Drug resistance inevitably limits the efficacy of all targeted therapies including tyrosine kinase inhibitors (TKIs). Understanding the biological underpinnings of TKI resistance is key to the ...successful development of future therapeutic strategies. Traditionally, mechanisms of TKI resistance have been viewed under a dichotomous lens. Tumor cells are TKI-sensitive or TKI-refractory, exhibit intrinsic or acquired resistance, and accumulate alterations within or outside the target to promote their survival. Such classifications facilitate our comprehension of an otherwise complex biology, but are likely an oversimplification. Recent studies underscore the multifaceted, genetically heterogeneous nature of TKI resistance, which evolves dynamically with changes in therapy. In this Review, we provide a broad framework for understanding the diverse mechanisms of resistance at play in oncogene-driven lung cancers.
Dysfunction in prosocial interactions is a core symptom of autism spectrum disorder. However, the neural mechanisms that underlie sociability are poorly understood, limiting the rational development ...of therapies to treat social deficits. Here we show in mice that bidirectional modulation of the release of serotonin (5-HT) from dorsal raphe neurons in the nucleus accumbens bidirectionally modifies sociability. In a mouse model of a common genetic cause of autism spectrum disorder-a copy number variation on chromosome 16p11.2-genetic deletion of the syntenic region from 5-HT neurons induces deficits in social behaviour and decreases dorsal raphe 5-HT neuronal activity. These sociability deficits can be rescued by optogenetic activation of dorsal raphe 5-HT neurons, an effect requiring and mimicked by activation of 5-HT1b receptors in the nucleus accumbens. These results demonstrate an unexpected role for 5-HT action in the nucleus accumbens in social behaviours, and suggest that targeting this mechanism may prove therapeutically beneficial.
The cornerstone of treatment for advanced ALK-positive lung cancer is sequential therapy with increasingly potent and selective ALK inhibitors. The third-generation ALK inhibitor lorlatinib has ...demonstrated clinical activity in patients who failed previous ALK inhibitors. To define the spectrum of
mutations that confer lorlatinib resistance, we performed accelerated mutagenesis screening of Ba/F3 cells expressing EML4-ALK. Under comparable conditions,
-ethyl-
-nitrosourea (ENU) mutagenesis generated numerous crizotinib-resistant but no lorlatinib-resistant clones harboring single
mutations. In similar screens with EML4-ALK containing single
resistance mutations, numerous lorlatinib-resistant clones emerged harboring compound
mutations. To determine the clinical relevance of these mutations, we analyzed repeat biopsies from lorlatinib-resistant patients. Seven of 20 samples (35%) harbored compound
mutations, including two identified in the ENU screen. Whole-exome sequencing in three cases confirmed the stepwise accumulation of
mutations during sequential treatment. These results suggest that sequential ALK inhibitors can foster the emergence of compound
mutations, identification of which is critical to informing drug design and developing effective therapeutic strategies.
Treatment with sequential first-, second-, and third-generation ALK inhibitors can select for compound
mutations that confer high-level resistance to ALK-targeted therapies. A more efficacious long-term strategy may be up-front treatment with a third-generation ALK inhibitor to prevent the emergence of on-target resistance.
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Intracranial metastases are a common cause of morbidity and mortality in patients with advanced NSCLC, and are frequently managed with radiation therapy (RT). The safety of cranial RT in the setting ...of treatment with immune checkpoint inhibitors (ICIs) has not been established.
We identified patients with advanced NSCLC with brain metastases who received cranial RT and were treated with or without programmed cell death 1/programmed death ligand 1 inhibitors between August 2013 and September 2016. RT-related adverse events (AEs) were retrospectively evaluated and analyzed according to ICI treatment status, cranial RT type, and timing of RT with respect to ICI.
Of 163 patients, 50 (31%) received ICIs, whereas 113 (69%) were ICI naive. Overall, 94 (58%), 28 (17%), and 101 (62%) patients received stereotactic radiosurgery, partial brain irradiation, and/or whole brain RT, respectively. Fifty percent of patients received more than one radiation course. We observed no significant difference in rates of all-grade AEs and grade 3 or higher AEs between the ICI-naive and ICI-treated patients across different cranial RT types (grade ≥3 AEs in 8% of ICI-naive patients versus in 9% of ICI-treated patients for stereotactic radiosurgery p = 1.00 and in 8% of ICI-naive patients versus in 10% of ICI-treated patients for whole brain RT p = 0.71). Additionally, there was no difference in AE rates on the basis of timing of ICI administration with respect to RT.
Treatment with an ICI and cranial RT was not associated with a significant increase in RT-related AEs, suggesting that use of programmed cell death 1/programmed death ligand 1 inhibitors in patients receiving cranial RT may have an acceptable safety profile. Nonetheless, additional studies are needed to validate this approach.
Two RET inhibitors, selpercatinib and pralsetinib, recently received approval for the treatment of advanced RET fusion-positive lung cancer. Acquired resistance to these inhibitors will be a major ...challenge. We have shown that resistance can emerge due to recurrent RET kinase domain mutations and, in most cases, due to RET-independent mechanisms.
