Citations

PURPOSETo determine the predictive and prognostic value of the consensus molecular subtypes (CMSs) of colorectal cancer (CRC) that represent a merging of gene expression–based features largely in primary tumors from six independent classification systems and provide a framework for capturing the intrinsic heterogeneity of CRC in patients enrolled in CALGB/SWOG 80405.PATIENTS AND METHODSCALGB/SWOG 80405 is a phase III trial that compared the addition of bevacizumab or cetuximab to infusional fluorouracil, leucovorin, and oxaliplatin or fluorouracil, leucovorin, and irinotecan as first-line treatment of advanced CRC. We characterized the CMS classification using a novel NanoString gene expression panel on primary CRCs from 581 patients enrolled in this study to assess the prognostic and predictive value of CMSs in these patients.RESULTSThe CMSs are highly prognostic for overall survival (OS; P < .001) and progression-free survival (PFS; P < .001). Furthermore, CMSs were predictive for both OS ( P for interaction < .001) and PFS ( P for interaction = .0032). In the CMS1 cohort, patients treated with bevacizumab had a significantly longer OS than those treated with cetuximab ( P < .001). In the CMS2 cohort, patients treated with cetuximab had a significantly longer OS than patients treated with bevacizumab ( P = .0046).CONCLUSIONThese findings highlight the possible clinical utility of CMSs and suggests that refinement of the CMS classification may provide a path toward identifying patients with metastatic CRC who are most likely to benefit from specific targeted therapy as part of the initial treatment.

PURPOSE CALGB/SWOG 80405 was a randomized phase III trial that found no statistically significant difference in overall survival (OS) in patients with first-line metastatic colorectal cancer treated with chemotherapy plus either bevacizumab or cetuximab. Primary tumor DNA from 843 patients has been used to discover genetic markers of OS. PATIENTS AND METHODS Gene mutations were determined by polymerase chain reaction. Microsatellite status was determined by genotyping of microsatellites. Tumor mutational burden (TMB) was determined by next-generation sequencing. Cox proportional hazard models were used, with adjusting factors. Interaction of molecular alterations with either the bevacizumab or the cetuximab arms was tested. RESULTS Patients with high TMB in their tumors had longer OS than did patients with low TMB (hazard ratio [HR], 0.73 [95% CI, 0.57 to 0.95]; P = .02). In patients with microsatellite instability–high (MSI-H) tumors, longer OS was observed in the bevacizumab arm than in the cetuximab arm (HR, 0.13 [95% CI, 0.06 to 0.30]; interaction P < .001 for interaction between microsatellite status and the two arms). Patients with BRAF mutant tumors had shorter OS than did patients with wild-type (WT) tumors (HR, 2.01 [95% CI, 1.49 to 2.71]; P < .001). Patients with extended RAS mutant tumors had shorter OS than did patients with WT tumors (HR, 1.52 [95% CI, 1.26 to 1.84]; P < .001). Patients with triple-negative tumors (WT for NRAS/ KRAS/ BRAF) had a median OS of 35.9 months (95% CI, 33.0 to 38.8 months) versus 22.2 months (95% CI, 19.6 to 24.4 months ) in patients with at least one mutated gene in their tumors ( P < .001). CONCLUSION In patients with metastatic colorectal cancer treated in first line, low TMB, and BRAF and RAS mutations are negative prognostic factors. Patients with MSI-H tumors benefited more from bevacizumab than from cetuximab, and studies to confirm this effect of MSI-H are warranted.

TPS679 Background: AA has re-emerged as a promising anti-cancer agent based on recent knowledge of pharmacokinetics, discovery of unexpected mechanisms of action, and early phase trials with IV AA.(Shenoy et al, Cancer Cell 34: 2018, in press) We hypothesized that ccRCC would be particularly susceptible to anti-cancer effects of IV AA due to: a. TET dependent demethylation of the hypermethylated genome of ccRCC causing re-expression of tumor suppressors (Shenoy et al, AACR 2018 Targeting DNA methylation conf. A11; Hu et al, Clin Cancer Res 20:4349-60, 2014) b. H2O2 production causing intra-tumoral oxidative damage, hypothesized to be enhanced by high iron content in RCC microenvironment c. Intracellular accumulation of dehydroascorbic acid secondary to high HIF activity in ccRCC. Animal data and case reports support the hypothesis. Methods: Trial design: Patients (pts) with newly diagnosed metastatic/ unresectable ccRCC are randomized 1:1 to arm A (pazopanib 800 mg/d plus IV AA 1g/kg 3 times/week) or arm B (pazopanib 800 mg/d). Protocol treatment is for 10 cycles (unless PD, unacceptable AE, alternative therapy, or pt refusal), each cycle being 28 days. Primary endpoint is Treatment Failure-Free rate at 40 weeks (TFF40). Treatment Failure is defined as: Radiographic disease progression, off-protocol treatment due to AE, alternative therapy initiation (except metastasectomy post clinical benefit), or death. Secondary endpoints include OS, PFS, ORR and AE. Statistical methods: 82 eligible pts (41 in each in arm) will provide 81% power to detect a 19% increase of TFF40 from 45% in arm B to 64% in arm A assuming a one-sided type I error rate of 0.19 (EAST 6.4). Correlatives: Epigenetic mechanism: 5mC, 5hmC and H3K27me3 IHC, MeDIP/ hMeDIP seq, RNA seq. H2O2 mechanism: tumor microenvironment iron, tumor catalase IHC. Dehydroascorbic acid mechanism: HIF-1 alpha, HIF-2 alpha, GLUT-1 IHC. Key exclusion criteria: G6PD deficiency, renal disease (Cockcroft Gault CrCl < 55 ml/min). ClinicalTrials.gov Identifier: NCT03334409 Status: Open for accrual in 9/10 planned sites. Funding Source: Foundation. Clinical trial information: NCT03334409.

