Response to lorlatinib rechallenge in a case of ALK-rearranged metastatic NSCLC with a resistance mutation to second generation TKIs

Introduction: Several anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitors (TKIs) have been developed for the treatment of echinoderm microtubule-associated protein-like 4 (EML4)-ALK-rearranged non-small cell lung cancer (NSCLC), with the newer generation agents brigatinib, alectinib and lorlatinib showing prolonged responses. With the increasing number of target therapies available, the optimal sequence is yet to be defined, as resistance profiles may evolve over time and in response to sequential ALK inhibitors. Therefore, ALK-targeted strategies may be personalized based upon the presence of specific ALK resistance mutations. Methods: Here, we report on the case of a patient who has been treated with a sequence of three ALK TKIs after receiving diagnosis of ALK-rearranged metastatic NSCLC in 2015 and gained further benefit upon lorlatinib rechallenge after the acquisition of the G1202R resistance mutation to second generation TKIs. Results and conclusion: In this case, the first ALK resistance mutation detected after progression on first line TKI, the I1171N, is a common resistance mutation after alectinib and confers sensitivity to brigatinib, that the patient received afterwards with a long-term disease stability. The second ALK resistance mutation detected after a chemotherapy interval, the G1202R, is the most common resistance mutation after second generation ALK TKIs and has been associated with sensitivity to third generation TKIs, such as lorlatinib. This case of a patient with EML4-ALK-rearranged NSCLC shows that sequential treatment with next-generation ALK TKIs, including rechallenge, can induce profound remissions, even in heavily pretreated patients, and that ALK-targeted strategies may be personalized by considering the presence of distinct ALK resistance mutations.