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TPS3644 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 IIB, IIC, and III 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 v serial ctDNA monitoring. Patients who are ctDNA+ post-operatively, or with serial monitoring (Cohort B), will be randomized to FP+Ox v more intensive AC with addition of irinotecan (I) for 6 mos. One cycle of chemotherapy is allowed while awaiting ctDNA testing results for cohort assignment. The primary endpoints for Cohort A are time to ctDNA+ status (phase II) and disease-free survival (DFS) (phase III) in the immediate v delayed AC arms. The primary endpoint for Cohort B is DFS in the FP+Ox v 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 with CCTG sites joining in August 2023. Current accrual (as of 1-27-2025): 647/1,912. NCT: 05174169. Support: U10 CA180868, -180822; -180888; UG1 CA189867; Natera, Inc. Clinical trial information: NCT05174169 .

TPS3634 Background: For patients with oligometastatic colorectal cancer (CRC), aggressive local therapy of isolated metastases, particularly in the liver, has been associated with long-term progression-free and overall survival (OS) primarily based on retrospective evidence. However, in patients with limited metastatic CRC that is deemed inoperable or those with additional disease outside of the liver or lungs, the role of local ablative therapies, including microwave ablation (MWA) and stereotactic body radiation therapy (SBRT), to render patients disease free is less clear. Despite the long history of treating oligometastatic CRC with local therapy, which is largely provider biased, questions remain regarding the benefit of extending the paradigm of metastatic directed therapy to patients with more extensive disease. This trial seeks to use a pragmatic multimodality approach that mirrors the current clinical dilemma. This study is designed to evaluate the safety and efficacy of adding total ablative therapy (TAT) of all sites of disease to standard of care systemic treatment in those with limited metastatic CRC. Methods: A022101/NRG-GI009 is a National Clinical Trials Network randomized phase III study planned to enroll 364 patients with newly diagnosed metastatic CRC (BRAF wild-type, microsatellite stable) without peritoneal metastasis or liver-only disease on baseline imaging. Patients receive first-line systemic therapy for 12-39 weeks. Patients with ≤4 sites of metastatic disease following initial systemic therapy that are amenable to any combination of surgical resection, MWA, and/or SBRT are then randomized 1:1, stratified by number of metastatic organ sites (1-2 vs. 3-4), timing of metastatic disease diagnosis (de novo vs. secondary), and presence of metastatic disease outside the liver/lungs in at least 1 site. Patients in Arm 1 will receive TAT consisting of treatment of all metastatic sites with SBRT, MWA, and/or surgical resection followed by standard of care systemic therapy. Patients in Arm 2 will continue with standard of care systemic therapy alone. The primary endpoint is OS. Secondary endpoints include event-free survival, treatment-related toxicities, and local recurrence with exploratory biomarker analyses. The study needs 346 evaluable patients combined in the 2 arms to demonstrate an improvement in OS with a hazard ratio of 0.7 to provide 80% power with a one-sided alpha of 5%. The trial utilizes a group sequential design with two interim analyses (25% and 50% of events) for futility. The trial activated in January 2023 and recruitment is ongoing. Support: U10CA180821, U10CA180882; https://acknowledgments.alliancefound.org. U10CA180820 (ECOG-ACRIN); U10CA180868 (NRG); U10CA180888 (SWOG); Clinical trial information: NCT05673148 .

