Ongoing Clinical Trials and Future Research Scenarios of Circulating Tumor DNA for the Treatment of Metastatic Colorectal Cancer.

Liquid biopsy using circulating tumor DNA (ctDNA) has emerged as a minimally invasive, timely approach to provide molecular diagnosis and monitor tumor evolution in patients with cancer. Since the molecular landscape of metastatic colorectal cancer (mCRC) is substantially heterogeneous and dynamic over space and time, ctDNA holds significant advantages as a biomarker for this disease. Numerous studies have demonstrated that ctDNA broadly recapitulates the molecular profile of the primary tumor and metastases, and have mainly focused on the genotyping of RAS and BRAF, that is propaedeutic for anti-EGFR treatment selection. However, ctDNA soon broadened its scope towards the assessment of early tumor response, as well as the identification of drug resistance biomarkers to drive potential molecular actionability. In this review article, we provide an overview of the current state-of-the-art of this methodology and its applications, focusing on ongoing clinical trials that employ ctDNA to prospectively guide treatment in patients with mCRC.

Clinicopathological characterisation of MTAP alterations in gastrointestinal cancers.

BACKGROUND: Methylthioadenosine phosphorylase (MTAP) is an essential metabolic enzyme in the purine and methionine salvage pathway. In cancer, MTAP gene copy number loss (MTAP loss) confers a selective dependency on the related protein arginine methyltransferase 5. The impact of MTAP alterations in gastrointestinal (GI) cancers remains unknown although hypothetically druggable. Here, we aim to investigate the prevalence, clinicopathological features and prognosis of MTAP loss GI cancers. METHODS: Cases with MTAP alterations were retrieved from The Cancer Genome Atlas (TCGA) and a real-world cohort of GI cancers profiled by next-generation sequencing. If MTAP alterations other than loss were found, immunohistochemistry was performed. Finally, we set a case-control study to assess MTAP loss prognostic impact. RESULTS: Findings across the TCGA dataset (N=1363 patients) and our cohort (N=508) were consistent. Gene loss was the most common MTAP alteration (9.4%), mostly co-occurring with CDKN2A/B loss (97.7%). Biliopancreatic and gastro-oesophageal cancers had the highest prevalence of MTAP loss (20.5% and 12.7%, respectively), being mostly microsatellite stable (99.2%). In colorectal cancer, MTAP loss was rare (1.1%), while most MTAP alterations were mutations (5/7, 71.4%); among the latter, only MTAP-CDKN2B truncation led to protein loss, thus potentially actionable. MTAP loss did not confer worse prognosis. CONCLUSIONS: MTAP alterations are found in 5%-10% of GI cancers, most frequently biliopancreatic and gastro-oesophageal. MTAP loss is the most common alteration, identified almost exclusively in MSS, CDKN2A/B loss, upper-GI cancers. Other MTAP alterations were found in colorectal cancer, but unlikely to cause protein loss and drug susceptibility.

Young-onset colorectal cancer: treatment-related nausea, vomiting and diarrhoea.

OBJECTIVES: Early-onset colorectal cancer (EO-CRC) incidence is increasing, raising a clinical challenge. Clinicians tend to treat EO-CRC patients with more intensive regimens despite the lack of survival benefits, based on an age-related bias. Limited evidence is available regarding treatment-related toxicities in this peculiar subset of patients. METHODS: We performed a literature search in MEDLINE/PubMed, EMBASE and Scopus, looking for reporting of nausea, vomiting and diarrhoea occurring in patients with EO-CRC, defined by age lower than 50 years old at initial diagnosis, while receiving anticancer treatment. RESULTS: 2318 records were screened and 9 full-text articles were considered eligible for inclusion for a total of 59 783 patients (of whom 8681 EO-CRC patients). We found nausea and vomiting occurring at higher incidence among EO-CRC compared with older patients, while no difference was reported as for diarrhoea. Peritoneal involvement, age younger than 40, female gender, suboptimal adherence to guidelines and oxaliplatin might represent potential risk factors for increased nausea and vomiting in patients with EO-CRC. CONCLUSION: EO-CRC patients experience more nausea and vomiting but equal or less diarrhoea compared with older patients. Adherence to clinical guidelines is recommended, and more data are warranted to assess if an enhanced antiemetic approach might be required, particularly in case of specific risk factors.

