Tumour mutational burden as a biomarker in patients with mismatch repair deficient/microsatellite instability-high metastatic colorectal cancer treated with immune checkpoint inhibitors

BACKGROUND

Immune checkpoint inhibitors (ICIs) are the standard treatment in patients with mismatch repair deficient (dMMR)/microsatellite instability-high (MSI-H) metastatic colorectal cancer (mCRC). Tumour mutational burden (TMB) is a promising biomarker for the prediction of treatment outcomes.

PATIENTS AND METHODS

We screened 203 patients with dMMR/MSI-H mCRC treated with an anti-PD-(L)1 (anti-Programmed-Death-(Ligand)1) plus or minus an anti-Cytotoxic T-Lymphocyte Antigen 4 (anti-CTLA-4) agent at three Italian Academic Centers. TMB was tested by Foundation One Next Generation Sequencing assay and correlated with clinical outcomes, in the overall population and according to ICI regimen.

RESULTS

We included 110 patients with dMMR/MSI-H mCRC. Eighty patients received anti-PD-(L)1 monotherapy and 30 received anti-CTLA-4 combinations. Median TMB was 49 mut/Mb (range: 8-251 mut/Mb). The optimal prognostic cut-off for progression-free survival (PFS) stratification was 23 mut/Mb. Patients with TMB ≤23 mut/Mb had significantly worse PFS (adjusted Hazard Ratio [aHR] = 4.26, 95% confidence interval [CI]:1.85-9.82, p = 0.001) and overall survival (OS) (aHR = 5.14, 95% CI: 1.76-14.98, p = 0.003). Using a cut-off optimised for predicting treatment outcome, anti-CTLA-4 combination was associated with a significant PFS/OS benefit versus anti-PD-(L)1 monotherapy in patients with TMB>40 mut/Mb (2-year PFS: 100.0% versus 70.7%, p = 0.002; 2-year OS: 100.0% versus 76.0%, p = 0.025), but not in those with TMB ≤40 mut/Mb (2-year PFS: 59.7% versus 68.6%, p = 0.888; 2-year OS: 80.0% versus 81.0%, p = 0.949).

CONCLUSION

Patients with dMMR/MSI-H mCRC and relatively lower TMB value displayed early disease progression when receiving ICIs, whereas patients with the highest TMB values may obtain the maximal benefit from intensified anti-CTLA-4/PD-1 combination.

Fruquintinib versus placebo in patients with refractory metastatic colorectal cancer (FRESCO-2): an international, multicentre, randomised, double-blind, phase 3 study

BACKGROUND

There is a paucity of effective systemic therapy options for patients with advanced, chemotherapy-refractory colorectal cancer. We aimed to evaluate the efficacy and safety of fruquintinib, a highly selective and potent oral inhibitor of vascular endothelial growth factor receptors (VEGFRs) 1, 2, and 3, in patients with heavily pretreated metastatic colorectal cancer.

METHODS

We conducted an international, randomised, double-blind, placebo-controlled, phase 3 study (FRESCO-2) at 124 hospitals and cancer centres across 14 countries. We included patients aged 18 years or older (≥20 years in Japan) with histologically or cytologically documented metastatic colorectal adenocarcinoma who had received all current standard approved cytotoxic and targeted therapies and progressed on or were intolerant to trifluridine-tipiracil or regorafenib, or both. Eligible patients were randomly assigned (2:1) to receive fruquintinib (5 mg capsule) or matched placebo orally once daily on days 1-21 in 28-day cycles, plus best supportive care. Stratification factors were previous trifluridine-tipiracil or regorafenib, or both, RAS mutation status, and duration of metastatic disease. Patients, investigators, study site personnel, and sponsors, except for selected sponsor pharmacovigilance personnel, were masked to study group assignments. The primary endpoint was overall survival, defined as the time from randomisation to death from any cause. A non-binding futility analysis was done when approximately one-third of the expected overall survival events had occurred. Final analysis occurred after 480 overall survival events. This study is registered with ClinicalTrials.gov, NCT04322539, and EudraCT, 2020-000158-88, and is ongoing but not recruiting.

FINDINGS

Between Aug 12, 2020, and Dec 2, 2021, 934 patients were assessed for eligibility and 691 were enrolled and randomly assigned to receive fruquintinib (n=461) or placebo (n=230). Patients had received a median of 4 lines (IQR 3-6) of previous systemic therapy for metastatic disease, and 502 (73%) of 691 patients had received more than 3 lines. Median overall survival was 7·4 months (95% CI 6·7-8·2) in the fruquintinib group versus 4·8 months (4·0-5·8) in the placebo group (hazard ratio 0·66, 95% CI 0·55-0·80; p<0·0001). Grade 3 or worse adverse events occurred in 286 (63%) of 456 patients who received fruquintinib and 116 (50%) of 230 who received placebo; the most common grade 3 or worse adverse events in the fruquintinib group included hypertension (n=62 [14%]), asthenia (n=35 [8%]), and hand-foot syndrome (n=29 [6%]). There was one treatment-related death in each group (intestinal perforation in the fruquintinib group and cardiac arrest in the placebo group).

INTERPRETATION

Fruquintinib treatment resulted in a significant and clinically meaningful benefit in overall survival compared with placebo in patients with refractory metastatic colorectal cancer. These data support the use of fruquintinib as a global treatment option for patients with refractory metastatic colorectal cancer. Ongoing analysis of the quality of life data will further establish the clinical benefit of fruquintinib in this patient population.

FUNDING

HUTCHMED.

The ideal reporting of RAS testing in colorectal adenocarcinoma: a pathologists' perspective

RAS gene mutational status represents an imperative predictive biomarker to be tested in the clinical management of metastatic colorectal adenocarcinoma. Even if it is one of the most studied biomarkers in the era of precision medicine, several pre-analytical and analytical factors may still impasse an adequate reporting of RAS status in clinical practice, with significant therapeutic consequences. Thus, pathologists should be aware on the main topics related to this molecular evaluation: (i) adopt diagnostic limit of detections adequate to avoid the interference of sub-clonal cancer cell populations; (ii) choose the most adequate diagnostic strategy according to the available sample and its qualification for molecular testing; (iii) provide all the information regarding the mutation detected, since many RAS mutation-specific targeted therapeutic approaches are in development and will enter into routine clinical practice. In this review, we give a comprehensive description of the current scenario about RAS gene mutational testing in the clinic focusing on the pathologist's role in patient selection for targeted therapies.

Role of Immune Microenvironment in Pancreatic Ductal Adenocarcinoma: Could It Be Considered a Predictor of Prognosis?

