Refining patient selection of MET-activated non-small cell lung cancer through biomarker precision.

Dysregulated MET signaling plays an important role in lung oncogenesis, tumor growth and invasiveness. It may occur through various mechanisms, such as MET overexpression or gene amplification or mutation, all of which can be detected by specific methods. The utility of MET overexpression as a biomarker remains unclear due to discrepancies in its occurrence and non-standardized cut-off thresholds. MET exon 14 skipping mutation (METex14) was established as a strong predictor of response to selective MET tyrosine kinase inhibitors (TKIs), and clinical trial results in patients with non-small cell lung cancer (NSCLC) harboring METex14 led to the approval of capmatinib and tepotinib by regulatory agencies worldwide. MET amplification is an emerging biomarker, with clinical data indicating an association between MET gene copy number and response to MET-TKIs. Additionally, MET amplification represents an important mechanism of resistance to TKIs in oncogene-driven NSCLC. The identification of molecular alterations for which targeted therapies are available is important, and high-throughput next-generation sequencing techniques can provide information on multiple genes at the same time, helping to provide valuable predictive information for oncogene-driven cancers. This review summarizes the current methods used for the detection of METex14, MET amplification and MET overexpression, and discusses the evidence for the use of MET-TKIs in patients with NSCLC with MET dysregulation. We discuss the practical challenges that impact the use of METex14 in the clinic and the evidence gaps that need to be addressed to validate additional genomic markers for MET-dependent cancers.

Phase 1 multicenter study of the HSP90 inhibitor SNX-5422 plus carboplatin and paclitaxel in patients with lung cancers.

OBJECTIVES: Single-agent heat shock protein 90 (HSP90) inhibition has demonstrated activity in oncogene-driven non-small cell and small cell lung cancers. SNX-5422 is an oral HSP90 inhibitor with increased activity in vitro with the addition of carboplatin and paclitaxel. Therefore, we conducted a phase 1, open-label, multicenter study to evaluate SNX-5422, carboplatin and paclitaxel followed by SNX-5422 maintenance in patients with advanced lung cancers. MATERIALS AND METHODS: In part 1 (3 + 3 dose escalation), SNX-5422 (50/75/100-mg/m2) was dosed every other day (qod) for 21 days (28-day cycle) for ≤4 cycles; carboplatin (AUC 5)-paclitaxel (175 mg/m2) was administered once every 3 weeks for ≤6 courses. In part 2 (maintenance), subjects who achieved at least stable disease in part 1 received 100 mg/m2 SNX-5422 monotherapy qod for 21 days (28-day cycle). RESULTS: Twenty-three patients with advanced non-small cell lung cancer (NSCLC, n = 20) and small cell lung cancer (SCLC, n = 3) were enrolled. The median age was 60 years and 61% (n = 14/23) had ≥1 prior treatment regimens. The maximum tolerated dose of SNX-5422 was 100 mg/m2 qod in combination with carboplatin-paclitaxel. The most common treatment-related grade 3/4 adverse events (part 1/part 2) were diarrhea (26%/15%) and nausea (9%/0%). In response-evaluable patients with NSCLC, 33% (6/18) had a partial response, 56% (10/18) stable disease, and 11% (2/18) progressive disease. Patients who remained on single-agent SNX-5422 maintenance therapy ≥2 months (n = 9) had cancers enriched for oncogenic drivers (n = 3 KRAS mutation, n = 1 EGFR exon 20 mutation, n = 1 HER2 mutation, and n = 1 RET fusion). CONCLUSIONS: The triplet combination of SNX-5422, carboplatin and paclitaxel followed by maintenance SNX-5422 therapy was well-tolerated and showed anti-tumor activity. Cancers for which disease control on single-agent SNX-5422 maintenance was observed were enriched for oncogene-driven NSCLCs.

MET Exon 14-altered Lung Cancers and MET Inhibitor Resistance.

