Modulation of central synapse remodeling after remote peripheral injuries by the CCL2-CCR2 axis and microglia.

Microglia-mediated synaptic plasticity after CNS injury varies depending on injury severity, but the mechanisms that adjust synaptic plasticity according to injury differences are largely unknown. This study investigates differential actions of microglia on essential spinal motor synaptic circuits following different kinds of nerve injuries. Following nerve transection, microglia and C-C chemokine receptor type 2 signaling permanently remove Ia axons and synapses from the ventral horn, degrading proprioceptive feedback during motor actions and abolishing stretch reflexes. However, Ia synapses and reflexes recover after milder injuries (nerve crush). These different outcomes are related to the length of microglia activation, being longer after nerve cuts, with slower motor-axon regeneration and extended expression of colony-stimulating factor type 1 in injured motoneurons. Prolonged microglia activation induces CCL2 expression, and Ia synapses recover after ccl2 is deleted from microglia. Thus, microglia Ia synapse removal requires the induction of specific microglia phenotypes modulated by nerve regeneration efficiencies. However, synapse preservation was not sufficient to restore the stretch-reflex function.

Medication Prescribing Errors on a Surgery Service - Addressing the Gap with a Curriculum for Surgery Residents: A Prospective Observational Study.

OBJECTIVES: Educational interventions with proven effectiveness to reduce medication prescribing errors are currently lacking. Our objective was to implement and assess the effectiveness of a curriculum to reduce medication prescribing errors on a surgery service. METHODS: This was a prospective observational cohort study at a Canadian academic hospital without an electronic order entry system. A pharmacist-led medication prescribing curriculum for surgery residents was developed and implemented over 2 days (2 h/day) in July 2019. Thirteen (76%) out of 17 surgery residents contributed pre-implementation data, while 13 (81%) out of 16 surgery residents contributed post-implementation data. Medication prescribing errors were tracked for 12 months pre-implementation and 6 months post-implementation. Errors were classified as prescription writing (PW) or decision making (DM). RESULTS: There were a total of 1050 medication prescribing errors made in the pre-implementation period with 615 (59%) PW errors and 435 (41%) DM. There were a mean of 87.5 (SD = 14.6) total medication prescribing errors per month in the pre-implementation period with 51.3 (11.9) PW and 36.3 (6.0) DM errors. There were a total of 472 medication prescribing errors made in the post-implementation period with 260 (55%) PW and 212 (45%) DM errors. There were a mean of 78.7 (10.3) total medication prescribing errors per month in the post-implementation period with 43.3 (9.5) PW and 35.3 (4.2) DM errors. In the first quarter of the academic year, there were significantly fewer mean total errors per month post-implementation versus pre-implementation (77.7(12.7) versus 107.3(8.1); P = .035), with significantly fewer PW errors per month (40.7(13.2) versus 68.7(9.3); P = .046) and no difference in DM errors per month (37.0(2.0) versus 38.7(5.7);P = .671). There were no differences noted in the second quarter of the academic year. CONCLUSION: Medication prescribing errors occurred from PW and DM. Medication prescribing curriculum decreased PW errors; however, a continued education program is warranted as the effect diminished over time.

Comprehensive Review of ROS1 Tyrosine Kinase Inhibitors-Classified by Structural Designs and Mutation Spectrum (Solvent Front Mutation [G2032R] and Central ß-Sheet 6 [Cß6] Mutation [L2086F]).