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a highly immunosuppressive tumor microenvironment (TME). The aim of this study is to determine the potential significant TME immune markers of long-term survival.

METHODS

We retrospectively included patients with a diagnosis of resectable PDAC having undergone upfront surgery. Immunohistochemical (IHC) staining using tissue microarray for PD-L1, CD3, CD4, CD8, FOXP3, CD20, iNOS and CD163 was performed in order to characterize the TME. The primary endpoint was long-term survival, defined as the Overall Survival > 24 months from surgery.

RESULTS

A total of 38 consecutive patients were included, and 14 (36%) of them were long-term survivors. Long-term survivors showed a higher density of CD8+ lymphocytes intra- and peri-acinar (p = 0.08), and a higher CD8/FOXP3 intra- and peri-tumoral ratio (p = 0.05). A low density of intra- and peri-tumoral FOXP3 infiltration is a good predictor of long-term survival (p = 0.04). A significant association of the low density of intra- and peri-tumoral tumor-associated macrophages (TAMs) iNOS+ with long-term survival was detected (p = 0.04).

CONCLUSIONS

Despite the retrospective nature and small sample size, our study showed that the high infiltration of CD8+ lymphocytes and low infiltration of FOXP3+ and TAMs iNOS+ are predictors of good prognosis. A preoperative assessment of these potential immune markers could be useful and determinant in the staging process and in PDAC management.

The role of nanoliposomal irinotecan plus fluorouracil/leucovorin in the continuum of care of patients with metastatic pancreatic ductal adenocarcinoma

BACKGROUND

The NAPOLI-I trial showed better outcome of nanoliposomal irinotecan (nal-IRI) plus 5-fluorouracil/leucovorin (5-FU/LV) compared to 5-FU/LV in patients with advanced pancreatic ductal adenocarcinoma cancer (advPDAC) progressed to gemcitabine-based therapy. This study aims to explore the real-world efficacy and safety of 5-FU/LV-nal-IRI.

METHODS

This is a retrospective multicenter analysis including advPDAC patients receiving 5-FU/LV-nal-IRI after failure of gemcitabine-based therapy. Survival analyses were performed using Kaplan-Meier method, univariate and multivariate analyses by Cox regression.

RESULTS

A total of 296 patients (median age 64.4 years, ECOG PS ≥1 in 56% of cases) were treated at 11 Italian institutions between 2016 and 2018. 34% of them underwent primary tumor resection, and 79% received gemcitabine-nabpaclitaxel as first line. 5-FU/LV-nal-IRI was administered as second-line in 73% of cases. Objective response and disease control rate were 12% and 41%, respectively. Treatment was well tolerated with dose reductions in 50% of patients but no one permanent discontinuation; the commonest grade ≥3 toxicities were neutropenia (14%) and diarrhea (12%). Median PFS and OS from 5-FU/LV-nal-IRI initiation was 3.2 and 7.1 months, respectively.

CONCLUSIONS

These real-world data confirm the 5-FU/LV-nal-IRI efficacy and safety in advPDAC patients progressed to gemcitabine-based therapy, with outcomes comparable to NAPOLI-1, even in a less-selected population and with more modern therapeutic algorithm.

Outcomes and a prognostic classifier in patients with microsatellite instability-high metastatic gastric cancer receiving PD-1 blockade

BACKGROUND

Subgroup analyses of randomized trials suggest the superiority of immune checkpoint inhibitor-based therapy over chemotherapy in patients with mismatch-repair deficient (dMMR) and/or microsatellite instability-high (MSI-high) advanced gastric or gastroesophageal junction adenocarcinoma. However, these subgroups are small and studies examining prognostic features within dMMR/MSI-high patients are lacking.

METHODS

We conducted an international cohort study at tertiary cancer centers and collected baseline clinicopathologic features of patients with dMMR/MSI-high metastatic or unresectable gastric cancer treated with anti-programmed cell death protein-1 (PD-1)-based therapies. The adjusted HRs of variables significantly associated with overall survival (OS) were used to develop a prognostic score.

RESULTS

One hundred and thirty patients were included. At a median follow-up of 25.1 months, the median progression-free survival (PFS) was 30.3 months (95% CI: 20.4 to NA) and 2-year PFS rate was 56% (95% CI: 48% to 66%). Median OS was of 62.5 months (95% CI: 28.4 to NA) and 2-year OS rate was 63% (95% CI: 55% to 73%). Among the 103 Response Evaluation Criteria in Solid Tumors-evaluable patients, objective response rate was 66% and disease control rate 87% across lines of therapy. In the multivariable models, Eastern Cooperative Oncology Group Performance Status of 1 or 2, non-resected primary tumor, presence of bone metastases and malignant ascites were independently associated with poorer PFS and OS. These four clinical variables were used to build a three-category (ie, good, intermediate, and poor risk) prognostic score. Compared with patients with good risk, patients with intermediate risk score had numerically inferior PFS and OS (2-year PFS rate: 54.3% versus 74.5%, HR 1.90, 95% CI: 0.99 to 3.66; 2-year OS rate: 66.8% versus 81.2%, HR 1.86, 95% CI: 0.87 to 3.98), whereas patients with poor risk score had significantly inferior PFS and OS (2-year PFS rate: 10.6%, HR 9.65, 95% CI: 4.67 to 19.92; 2-year OS rate: 13.3%, HR 11.93, 95% CI: 5.42 to 26.23).

CONCLUSIONS

Overall outcomes with anti-PD-1-based therapies are favorable in MSI-high gastroesophageal adenocarcinomas. However, within this overall favorable subgroup a more accurate prognostication using baseline clinical characteristics might identify patients at higher risk of rapid disease progression who may deserve intensified immunotherapy combination strategies.

Dissecting tumor lymphocyte infiltration to predict benefit from immune-checkpoint inhibitors in metastatic colorectal cancer: lessons from the AtezoT RIBE study

BACKGROUND

Tumor immune cells influence the efficacy of immune-checkpoint inhibitors (ICIs) and many efforts aim at identifying features of tumor immune microenvironment able to predict benefit from ICIs in proficient mismatch repair (pMMR)/microsatellite stable (MSS) metastatic colorectal cancer (mCRC).

METHODS

We characterized tumor immune cell infiltrate, by assessing tumor-infiltrating lymphocytes (TILs), Immunoscore, Immunoscore-IC, and programmed death ligand-1 (PD-L1) expression in tumor samples of patients with mCRC enrolled in the AtezoTRIBE study, a phase II randomized trial comparing FOLFOXIRI/bevacizumab/atezolizumab to FOLFOXIRI/bevacizumab, with the aim of evaluating the prognostic and predictive value of these features.