Circulating Tumor DNA to Drive Treatment in Metastatic Colorectal Cancer.

In the evolving molecular treatment landscape of metastatic colorectal cancer (mCRC), the identification of druggable alterations is pivotal to achieve the best therapeutic opportunity for each patient. Because the number of actionable targets is expanding, there is the need to timely detect their presence or emergence to guide the choice of different available treatment options. Liquid biopsy, through the analysis of circulating tumor DNA (ctDNA), has proven safe and effective as a complementary method to address cancer evolution while overcoming the limitations of tissue biopsy. Even though data are accumulating regarding the potential for ctDNA-guided treatments applied to targeted agents, still major gaps in knowledge exist as for their application to different areas of the continuum of care. In this review, we recapitulate how ctDNA information could be exploited to drive different targeted treatment strategies in mCRC patients, by refining molecular selection before treatment by addressing tumor heterogeneity beyond tumor tissue biopsy; longitudinally monitoring early-tumor response and resistance mechanisms to targeted agents, potentially leading to tailored, molecular-driven, therapeutic options; guiding the molecular triage towards rechallenge strategies with anti-EGFR agents, suggesting the best time for retreatment; and providing opportunities for an "enhanced rechallenge" through additional treatments or combos aimed at overcoming acquired resistance. Besides, we discuss future perspectives concerning the potential role of ctDNA to fine-tune investigational strategies such as immuno-oncology.

Corrigendum: Case report: MAP2K1 K57N mutation is associated with primary resistance to anti-EGFR monoclonal antibodies in metastatic colorectal cancer.

[This corrects the article DOI: 10.3389/fonc.2022.1030232.].

Case Report: MAP2K1 K57N mutation is associated with primary resistance to anti-EGFR monoclonal antibodies in metastatic colorectal cancer.

Background: We aim to identify the prevalence and the role of the MAP2K1 K57N mutation in predicting resistance to anti-EGFR agents in metastatic colorectal cancer (mCRC) patients. Methods: We retrospectively reviewed tumor-based next generation sequencing (NGS) results from mCRC patients screened for enrollment in the GO40872/STARTRK-2 clinical trial between July 2019 and March 2021. Then, in patients harboring microsatellite stable (MSS) RAS and BRAF wild-type MAP2K1 mutant mCRC, we reviewed outcome to treatment with anti-EGFR monoclonal antibodies. Results: A total of 246 mCRC patients were screened. Most of them, 215/220 (97.7%), were diagnosed with MSS mCRC and 112/215 (52.1%) with MSS, RAS and BRAF wild-type mCRC. Among the latter, 2/112 (1.8%) had MAP2K1 K57N mutant mCRC and both received anti-EGFR monotherapy as third line treatment. In both patients, MAP2K1 K57N mutant tumors proved primary resistant to anti-EGFR agent panitumumab monotherapy. Of interest, one of these patients was treated with anti-EGFR agents three times throughout his course of treatment, achieving some clinical benefit only when associated with other cytotoxic agents (FOLFOX or irinotecan). Conclusion: We verified in a clinical real-world setting that MAP2K1 K57N mutation is a resistance mechanism to anti-EGFR agents in mCRC. Thus, we suggest avoiding the administration of these drugs to MSS RAS and BRAF wild-type MAP2K1 N57K mutant mCRC.

Efficacy of Retreatment with Oxaliplatin-Based Regimens in Metastatic Colorectal Cancer Patients: The RETROX-CRC Retrospective Study.