PURPOSE: MET tyrosine kinase inhibitors (TKIs) can achieve modest clinical outcomes in MET exon 14-altered lung cancers, likely secondary to primary resistance. Mechanisms of primary resistance remain poorly characterized and comprehensive proteomic analyses have not previously been performed. EXPERIMENTAL DESIGN: We performed hybrid capture-based DNA sequencing, targeted RNA sequencing, cell-free DNA sequencing, selected reaction monitoring mass spectrometry (SRM-MS), and immunohistochemistry on patient samples of MET exon 14-altered lung cancers treated with a MET TKI. Associations between overall response rate (ORR), progression-free survival (PFS), and putative genomic alterations and MET protein expression were evaluated. RESULTS: Seventy-five of 168 MET exon 14-altered lung cancers received a MET TKI. Previously undescribed (zygosity, clonality, whole-genome duplication) and known (copy-number focality, tumor mutational burden, mutation region/type) genomic factors were not associated with ORR/PFS (P > 0.05). In contrast, MET expression was associated with MET TKI benefit. Only cases with detectable MET expression by SRM-MS (N = 15) or immunochemistry (N = 22) responded to MET TKI therapy, and cancers with H-score ≥ 200 had a higher PFS than cancers below this cutoff (10.4 vs. 5.5 months, respectively; HR, 3.87; P = 0.02). CONCLUSIONS: In MET exon 14-altered cancers treated with a MET TKI, a comprehensive analysis of previously unknown and known genomic factors did not identify a genomic mechanism of primary resistance. Instead, MET expression correlated with benefit, suggesting the potential role of interrogating the proteome in addition to the genome in confirmatory prospective trials.

CNS Metastases in Patients With MET Exon 14-Altered Lung Cancers and Outcomes With Crizotinib.

PURPOSE: Although MET exon 14 (METex14)-altered lung cancers were first identified more than a decade and a half ago, the frequency of CNS metastatic disease remains poorly defined. Furthermore, the seminal trial of crizotinib in these patients (PROFILE 1001) did not report patterns of CNS response or progression. PATIENTS AND METHODS: Patients with pathologically confirmed, advanced non-small-cell lung cancers (NSCLC) harboring a METex14 alteration by targeted DNA/RNA sequencing were studied. The incidence of brain metastases and the outcomes of MET inhibition with crizotinib were analyzed. RESULTS: Eighty-three patients with METex14-altered metastatic NSCLC were identified. The incidence of CNS metastases at diagnosis was 17% (95% CI, 10% to 27%). The lifetime incidence was 36% (95% CI, 26% to 47%); 83% of patients had parenchymal disease, and 17% had leptomeningeal disease. The probability of having brain metastasis at 1, 2, and 3 years was 24%, 35%, and 38%, respectively. Fifty-four patients received crizotinib. The median time to radiologic CNS progression was 5.8 months (range, 3.7-20.0 months). Patterns of crizotinib progression were as follows: intracranial only in 10% of patients, intracranial and extracranial in 12%, and extracranial only in 78%. In patients with brain metastases before treatment, the median time on crizotinib was 7.5 months (range, 7.2-11.7 months). CONCLUSION: CNS metastases, including leptomeningeal disease, occurred in more than a third of patients with METex14-altered lung cancers. In crizotinib-treated patients with or without CNS metastases, CNS failure was seen in less than a quarter of patients on progression.

MET-dependent solid tumours - molecular diagnosis and targeted therapy.

Attempts to develop MET-targeted therapies have historically focused on MET-expressing cancers, with limited success. Thus, MET expression in the absence of a genomic marker of MET dependence is a poor predictor of benefit from MET-targeted therapy. However, owing to the development of more sensitive methods of detecting genomic alterations, high-level MET amplification and activating MET mutations or fusions are all now known to be drivers of oncogenesis. MET mutations include those affecting the kinase or extracellular domains and those that result in exon 14 skipping. The activity of MET tyrosine kinase inhibitors varies by MET alteration category. The likelihood of benefit from MET-targeted therapies increases with increasing levels of MET amplification, although no consensus exists on the optimal diagnostic cut-off point for MET copy number gains identified using fluorescence in situ hybridization and, in particular, next-generation sequencing. Several agents targeting exon 14 skipping alterations are currently in clinical development, with promising data available from early-phase trials. By contrast, the therapeutic implications of MET fusions remain underexplored. Here we summarize and evaluate the utility of various diagnostic techniques and the roles of different classes of MET-targeted therapies in cancers with MET amplification, mutation and fusion, and MET overexpression.

