Cutsem, Eric Van

Abstract Background Synthetic control arms (SCAs) derived from historical trial data can complement randomized controlled trials (RCTs), particularly in oncology where feasibility, ethical, and cost constraints may limit conventional trial designs. However, their validity for overall survival (OS) remains uncertain. We evaluated the feasibility and limitations of constructing SCAs from the ARCAD metastatic colorectal cancer (mCRC) database across multiple treatment lines. Methods Seven landmark RCTs representing first-, second-, and third-line settings were selected. External control arms were constructed from ARCAD individual patient-level data using propensity score matching based on key clinical and biological variables from a validated ARCAD prognostic score, with adjustment for geographic region and time era when needed. A prespecified two-step benchmarking framework assessed: (1) control-arm OS reproducibility and (2) virtual trial comparisons between matched synthetic controls and original RCT experimental arms. Agreement was evaluated using hazard ratios (HRs) and Z-tests. Results A total of 28,022 patients met the inclusion criteria. ARCAD-derived SCAs were successfully constructed for all selected RCTs and closely reproduced control-arm OS. After matching, baseline characteristics were well balanced, with minimal differences between included and excluded patients. Virtual trials showed concordant treatment-effect estimates with the original RCTs, with a median absolute HR deviation of 0.05 and no significant differences by Z-tests (P>.05). Survival outcomes were consistently reproduced across treatment lines. Conclusion ARCAD-derived SCAs reliably reproduced control-arm OS and benchmark treatment-effect estimates from landmark RCTs in mCRC. Despite limitations related to residual confounding and missing data, this framework supports benchmarking, trial design, and exploratory analyses when conventional control arms are impractical.

Abstract Purpose Traditional adverse event (AE) reporting in oncology trials focuses on the single worst CTCAE grade, which may underrepresent chronic or recurrent toxicity burden. We applied a longitudinal toxicity framework to compare toxicity profiles of chemotherapy with or without cetuximab in metastatic colorectal cancer. Patients and Methods We pooled two randomized first-line trials in the ARCAD database. AEs examined were diarrhea, rash, hand-foot syndrome (HFS), fatigue, anorexia, and mucositis. Outcomes included grade ≥3 AE, time to first occurrence of maximum grade, early onset (≤6 weeks), and AEL, a normalized measure of cumulative toxicity burden over treatment. Analyses were adjusted for chemotherapy backbone, ECOG performance status, sex, primary tumor location, dose reduction, and treatment duration. Results Compared with Chemotherapy alone (n = 564), Chemotherapy plus cetuximab (n = 738) was associated with higher grade ≥3 rash (21% vs 0.5%; adjusted odds ratio [OR] 49.89, 95% CI 15.8–157.4), higher rash AEL (0.257 vs 0.069; adjusted mean difference 0.22, 95% CI 0.21–0.23), and more frequent early-onset maximum rash (67% vs 34%; adjusted OR 4.28, 95% CI 2.72–6.74). Rash AEL remained higher with cetuximab within maximum-grade strata. HFS showed higher grade ≥3 risk and overall AEL with cetuximab, but no within-grade AEL difference, indicating higher overall HFS burden reflected grade distribution rather than within-grade chronicity. No consistent differences were observed for other AEs. Conclusions Incorporating onset timing and AEL distinguished persistent toxicity burden from isolated peak events. This framework may support comparative tolerability assessment when chronic toxicity burden is central to decision-making.

