Ou, Fang‐Shu

TPS213 Background: Regorafenib (R) is an oral multikinase inhibitor that blocks several protein kinases involved in angiogenesis and oncogenesis; it has a survival benefit in refractory metastatic colorectal cancer (mCRC). The current standard (std) treatment in patients (pts) with RAS wildtype (WT) mCRC is sequential treatment with an anti-EGFR antibody (AEA) followed by R. However, R, which is orally administered once daily, may be more convenient and thus preferable for pts than AEA. REVERCE, a Japanese trial, demonstrated a significant 5.8 month (mo.) survival benefit with regorafenib administered prior to AEA compared to the std sequence. Based off these findings, the proposed phase II trial is to confirm the observed survival benefit from regorafenib sequencing prior to anti-EGFR monoclonal antibody therapy in REVERCE in a US patient population. Methods: REVERCEII is an Academic and Community Cancer Research United (ACCRU) network-led randomized phase II study of R (dose escalation from 80mg to 160mg based on tolerance) prior to AEA (R+AEA) compared to standard sequencing (AEA+R) in pts with refractory RAS WT mCRC. Patients are randomized 1:1 to receive R (Arm A) vs. AEA (with or without irinotecan per investigator choice) (Arm B). At the time of disease progression or intolerance, patients will receive sequential treatment until disease progression. Eligibility criteria include histologically confirmed mCRC, ECOG ≤ 2, acceptable organ function, and patients must have had prior fluoropyrimidine, oxaliplatin and irinotecan, and no prior AEA nor R. The primary objective is to compare the overall survival (OS), the primary endpoint, between evaluable patients (eligible, consented, started protocol treatment) who were randomized to R+AEA (arm A) and AEA+R (arm B). With 83 OS events, we have 87% power to detect an improvement in median OS from 9 months to 14.5 mo., assuming 1-sided significance level of 0.15, and exponential distribution. The total sample size is 124 patients. Secondary endpoints include progression-free survival, objective response, and adverse events. The total study duration is expected to be 3 years. Clinical trial information: NCT04117945. Clinical trial information: 04117945.

563 Background: RUB is an oral PARP1,2,3 inhibitor that demonstrated efficacy in patients (pts) with ovarian and prostate cancers harboring deleterious BRCA mutations. RUB exerts synergistic anti-tumor effect with IRI preclinically though the combination has overlapping toxicities. We previously published on the population PK of nal-IRI (Adiwijaya, Ma et al, Clin Pharm Ther 2017). We conducted a phase I study to evaluate a novel sequential dosing of RUB with nal-IRI/5FU in mGI cancer pts. Methods: Eligible pts had incurable mGI cancer previously received > 1 line of therapy (rx), ECOG PS 0-1, had RECIST measurable disease, adequate organ reserves and not received IRI for metastatic disease. Previous PARPi rx was excluded. The endpoints included dose limiting toxicity (DLT), maximum tolerated dose (MTD) and toxicity profile. The dose escalation utilized the 3+3 design. RUB was given oral bid on Day 4 to 13 and 18 to 27 with nal-IRI i.v. and 5FU i.v. 2400 mg/m2 over 46 hr on Day 1 and 15, every 28 day. Planned dose levels were RUB 400 mg/nal-IRI 50 mg/m2 (DL1), 400 mg/70 mg/m2 (DL2) and 600 mg/70 mg/m2 (DL3). Adverse events (AEs) were scored per CTCAE v4.03. Molecular profile was evaluated by CLIA-certified NGS testing. Results: Eighteen pts including 11 colorectal (CRC), 6 PANC, 1 gastroesophageal (GE) were enrolled and 12 were evaluable for DLTs. DL2 was not tolerable (DLT: G3 diarrhea, nausea and vomiting) and DL2A was added (RUB 600 mg/nal-IRI 50 mg/m2). DL2A enrolled 6 pts with no DLT and was determined as the MTD. Of DLT-evaluable pts, G3 and worse treatment-related AEs from all cycles were diarrhea (33%), fatigue (25%), leukopenia (25%), neutropenia (25%), anemia (8%) and nausea (8%). Four of 12 response evaluable pts had partial response: 2 CRC (1 had ATM mut), 1 PANC ( ATM mut), 1 GE ( BRCA2 mut) whilst 3 responders previously had platinum (PLA). Five pts had stable disease beyond 16 weeks (range 18.9 to 100.7 weeks), and all had prior PLA. Conclusions: The study successfully determined the MTD of RUB in combination with nal-IRI and 5FU. Encouraging efficacy was observed in PLA-treated mGI cancers including responses in those harboring ATM and BRCA alterations. The study is proceeding to evaluate the efficacy of the combination in metastatic pancreas cancer pts with and without BRCA1/2 or PALB2 alterations. Clinical trial information: NCT03337087.

