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Abstract Background Disruption of the blood–brain barrier (BBB) in high-grade brain tumors is characterized by contrast accumulation on diagnostic imaging. This window of opportunity study correlates contrast imaging features with the tumor distribution of BBB-permeable (levetiracetam) and -impermeable (cefazolin) drugs. Methods Patients with a clinical diagnosis of a high-grade brain tumor underwent MRI for surgical planning. Cefazolin and levetiracetam were administered prior to skin incision, and serial plasma and image-registered tumor samples were collected during the operation. Drug levels were measured by LC-MS/MS, tissue drug levels were corrected for residual blood, and tumor-to-plasma concentration ratios were calculated. Intraoperative microdialysis was performed in a subset of patients to measure the same two drugs. Results Tumor (n = 125) and plasma (n = 261) samples were available for analysis from 42 operative cases. Across all samples, the tumor-to-plasma ratio was significantly lower for cefazolin (marginal mean [MM]: 0.15, 95% CI: 0.11–0.19) as compared to levetiracetam (MM: 0.70, 95% CI: 0.64–0.75; P < .001). When compared between contrast-enhancing and non-enhancing regions, tumor-to-plasma ratios for cefazolin varied by 4.4-fold (0.27, 95% CI: 0.20–0.35 vs. 0.06, 95% CI: 0.04–0.08, respectively; P < .001), and varied for levetiracetam by 1.4-fold (0.88, 95% CI: 0.78–0.97 vs. 0.61, 95% CI: 0.55–0.66, respectively; P < .001). These results were confirmed with the intra-operative microdialysis and a population pharmacokinetic analysis. Conclusions This study demonstrates significant inter- and intra-tumoral heterogeneity in drug delivery for both levetiracetam and cefazolin within high-grade brain tumors that is not necessarily predicted by clinical MR imaging and may reflect tumor-induced changes in both perfusion and BBB integrity.

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.

Abstract Background Dasatinib is an oral inhibitor of the Src kinase family, with preclinical data indicating impact on gliomagenesis, tumor invasion, and radiosensitivity. Methods North Central Cancer Treatment Group N0877 is a phase 1 dose escalation and phase II randomized study evaluating the maximum tolerated dose (MTD), safety, and efficacy of dasatinib with radiation and temozolomide (TMZ) for glioblastoma. Following identification of the MTD, adult patients with a histologic diagnosis of glioblastoma were randomized 2:1 between dasatinib given with standard concurrent and adjuvant TMZ, versus placebo with standard concurrent and adjuvant TMZ. Radiation dose was 60 Gy in 30 fractions. The primary endpoint was overall survival (OS). Secondary endpoints included progression-free survival (PFS), toxicity, and quality of life. Results Thirteen patients were enrolled in the phase I component and established the MTD and phase II dose of 150 mg given daily. A total of 204 patients were enrolled in the phase II component. OS was not different between arms (median OS 15.6 months for dasatinib compared to 19.3 months for placebo, hazard ratio:1.21 favoring placebo, 95% CI: 0.88–1.65, log-rank P-value: .238). Similarly, PFS was not significantly different between the dasatinib and placebo arms. There was a significant increase in anemia, nausea, and creatinine elevation with dasatinib, but significantly more grade 3 lymphopenia with placebo. Conclusions The addition of dasatinib to standard chemoradiation did not improve outcomes for patients with glioblastoma. Clinical Trial Identifier NCT00869401.