Despite ROS1 fusion-positive NSCLC accounting for approximately 1% to 2% of NSCLC, there is a long list of ROS1 tyrosine kinase inhibitors (TKIs) being developed in addition to three approved ROS1 TKIs, crizotinib, entrectinib and repotrectinib. Here, we categorized ROS1 TKIs by their structures (cyclic versus noncyclic) and inhibitory abilities (active against solvent front mutation G2032R or central ß-sheet #6 [Cß6] mutation L2086F) and summarized their reported clinical activity in order to provide a dashboard on how to use these ROS1 TKIs in various clinical situations. In addition, the less known Cß6 mutation ROS1 L2086F confer resistances to next-generation ROS1 TKIs (repotrectinib, taletrectinib, and potentially NVL-520) that can be overcome by cabozantinib as documented in published patient reports and potentially by certain L-shaped type I ROS1 TKIs including ceritinib and gilteritinib, which is approved as a FLT3 inhibitor for relapsed refractory FLT3+ acute myeloid leukemia but have published preclinical activites against ROS1 (and ALK). Future clinical trials should investigate cabozantinib and gilteritinib to repurpose them as ROS1 TKIs that can target ROS1 L2086F Cß6 mutation.

Pan-tumor survey of ROS1 fusions detected by next-generation RNA and whole transcriptome sequencing.

BACKGROUND: Two ROS1 tyrosine kinase inhibitors have been approved for ROS1 fusion positive (ROS1+) non-small cell lung cancer (NSCLC) tumors. We performed a pan-tumor analysis of the incidence of ROS1 fusions to assess if more ROS1+ patients who could benefit from ROS1 TKIs could be identified. METHODS: A retrospective analysis of ROS1 positive solid malignancies identified by targeted RNA sequencing and whole transcriptome sequencing of clinical tumor samples performed at Caris Life Science (Phoenix, AZ). RESULTS: A total of 259 ROS1+ solid malignancies were identified from approximately 175,350 tumors that underwent next-generation sequencing (12% from targeted RNA sequencing [Archer]; 88% from whole transcriptome sequencing). ROS1+ NSCLC constituted 78.8% of the ROS1+ solid malignancies, follow by glioblastoma (GBM) (6.9%), and breast cancer (2.7%). The frequency of ROS1 fusion was approximately 0.47% among NSCLC, 0.29% for GBM, 0.04% of breast cancer. The mean tumor mutation burden for all ROS1+ tumors was 4.8 mutations/megabase. The distribution of PD-L1 (22C3) expression among all ROS1+ malignancies were 0% (18.6%), 1%-49% (29.4%), and ≥ 50% (60.3%) [for NSCLC: 0% (17.8%); 1-49% (27.7%); ≥ 50% (53.9%). The most common genetic co-alterations of ROS1+ NSCLC were TP53 (29.1%), SETD2 (7.3%), ARIAD1A (6.3%), and U2AF1 (5.6%). CONCLUSIONS: ROS1+ NSCLC tumors constituted the majority of ROS1+ solid malignancies with four major fusion partners. Given that > 20% of ROS1+ solid tumors may benefit from ROS1 TKIs treatment, comprehensive genomic profiling should be performed on all solid tumors.

Lorlatinib Tolerability and Association With Clinical Outcomes in Patients With Advanced ALK- or ROS1-Rearranged NSCLC: A Brief Report.

Introduction: Treatment with lorlatinib for patients with advanced ALK- and ROS1-rearranged NSCLC (ALK+ and ROS1+ NSCLC) is associated with a unique set of adverse events (AEs) often requiring dose reduction. However, the impact of dose reductions on outcomes remains unclear and is mainly limited to analyses from prospective studies of lorlatinib in the first-line setting. Methods: We reviewed the course of 144 patients with advanced ALK- or ROS1-rearranged NSCLC treated with lorlatinib in the second-line or later setting to assess the frequency of dose reductions resulting from treatment-related AEs (TRAEs) and the association between dose reductions and progression-free survival (PFS) and overall survival (OS). Results: A total of 58 patients (40%) had TRAE-related dose reductions, most (59%) owing to neurocognitive AEs or neuropathy. Among all patients, the median PFS was 8.1 months (95% confidence interval [CI]: 6.4-11.8); the median OS was 20.7 months (95% CI: 16.3-30.5). Among patients who were started on lorlatinib 100 mg/d (n = 122), a Cox regression model with the occurrence of a dose reduction as a time-dependent covariate indicated no association between dose reduction and PFS (hazard ratio = 0.86, 95% CI: 0.54-1.39) or OS (hazard ratio = 0.78, 95% CI: 0.47-1.30). Conclusions: Lorlatinib dose reductions were not associated with inferior clinical outcomes in this multicenter analysis. Prompt identification of lorlatinib TRAEs and implementation of dose reductions may help maximize tolerability without compromising outcomes.