e24024 Background: Patients with active cancer undergoing trans catheter aortic valvular replacement (TAVR) face a higher risk of adverse outcomes due to the interplay between cancer and cardiovascular disease. Although TAVR is increasingly used in high-risk populations, data on outcomes for these patients remain limited. This systematic review and meta-analysis aim to evaluate the clinical outcomes associated with TAVR in patients with active cancer compared to non-cancer controls, providing insights to inform clinical decision-making in this unique group. Methods: A systematic search of major databases (PubMed, Embase, OVID, Web of Science, Scopus) was conducted to identify studies comparing clinical outcomes of TAVR between patients with active cancer and those without cancer. Key outcomes included measures of mortality, procedural complications, and post-procedure adverse events. The Mantel-Haenszel method was used for pooled analysis, applying random-effects or fixed-effects modeling based on heterogeneity assessed by Higgins I². Statistical significance was set at a p-value < 0.05. Results: Twelve studies involving 5,73,192 patients (67,684 active cancer, 505508 control) were included. Patients with active cancer undergoing TAVR have significantly higher risks of short-term mortality (OR 1.31, 95% CI [1.15, 1.49], p < 0.0001), long-term mortality (OR 2.24, 95% CI [1.85, 2.70], p < 0.0001), and major bleeding complications (OR 1.80, 95% CI [1.68, 1.92], p < 0.0001). There were no statistically significant differences in cardiovascular mortality (OR 1.33, 95% CI [0.94, 1.89], p = 0.11), myocardial infarction (OR 1.60, 95% CI [0.82, 3.11], p = 0.17), stroke (OR 0.61, 95% CI [0.28, 1.35], p = 0.22), AKI (OR 0.92, 95% CI [0.49, 1.73], p = 0.80), or the need for permanent pacemaker implantation (OR 1.12, 95% CI [0.85, 1.48], p = 0.42). Conclusions: Patients with active cancer undergoing TAVR face significantly higher risks of mortality and major bleeding compared to non-cancer controls. However, the risks of cardiovascular mortality, MI, stroke, AKI, and the need for permanent pacemaker implantation are comparable to those of non-cancer controls. Careful risk assessment and management are crucial for optimizing outcomes in this vulnerable population, and further studies are needed to refine treatment strategies. Odds ratios of all outcomes. Outcomes OR Confidence Interval (95% CI) p-value Short term mortality 1.31 [1.15, 1.49] < 0.0001 Long term mortality 2.24 [1.85, 2.70] < 0.00001 Major bleeding 1.8 [1.68, 1.92] < 0.00001 Cardiovascular mortality 1.33 [0.94, 1.89] 0.11 Myocardial Infarction 1.6 [0.82, 3.11] 0.17 Stroke 0.61 [0.28, 1.35] 0.22 Acute Kidney Injury 0.92 [0.49, 1.73] 0.8 Need for permanent pacemaker implantation 1.12 [0.85, 1.48] 0.42

e19503 Background: The uptake of BCMA directed ADCs in MM has been hindered by ocular toxicity. Belantamab mafodotin (BM) and MEDI2228 (MEDI) are BCMA directed monoclonal antibodies conjugated to the microtubule inhibitor, monomethyl auristatin F and the alkylator, pyrrolobenzodiazepine, respectively. Differences in the ADCs payload, antibody specificity and linker stability influence ocular toxicity. We investigated the patterns of ocular toxicity and tolerability of BCMA directed ADC therapy. Methods: Retrospective study of MM patients who commenced treatment with a commercial or investigational BCMA directed ADC at the Mayo Clinic between 2019-22. Results: 111 patients were included, the median age was 69 and median follow up 40 months. The median number of prior treatments was 6, 87% of patients were triple class refractory, 50% penta class refractory, 14% had prior BCMA directed therapy and 24% had extraosseous disease. Treatments included BM (n=56, 50%), BM in combination with other MM therapy (n=12, 11%) and MEDI (n=43, 39%). The overall response rate was 30% for BM and 44% for MEDI. The median OS and PFS for BM was 8 and 2 months, the median OS and PFS for MEDI was 11 and 5 months. The median