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Supplementary Figures S1-S6, Table S1-S3, and eMethods

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.

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.

The Bromodomain and Extra-Terminal (BET) Domain proteins facilitate the development of many human cancers via epigenetic regulation. BET inhibitors may be effective in reversing platinum resistance in ovarian cancer (OC) and may generate synthetic lethality with ARID1A loss. PLX2853 is an orally active, small molecule inhibitor of BET bromodomain-mediated interactions that exhibits low nanomolar potency in blocking all 4 BET family members (BRD2, BRD3, BRD4, and BRDT). PLX2853 development is continuing at Opna Bio as OPN-2853. Clinical experience with PLX2853 monotherapy in subjects with heavily pretreated solid tumors and lymphoma showed signs of activity. The current study (NCT04493619) was designed as a multicenter, open-label trial with two parallel arms: (1) a phase 2a study of PLX2853 monotherapy in advanced gynecological malignancies with a known ARID1A mutation and (2) a phase Ib/2a combination study of PLX2853 plus carboplatin in platinum resistant OC. The primary objective of the Ib portion of the study was safety and tolerability, with the primary objective of both phase 2a portions being efficacy. In the monotherapy arm, up to 6 patients were treated at 80 mg PLX2853 daily in a safety lead-in, with progression to phase 2a using a Simon 2-stage design if dose limiting toxicities (DLTs) were observed in fewer than 33% subjects. In Stage 1, 6 additional subjects (N=12 total) were planned, with progression to stage 2 if two or more patients responded in stage 1. The combination arm included an escalation phase Ib. Three to six evaluable subjects were planned for each group, with dose escalation pending less than 33% DLT rate. The combination arm defined by the phase 1b portion of the study continued to a planned phase 2a Simon 2 stage design similar to that described for the monotherapy arm. 34 of 37 enrolled patients were evaluable with data from at least 1 post-baseline response (14 monotherapy, 20 combination therapy). Of the 14 evaluable patients on the monotherapy arm, 1 (7.1%) achieved a partial response (PR) with progression-free survival of 278 days, 5 (35.7%) had stable disease (SD) and 8 (57.1%) had progressive disease (PD). Of the 20 evaluable OC patients on the PLX2843 + carboplatin combination, 1 (5.0%) had PR, 9 (45.0%) had SD, and 10 (50%) had PD. This study in a larger cohort of gynecologic cancer patients confirmed the safety profile of the agent and demonstrated the feasibility of combination with carboplatin. While these results did not meet the pre-specified response criteria, evidence of clinical activity nevertheless highlights the rationale for further exploration of BRD4 inhibitors in patients with ARID1A-mutated gynecologic malignancies, possibly in combination with agents targeting potential feedback mechanisms such as the PI3K pathway, frequently activated in these cancers. Citation Format: Elizabeth M. Swisher, Linda R. Duska, Erika P. Hamilton, Amit M. Oza, Gini Fleming, Oladapo O. Yeku, Alexander I. Spira, Debra L. Richardson, Robin Guo, Jackie Walling, Kerry Inokuchi, Dmitriy Zamarin. Phase 1b/2a clinical trial of the oral BET inhibitor PLX2853 as monotherapy for ARID1A mutated gynecologic cancers and in combination with carboplatin for platinum resistant ovarian cance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT160.

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.

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.

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.

The development of leptomeningeal metastases is a poor prognostic factor in patients with advanced cancers.1–3 In non–small-cell lung cancers (NSCLCs), median overall survival of patients from the diagnosis of leptomeningeal disease is 1 to 2 months without treatment and up to 8 months with systemic therapy.4–6 Furthermore, patients with leptomeningeal disease have historically had limited access to novel therapies in clinical trials. Recent efforts from many groups, including the European Society for Medical Oncology and the US Food and Drug Administration (FDA), have encouraged the inclusion of patients with leptomeningeal metastases in clinical trials, in addition to promoting standardization of intracranial response assessments.7–9 These efforts are crucial given that many investigational agents have substantial CNS activity and may improve outcomes in driver-positive cancers with leptomeningeal involvement.5,10 RET fusions are actionable oncogenic drivers that are identified in 1% to 2% of NSCLCs.11,12 To date,chemotherapy and/or immunotherapy remain the only approved systemic therapies for these cancers. Multikinase inhibitors with activity against RET (eg, cabozantinib or vandetanib) were repurposed to treat patients with RET fusion-positive lung cancers. Although these agents were found to be active in a subset of these patients, outcomes are modest compared with targeted therapies in other driver-positive lung cancers, and intracranial activity is poor.13,14 Selective RET inhibitors currently in development, such as LOXO-292 and BLU-667, have improved outcomes for patients with RET fusion-positive cancers because of increased potency and less offtarget toxicity.15,16 In September of 2018, LOXO-292 received Breakthrough Therapy designation from the FDA for treatment of patients with metastatic RET fusion-positive NSCLCs (as well as RET fusion-positive thyroid cancers and RET-mutant medullary thyroid cancer). In addition, confirmed intracranial responses and durable disease control have been achieved in patients with brain metastases in an ongoing phase I/II trial of LOXO-292 for patients with RET fusion-positive cancers.15 Its activity in leptomeningeal disease, however, has not previously been characterized. In this article, we describe a patient with a RET fusion-positive lung cancer with brain and leptomeningeal metastases who had an impactful intracranial response to selective RET inhibition with LOXO-292.