193 Background: Enhanced understanding of the evolving clonal architecture under treatment stress is crucial to optimizing care and developing effective therapies in metastatic colorectal cancer (mCRC). Emergence of genomic alterations (GAs) [mutations (muts) and amplifications (amps)] in RAS, BRAF, EGFR, ERBB2, and MET have been recognized as key resistance mechanisms to anti-EGFR therapy in later lines in mCRC. Data regarding occurrence of these GAs under selective pressure in the first line setting is lacking. Methods: CALGB/SWOG 80405 was a randomized trial of bevacizumab (bev) vs cetuximab (cet) in first line mCRC. Patients (pts) with paired plasma samples (pre-treatment and post-progression) available for circulating tumor DNA (ctDNA) testing were included in this substudy. Sequencing of ctDNA was performed by Guardant360 assay in a CLIA-certified environment to detect GAs in 73 genes. RAS/BRAF status [mut vs. wild type (wt)] was based on clonal muts [pre-defined cutoff of relative MAF (rMAF) ≥ 25%] in ctDNA. Only samples with ≥1 GA were analyzed to minimize false negatives. The primary objective was to determine and compare prevalence of acquired GAs between study arms: bev (anti-VEGF) and cet (anti-EGFR). Descriptive statistics and Fisher’s exact test were used. Results: Baseline characteristics of ctDNA cohort were similar to the 80405 population. Among 133 randomized RAS/BRAF wt pts, 11 (15.3%) and 5 (8.2%) developed acquired GAs (OR 2.0, P = 0.29), in bev and cet arm, respectively. Key comparative data for pts with regard to acquired pathogenic GAs are shown in the table. Conclusions: In this randomized mCRC cohort, the ctDNA profile of acquired GAs with front line anti-EGFR chemotherapy appears to be strikingly distinct from that seen with later lines of therapy. Acquisition of GAs, classically associated with EGFR resistance in later line, was not only rare with upfront cet-chemotherapy but also comparable to bev-containing (anti-VEGF) regimen. The mechanisms of acquired resistance appear to differ when anti-EGFR therapy is administered in combination with highly active first line chemotherapy. Our findings have critical translational relevance to the timing and value of ctDNA-guided anti-EGFR rechallenge in mCRC pts, especially in those treated with anti-EGFR therapy upfront.[Table: see text]