STK11 and KEAP1 mutations (STK11 mutant STK11MUT and KEAP1MUT) are among the most often mutated genes in lung adenocarcinoma (LUAD). Although STK11MUT has been associated with resistance to ...programmed death-(ligand)1 (PD-L1) inhibition in KRASMUT LUAD, its impact on immunotherapy efficacy in KRAS wild-type (KRASWT) LUAD is currently unknown. Whether KEAP1MUT differentially affects outcomes to PD-(L)1 inhibition in KRASMUT and KRASWT LUAD is also unknown.
Clinicopathologic and genomic data were collected from September 2013 to September 2020 from patients with advanced LUAD at the Dana-Farber Cancer Institute/Massachusetts General Hospital cohort and the Memorial Sloan Kettering Cancer Center/MD Anderson Cancer Center cohort. Clinical outcomes to PD-(L)1 inhibition were analyzed according to KRAS, STK11, and KEAP1 mutation status in two independent cohorts. The Cancer Genome Atlas transcriptomic data were interrogated to identify differences in tumor gene expression and tumor immune cell subsets, respectively, according to KRAS/STK11 and KRAS/KEAP1 comutation status.
In the combined cohort (Dana-Farber Cancer Institute/Massachusetts General Hospital + Memorial Sloan Kettering Cancer Center/MD Anderson Cancer Center) of 1261 patients (median age = 61 y range: 22–92, 708 women 56.1%, 1065 smokers 84.4%), KRAS mutations were detected in 536 cases (42.5%), and deleterious STK11 and KEAP1 mutations were found in 20.6% (260 of 1261) and 19.2% (231 of 1202) of assessable cases, respectively. In each independent cohort and in the combined cohort, STK11 and KEAP1 mutations were associated with significantly worse progression-free (STK11 hazard ratio HR = 2.04, p < 0.0001; KEAP1 HR = 2.05, p < 0.0001) and overall (STK11 HR = 2.09, p < 0.0001; KEAP1 HR = 2.24, p < 0.0001) survival to immunotherapy uniquely among KRASMUT but not KRASWT LUADs. Gene expression ontology and immune cell enrichment analyses revealed that the presence of STK11 or KEAP1 mutations results in distinct immunophenotypes in KRASMUT, but not in KRASWT, lung cancers.
STK11 and KEAP1 mutations confer worse outcomes to immunotherapy among patients with KRASMUT but not among KRASWT LUAD. Tumors harboring concurrent KRAS/STK11 and KRAS/KEAP1 mutations display distinct immune profiles in terms of gene expression and immune cell infiltration.
We present a cohort of 41 patients with osimertinib resistance biopsies, including 2 with an acquired
fusion. Although
fusions have been identified in resistant
-mutant non-small cell lung cancer ...(NSCLC), their role in acquired resistance to EGFR inhibitors is not well described. To assess the biological implications of
fusions in an
-mutant cancer, we expressed CCDC6-RET in PC9 (
del19) and MGH134 (
L858R/T790M) cells and found that CCDC6-RET was sufficient to confer resistance to EGFR tyrosine kinase inhibitors (TKI). The selective RET inhibitors BLU-667 and cabozantinib resensitized CCDC6-RET-expressing cells to EGFR inhibition. Finally, we treated 2 patients with
-mutant NSCLC and
-mediated resistance with osimertinib and BLU-667. The combination was well tolerated and led to rapid radiographic response in both patients. This study provides proof of concept that
fusions can mediate acquired resistance to EGFR TKIs and that combined EGFR and RET inhibition with osimertinib/BLU-667 may be a well-tolerated and effective treatment strategy for such patients. SIGNIFICANCE: The role of
fusions in resistant
-mutant cancers is unknown. We report that
fusions mediate resistance to EGFR inhibitors and demonstrate that this bypass track can be effectively targeted with a selective RET inhibitor (BLU-667) in the clinic.
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Entrectinib potently inhibits tropomyosin receptor kinases (TRKAs)/B/C and ROS1, and previously induced deep objective response rate (ORR) 57.4% and durable median duration of response (DoR) 10.4 ...months responses in adults with NTRK fusion-positive solid tumors from three phase I/II trials. This article expands prior reports with additional patients and longer follow-up.
Patients with locally advanced/metastatic NTRK fusion-positive solid tumors and ≥12 months' follow-up were included. Primary endpoints were ORR and DoR by blinded independent central review (BICR); secondary endpoints included progression-free survival (PFS), intracranial efficacy, and safety. The safety-evaluable populations included all patients who had received ≥1 entrectinib dose.
At clinical cut-off (August 31, 2020), the efficacy-evaluable population comprised 121 adults with 14 tumor types and ≥30 histologies. Median follow-up was 25.8 months; 61.2% of patients had a complete (n = 19) or partial response (n = 55). Median DoR was 20.0 months 95% confidence interval (CI), 13.0-38.2; median PFS was 13.8 months (95% CI, 10.1-19.9). In 11 patients with BICR-assessed measurable central nervous system (CNS) disease, intracranial ORR was 63.6% (95% CI, 30.8-89.1) and median intracranial DoR was 22.1 (95% CI, 7.4-not estimable) months. The safety profile of entrectinib in adults and pediatric patients was aligned with previous reports. Most treatment-related adverse events (TRAEs) were grade 1/2 and manageable/reversible with dose modifications. TRAE-related discontinuations occurred in 8.3% of patients.
With additional clinical experience, entrectinib continues to demonstrate durable systemic and intracranial responses and can address the unmet need of a CNS-active treatment in patients with NTRK fusion-positive solid tumors.
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