5583 Background: EC and a subset of OVCA are associated with high rates of dMMR and are responsive to PD-1 blockade. It is unknown what additional biomarkers beyond dMMR may enrich for benefit in these patients (pts). Methods: This was an investigator-initiated, single-arm, phase II study. Eligible pts had recurrent EC or OVCA that met one of the following criteria: 1) dMMR, as determined by immunohistochemical loss of expression of 1+ MMR genes; 2) MSI-H, as determined by next generation sequencing (MSK-IMPACT); or 3) hypermutated, defined as 20+ non-synonymous somatic mutations. Pts received nivo 240mg IV every 2 weeks or 480mg IV every 4 weeks until toxicity or progression. The co-primary endpoints were 1) the progression-free survival (PFS) rate at 24 weeks (PFS24) and 2) the objective response rate (ORR) by RECIST v1.1. The study was designed using Simon’s two-stage design, with a sample size of 40 pts based on a promising ORR of 25% with a type I error rate of 0.025 and a type II error rate of 0.05. Overall survival (OS), PFS and duration of response (DOR) were calculated using the method of Kaplan-Meier. Adverse events (AEs) were graded per CTCAE and tabulated. Biomarker analyses on the available archival tissue were performed using multiplex immunofluorescence (mIF) labeling for CD8, PD-1, TOX, PD-1, PD-L1, and FoxP3. Quantification of immune phenotypes and interaction studies between CD8+ T cells and PD-L1+ cells was performed in HALO. Results: Between 9/2017 and 5/2021, 35 pts were enrolled; the study closed early due to slow accrual. The median duration of follow-up was 33.2 months. The median age was 64 years (range 36-87); 82% of pts were white, 54% had high grade EC, and 65% had confirmed MLH1 hypermethylation. The ORR was 57.1% (97.5% CI 39.4-100%) [37% PR, 20% CR]. The PFS24 was 62.9% and median PFS was 26.7 months (95% CI 4.9-NE). Neither median DOR nor OS was reached. OS at 1 year was 76.4% (95% CI 58.2-87.4%). The ORR in patients with MLH1 hypermethylation was 52%; 4 of 5 patients with confirmed germline MMR alterations had a response by RECIST. AEs were consistent with the reported literature. Notable treatment related AEs included Grade 4 myocarditis with associated grade 4 AV block, grade 2 extraocular paresis, grade 3 Type 1 diabetes mellitus, and grade 3 elevations in AST/ALT. On mIF analysis, PD-L1 expression did not distinguish responders from non-responders, though interaction between CD8+ T cells and PD-L1+ cells was associated with CR/PR. Increase in relative fraction of dysfunctional CD8+ T cells (characterized by CD8+TOX+PD-1+ phenotype) was also associated with CR/PR. Conclusions: Nivo is an effective and tolerable treatment option for patients with MMR-D/MSI-H or hypermutated EC or OVCA. Presence of dysfunctional CD8+ T cells in the tumors was associated with response, while expression of PD-L1 was not predictive. Clinical trial information: NCT03241745.

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.