116 Background: Constitutively activating KRAS or NRAS muts occur in ̃50% of CRC, increasing RAF-MEK-ERK signaling and causing overexpression of cyclin D1, which binds to cyclin dependent kinase 4/6 (CDK4/6) to drive cell cycle progression. Combination MEK and CDK4/6 inhibitors caused tumor regression in patient-derived xenografts of KRAS mut CRC. We hypothesized that binimetinib and palbociclib (B+P) would improve progression-free survival (PFS) compared to TAS-102 in refractory KRAS/NRAS mut mCRC. Methods: ACCRU-GI-1618 was a multicenter, randomized phase II clinical trial (NCT03981614). Key inclusion criteria were KRAS/NRAS mut mCRC, with prior fluoropyrimidine/ oxaliplatin/ irinotecan/ anti-VEGF therapy. There was a 6-patient safety run-in with binimetinib 30 mg po BID D1-28 and palbociclib 100 mg po daily D1-21. After, patients were randomized 1:1 to B+P vs TAS-102 (stratified by KRAS mut type and prior regorafenib use), with optional crossover at progression. The primary endpoint was PFS; 73 PFS events (from a sample size of 112) provided 90% power to detect improvement of PFS (hazard ratio = 0.5, i.e. median PFS of 2 vs. 4 months) with 1-sided α = 0.05. A prespecified interim analysis for futility was planned after 37 PFS events were observed, with completion of accrual if 1-sided stratified log-rank p-value < 0.551. Hazard ratios (HR) and 95% confidence intervals (CI) are estimated by stratified Cox proportional hazards models. Results: After the safety run-in, 93 patients at 6 sites were randomized; 82 (41 B+P, 41 TAS-102) comprise the primary analysis population (eligible, consented, and started treatment). In this population, median age was 52 years, 50% female, 68% left-sided, 79% with KRAS codon 12/13 mut, 12% with prior regorafenib. Enrollment was halted at interim analysis as the futility boundary was crossed (1-sided p = 0.67). At final analysis, 68 subjects had a PFS event (34 in each arm). Median PFS was 2.1 mo (95% CI 2.0-3.0) with B+P vs 2.1 mo (2.0-2.4) with TAS-102; HR 0.86 (0.52-1.44). 4-mo PFS rate was 22.2% (11.9-41.6) with B+P vs 10.6% (3.8-30.0) with TAS-102. With 37 OS events (14 in B+P arm), median OS was 7.7 mo (5.1-NE) with B+P vs 6.6 mo (4.8-8.9) with TAS-102; HR 0.77 (95% CI 0.39-1.51). TAS-102 had greater grade 3-4 hematologic AEs (46% vs 22%), and B+P had more grade 3-4 non-hematologic AEs (47% vs 32%). Grade 3-4 AEs more common with B+P were fatigue (8% vs 0%), oral mucositis (6% vs 0%), and nausea (4% vs 2%). Though 63% of patients on B+P had acneiform rash, only 2% was grade 3-4. Grade 1-2 diarrhea occurred in 35% of B+P and 24% of TAS-102 patients. No new safety signal was observed. Conclusions: B+P did not significantly improve median PFS or OS compared to TAS-102 in KRAS/NRAS mut mCRC. Subgroup analyses and translational studies are ongoing to determine which subgroups may be more likely to attain 4-mo PFS or identify mechanisms of resistance. Clinical trial information: NCT03981614.

92 Background: Since the publication of the MOSAIC trial, stage III CC has been treated with a six-month (mo) regimen of FOLFOX (fluorouracil, leucovorin, and oxaliplatin) or CAPOX (capecitabine and oxaliplatin). Recently, the IDEA collaboration challenged this practice by demonstrating that the 3-year rate of disease-free survival (DFS) was non-inferior to 6mo of treatment (Rx) when given for low risk CC (83.1 vs. 83.3%) and resulted in significantly lower rates of grade 2 and higher neuropathy. In high risk (T4, N2) patients (pts) the DFS of 3mo of CAPOX was equivocal to 6mo (64.1 vs. 64.0%), while 3mo of FOLFOX was inferior to 6mo (61.5 vs. 64.7%). We hypothesized that trends in prescribing would favor shorter courses of Rx with a preference towards CAPOX given its efficacy across both high and low risk CC. Methods: We performed a retrospective analysis of stage III CC pts from 4 institutions. We evaluated prescribing patterns of 3mo or 6mo of Rx and CAPOX vs. FOLFOX over a period of 5 years from Jan 2016 to Jan 2021, a time period that traverses before and after the release of IDEA. Logistic and multinomial logistic regression models, with a linear time trend, were used to estimate the percentage of pts receiving CAPOX vs. FOLFOX and the combination of Rx and duration, respectively, while adjusting for baseline characteristics. The prescribing patterns in important subgroups were examined by incorporating the interaction term in the models. Results: A total of 366 pts met inclusion criteria. From 2016-2021, there was a significant increase per quarter in patients treated with CAPOX when compared to FOLFOX (OR 1.16 95% CI 1.11 – 1.21, p <.001). Prior to IDEA, 78.3% of pts received 6mo FOLFOX and 7.4% received 3mo CAPOX. Two years after IDEA, only 17.3% of pts were on 6mo FOLFOX compared to 67.5% of pts on 3mo CAPOX (Table). At present, high risk pts are more likely to receive 6mo FOLFOX (47.8%) than 3mo of FOLFOX (3.9%), 3mo CAPOX (25.8%), or 6mo CAPOX (22.4%). Low risk pts are more likely to receive 3mo of CAPOX (67.9%) than other Rx. Conclusions: Our findings suggest that since IDEA, physician practice has significantly changed in favor of CAPOX and shorter courses of Rx. The use of CAPOX has significantly increased overall, presumably due to its efficacy across all risk groups and relatively reduced toxicity.[Table: see text]