Novel Germline Mutations in DNA Damage Repair in Patients with Malignant Pleural Mesotheliomas.

INTRODUCTION: Although next-generation sequencing (NGS) has brought insight into critical mutations or pathways (e.g., DNA damage sensing and repair) involved in the etiology of many cancers and has directed new screening, prevention, and therapeutic approaches for patients and families, it has only recently been used in malignant pleural mesotheliomas (MPMs). METHODS: We analyzed the blood samples from patients with MPM using the NGS platform MSK-IMPACT to explore cancer-predisposing genes. The loss-of-function variants or pathogenic entries were identified, and clinicopathologic information was collected. RESULTS: Of 84 patients with MPM, 12% (10 of 84) had pathogenic variants. Clinical characteristics were similar between cohorts, although patients with germline pathogenic variants were more likely to have more than two first-degree family members with cancer than those without germline mutations (40% versus 12%; Fisher's exact test, p < 0.05). Novel, deleterious variants in mesotheliomas included MutS homolog 3 (1% [one of 84]; 95% confidence interval [CI]: 0%-7%), breast cancer gene 1-associated ring domain 1 (1% [one of 84]; 95% CI: 0%-7%), and RecQ-like helicase 4 (2% [two of 84]; 95% CI: 0%-9%). Pathogenic variants previously reported on germline testing in patients with mesotheliomas were breast cancer gene 1-associated protein 1 (4% [three of 84]; 95% CI: 1%-10%), breast cancer gene 2 (1% [one of 84]; 95% CI: 0%-7%), and MRE11 homolog, double strand break repair nuclease (1% [one of 84]; 95% CI: 0%-7%). One patient (1% [one of 84]; 95% CI: 0%-7%) had a likely pathogenic alteration in SHQ1, H/ACA ribonucleoprotein assembly factor that has not been associated with a heritable susceptibility to cancer. CONCLUSIONS: Our study lends further support for the role of aberrations in DNA damage repair genes in the pathogenesis of MPMs and suggests that targeting the members of these pathways for screening and treatment warrants further study.

MET IHC Is a Poor Screen for MET Amplification or MET Exon 14 Mutations in Lung Adenocarcinomas: Data from a Tri-Institutional Cohort of the Lung Cancer Mutation Consortium.

INTRODUCTION: MNNG HOS Transforming gene (MET) amplification and MET exon 14 (METex14) alterations in lung cancers affect sensitivity to MET proto-oncogene, receptor tyrosine kinase (MET [also known by the alias hepatocyte growth factor receptor]) inhibitors. Fluorescence in situ hybridization (FISH), next-generation sequencing (NGS), and immunohistochemistry (IHC) have been used to evaluate MET dependency. Here, we have determined the association of MET IHC with METex14 mutations and MET amplification. METHODS: We collected data on a tri-institutional cohort from the Lung Cancer Mutation Consortium. All patients had metastatic lung adenocarcinomas and no prior targeted therapies. MET IHC positivity was defined by an H-score of 200 or higher using SP44 antibody. MET amplification was defined by copy number fold change of 1.8x or more with use of NGS or a MET-to-centromere of chromosome 7 ratio greater than 2.2 with use of FISH. RESULTS: We tested tissue from 181 patients for MET IHC, MET amplification, and METex14 mutations. Overall, 71 of 181 patients (39%) were MET IHC-positive, three of 181 (2%) were MET-amplified, and two of 181 (1%) harbored METex14 mutations. Of the MET-amplified cases, two were FISH positive with MET-to-centromere of chromosome 7 ratios of 3.1 and 3.3, one case was NGS positive with a fold change of 4.4x, and one of the three cases was MET IHC-positive. Of the 71 IHC-positive cases, one (1%) was MET-amplified and two (3%) were METex14-mutated. Of the MET IHC-negative cases, two of 110 (2%) were MET-amplified. CONCLUSIONS: In this study, nearly all MET IHC-positive cases were negative for MET amplification or METex14 mutations. MET IHC can also miss patients with MET amplification. The limited number of MET-amplified cases in this cohort makes it challenging to demonstrate an association between MET IHC and MET amplification. Nevertheless, IHC appears to be an inefficient screen for these genomic changes. MET amplification or METex14 mutations can best be detected by FISH and a multiplex NGS panel.