RESULTS

Out of 218 patients enrolled, 181 (83%), 77 (35%), 157 (72%) and 162 (74%) specimens were successfully tested for TILs, Immunoscore, Immunoscore-IC and PD-L1 expression, respectively, and 69 (38%), 45 (58%), 50 (32%) and 21 (13%) tumors were classified as TILs-high, Immunoscore-high, Immunoscore-IC-high and PD-L1-high, respectively. A poor agreement was observed between TILs and Immunoscore or Immunoscore-IC (K of Cohen <0.20). In the pMMR population, longer progression-free survival (PFS) was reported for Immunoscore-high and Immunoscore-IC-high groups compared with Immunoscore-low (16.4 vs 12.2 months; HR: 0.55, 95% CI: 0.30 to 0.99; p=0.049) and Immunoscore-IC-low (14.8 vs 11.5 months; HR: 0.55, 95% CI: 0.35 to 0.85; p=0.007), respectively, with a significant interaction effect between treatment arms and Immunoscore-IC (p for interaction: 0.006) and a trend for Immunoscore (p for interaction: 0.13). No PFS difference was shown according to TILs and PD-L1 expression. Consistent results were reported in the overall population.

CONCLUSIONS

The digital evaluation of tumor immune cell infiltrate by means of Immunoscore-IC or Immunoscore identifies the subset of patients with pMMR mCRC achieving more benefit from the addition of the anti-PD-L1 to the upfront treatment. Immunoscore-IC stands as the most promising predictor of benefit from ICIs.

Identification of Atezolizumab Plus Bevacizumab Prognostic Index via Recursive Partitioning Analysis in HCC: The ABE Index

BACKGROUND/AIM

The purpose of this study was to ascertain a novel prognostic index via recursive partitioning analysis (RPA) in hepatocellular carcinoma (HCC) patients being treated with the combination of atezolizumab plus bevacizumab (ABE) in first-line setting.

PATIENTS AND METHODS

A total of 784 patients with HCC were included in the analysis.

RESULTS

RPA identified three groups of patients: high-risk [Child-Pugh B (CP-B) patients; CP-A and Albumin-Bilirubin (ALBI)-2 patients; CP-A and ALBI-1 patients with macrovascular invasion (MVI), and alpha-fetoprotein (α-FP) ≥400 ng/ml]; intermediate-risk [CP-A and ALBI-1 patients with aspartate aminotransferase (AST) normal value (NV), and αFP ≥400 ng/ml, but without MVI; CP-A and ALBI-1 patients with AST increased value (IV), and neutrophil-lymphocyte ratio (NLR) ≥3, but without MVI]; low-risk (CP-A and ALBI-1 patients with AST NV, and αFP <400 ng/ml, but without MVI; CP-A and ALBI-1 patients with AST IV, and NLR <3, but without MVI; CP-A and ALBI-1 patients with MVI, and αFP <400 ng/ml). Overall survival was 7.0 months in high-risk patients (20.8%), 14.2 months in intermediate-risk patients (19.1%), and 22.5 months in low-risk patients (60.1%).

CONCLUSION

The ABE index allows for easy stratification of HCC patients treated with the combination of ABE in first-line setting.

Real-World Data for Atezolizumab Plus Bevacizumab in Unresectable Hepatocellular Carcinoma: How Does Adherence to the IMbrave150 Trial Inclusion Criteria Impact Prognosis?

BACKGROUND

Atezolizumab plus bevacizumab has recently been approved as a new first-line standard of care for patients with unresectable hepatocellular carcinoma (HCC).

OBJECTIVE

We performed a real-world study to evaluate the impact of the IMbrave150 trial inclusion criteria on the safety and efficacy of treatment outside of clinical trials.

METHODS

We analyzed patients treated with atezolizumab plus bevacizumab for unresectable HCC from four different countries. No specific inclusion and exclusion criteria were applied, except for the absence of previous systemic therapies for HCC. The entire population was split into two groups according to concordance with the inclusion criteria as reported in the IMbrave150 trial in 'IMbrave150-in' and 'IMbrave150-out' patients, and safety and efficacy in the two groups of patients were evaluated.

RESULTS

Overall, 766 patients were included in the analysis: 561/766 (73%) in the 'IMbrave150-in' group and 205/766 (27%) in the 'IMbrave150-out' group. Median overall survival (OS) and median progression-free survival (PFS) were 16.3 versus 14.3 months (hazard ratio [HR] 0.48, 95% confidence interval [CI] 0.35-0.65; p < 0.0001] and 8.3 versus 6.0 months (HR 0.79, 95% CI 0.63-0.99; p = 0.0431) in 'IMbrave150-in' and 'IMbrave150-out' patients, respectively. Multivariate analysis confirmed that patients included in the 'IMbrave150-in' group had significantly longer OS compared with patients included in the 'IMbrave150-out' group (HR 0.76, 95% CI 0.47-0.97; p = 0.0195). In 'IMbrave150-in' patients, the albumin-bilirubin (ALBI) grade was not associated with OS, whereas in 'IMbrave150-out' patients, those with ALBI grade 1 reported a significant benefit in terms of OS compared with those with ALBI grade 2 (16.7 vs. 5.9 months; HR 4.40, 95% CI 2.40-8.08; p > 0.0001). No statistically significant differences were reported in the 'IMbrave150-in' and 'IMbrave150-out' groups in terms of safety profile.

CONCLUSION

Adherence to the IMbrave150 trial inclusion criteria favorably impacts the prognosis of patients receiving atezolizumab plus bevacizumab. Among patients who did not meet the IMbrave150 inclusion criteria, those with ALBI grade 1 could benefit from the treatment.