Background The tropomyosin receptor kinase (TRK) pathway controls appetite, balance, and pain sensitivity. While these functions are reflected in the on-target adverse events (AEs) observed with TRK inhibition, these AEs remain under-recognized, and pain upon drug withdrawal has not previously been reported. As TRK inhibitors are approved by multiple regulatory agencies for TRK or ROS1 fusion-positive cancers, characterizing these AEs and corresponding management strategies is crucial. Patients and methods Patients with advanced or unresectable solid tumors treated with a TRK inhibitor were retrospectively identified in a search of clinical databases. Among these patients, the frequency, severity, duration, and management outcomes of AEs including weight gain, dizziness or ataxia, and withdrawal pain were characterized. Results Ninety-six patients with 15 unique cancer histologies treated with a TRK inhibitor were identified. Weight gain was observed in 53% [95% confidence interval (CI), 43%–62%] of patients and increased with time on TRK inhibition. Pharmacologic intervention, most commonly with glucagon-like peptide 1 analogs or metformin, appeared to result in stabilization or loss of weight. Dizziness, with or without ataxia, was observed in 41% (95% CI, 31%–51%) of patients with a median time to onset of 2 weeks (range, 3 days to 16 months). TRK inhibitor dose reduction was the most effective intervention for dizziness. Pain upon temporary or permanent TRK inhibitor discontinuation was observed in 35% (95% CI, 24%–46%) of patients; this was more common with longer TRK inhibitor use. TRK inhibitor reinitiation was the most effective intervention for withdrawal pain. Conclusions TRK inhibition-related AEs including weight gain, dizziness, and withdrawal pain occur in a substantial proportion of patients receiving TRK inhibitors. This safety profile is unique relative to other anticancer therapies and warrants careful monitoring. These on-target toxicities are manageable with pharmacologic intervention and dose modification.

Survival outcomes for elderly lymphoma patients are disproportionally inferior to those of younger patients. We examined medication usage at diagnosis for 171 elderly patients with aggressive non-Hodgkin’s lymphoma (median age 70 years) treated from 2009-2014. We found that 47% of patients used at least one potentially inappropriate medication according to the Beers Criteria, and 59% experienced treatment delays and/or dose reduction, and 65% experienced ≥ grade 3 treatment-related toxicities. We reported 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.

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).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.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, p0.05). 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.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.

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.

RET rearrangements are identified in 1% to 2% of non-small-cell lung cancers (NSCLCs).1,2 In patients with advanced, RET-rearranged lung cancers, systemic therapy can be highly active. We demonstrated previously that pemetrexed-based chemotherapy can achieve an objective response rate of 45% and a median progression-free survival (PFS) of 19 months.3 Furthermore, the activity of targeted therapy has improved dramatically with the introduction of selective RET inhibitors to the clinic. In early-phase testing, objective response rates with LOXO-2924 and BLU-6675 are 68% (26 of 38) and 50% (seven of 14), respectively. These outcomes exceed the modest activity observed previously with multikinase inhibitors such as cabozantinib6 and vandetanib.7 In contrast, the activity of immunotherapy in RET-rearranged lung cancers has not been well characterized. This represents a clear unmet need, given that all prior regulatory approvals of immune checkpoint inhibitors, either alone or in combination with chemotherapy, and in stage III or IV disease, have technically included patients with RET-rearranged lung cancers.8,9 Furthermore, although increasing levels of programmed death-ligand 1 (PD-L1) expression and high tumor mutational burden (TMB) have been associated with benefit from immune checkpoint blockade,10 the immunophenotype of RET-rearranged lung cancers and the role of PD-L1 and TMB status in relation to benefit with immunotherapy remain poorly described. We set out to characterize these factors.

