Kuebler, J. Phillip

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 .

LBA14 Background: CALGB/SWOG 80702 previously showed that the addition of celecoxib to standard adjuvant chemotherapy with FOLFOX did not significantly improve disease-free survival (DFS) in patients with stage III colon cancer. Here, we evaluated the prognostic and predictive value of ctDNA in identifying a subpopulation of patients who may benefit from celecoxib. Methods: In the subset of patients with adequate biospecimens who participated in CALGB/SWOG 80702, a randomized phase III trial of 3 versus 6 months of adjuvant 5-FU, leucovorin, oxaliplatin (FOLFOX) +/- celecoxib, ctDNA assessment was performed using a clinically validated, tumor-informed 16-plex mPCR-NGS assay (Signatera(TM), Natera, Inc.) after surgery and before the start of adjuvant therapy (baseline). The Kaplan-Meier method was used to describe the distribution of survival time based on ctDNA positivity and log-rank testing was performed. Cox proportional hazards models were used to examine unadjusted associations between ctDNA positivity and disease-free (DFS) and overall survival (OS). Two-sided P values equal to or less than 0.05 were considered statistically significant, except for interaction P values (tested with a likelihood ratio). Results: In total, 1,011 of the 2,526 patients who participated in 80702 had ctDNA testing results from baseline; 189 were ctDNA positive (18.7%). ctDNA positivity associated with male sex, higher T stage, and N2 (versus N1) stage. ctDNA positivity was significantly associated with worse DFS (hazard ratio [HR] 6.52 [95% confident interval (CI) 5.09-8.34; p<0.0001] and OS (HR 6.28 [95% CI 4.63-8.51; p<0.0001]). Three-year DFS was 86.6% in ctDNA-negative cases and 36.8% in ctDNA-positive cases. Among patients who were ctDNA negative, celecoxib use was not significantly associated with worse DFS as compared to placebo (HR 0.75 [95% CI 0.54-1.05; p=0.095]) with a three-year DFS of 87.7% versus 85.5%, respectively. Among ctDNA-positive patients, celecoxib significantly improved DFS compared to placebo (HR 0.59 [95% CI 0.42-0.85; p=0.004]) with a three-year DFS of 44.1% versus 26.6% (P interaction = 0.25). Similar results were seen for overall survival with a hazard ratio of 0.86 (95% CI 0.56-1.33; p=0.49) for ctDNA negative cases and 0.63 (95% CI 0.41-0.96; p=0.028) for ctDNA-positive cases for celecoxib versus placebo (P interaction = 0.28). Conclusion: In a randomized phase III adjuvant therapy trial for stage III colon cancer, ctDNA was highly prognostic of DFS and OS. ctDNA positivity also appeared predictive of the benefit of adjuvant celecoxib for DFS and OS. These results suggest a potential role for ctDNA in determining which patients should consider celecoxib in addition to standard FOLFOX adjuvant therapy. Clinical trial information: NCT01150045 .

10 Background: In colon cancer, tumor deposits (TD) have been associated with worse prognosis, but they are included in the TNM staging system only in the absence of lymph node metastasis (i.e., stage III pN1c tumors). Here we aimed at evaluating the prognostic value of TD and the impact of the addition of TD in the count of lymph node metastases in patients with stage III colon cancer from the CALGB/SWOG 80702 phase III trial (NCT01150045). Methods: Pathological reports of all patients were reviewed for the presence and the count of TD, primary tumor sidedness, lymphovascular invasion and perineural invasion. Cases without available pathological report or without specific information of TD were excluded. Prognostic associations were evaluated by multi-variable Cox models adjusting for treatment arm, T-stage, N-stage, lymphovascular invasion, perineural invasion and lymph node ratio. Results: Overall, 2028 patients were included, with 524 (26%) TD-positive and 1504 (74%) TD-negative stage III tumors. Of the TD-positive patients, 80 (15.4%) were node negative (i.e., pN1c), 239 (46.1%) were pN1a/b and 200 (38.55%) were pN2. 17.2% and 37.0% of all pN1a/b and pN2 tumors had TD. Overall median follow-up was 69.3 months. The presence of TD was associated with poorer DFS (adjusted hazard ratio (aHR) = 1.59, 95%CI 1.28-1.91) and OS (aHR = 1.52, 95%CI 1.18-1.95) in the overall population. The negative effect of TD on DFS and OS was observed for both pN1a/b and pN2 groups and confirmed in multivariate Cox model. Among TD-positive patients, the number of TD had a linear negative effect on DFS and OS. Adding TD to the count of lymph node metastases, 104 of 1570 (6.6%) patients initially considered as pN1 were re-staged as pN2. Re-staged pN2 patients experienced worse DFS (3-year DFS rate: 65.5% versus 80.3%, P = .0003) and OS (5-year OS rate: 69.1 versus 87.8%, P = .0005) than patients confirmed as pN1. Re-staged pN2 patients had similar DFS than patients initially staged as pN2 (3-year DFS rate: 65.5% versus 63.1%, P = .1992). OS curves of these 2 groups crossed, with better outcomes during the first 3 years of follow-up but poorer 5-year estimates for re-staged pN2 patients (5-year OS rate: 69.1% versus 74.8%, P = .0436). Conclusions: TD are found in more than one fourth of stage III colon cancer specimens. The number of TD has a linear deleterious effect on patients’ prognosis. Adding the number of TD to the count of lymph node metastases improves the prognostication accuracy of the TNM staging. Support: U10CA180821, U10CA180882; https://acknowledgments.alliancefound.org . Clinical trial information: NCT01150045.