707 Background: Due to insufficient data, therapy for unresectable, locally advanced pancreatic adenocarcinoma (LAPAC) is based on trials in metastatic disease, and outcomes remain poor. TTFields disrupt cancer cell division using alternating low-frequency electric fields delivered externally by a portable device. In the phase 3 PANOVA-3 trial (NCT03377491), TTFields with gemcitabine/nab-paclitaxel (GnP) significantly improved overall survival (OS; HR 0.82) and pain-free survival (HR 0.74) vs GnP in patients with unresectable LAPAC. Methods: In PANOVA-3, patients with newly diagnosed LAPAC were randomized 1:1 to receive GnP with or without concomitant TTFields. Kaplan-Meier methodology was used for time-to-event analyses. Response evaluations were based on RECIST V1.1. OS, pain-free survival, and safety were analyzed post-hoc in subgroups based on sex (male, female), age ( < 65, ≥65 years), and BMI (<25, ≥25 kg/m 2 for efficacy; ≤20, 20–25, 25–30, ≥30 kg/m 2 for safety). Differences between treatment arms were compared using the log-rank test. Results: Efficacy outcomes are shown in the table. TTFields significantly extended pain-free survival in females and patients ≥65 years. Device-related adverse events (AEs) were comparable between sexes, older and younger patients, and across BMI ranges. Some device-related skin adverse events occurred more frequently in females (e.g. dermatitis, 33.1% vs 22.7%; rash 21.8% vs 13.5%, females vs males, respectively); others occurred more often in males (e.g. maculo-papular rash, 9.8% vs 14.2%; erythema, 9% vs 12.1%, females vs males, respectively). Dermatitis and pruritus had a higher incidence in the BMI ≥30 kg/m 2 subgroup (38.5%), whereas patients with BMI <30 kg/m 2 did not show noticeable differences in device-related AEs. Skin irritation (11.5% vs 5.5%) and skin reactions (8.5% vs 2.8%) were more common in patients ≥65 years than patients <65 years. Conclusions: Median OS and pain-free survival in these post-hoc subgroup analyses are generally consistent with the overall analysis, supporting use of TTFields with GnP in unresectable LAPAC. No new safety concerns were noted; observations were consistent with the general PANOVA-3 population. Clinical trial information: NCT03377491 . Survival outcomes for the subgroup analyses. Median OS, months TTFields + GnP GnP P value Age<65 years≥65 years 18.6 (n=113)15.4 (n=172) 16.0 (n=114)12.9 (n=172) 0.2060.061 SexFemaleMale 16.8 (n=138)15.7 (n=147) 14.5 (n=161)13.4 (n=125) 0.1140.145 BMI<25≥25 16.7 (n=166)16.2 (n=117) 14.2 (n=174)14.5 (n=108) 0.1550.105 Median pain-free survival, months Age<65 years≥65 years 16.5 (n=113)13.1 (n=172) 9.2 (n=114)8.3 (n=172) 0.4070.035 SexFemaleMale 16.5 (n=138)15.2 (n=147) 8.3 (n=161)9.3 (n=125) 0.0260.478 BMI<25≥25 16.6 (n=166)14.7 (n=117) 9.1 (n=174)8.3 (n=108) 0.1170.088

Abstract Purpose: Routine testing for mismatch repair deficiency (dMMR)/microsatellite instability (MSI) in colorectal cancers is recommended for Lynch syndrome screening, prognosis, and treatment guidance. In the metastatic setting, RAS/BRAF mutations guide treatment decisions. The impact of these mutations on the tumor immune microenvironment (TiME) in MSI/dMMR colorectal cancer is not known. Experimental Design: The study involved retrospective analysis of 448 patients with stage I to IV MSI/dMMR colorectal cancer profiled using next-generation sequencing (Tempus xT DNA sequencing of 595–648 genes at 500x coverage and Tempus xR whole-exome capture RNA sequencing). MSI status was determined by assessing 44 or 239 loci using next-generation sequencing. dMMR was determined using IHC. Tumor mutational burden, tumor neoantigen burden (NTB), PD-L1, immune infiltration, and canonical immune pathways (76 gene set signatures) were analyzed. Results: The median age at diagnosis was 67 years (range, 21–86); 59% of patients were female, and 70% were stage III to IV. Among the 448 patients, 100 (22%) harbored RAS mutations (RASmut), 119 (27%) a BRAFV600E mutation, and 229 (51%) were double wild type. RASmut exhibited lower NTB (median, 12 vs. 15 vs. 16; P = 0.003) and PD-L1 (3.6% vs. 13% vs. 24%; P &lt; 0.001) than BRAFV600E and wild-type tumors, respectively. The RASmut TiME had lower overall inflammation and fewer infiltrating CD8+ T cells than wild-type or BRAFV600E tumors. In contrast, BRAFV600E tumors exhibited hyperproliferative characteristics associated with broad metabolic reprogramming but a similarly inflamed TiME compared with wild-type tumors. Conclusions: Our data suggest that MSI/dMMR colorectal cancers harboring RASmut are less immunogenic, and the TiME contains a lower inflammatory profile than wild-type or BRAFV600E tumors. Further analysis and validation are required to confirm these findings.