CodeBreak 200: Sotorasib Has Not Broken the KRASG12C Enigma Code.

Thirteen percent of non-small cell lung cancer (NSCLC) patients are estimated to have the KRAS G12C mutation. Sotorasib is a novel KRAS G12C inhibitor that has shown promising results in preclinical and clinical studies, granting its conditional approval by the FDA in May 2021. The phase I clinical trial resulted in a confirmed response of 32% and progression free survival (PFS) of 6.3 months while the phase II trial resulted in a confirmed response of 37.1% and a PFS of 6.8 months. It was also shown to be tolerable with most subjects experiencing grade one or two adverse events, most commonly diarrhea and nausea. The CodeBreaK 200 phase III trial data have recently resulted and showed an improved PFS with the use of sotorasib at 5.6 months compared to that of standard docetaxel of 4.5 months in locally advanced or unresectable metastatic KRAS G12C NSCLC previously treated with at least one platinum-based chemotherapy and checkpoint inhibitor. The lower than expected PFS of sotorasib from the phase III trial opens up opportunities for other G12C inhibitors to join the field. Indeed, adagrasib, another G12C inhibitor just recently gained FDA accelerated approval in NSCLC patients based on the KRYSTAL-1 study where the response rate was 43% with a median duration of response of 8.5 months. With novel agents and combinations, the field of KRAS G12C is quickly evolving. While sotorasib was an exciting start, there is more to do to break the KRAS G12C Enigma code.

Low-Dose Computed Tomography (LDCT) Lung Cancer Screening in Asian Female Never-Smokers Is as Efficacious in Detecting Lung Cancer as in Asian Male Ever-Smokers: A Systematic Review and Meta-Analysis.

INTRODUCTION: Lung cancer in never-smokers is the major cancer cause of death globally. We compared the efficacy of low-dose computed tomography (LDCT) lung cancer screening among never-smokers versus ever-smokers using systematic review and meta-analysis. METHODS: LDCT lung cancer screening studies that simultaneously included both ever-smoker and never-smoker participants published by April 30, 2021, were searched through PubMed and Scopus. Primary outcome measure was relative risk (RR) of lung cancer diagnosed among never-smokers versus ever-smokers. RESULTS: A total of 14 studies (13 from Asia) were included (141,396 ever-smokers, 109,251 never-smokers, 1961 lung cancer cases diagnosed). RR of lung cancer diagnosed between ever-smokers versus never-smokers overall was 1.21 (95% confidence interval [CI]: 0.89-1.65), 1.37 (95% CI: 1.08-1.75) among males, and 0.88 (95% CI: 0.59-1.31) among females. RR was 1.78 (95% CI: 1.41-2.24) and 1.22 (95% CI: 0.89-1.68) for Asian female never-smokers versus male never-smokers and versus male ever-smokers, respectively, and 0.99 (95% CI: 0.65-1.50) versus high-risk ever-smokers (≥30 pack-years). Proportional meta-analysis revealed significantly more lung cancers diagnosed at first scan (95.4% [95% CI: 84.9-100.0] versus 70.9% [95% CI: 54.6-84.9], p = 0.010) and at stage 1 (88.5% [95% CI: 79.3-95.4] versus 79.7% [95% CI: 71.1-87.4], p = 0.071) among never-smokers versus ever-smokers, respectively. RR of lung cancer death and 5-year all-cause mortality in never-smokers versus ever-smokers was 0.27 (95% CI: 0.1-0.55, p < 0.001) and 0.13 (95% CI: 0.05-0.33, p < 0.001), respectively. CONCLUSIONS: The RR of lung cancer detected by LDCT screening among female never-smokers and male ever-smokers in Asia was statistically similar. Overall and lung cancer specific mortality from the lung cancer diagnosed from LDCT screening was significantly reduced among never-smokers compared to ever-smokers.