number of ADC cycles was 2.5. Ocular toxicity is summarized in the table 1. Keratopathy was more common with BM (p=0.004). Only 4 MEDI patients developed keratopathy, all grade 1 and associated with dry eyes and/or photophobia. In contrast, 60% of BM patients developed keratopathy (13% grade 3-4 keratopathy). The median time to keratopathy onset was 1 month with BM, and 2.8 with MEDI. The median time until keratopathy was 4.6 months for BM. Loss of best-corrected visual acuity (VA) was significantly more common with BM (p<0.001). The median time to any decline in VA was 1.5 months for BM and 2.3 for MEDI. The median time until VA returned to baseline was 2.4 months for BM and 2.3 for MEDI. The frequency of dose delays for ocular toxicity was comparable between ADCs, as was the number of dose reductions (16% BM vs. 12% MEDI, p=0.5). The most common reasons for treatment discontinuation were progression or death (BM=69%, MEDI=44%) and ocular toxicity (BM=18%, MEDI=30%). Conclusions: Treatment interruptions, dose reductions and drug discontinuation are common with BCMA directed ADC therapy. Further research to optimize the administration schedule of these agents is warranted. BM and MEDI produce distinct patterns of ocular side effects, namely keratopathy and reduced VA with the former, and photophobia and dry eyes with the latter. BM N = 68 MEDI N = 43 p-value 2 Prophylactic steroid eye drops 4 (6%) 28 (68%) <0.001 Prophylactic lubricant eye drops 42 (63%) 33 (80%) 0.051 Max grade keratopathy 0.004 1-2 29 (47%) 4 (19%) 3-4 8 (13%) 0 (0%) VA equal or worse than 20/40 26 (68%) 6 (20%) <0.001 Days of ADC treatment 59 (33, 167) 68 (41, 105) 0.9 Dose delay for ocular toxicity 19 (28%) 8 (19%) 0.2 n (%); Median (IQR); 2 Chisq test; Wilcoxon rank sum.

BACKGROUND: It is uncertain whether antiplatelets or anticoagulants are more effective in preventing early recurrent stroke in patients with cervical artery dissection. Following the publication of the observational Antithrombotic for STOP-CAD (Stroke Prevention in Cervical Artery Dissection) study, which has more than doubled available data, we performed an updated systematic review and meta-analysis comparing antiplatelets versus anticoagulation in cervical artery dissection. METHODS: The systematic review was registered in PROSPERO (CRD42023468063). We searched 5 databases using a combination of keywords that encompass different antiplatelets and anticoagulants, as well as cervical artery dissection. We included relevant randomized trials and included observational studies of dissection unrelated to major trauma. Where studies were sufficiently similar, we performed meta-analyses for efficacy (ischemic stroke) and safety (major hemorrhage, symptomatic intracranial hemorrhage, and death) outcomes using relative risks. RESULTS: We identified 11 studies (2 randomized trials and 9 observational studies) that met the inclusion criteria. These included 5039 patients (30% [1512] treated with anticoagulation and 70% [3527]) treated with antiplatelets]. In meta-analysis, anticoagulation was associated with a lower ischemic stroke risk (relative risk, 0.63 [95% CI, 0.43 to 0.94]; P =0.02; I 2 =0%) but higher major bleeding risk (relative risk, 2.25 [95% CI, 1.07 to 4.72]; P =0.03, I 2 =0%). The risks of death and symptomatic intracranial hemorrhage were similar between the 2 treatments. Effect sizes were larger in randomized trials. There are insufficient data on the efficacy and safety of dual antiplatelet therapy or direct oral anticoagulants. CONCLUSIONS: In this study of patients with cervical artery dissection, anticoagulation was superior to antiplatelet therapy in reducing ischemic stroke but carried a higher major bleeding risk. This argues for an individualized therapeutic approach incorporating the net clinical benefit of ischemic stroke reduction and bleeding risks. Large randomized clinical trials are required to clarify optimal antithrombotic strategies for management of cervical artery dissection.

