EML4-ALK variant 3

Here, using two separate approaches to displace V3 from microtubules and a variety of in vitro assays, we show that microtubule association of EML4-ALK V3 is required for both V3 phenotypes, as removal of the oncogenic fusion protein from microtubules led to the dissociation of the V3-NEK9-NEK7 complex and the reversal of both phenotypic changes. Overall, we propose that targeting the interaction between EML4-ALK V3 and microtubules might offer a novel therapeutic option, independent of ALK activity, for V3+ NSCLC patients with acquired resistance to ALK inhibitors.

In addition, proteomic analysis of brigatinib-treated cells revealed the upregulation of SRC kinase, a protein frequently activated in cancer...Our study demonstrates that the simultaneous inhibition of ALK and SRC can potentially overcome resistance mechanisms and enhance clinical outcomes in ALK-positive lung cancer patients. ONE SENTENCE SUMMARY: Co-targeting ALK and SRC enhances ALK inhibitor response in lung cancer by affecting the proteomic profile, offering hope for overcoming resistance and improving clinical outcomes.

Currently, a fourth-generation (4G) ALK TKI, NVL-655, is being developed to attack some of the unmet needs such as compound resistance mutations in cis...Potentially, in the shifting landscape where lorlatinib should be the first-line ALK TKI of choice based on the CROWN trial, the central β-sheet #6 (Cβ6) mutation ALK L1256F will be the potential acquired resistance mutation to lorlatinib which may be resistant to current ALK TKIs. Here we opine on what additional capacities a putative fifth-generation (5G) ALK TKI will need to possess if it can be achieved in one single molecule. We propose randomized trial schemas targeting some of the intrinsic resistance mechanisms that will lead to approval of a prototypic fifth-generation (5G) ALK TKI and actually be beneficial to ALK+ NSCLC patients rather than just design a positive pivotal superiority trial for the sole purpose of drug approval.

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.

These findings highlight the complexity of drug selection when treating patients harboring resistance mutations and suggest that the F1174S mutation in EML4-ALK variant 1 is likely not a potent oncogenic driver. Additional oncogenic driver or other resistance mechanisms should be considered in the case of EML4-ALK variant 1 with F1174S mutation.

PC-9_v3a-gef and PC-9_v3b-gef cells were resistant to gefitinib and ALK inhibitors alone, but ALK inhibitors enhanced gefitinib-induced cytotoxicity. Furthermore, combination treatment with osimertinib and ceritinib caused a decrease in liver tumor size of the patient with liver metastases. Our data suggest that combination treatment with EGFR and ALK inhibitors can be a therapeutic strategy for treating NSCLC with concomitant EGFR mutation and EML4-ALK rearrangement.

In ALTA-2, brigatinib demonstrated limited activity in patients with ALK+ NSCLC post-ceritinib or post-alectinib therapy. Median PFS was longer with brigatinib in patients without baseline detectable plasma ALK fusion.

We provide a characterization of four novel EML4-ALK-positive NSCLC cell lines, highlighting genomic heterogeneity and differential responses to ALK TKI treatment. The RNA-Seq characterization of ALK-positive NSCLC CUTO8, CUTO9, CUTO29 and YU1077 cell lines reported here, has been compiled in an interactive ShinyApp resource for public data exploration (https://ccgg.ugent.be/shiny/nsclc_rrm2_2022/).

These patient-derived cell lines exhibit differential sensitivity to ALK TKIs, such as lorlatinib, brigatinib and alectinib, with EML4-ALK variant 3 containing cell lines exhibiting an increased sensitivity to lorlatinib and brigatinib as compared to alectinib. In conclusion, we have identified and characterized three novel EML4-ALK-positive NSCLC cell lines and identified RRM2 as a novel dependency gene that is a promising target for synergistic drug combinations with ALK TKIs in ALK-positive NSCLC.

Finally, we demonstrate that cells expressing EML4-ALK V3 have increased sensitivity to microtubule poisons that interfere with mitotic spindle assembly, whereas combination treatment with paclitaxel and clinically approved ALK inhibitors leads to a synergistic response in terms of reduced survival of H2228 cells. This study suggests that combining the microtubule poison, paclitaxel, with targeted ALK inhibitors may provide an effective new treatment option for patients with NSCLC with tumors that express the EML4-ALK V3 oncogenic fusion.

Here, we report, for the first time, a novel, sequentially-evolved EML4-ALK variant 3 G1202R/S1206Y double mutation in cis detected in a patient with ALK-positive NSCLC after disease progression on sequential crizotinib, alectinib, and then lorlatinib. Three-dimensional computer modeling of this double mutation and other G1202R-based double mutations with lorlatinib (ALK G1202R/L1196M, ALK G1202R/F1174C, ALK G1202R/l1198F, ALK G1202R/G1269A) were provided to reveal how these double mutations may confer resistance to lorlatinib through diverse steric hindrances in the ALK kinase domain. In addition, we performed a comprehensive literature review on published acquired double or triple ALK mutations that are resistant to lorlatinib from both patient samples and in vitro mutagenesis experiments.

Our data suggest that the aberrant expression of EML4-ALK leads to JAK2-STAT signaling pathway activation, which is essential for the development of non-small cell lung cancer.