Goldberg, Richard M.

Importance The definition of cure in stage II to III colon cancer (CC) remains unclear due to limitations in conventional end points, which include deaths and second primary tumors as events. These can complicate communication with patients regarding long-term outcomes. Objective To distinguish relapses from competing health-related events to classify long-term outcomes years after surgery and explore when the incidence of true relapses of the initial CC approaches 0% to define cure in this disease. Design, Setting, and Participants This pooled analysis of individual patient–level data from 15 phase 3 randomized clinical trials assessed time to CC-related relapse using Kaplan-Meier and Aalen-Johansen methods, with death and second primary tumors treated as competing risks. Cox regression models evaluated prognostic associations, stratified by sex, stage, and tumor. Patients with stage II to III CC who underwent adjuvant chemotherapy were included. All patients had undergone radical surgery for CC and received adjuvant chemotherapy with a median follow-up of at least 6 years. The Adjuvant Colon Cancer Endpoints (ACCENT) and the International Duration Evaluation of Adjuvant Chemotherapy (IDEA) databases included adjuvant studies conducted between 1996 and 2015. Data were analyzed from February 2022 to June 2025. Exposures Adjuvant chemotherapy regimens varied across trials, including fluoropyrimidines alone or in combination with oxaliplatin or biologic agents. Main Outcomes and Measures The primary outcome was time to CC-related recurrence. The predefined threshold for cure was a recurrence risk below 0.5%. Results Of 35 213 included patients, 19 346 (54.9%) were male, and the mean (SD) age was 60.2 (10.8) years. The incidence rate of recurrence peaked at 6.4% (1993 of 31 373) between month 6 and month 12 and decreased continuously until year 10 of follow-up never exceeding 0.5%. Recurrence rate appeared to increase again after year 10 and peaked at 2.0% during year 12.5 to year 13, a pattern observed exclusively in the MOSAIC trial. Competing-event analysis revealed that death and second primary tumors inflated the apparent recurrence rate, especially for older patients. The overall cumulative incidence of relapse with death as competing risk was lower among female patients (hazard ratio, 0.58; 95% CI, 0.45-0.76; P < .001). Conclusions and Relevance In this pooled analysis of phase 3 randomized clinical trials, a recurrence rate less than 0.5% occurred after 6 years from surgery, supporting a practical definition of cure. Recognizing this milestone may improve patient communication, guide follow-up duration, and reduce unnecessary long-term surveillance.

Abstract Background Inflammation and insufficient physical inactivity contribute to individual-level risk of disease recurrence and death in stage III colon cancer. The extent to which increased inflammatory risk can be offset by sufficient physical activity remains unknown. Methods This cohort study was nested within the Cancer and Leukemia Group B (now part of the Alliance for Clinical Trials in Oncology) and Southwest Oncology Group randomized trial. Inflammatory burden was quantified by high-sensitivity C-reactive protein, interleukin-6, and soluble tumor necrosis factor-α receptor 2 after recovery from tumor resection. Physical activity was measured during and after postoperative chemotherapy. The primary endpoint was disease-free survival. Results The 3-year disease-free survival rate was 88.4% among patients with low inflammation and sufficient physical activity (referent group for all comparisons), 84.9% with low inflammation and insufficient physical activity (absolute risk difference = −3.5 percentage points, 95% confidence interval [CI] = −11.3 to 4.3; P = .38), 78.0% with intermediate inflammation and insufficient physical activity (absolute risk difference = −10.4 percentage points, 95% CI = −17.4 to −3.3; P = .007), and 79.7% with high inflammation and insufficient physical activity (absolute risk difference = −8.7 percentage points, 95% CI = −15.7 to −1.6; P = .022). In contrast, the 3-year disease-free survival rate was 87.3% among patients with intermediate inflammation and sufficient physical activity (absolute risk difference = −1.1 percentage points, 95% CI = −7.5 to 5.3; P = .74) and 84.4% with high inflammation and sufficient physical activity (absolute risk difference = −4.0 percentage points, 95% CI = −12.3 to 4.3; P = .34). Conclusion In this observational study of stage III colon cancer patients, physical activity was associated with improved disease-free survival despite high inflammation. Patients with intermediate or high inflammation who were physically active had disease-free survival rates that were not statistically significantly different from those with low inflammation.