Spotlight on Furmonertinib (Alflutinib, AST2818). The Swiss Army Knife (del19, L858R, T790M, Exon 20 Insertions, "uncommon-G719X, S768I, L861Q") Among the Third-Generation EGFR TKIs?

Osimertinib, a third-generation (3G) epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) is now considered the standard of care for the first-line (1L) treatment of advanced EGFR+ NSCLC due to statistically significant improved progression-free survival (PFS) and overall survival (OS) compared with first-generation (1G) treatment from the FLAURA trial. Recently two other 3G EGFR TKIs (aumolertinib and furmonertinib) have been approved in China for treatment of EGFR T790M+ NSCLC. Randomized Phase 3 trials of these two 3G EGFR TKIs have also demonstrated PFS over gefitinib respectively. Among these two Chinese home-grown, 3G EGFR TKIs, furmonertinib seems to most closely resemble osimertinib in terms of dosing regimen, efficacy and adverse events profile. In this article, we reviewed the clinical activity and adverse events of furmonertinib at 80 mg daily (approved dose), potential usage of 160 mg daily for CNS metastasis in EGFR+ NSCLC, and usage of 160 mg or 240 mg daily in EGFR exon20 insertion positive (EGFRex20ins+) NSCLC patients.

A High Percentage of NSCLC With Germline CHEK2 Mutation Harbors Actionable Driver Alterations: Survey of a Cancer Genomic Database and Review of Literature.

Introduction: Germline CHEK2 mutations are rare and have not been associated with increased risk of NSCLC. Methods: We identified two sequential primary NSCLCs harboring distinct actionable driver alterations (EGFR E746 _S752 delinsV and CD74-ROS1) in a patient with NSCLC with a novel germline CHEK2 mutation S5fs∗54 (c.14_20delCGGATGT). We queried a genomic database of NSCLC samples profiled by plasma next-generation sequencing (Foundation Medicine Inc.) and performed a literature search of germline CHEK2 mutations in NSCLC. Results: Of 6101 patients with unique NSCLC profiled by plasma next-generation sequencing, 53 cases (0.87%) of germline CHEK2 mutation were identified (male-to-female ratio, 49%:51%; median age = 75 y). The median allele frequency of CHEK2 was 49% (interquartile range: 49%-51%). Ten unique CHEK2 germline mutations were identified. Literature review identified 15 additional cases of germline CHEK2 mutations in NSCLC. Overall, a total of 70 CHEK2 germline mutations (21 unique CHEK2 alterations) were identified. Among these 70 CHEK2 germline mutations, 54.3% were amino acid substitutions (point mutation), 40.0% were frameshift mutations, and 5.7% were splice site mutations. Of these 70 total cases assessed, 29 (41.4%) potentially actionable driver alterations were identified with KRAS G12C mutation (27.6%) being the most common and KRAS G12A/C/D/R/S/V mutations together constituting 51.7% of these driver mutations. Conclusions: Germline CHEK2 mutations are rare in NSCLC. A large proportion of these cases harbor actionable driver alterations. The relationship between germline CHEK2 mutations and actionable driver alterations in NSCLC may be worth further investigation.

Deconstructing ADAURA: It is Time to Forgo Adjuvant Platinum-Based Chemotherapy in Resected IB-IIIA EGFR+ NSCLC (Except with RB Alterations?) When Adopting Adjuvant Osimertinib.

