Citations

Importance In a phase 2 randomized clinical trial, high-dose vitamin D 3 added to standard treatment improved progression-free survival (PFS) compared with standard-dose vitamin D 3 in patients with metastatic colorectal cancer (mCRC). Objective To determine if high-dose vitamin D 3 added to standard chemotherapy improves outcomes in patients with previously untreated mCRC. Design, Setting, and Participants Double-blind phase 3 randomized clinical trial enrolling 455 patients with previously untreated mCRC, conducted in the US through the National Clinical Trials Network from October 2019 to December 2022 (database freeze: July 15, 2024). Interventions mFOLFOX6 (modified FOLFOX6 [5-fluorouracil, leucovorin, oxaliplatin]) or FOLFIRI (5-fluorouracil, leucovorin, irinotecan) plus bevacizumab every 2 weeks with either high-dose vitamin D 3 (8000 IU daily × 14 days as loading dose followed by 4000 IU daily) or standard-dose vitamin D 3 (400 IU daily) until disease progression, intolerable toxicity, or withdrawal of consent. Main Outcomes and Measures The primary end point was PFS assessed by the unstratified log-rank test. Secondary end points included objective response rate, overall survival, and toxicity. Prespecified subgroup analyses of PFS were performed according to known prognostic factors. Results Among 455 randomized patients (median age, 59 years; 181 [40%] female) with median follow-up 20 months, the median PFS for high-dose vitamin D 3 (n = 228) was 11.8 months (95% CI, 10.3-13.3) vs 10.3 months (95% CI, 9.4-12.2) for standard-dose vitamin D 3 (n = 227) (1-sided log-rank P = .25). There were no significant differences in objective response rate between high-dose and standard-dose vitamin D 3 (51% [95% CI, 44%-58%] vs 44% [95% CI, 37%-50%], respectively; P = .12), or in overall survival (median, 25.6 vs 27.0 months; 1-sided log-rank P = .66). There were no clinically meaningful differences in the most common grade 3 or greater adverse events between the high- and standard-dose groups, including neutropenia (n = 67 [32%] vs n = 62 [30%]) and hypertension (n = 42 [20%] vs n = 49 [23%]) or in incidence of vitamin D–associated toxicities. Conclusions and Relevance Among patients with previously untreated mCRC, addition of high-dose vitamin D 3 , vs standard-dose vitamin D 3 , to standard chemotherapy plus bevacizumab did not improve PFS. Trial Registration ClinicalTrials.gov Identifier: NCT04094688