Predicting the times of milestone events, ie, interim and final analyses in clinical trials, helps resource planning. This manuscript presents and compares several easily implemented methods for predicting when a milestone event is achieved. We show that it is beneficial to combine the predictions from different models to craft a better predictor through prediction synthesis. Furthermore, a Bayesian approach provides a better measure of the uncertainty involved in prediction of milestone events. We compare the methods through two simulations where the model has been correctly specified and where the models are a mixture of three incorrectly specified model classes. We then apply the methods on two real clinical trial data, North Central Cancer Treatment Group (NCCTG) N0147 and N9841. In summary, the Bayesian prediction synthesis methods automatically perform well even when the data collection is far from homogeneous. AnRshiny app is under development to carry out the prediction in a user‐friendly fashion.

588 Background: CALGB/SWOG 80405 found no difference in overall survival (OS) or progression-free survival (PFS) in 1137 patients with KRAS wild-type metastatic colorectal cancer (mCRC) treated with either the anti-VEGF agent bevacizumab (Bev) or the anti-EGFR agent cetuximab (Cet) in combination with chemotherapy (FOLFOX or FOLFIRI) as first-line therapy. Additional molecular biomarkers are required for the optimization of treatment choices for patients with mCRC. Methods: Levels of 24 proteins were assayed in EDTA-plasma samples using multiplex ELISA techniques. Plasma samples were collected at baseline and cycle 2 day 1 (C2D1). Analyses of baseline markers have been presented previously. Changes from baseline to C2D1 were expressed as an L-ratio (LR, log2 of C2D1 divided by baseline measure). LRs dichotomized at 0 were analyzed for potential prognostic and predictive effects on OS and PFS using Cox models while adjusting for confounders (post-hoc optimized cutpoints were used for PLGF, TIMP1, VCAM1, and VEGFR3 due to skew in the distributions of these markers). P-values are not corrected for multiple testing. Results: Baseline and matched C2D1 samples from 446 patients (212 Bev/234 Cet) were available for analysis. Thirteen markers were differentially modulated between arms (p < 0.05). Early increases in CD73 (p = 0.001), ICAM1 (p = 0.022), TIMP1 (p = 0.001), TSP2 (p = 0.024), and VEGFR3 (p = 0.006) were prognostic for shorter OS. Increases in ICAM1 (p = 0.008), TIMP1 (p = 0.042), and TGFB1 (p = 0.039) were prognostic for shorter PFS. Changes in VEGFR3 (pint = 0.097) and TGFBR3 (pint = 0.052) were predictive for OS and PFS, respectively. No other markers were predictive for OS or PFS (p < 0.1). Conclusions: Changes in circulating plasma protein biomarkers observed in patients enrolled in CALGB/SWOG 80405 were both prognostic and predictive for OS and PFS and warrant further study. Such changes could provide valuable information and help guide treatment decisions. Support: U10CA180821, U10CA180882, U10CA180888, U10CA180830; ClinicalTrials.gov: NCT00265850. [Table: see text]

Marine omega‐3 polyunsaturated fatty acids (MO3PUFAs) have anticancer properties and may improve colon cancer survival. However, it remains unknown whether the benefit differs by tumor molecular subtype. We examined data from a phase III randomized trial of FOLFOX or FOLFOX + cetuximab among 1,735 stage III colon cancer patients who completed a dietary questionnaire at enrollment. Multivariable hazard ratios and 95% confidence intervals (CIs) were calculated for the association between MO3PUFA and disease‐free survival (DFS) and overall survival according toKRASandBRAFV600Emutations and DNA mismatch repair (MMR) status. Higher MO3PUFA intake was associated with improved 3‐year DFS forKRASwild‐type tumors (77%vs. 73%; HR: 0.84; 95% CI: 0.67–1.05) but notKRAS‐mutant tumors (64%vs. 70%; HR: 1.30; 95% CI: 0.97–1.73;Pinteraction= 0.02). Similar heterogeneity was found by MMR (Pinteraction= 0.14): higher MO3PUFA was associated with better 3‐year DFS for tumors with deficient MMR (72%vs. 67%) but not proficient MMR (72%vs. 72%). No heterogeneity was found byBRAFV600Emutation. Similar findings were obtained for overall survival. In conclusion, we found a suggestive beneficial association between higher MO3PUFA intake and improved survival among stage III colon cancer patients with wild‐typeKRASand deficient MMR. Given the relatively small number of cases with tumor molecular assessments, further studies, preferably through pooled analyses of multiples cohorts, are needed to validate our findings.

