Alexa B. Schrock

Characterization of 298 patients with lung cancer harboring MET Exon 14 skipping alterations

Background: The hepatocyte growth factor receptor gene (MET) exon 14 skipping (METex14) has recently been described a potential driver alteration in lung cancer targetable by mesenchymal‐to‐epithelial transition factor (MET) tyrosine kinase inhibitors (TKIs). Methods: Well‐validated hybrid capture–based comprehensive genomic profiling was performed at the request of individual treating physicians. Results: Of 11,205 lung cancers profiled by comprehensive genomic profiling, 298 (2.7%) carcinomas harbored alterations predicted to cause METex14, including adenosquamous (8.2%), sarcomatoid (7.7%), histologic subtype not otherwise specified (3.0%), adenocarcinoma (2.9%), squamous cell (2.1%), large cell (0.8%), and SCLC (0.2%). Acinar features were present in 24% of the METex14 samples. Six cases (2%) harbored MET Y1003X mutations affecting binding of the MET‐negative regulator, E3 ubiquitin protein ligase. The median age of all patients with METex14 was 73 years (range 43–95) and 60% were female. Concurrent, murine double minute gene (MDM2) amplification, cyclin‐dependent kinase 4 gene (CDK4) amplification, and EGFR amplification were observed in 35%, 21%, and 6.4% of patients with METex14, respectively. KRAS mutation was observed in 3% of cases. Concurrent MET amplification (METamp) (median copy number 10) was identified in 15% of METex14 samples. Significant differences in tumor mutational burden and type of the METex14 alterations were observed between the METamp and non‐METamp samples. Response to MET TKI was observed in both in patients with METamp and in patients without METamp METex14. Conclusion: Diverse targetable METex14 alterations were identified in patients with NSCLC across age groups, including elderly patients, and in all major NSCLC histologic subtypes with an overall frequency of 2.7%. These findings support the use of hybrid capture–based molecular profiling across NSCLC subtypes to identify patients who will potentially benefit from MET TKIs.

Identification of a Novel HIP1-ALK Fusion Variant in Non–Small-Cell Lung Cancer (NSCLC) and Discovery of ALK I1171 (I1171N/S) Mutations in Two ALK-Rearranged NSCLC Patients with Resistance to Alectinib

Huntingtin-interacting protein 1 (HIP1) has recently been identified as a new fusion partner fused to anaplastic lymphoma kinase (ALK) in non-small-cell lung cancer (NSCLC). To date, two variants of HIP1-ALK (H21; A20) and (H28; A20) have been identified in NSCLC. However, the response of patients with NSCLC harboring HIP1-ALK to ALK inhibitors and potential resistance mechanisms to such remain unknown. Here, we report a patient with NSCLC harboring a novel HIP1-ALK fusion variant (H30; A20). This patient and another patient with EML4-ALK variant 3a/b initially responded sequentially to crizotinib and then alectinib, a next-generation ALK inhibitor, but developed acquired resistance to alectinib with the presence of a mutation in amino acid residue 1171 (I1171N and I1171S respectively) located in the hydrophobic regulatory spine (R-spine) of the ALK kinase in both the cases as identified by a comprehensive next-generation sequencing-based assay performed on biopsies of new liver metastases that developed during alectinib treatment.

Comprehensive Genomic Profiling Identifies a Subset of Crizotinib-Responsive ALK-Rearranged Non-Small Cell Lung Cancer Not Detected by Fluorescence In Situ Hybridization