60 Background: DDR mutations are associated with higher neoantigen load and tumor infiltrating lymphocytes, and are a potential biomarker for immunotherapy. We investigated the association of DDR mutations in gastric (GC), esophageal (EC), and gastroesophageal junction (GEJ) cancers with MSI, PD-L1, and TMB, known predictors for immune checkpoint inhibitors. Methods: 20 DDR mutations were tested by Next-Generation Sequencing (NGS) with a 592-gene panel on a total of 1935 (709 EC; 831 GC; 355 GEJ) cancers. TMB was assessed by NGS, MSI by NGS or fragment analysis, and PD-L1 by IHC (22c3 for CPS or SP142). Results: GC had the highest DDR mutation rate compared to EC and GEJ (27% vs. 20%, p = 0.0005 and 17%, p = 0.0002, respectively). MSI-High (MSI-H) was significantly more common in the DDR mutated cohort (DDR-M) compared to non-mutated cancers (18% vs. 1%; p < 0.0001). TMB-High (≥ 10 mutations/megabase [mt/MB]) was higher in DDR-M (35% vs. 21%; p < 0.0001); in DDR-M cohort, GC had the highest TMB compared to DDR-M EC and GEJ (mean: 13.8 vs. 9.4 vs. 10 mt/MB, respectively; p < 0.0001). DDR mutations were more frequent in the PD-L1 combined positive score (CPS) ≥ 50 group than CPS 0 (42.9% vs. 24%; p = 0.037) and CPS 1-9 (42.9% vs. 20.6%; p = 0.005). ARID1A, ATRX, BRCA2, and PTEN were the most prevalent DDR mutations in MSI-H (87%, 31%, 25%, 24%, respectively); ARID1A, ATRX, BRCA2, and PTEN in TMB-High (47%, 7.7%, 6.7%, 6.8%) and ARID1A, BRCA2, RAD50, and WRN in PD-L1 high (CPS ≥ 10) (48.5% vs. 5.2% vs. 2.5% vs. 3.4%). Conclusions: MSI-H, TMB-high and high PD-L1 expression were significantly more prevalent in the DDR-M cohort compared to non-DDR-mutated cancers, most pronounced in GC. Alterations in ARID1A, ATRX, BRCA2, and PTEN were correlated with MSI-H and TMB-high while ARID1A, BRCA2, RAD50, and WRN were correlated with increased PD-L1 expression. Our findings may help identify patients for tailored immunotherapy approaches in future clinical trials.

505 Background: MSI is a tumor biomarker for immunotherapy efficacy that is closely associated w/deficient MMR, and is also variably associated w/somatic muts of the MMR genes, loss of MMR protein expression by immunohistochemistry (IHC), and high TMB. Germ-line muts (Lynch syndrome/LS) in the 4 MMR genes are recognized to have distinct cancer spectrums/penetrance in LS, yet across all tumors, gene-specific variability in MMR IHC, MMR muts, and TMB is understudied. Methods: Results of TGPs performed by Caris Lifesciences (2015-17) were analyzed in colorectal (CRC), endometrial (EC) and all other cancers/tumors (OT) as: 1) all MSI-H tumors (n = 1057) and 2) all tumors w/ ≥1 mut in an MMR gene (n = 470). A subset of cases had IHC for MMR protein and PD-L1 expression. MSI and TMB were determined by NGS. Results: Characteristics of MSI-H tumors and tumors w/ ≥1 MMR mut are seen in the Table. A single MSH6 mut [F1088fs] in a coding microsatellite represented 31% of all MMR muts detected. F1088fs was found in 58% tumors w/MLH1/PMS2 loss (IHC) but only 25% w/MSH2/MSH6 loss (p < 0.001), was more commonly seen in EC vs CRC/OT (p < 0.001), and was negatively associated w/somatic POLE mut (p = 0.002). Distinct mut signatures in the MMR genes (e.g. GLUàSTOP) were seen in tumors w/POLE muts and DNA repair genes. Conclusions: MSI-H and MMR mutated tumors demonstrate marked gene-specific heterogeneity in IHC patterns, TMBs, and somatic muts that may be relevant to treatment selection, resistance, and response. [Table: see text]

614 Background: A consensus interpretation of the IDEA colon cancer study results suggested that risk categories based on T/N stage grouping be used to guide decision-making for duration (3 vs 6 months) of adjuvant FOLFOX or CapeOX chemotherapy. Given the prognostic potential of immune biomarkers, we examined the immunoscore and individual T and B lymphocyte markers in low and high risk T/N subsets of stage III colon carcinoma patients (N=600) treated with adjuvant FOLFOX. Methods: Immunoscore (CD3+, CD8+) and individual T-cell and CD20+ B-cell immunostain densities in central tumor (CT) and invasive margin (IM) of FFPE sections were quantified by image analysis. A predetermined immunoscore categorization was used [high (2-4) vs low (0-1)]. Individual markers were analyzed by backwards selection wherein CD3+ IM was most robust for prognosis and an optimized cutoff was then determined. Associations with disease-free survival (DFS) were analyzed by multivariable Cox regression adjusting for age, T/N stage, sidedness, KRAS/BRAF, and DNA mismatch repair. Results: In low and high risk T/N patient subsets, the immunoscore and CD3+ IM were each significantly discriminant for prognosis. Among low risk (T1-3N1) patients, a high vs low immunoscore was associated with a 91% vs 77% 3-year DFS [HR 0.57, 95% confidence interval (CI) 0.34-0.95, adjusted (adj) P= 0.026]. Among high risk (T4 or N2) patients, a high vs low immunoscore was associated with a 68% vs 54% 3-year DFS (HR 0.64, 95% CI 0.42-0.98, Padj= 0.034]. Similarly, a high vs low intratumoral CD3+ density at the invasive margin (IM) was significantly associated with prognosis in low risk [HR 0.37, 95% CI 0.21- 0.66), Padj< 0.0003] and in high risk [HR 0.47, 95% CI, 0.27- 0.80), Padj< 0.0028] patient subsets. Conclusions: Immunoscore and CD3+ IM were shown to prognostically stratify FOLFOX-treated patients within both low and high risk T/N subsets. These data underscore limitations of the T/N risk classification for adjuvant treatment decisions in stage III patients, and demonstrate the ability of T-cell markers to enhance prognostication to guide clinical decision-making.