BACKGROUND: oxaliplatin with fluoropyrimidine is a "mainstay" regarding the upfront treatment of metastatic colorectal cancer (mCRC). In contrast, the efficacy and safety of oxaliplatin-based regimens in late-care settings have been poorly reported. METHODS: we identified a real-world mCRC patient cohort who were re-treated with oxaliplatin, and in which clinicopathological features were retrospectively analyzed to identify efficacy-predictive determinants (RETROX-CRC study). RESULTS: of 2606 patients, 119 fulfilled the eligibility criteria. Oxaliplatin retreatment response rate (RR) and disease control rate (DCR) were 21.6% (CI 14.4-31.0%), and 57.8% (CI 47.7-67.4). A trend towards better RR and DCR was observed among patients who had first oxaliplatin in an adjuvant setting; a poorer outcome was observed if two or more intervening treatments were delivered. Median progression-free survival (PFS) was 5.1 months (95%CI 4.3-6.1), reducing to 4.0 months (95%CI 3.07-5.13) if oxaliplatin was readministered beyond third-line (HR 2.02; 1.25-3.25; p = 0.004). Safety data were retrieved in 65 patients (54.6%); 18.5% (12/65) and 7.7% (5/65) had G3-4 toxicities. Toxicities led to discontinuation in 34/119 (28.6%). CONCLUSIONS: oxaliplatin retreatment produced further RR in around one-fifth of patients and DCR 57.8%. Efficacy decreased in more pre-treated patients and around one-third of patients discontinued treatment due to adverse events. Translational studies improving patient selection are warranted.

Liquid Biopsy for Prognosis and Treatment in Metastatic Colorectal Cancer: Circulating Tumor Cells vs Circulating Tumor DNA.

Liquid biopsy recently gained widespread attention as a noninvasive alternative/complementary technique to tissue biopsy in patients with cancer. As technological advances have improved both feasibility and turnaround time, liquid biopsy has expanded tumor molecular analysis with acknowledgement of both spatial and temporal heterogeneity, overcoming many limitations of traditional tissue biopsy. Because of its diagnostic, prognostic, and predictive value, liquid biopsy has been extensively studied also in metastatic colorectal cancer. Indeed, as personalized medicine establishes its role in cancer treatment, genetic biomarkers unveiling the emergence of early resistance are needed. Among the wide variety of tumor analytes amenable to collection, circulating DNA and circulating tumor cells are the most adopted approaches, and both carry clinical relevance in colorectal cancer. However, few studies focused on comparing feasibility between these two approaches. In this review, we discuss the potential implications of liquid biopsy in metastatic colorectal cancer, assessing the advantages and drawbacks of circulating DNA and circulating tumor cells, and highlighting the most relevant trials for clinical practice.

The Evolutionary Landscape of Treatment for BRAFV600E Mutant Metastatic Colorectal Cancer.

The BRAFV600E mutation is found in 8-10% of metastatic colorectal cancer (mCRC) patients and it is recognized as a poor prognostic factor with a median overall survival inferior to 20 months. At present, besides immune checkpoint inhibitors (CPIs) for those tumors with concomitant MSI-H status, recommended treatment options include cytotoxic chemotherapy + anti-VEGF in the first line setting, and a combination of EGFR and a BRAF inhibitor (cetuximab plus encorafenib) in second line. However, even with the latter targeted approach, acquired resistance limits the possibility of more than an incremental benefit and survival is still dismal. In this review, we discuss current treatment options for this subset of patients and perform a systematic review of ongoing clinical trials. Overall, we identified six emerging strategies: targeting MAPK pathway (monotherapy or combinations), targeting MAPK pathway combined with cytotoxic agents, intensive cytotoxic regimen combinations, targeted agents combined with CPIs, oxidative stress induction, and cytotoxic agents combined with antiangiogenic drugs and CPIs. In the future, the integration of new therapeutic strategies targeting key players in the BRAFV600E oncogenic pathways with current treatment approach based on cytotoxic chemotherapy and surgery is likely to redefine the treatment landscape of these CRC patients.