PURPOSE Colorectal cancer (CRC) incidence and mortality have decreased since the 1970s, but the incidence in young adults (<50 years, named early-onset CRC [eoCRC]) has been increasing. PATIENTS AND METHODS Individual patient data on 13,365 patients with metastatic CRC enrolled between 2000 and 2012 in 17 first-line randomized trials in the Aide et Recherche en Cancérologie Digestive database were pooled. The distribution of demographics, clinicopathologic features, biomarkers, and outcome data were summarized and compared by age groups. Progression-free survival (PFS) and overall survival (OS) were assessed by Kaplan-Meier curves and Cox models stratified by treatment arms within studies, adjusting for potential confounders. Predictive value of age group on clinical outcomes was evaluated by testing interaction effect between treatment and age variables. RESULTS Overall, 2,045 patients with eoCRC (median age, 42.5) and 11,320 patients with average-onset CRC (aoCRC; median age, 63.8) were included in this analysis. Within the eoCRC population, treatment with bevacizumab in addition to chemotherapy improved PFS (9.9 v 6.8 months; hazard ratio [HR], 0.66 [95% CI, 0.54 to 0.80]; P < .0001), which was similar to the findings in aoCRC population (9.4 v 7.3 months; HR, 0.73 [95% CI, 0.67 to 0.80]; P < .001; interaction P = .5415). However, epithelial growth factor receptor inhibitor (EGFRi) did not improve PFS in RAS wild-type (WT) patients with eoCRC who had left-sided primary tumors (8.3 v 8.9 months; HR, 1.20 [95% CI, 0.81 to 1.77]; P = .36), whereas EGFRi significantly improved PFS in the aoCRC population (9.9 v 8.5 months; HR, 0.74 [95% CI, 0.64 to 0.86]; P < .0001; interaction P = .083). CONCLUSION Treatment-naïve patients with metastatic eoCRC appear to derive similar benefit from bevacizumab as patients with aoCRC. However, patients with eoCRC with left-sided RAS/RAF WT tumors did not appear to derive benefit from first-line EGFRi.

LBA4005 Background: To date, no phase 3 clinical trial has demonstrated an overall survival (OS) benefit in patients with locally advanced pancreatic adenocarcinoma (LA-PAC). TTFields are electric fields that disrupt cancer cell division. TTFields therapy is approved for glioblastoma, pleural mesothelioma, and metastatic non-small cell lung cancer. A phase 2 trial in PAC demonstrated the safety and preliminary efficacy of TTFields therapy with gemcitabine with or without nab-paclitaxel. We report final data from PANOVA-3 (NCT03377491), the largest global, phase 3, randomized, open-label trial in LA-PAC to date. Methods: Adult patients with newly diagnosed unresectable LA-PAC were randomized 1:1 to receive TTFields therapy (150 kHz) with gemcitabine/nab-paclitaxel (GnP) or GnP. The primary endpoint was OS. Secondary endpoints included progression-free survival (PFS), local PFS, objective response rate (ORR), and pain-free survival. Distant PFS (metastases beyond the pancreas and regional lymph nodes) was assessed post hoc. Survival data were compared using the Kaplan-Meier method and a log-rank test. Results: 571 patients were randomized. Baseline characteristics were generally well balanced between the study arms. OS was significantly longer with TTFields/GnP than with GnP (median 16.2 [95% CI: 15.0, 18.0] vs 14.2 months [95% CI: 12.8, 15.4]; HR 0.82 [95% CI: 0.68, 0.99], p=0.039). One-year survival rate was also significantly improved with TTFields/GnP vs GnP (68.1% [95% CI: 62.0-73.5] vs 60.2% [95% CI: 54.2-65.7], p=0.029). There was no significant difference in PFS or local PFS between arms. Pain-free survival was significantly longer with TTFields/GnP vs GnP (median 15.2 [95% CI: 10.3, 22.8] vs 9.1 months [95% CI: 7.4, 12.7]; HR 0.74 [95% CI: 0.56, 0.97], p=0.027). Post-hoc analysis showed significant distant PFS benefit (median 13.9 [95% CI: 12.2, 16.8] vs 11.5 months [95% CI: 10.4, 12.9], HR 0.74 [95% CI: 0.57, 0.96], p=0.022) with TTFields/GnP vs GnP. ORR was similar between arms (36.1% [95% CI: 30.0, 42.4] vs 30.0% [95% CI: 24.3, 36.2], p=0.094). 97.8% and 98.9% of patients who received TTFields/GnP and GnP, respectively, had adverse events (AEs) and 88.6% and 84.3% had grade ≥3 AEs. The most frequent grade ≥3 AEs were neutropenia (47.8% and 47.6%) and anemia (21.9% and 22.3). 81% of patients receiving TTFields/GnP had device-related AEs, mostly grade 1/2 skin AEs, e.g., dermatitis (27.7%), rash (17.5%), and pruritus (15.0%); grade 3 and grade 4 device-related AEs occurred in 9.1% and 0.4% of patients, respectively. Conclusions: PANOVA-3 is the largest phase 3 trial exclusively performed in patients with LA-PAC and the first to show a statistically significant OS benefit. With no additive systemic toxicity and a statistically significant pain-free survival benefit, TTFields therapy is a potential new standard treatment for LA-PAC. Clinical trial information: NCT03377491 .