TPS3675 Background: Multi-agent chemotherapy regimens (eg, mFOLFOX6) ± anti-vascular endothelial growth factor (VEGF) or anti-epidermal growth factor regimens are currently the standard of care for patients (pts) with mCRC without targetable mutations. However, the 5-year survival rate remains low at approximately 16% (SEER, 2025). The addition of biological therapies (eg, bevacizumab [bev], an anti-VEGF monoclonal antibody) to immune checkpoint inhibitors (ICIs) has demonstrated a synergistic antitumor effect in solid tumors. However, ICI monotherapy has limited activity in mismatch repair proficient (pMMR)/microsatellite stable (MSS) mCRC. Simultaneous bispecific targeting of programmed death 1 (PD-1) and VEGF in conjunction with cytotoxic chemotherapy has the potential to enhance antitumor activity. PF-08634404 is a fully human immunoglobulin G4 (IgG4) bispecific antibody targeting PD-1 and VEGF. A phase 2 study of PF-08634404 with XELOX or mFOLFOX6 demonstrated promising antitumor activity with a manageable safety profile in first-line (1L) mCRC (Xu X, ESMO 2025; Abstract 796P). Methods: Symbiotic-GI-03 (NCT07222800) is an ongoing, double-blind, randomized, phase 3 study evaluating the efficacy and safety of 1L PF-08634404 + mFOLFOX6 vs bev + mFOLFOX6. Inclusion criteria are age ≥18 y; mCRC with measurable disease per RECIST 1.1; no prior systemic therapy for metastatic disease; ECOG PS 0 or 1; and adequate hematologic, hepatic, and renal function. Pts with BRAF V600E-mutant or mismatch repair deficient (dMMR)/microsatellite instability-high (MSI-H) CRC, active central nervous system metastases, or clinically significant risk of hemorrhage/fistula will be excluded. Approximately 800 pts will be randomized 1:1 to receive PF-08634404 + mFOLFOX6 or bev + mFOLFOX6 until disease progression, unacceptable toxicity, withdrawal of consent, or death. Randomization will be stratified by region (North America, Europe, or rest of world), RAS status (mutant or wildtype), and presence of liver metastasis (yes or no). The dual primary endpoints are progression-free survival (PFS) by blinded independent central review and overall survival; for each, a stratified log-rank test will be used to compare arms. Hazard ratios with corresponding 2-sided 95% CIs will be estimated using a stratified Cox proportional hazards model, and medians will be estimated using the Kaplan-Meier method with corresponding 2-sided 95% CIs calculated using the log(-log) method. Secondary endpoints include PFS by investigator, objective response rate, duration of response, PFS after next-line therapy, safety/tolerability, pharmacokinetics, immunogenicity, and patient-reported outcomes. Enrollment began in December 2025. Clinical trial information: NCT07222800 .

Abstract Background: Adhering to 2018 World Cancer Research Fund (WCRF)/American Institute for Cancer Research (AICR) Cancer Prevention Recommendations is reportedly associated with better survival among long-term colon cancer survivors (likely affected by immortal time bias). Thus, it is important to validate survival benefits by assessing adherence shortly after diagnosis, and further investigation is needed to examine its association with chemotherapy outcomes. Methods: Using an NCI-sponsored adjuvant chemotherapy trial conducted in patients with stage III colon cancer (CALGB/SWOG 80702; NCT01150045), we included 1,666 patients who returned valid Willett food frequency questionnaires (FFQ) at chemotherapy initiation and derived WCRF/AICR scores accordingly (higher score suggesting higher adherence). The primary outcome was disease-free survival (time from FFQ completion to recurrence or death), and secondary outcomes were reduced relative dose intensity (RDI; <85% suggesting worse completion) and severe toxicities (grade ≥3 for any chemotherapy-related toxicity). To estimate the associations of WCRF/AICR scores (quartiles) with survival and chemotherapy outcomes, we conducted multivariable Cox proportional hazards regression for disease-free survival and multivariable logistic regression for reduced RDI and severe toxicities. Results: Compared to those in the lowest quartile of the WCRF/AICR score, patients in the highest quartile had significantly better disease-free survival (hazard ratio: 0.75 [0.58, 0.98], Ptrend = 0.02) and lower risk of reduced RDI (odds ratio [OR]: 0.74 [0.54, 1.00], Ptrend = 0.03), but not for severe toxicities (OR: 1.24 [0.93, 1.67], Ptrend = 0.11). Conclusions: In patients with stage III colon cancer, higher adherence to WCRF/AICR recommendations was associated with better survival and chemotherapy completion, but not for severe toxicities. Funding: https://acknowledgments.alliancefound.org Citation Format: En Cheng, Chao Ma, Qian Shi, Anthony F. Shields, Peter T. Campbell, Ardaman P. Shergill, Katherine A. Guthrie, Felix Couture, Philip Kuebler, Pankaj Kumar, Benjamin Tan, Smitha S. Krishnamurthi, Kimmie Ng, Eileen M. O'Reilly, Justin C. Brown, Philip A. Philip, Jeffrey A. Meyerhardt. Associations of WCRF/AICR recommendations with survival and chemotherapy outcomes in colon cancer: CALGB/SWOG 80702 (Alliance) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 5038.