Oxaliplatin retreatment in metastatic colorectal cancer: Systematic review and future research opportunities.

BACKGROUND: Oxaliplatin represents a main component of cytotoxic treatment regimens in colorectal cancer (CRC). Given its efficacy, oxaliplatin is frequently re-administered in the context of the continuum of care in metastatic CRC (mCRC). However, efficacy and tolerability of this therapeutic strategy has not been comprehensively assessed. METHODS: We performed a systematic review of the literature on September 19th 2020, according to PRISMA criteria 2009. The research was performed on PubMed, ASCO Meeting Library, ESMO library and ClinicalTrials.gov for citations or ongoing trials. RESULTS: 64 records were retrieved and 13 included in the systematic review: 8 full-text articles, 4 abstracts and 1 ongoing clinical trial. According to readministration timing, studies were classified as rechallenge/reintroduction (n = 8) or stop & go/intermittent therapeutic strategies (n = 4). The studies presented wide heterogeneity in terms of efficacy (Response Rate 6-31%; Disease Control Rate 39-79%; median Progression-Free Survival 3.1-7 months). Those patients who received retreatment after prior adjuvant oxaliplatin or exploiting a stop-&-go strategy appeared to achieve better outcomes. However, no formal comparisons on treatment outcomes were feasible. The most frequent grade 3 or higher adverse events were hematologic toxicities (5-27%), peripheral neuropathy (5-14%) and hypersensitivity reactions (5-20%). CONCLUSIONS: Retreatment with oxaliplatin for mCRC is practiced based on scarce and heterogeneous data indicating efficacy and manageable toxicity. The best strategy to exploit this approach remains to be defined, and the most promising research avenue to improve therapeutic index of oxaliplatin is represented by selection of responder patients whose tumors harbor molecular defects in the DNA damage repair pathway.

Long-term Clinical Outcome of Trastuzumab and Lapatinib for HER2-positive Metastatic Colorectal Cancer.

BACKGROUND: ERBB2 amplification occurs in 5% of RAS wild-type metastatic colorectal cancer (mCRC) and it has been shown to be a target for treatment with 2 HER2-directed combinations of trastuzumab and lapatinib or trastuzumab and pertuzumab. We present long-term clinical results of trastuzumab and lapatinib (HERACLES-A trial) at 6.7 years (82 months) follow-up and focus on central nervous system (CNS) recurrences. PATIENTS AND METHODS: Patients had histologically confirmed KRAS exon 2 (codons 12 and 13) wild-type and HER2-positive mCRC. HER2 positivity was assessed by immunohistochemistry and in situ hybridization HERACLES diagnostic criteria. Patients were treated with intravenous trastuzumab 4 mg/kg loading dose, then 2 mg/kg once per week, and oral lapatinib 1000 mg per day until disease progression or toxicity. Patients who presented with symptoms or signs of CNS disease received brain computed tomography scan or magnetic resonance imaging. RESULTS: A total of 35 patients received trastuzumab and lapatinib and 32 were evaluable for response. One patient (3%) achieved complete response (CR), 8 (25%) partial response, and 13 (41%) stable disease. Therefore, response rate was 28%. Median progression-free survival was 4.7 months (95% confidence interval [CI] 3.7-6.1). Median overall survival was 10.0 months (95% CI 7.9-15.8). One patient achieved sustained CR still maintained at 7 years of follow-up. Progression in the central nervous system (CNS) occurred in 6 (19%) of 32 patients. CONCLUSIONS: Long-term (6.7 years) follow-up analysis of HERACLES-A supports using of trastuzumab and lapatinib as treatment reference for KRAS wild-type, chemorefractory HER2-positive mCRC. In this subset of patients, prolongation of survival is accompanied by CNS recurrences that will require diagnostic and therapeutic attention in future studies. Clinicaltrials. Gov identifier: NCT 03225937.