Adjuvant cisplatin-based chemotherapy is considered the standard of care for resected stage IB (tumor ≥ 4m)-IIIA non-small cell lung cancer (NSCLC). The ADAURA trial is a randomized placebo-controlled Phase III trial that demonstrated statistically significant improved disease-free survival (DFS) with the use of 3-years of adjuvant osimertinib in resected stage IB-IIIA NSCLC harboring epidermal growth factor receptor (EGFR) del 19 or L858R mutations. Subgroup analysis revealed that the DFS improvement with adjuvant osimertinib is independent of adjuvant chemotherapy in the primary analysis. A recent follow-up report suggested that adjuvant cisplatin-based chemotherapy provided no additional 2-year DFS improvement on top of adjuvant osimertinib regardless of stage (IB, II, or IIIA) and minimal numerical DFS benefit in stage II or IIIA resected EGFR+ NSCLC for those patients who did not receive adjuvant osimertinib. Here, we argue that if clinicians adopt the use of 3 years of adjuvant osimertinib in resected early-stage EGFR+ NSCLC, there is no role for adjuvant platinum-based chemotherapy. The use of adjuvant chemotherapy was balanced between the osimertinib and the placebo arms by stage even though adjuvant chemotherapy was not one of the three stratification factors (del 19 vs L858R; Stage IA vs II vs III; Asians versus non-Asian) in ADAURA. There may be a potential role of adjuvant cisplatin/vinorelbine in a small subgroup of EGFR+ NSCLC patients whose tumor harbors retinoblastoma (RB) gene alterations but requires further investigation.

Spotlight on Tepotinib and Capmatinib for Non-Small Cell Lung Cancer with MET Exon 14 Skipping Mutation.

Mesenchymal-epithelial transition (MET) receptor tyrosine kinase is overexpressed, amplified, or mutated in 1-20% of NSCLC. MET dysregulation is associated with a poor prognosis. Recently, development of targeted therapies against MET exon 14 mutations has demonstrated efficacy and tolerability in early trials. Here we focus on tepotinib and capmatinib in regards to molecular characteristics, early preclinical and clinical data, and the emerging role in future studies and clinical practice.

Amivantamab (JNJ-61186372) induces clinical, biochemical, molecular, and radiographic response in a treatment-refractory NSCLC patient harboring amplified triple EGFR mutations (L858R/ T790M/G796S) in cis.

The sequential use of 1st-/2nd-generation to 3rd-generation epidermal growth factor (EGFR) tyrosine kinase inhibitors (TKIs) has led to the emergence of triple EGFR mutations generally consisting of the founder mutation (del 19 or L858R), gatekeeper mutation (T790M) and mutation (C797S) that abolishes the covalent binding of osimertinib to the EGFR protein (i.e., del 19 or L858R/T790M/C797S). Besides C797S, other tertiary mutations confer structural steric hindrance to osimertinib rather than preventing its covalent binding to the EGFR kinase domain such as solvent front mutation (G796S) or others such as L792F/H mutation. "Fourth-generation" EGFR TKIs are being developed to inhibit these triple mutations, in particular, in the background of compound T790M/C797S mutations but they are still in early clinical stages of development. Amivantamab, a bi-specific EGFR/MET monoclonal antibody that can affect Fc mediated trogocytosis of the EGFR protein has been approved for the treatment of EGFR exon20 insertion mutations and has demonstrated activity against a myriad of compound EGFR mutations. Here we report amivantamab monotherapy induced symptomatic, biochemical, molecular, and radiographic responses in a NSCLC patient with triple EGFR mutations in cis in the background of EGFR amplification.

Spotlight on Sotorasib (AMG 510) for KRAS G12C Positive Non-Small Cell Lung Cancer.

Mutations in codon 12 of KRAS have been identified in 13% of non-small cell lung cancer patients. Developing targeted therapies against KRASG12C mutation has proven to be challenging due to the abundance of GTP in the cytoplasm, rapid hydrolysis of GTP, and difficulty designing small molecules to achieve sufficient concentration for KRAS inhibition. Based on promising results in both preclinical and clinical trials, sotorasib, a novel KRASG12C inhibitor, was given conditional approval by the FDA in May 2021. The Phase I portion of the clinical trial produced 32% confirmed response with 56% of patients with stable disease. About 91.2% of patients who received the highest dose of 960mg daily achieved disease control. The Phase II portion, which used 960mg daily dosing resulted in 37.1% of patients with confirmed response and 80.6% of patients with disease control. Both phase I and phase II had similar progression-free survival, in 6.3 months and 6.8 months, respectively. In both phases, grade 4 adverse events occurred in only one patient. The most common adverse events were elevations in LFTs, which down-trended upon dose reduction and steroid treatment. While the conditional approval of sotorasib was a major breakthrough for those patients harboring KRASG12C mutations, resistance mutations to sotorasib are increasingly common. Many proposals have been made to address this, such as the use of combination therapy for synthetic lethality, which are producing encouraging results. Here, we explore in further detail the development of sotorasib, its efficacy, mechanism of resistance, and strategies to overcome these resistances.