9006 Background: MET exon 14 alterations comprise a novel class of lung cancer drivers. MET tyrosine kinase inhibitors (TKIs) are active in patients with these cancers, but objective response rates (ORRs) are modest (~30%-40%). A subset of these cancers may harbor intrinsic resistance. Moreover, patients with initial benefit invariably develop acquired resistance. We set out to identify potential resistance mechanisms. Methods: We studied patients with stage IV MET exon 14-altered lung cancers who received a MET TKI. When feasible, tumor and/or plasma samples were collected, prioritizing paired pre- and post-TKI collection. Tumor samples underwent targeted mass spectrometry analysis (Nantomics) and DNA- (including MSK-IMPACT)/RNA-based (MSK-Fusion) next-generation sequencing (NGS). Plasma cfDNA underwent targeted NGS. ORR and progression-free survival (PFS) were assessed (RECIST v1.1). Results: 74 patients received a MET TKI (1 TKI n = 55; ≥2 TKIs n = 19). 91% received crizotinib as their 1st TKI. Pre-TKI MET levels in tumor tissue (range 0-2120 amol/µg) were associated with outcomes: ORR 63% (n = 7/11) and median PFS 6.9 mos with detectable MET vs ORR 0% (n = 0/5) and median PFS 4.6 mos with undetectable MET (HR for PFS 0.3). Pre-TKI RAS pathway activation was associated with response: ORR 0% (n = 0/6) with KRAS/NF1/RASA1 mutation vs ORR 29% (n = 25/87) in others. Similar outcomes were observed with pre-TKI KRAS expression (n = 16, all with detectable KRAS levels): ORR 0% (n = 0/2) in KRAS ≥700 amol/µg vs ORR 50% (n = 7/14) < 700 amol/µg. Acquired resistance (Jackman criteria) was seen in 29 patients, 9 with paired pre-/post-treatment samples. On-target acquired resistance was found in 2/9 patients (22%): MET D1228N (n = 1), HGF amplification (n = 1). Potential off-target acquired resistance mechanisms were found in 5/9 pts (44%): KRAS G13V (n = 1), RASA1 S742* (n = 1), MDM2 amplification (n = 2), EGFR amplification (n = 1). Conclusions: Lack of MET expression or RAS pathway activation is associated with poor MET TKI outcomes in MET exon14-altered lung cancers. On-target acquired resistance is found in < 25% of patients; HGF amplification is a novel mechanism. Off-target intrinsic/acquired resistance may be mediated by RAS/MDM2/EGFR pathway activation.

Summary 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.

In a systematic review by Ducic et al in this journal, the authors highlighted how important but underreported nerve injuries are after an abdominoplasty.1 Complications, such as chronic numbness or pain, can have extreme effects on a patient's life. Although the total risk of any nerve injury has been reported to be 1.94%, this is likely an underestimation given that around 7.67% of patients report post-procedural hypoesthesia. The most commonly injured nerve related to surgical incision was the lateral femoral cutaneous nerve (1.36% of all patients). In contrast, there are only a handful of iliohypogastric nerve injuries resulting from abdominoplasties, representing 0.10% of all patients. Most notably, in their literature search, the authors were able to find only two reported cases of iliohypogastric nerve injuries in the literature. We hope to continue to bring attention to this underexplored adverse effect of abdominoplasty. We present the case of a 39-year-old woman with right lower quadrant abdominal pain …

10039 Background: Survival outcomes for older patients with aggressive NHL are disproportionally inferior to those of younger patients. While differences in tumor biology may play a role, older patients are often frail with comorbidities, polypharmacy, and use potentially inappropriate medications (PIM) such as anticholinergics and benzodiazepines. Methods: Using Cox proportional hazard and logistic regression models, we analyzed all aggressive NHL patients age ≥60 treated at our two affiliated hospitals from 2009-2014 to examine the association of polypharmacy and PIM use with progression-free survival (PFS), overall survival (OS), and treatment-related toxicities. Results: In this updated and final analysis, we included 171 patients with complete records from these two hospitals. They share similar demographic, clinical, and laboratory characteristics except for higher International Prognostic Index (IPI) in patients from one hospital. The median age was 70 years (range 65-77). At the time of diagnosis, 46% of patients used more than 4 medications (polypharmacy) and 47% used at least one PIM. Only 43% of patients received first-line chemotherapy of adequate relative dose intensity (>85% dosage), and 65% experienced ≥grade 3 toxicities. Polypharmacy and PIM use were associated with shortened PFS and OS by log-rank test. Most importantly, PIM use remained an independent predictor of PFS, OS, and ≥ grade 3 toxicities in multivariable analyses (Table). Conclusions: This is the first report of significantly adverse survival impacts of polypharmacy and PIM use in older patients with aggressive NHL, presumably from drug-drug interactions that increase toxicities and impair the delivery of adequate chemotherapy dosage. Our findings support the use of evidence-based geriatric principles to guide meticulous medication management to improve outcome disparity for these patients. [Table: see text]