High Circulating Methylated DNA Is a Negative Predictive and Prognostic Marker in Metastatic Colorectal Cancer Patients Treated With Regorafenib.

Background: Regorafenib improves progression free survival (PFS) in a subset of metastatic colorectal cancer (mCRC) patients, although no biomarkers of efficacy are available. Circulating methylated DNA (cmDNA) assessed by a five-gene panel was previously associated with outcome in chemotherapy treated mCRC patients. We hypothesized that cmDNA could be used to identify cases most likely to benefit from regorafenib (i.e., patients with PFS longer than 4 months). Methods: Plasma samples from mCRC patients were collected prior to (baseline samples N = 60) and/or during regorafenib treatment (N = 62) for the assessment of cmDNA and total amount of cell free DNA (cfDNA). Results: In almost all patients, treatment with regorafenib increased the total cfDNA, but decreased cmDNA warranting the normalization of cmDNA to the total amount of circulating DNA (i.e., cmDNA/ml). We report that cmDNA/ml dynamics reflects clinical response with an increase in cmDNA/ml associated with higher risk of progression (HR for progression = 1.78 [95%CI: 1.01-3.13], p = 0.028). Taken individually, high baseline cmDNA/ml (above median) was associated with worst prognosis (HR for death = 3.471 [95%CI: 1.83-6.57], p < 0.0001) and also predicted shorter PFS (<16 weeks with PPV 86%). In addition, high cmDNA/ml values during regorafenib treatment predicted with higher accuracy shorter PFS (<16 weeks with a PPV of 96%), therefore associated with increased risk of progression (HR for progression = 2.985; [95%CI: 1.63-5.46; p < 0.0001). Conclusions: Our data highlight the predictive and prognostic value of cmDNA/ml in mCRC patients treated with regorafenib.

Retreatment with anti-EGFR monoclonal antibodies in metastatic colorectal cancer: Systematic review of different strategies.

BACKGROUND: Despite advances in precision oncology and immunotherapy of tumors, little progress has been made in metastatic colorectal cancer (mCRC) in recent years. Therefore, making the most of available therapies is a necessity. Several studies, based on the pulsatile behavior of RAS clones under EGFR blockade, investigated whether readministration of EGFR-targeted agents is effective beyond second line. METHODS: A systematic review of studies of retreatment with anti-EGFR monoclonal antibodies has been performed from January 2005 to December 2018 according to PRISMA criteria from PubMed, ESMO and ASCO meetings libraries and Clinicaltrial.gov. Efficacy has been evaluated as objective response rate and survival in available publications. In addition, type and incidence of side effects occurring during on anti-EGFR retreatment have been considered. RESULTS: 26 publications have been retrieved, of which 20 full-text articles and 6 abstracts and categorized as for the retreatment strategy into five groups: rechallenge (n = 10), reintroduction (n = 4), sequence (n = 5), dose escalation (n = 1) and mixed (n = 6). Data of efficacy displayed high heterogeneity across different strategies (objective response rate, ORR = 0.0-53.8%; disease control rate, DCR = 24.0-89.7%), with best results in the setting of rechallenge (ORR = 2.9-53.8%; DCR = 40.0-89.7%). CONCLUSIONS: Rechallenge with anti-EGFR provides clinical benefit in molecularly selected mCRC patients beyond second line. Further ctDNA-guided studies comparing this option of treatment with current approved advanced line treatments are warranted.

Radiologic and Genomic Evolution of Individual Metastases during HER2 Blockade in Colorectal Cancer.