LBA3500 Background: BREAKWATER (NCT04607421) is an open-label, global, randomized, phase 3 study evaluating first-line (1L) encorafenib + cetuximab (EC) ± chemotherapy (chemo) vs standard of care (SOC; chemo ± bevacizumab) in BRAF V600E-mutant metastatic colorectal cancer (mCRC). The study previously met one of its dual primary endpoints (EPs) demonstrating clinically meaningful and statistically significant improvement in confirmed objective response rate (ORR) by blinded independent central review (BICR) in the ORR subset. These results were the basis for the FDA accelerated approval of EC+mFOLFOX6 for BRAF V600E-mutant mCRC, including in the 1L, under Project Frontrunner. Here, we report the primary analysis of progression-free survival (PFS) by BICR, updated interim analysis of OS, updated safety, and other analyses. Methods: Eligible patients (pts) with untreated BRAF V600E-mutant mCRC were randomized 1:1:1 to receive EC, EC+mFOLFOX6, or SOC; EC arm enrollment was closed after a protocol amendment. Dual primary EPs: ORR and PFS by BICR (EC+mFOLFOX6 vs SOC); key secondary EP: OS (EC+mFOLFOX6 vs SOC). Results: 637 pts were randomized to EC, EC+mFOLFOX6, or SOC. Baseline demographics and disease characteristics were generally balanced between arms. EC+mFOLFOX6 (data cutoff: Jan 6, 2025) demonstrated a clinically meaningful and statistically significant PFS improvement vs SOC, meeting the other dual primary EP; HR=0.53 (95% CI 0.407, 0.677; P<0.0001); median PFS 12.8 vs 7.1 mo. OS was clinically meaningful and statistically significant vs SOC; HR=0.49 (95% CI 0.375, 0.632; P<0.0001); median OS 30.3 vs 15.1 mo. Median PFS and OS in the EC arm were 6.8 and 19.5 mo. These data and response data for all randomized pts are shown in the table. Serious treatment-emergent adverse events occurred in 30%, 46%, and 39% of pts in the safety analysis set. Safety was consistent with that known for each agent. Conclusions: BREAKWATER demonstrated clinically meaningful and statistically significant PFS and OS improvements with EC+mFOLFOX6 vs SOC and manageable toxicities. EC+mFOLFOX6 is potentially practice changing as the new SOC. Clinical trial information: NCT04607421 . ECn=158 EC+mFOLFOX6n=236 SOCn=243 EC+mFOLFOX6vs SOCHR (95% CI)P-value a Median PFS b , mo (95% CI) 6.8(5.7, 8.3) 12.8(11.2, 15.9) 7.1(6.8, 8.5) 0.53 (0.407, 0.677) <0.0001 Median OS, mo (95% CI) 19.5(17.6, 22.5) 30.3(21.7, NE) 15.1(13.7, 17.7) 0.49 (0.375, 0.632)<0.0001 ORR, b % (95% CI) 45.6(38.0, 53.3) 65.7(59.4, 71.4) 37.4(31.6, 43.7) Median DOR b , mo (95% CI) c 7.0 (4.2, 11.6) 13.9 (10.9, 18.5) 10.8 (7.6, 13.4) DOR b ≥6 mo, n (%) c 29 (40.3) 110 (71.0) 38 (41.8) DOR b ≥12 mo, n (%) c 15 (20.8) 54 (34.8) 16 (17.6) Median time to response, b wk (range) c 6.6(4.3-86.4) 7.0(5.1-103.6) 7.3 (5.4-48.0) a 1-sided stratified log rank test. b By BICR. c Responders: n=72, n=155, and n=91. DOR, duration of response.