Cetuximab as third-line rechallenge plus either irinotecan or avelumab is an effective treatment in metastatic colorectal cancer patients with baseline plasma RAS/BRAF wild-type circulating tumor DNA: Individual patient data pooled analysis of CRICKET and CAVE trials

The rechallenge strategy is based on the concept that a subset of patients with RAS wild-type (WT) metastatic colorectal cancer (mCRC) could still benefit of epidermal growth factor receptor (EGFR) inhibition, after progression to an anti-EGFR based-therapy. We performed a pooled analysis of two-phase II prospective trials to determine the role of rechallenge in third-line mCRC patients with RAS/BRAF WT baseline circulating tumor DNA (ctDNA). Individual data of 33 and 13 patients from CAVE and CRICKET trials that received as third-line therapy cetuximab rechallenge were collected. Overall survival (OS), Progression-free survival (PFS), Overall response rate (ORR), Stable disease (SD) >6 months were calculated. Adverse events were reported. For the whole 46 patient population, median PFS (mPFS) was 3.9 months (95% Confidence Interval, CI 3.0-4.9) with median OS (mOS) of 16.9 months (95% CI 11.7-22.1). For CRICKET patients, mPFS was 3.9 months (95% CI 1.7-6.2); mOS was 13.1 months (95% CI 7.3-18.9) with OS rates at 12, 18, and 24 months of 62%, 23%, and 0%, respectively. For CAVE patients, mPFS was 4.1 months (95% CI 3.0-5.2); mOS was 18.6 months (95% CI 11.7-25.4) with OS rates at 12, 18, 24 months of 61%, 52%, 21%, respectively. Skin rash was more frequently reported in CAVE trial (87.9% vs. 30.8%; p = 0.001), whereas a increased incidence of hematological toxicities was observed in CRICKET trial (53.8%% vs. 12.1%; p = 0.003). Third-line cetuximab rechallenge in combination with either irinotecan or avelumab in RAS/BRAF WT ctDNA mCRC patients represents a promising therapy.

Inflammation biomarkers and inflammatory genes expression in metabolically healthy obese patients

BACKGROUND AND AIMS

Obesity without metabolic alterations (Metabolically Healthy Obesity, MHO) is a condition with a risk of death and cardiovascular disease lower than that of obesity associated with metabolic alterations (Metabolically Unhealthy Obesity, MUO) and similar to that of healthy non obese individuals. Inflammation is considered as a key risk factor mediating the adverse health outcomes in obesity.

METHODS AND RESULTS

We compared circulating levels of thirteen major cytokines and adipokines and the expression profiles of fifteen pro-inflammatory and two anti-inflammatory genes in visceral and subcutaneous adipose tissue in a series of 16 MHO patients and in 32 MUO patients that underwent bariatric surgery. MHO was defined according to the most applied definition in current literature. Serum levels of a large set of major cytokines and adipokines did not differ between MHO and MUO patients (p ≥ 0.15). Analyses of the expression profile of pro-inflammatory and anti-inflammatory genes in subcutaneous and visceral adipose tissue failed to show differences between MHO and MUO patients (p ≥ 0.07). Sensitivity analyses applying two additional definitions of MHO confirmed the results of the primary analysis.

CONCLUSION

In a series of metabolically healthy obese patients neither circulating levels of major cytokines and adipokines nor the gene expression profile of a large set of pro-inflammatory and anti-inflammatory genes in subcutaneous and visceral fat differed from those in metabolically unhealthy obese patients.

Trop-2 and Nectin-4 immunohistochemical expression in metastatic colorectal cancer: searching for the right population for drugs' development

BACKGROUND

Trop-2 and Nectin-4 are transmembrane proteins overexpressed in many tumours and targets of antibody-drug conjugates (ADC). In metastatic colorectal cancer (mCRC), the role of Trop-2 and Nectin-4 has been poorly investigated.

METHODS

Tumour samples of patients randomised in the phase III TRIBE2 were assessed for Trop-2 and Nectin-4 expression.

RESULTS

Three hundred eighty-six tumours were assessed for Trop-2 expression. 90 (23%), 115 (30%) and 181 (47%) were Trop-2 high, medium and low, respectively. Patients with low Trop-2 tumours achieved longer PFS (12 versus 9.9 months, p = 0.047) and OS (27.3 versus 21.3 months, p = 0.015) than those with high/medium Trop-2 tumours. These findings were confirmed in multivariate analysis (p = 0.022 and p = 0.023, respectively). A greater OS benefit from treatment intensification with FOLFOXIRI/bevacizumab was observed in patients with high/medium Trop-2 tumours (p-for-interaction = 0.041). Two hundred fifty-one tumours were assessed for Nectin-4 expression. Fourteen (5%), 67 (27%) and 170 (68%) were high, medium and low, respectively. No prognostic impact was observed based on Nectin-4 expression and no interaction effect was reported between Nectin-4 expression groups and treatment arm.

CONCLUSIONS

In mCRC, expression levels of Trop-2 and Nectin-4 are heterogeneous, suggesting a target-driven development of anti-Trop2 and anti-Nectin-4 ADCs. Medium/high Trop-2 expression is associated with worse prognosis and higher benefit from chemotherapy intensification.

Adverse Events Associated with Encorafenib Plus Cetuximab in Patients with BRAFV600E-mutant Metastatic Colorectal Cancer: An in-depth Analysis of the BEACON CRC Study

BACKGROUND

The BRAF inhibitor encorafenib in combination with cetuximab was recently approved for patients with BRAF^V600E-mutated (BRAF^V600Emut) metastatic colorectal cancer (mCRC). Approval was based on positive results from the phase 3 BEACON CRC study in BRAF^V600Emut mCRC patients who had progressed after 1-2 previous regimens. This analysis provides a detailed examination of the adverse events (AEs) of interest (AEIs) with encorafenib+cetuximab in the BEACON study to aid gastrointestinal oncologists, given the limited experience with this combination.

MATERIALS AND METHODS

AEIs, including dermatological AEs, arthralgia/myalgia, nausea/vomiting, diarrhea, abdominal pain, fatigue/asthenia and nephrotoxicity, were examined in the doublet therapy group. Clinical characteristics associated with these AEs, AE grade, time to onset and time to resolution were also studied.

RESULTS

Safety analysis included 216/220 patients randomized to doublet therapy. The most commonly occurring AEI was dermatological toxicity (75.5%), followed by arthralgia/myalgia (56.0%) and fatigue/asthenia (56.0%). Other than nephrotoxicity (7 patients; 5/7 with Grade 3 or 4), most AEs were Grade 1 or 2. Most AEs were more common in women than men (nausea/vomiting, diarrhea, abdominal pain, dermatological AEs, and arthralgia/myalgia). Nausea/vomiting, abdominal pain and fatigue/asthenia were more common in patients aged ≥70 years. Most AEs developed early, within the first 1-2 months of treatment, and resolved within 1-2 weeks. In addition, survival outcomes were better in patients experiencing arthralgia/myalgia or dermatological toxicities.

CONCLUSION

This analysis indicated that, except for rare cases of nephrotoxicity, encorafenib+cetuximab is well tolerated in most patients, with most AEIs being mild-to-moderate in severity, occurring early and resolving rapidly.