Targeting HER2 is effective in 24% of ERBB2 amplified metastatic colorectal cancer; however, secondary resistance occurs in most of the cases. We studied the evolution of individual metastases during treatment to discover spatially resolved determinants of resistance. Circulating tumor DNA (ctDNA) analysis identified alterations associated with resistance in the majority of refractory patients. ctDNA profiles and lesion-specific radiographic reports revealed organ- or metastasis-private evolutionary patterns. When radiologic assessments documented progressive disease in target lesions, response to HER2 blockade was retained in other metastases. Genomic and functional analyses on samples and cell models from eight metastases of a patient co-recruited to a postmortem study unveiled lesion-specific evolutionary trees and pharmacologic vulnerabilities. Lesion size and contribution of distinct metastases to plasma ctDNA were correlated.

TRKA expression and NTRK1 gene copy number across solid tumours.

AIMS: Neurotrophic Tropomyosin Kinase Receptor 1 (NTRK1) gene encodes for the protein Tropomyosin-related kinase A (TRKA). Deregulated activity of TRKA has been shown to have oncogenic potential. We present here the results of an immunohistochemical (IHC) observational cohort study of TRKA expression together with gene copy number (GCN) assessment in various solid tumours. METHODS: Formalin-fixed, paraffin-embedded consecutive samples of different tumour types were tested for TRKA expression. Samples showing TRKA IHC staining in at least 10% of cells were analysed by fluorescence in situ hybridisation to assess NTRK1 gene rearrangements and/or individual GCN gain. All patients underwent this molecular assessment within the phase I ALKA-001 clinical trial. RESULTS: 1043 samples were tested and annotation for histology was available in 1023. Most of the samples were colorectal adenocarcinoma (CRC) (n=550, 52.7%) and lung adenocarcinoma (n=312, 29.9%). 24 samples (2.3%) were biliary tract carcinoma (BTC). Overall, 17 (1.6%) samples were characterised by TRKA IHC expression (four weak, eight moderate, five strong): 9/17 lung adenocarcinoma, 3/17 CRC, 3/17 BTC, 1/17 thyroid cancer and 1/17 cancer of unknown primary. Of these, 1/17 with strong TRKA IHC staining displayed NTRK1 gene rearrangement and 15/17 NTRK1 GCN gain by FISH. No correlation was found between intensity of TRKA IHC staining and number of copies of NTRK1. CONCLUSIONS: TRKA expression can be found in 1.6% of solid tumours and can be paralleled by NTRK1 gene rearrangements or mostly GCN gain. The prognostic and translational therapeutic impact of the latter remains to be established.

Pooled Analysis of Clinical Outcome of Patients with Chemorefractory Metastatic Colorectal Cancer Treated within Phase I/II Clinical Studies Based on Individual Biomarkers of Susceptibility: A Single-Institution Experience.

BACKGROUND: Patients with metastatic colorectal cancer (mCRC) refractory to standard therapies have a poor prognosis. In this setting, recruitment into clinical trials is warranted, and studies driven by selection according to individual tumor molecular characteristics are expected to provide added value. OBJECTIVE: We retrospectively analyzed data from patients with mCRC refractory to or following failure of standard therapies who were enrolled into phase I/II clinical studies at the Niguarda Cancer Center based on the presence of a specific molecular profile expected to represent the target of susceptibility to the experimental drug(s). PATIENTS AND METHODS: From June 2011 to May 2016, 2044 patients with mCRC underwent molecular screening. Eighty patients (3.9%) were enrolled in ad hoc studies; the median age was 60 years (range 36-86) and the median number of previous treatment lines was five (range 2-8). Molecular characteristics exploited within these studies were MGMT promoter hypermethylation (48.7%), HER2 amplification (28.8%), BRAF V600E mutation (20%), and novel gene fusions involving ALK or NTRK (2.5%). RESULTS: One patient (1%) had RECIST (Response Evaluation Criteria In Solid Tumors) complete response (CR), 13 patients (16.5%) experienced a partial response (PR), and 28 (35%) stable disease (SD). Median progression-free survival (PFS) was 2.8 months (range 2.63-3.83), with 24% of patients displaying PFS >5 months. Median growth modulation index (GMI) was 0.85 (range 0-15.61) and 32.5% of patients had GMI >1.33. KRAS exon 2 mutations were found in 38.5% of patients, and among the 78 patients with known KRAS status, those with wild-type tumors had longer PFS than those with mutated tumors (3.80 [95% CI 2.80-5.03] vs. 2.13 months [95% CI 1.77-2.87], respectively, p = 0.001). Median overall survival (OS) was 7.83 months (range 7.17-9.33) for all patients, and patients with KRAS wild-type tumors had longer OS than those with mutated tumors (7.83 [95% CI 7.33-10.80] vs. 7.18 months [95% CI 5.63-9.33], respectively, p = 0.06). CONCLUSIONS: This single-institution retrospective study indicates that in a heavily pretreated population approximately 4% of mCRC tumors display a potential actionable molecular context suitable for therapeutic intervention. Application of molecular selection is challenging but improves clinical outcome even in later lines of treatment.