4003 Background: Aspirin and cyclooxygenase-2 (COX-2) inhibitors have been associated with a reduced risk of colorectal polyps and cancer in observational and randomized studies. CALGB/SWOG 80702 tested the effect of celecoxib, a COX-2 inhibitor, on reducing the risk of recurrence in stage III CC. Methods: CALGB/SWOG 80702 is a 2x2 randomized controlled phase III trial of 3 v 6 months of adjuvant FOLFOX (data previously reported as part of the IDEA collaboration) with concurrent celecoxib (400 mg daily) v placebo x 3 yrs for patients (pts) with resected stage III CC. The primary endpoint of the trial is disease-free survival (DFS), defined as time from randomization to recurrence or death from any cause. The trial was designed to provide 91% power to detect a hazard ratio (HR) of 0.79 in favor of celecoxib with 2-sided alpha = 0.05 (775 events required); due to slowing accumulation of events 4 years after complete accrual, power was lowered to 85% with same HR and alpha assumptions (696 events required). The DSMB released data on February 24, 2020 at median f/u of 5.6 yrs with 689 DFS events. Results: Between June 2010 and November 2015, 2,526 pts were consented and randomized to the trial. Treatment arms were well balanced by patient and tumor prognostic features, as well as low-dose aspirin use. Baseline characteristics included 45% female, 18% non-White, 8% Hispanic, 15% T4, 26% N2. 3-yr DFS for celecoxib was 76.3% v 73.3% for placebo (HR 0.89 [95% CI 0.77-1.04]; P = 0.14). 5-yr overall survival (OS) was 83.9% for celecoxib v 81.7% for placebo (HR 0.87 [95% CI 0.72-1.05]; P = 0.14). When considering the 4 treatment arms separately, 3-yr DFS was 77.0% for 12 months FOLFOX + celecoxib, 74.9% for 12 months FOLFOX + placebo, 75.5% for 6 months FOLFOX + celecoxib, and 71.9% for 6 months FOLFOX + placebo (log rank P = 0.22; P interaction = 0.64). There were no significant differences in grade 3-4 toxicity with celecoxib v placebo. Compliance with protocol celecoxib treatment, defined as 3 yrs of therapy completion or recurrence/death while on treatment, was 58.1% pts on celecoxib and 60.2% pts on placebo. Conclusions: The addition of celecoxib to standard chemotherapy did not significantly improve DFS or OS. Clinical trial information: NCT01150045 .

3640 Background: Prior economic analysis of a 12-gene assay (Oncotype DX), compared with patterns of care reported in the NCCN database of patients with stage II, T3, DNA mismatch repair proficient (MMR-P) colon cancer, predicted that the assay would save medical costs and improve patient well-being (Hornberger et al. Value Health 2012). This study assessed the validity of those findings with actual adjuvant chemotherapy (aCT) recommendations. Methods: Outcomes and costs were estimated for patients with stage II, T3, MMR-P colon cancer using a Markov model. A study of 141 patients from 17 sites in the Mayo Clinic Cancer Research Consortium collected data on aCT recommended before and after knowledge of the 12-gene assay results (Srivastava et al. abstract). Quality-adjusted life years (QALY) and medical resource use after recurrence were computed using guideline-validated state-transition probability estimation methods. Risk of progression and incidence of adverse events with different aCT regimens were based on published literature. Drug and administration costs for aCT were obtained from 2012 Medicare fee schedules. One-way sensitivity analyses were conducted to evaluate parameter influence on economic impact. Results: After receiving the 12-gene assay results, physician recommendations in favor of aCT decreased 22% (95% CI 11%-32%; McNemar test p<0.001) from 73 (52%) to 42 (30%) patients. Oxaliplatin aCT and 5-FU monotherapy recommendations each declined 11%. Average aCT costs decreased $3,228 for drugs, $750 for administration, and $3,168 for adverse events management. Overall, average total direct medical costs decreased $1,683. The net effect on average patient well-being was a gain of 0.102 QALYs. Total change in medical costs is most influenced by the cost of death due to colon cancer, time-preference discount rate, and the change in aCT recommendations. Savings are expected to persist even if the cost of oxaliplatin dropped by >75% due to generic substitution. Conclusions: The 12-gene assayhas been shown to alter aCT recommendations for patients with stage II, T3, MMR-P colon cancer. This study provides real-world confirmation that these aCT changes reduce direct medical costs and improve patient well-being.

