TRK fusions are found in a variety of cancer types, lead to oncogenic addiction, and strongly predict tumor-agnostic efficacy of TRK inhibition
. With the recent approval of the first selective TRK ...inhibitor, larotrectinib, for patients with any TRK-fusion-positive adult or pediatric solid tumor, to identify mechanisms of treatment failure after initial response has become of immediate therapeutic relevance. So far, the only known resistance mechanism is the acquisition of on-target TRK kinase domain mutations, which interfere with drug binding and can potentially be addressable through second-generation TRK inhibitors
. Here, we report off-target resistance in patients treated with TRK inhibitors and in patient-derived models, mediated by genomic alterations that converge to activate the mitogen-activated protein kinase (MAPK) pathway. MAPK pathway-directed targeted therapy, administered alone or in combination with TRK inhibition, re-established disease control. Experimental modeling further suggests that upfront dual inhibition of TRK and MEK may delay time to progression in cancer types prone to the genomic acquisition of MAPK pathway-activating alterations. Collectively, these data suggest that a subset of patients will develop off-target mechanisms of resistance to TRK inhibition with potential implications for clinical management and future clinical trial design.
Purpose Human epidermal growth factor receptor 2 ( HER2, ERBB2)-activating mutations occur in 2% of lung cancers. We assessed the activity of ado-trastuzumab emtansine, a HER2-targeted antibody-drug ...conjugate, in a cohort of patients with HER2-mutant lung cancers as part of a phase II basket trial. Patients and Methods Patients received ado-trastuzumab emtansine at 3.6 mg/kg intravenously every 3 weeks until progression. The primary end point was overall response rate using Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1. A Simon two-stage optimal design was used. Other end points included progression-free survival and toxicity. HER2 testing was performed on tumor tissue by next generation sequencing, fluorescence in situ hybridization, immunohistochemistry, and protein mass spectrometry. Results We treated 18 patients with advanced HER2-mutant lung adenocarcinomas. The median number of prior systemic therapies was two (range, zero to four prior therapies). The partial response rate was 44% (95% CI, 22% to 69%), meeting the primary end point. Responses were seen in patients with HER2 exon 20 insertions and point mutations in the kinase, transmembrane, and extracellular domains. Concurrent HER2 amplification was observed in two patients. HER2 immunohistochemistry ranged from 0 to 2+ and did not predict response, and responders had low HER2 protein expression measured by mass spectrometry. The median progression-free survival was 5 months (95% CI, 3 to 9 months). Toxicities included grade 1 or 2 infusion reactions, thrombocytopenia, and elevated hepatic transaminases. No patient stopped therapy as a result of toxicity or died on study. Conclusion Ado-trastuzumab emtansine is an active agent in patients with HER2-mutant lung cancers. This is the first positive trial in this molecular subset of lung cancers. Further use and study of this agent are warranted.
Invasive mucinous adenocarcinoma (IMA) is a unique subtype of lung adenocarcinoma, characterized genomically by frequent
mutations or specific gene fusions, most commonly involving
. Comprehensive ...analysis of a large series of IMAs using broad DNA- and RNA-sequencing methods is still lacking, and it remains unclear whether molecular subtypes of IMA differ clinicopathologically.
A total of 200 IMAs were analyzed by 410-gene DNA next-generation sequencing (MSK-IMPACT;
= 136) or hotspot 8-oncogene genotyping (
= 64). Driver-negative cases were further analyzed by 62-gene RNA sequencing (MSK-Fusion) and those lacking fusions were further tested by whole-exome sequencing and whole-transcriptome sequencing (WTS).
Combined MSK-IMPACT and MSK-Fusion testing identified mutually exclusive driver alterations in 96% of IMAs, including
mutations (76%),
fusions (7%),
alterations (6%), and other less common events. In addition, WTS identified a novel
fusion (
-
). Overall, targetable gene fusions were identified in 51% of
wild-type IMAs, leading to durable responses to targeted therapy in some patients. Compared with
-mutant IMAs,
-rearranged tumors exhibited several more aggressive characteristics, including worse recurrence-free survival (
< 0.0001).
This is the largest molecular study of IMAs to date, where we demonstrate the presence of a major oncogenic driver in nearly all cases. This study is the first to document more aggressive characteristics of
-rearranged IMAs,
as the third most common alteration, and a novel
fusion in these tumors. Comprehensive molecular testing of
wild-type IMAs that includes fusion testing is essential, given the high prevalence of alterations with established and investigational targeted therapies in this subset.