INTRODUCTION For patients with non-small cell lung cancer (NSCLC) to benefit from ALK inhibitors, sensitive and specific detection of ALK genomic rearrangements is needed. ALK break-apart fluorescence in situ hybridization (FISH) is the U.S. Food and Drug Administration approved and standard-of-care diagnostic assay, but identification of ALK rearrangements by other methods reported in NSCLC cases that tested negative for ALK rearrangements by FISH suggests a significant false-negative rate. We report here a large series of NSCLC cases assayed by hybrid-capture-based comprehensive genomic profiling (CGP) in the course of clinical care. MATERIALS AND METHODS Hybrid-capture-based CGP using next-generation sequencing was performed in the course of clinical care of 1,070 patients with advanced lung cancer. Each tumor sample was evaluated for all classes of genomic alterations, including base-pair substitutions, insertions/deletions, copy number alterations and rearrangements, as well as fusions/rearrangements. RESULTS A total of 47 patients (4.4%) were found to harbor ALK rearrangements, of whom 41 had an EML4-ALK fusion, and 6 had other fusion partners, including 3 previously unreported rearrangement events: EIF2AK-ALK, PPM1B-ALK, and PRKAR1A-ALK. Of 41 patients harboring ALK rearrangements, 31 had prior FISH testing results available. Of these, 20 were ALK FISH positive, and 11 (35%) were ALK FISH negative. Of the latter 11 patients, 9 received crizotinib based on the CGP results, and 7 achieved a response with median duration of 17 months. CONCLUSION Comprehensive genomic profiling detected canonical ALK rearrangements and ALK rearrangements with noncanonical fusion partners in a subset of patients with NSCLC with previously negative ALK FISH results. In this series, such patients had durable responses to ALK inhibitors, comparable to historical response rates for ALK FISH-positive cases. IMPLICATIONS FOR PRACTICE Comprehensive genomic profiling (CGP) that includes hybrid capture and specific baiting of intron 19 of ALK is a highly sensitive, alternative method for identification of drug-sensitive ALK fusions in patients with non-small cell lung cancer (NSCLC) who had previously tested negative using standard ALK fluorescence in situ hybridization (FISH) diagnostic assays. Given the proven benefit of treatment with crizotinib and second-generation ALK inhibitors in patients with ALK fusions, CGP should be considered in patients with NSCLC, including those who have tested negative for other alterations, including negative results using ALK FISH testing.

Non-V600BRAF Mutations Define a Clinically Distinct Molecular Subtype of Metastatic Colorectal Cancer

Purpose Molecular diagnostic testing has become an integral part of the evaluation of patients with metastatic colorectal cancer (CRC). Expanded mutational testing, such as next-generation sequencing (NGS), often identifies mutations with unclear clinical or prognostic implications. One such example is BRAF mutations that occur outside of codon 600 (non-V600 BRAF mutations). Methods We conducted this multicenter, retrospective cohort study to characterize the clinical, pathologic, and survival implications of non-V600 BRAF mutations in metastatic CRC. We pooled patients in whom non-V600 BRAF mutations were identified from NGS databases at three large molecular genetics reference laboratories. Results A total of 9,643 patients with metastatic CRC underwent NGS testing. We identified 208 patients with non-V600 BRAF mutations, which occurred in 2.2% of all patients tested and accounted for 22% of all BRAF mutations identified. Cancers with non-V600 BRAF mutations, compared with cancers with V600E BRAF (V600E BRAF) mutations, were found in patients who were significantly younger (58 v 68 years, respectively), fewer female patients (46% v 65%, respectively), and patients who had fewer high-grade tumors (13% v 64%, respectively) or right-sided primary tumors (36% v 81%, respectively). Median overall survival was significantly longer in patients with non-V600 BRAF-mutant metastatic CRC compared with those with both V600E BRAF-mutant and wild-type BRAF metastatic CRC (60.7 v 11.4 v 43.0 months, respectively; P < .001). In multivariable analysis, non-V600 BRAF mutation was independently associated with improved overall survival (hazard ratio, 0.18; P < .001). Conclusion Non-V600 BRAF mutations occur in approximately 2.2% of patients with metastatic CRC and define a clinically distinct subtype of CRC with an excellent prognosis.

Comprehensive genomic profiling of anal squamous cell carcinoma reveals distinct genomically defined classes

BACKGROUND Squamous cell cancers of the anal canal (ASCC) are increasing in frequency and lack effective therapies for advanced disease. Although an association with human papillomavirus (HPV) has been established, little is known about the molecular characterization of ASCC. A comprehensive genomic analysis of ASCC was undertaken to identify novel genomic alterations (GAs) that will inform therapeutic choices for patients with advanced disease. PATIENTS AND METHODS Hybrid-capture-based next-generation sequencing of exons from 236 cancer-related genes and intronic regions from 19 genes commonly rearranged in cancer was performed on 70 patients with ASCC. HPV status was assessed by aligning tumor sequencing reads to HPV viral genomes. GAs were identified using an established algorithm and correlated with HPV status. RESULTS Sixty-one samples (87%) were HPV-positive. A mean of 3.5 GAs per sample was identified. Recurrent alterations in phosphoinositol-3-kinase pathway (PI3K/AKT/mTOR) genes including amplifications and homozygous deletions were present in 63% of cases. Clinically relevant GAs in genes involved in DNA repair, chromatin remodeling, or receptor tyrosine kinase signaling were observed in 30% of cases. Loss-of-function mutations in TP53 and CDKN2A were significantly enhanced in HPV-negative cases (P < 0.0001). CONCLUSIONS This is the first comprehensive genomic analysis of ASCC, and the results suggest new therapeutic approaches. Differing genomic profiles between HPV-associated and HPV-negative ASCC warrants further investigation and may require novel therapeutic and preventive strategies.