CLINICAL TRIAL REGISTRATION

the BEACON study (ClinicalTrials.gov, NCT02928224; EudraCT, 2015-005805-35).

Impact of DNA mismatch repair proteins deficiency on number and ratio of lymph nodal metastases in colorectal adenocarcinoma

BACKGROUND

Approximately 15 % of colorectal adenocarcinomas (CRCs) are characterized by an altered expression of DNA mismatch repair (MMR) proteins (i.e. MMR deficiency [MMRd]). Lymph node ratio (LNR) represents one of the most important prognostic markers in non-advanced CRCs. No significant data are available regarding LNR distribution depending on MMR status.

PURPOSE OF THE STUDY

The aim of the present work was to compare pathological and clinical characteristics of MMRd tumors versus MMR proficient (MMRp) cases. Particular attention was paid to how these molecular sub-groups relate to the LNR.

MATERIALS AND METHODS

A mono-Institutional series of 1037 consecutive surgically treated stage I-IV CRCs were retrospectively selected and data were obtained from pathological reports. Cases were characterized for MMR/MSI status by means of immunohistochemistry or for microsatellite instability (MSI) analysis.

RESULTS

MMRd/MSI tumors (n = 194; 18.7 %) showed significant differences in comparison to MMRp lesions for sex (female prevalence 50.5 % vs 40.7 %; p = 0.013), age (74.2 vs 69.2; p < 0.001), location (right side; p < 0.001), diameter (larger than MMRp; p < 0.001), growth pattern (expansive pattern of growth; p < 0.001), peri- (p = 0.0002) and intra-neoplastic (p = 0.0018) inflammatory infiltrate, presence of perineural invasion (p < 0.001), stage (lower stage at presentation; p < 0.001), grade (higher prevalence of high-grade tumors; p < 0.001), and LNR (lower; p < 0.001).

CONCLUSIONS

MMRd/MSI tumors are a distinct molecular CRC subtype characterized by a significantly lower LNR in comparison to MMRp lesions. These data further support the prognostic impact of MMRd/MSI status in early-stage CRCs.

Extensive molecular profiling of squamous cell anal carcinoma in a phase 2 trial population: Translational analyses of the "CARACAS" study

BACKGROUND

Molecular characteristics of squamous cell anal carcinoma (SCAC) are poorly explored. Immune checkpoint inhibitors showed limited activity in phase I/II trials, but predictive and prognostic biomarkers are lacking.

PATIENTS AND METHODS

In the phase II randomised trial CARACAS (NCT03944252), avelumab alone (Arm A) or with cetuximab (Arm B) was tested in pre-treated advanced SCAC , with overall response rate being the primary end-point. On pre-treatment tumour tissue samples, we assessed Human papillomavirus status, programmed-death ligand 1 (PD-L1) expression, mismatch repair proteins expression, tumour mutational burden (TMB) and comprehensive genomic profiling by FoundationOne CDx. Tumour-infiltrating lymphocytes were characterised on haematoxylin-eosine-stained samples. Primary objective was to describe response to immunotherapy in the CARACAS trial population according to molecular and histological characteristics. Secondary objectives were to assess progression-free survival (PFS) and overall survival (OS) according to molecular biomarkers.

RESULTS

High PD-L1 (>40 with combined positive score) was significantly more frequent in patients with disease control (p = 0.0109). High TMB (>10 mutations per megabase) was related to better OS (hazard ratio (HR) = 0.09; 95%confidence interval (CI) 0.01-0.68; p = 0.019) and PFS (HR = 0.44; 95%CI = 0.15-1.27; p = 0.129). High expression of PD-L1 conferred longer OS (HR = 0.46; 95%CI = 0.19-1.08; p = 0.075) and PFS (HR = 0.42; 95%CI = 0.20-0.92; p = 0.03). Neither OS (HR = 1.30; 95%CI = 0.72-2.36; p = 0.39) or PFS (HR = 1.31; 95%CI = 0.74-2.31; p = 0.357) was affected by high (>1.2) Tumour-infiltrating lymphocytes count. High TMB and PD-L1identified patients were with significantly better OS (HR = 0.33; 95%CI = 0.13-0.81; p = 0.015) and PFS (HR = 0.48; 95%CI = 0.23-1.00; p = 0.015).

CONCLUSIONS

To our knowledge, TranslaCARACAS is the first study to document prognostic role of TMB and PD-L1 in advanced SCAC patients treated with immune checkpoint inhibitors.

Malignant ascites as a marker of peritoneal carcinomatosis burden in patients with colorectal and gastroesophageal cancer

455

Background: Malignant ascites occurs frequently in patients with gastric cancer (GC) and colorectal cancer (CRC) with peritoneal metastasis (PM). The presence of PM and malignant ascites have been independently reported to confer resistance to systemic therapy and poorer prognosis. However, the occurrence of malignant ascites as a function of increasing peritoneal carcinomatosis burden has been less studied and reported. Methods: We reviewed prospective cohorts of gastric cancer and colorectal cancer patients with PM. The first cohort was a prospective group of GCPM patients receiving bi-directional systemic and peritoneal-directed therapies (catheter-based intraperitoneal chemotherapy and/or pressurized intraperitoneal aerosol chemotherapy respectively) at a tertiary oncology center in Singapore. Clinico-pathological data, including Peritoneal Cancer Index (PCI) and the presence or absence of ascites based on diagnostic laparoscopy, was collected. To orthogonally validate the hypothesis of malignant ascites as a function of peritoneal carcinomatosis burden in gastrointestinal malignancies, we studied the relationship between ascites, PM and survival in an independent cohort of metastatic CRC patients eligible for first-line systemic treatment enrolled in two randomized clinical trials in different Italian cancer centers. Results: In the first cohort of 82 patients with GCPM, the median PCI was 19 (inter-quartile range (IQR) 8 – 26) in the group with ascites and 3 (IQR 1 – 12) in the group without ascites (p=0.005), suggesting ascites occurs with higher PM burden. The median overall survival (OS) was poorer in patients with ascites (13.4 vs 16.4 months, HR 1.6, 95% CI 0.9 – 2.8, p=0.082). The median OS in patients with PCI of <7 was 17.3 months (95% 12.0 – 22.7) and 13.8 months (95% CI 11.0 – 16.6) in those with PCI score >7. In the validation cohort of 900 CRC patients, presence of malignant ascites and PM resulted in poorer survival compared to patients with PM and no malignant ascites (HR for OS PM with ascites vs PM without ascites 2.01 (95% CI 1.37 - 2.96), p<0.001). Interestingly, those with PM and ascites had a poorer survival to those with stage IV disease without peritoneal involvement, while those with PM without ascites did not have a statistically significant difference (PM with malignant ascites vs. no peritoneal disease, HR for OS 2.14, 95% CI 1.57 – 3.01, p=0.007; PM without ascites vs no peritoneal disease, HR for OS 1.10, 95% CI 0.91 – 1.34). Conclusions: Our study of patients with colorectal or gastric cancer and peritoneal metastases suggest the presence of malignant ascites as a function of increased peritoneal carcinomatosis burden among patients with metastatic gastrointestinal malignancies, with correspondingly poorer survival outcomes.