The identification of specific genetic alterations as key oncogenic drivers and the development of targeted therapies are together transforming clinical oncology and creating a pressing need for ...increased breadth and throughput of clinical genotyping. Next-generation sequencing assays allow the efficient and unbiased detection of clinically actionable mutations. To enable precision oncology in patients with solid tumors, we developed Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets (MSK-IMPACT), a hybridization capture-based next-generation sequencing assay for targeted deep sequencing of all exons and selected introns of 341 key cancer genes in formalin-fixed, paraffin-embedded tumors. Barcoded libraries from patient-matched tumor and normal samples were captured, sequenced, and subjected to a custom analysis pipeline to identify somatic mutations. Sensitivity, specificity, reproducibility of MSK-IMPACT were assessed through extensive analytical validation. We tested 284 tumor samples with previously known point mutations and insertions/deletions in 47 exons of 19 cancer genes. All known variants were accurately detected, and there was high reproducibility of inter- and intrarun replicates. The detection limit for low-frequency variants was approximately 2% for hotspot mutations and 5% for nonhotspot mutations. Copy number alterations and structural rearrangements were also reliably detected. MSK-IMPACT profiles oncogenic DNA alterations in clinical solid tumor samples with high accuracy and sensitivity. Paired analysis of tumors and patient-matched normal samples enables unambiguous detection of somatic mutations to guide treatment decisions.
mutations define a subset of metastatic breast cancers with a unique mechanism of oncogenic addiction to HER2 signaling. We explored activity of the irreversible pan-HER kinase inhibitor neratinib, ...alone or with fulvestrant, in 81 patients with
-mutant metastatic breast cancer. Overall response rate was similar with or without estrogen receptor (ER) blockade. By comparison, progression-free survival and duration of response appeared longer in ER
patients receiving combination therapy, although the study was not designed for direct comparison. Preexistent concurrent activating
or
alterations were associated with poor treatment outcome. Similarly, acquisition of multiple
-activating events, as well as gatekeeper alterations, were observed at disease progression in a high proportion of patients deriving clinical benefit from neratinib. Collectively, these data define
mutations as a therapeutic target in breast cancer and suggest that coexistence of additional HER signaling alterations may promote both
and acquired resistance to neratinib. SIGNIFICANCE:
mutations define a targetable breast cancer subset, although sensitivity to irreversible HER kinase inhibition appears to be modified by the presence of concurrent activating genomic events in the pathway. These findings have implications for potential future combinatorial approaches and broader therapeutic development for this genomically defined subset of breast cancer.
.
Broad and deep tumour genome sequencing has shed new light on tumour heterogeneity and provided important insights into the evolution of metastases arising from different clones. There is an ...additional layer of complexity, in that tumour evolution may be influenced by selective pressure provided by therapy, in a similar fashion to that occurring in infectious diseases. Here we studied tumour genomic evolution in a patient (index patient) with metastatic breast cancer bearing an activating PIK3CA (phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha, PI(3)Kα) mutation. The patient was treated with the PI(3)Kα inhibitor BYL719, which achieved a lasting clinical response, but the patient eventually became resistant to this drug (emergence of lung metastases) and died shortly thereafter. A rapid autopsy was performed and material from a total of 14 metastatic sites was collected and sequenced. All metastatic lesions, when compared to the pre-treatment tumour, had a copy loss of PTEN (phosphatase and tensin homolog) and those lesions that became refractory to BYL719 had additional and different PTEN genetic alterations, resulting in the loss of PTEN expression. To put these results in context, we examined six other patients also treated with BYL719. Acquired bi-allelic loss of PTEN was found in one of these patients, whereas in two others PIK3CA mutations present in the primary tumour were no longer detected at the time of progression. To characterize our findings functionally, we examined the effects of PTEN knockdown in several preclinical models (both in cell lines intrinsically sensitive to BYL719 and in PTEN-null xenografts derived from our index patient), which we found resulted in resistance to BYL719, whereas simultaneous PI(3)K p110β blockade reverted this resistance phenotype. We conclude that parallel genetic evolution of separate metastatic sites with different PTEN genomic alterations leads to a convergent PTEN-null phenotype resistant to PI(3)Kα inhibition.
Renal cell carcinomas with unclassified histology (uRCC) constitute a significant portion of aggressive non-clear cell renal cell carcinomas that have no standard therapy. The oncogenic drivers in ...these tumours are unknown. Here we perform a molecular analysis of 62 high-grade primary uRCC, incorporating targeted cancer gene sequencing, RNA sequencing, single-nucleotide polymorphism array, fluorescence in situ hybridization, immunohistochemistry and cell-based assays. We identify recurrent somatic mutations in 29 genes, including NF2 (18%), SETD2 (18%), BAP1 (13%), KMT2C (10%) and MTOR (8%). Integrated analysis reveals a subset of 26% uRCC characterized by NF2 loss, dysregulated Hippo-YAP pathway and worse survival, whereas 21% uRCC with mutations of MTOR, TSC1, TSC2 or PTEN and hyperactive mTORC1 signalling are associated with better clinical outcome. FH deficiency (6%), chromatin/DNA damage regulator mutations (21%) and ALK translocation (2%) distinguish additional cases. Altogether, this study reveals distinct molecular subsets for 76% of our uRCC cohort, which could have diagnostic and therapeutic implications.