Identification of Novel CDH1-NRG2α and F11R-NRG2α Fusions in NSCLC Plus Additional Novel NRG2α Fusions in Other Solid Tumors by Whole Transcriptome Sequencing.

INTRODUCTION: A novel CD74-NRG2α fusion has recently been identified in NSCLC. We surveyed a large tumor database comprehensively profiled by whole transcriptome sequencing to investigate the incidence and distribution of NRG2 fusions among various solid tumors. METHODS: Tumor samples submitted for clinical molecular profiling at Caris Life Sciences (Phoenix, AZ) that underwent whole transcriptome sequencing (NovaSeq [Illumina, San Diego, CA]) were retrospectively analyzed for NRG2 fusion events. All NRG2 fusions with sufficient reads (> three junctional reads spanning ≥ seven nucleotides) were identified for manual review, characterization of fusion class, intact functional domains, EGF-like domain isoforms, breakpoints, frame retention, and co-occurring alterations by next-generation sequencing (NextSeq [Illumina, San Diego, CA], 592 genes). RESULTS: Seven inframe functional (containing the intact EGF-like domain) NRG2α fusions were identified, namely, the following: (1) NSCLC (two of 9600, 0.02%: CDH1-NRG2α [C11, N2], F11R-NRG2α [F1, N4]); (2) endometrial (two of 3060, 0.065%: CPM-NRG2α [C2, N2], OPA3-NRG2α [O1, N2]); (3) ovarian (one of 5030, 0.02%: SPON1-NRG2α [S6, N2]); (4) prostate (one of 1600, 0.063%: PLPP1-NRG2α [P1, N2]); and (5) carcinoma of unknown origin (one of 1400, 0.07%: CYSTM1-NRG2α [C2, N2]). No NRG2ß fusions were identified. Both NSCLC samples contained the reciprocal NRG2 fusions (NRG2-CDH1, NRG2-F11R). Almost all inframe NRG2α fusions have no (N = 6, 85.7%) or low (N = 1, 14.3%) programmed death-ligand 1 expression. No additional known driver mutations were identified in these seven NRG2α fusion-positive tumor samples. CONCLUSIONS: Similar to NRG1 fusions, NRG2α fusions are recurrent and rare ligand-fusions in NSCLC and other multiple tumor types, especially gynecologic malignancies.

Spotlight on Mobocertinib (TAK-788) in NSCLC with EGFR Exon 20 Insertion Mutations.

The EGFR exon 20 insertion (EGFRex20ins) mutations are the third most common EGFR mutations seen in non-small cell lung cancer (NSCLC). More than 50 variants of EGFRex20ins mutations have been identified with A767_V769dupASV being the most common variant across multiple surveys. Treatment with currently available EGFR tyrosine kinase inhibitors (TKIs) including osimertinib is generally ineffective. Amivantamab (JNJ-372), a bispecific monoclonal antibody against EGFR and MET, has recently been approved by the US FDA for patients with advanced or metastatic NSCLC harboring EGFRex20ins mutations after disease progression on platinum-based chemotherapy. Among all the TKIs in clinical development, mobocertinib (TAK-788) has been granted priority review by the FDA for the same indication as amivantamab. Here, we provide a concise review on mobocertinib, with a focus on its chemical structure, preclinical data, and phase 1/2 trial results. Future directions will likely focus on combination approach such as TKI plus chemotherapy in the first-line setting, designing drugs with CNS activity, and exploring disease characteristics of various EGFRex20ins mutation variants and how they may affect treatment response.