Emergence of Preexisting MET Y1230C Mutation as a Resistance Mechanism to Crizotinib in NSCLC with MET Exon 14 Skipping

Introduction: MET proto‐oncogene, receptor tyrosine kinase gene exon 14 skipping (METex14) alterations represent a unique subset of oncogenic drivers in NSCLC. Preliminary clinical activity of crizotinib against METex14‐positive NSCLC has been reported. The full spectrum of resistance mechanisms to crizotinib in METex14‐positive NSCLC remains to be identified. Methods: Hybrid capture–based comprehensive genomic profiling performed on a tumor specimen obtained at diagnosis, and a hybrid capture–based assay of circulating tumor DNA (ctDNA) at the time of progression during crizotinib treatment was assessed in a pairwise fashion. Results: A METex14 alteration (D1010H) was detected in the pretreatment tumor biopsy specimen, as was MET proto‐oncogene, receptor tyrosine kinase (MET) Y1230C, retrospectively, at very low frequency (0.3%). After a confirmed response during crizotinib treatment for 13 months followed by progression, both MET proto‐oncogene, receptor tyrosine kinase gene Y1230C and D1010H were detected prospectively in the ctDNA. Conclusion: Emergence of the preexisting MET Y1230C likely confers resistance to crizotinib in this case of METex14‐positive NSCLC. Existence of pretreatment MET Y1230C may eventually modulate the response of METex14‐positive NSCLC to type I MET tyrosine kinase inhibitors. Noninvasive plasma‐based ctDNA assays can provide a convenient method to detect resistance mutations in patients with previously known driver mutations.

Impact of EML4-ALK Variant on Resistance Mechanisms and Clinical Outcomes in ALK-Positive Lung Cancer

Purpose Advanced anaplastic lymphoma kinase ( ALK) fusion-positive non-small-cell lung cancers (NSCLCs) are effectively treated with ALK tyrosine kinase inhibitors (TKIs). However, clinical outcomes in these patients vary, and the benefit of TKIs is limited as a result of acquired resistance. Emerging data suggest that the ALK fusion variant may affect clinical outcome, but the molecular basis for this association is unknown. Patients and Methods We identified 129 patients with ALK-positive NSCLC with known ALK variants. ALK resistance mutations and clinical outcomes on ALK TKIs were retrospectively evaluated according to ALK variant. A Foundation Medicine data set of 577 patients with ALK-positive NSCLC was also examined. Results The most frequent ALK variants were EML4-ALK variant 1 in 55 patients (43%) and variant 3 in 51 patients (40%). We analyzed 77 tumor biopsy specimens from patients with variants 1 and 3 who had progressed on an ALK TKI. ALK resistance mutations were significantly more common in variant 3 than in variant 1 (57% v 30%; P = .023). In particular, ALK G1202R was more common in variant 3 than in variant 1 (32% v 0%; P < .001). Analysis of the Foundation Medicine database revealed similar associations of variant 3 with ALK resistance mutation and with G1202R ( P = .010 and .015, respectively). Among patients treated with the third-generation ALK TKI lorlatinib, variant 3 was associated with a significantly longer progression-free survival than variant 1 (hazard ratio, 0.31; 95% CI, 0.12 to 0.79; P = .011). Conclusion Specific ALK variants may be associated with the development of ALK resistance mutations, particularly G1202R, and provide a molecular link between variant and clinical outcome. ALK variant thus represents a potentially important factor in the selection of next-generation ALK inhibitors.