TPS3650 Background: A total neoadjuvant therapy (TNT) approach improves compliance with chemotherapy and increases rates of tumor response compared to neoadjuvant chemoradiation (CRT) alone in those with locally advanced rectal cancer. Recent data indicate that optimal sequencing of TNT involves consolidation (rather than induction) chemotherapy to improve complete response rates. The use of FOLFIRINOX has shown to improve response and outcomes compared to CRT and surgery alone. Data have also shown that patients with clinical complete response (cCR) after TNT may be managed with a watch and wait approach (WW) instead of preemptive total mesorectal resection (TME). However, the optimal consolidation chemotherapy regimen to improve cCR rates has not been established, and a randomized clinical trial has not robustly evaluated cCR as a primary endpoint. We designed this NCI-sponsored study of chemotherapy intensification to address this and to increase cCR rates, provide opportunity for organ preservation, and survival outcomes. Methods: In this multigroup randomized, seamless phase II/III trial (1:1), up to 760 patients with LARC, T4N0, any T with node positive disease (any T, N+) or T3N0 requiring abdominoperineal resection or coloanal anastomosis and distal margin within 12 cm of anal verge will be enrolled. Stratification factors include tumor stage (T4 vs T1-3), nodal stage (N+ vs N0) and distance from anal verge (0–4; 4–8; 8–12 cm). Patients will be randomized to receive neoadjuvant long-course chemoradiation (LCRT) followed by consolidation doublet (mFOLFOX6 or CAPOX (control arm)) or triplet chemotherapy (FOLFIRINOX (experimental arm)) for 3–4 months. LCRT in both arms involve 4500 cGy in 25 fractions over 5 weeks +900 cGy boost in 5 fractions with a fluoropyrimidine. Patients will undergo assessment 8–12 (±4) weeks post-TNT completion. The primary endpoint for the phase II portion will compare cCR between treatment arms. A total number of 312 patients (156 per arm) will provide statistical power of 90.5% to detect a 17% increase in cCR rate, at a one-sided alpha = 0.048. The primary endpoint for the phase III portion will compare disease-free survival (DFS) between arms. A total of 285 DFS events will provide 85% power to detect an effect size of hazard ratio 0.70 at a one-sided alpha of 0.025, requiring enrollment of 760 patients (380 per arm). Secondary objectives include overall survival, organ preservation time, time to distant metastasis, and adverse event rates. This study has accrued 587 patients as of January 2025, and is investigating exploratory correlatives (e.g., ctDNA). Support: U10CA180821, U10CA180882, U24 CA196171. https://acknowledgments.alliancefound.org. Clinicaltrials.gov ID: NCT05610163. Clinical trial information: NCT05610163 .

e19524 Background: Carfilzomib, a second-generation proteasome inhibitor, has emerged as one of the therapeutic agents in the treatment of relapsed or refractory multiple myeloma (MM). Despite its known cardiotoxicity, real-world data on its long-term cardiovascular outcomes remain limited. This study aimed to evaluate the real-world cardiovascular outcomes in patients with relapsed or refractory MM treated with carfilzomib. Methods: We utilized the TriNetX network to identify patients (≥18 years old) with relapsed or refractory MM between January 1, 2014, and January 1, 2019. We further categorized the patients into two groups: patients exposed to carfilzomib and patients not exposed to carfilzomib. Inclusion in the carfilzomib group required exposure to carfilzomib during the 5-year study period. Propensity score matching was performed to match these two groups based on comorbidities, medications, baseline hemoglobin A1c, low-density lipoprotein, and left ventricular ejection fraction to produce two comparable cohorts. The study outcomes were cardiovascular outcomes, including acute heart failure, acute myocardial infarction, cerebrovascular accident, acute venous thromboembolism, all-cause hospitalization, and all-cause mortality over the 5-year follow-up duration. Results: A total of 151,802 patients with relapsed or refractory MM were identified, including 6,386 patients (mean age 64.8 ± 10.6 years) who were exposed to carfilzomib and 145,416 patients (mean age 66.1 ± 12.7 years) who were not. After propensity score matching, there were 4,559 (65.3 ± 10.8 years of age, 44.7% female, 18.2% African American [AA]) patients who were exposed to carfilzomib and 4,559 patients who were not (65.2 ± 12.2 years of age, 45.1% female, 17.0% AA). Exposure to carfilzomib was associated with higher odds of acute heart failure (adjusted odds ratio [aOR]: 1.61; 95% CI: 1.48-1.77, P < 0.001), acute myocardial infarction (aOR: 1.24; 95% CI: 1.03-1.48, P = 0.020), cerebrovascular accident (aOR: 1.97; 95% CI: 1.47-2.64, P < 0.001), acute venous thromboembolism (aOR: 1.79; 95% CI: 1.58-2.03, P < 0.001), all-cause hospitalizations (aOR: 1.91; 95% CI: 1.75-2.09, P < 0.001), and all-cause mortality (aOR: 1.97; 95% CI: 1.80-2.16, P < 0.001). Conclusions: Patients with relapsed or refractory MM who were exposed to carfilzomib had poorer cardiovascular outcomes compared to those who did not.