612 Background: mCRC is a heterogeneous disease leading to possible disparate responses among lesions in a single pt. This study assesses the heterogeneity of lesion responses and evaluates the prognostic value of LBR12 and its mortality risk discrimination beyond RECIST responses. Methods: Pts with ≥ 2 lesions and no new lesions at 12 weeks (wks) were eligible. For each pt, after 12 wks of Rx, each lesion was categorized as progressive disease (L-PD: ≥20% increase in the longest diameter [LD]), partial response (L-PR: ≥30% decrease in LD), or stable disease (L-SD: neither L-PD nor L-PR). LBR12 was defined, per patient, by the combination of lesion responses: homogeneous LBR12 (L-PD, L-SD, L-PR only) and heterogeneous LBR12 (mixture of L-PD/L-SD, L-PD/L-PR, L-SD/L-PR). LBR12 and overall survival (OS) were correlated using stratified multivariate Cox models after adjusting for age, gender, and ECOG PS. Results: Among 9,092 mCRCs (Rx: chemo alone 44%; chemo + VEGF inhibitor [VEGFi] 42%; chemo + EGFR inhibitor [EGFRi] 10%) from 16 1st-line studies. Median OS: 2.2 years. Per RECIST at 12 wks, CR 0%; PR 36.1%; SD 60.9%; PD 3.0%. Responses in 52% were heterogeneous (Table). VEGFi and EGFRi treated pts had the highest rate of L-SD/L-PR (45%) and L-PR only (22%) status, respectively. Median OS increased monotonically across pts with more L-PRs and fewer L-PDs (Table). Pts with L-SD/L-PR status, among which 51% had SD per RECIST, had longer OS than those with L-SD only status (HRadj.= .81, padj.< .0001), but shorter OS than those with L-PR only status (HRadj.= 1.46, padj.< .0001). Pts with L-PD/L-SD status, among which 71% were SD per RECIST, had shorter OS than those with L-SD only status (HRadj.= 2.22, padj.< .0001). These associations were consistent across treatment regimens. Conclusions: The lesion-based response captures the heterogeneity of within pt lesion responses and provides refinement in predicting outcome beyond RECIST response at 12 wks. [Table: see text]

611 Background: Regorafenib is an oral multikinase inhibitor with survival benefit in refractory mCRC patients (pts). Toxicities such as Palmar-plantar erythrodysesthesia syndrome (PPES), fatigue and hypertension (HTN) have limited its use. Despite absence of supportive data, various dosing or interval scheduling have been implemented into clinical practice. Methods: A randomized phase II study of regorafenib dose-escalation (Arm A: 80 mg/day, weekly dose escalation if no significant drug-related toxicities, up to 160 mg/day) vs. standard dose (Arm B: 160 mg/day) in pts with mCRC for 21 days of a 28-day cycle. Pts were randomized 1:1:1:1 to arms A1 and B1 (Pre-emptive Clobetasol for PPES); A2 and B2 (Reactive Clobetasol). The primary endpoint was the proportion of patients who completed 2 cycles of treatment and initiated the 3rd in Arm A (Pooled A1 + A2) vs. Arm B (Pooled B1 + B2). Superiority for Arm A was to be declared if the one-sided p-value calculated using Fisher’s exact method was less than 0.2. Results: From June 2015 to June 2017, 123 pts were randomized with 116 (A = 54, B = 62) evaluable for the primary endpoint. Demographic data were well balanced with overall median age of 61yrs (range: 29-81), M/F (61/39%) and ECOG PS 0/1 (37/63%) and KRAS MT/WT/UNK (47/44/9%).The study met its primary endpoint with 43% of pts on Arm A initiating the 3rd vs. only 25% of pts Arm B [one-sided p-value 0.028]. Median Overall Survival (OS) was improved in Arm A vs. Arm B (9.0 mos vs. 5.9 mos; p = 0.094). Median Progression Free Survival (PFS) was 2.5 mos for Arm A vs. 2.0 mos for Arm B (p=0.553). Overall rates of grade 3/4 toxicity were more favorable for Arm A vs. Arm B (% PPES 15 vs. 16, HTN 7 vs. 15 and fatigue 13 vs. 18, respectively). Multiple QOL parameters were improved in A vs. B primarily at week 2 of the first cycle. Conclusion: A strategy with weekly dose escalation of regorafenib from 80 mg to 160 mg/day was found to be superior to a starting dose of 160 mg/day. These results establish a new standard for optimizing regorafenib dosing. Further data on outcomes of preemptive vs. reactive clobetasol strategies are undergoing analysis and will be presented later. Clinical trial information: NCT02368886.