Identification of NTRK fusions in pediatric mesenchymal tumors

NTRK fusions are known oncogenic drivers and have recently been effectively targeted by investigational agents in adults. We sought to assess the frequency of NTRK fusions in a large series of pediatric and adolescent patients with advanced cancers.

ROS1 Fusions Rarely Overlap with Other Oncogenic Drivers in Non–Small Cell Lung Cancer

Introduction: Chromosomal rearrangements involving the gene ROS1 define a distinct molecular subset of NSCLCs with sensitivity to ROS1 inhibitors. Recent reports have suggested a significant overlap between ROS1 fusions and other oncogenic driver alterations, including mutations in EGFR and KRAS. Methods: We identified patients at our institution with ROS1‐rearranged NSCLC who had undergone testing for genetic alterations in additional oncogenes, including EGFR, KRAS, and anaplastic lymphoma receptor tyrosine kinase gene (ALK). Clinicopathologic features and genetic testing results were reviewed. We also examined a separate database of ROS1‐rearranged NSCLCs identified through the commercial FoundationOne assay (Foundation Medicine, Cambridge, MA). Results: Among 62 patients with ROS1‐rearranged NSCLC evaluated at our institution, none harbored concurrent ALK fusions (0%) or EGFR activating mutations (0%). KRAS mutations were detected in two cases (3.2%), one of which harbored a concurrent noncanonical KRAS I24N mutation of unknown biological significance. In a separate ROS1 fluorescence in situ hybridization–positive case, targeted sequencing failed to confirm a ROS1 fusion but instead identified a KRAS G13D mutation. No concurrent mutations in B‐Raf proto‐oncogene, serine/threonine kinase gene (BRAF), erb‐b2 receptor tyrosine kinase 2 gene (ERBB2), phosphatidylinositol‐4,5‐bisphosphate 3‐kinase catalytic subunit alpha gene (PIK3CA), AKT/serine threonine kinase 1 gene (AKT1), or mitogen‐activated protein kinase kinase 1 gene (MAP2K1) were detected. Analysis of an independent data set of 166 ROS1‐rearranged NSCLCs identified by FoundationOne demonstrated rare cases with co‐occurring driver mutations in EGFR (one of 166) and KRAS (three of 166) and no cases with co‐occurring ROS1 and ALK rearrangements. Conclusions: ROS1 rearrangements rarely overlap with alterations in EGFR, KRAS, ALK, or other targetable oncogenes in NSCLC.

HER2 Transmembrane Domain (TMD) Mutations (V659/G660) That Stabilize Homo- and Heterodimerization Are Rare Oncogenic Drivers in Lung Adenocarcinoma That Respond to Afatinib

Introduction: Erb‐b2 receptor tyrosine kinase (HER2) transmembrane domain (TMD) mutations (HER2V659E, HER2G660D) have previously been identified in lung adenocarcinomas, but their frequency and clinical significance is unknown. Methods: We prospectively analyzed 8551 consecutive lung adenocarcinomas using hybrid capture–based comprehensive genomic profiling (CGP) at the request of the individual treating physicians for the purpose of making therapy decisions. Results: We identified 15 cases (0.18%) of HER2 TMD mutations (HER2V659E/D, HER2G660D) through CGP of 8551 lung adenocarcinomas. HER2 TMD mutations were mutually exclusive from HER2 kinase domain mutations and other oncogenic drivers in lung adenocarcinoma. Only two cases with HER2 TMD mutations (13%) had concurrent Erb‐b2 receptor tyrosine kinase 2 gene (HER2) amplification. Structural analysis of HER2 TMD association revealed that mutations at positions V659 and G660 to the highly polar residues glutamic acid, aspartic acid, or arginine should stabilize homodimerization and heterodimerization of HER2 in the active conformation. Treatment with afatinib, a pan‐HER inhibitor, resulted in durable clinical response in three of four patients with lung adenocarcinoma, with two harboring HER2V659E and one with double HER2V659E/G660R mutations. HER2 TMD mutations (V659 and G660) are found in other non‐NSCLC malignancies, and analogous TMD mutations are also found in EGFR, HER3, and HER4. Conclusion: HER2 TMD mutations represent rare but distinct targetable driver mutations in lung adenocarcinoma. CGP capable of detecting diverse HER2 alterations, including HER2 TMD mutations, should be broadly adopted to identify all patients who may benefit from HER2‐targeted therapies.