88.3–93.7; Table). Prevalence based on FISH (n=149) was 5.4% positivity and 81.8% negativity. Concordance between IHC and FISH (n=129) was 98.4% (95% CI: 94.2–99.8) for negative agreement and 100% (95% CI: 63.1–100) for positive agreement. Univariate analysis showed ALK rearrangement was significantly associated with epidermal growth factor (EGFR)-wild type status (p=0.03), but was not significantly associated with gender, race, smoking history, or histological subtype. Table: 151P
ALK rearrangement prevalence: ALK-IHC and ALK-FISH test
| Result | ALK-IHC | ALK-FISH | ||
| N | % | N | % | |
| Based on all results | ||||
| Total | 448 | 100 | 148 | 100 |
| Positive | 39 | 8.7 | 8 | 5.4 |
| Negative | 409 | 91.3 | 121 | 81.8 |
| Non-evaluable | 0 | 0 | 19 | 12.8 |
| Only patients with both tests evaluable* | ||||
| Total | 129 | 100 | 129 | 100 |
| Positive | 10 | 7.8 | 8 | 6.2 |
| Negative | 119 | 92.2 | 121 | 93.8 |
*Analysis of concordance in a subset of 3 centers in Saudi Arabia and Lebanon
Conclusions
Our findings suggest that ALK rearrangement prevalence is higher in MENA than elsewhere. High concordance was found between FISH and IHC methods. Except for EGFR wild-type status, no clinicopathological characteristics were associated with ALK+ NSCLC.
Clinical trial identification
Editorial acknowledgement
Medical writing support was provided by Claire Lavin, PhD, on behalf of CMC AFFINITY, McCann Health Medical Communications, and was funded by Pfizer.
Legal entity responsible for the study
Pfizer Inc.
Funding
Pfizer Inc.
Disclosure
A.R. Jazieh: Research grant/Funding (self): King Abdullah International Medical research Center; Travel/Accommodation/Expenses: BMS ; Travel/Accommodation/Expenses: AstraZeneca. H. Errihani: Advisory/Consultancy, Advisory Board: Roche; Advisory/Consultancy, Advisory Board: MSD; Advisory/Consultancy, Advisory Board: MERCK; Speaker Bureau/Expert testimony, Speaker: Novartis; Speaker Bureau/Expert testimony, Speaker: Amgen. F. Al Dayel: Full/Part-time employment, Consultant Pathologist, no conflict of interest: King Faisal Specialist Hospital and Research Centre. H. El Kadi: Full/Part-time employment: Pfizer. M. Magdy Abdallah: Full/Part-time employment: Pfizer. All other authors have declared no conflicts of interest.