Abstract Background Metastatic renal cell carcinoma (RCC) patients are commonly treated with vascular endothelial growth factor (VEGF) inhibitors or mammalian target of rapamycin inhibitors. ...Correlations between somatic mutations and first-line targeted therapy outcomes have not been reported on a randomized trial. Objective To evaluate the relationship between tumor mutations and treatment outcomes in RECORD-3, a randomized trial comparing first-line everolimus (mTOR inhibitor) followed by sunitinib (VEGF inhibitor) at progression with the opposite sequence in 471 metastatic RCC patients. Design, setting, and participants Targeted sequencing of 341 cancer genes at ∼540× coverage was performed on available tumor samples from 258 patients; 220 with clear cell histology (ccRCC). Outcome measurements and statistical analysis Associations between somatic mutations and median first-line progression free survival (PFS1L) and overall survival were determined in metastatic ccRCC using Cox proportional hazards models and log-rank tests. Results and limitations Prevalent mutations (≥ 10%) were VHL (75%), PBRM1 (46%), SETD2 (30%), BAP1 (19%), KDM5C (15%), and PTEN (12%). With first-line everolimus, PBRM1 and BAP1 mutations were associated with longer (median 95% confidence interval {CI} 12.8 8.1, 18.4 vs 5.5 3.1, 8.4 mo) and shorter (median 95% CI 4.9 2.9, 8.1 vs 10.5 7.3, 12.9 mo) PFS1L, respectively. With first-line sunitinib, KDM5C mutations were associated with longer PFS1L (median 95% CI of 20.6 12.4, 27.3 vs 8.3 7.8, 11.0 mo). Molecular subgroups of metastatic ccRCC based on PBRM1 , BAP1 , and KDM5C mutations could have predictive values for patients treated with VEGF or mTOR inhibitors. Most tumor DNA was obtained from primary nephrectomy samples (94%), which could impact correlation statistics. Conclusions PBRM1 , BAP1 , and KDM5C mutations impact outcomes of targeted therapies in metastatic ccRCC patients. Patient summary Large-scale genomic kidney cancer studies reported novel mutations and heterogeneous features among individual tumors, which could contribute to varied clinical outcomes. We demonstrated correlations between somatic mutations and treatment outcomes in clear cell renal cell carcinoma, supporting the value of genomic classification in prospective studies.
Hereditary leiomyomatosis and renal cell carcinoma (HLRCC) syndrome is an autosomal dominant disorder in which germline mutations of fumarate hydratase (FH) gene confer an increased risk of cutaneous ...and uterine leiomyomas and renal cancer. HLRCC-associated renal cancer is highly aggressive and frequently presents as a solitary mass. We reviewed the clinicopathologic features of 9 patients with renal tumors presenting as sporadic cases but who were later proven to have FH germline mutations. Histologically, all tumors showed mixed architectural patterns, with papillary as the dominant pattern in only 3 cases. Besides papillary, tubular, tubulopapillary, solid, and cystic elements, 6 of 9 tumors contained collecting duct carcinoma-like areas with infiltrating tubules, nests, or individual cells surrounded by desmoplastic stroma. Prominent tubulocystic carcinoma-like component and sarcomatoid differentiation were identified. Although all tumors exhibited the proposed hallmark of HLRCC (large eosinophilic nucleolus surrounded by a clear halo), this feature was often not uniformly present throughout the tumor. Prior studies have shown that a high level of fumarate accumulated in HLRCC tumor cells causes aberrant succination of cellular proteins by forming a stable chemical modification, S-(2-succino)-cysteine (2SC), which can be detected by immunohistochemistry. We thus explored the utility of detecting 2SC by immunohistochemistry in the differential diagnosis of HLRCC tumors and other high-grade renal tumors and investigated the correlation between 2SC staining and FH molecular alterations. All confirmed HLRCC tumors demonstrated diffuse and strong nuclear and cytoplasmic 2SC staining, whereas all clear cell (184/184, 100%), most high-grade unclassified (93/97, 96%), and the large majority of "type 2" papillary (35/45, 78%) renal cell carcinoma cases showed no 2SC immunoreactivity. A subset of papillary (22%) and rare unclassified (4%) tumors showed patchy or diffuse cytoplasmic staining without nuclear labeling, unlike the pattern seen with confirmed HLRCC tumors. Sequencing revealed no germline or somatic FH alterations in 14 tumors that either exhibited only cytoplasmic 2SC staining (n=5) or were negative for 2SC (n=9), despite their HLRCC-like morphologic features. Our results emphasize the pivotal role of pathologic examination in the diagnosis of HLRCC patients and indicate immunohistochemical detection of 2SC as a useful ancillary tool in the differentiation of HLRCC renal tumors from other high-grade renal cell carcinomas.
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