129 Background: Survival outcomes for older patients with aggressive non-Hodgkin’s lymphoma (NHL) are disproportionally inferior to those of younger patients. While differences in tumor biology may play a role, older patients are often frail with comorbidities, polypharmacy, and use potentially inappropriate medications (PIM). Methods: Using Cox proportional hazard and logistic regression models, we retrospectively analyzed all aggressive NHL patients age 60 and older diagnosed and treated at our institution from 2009-2014 to examine the effect of polypharmacy and PIM use on progression-free survival (PFS), overall survival (OS), and treatment-related toxicities. Results: We included 141 patients with evaluable data after excluding patients with incomplete record. The median age was 71 years. At the time of diagnosis, 44% of patients used more than 4 medications and 47% used at least one PIM. During first-line treatment, only 43% of patients received chemotherapy of adequate relative dose intensity (>85% scheduled dose), and 63% experienced grade 3 or greater toxicities. Age, International Prognostic Index, and PIM use correlated with each other. Number of medications (p = 0.005) and PIM use (p < 0.001) were associated with shortened PFS by log-rank test, and PIM use remained a strong independent predictor of PFS in multivariable analysis (HR 1.84, p = 0.005). Number of medications (p = 0.003) and PIM use (p = 0.009) were also associated with shortened OS by log-rank test, although only albumin level predicted OS in multivariable analysis. Most importantly, PIM use was strongly associated with grade 3 or greater toxicities in multivariable analysis (OR 7.4, p = 0.001). Conclusions: We report here for the first time adverse impacts of polypharmacy and PIM use in older patients with aggressive lymphoma. We suggest that drug-drug interactions may significantly impair the delivery of adequate chemotherapy dosage and increase toxicities thus resulting in inferior survival outcome. Our findings support the use of evidence-based geriatric and palliative care principles to guide meticulous medication management to eliminate outcome disparity in older lymphoma patients.

6562Background: Survival outcomes for elderly non-Hodgkin’s lymphoma (NHL) patients are disproportionally inferior to those of younger patients. While their tumor biology may differ, elderly patien...

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.

9042 Background: MET exon 14 alterations occur in ~3% of patients (pts) with NSCLC. Although clinical and genomic features of MET exon 14 mutant (mut) NSCLC are better characterized in the metastatic setting, less is known about early-stage disease for this molecular subtype. Methods: Clinicopathologic and genomic data were collected from patients (pts) with resected stage I-III MET exon 14 mutant NSCLC at the Dana-Farber Cancer Institute (DFCI) and the Memorial Sloan Kettering Cancer Center (MSKCC). We estimated the disease-free survival (DFS) and overall survival (OS) of patients from the date of surgical resection. The prevalence of MET exon 14 mutations in stage I-III NSCLC was assessed using OncoPanel NGS v3.0 at DFCI. Results: The prevalence of MET exon 14 alterations in resected tumors of pts with stage I-III NSCLC at DFCI using Oncopanel v3 was 2.8% (17/613) overall: 2.9% (16/542) in non-squamous and 1.4% (1/71) in squamous histology. We identified 131 pts with resected stage I-III (I = 73, II = 28, III = 30) MET exon 14 mut NSCLC at DFCI (Oncopanel v1-v3) and MSKCC (MSK-IMPACT), with a median age of 71 years (yrs) (range: 43-88). There were no significant differences in sex, smoking status, or type of MET alteration across stages. In stage I resected tumors there was a higher proportion of adenocarcinoma histology compared to stages II and III (p = 0.009). The median harmonized TMB (mTMB) was similar across stages (p = 0.43). Common genomic co-alterations included MET amplification (amp) (5.3%), CDK4/ 6 amp (19.1%), MDM2 amp (35.1%), TP53 mut (17.6%) and CDKN2A/ B loss (9.2%). The median DFS in stage I, II, and III NSCLC was 8.3 yrs (95% CI: 3.1-8.3), 2.6 yrs (95% CI: 1.0-2.6), and 2.1 yrs (95% CI: 0.7-2.7), respectively (p = 0.017). The median OS in stage I, II, and III NSCLC was 9.2 yrs (95% CI: 8.5 -10.5), not reached (NR) (95% CI: NR-NR), and 4.1 yrs (95% CI: 3.6-4.1), respectively (p = 0.052). Concurrent MET amp was independently associated with worse DFS (HR: 4.9, 95% CI: 1.8-13.1; p = 0.002) in multivariate analysis. Conclusions: MET exon 14 mutations are present in 2.8% of resected stage I-III NSCLCs. Given the prevalence of this molecular alteration in early-stage NSCLC, clinical trials exploring the role of adjuvant and neoadjuvant MET targeted therapies in this population may be warranted.