Abstract Background Limited and conflicting findings have been reported regarding the association between social support and colorectal cancer (CRC) outcomes. We sought to assess the influences of marital status and living arrangement on survival outcomes among patients with stage III colon cancer. Patients and Methods We conducted a secondary analysis of 1082 patients with stage III colon cancer prospectively followed in the CALGB 89803 randomized adjuvant chemotherapy trial. Marital status and living arrangement were both self-reported at the time of enrollment as, respectively, married, divorced, separated, widowed, or never-married, and living alone, with a spouse or partner, with other family, in a nursing home, or other. Results Over a median follow-up of 7.6 years, divorced/separated/widowed patients experienced worse outcomes relative to those married regarding disease free-survival (DFS) (hazards ratio (HR), 1.44 (95% CI, 1.14-1.81); P =.002), recurrence-free survival (RFS) (HR, 1.35 (95% CI, 1.05-1.73); P = .02), and overall survival (OS) (HR, 1.40 (95% CI, 1.08-1.82); P =.01); outcomes were not significantly different for never-married patients. Compared to patients living with a spouse/partner, those living with other family experienced a DFS of 1.47 (95% CI, 1.02-2.11; P = .04), RFS of 1.34 (95% CI, 0.91-1.98; P = .14), and OS of 1.50 (95% CI, 1.00-2.25; P =.05); patients living alone did not experience significantly different outcomes. Conclusion Among patients with stage III colon cancer who received uniform treatment and follow-up within a nationwide randomized clinical trial, being divorced/separated/widowed and living with other family were significantly associated with greater colon cancer mortality. Interventions enhancing social support services may be clinically relevant for this patient population. Trial Registration ClinicalTrials.gov Identifier: NCT00003835

PURPOSECurrent tools in predicting survival outcomes for patients with colon cancer predominantly rely on clinical and pathologic characteristics, but increasing evidence suggests that diet and lifestyle habits are associated with patient outcomes and should be considered to enhance model accuracy.METHODSUsing an adjuvant chemotherapy trial for stage III colon cancer (CALGB 89803), we developed prediction models of disease-free survival (DFS) and overall survival by additionally incorporating self-reported nine diet and lifestyle factors. Both models were assessed by multivariable Cox proportional hazards regression and externally validated using another trial for stage III colon cancer (CALGB/SWOG 80702), and visual nomograms of prediction models were constructed accordingly. We also proposed three hypothetical scenarios for patients with (1) good-risk, (2) average-risk, and (3) poor-risk clinical and pathologic features, and estimated their predictive survival by considering clinical and pathologic features with or without adding self-reported diet and lifestyle factors.RESULTSAmong 1,024 patients (median age 60.0 years, 43.8% female), we observed 394 DFS events and 311 deaths after median follow-up of 7.3 years. Adding self-reported diet and lifestyle factors to clinical and pathologic characteristics meaningfully improved performance of prediction models (c-index from 0.64 [95% CI, 0.62 to 0.67] to 0.69 [95% CI, 0.67 to 0.72] for DFS, and from 0.67 [95% CI, 0.64 to 0.70] to 0.71 [95% CI, 0.69 to 0.75] for overall survival). External validation also indicated good performance of discrimination and calibration. Adding most self-reported favorable diet and lifestyle exposures to multivariate modeling improved 5-year DFS of all patients and by 6.3% for good-risk, 21.4% for average-risk, and 42.6% for poor-risk clinical and pathologic features.CONCLUSIONDiet and lifestyle factors further inform current recurrence and survival prediction models for patients with stage III colon cancer.