PURPOSE Tumor treating fields (TTFields) use alternating electric fields to disrupt cancer cell proliferation. Feasibility of TTFields therapy with gemcitabine/nab-paclitaxel was previously demonstrated in patients with advanced pancreatic adenocarcinoma. PANOVA-3 was designed to confirm safety and efficacy of TTFields in patients with unresectable locally advanced pancreatic adenocarcinoma (LA-PAC). METHODS In this global phase III trial, 571 patients with newly diagnosed LA-PAC were randomly assigned to receive gemcitabine 1,000 mg/m 2 and nab-paclitaxel 125 mg/m 2 by intravenous infusion once a day on days 1, 8, and 15 of a 28-day cycle with or without TTFields. The primary end point was overall survival (OS). Secondary end points included progression-free survival (PFS), local PFS, pain-free survival, and overall response rate (ORR). Distant PFS was analyzed post hoc. RESULTS OS was significantly prolonged using TTFields with gemcitabine/nab-paclitaxel versus gemcitabine/nab-paclitaxel (median, 16.2 months [95% CI, 15.0 to 18.0] v 14.2 months [95% CI, 12.8 to 15.4]; hazard ratio [HR], 0.82 [95% CI, 0.68 to 0.99]; P = .039). PFS, local PFS, and ORR were not improved. Pain-free survival was significantly prolonged with TTFields with gemcitabine/nab-paclitaxel (median, 15.2 months [95% CI, 10.3 to 22.8] v 9.1 months [95% CI, 7.4 to 12.7]; HR, 0.74 [95% CI, 0.56 to 0.97]; P = .027), as was distant PFS (median, 13.9 months [95% CI, 12.2 to 16.8] v 11.5 months [95% CI, 10.4 to 12.9]; HR, 0.74 [95% CI, 0.57 to 0.96]; P = .022). Device-related skin adverse events (AEs) were experienced by 76.3% of patients. Most device-related skin AEs were mild to moderate, with 7.7% of patients reporting a grade 3 AE. CONCLUSION This study demonstrated significant OS, pain-free survival, and distant PFS benefits for TTFields with gemcitabine/nab-paclitaxel versus gemcitabine/nab-paclitaxel in patients with unresectable LA-PAC, with no additive systemic toxicity.

PURPOSE Several lines of treatment can be used sequentially in patients with metastatic colorectal cancer. We investigated the evolution of patient/tumor characteristics and their prognostic impact across treatment lines to develop an overall prognostic score (OPS). PATIENTS AND METHODS Individual patient data from 48 randomized trials were analyzed. The end point was overall survival (from random assignment to death). Missing data were imputed. The complete data set was then separated into construction (80%) and validation sets (20%). The Cox's model was used to define risk groups for survival using the OPS. The discrimination capability was assessed in each treatment-line via bootstrapping to obtain optimism-corrected calibration and discrimination C-indices. Internal validation was done in the validation set. RESULTS A total of 37,560 patients (26,974 in first-line [1L], 7,693 in second-line [2L], and 2,893 in third-line [3L]) were analyzed. Some clinical, biological, and molecular characteristics of patients/tumors included in therapeutic trials evolve over the lines. Seven independent prognostic variables were retained in the final multivariate model common to all lines: Eastern Cooperative Oncology Group performance status, hemoglobin, platelet count, WBC/absolute neutrophil count ratio, lactate dehydrogenase, alkaline phosphatase, and the number of metastatic sites. The OPS was used to define four patient subgroups with significantly different prognoses in 1L, 2L, and 3L, separately, with adequate C-indices: 0.65, 0.66, and 0.69 in the construction set and 0.65, 0.66, and 0.68 in the validation set, respectively. The OPS was not predictive, with 3L drugs ( v placebo) or subsequent line (2L/1L or 3L/2L) extending survival in all prognostic groups. CONCLUSION The same prognostic model using practical variables can be used before all treatment lines. The OPS could better stratify patients in future clinical trials and help to therapeutic decision in routine practice.