Health-related quality of life (HRQoL) associated with fruquintinib in the global phase 3, placebo-controlled, double-blind FRESCO-2 study

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Background: The global phase 3 FRESCO-2 study, (NCT04322539) demonstrated that fruquintinib (F) vs placebo (P) significantly improved OS (HR=0.66 [95% CI: 0.55-0.80]; p<0.001) and PFS (HR=0.32 [95% CI: 0.27-0.39]; p<0.001) in heavily pre-treated patients (pts) with refractory metastatic colorectal cancer (mCRC). F safety profile was consistent with the established monotherapy profile. Here we report the HRQoL and tolerability results. Methods: Pts were randomized 2:1 to F + BSC or P + BSC. EORTC QLQ-C30 and EQ-5D-5L were assessed at baseline and on Day (D) 1 of each Cycle (C) until treatment discontinuation, and ECOG PS was assessed at baseline, D1 of each C, and D21 of C1 to C3. Least-squares mean (LSM) change from baseline to post-baseline visits and the difference between F and P in QLQ-C30 scale scores (e.g. global health status [GHS]/QoL) and EQ-5D-5L scale scores (e.g. visual analog scale [VAS]) were calculated using mixed model repeated measures approach. For each scale, the appropriate minimally important difference (MID) thresholds were determined to evaluate the improvement or deterioration. Time to deterioration (TTD), defined as worsening from baseline in scale-specific MID or death, was analyzed using Kaplan-Meier method, adjusted log-rank test, and stratified Cox PH model. QLQ-C30 and EQ-5D-5L analyses were conducted on the ITT population, and ECOG PS was on the safety population. Results: 691 pts were randomized (F: 461 vs P: 230) and 686 pts received study drug (F: 456 vs P: 230). Median treatment Cycles received (range) were 3 (1, 20) for F vs 2 (1, 13) for P. More than 79% of pts on both arms had a baseline and ≥1 post-baseline assessment for QLQ-C30, EQ-5D-5L, and ECOG PS. GHS/QoL was similar between F and P at baseline; the LSM differences between F and P were 1.7 (95% CI: -1.7, 5.0) for C2 and 1.6 (95% CI: -3.2, 6.4) for C3. At C4, <30 P patients were available. The % of patients who remained stable (MID -6.38 to <8.43) or improved (≥8.43) was numerically higher for F vs P (C2: 61.5% vs 57.1%; C3: 56.4% vs 50.9%). Median TTD was 2.1 months in F and 1.8 months in P (HR=0.9; 95% CI: 0.7-1.0; P=0.098). EQ-5D VAS was similar between F and P at baseline; the LSM differences between F and P were 0.6 (95% CI: -2.3, 3.5) for C2 and 1.4 (95% CI: -2.8, 5.6) for C3. The % of patients who remained stable (MID -7 to <7) or improved (≥7) was similar for F and P (C2: 64.6% vs 58.3%; C3: 64.2% vs 64.8%). Median TTD was 2.6 months in F and 1.9 months in P (HR=0.8; 95% CI: 0.6-0.9; P=0.001). The % of patients with ≥1-point increase from baseline in ECOG PS was 52.1% in F vs 54.0% in P. Conclusions: HRQoL is not negatively impacted by treatment with F. TTD in health utility instrument EQ-5D is improved for patients receiving F. These results, along with improved OS and PFS and favorable toxicity profile, further support F as a potential new treatment option for patients with refractory mCRC. Clinical trial information: NCT04322539 .

Prognostic Impact of Early Treatment and Oxaliplatin Discontinuation in Patients With Stage III Colon Cancer: An ACCENT/IDEA Pooled Analysis of 11 Adjuvant Trials

PURPOSE

Oxaliplatin-based adjuvant chemotherapy in patients with stage III colon cancer (CC) for 6 months remains a standard in high-risk stage III patients. Data are lacking as to whether early discontinuation of all treatment (ETD) or early discontinuation of oxaliplatin (EOD) could worsen the prognosis.

MATERIALS AND METHODS

We studied the prognostic impact of ETD and EOD in patients with stage III CC from the ACCENT/IDEA databases, where patients were planned to receive 6 months of infusional fluorouracil, leucovorin, and oxaliplatin or capecitabine plus oxaliplatin. ETD was defined as discontinuation of treatment and EOD as discontinuation of oxaliplatin only before patients had received a maximum of 75% of planned cycles. Association between ETD/EOD and overall survival and disease-free survival (DFS) were assessed by Cox models adjusted for established prognostic factors.

RESULTS

Analysis of ETD and EOD included 10,447 (20.9% with ETD) and 7,243 (18.8% with EOD) patients, respectively. Compared with patients without ETD or EOD, patients with ETD or EOD were statistically more likely to be women, with Eastern Cooperative Oncology Group performance status ≥ 1, and for ETD, older with a lower body mass index. In multivariable analyses, ETD was associated with a decrease in disease-free survival and overall survival (hazard ratio [HR], 1.61, P < .001 and HR, 1.73, P < .001), which was not the case for EOD (HR, 1.07, P = .3 and HR, 1.13, P = .1). However, patients who received < 50% of the planned cycles of oxaliplatin had poorer outcomes.

CONCLUSION

In patients treated with 6 months of oxaliplatin-based chemotherapy for stage III CC, ETD was associated with poorer oncologic outcomes. However, this was not the case for EOD. These data favor discontinuing oxaliplatin while continuing fluoropyrimidine in individuals with significant neurotoxicity having received > 50% of the planned 6-month chemotherapy.

Atezolizumab plus bevacizumab versus lenvatinib for unresectable hepatocellular carcinoma: a large real-life worldwide population

BACKGROUND AND AIMS

Atezolizumab plus bevacizumab and lenvatinib have not been compared in a randomised controlled trial. We conducted a retrospective multi-centre study to compare the clinical efficacy and safety of lenvatinib and atezolizumab with bevacizumab as a first-line treatment for patients with unresectable HCC in the real-world scenario.