Oxaliplatin Immune-Induced Syndrome Occurs With Cumulative Administration and Rechallenge: Single Institution Series and Systematic Review Study.

Oxaliplatin immune-induced syndrome (OIIS) is an uncommon, potentially life-threatening, side effect associated with oxaliplatin-based chemotherapy. The present study reports 5 original cases of OIIS and systematically reviewed the available published cases. We retrospectively analyzed the clinical archives of the Niguarda Cancer Center from 2009 to 2015 and conducted a search for OIIS using the PubMed database, followed by deeper investigation of the references of the recorded studies. We pooled our series with other reported cases for systematic review in accordance with the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement using only English language as the selection criterion. A total of 61 OIIS cases were analyzed, the largest series reported to date. Of the 61 patients, 56 (91.8%) had received oxaliplatin for metastatic colorectal cancer. In 32 of the 61 patients (52.5%), OIIS was associated with grade 4 thrombocytopenia and in 4 (6.6%) with grade 4 anemia. OIIS was fatal in 4 patients. In 49 patients, oxaliplatin-induced immune system activation was tested using the Coombs test or by detection of antiplatelet antibodies and was positive in 87.7% of the patients. The average number of oxaliplatin cycles until the onset of OIIS was 16.7, and the number was significantly lower when oxaliplatin was administered as a rechallenge after a period of vacancy of treatment with this agent (4.6 cycles as rechallenge vs. 13.6 as first-time exposure; P < .00001). OIIS is triggered by cumulative administration of oxaliplatin, characteristically with a threefold earlier onset when the drug is administered as a rechallenge. Prompt identification of OIIS can be expected to reduce the risk of iatrogenic morbidity and mortality.

Sensitivity to Entrectinib Associated With a Novel LMNA-NTRK1 Gene Fusion in Metastatic Colorectal Cancer.

In metastatic colorectal cancer (CRC), actionable genetic lesions represent potential clinical opportunities. NTRK1, 2, and 3 gene rearrangements encode oncogenic fusions of the tropomyosin-receptor kinase (TRK) family of receptor tyrosine kinases in different tumor types. The TPM3-NTRK1 rearrangement is a recurring event in CRC that renders tumors sensitive to TRKA kinase inhibitors in preclinical models. We identified abnormal expression of the TRKA protein in tumor and liver metastases of a CRC patient refractory to standard therapy. Molecular characterization unveiled a novel LMNA-NTRK1 rearrangement within chromosome 1 with oncogenic potential, and the patient was treated with the pan-TRK inhibitor entrectinib, achieving partial response with decrease in hepatic target lesions from 6.8 and 8.2cm in longest diameter to 4.7 and 4.3cm, respectively. To our knowledge, this is the first clinical evidence of efficacy for therapeutic inhibition of TRKA in a solid tumor, illuminating a genomic-driven strategy to identify CRCs reliant on this oncogene to be clinically targeted with entrectinib.