ALK I1171N

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. 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.

V3 status is also associated with specific patterns of clinically important ALK resistance mutations. These tumor-intrinsic features may inform rational selection and optimization of first-line and consolidative therapy.

ALK inhibitors first-line crizotinib, second-line ceritinib, and alectinib are effective against NSCLC patients with these rearrangements. Based on the Y1278-C1097 H-bond and E1167-K1150 salt bridge interaction, I1171N strongly promotes the constitutively active kinase independent of ATP. This structural mechanism study will aid in understanding the oncogenic activity of ALK and the basis for improving the ALK inhibitors.

Legal entity responsible for the study Fondazione Policlinico Universitario A Gemelli – IRCCS. In post-lorlatinib NGS-assay, 2 pts had ALK-compound mutations, while 4 pts had newly off-target alterations (CDKN2A/B CDKN2B loss, NF1 deletion, DNMT3A/ARID1A/CHECK2 M+). Conclusions Implementation of longitudinal genomic assessment is required in order to provide an extensive overview of resistance mechanisms and clinical outcomes according to current ALK-inhibitors treatment sequences.

In Cohort 1 (n=21), 15 (71%) pts had progressed on alectinib, 5 (24%) on ceritinib and 1 (5%) on ensartinib. In Cohort 2 (n=18), pts had progressed on crizotinib followed by alectinib (n=9, 50%), ceritinib (n=4, 22%) or brigatinib (n=3, 17%); 2 (11%) pts progressed on crizotinib, then ceritinib followed by alectinib...Of 5 pts with ALK resistance mutations (I1171N, V1180L, L1196M, G1202R, and E1210K) who subsequently received lorlatinib, repeat ctDNA NGS after 2 months demonstrated clearance of ALK resistance mutation(s) in 4/5 (80%) pts (i.e. undetectable on repeat testing)... Resistance mechanisms to ALK inhibitors are heterogenous, including both ALK dependent and independent pathways. DDR and cell cycle gene alterations were commonly detected and may represent previously unreported acquired resistance alterations. Comprehensive ctDNA NGS analysis at progression may help detect novel resistance alterations in patients on ALK inhibitors.

This treatment may provide a new therapeutic strategy for ALK TKIs resistant patients, especially in position 1171 of ALK exon20.

Of these, 52 received first-line alectinib treatment (1L) and 56 received alectinib after crizotinib resistance (2L). Also, NF2-mutant patients only had a median PFS of 4 months, significantly poorer than those without (HR 11.1, 95CI 2.17-50; p<0.001). Conclusions By analyzing different mutational profiles of ALK-rearranged patients after alectinib treatment, we proposed MET and NF2 as putative mechanisms that conferred resistance to early resistance of first-line alectinib, which shone light on future tailored treatment for ALK-positive NSCLCs.

Results Of the 133 pts who progressed on alectinib, with or without prior crizotinib or chemotherapy, 131 had evaluable baseline plasma data. The presence of secondary ALK mutations at baseline was associated with a similar ORR (34.5%) and median DoR (5.6 months) and shorter median PFS (3.7 months), with response/clinical benefit observed in pts with G1202R, L1196M, and I1171N ALK secondary mutations. Table: 1009P Brigatinib efficacy parameters a according to baseline ALK mutation status conclusions Brigatinib showed clinically meaningful activity in pts with alectinib-resistant ALK+ NSCLC with or without a detectable ALK fusion and/or secondary mutations.

Structural analysis revealed increased potency against compound mutations through improved inhibition of either G1202R or I1171N/S/T mutant kinases. Overall, we propose a classification of heterogenous ALK compound mutations enabling the development of distinct therapeutic strategies for precision targeting following sequential tyrosine kinase inhibitors.

In contrast to wild conformation, the mutant conformations exhibited a reduced node degree in their residue interaction networks. Collectively, our findings provide deeper insights into the deleterious effects of I1171N + F1174I and I1171N + L1198H ALK compound mutations, which may contribute to NSCLC pathogenesis.Communicated by Ramaswamy H. Sarma.

She was treated with alectinib and acquired ALK p.I1171N and p.V1180L mutations...After sequential lines of ceritinib and chemotherapy, lorlatinib was chosen as the fourth-line therapy and maintained control for 6 months...To the best of our knowledge, this case is the first to provide clinical evidence of antitumor activity of olaparib plus ALK TKI in ALK-positive, gBRCA-mutated metastatic NSCLC. Together with previous reports in EGFR-positive or driver-negative patients, our finding warrants further studies on PARP inhibition in BRCA1/2-mutated NSCLC.