METHODS

Clinical features of lenvatinib and atezolizumab plus bevacizumab patients were balanced through inverse probability of treatment weighting (IPTW) methodology, which weights patients' characteristics and measured outcomes of each patient in both treatment arms. Overall survival (OS) was the primary end-point.

RESULTS

The analysis included 1341 patients who received lenvatinib, and 864 patients who received atezolizumab plus bevacizumab. After IPTW adjustment, atezolizumab plus bevacizumab did not show a survival advantage over lenvatinib HR 0.97 (p = 0.739). OS was prolonged by atezolizumab plus bevacizumab over lenvatinib in viral patients (HR: 0.76; p = 0.024). Conversely, OS was prolonged by lenvatinib in patients with non-alcoholic steatohepatitis/non-alcoholic fatty liver disease (HR: 1.88; p = 0.014). In the IPTW-adjusted population, atezolizumab plus bevacizumab provided better safety profile for most of the recorded adverse events.

CONCLUSION

Our study did not identify any meaningful difference in OS between atezolizumab plus bevacizumab and lenvatinib. Although some hints are provided suggesting that patients with non-alcoholic steatohepatitis/non-alcoholic fatty liver disease might benefit more from lenvatinib therapy and patients with viral aetiology more from atezolizumab plus bevacizumab.

Comprehensive characterization of KRAS mutations and inter-relation with primary tumor location in colorectal cancers

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Background: The recent development of KRAS G12C inhibitors underscores the potential to target KRAS mutations. Right-sided and left-sided colon tumors (RT and LT) exhibit different molecular features. We characterize the prevalence of KRAS-variants, interrelation with primary tumor location, and association with immune biomarkers in CRC. Methods: We retrospectively reviewed CRC tumors of all stages (with known sidedness) that underwent NGS with the Tempus xT assay (DNA-seq of 648 genes at 500x coverage, full transcriptome RNA-seq). Bivariate analyses were performed to compare KRAS alterations, immune biomarkers, and co-mutations by tumor location. P-values comparing individual co-mutations between groups were adjusted for false discovery (FDR). Results: A total of 3,391 CRC were analyzed (RT: n = 442 [13%], transverse: n = 116 [3%], LT; n = 2,833 [84%]) of which 1486 (44%) tumors harbored KRAS mutations. Overall, KRAS mutations were more frequent in RT compared to transverse tumors and LT (52% vs 41% vs 43%, p<0.001, respectively). The most frequent KRAS mutation variants observed were G12D (29 %), G12V (22%), G13D (16%), and G12C (5.7%). There was no significant difference in the prevalence of KRAS variant types between LT and RT (p=0.5). Significant differences in genomic co-mutations with various KRAS variants were observed in the following genes: TP53, FBXW7, and NF1 (FDR- P<0.05). RT and transverse tumors were more likely have MSI-H and TMB-H (>10 mut/mb) status than LT (MSI-H: 18% vs 22% vs 2.2% and TMB-H (20% vs 22% vs 3%, P<0.001), respectively. CRC tumors harboring G13D variants were more likely to be associated with and MSI-H and TMB-H status (and 7.7% and 8.5%) compared to G12D (2.8 % and 3.9 %), G12V (1.8 % and 2.1%), and G12C (0% and 2.4%); P = 0.003 and 0.001. Conclusions: The most frequent KRAS mutation variants observed in CRC tumors were G12D, G12V, G13D, and G12C. There was no significant difference in the prevalence of KRAS variant types between tumors of the left vs right colon. CRC tumors that harbored G13D variants were significantly more likely to be associated with MSI-H and TMB-H status. [Table: see text]

Atezolizumab plus bevacizumab versus lenvatinib for unresectable hepatocellular carcinoma: A large, real-life, worldwide population

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Background: Atezolizumab plus bevacizumab and lenvatinib have not been compared in a randomized controlled trial. We conducted a retrospective multi-center study to compare the clinical efficacy and safety of lenvatinib and atezolizumab with bevacizumab as a first-line treatment for patients with unresectable HCC in the real-world scenario. Methods: Clinical features of lenvatinib and atezolizumab plus bevacizumab patients were balanced through inverse probability of treatment weighting (IPTW) methodology, which weights patients' characteristics and measured outcomes of each patient in both treatment arms. Overall survival was the primary endpoint. Results: The analysis included 1,341 patients who received lenvatinib, and 864 patients who received atezolizumab plus bevacizumab. After IPTW adjustment, atezolizumab plus bevacizumab did not show a survival advantage over lenvatinib HR 0.97 (p=0.739). OS was prolonged by atezolizumab plus bevacizumab over lenvatinib in viral patients (HR: 0.76; p=0.024). Conversely, OS was prolonged by lenvatinib in patients with NASH/NAFLD (HR: 1.88; p=0.014). In the IPTW-adjusted population, atezolizumab plus bevacizumab provided better safety profile for most of the recorded adverse events. Conclusions: Our study did not identify any meaningful difference in overall survival between atezolizumab plus bevacizumab and lenvatinib. Although some hints are provided suggesting that patients with NASH/NAFLD might benefit more from lenvatinib therapy and patients with viral etiology more from atezolizumab plus bevacizumab.

INFINITY: A multicentre, single-arm, multi-cohort, phase II trial of tremelimumab and durvalumab as neoadjuvant treatment of patients with microsatellite instability-high (MSI) resectable gastric or gastroesophageal junction adenocarcinoma (GAC/GEJAC)