Potentially inappropriate medication use in elderly non-Hodgkin lymphoma patients is associated with reduced survival and increased toxicities.

Survival outcomes for elderly lymphoma patients are disproportionally inferior to those of younger patients. We examined medication usage at diagnosis for 171 elderly patients (median age 70 years) with aggressive non-Hodgkin lymphoma treated between 2009 and 2014. At least one potentially inappropriate medication was used in 47% of patients according to the Beers Criteria, 59% experienced treatment delays and/or dose reduction and 65% experienced ≥ grade 3 treatment-related toxicities. We report here for the first time that potentially inappropriate medication use was associated with reduced progression-free survival and overall survival, and increased ≥ grade 3 treatment-related toxicities in multivariate analysis.

Chromosomal instability triggered by Rrm2b loss leads to IL-6 secretion and plasmacytic neoplasms.

Chronic inflammation has a tight cause-and-effect relationship with DNA damage by inflicting tissue damage and increasing cancer risk. Rrm2b, a key enzyme in de novo deoxyribonucleotide synthesis, is involved in DNA damage repair, but its role in cancer development has yet to be demonstrated. In this work, Rrm2b gene loss led to severe numerical and structural chromosome abnormalities that caused ATM activation, inducing p-Ser85 IKKγ/NEMO and IκB kinase (IKK). NF-κB consequently induced by IKK triggered sustained IL-6 expression that constitutively activated STAT3 in Rrm2b-deficient cells. High plasma interleukin-6 (IL-6) and associated hematologic disorders were observed in Rrm2b-/- mice, and 30%-40% of aged Rrm2b heterozygous knockout mice developed plasma cell neoplasms and suffered from progressive splenomegaly and ascites. The genetic ablation of IL-6 suppressed STAT3 induction and delayed disease onset in Rrm2b-/- mice, extending their lifespan. Thus, Rrm2b plays a crucial role in maintaining chromosomal stability and preventing chronic-inflammation-associated tumorigenesis.

ATM-mediated serine 72 phosphorylation stabilizes ribonucleotide reductase small subunit p53R2 protein against MDM2 to DNA damage.

Ribonucleotide reductase small subunit p53R2 was identified as a p53 target gene that provides dNTP for DNA damage repair. However, the slow transcriptional induction of p53R2 in RNA may not be rapid enough for prompt DNA damage repair, which has to occur within a few hours of damage. Here, we demonstrate that p53R2 becomes rapidly phosphorylated at Ser(72) by ataxia telangiectasia mutated (ATM) within 30 min after genotoxic stress. p53R2, as well as its heterodimeric partner RRM1, are associated with ATM in vivo. Mutational studies further indicate that ATM-mediated Ser(72) phosphorylation is essential for maintaining p53R2 protein stability and conferring resistance to DNA damage. The mutation of Ser(72) on p53R2 to alanine results in the hyperubiquitination of p53R2 and reduces p53R2 stability. MDM2, a ubiquitin ligase for p53, interacts and facilitates ubiquitination of the S72A-p53R2 mutant more efficiently than WT-p53R2 after DNA damage in vivo. Our results strongly suggest a novel mechanism for the regulation of p53R2 activity via ATM-mediated phosphorylation at Ser(72) and MDM2-dependent turnover of p53R2 dephosphorylated at the same residue.