Anaplastic lymphoma kinase rearrangements in non-small cell lung cancer in Jordan
Abstract Introduction/Objective ALK rearrangement is an important oncogenic driver in a substantial portion of non-small cell lung cancer (NSCLC) patients ranging from 2-7%. Treatment options such as ALK tyrosine kinase inhibitors (TKI) improve progression-free survival and overall survival. Candidates for such treatment are selected based on the identification of the ALK rearrangement. While fluorescence in situ hybridization (FISH) was considered the gold standard method, the availability of a robust FDA-approved companion diagnostic immunohistochemistry (IHC) assay has led to a paradigm shift in ALK testing. The purpose of this study is to determine the prevalence of ALK rearrangement in Jordanian NSCLC patients along with their clinicopathological characteristics and to compare the results of IHC and FISH methods for detecting ALK rearrangements. Methods/Case Report A retrospective study was conducted on 449 Jordanian King Hussein Cancer Center patients with NSCLC whose biopsy samples were tested for ALK rearrangement using FISH and or IHC (clone D5F3) in the period between 2018 and 2020. Results (if a Case Study enter NA) During the study period, the rate of ALK positivity by either IHC or FISH method was 4 percent (18 ALK positive cases out of 449 cases of non-small cell lung cancer). Seven cases were positive for both IHC and FISH, and nine cases were positive for IHC with no confirmation by FISH method; one case was ALK positive by IHC and negative by FISH with a significant response to ALK TKI; one case was IHC negative but FISH positive, with no ALK TKI therapy. The calculated sensitivity of ALK D5F3 immunostain compared to FISH results in the current study is 87.5% while the specificity is 96%. ALK positive patients were significantly younger than those with negative results (p-value=0.051), and women were three times more likely than men to have the rearrangement (p-value=0.013). Rearrangement was more likely to be found in nonsmokers/light or ex-smokers (p-value= 0.013). All patients had clinical stage IV or III disease at presentation with stage IV found in tow thirds of the patients. Conclusion ALK rearrangement is found in 4% of all NSCLC in Jordan. Patients are more likely to be younger, females and light or nonsmokers with an advanced stage disease at presentation. IHC is an acceptable alternative to FISH for ALK testing with reasonable sensitivity and specificity in addition to its advantages in terms of robustness, turnaround time and cost savings