ID #320 Overcoming ALK inhibitor resistance in ALK-fusion infant-type hemispheric glioma
Alessia Cais, Jana Nolle, Nina Hofmann, Marta Cook, Kenneth Chun-Ho Chan, Piyush Joshi, Lena Parzer, Lena M Kutscher, David T W Jones, Stefan M Pfister, Marc ZuckermannAbstract
Anaplastic lymphoma kinase (ALK)–driven infant-type hemispheric gliomas are commonly treated with tyrosine kinase inhibitors, such as lorlatinib, which often results in robust initial clinical responses. However, acquired treatment resistance frequently emerges, limiting long-term therapeutic efficacy. The aim of this study is to elucidate the mechanisms underlying lorlatinib resistance in ALK–driven tumor models and to rationalize combinatorial treatment strategies.
Through long-term drug exposure, we generated three independent, stable lorlatinib-resistant tumor cell cultures that continued to proliferate under treatment. Strikingly, all of these cells underwent less apoptosis upon lorlatinib exposure than DMSO-treated controls, indicating a tumor-supporting effect of ALK inhibition in resistant tumor cells. A similar phenotype was observed following treatment with an alternative ALK inhibitor (ALKi), crizotinib, suggesting a class-wide mechanism rather than a lorlatinib-specific effect. Ongoing genetic experiments aim to validate whether this phenomenon is dependent on ALK gene expression.
In parallel, we established lorlatinib-resistant tumors in vivo and performed bulk RNA sequencing on both in vitro– and in vivo–derived resistant models. Differential gene expression analysis revealed enrichment of pathways associated with apoptosis regulation, TGFβ–driven epithelial-to-mesenchymal transition, receptor tyrosine kinases (including MET, EGFR, and HER2/3), and PI3K–AKT–mTOR signaling. Functional drug testing demonstrated increased sensitivity of resistant cells to BCL-2/-XL inhibition compared to control cells. Evaluation of additional pathway-targeted inhibitors is ongoing, with the most promising candidates planned for preclinical testing in pediatric high-grade glioma mouse models.
Collectively, our results provide a comprehensive characterization of the acquired ALKi resistance phenotype in ALK–driven pediatric high-grade glioma and resolve potential therapeutic vulnerabilities, that, together, may inform improved treatment strategies in the future.