IMPACT OF KRAS/NRAS MUTATIONAL HETEROGENEITY ON CLINICAL OUTCOMES IN COLORECTAL CANCER

Introduction: Mutations in KRAS/NRAS (RAS) predict a lack of benefit from anti-EGFR agents in metastatic colorectal cancer (mCRC). As next generation sequencing (NGS) has advanced, we are discovering atypical and low allele frequency mutations. We aimed to evaluate how NGS can optimally define RAS mutant CRC and the role of relative mutant allele frequency (rMAF) as a biomarker. Methods: Using institutional and public cohorts of mCRC patients with NGS results, we described the prevalence and clinical impact of atypical (not in current guidelines) and low rMAF RAS mutations (RAS MAF by the MAF of the mutated gene with the highest allele frequency to normalize for tumor content. Functional annotation of 113 RAS mutations was performed and functionality of mutations was compared to rMAF. Results: RAS mutations were noted in 4244/8609 patients (49.3%), with atypical mutations in 1.3% of patients. The most prevalent atypical mutations were KRAS Q22K (0.2%), KRAS D33E (0.1%) and KRAS T50I (0.1%). Of 113 functionally characterized RAS mutations, all 23 non-activating mutations were atypical, while every guideline cited mutation was activating. Atypical variants (HR 2.45, P=0.0092) and those that resulted in MAPK activity greater than KRAS exon 2 (HR 1.40, P=0.028) had a worse OS. A RAS rMAF \u3e50% was associated with worse OS than rMAFRAS mutation was associated with a worse OS than wild-type patients. The rMAF of any mutated gene was also associated with functional significance in a clinically annotated database, yet the magnitude of difference in rMAF was not sufficient to warrant clinical utility in tissue cohorts. However, a cfDNA cohort did show striking results demonstrating rMAF was associated with a variants functional characterization. Conclusions: Through a comprehensive atlas of RAS functional characterization, we show that several atypical variants appear clinically relevant. Although rMAF was not useful in characterizing variants as damaging, our findings that RAS rMAF is associated with prognosis suggests allele frequency may be useful information in standard clinical reports

NRG GI008: Colon adjuvant chemotherapy based on evaluation of residual disease (CIRCULATE-US)

Background: Currently, there are no biomarkers validated prospectively in randomized studies for resected colon cancer (CC) to determine need for adjuvant chemotherapy (AC). However, circulating tumor DNA (ctDNA) represents a highly specific and sensitive approach (especially with serial monitoring) for identifying minimal/molecular residual disease (MRD) post-surgery in CC patients (pts), and may outperform traditional clinical and pathological features in prognosticating risk for recurrence. CC pts who do not have detectable ctDNA (ctDNA-) are at a much lower risk of recurrence and may be spared the toxicities associated with AC. Furthermore, for CC pts with detectable ctDNA (ctDNA+) who are at a very high risk of recurrence, the optimal AC regimen has not been established. We hypothesize that for pts whose CC has been resected, ctDNA status may be used to risk-stratify for making decisions about AC. Methods: In this prospective phase II/III trial, up to 1,912 pts with resected stage III A, B (all pts) and stage II, IIIC (ctDNA+ only) CC will be enrolled. Based on the post-operative ctDNA status using personalized and tumor-informed assay (Signatera™, bespoke assay), those who are ctDNA- (Cohort A) will be randomized to immediate AC with fluoropyrimidine (FP) + oxaliplatin (Ox) for 3-6 mos per established guidelines vs. serial ctDNA monitoring. Patients who are ctDNA+ post-operatively or with serial monitoring (Cohort B) will be randomized to FP+Ox vs. more intensive AC with addition of irinotecan (I) for 6 mos. The primary endpoints for Cohort A are time to ctDNA+ status (phase II) and disease-free survival (DFS) (phase III) in the immediate vs. delayed AC arms. The primary endpoint for Cohort B is DFS in the FP+Ox vs FP+Ox+I arms for both phase II and phase III portions of the trial. Secondary endpoints include prevalence of detectable ctDNA post-operatively, time-to-event outcomes (overall survival and time to recurrence) by ctDNA status, and the assessment of compliance to adjuvant therapy. Biospecimens including archival tumor tissue, as well as post-operative plus serial matched/normal blood samples, will be collected for exploratory correlative research. Active enrollment across the NCTN started in June, 2022. Support: U10-CA-180868, -180822; UG1CA-189867; Natera, Inc. Clinical trial information: NCT05174169