453 Background: A 12-gene assay (Oncotype DX Colon Cancer) has been clinically validated as a predictor of recurrence risk in stage 2 colon cancer patients following surgery. We conducted the first prospective study to characterize the impact of Recurrence Score results on medical oncologists’ recommendations regarding adjuvant chemotherapy in T3, Mismatch Repair-proficient (MMR-P) stage 2 colon cancer patients. Methods: Consecutive patients with resected stage 2A colon cancer who were candidates for adjuvant chemotherapy were consented and enrolled by 105 medical oncologists from 17 sites in the Mayo Clinic Cancer Research Consortium. Each patient’s tumor specimen was assessed by the Recurrence Score test (quantitative RT-PCR) and MMR (IHC). Prior to and after receiving these results, physicians completed surveys indicating their planned treatments given hypothetical or known MMR results, recorded as Observation (Obs), 5FU-based chemotherapy (5FU), or 5FU + Oxaliplatin (Oxal). Change in treatment recommendation intensity from baseline to follow-up was defined as: increased if change from Obs to 5FU +/- Oxal or from 5FU to 5FU+Oxal, decreased if change from 5FU + Oxal to 5FU or Obs, or from 5FU to Obs, or no change. Results: 187 of 221 patients enrolled were evaluable including 141 who were MMR-P (avg age 63, 65% ECOG PS 0, med tumor size 5 cm, 11% high grade, 91% with 12+ nodes examined). In the primary analysis treatment recommendations changed for 63 (45%) of 141 MMR-P patients, with intensity decreasing for 47 (33%) and increasing for 16 (11%). Recommendations for chemotherapy (5-FU +/- Oxal) decreased from 73 (52%) patients pre-assay to 42 (30%) post-assay. Increased treatment intensity was more likely at higher Recurrence Score values and decreased intensity at lower Recurrence Score values (p=0.011), and any change was more likely when MMR status was unknown at baseline (p = 0.041). Conclusions: In this prospective study, quantitative recurrence risk information provided by the Recurrence Score test was associated with treatment recommendation changes for 45% of T3 MMR-P stage II colon cancer patients. Use of the 12-gene assay may lead to overall reductions in chemotherapy.

391 Background: Prior economic analysis of a 12-gene assay (Oncotype DX), compared with patterns of care reported in the NCCN database of patients with stage II, T3, DNA mismatch repair proficient (MMR-P) colon cancer, predicted that the assay would save medical costs and improve patient well-being (Hornberger et al., Value Health, 2012). This study assessed the validity of those findings with actual adjuvant chemotherapy (aCT) recommendations. Methods: Outcomes and costs were estimated for patients with stage II, T3, MMR-P colon cancer using a Markov model. A study of 141 patients from 17 sites in the Mayo Clinic Cancer Research Consortium collected data on aCT recommended before and after knowledge of the 12-gene assay results (Srivastava et al. abstract). Quality-adjusted life years (QALY) and medical resource use after recurrence were computed using guideline-validated state-transition probability estimation methods. Risk of progression and incidence of adverse events with different aCT regimens were based on published literature. Drug and administration costs for aCT were obtained from 2012 Medicare fee schedules. One-way sensitivity analyses were conducted to evaluate parameter influence on economic impact. Results: After receiving the 12-gene assay results, physician recommendations in favor of aCT decreased 22% (95% CI 11%-32%; McNemar test p<0.001) from 73 (52%) to 42 (30%) patients. Oxaliplatin aCT and 5-FU monotherapy recommendations each declined 11%. Average aCT costs decreased $5,738 for drugs, $668 for administration, and $3,268 for adverse events management. Overall, average total direct medical costs decreased $4,203. The net effect on average patient well-being was a gain of 0.083 QALYs. Total medical costs are most influenced by change in aCT recommendations, 5-FU monotherapy efficacy, and oxaliplatin drug acquisition cost. Savings are expected to persist even if the cost of oxaliplatin dropped by >75% due to generic substitution. Conclusions: The 12-gene assayhas been shown to alter aCT recommendations for patients with stage II, T3, MMR-P colon cancer. This study provides real-world confirmation that these changes in aCT reduce direct medical costs and improve patient well-being.