e19521 Background: Blindedindependent central review (BICR) committees are often established for oncology trials to assessbestoverall response (BOR), while real-world (RW) studies typically rely on physician-assessed responses. To emulate clinical trial rigor, a BICR committee was implemented in the R5458-ONC-21101 RW data-derived external control arm study (NCT05673967) to evaluate BOR using International Myeloma Working Group (IMWG) criteria. A pre-specified concordance analysis compared BOR assessments between the BICR committee and treating site physicians. Methods: RW data were obtained from chart reviews at 15 participating International Myeloma Foundation IMWG sites. The BICR committee, comprised of three multiple myeloma experts, evaluated BOR through consensus voting. Per protocol, the committee reviewed case report forms consisting of data on serum and urine myeloma protein and free light chain levels; and, where available, bone marrow plasma cell percentage, presence of plasmacytomas, and bone lesion changes. Concordance between BICR- and physician-assessed BOR was evaluated for objective response rate defined as ≥partial response (PR), ≥very good partial response (VGPR), ≥complete response (CR), and stringent complete response (sCR), with non-evaluable responses excluded from the analysis. Cohen’s kappa (κ) was used to measure agreement, with values >0.6 indicating strong concordance. 1 Results: Of 279 evaluable lines of therapy from 203 patients (Table), the BOR of ≥PR was 45.2% by BICR assessment and 42.3% by treating physicians (κ=0.622). Concordance improved for BOR of ≥VGPR (22.2% by BICR vs 24.7% by treating physicians; κ=0.731) but was low for BOR of ≥CR (3.9% vs. 10.8%; κ=0.508) and sCR (1.1% vs. 4.7%; κ=0.364). Conclusions: BICR- and physician-assessed responses showed strong concordance for BOR of ≥PR and ≥VGPR. However, as expected, lower concordance for ≥CR and sCR was observed, as evaluation of CR per IMWG criteria requires a bone marrow biopsy, which is rarely performed in clinical practice. While the reliability of CR and sCR in RW data is less certain, these results suggest that BOR of ≥VGPR or ≥PR may be reliably ascertained in academic settings based on treating physician evaluations. 1. Landis JR, Koch GG. Biometrics 1977;33(1):159–74. Clinical trial information: NCT05673967 . Agreement of BICR- and physician-assessed responses. BICR assessed Physician assessed Observed agreement, % Cohen’s kappa* Number of evaluable lines of therapy 279 279 - - ≥PR, n (%) 126 (45.2) 118 (42.3) 81.4 0.622 ≥VGPR, n (%) 62 (22.2) 69 (24.7) 90.3 0.731 ≥CR, n (%) 11 (3.9) 30 (10.8) 93.2 0.508 sCR, n (%) 3 (1.1) 13 (4.7) 96.4 0.364 *A kappa value >0.6 indicates strong concordance. 1

e19515 Background: The prevalence of diabetes mellitus (DM) is significantly higher in patients with multiple myeloma (MM) compared to the general population. DM has been associated with worse outcomes in MM, including reduced overall survival and increased mortality. The impact of diabetes in patients with MM is further compounded by cardiotoxicity from proteasome inhibitors and the increased thromboembolic risk linked to immunomodulatory agents. Given the potential benefits of sodium-glucose cotransporter-2 (SGLT2) inhibitors, we hypothesized that their use in MM patients with DM could improve clinical outcomes and mitigate adverse events in this population. Methods: We utilized the TriNetX network to identify patients (≥18 years old) with MM and DM between January 1, 2013, and January 1, 2019. We categorized the patients into SGLT2 inhibitors users and SGLT2 inhibitors users. Inclusion in the SGLT2 inhibitors group required exposure to SGLT2 inhibitors for at least 1 year. 1:1 Propensity score matching was performed to match these two groups based on comorbidities, medications, baseline hemoglobin A1c, low-density