A tailored approach to horizon scanning for cancer medicines

BACKGROUND: Horizon scanning (HS) is the systematic identification of emerging therapies to inform policy and decision-makers. We developed an agile and tailored HS methodology that combined multi-criteria decision analysis weighting and Delphi rounds. As secondary objectives, we aimed to identify new medicines in melanoma, non-small cell lung cancer and colorectal cancer most likely to impact the Australian government's pharmaceutical budget by 2025 and to compare clinician and consumer priorities in cancer medicine reimbursement.METHOD: Three cancer-specific clinician panels (total n = 27) and a consumer panel (n = 7) were formed. Six prioritisation criteria were developed with consumer input. Criteria weightings were elicited using the Analytic Hierarchy Process (AHP). Candidate medicines were identified and filtered from a primary database and validated against secondary and tertiary sources. Clinician panels participated in a three-round Delphi survey to identify and score the top five medicines in each cancer type.RESULTS: The AHP and Delphi process was completed in eight weeks. Prioritisation criteria focused on toxicity, quality of life (QoL), cost savings, strength of evidence, survival, and unmet need. In both curative and non-curative settings, consumers prioritised toxicity and QoL over survival gains, whereas clinicians prioritised survival. HS results project the ongoing prevalence of high-cost medicines. Since completion in October 2021, the HS has identified 70 % of relevant medicines submitted for Pharmaceutical Benefit Advisory Committee assessment and 60% of the medicines that received a positive recommendation.CONCLUSION: Tested in the Australian context, our method appears to be an efficient and flexible approach to HS that can be tailored to address specific disease types by using elicited weights to prioritise according to incremental value from both a consumer and clinical perspective.POLICY SUMMARY: Since HS is of global interest, our example provides a reproducible blueprint for adaptation to other healthcare settings that integrates consumer input and priorities.</p

Recent developments in the treatment of metastatic colorectal cancer

Over the past decade there have been significant advances in the molecular characterization of colorectal cancer (CRC) that are driving treatment decisions. Expanded RAS testing beyond KRAS exon 2 was established as crucial for identifying patients who will respond to anti-epidermal growth factor receptor (EGFR) therapies and low-frequency mutations in RAS /tumor heterogeneity are gaining recognition as potential mechanisms of resistance. Despite this progress, the fact that we do not understand why left-sided but not right-sided tumors have improved outcomes following anti-EGFR therapy highlights our superficial understanding of this disease. Even with few new targeted agents receiving approval in CRC, the incorporation of next-generation sequencing into clinical decision making represents an important step forward. Biomarkers such as BRAF mutations, microsatellite instability, and HER2 amplification represent promising molecular aberrations with therapies in various stages of development, and highlight the importance of companion diagnostics in supporting targeted agents. In this review, we will discuss the importance of incorporating biomarkers into clinical decision making and regimen selection in CRC. We will particularly focus on the recent evidence suggesting an important role for tumor location in selecting first-line therapy, the importance of recent advances in biomarker development and molecular subtyping, as well as recently approved agents (regorafenib and TAS-102) and promising targeted agents that have the potential to change the standard of care

Case Report of Cirrhosis following Yttrium-90 Radioembolization for Pancreatic Neuroendocrine Liver Metastases

Background: Management options for pancreatic neuroendocrine tumors (pNETs) metastatic to the liver include surgical, ablative, cytotoxic, and radioisotope approaches. One potential local treatment option includes selective internal radiotherapy utilizing yttrium-90 (90Y) microspheres. 90Y has also been used in the treatment of hepatocellular carcinoma and tumors metastatic to the liver. It appears to be well tolerated; however, there is no randomized controlled trial reporting long-term toxicities. Previous retrospective reports have described biliary damage as a potential complication of therapy with 90Y and chemoembolization; however, the long-term sequelae of 90Y treatment are poorly understood. Case Presentation: We present the case of a 65-year-old Caucasian woman who suffered biliary damage following 90Y administration for metastatic pNETs and subsequently developed cirrhosis. Given the timeline of her various treatments and the lack of any other identifiable etiology for her cirrhosis, we believe this to be a potential long-term complication of 90Y therapy. Conclusion: This case provides pathologic confirmation of cirrhosis as a potential long-term sequela of 90Y treatment. This long-term risk needs to be considered when sequencing therapy for patients with neuroendocrine tumors who have a good prognosis. There are now several other systemic and ablative treatment options available to these patients, and long-term complications must be considered during treatment