Abstract Background The associations between different types of diabetes, characterized by distinct pathophysiology and genetic architecture, and pancreatic ductal adenocarcinoma (PDAC) risk are not understood. Methods We investigated associations of genetic susceptibility to type 2 diabetes (T2D), 8 T2D mechanistic clusters, type 1 diabetes (T1D), and maturity-onset diabetes of the young (MODY) with PDAC risk. We used genome-wide association study (GWAS) summary-level statistics for T2D (242 283 cases, 1 569 734 controls), T1D (18 942 cases, 501 638 controls), and PDAC (10 244 cases and 360 535 controls) in individuals of European ancestry. Results Two-sample Mendelian randomization (MR) using the Robust Adjusted Profile Score (MR-RAPS) method indicated that genetically predicted T2D was associated with PDAC risk (OR = 1.10; 95% CI = 1.05 to 1.15), particularly the T2D obesity (OR = 1.28; 95% CI = 1.15 to 1.42) and lipodystrophy (OR = 1.25; 95% CI = 1.03 to 1.51) clusters. No association was observed for T1D with PDAC risk (OR = 1.01; 95% CI = 0.99 to 1.02). Pathway/gene-set analysis using the summary-based Adaptive Rank Truncated Product (sARTP) method revealed a significant association between the MODY gene-sets and PDAC risk (P = 1.5 × 10−8), which remained after excluding 20 known PDAC GWAS loci (P = 7.6 × 10−4). HNF1A, FOXA3, and HNF4A were the top contributing genes after excluding the previously identified GWAS loci regions. Conclusions Our results from this genetic association study support that T2D, particularly the obesity and lipodystrophy mechanistic clusters, and MODY genomic susceptibility regions play a role in the etiology of PDAC.

Abstract Background Completing adjuvant chemotherapy and reducing toxicities are critical for maximizing survival after a colon cancer diagnosis. Sex, as a biological variable, may affect colon cancer chemotherapy completion, toxicities, and survival differently. Methods From a National Cancer Institute–sponsored trial conducted among patients with stage III colon cancer (Cancer and Leukemia Group B (Alliance)/Southwest Oncology Group 80702), we included 2201 patients receiving the standard adjuvant chemotherapy regimen of fluorouracil, leucovorin, and oxaliplatin. We calculated relative dose intensity to indicate chemotherapy completion and considered reduced relative dose intensity (values <85%) as a clinically significant deviation from standard fluorouracil, leucovorin, and oxaliplatin. Using National Cancer Institute’s Common Terminology Criteria for Adverse Events, we defined severe adverse events (grade ≥3) as the occurrence of any following event, including neutrophil count decrease, nausea, platelet count decrease, hypertension, peripheral neuropathy, diarrhea, fatigue, gastritis, creatinine level increase, gastric ulcer, myocardial ischemia, and cerebral ischemia. The primary survival outcome was disease-free survival (time from enrollment to colon cancer recurrence or death from any cause), and secondary survival outcomes were recurrence-free and overall survival. Results Compared with men, women were at statistically significantly higher risks of experiencing reduced relative dose intensity (adjusted odds ratio = 1.59, 95% CI = 1.29 to 1.96; P < .001) and severe advance events (adjusted odds ratio = 1.72, 95% CI = 1.41 to 2.11; P < .001). Yet, women had statistically significantly better disease-free survival (adjusted hazard ratio = 0.72, 95% CI = 0.59 to 0.87; P < .001) as well as better recurrence-free and overall survival. Conclusions Our findings suggested that women with colon cancer are more likely to have worse chemotherapy completion rates and more severe adverse events, but they have better survival. Sex as a biological variable warrants further consideration in chemotherapy administration and survivorship management after colon cancer diagnosis.