3579 Background: Tumor infiltrating lymphocytes (TIL) indicate a host immune response that may influence survival. Immunoscore was developed using CD3+ and CD8+density and location in primary CC pts with pooled stages, varying treatment and follow-up. We determined if individual immune markers and/or Immunoscore are prognostic in resected stage III CC pts (N=600). Methods: CD3+ and CD8+ T-cell or CD20+ B lymphocyte density in central tumor (CT) and invasive margin (IM) was evaluated by immunostaining and quantified by image analysis. Immunoscore was calculated on a scale of I0 to I4 with high densities of CD3+ and CD8+in both CT and IM scored as I4; low densities scored as I0. Associations with disease-free survival (DFS) were evaluated by multivariable Cox regression adjusting for covariates. Results: Data for CD3+, CD8+ and CD20+ were generated (N=595). Higher density of CD3+ CT, CD3+ IM and CD8+ IM were associated with longer DFS adjusting for covariates (Table). CD3+ IM had the strongest association with DFS, and was stronger in left-sided (HRadj.=0.81, 95% CI, 0.70-0.94, padj.= 0.0049) vs right-sided (HRadj.=0.93, 95% CI, 0.85-1.0 padj.=0.52) tumors (pinteraction=0.039). Higher density of CD3+ IM was associated with older age (p=0.034), T1/2 (p<.0001), N1 (p=0.017), right-sided (p=0.013), high TILs (p=0.0008), and deficient MMR (p=0.0003). Using a prior Immunoscore risk stratification, higher scores were associated with better DFS (HR.=0.62, CI, 0.44-0.87, p=0.006) (Table). Conclusions: Densities of CD3+ and CD8+, especially at IM, are individually prognostic in FOLFOX-treated pts. Association of CD3+IM with prognosis differed by primary CC site. Immunoscore was strongly prognostic, and this result provides validation in a clinical trial cohort. [Table: see text]

Abstract Purpose: To determine the frequency and prognostic association of molecular markers by anatomic tumor site in patients with stage III colon carcinomas. Experimental Design: In a randomized trial of adjuvant FOLFOX ± cetuximab, BRAFV600E and KRAS (exon 2) mutations and DNA mismatch repair (MMR) proteins were analyzed in tumors (N = 3,018) in relationship to tumor location, including subsite. Cox models were used to assess clinical outcome, including overall survival (OS). Results: KRAS codon 12 mutations were most frequent at the splenic flexure and cecum; codon 13 mutations were evenly distributed. BRAF mutation frequency sharply increased from transverse colon to cecum in parallel with deficient (d) MMR. Nonmutated BRAF and KRAS tumors progressively decreased from sigmoid to transverse (all P &lt; 0.0001). Significantly, poorer OS was found for mutant KRAS in distal [HR, 1.98; 95% confidence interval (CI), 1.49–2.63; P &lt; 0.0001] versus proximal (1.25; 95% CI, 0.97–1.60; P = 0.079) cancers. BRAF status and outcome were not significantly associated with tumor site. Proximal versus distal dMMR tumors had significantly better outcome. An interaction test was significant for tumor site by KRAS (Padjusted = 0.043) and MMR (Padjusted = 0.010) for OS. Significant prognostic differences for biomarkers by tumor site were maintained in the FOLFOX arm. Tumor site was independently prognostic with a stepwise improvement from cecum to sigmoid (OS: Padjusted = 0.001). Conclusions: Mutation in BRAF or KRAS codon 12 was enriched in proximal cancers whereas nonmutated BRAF/KRAS was increased in distal tumors. Significant differences in outcome for KRAS mutations and dMMR were found by tumor site, indicating that their interpretation should occur in the context of tumor location. Clin Cancer Res; 21(23); 5294–304. ©2015 AACR.