Going beneath the tip of the iceberg. Identifying and understanding EML4-ALK variants and TP53 mutations to optimize treatment of ALK fusion positive (ALK+) NSCLC.

Since the discovery of echinoderm microtubule-associated protein-like 4 (EML4) and anaplastic lymphoma kinase (ALK) gene fusion in non-small cell lung carcinoma (NSCLC) in 2007, more than 10 EML4-ALK variants based on the exon breakpoints in EML4 have been identified. Unlike other receptor tyrosine kinase fusion positive NSCLC such as ROS1 or RET fusion, EML4-ALK is the dominant fusion variant in ALK+ NSCLC accounting for approximately 85 % of all fusion variants in ALK+ NSCLC. Currently, eight EML4-ALK variants are generally recognized with a number (1, 2, 3a/b, 4', 5a/b, 5', 7, 8) with EML4-ALK variants 1 and 3 being the two most common variants accounting for 75-80 % of the total EML4-ALK variants. Preclinical, retrospective analyses of institutional databases, and global randomized phase 3 trials have demonstrated differential clinical response (overall response rate, progression-free survival) to ALK tyrosine kinase inhibitors (TKIs) between the "short" (v3 and v5) and "long" (v1, v2, v5', v7, and v8) EML4-ALK variants. We discuss in more details how EML4-ALK variant structure influences protein stability and response to ALK TKIs. Additionally, the most recalcitrant single solvent-front mutation ALK G1202R is more prone to develop among EML4-ALK v3 following sequential use of next-generation ALK TKIs. Furthermore, TP53 mutations being the most common genomic co-alterations in ALK+ NSCLC also contribute to the heterogeneous response to ALK TKIs. Recognizing ALK+ NSCLC is not one homogeneous disease entity but comprised of different ALK fusion variants with different underlying genomic alterations in particular TP53 mutations that modulate treatment response will provide insight into the further optimization of treatment of ALK+ NSCLC patients potentially leading to improvement in survival.

Acquired Resistance to KRASG12C Inhibition in Cancer.

BACKGROUND: Clinical trials of the KRAS inhibitors adagrasib and sotorasib have shown promising activity in cancers harboring KRAS glycine-to-cysteine amino acid substitutions at codon 12 (KRASG12C). The mechanisms of acquired resistance to these therapies are currently unknown. METHODS: Among patients with KRASG12C -mutant cancers treated with adagrasib monotherapy, we performed genomic and histologic analyses that compared pretreatment samples with those obtained after the development of resistance. Cell-based experiments were conducted to study mutations that confer resistance to KRASG12C inhibitors. RESULTS: A total of 38 patients were included in this study: 27 with non-small-cell lung cancer, 10 with colorectal cancer, and 1 with appendiceal cancer. Putative mechanisms of resistance to adagrasib were detected in 17 patients (45% of the cohort), of whom 7 (18% of the cohort) had multiple coincident mechanisms. Acquired KRAS alterations included G12D/R/V/W, G13D, Q61H, R68S, H95D/Q/R, Y96C, and high-level amplification of the KRASG12C allele. Acquired bypass mechanisms of resistance included MET amplification; activating mutations in NRAS, BRAF, MAP2K1, and RET; oncogenic fusions involving ALK, RET, BRAF, RAF1, and FGFR3; and loss-of-function mutations in NF1 and PTEN. In two of nine patients with lung adenocarcinoma for whom paired tissue-biopsy samples were available, histologic transformation to squamous-cell carcinoma was observed without identification of any other resistance mechanisms. Using an in vitro deep mutational scanning screen, we systematically defined the landscape of KRAS mutations that confer resistance to KRASG12C inhibitors. CONCLUSIONS: Diverse genomic and histologic mechanisms impart resistance to covalent KRASG12C inhibitors, and new therapeutic strategies are required to delay and overcome this drug resistance in patients with cancer. (Funded by Mirati Therapeutics and others; ClinicalTrials.gov number, NCT03785249.).