lipoprotein, and left ventricular ejection fraction to produce two comparable cohorts. The study outcomes include all-cause mortality, all-cause hospitalization, acute venous thromboembolism (VTE), acute heart failure (HF), acute myocardial infarction (MI), cardiac arrhythmia, and cardiac arrest over the 5-year follow-up duration. Results: A total of 43,078 patients were identified, including 3,640 SGLT2 inhibitors users and 39,438 non-SGLT-2 inhibitors users. After 1:1 propensity-score matching, there were 3,379 SGLT-2 inhibitor users (68.9 ± 10.3 years of age, 38.0% female, 23.9% African American [AA]) and 3,379 non-SGLT-2 inhibitor users (68.9 ± 11.0 years of age, 35.9% female, 22.2% AA). SGLT-2 inhibitors users were associated with lower rates of all-cause mortality (odds ratio [OR]: 0.34, 95% confidence interval [CI]: 0.30-0.39) and all-cause hospitalization (OR: 0.52, 95% CI: 0.47-0.58). Lower odds of acute VTE (OR: 0.59, 95% CI: 0.49-0.70), acute HF (OR: 0.89, 95% CI: 0.81-0.98), acute MI (OR: 0.81, 95% CI: 0.69-0.95), cardiac arrhythmia (OR: 0.82, 95% CI: 0.70-0.97), and cardiac arrest (OR: 0.57, 95% CI: 0.44-0.74) were reported among SGLT-2 inhibitors users compared to non-SGLT2 inhibitor users. Conclusions: Our study revealed that only 8.4% of patients with DM and MM were prescribed an SGLT-2 inhibitor. Our study also demonstrated that SGLT2 inhibitor use was associated with lower odds of all-cause mortality and hospitalization, reduced risk of VTE, and favorable cardiovascular outcomes in this patient population.

3624 Background: Increasing chemotherapy completion and reducing chemotherapy adverse events (AE) are critical to improve survival after colon cancer diagnosis. Sex, as a biological variable, may impact chemotherapy treatment differently, and thus further investigation is needed to examine sex differences in chemotherapy completion and adverse events among patients with colon cancer. Methods: Among an NCI-sponsored trial conducted among patients with stage III colon cancer (CALGB/SWOG 80702), all patients received standard adjuvant chemotherapy FOLFOX (fluorouracil, leucovorin, and oxaliplatin). To signal chemotherapy completion, we utilized relative dose intensity (RDI) calculated as the ratio of the delivered dose intensity to planned dose intensity; and reduced RDI (RDI <85%) was considered as a clinically significant deviation from standard FOLFOX. From clinicians’ records of NCI’s Common Terminology Criteria for Adverse Events (CTCAE), we primarily focused on clinically significant AE such as neutrophils decrease, nausea, platelets decrease, hypertension, peripheral neuropathy, diarrhea, fatigue, gastritis, creatinine increase, gastric ulcer, myocardial ischemia, and cerebral ischemia; and severe AE was defined as the occurrence of any above AE with CTCAE grade ≥3. Using multivariable logistic regression that adjusted for body surface area (BSA) and other clinicopathological confounders, we estimated adjusted odds ratios (OR) for the associations of sex with reduced RDI and severe AE. Results: Of 2201 patients, mean (standard deviation [SD]) age was 60.9 (10.9) years, 1019 (46.3%) were female, 1750 (79.5%) were White, 172 (7.8%) were Hispanic, 964 (43.8%) experienced reduced RDI, and 1156 (52.5%) had severe adverse events. Compared to males, females were at significantly higher risks of experiencing reduced RDI (OR [95% CI]: 1.57 [1.27-1.93], P <0.001) and severe AE (OR [95% CI]: 1.73 [1.41-2.12], P <0.001). Conclusions: Our findings suggested females are more likely than men to experience reduced RDI and severe AE during colon cancer chemotherapy. Clinical Impact: In the era of precision medicine, sex (as a biological variable) should be considered in optimizing colon cancer chemotherapy to improve completion and reduce toxicities. Clinical trial information: NCT01150045 .