Feasibility of circulating tumor DNA (ctDNA) to guide organ preservation in patients with node-negative rectal cancer undergoing neoadjuvant chemotherapy, excision, and observation in the phase II CCTG CO.28 trial

Background:CCTG CO.28 evaluated 3 months of neoadjuvant CAPOX or FOLFOX followed by transanal excision surgery (TES) in patients (pts) with T1-T3, N0 rectal cancers with the goal of organ preservation. Total mesorectal excision (TME) was recommended for inadequate downstaging or high-risk features on TES pathology. Detection of ctDNA is associated with a high rate of recurrence in high risk resected colorectal cancer. However, the sensitivity of ctDNA in early-stage rectal cancer is unclear.Methods:Tissue CGP was performed retrospectively on pretreatment resected tumor using Foundation OneCDx (F1CDx), followed by MRD detection using FoundationOneTracker. Briefly, variants were selected from F1CDx using an algorithm that filters out non-tumor derived variants (e.g. germline). A tumor-informed personalized multiplex PCR-next generation sequencing assay, consisting of up to 16 variants, was used to detect ctDNA and quantify plasma mean variant allelic frequency (VAF) and mean tumor molecules per mL of plasma (MTM/mL). FoundationOneTracker was performed on blood samples collected pre/post-neoadjuvant chemotherapy. Buffy coat sequencing was performed at FMI to validate the monitoring variant selection algorithm.Results:52 pts underwent F1CDx and FoundationOneTracker analysis. KRAS mutations were observed in 60% (n =31) of cases; MSI-H and BRAF V600E mutations were not detected. From 1,580 distinct variants detected in tissue and paired buffy coat sequencing, 985 had VAF \u3e30% in the buffy coat specimen and were considered germline. The variant selection algorithm filtered 99.8% (n = 983) of germline variants; the remaining 2 were not selected for primer design. A median of 7 variants (range 2-16) were tracked per pt. Detectable ctDNA was found in 0% (0/6), 19% (6/32) and 55% (6/11) of treatment naïve T1, T2 and T3ab cases, respectively, and 83% of those which were initially positive (10/12) cleared ctDNA post chemotherapy. Three pts had detectable ctDNA pre-excision, including 1 who was negative pretreatment. From 42 pts with pre/post-treatment plasma, 19 pts were recommended for TME; 2 had detectable ctDNA, 5 had ctDNA clearance, and 12 had no ctDNA detection.Conclusions:Node-negative rectal cancer exhibited ctDNA shed in a minority of pts, with most clearing ctDNA on chemotherapy before their TES. The dynamic ctDNA signal we demonstrate could supplement clinical factors in informing organ preservation in very early-stage rectal cancer. Larger studies are needed to determine if this information can be used to personalize therapy. Clinical trial information: NCT03259035

Colorectal Cancer and Onset of Anxiety and Depression : A Systematic Review and Meta-Analysis

Research suggests that colorectal cancer (CRC) is associated with mental health disorders, primarily anxiety and depression. To synthesize this evidence, we conducted a systematic review and meta-analysis of studies evaluating the onset of anxiety and depression among patients with CRC. We searched EMBASE and Medline from inception to June 2022. We included original, peer-reviewed studies that: used an epidemiologic design; included patients with CRC and a comparator group of individuals without cancer; and evaluated anxiety and depression as outcomes. We used random effects models to obtain pooled measures of associations. Quality assessment was completed using the Newcastle-Ottawa scale. Of 7326 articles identified, 8 were eligible; of which 6 assessed anxiety and depression and 2 assessed depression only. Meta-analyses showed a non-significant association between CRC and anxiety (pooled HR 1.67; 95% CI 0.88 to 3.17) and a significant association between CRC and depression (pooled HR 1.78; 95% CI 1.23 to 2.57). Predictors of anxiety and depression among patients with CRC included clinical characteristics (e.g., comorbidities, cancer stage, cancer site), cancer treatment (e.g., radiotherapy, chemotherapy, colostomy), and sociodemographic characteristics (e.g., age, sex). The impacts of anxiety and depression in patients with CRC included increased mortality and decreased quality of life. Altogether, our systematic review and meta-analysis quantified the risks and impacts of CRC on anxiety and depression, particularly an increased risk of depression after CRC diagnosis. Findings provide support for oncologic care that encompasses mental health supports for patients with CRC.Medicine, Faculty ofPharmaceutical Sciences, Faculty ofOther UBCNon UBCMedicine, Department ofPopulation and Public Health (SPPH), School ofReviewedFacultyResearcherGraduat