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Background: In resectable GAC/GEJAC, MSI status is associated with better survival and potential lack of benefit from chemotherapy. Given the high responsiveness of MSI tumors to immunotherapy, neoadjuvant or definitive dual CTLA-4/PD(L)-1 inhibition may allow omission of chemotherapy or surgery. Methods: INFINITY is a multicentre, single-arm, multi-cohort phase II trial (NCT04817826) investigating the activity and safety of tremelimumab+durvalumab as neoadjuvant (Cohort 1) or definitive (Cohort 2) treatment for MSI, mismatch repair deficient (dMMR) and EBV-negative resectable GAC/GEJAC. In Cohort 1, patients (pts) received a 12-week treatment with single high dose tremelimumab 300 mg and durvalumab 1500 mg q4 weeks (T300/D) for 3 cycles followed by surgery. The primary endpoint was pCR rate (ypT0N0) with negative ctDNA after T300/D. Secondary endpoints: disease-free survival, overall survival, quality of life. Exploratory: correlation of pCR with clinical variables, PDL-1 CPS assessed by IHC 22C3, tumor mutational burden (TMB) by Foundation One, liquid biopsies and other biomarkers. Cohort 2 investigates non operative management after same treatment regimen. Results: Overall, 18 pts with MSI/dMMR resectable cT2-4 any N GAC/GEJAC were recruited in Cohort 1. One withdrew consent and 2 achieved a complete clinical-pathological response at radiology and endoscopy (ongoing) and refused surgery. Among 15 evaluable patients, 1 had disease progression and 14 underwent resection. pCR rate was 60% (9/15) and major-complete pathological response (<10% viable cells) was 80%. All pts with pCR had negative ctDNA status pre-surgery. pCR rate was 1/6 (17%) in T4 vs 8/9 (89%) in T2-3 tumors (p=0.011), whereas no correlation was found with baseline N status. PDL-1 CPS was not associated with outcomes and TMB had a non-significant trend of correlation with pCR (median TMB 26 in non-pCR vs 40 in pCR group, p=0.2). Grade≥3 immune-related AEs occurred in 3 pts of safety population (n=18): colitis, pneumonitis, liver toxicity, all resolved with high dose steroids and did not impair surgery. Two pts died after surgery for other reasons than disease or AEs, whereas no disease relapses were observed in remaining pts. QoL and additional translational analyses on RNA-seq, digital spatial profiling and ctDNA monitoring will be presented. Conclusions: Pre-operative T300/D for 3 months was safe and provided promising proof of efficacy in MSI, dMMR GAC/GEJAC pts. These results open the way to investigate NOM in pts with clinical, pathological and molecular (ctDNA minimal residual disease) complete response after T300/D. Enrollment in Cohort 2 has started after IDMC evaluation and protocol. amendment to include only pts with cT2-3 tumors confirmed at staging laparoscopy. Clinical trial information: NCT04817826 .

Impact of Lynch syndrome, BRAFV600E, and RAS mutations on outcomes in MSI/dMMR metastatic colorectal cancer (mCRC) treated with immune checkpoint inhibitors (ICI): Analysis of combined international cohorts

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Background: ICI have demonstrated efficacy in patients (pts) with MSI/dMMR mCRC . Lynch (LS) vs sporadic (Sp) status, BRAFV600E and RAS mutations (mt) are known factors of clinical and molecular heterogeneity in this population. We aimed to evaluate the prognostic value of these parameters in ICI-treated MSI mCRC pts. Methods: Pts are drawn from international cohorts (France, Italy, Spain, and USA). Pts were considered to have cancer linked to LS only in case of determined germline mutation and Sp in case of loss of MLH1/PMS2 protein expression associated with BRAF V600E mutation and/or hypermethylation of MLH1 promoter, or in case of biallelic somatic mutations of MMR genes. Survival analyses: progression-free survival (PFS) per iRECIST criteria and overall survival (OS) were adjusted on prognostic modifiers, selected on unadjusted analysis (p < 0.2) in case of limited number of events. Results: On the 466 pts included, 112 (24%) received ICI in first line, 305 (65%) received anti-PD1 alone, 161 (35%) anti-PD1 plus anti-CTLA4, 129 (29%) had BRAFV600Emt and 153 (34%) RASmt. Median follow-up was 24.0 months. In adjusted analysis of the whole population (n=466; 186 PFS events and 143 OS events), no association with PFS and OS was observed for BRAFV600E mt (PFS HR 1.20 [0.80 to 1.79], p=0.372; OS HR 1.06 [0.66 to 1.70], p= 0.811) and RASmt (PFS HR 0.93 [0.64 to 1.36], p= 0.712; OS HR 0.75 [0.48 to 1.17] p= 0.202). Adjusting factors were age, ECOG status, number of prior chemotherapies, treatment type (bi vs monotherapy), sidness (right vs left + rectum), primary tumor surgery. Concerning the population with determined Lynch status (n= 242; 83 PFS events and 54 OS events), PFS results are displayed. The analysis of impact of LS was not adjusted on BRAFV600E mutational status due to collinearity. In adjusted analysis, LS improved PFS compared with Sp (HR = 0.49, 95%CI (0.25 to 0.96), p = 0.036). Adjusted HR for OS was 0.56 without reaching significance 95%CI (0.25 to 1.22), p = 0.143. Conclusions: In this analysis of ICI-treated MSI/dMMR mCRC pts, RAS/BRAFV600E mutations are not associated with survival while Lynch syndrome pts demonstrated improved PFS. [Table: see text]

BREAKWATER safety lead-in (SLI): Encorafenib (E) + cetuximab (C) + chemotherapy for BRAFV600E metastatic colorectal cancer (mCRC)

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Background: Based on the phase 3 BEACON study (NCT02928224), BRAF inhibitor (i) encorafenib (E) + EGFRi cetuximab (C) was approved for the treatment (tx) of previously treated patients (pts) with BRAFV600E mCRC, with mPFS of 4.3 months (mo) and ORR of 19.5%. In the phase 2 ANCHOR study (NCT03693170), mPFS was 5.8 mo and ORR was 48% for 1L EC + binimetinib in BRAFV600E mCRC. To further assess 1L approaches, the ongoing phase 3 BREAKWATER study (NCT04607421) is evaluating EC ± chemotherapy vs standard-of-care chemotherapy in BRAFV600E mCRC. Here, we present updated safety and antitumor activity data as well as biomarker data from the BREAKWATER SLI. Methods: Inclusion criteria for the SLI were BRAFV600E mCRC (blood or tumor tissue), ≤1 prior systemic tx for mCRC, and ECOG PS 0/1. Pts previously treated with BRAFi/EGFRi or both oxaliplatin and irinotecan were excluded. Pts received E 300 mg daily + C 500 mg/m2 every 2 weeks (Q2W) + either mFOLFOX6 Q2W (n=27) or FOLFIRI Q2W (n=30) in 28-day cycles until disease progression or unacceptable toxicity. The primary endpoint was frequency of dose-limiting toxicities. Secondary endpoints included safety, pharmacokinetics, and antitumor activity. Exploratory endpoints included evaluation of plasma (circulating tumor DNA [ctDNA] genomic profiling) and tumor tissue (molecular profiling) biomarkers. Updated results from the BREAKWATER SLI will be presented, including overall safety and tolerability and antitumor activity. Biomarker data, including changes from baseline in BRAFV600E ctDNA following treatment (Cycle 1 Day 15, Cycle 2 Day 15 and Cycle 7 Day 1) and MSI status of pts, will also be presented. Expected conclusions will be included in the final abstract. Clinical trial information: NCT04607421 .