Abstract Background Combination irinotecan and cetuximab is approved for irinotecan-refractory metastatic colorectal cancer (mCRC). It is unknown if adding bevacizumab improves outcomes. Patients and Methods In this multicenter, randomized, double-blind, placebo-controlled phase II trial, patients with irinotecan-refractory RAS-wildtype mCRC and no prior anti-EGFR therapy were randomized to cetuximab 500 mg/m2, bevacizumab 5 mg/kg, and irinotecan 180 mg/m2 (or previously tolerated dose) (CBI) versus cetuximab, irinotecan, and placebo (CI) every 2 weeks until disease progression or intolerable toxicity. The primary endpoint was progression-free survival (PFS). Secondary endpoints included overall survival (OS), objective response rate (ORR), and adverse events (AEs). Results The study closed early after the accrual of 36 out of a planned 120 patients due to changes in funding. Nineteen patients were randomized to CBI and 17 to CI. Baseline characteristics were similar between arms. Median PFS was 9.7 versus 5.5 months for CBI and CI, respectively (1-sided log-rank P = .38; adjusted hazard ratio [HR] = 0.64; 95% confidence interval [CI], 0.25-1.66). Median OS was 19.7 versus 10.2 months for CBI and CI (1-sided log-rank P = .02; adjusted HR = 0.41; 95% CI, 0.15-1.09). ORR was 36.8% for CBI versus 11.8% for CI (P = .13). Grade 3 or higher AEs occurred in 47% of patients receiving CBI versus 35% for CI (P = .46). Conclusion In this prematurely discontinued trial, there was no significant difference in the primary endpoint of PFS between CBI and CI. There was a statistically significant improvement in OS in favor of CBI compared with CI. Further investigation of CBI for the treatment of irinotecan-refractory mCRC is warranted. Clinical Trial Registration: NCT02292758

Abstract Background The incidence of young-onset colorectal cancer (yoCRC) is increasing. It is unknown if there are survival differences between young and older patients with metastatic colorectal cancer (mCRC). Methods We studied the association of age with survival in 2326 mCRC patients enrolled in the Cancer and Leukemia Group B and SWOG 80405 trial, a multicenter, randomized trial of first-line chemotherapy plus biologics. The primary and secondary outcomes of this study were overall survival (OS) and progression-free survival (PFS), respectively, which were assessed by Kaplan-Meier method and compared among younger vs older patients with the log-rank test. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated based on Cox proportional hazards modeling, adjusting for known prognostic variables. All statistical tests were 2-sided. Results Of 2326 eligible subjects, 514 (22.1%) were younger than age 50 years at study entry (yoCRC cohort). The median age of yoCRC patients was 44.3 vs 62.5 years in patients aged 50 years and older. There was no statistically significant difference in OS between yoCRC vs older-onset patients (median = 27.07 vs 26.12 months; adjusted HR = 0.98, 95% CI = 0.88 to 1.10; P = .78). The median PFS was also similar in yoCRC vs older patients (10.87 vs 10.55 months) with an adjusted hazard ratio of 1.02 (95% CI = 0.92 to 1.13; P = .67). Patients younger than age 35 years had the shortest OS with median OS of 21.95 vs 26.12 months in older-onset patients with an adjusted hazard ratio of 1.08 (95% CI = 0.81 to 1.44; Ptrend = .93). Conclusion In this large study of mCRC patients, there were no statistically significant differences in survival between patients with yoCRC and CRC patients aged 50 years and older.