LBA3509 Background: Systemic inflammation has been implicated in colon cancer progression. We examined whether intake of a proinflammatory diet is associated with survival among patients (pts) with stage III colon cancer. Methods: This prospective cohort study was nested within a randomized phase III trial of adjuvant therapy in pts with stage III colon cancer who had undergone curative-intent resection. EDIP score – a validated tool to classify the inflammatory nature of diets – was derived as a cumulative exposure using data from food-frequency questionnaires completed within 6 weeks of randomization and 14-16 months (mo) after randomization. Cox proportional hazards regression was used to assess the associations of EDIP with disease-free survival (DFS) and overall survival (OS). Results: Of 1625 included pts, the mean (SD) age was 60.9 (10.5) years (yrs). Compared to pts in the lowest EDIP quintile, pts in the highest quintile (a more inflammatory diet) were younger (58.7 ± 10.8 vs 61.3 ± 9.5 yrs old) and more likely to be female (64.0% vs 48.9%) and have worse performance status (ECOG 1-2: 35.7% vs 19.4%). Pts in the highest quintile were less likely to be White (76.6% vs 92.0 %) and more likely to be Black (15.4% vs 3.7%). Baseline aspirin use, assigned chemotherapy (3 mo vs 6 mo), and assigned pharmacotherapy (celecoxib vs placebo) were not significantly different across EDIP quintiles. Compared with pts in the lowest EDIP quintile, pts in the highest quintile had significantly worse OS (multivariable hazard ratio [HR] 1.87, 95% confidence interval [CI] 1.26-2.77, P trend =0.01), but not DFS (HR 1.36, 95% CI 0.99-1.86, P trend =0.22). Diet and physical activity jointly influenced OS. Those with lower EDIP scores (quintiles 1-4, 80% of the study population) and higher physical activity (≥9 MET-h/wk) had the best OS (HR 0.37, 95% CI 0.25-0.53) compared with pts in the highest EDIP quintile (20% of the study population) and lower physical activity (<9 MET-h/wk) ( P interaction <0.001). The association between higher EDIP and OS was consistent when analyzed by celecoxib and placebo treatment arms ( P interaction 0.54). The relationship between EDIP and OS did not differ significantly according to aspirin use, with HR 1.60 (95% CI 0.71-3.60) among aspirin users and HR 2.01 (95% CI 1.27-3.16) among aspirin non-users ( P interaction 0.06). Conclusions: Our findings suggest that greater intake of a proinflammatory dietary pattern is associated with worse OS in pts with stage III colon cancer. Regular physical activity may attenuate the association, and further investigation of diet and physical activity intervention is warranted. Support: U10CA180821, U10CA180882, U24CA196171, U10CA180863, CCS 707213, UG1CA233234, U10CA180820, U10CA180868, U10CA180888; https://acknowledgments.alliancefound.org. Pfizer; ClinicalTrials.gov Identifier: NCT01150045.

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 .

Abstract Background A plant-based diet is associated with better survival among patients with nonmetastatic colorectal cancer (CRC), but its association in metastatic CRC is unknown. Methods Using an National Cancer Institute–sponsored trial (CALGB/SWOG 80405), we included 1284 patients who completed validated food frequency questionnaires at the initiation of metastatic CRC treatment. We calculated 3 indices: overall plant-based diet index (PDI), which emphasized consumption of all plant foods while reducing animal food intake; healthful plant-based diet index (hPDI), which emphasized consumption of healthful plant foods such as whole grains, fruits, and vegetables; and unhealthful plant-based diet index (uPDI), which emphasized consumption of less healthful plant foods such as fruit juices, refined grains, and sugar-sweetened beverages. We estimated the associations of 3 indices (quintiles) with overall survival (OS) and progression-free survival (PFS) using multivariable Cox proportional hazards regression. Results We observed 1100 deaths and 1204 progression events (median follow-up = 6.1 years). Compared with the lowest quintile, patients in the highest quintile of PDI had significantly better survival (hazard ratio [HR] for OS = 0.76 [0.62-0.94], Ptrend = .004; PFS = 0.81 [0.66-0.99], Ptrend = .09). Similar findings were observed for hPDI (HR for OS = 0.81 [0.65-1.01], Ptrend = .053; PFS = 0.80 [0.65-0.98], Ptrend = .04), whereas uPDI was not associated with worse survival (HR for OS = 1.16 [0.94-1.43], Ptrend = .21; PFS = 1.12 [0.92-1.36], Ptrend = .42). Conclusions Our study suggests that a plant-based diet, especially when rich in healthful plant foods, is associated with better survival among patients with metastatic CRC. The cause of survival benefits warrants further investigation.

3509 Background: HER2 overexpression/amplification (HER2+) occurs in ~3%-5% of pts with metastatic colorectal cancer (mCRC) and up to ~10% of pts with RAS/BRAF wild-type (WT) mCRC. The primary results of the MOUNTAINEER study (NCT03043313) demonstrated that the combination of tucatinib (TUC), a highly selective HER2-directed TKI, and trastuzumab (Tras) was well tolerated with clinically meaningful activity in pts with chemo-refractory HER2+ mCRC. Confirmed ORR was 38.1%, median DOR was 12.4 months, and median OS was 24.1 months. Here, we present results from the final analysis of MOUNTAINEER. Methods: MOUNTAINEER is a multi-center, open-label, randomized, phase 2 trial. Eligible pts had HER2+ and RAS WT mCRC with progression on or intolerance to last systemic therapy. Previous HER2-directed therapies were not permitted. The trial consisted of Cohort A, comprising pts treated with TUC (300 mg PO BID) + Tras (8 mg/kg IV then 6 mg/kg IV Q3W), as well as pts randomized 4:3 to receive TUC+Tras (Cohort B) or TUC monotherapy (Cohort C). Pts randomized to Cohort C were allowed to crossover and receive TUC+Tras on radiographic progression or if they did not achieve a complete or partial response by Week 12. Study endpoints evaluated at final analysis include DOR per BICR, PFS per BICR, OS, and safety. Results: The median duration of follow-up was 32.4 months (IQR, 25.1-46.7), with an additional 16.1 months of follow-up since the primary analysis (data cutoff, 02-Nov-2023). A total of 116 pts received at least 1 dose of study treatment (Cohorts A+B, N = 86; Cohort C, N = 30). In Cohorts A+B, median DOR per BICR was 15.2 months (95% CI, 8.9-20.5), median PFS per BICR was 8.1 months (95% CI, 4.2-10.2), and median OS was 23.9 months (95% CI, 18.7-28.3). In Cohort C post-crossover (N = 28), median DOR was not reached (95% CI, 2.8 months-NE). Median OS in Cohort C was 21.1 months (95% CI, 17.0-NE). The most common TEAEs in Cohorts A+B were diarrhea (66.3%), fatigue (44.2%), and nausea (34.9%). The majority of TEAEs were low grade, and rates were stable with longer follow-up. The most common grade ≥3 TEAE was hypertension (7.0%). TEAEs leading to TUC discontinuation in Cohorts A+B occurred in 5.8% of pts, which was unchanged from the primary analysis. In Cohort C, the most common TEAEs post-crossover were diarrhea (39.3%), back pain (21.4%), and pyrexia (21.4%); the most common grade ≥3 TEAE was AST increase (10.7%). No deaths resulted from TEAEs in any cohort and no new safety signals were identified. Conclusions: TUC+Tras continued to be well tolerated with sustained efficacy in pts with chemo-refractory RAS WT HER2+ mCRC, demonstrating clinically meaningful activity of the combination on longer follow-up. TUC+Tras is an important chemotherapy-free treatment option in HER2+ mCRC. TUC+Tras is being further evaluated in the first-line setting in combination with chemotherapy in the ongoing phase 3 MOUNTAINEER-03 trial (NCT05253651) for pts with HER2+ mCRC. Clinical trial information: NCT03043313 .