3520 Background: Recent analyses highlight nonhierarchical outcomes using the 8 th Edition AJCC staging system for CC. For instance, the 5-year survival rate for stages I and IIIa patients (pts) closely align. Additionally, tumor deposits (TDs) have been established as significant prognostic indicators. The AJCCCCEP commissioned this study to develop an updated pathological staging system for CC focused specifically on pts without distant metastasis (M0), while retaining the existing stage IV classification. Methods: Individual patient data (IPD) from pts diagnosed with cc (2010- 2017) in the NCDB were divided into training (70%) and internal validation (30%) datasets. External validation used IPD from clinical trials. The primary endpoint was overall survival (OS). Risk classification development for M0 pts incorporated ungrouped data on pathologic T categories, the number of involved regional lymph nodes (LN+), and TD counts. Recursive partitioning and regression tree analyses were applied to construct hierarchical staging levels. Pre-specified criteria required survival probabilities to be consecutive and show clear separations using Kaplan-Meier (KM) estimates with pairwise log-rank test P of < 0.005 for the training and < 0.05 for validation analyses. Results: Data from 281,997 pts (median age 67 years, 50% male, 81% white, 55% T3, 19% T4, 44% N+, 26% M+, and 11% with ≥1 TD) were analyzed, with a median follow-up of 7.3 years. The updated staging system (Table) met pre-specified criteria, with all observed pairwise P < 0.0001 in the development and internal validation sets. KM OS curves displayed a hierarchical separation across all sub-levels after the 1 st year of diagnosis. Consistent results were seen in pts treated with adjuvant chemotherapy in 4 trials (all pair-wise P < 0.0001). Conclusions: The proposed pathological staging system for M0 pts fulfills pre-specified criteria for hierarchical risk stratification, validated both internally and externally, and provides an evidence-based update. Pending review process, the AJCCCCEP will recommend that these changes be made to the Version 9 staging protocol for colon cancer to improve prognostication for CC pts. Stage T, # of LN+, # of TD M % of pts 1y OS (CI), % 3y OS (CI), % 5y OS (CI), % I T1, 0, 0 0 5 96 (95-97) 91 (90-92) 84 (83-86) IIa T2, 0, 0 0 10 95 (94-95) 88 (88-89) 80 (79-81) IIb T1, 0, 1+T1, 1+, 0T2, 0, 1+T2, 1-4, 0T3, 0, 0 0 27 93 (92-93) 84 (84-85) 75 (75-76) IIIa T1, 1+, 1+T2, 1-4, 1+T2, 5+, 0T3, 0, 1+T3, 1-4, 0 0 14 92 (91-92) 80 (80-81) 71 (70-72) IIIb T2, 5+, 1+T3, 1-4, 1+T3, 5+, 0T4a, 0-4, 0T4b, 0-2, 0 0 13 86 (86-87) 69 (68-70) 58 (57-59) IIIc T3, 5+, 1+T4a, 0-4, 1+T4a, 5+, anyT4b, 0-2, 1+T4b, 3+, any 0 5 78 (77-80) 53 (51-54) 40 (38-41) IVa Any 1a 19 59 (58-60) 28 (28-29) 17 (16-18) IVb Any 1b 7 43 (42-44) 14 (13-14) 6 (6-7) CI: 95% confidence internal; Peritoneum involvement data were not available before 2018 in NCDB. Thus, IVa/b were based on 7 th Edition.

TPS3634 Background: For patients with oligometastatic colorectal cancer (CRC), aggressive local therapy of isolated metastases, particularly in the liver, has been associated with long-term progression-free and overall survival (OS) primarily based on retrospective evidence. However, in patients with limited metastatic CRC that is deemed inoperable or those with additional disease outside of the liver or lungs, the role of local ablative therapies, including microwave ablation (MWA) and stereotactic body radiation therapy (SBRT), to render patients disease free is less clear. Despite the long history of treating oligometastatic CRC with local therapy, which is largely provider biased, questions remain regarding the benefit of extending the paradigm of metastatic directed therapy to patients with more extensive disease. This trial seeks to use a pragmatic multimodality approach that mirrors the current clinical dilemma. This study is designed to evaluate the safety and efficacy of adding total ablative therapy (TAT) of all sites of disease to standard of care systemic treatment in those with limited metastatic CRC. Methods: A022101/NRG-GI009 is a National Clinical Trials Network randomized phase III study planned to enroll 364 patients with newly diagnosed metastatic CRC (BRAF wild-type, microsatellite stable) without peritoneal metastasis or liver-only disease on baseline imaging. Patients receive first-line systemic therapy for 12-39 weeks. Patients with ≤4 sites of metastatic disease following initial systemic therapy that are amenable to any combination of surgical resection, MWA, and/or SBRT are then randomized 1:1, stratified by number of metastatic organ sites (1-2 vs. 3-4), timing of metastatic disease diagnosis (de novo vs. secondary), and presence of metastatic disease outside the liver/lungs in at least 1 site. Patients in Arm 1 will receive TAT consisting of treatment of all metastatic sites with SBRT, MWA, and/or surgical resection followed by standard of care systemic therapy. Patients in Arm 2 will continue with standard of care systemic therapy alone. The primary endpoint is OS. Secondary endpoints include event-free survival, treatment-related toxicities, and local recurrence with exploratory biomarker analyses. The study needs 346 evaluable patients combined in the 2 arms to demonstrate an improvement in OS with a hazard ratio of 0.7 to provide 80% power with a one-sided alpha of 5%. The trial utilizes a group sequential design with two interim analyses (25% and 50% of events) for futility. The trial activated in January 2023 and recruitment is ongoing. Support: U10CA180821, U10CA180882; https://acknowledgments.alliancefound.org. U10CA180820 (ECOG-ACRIN); U10CA180868 (NRG); U10CA180888 (SWOG); Clinical trial information: NCT05673148 .

PURPOSE Newly approved drugs and combinations treating multiple myeloma (MM) have resulted in substantial improvements in patients' survival. To deliver rapid access to newer therapies, an earlier end point to expedite clinical trials is needed. Our objective was to evaluate the minimal residual disease–negative complete response (MRD-CR) as an intermediate end point for progression-free survival (PFS) and overall survival (OS) in newly diagnosed (ND) transplant-eligible (NDTE) patients, ND transplant-ineligible (NDTinE) patients, and patients with relapsed/refractory (RR) MM. PATIENTS AND METHODS Individual patient data from 20 randomized multicenter trials were collected. Eleven studies (4,773 patients) with sufficient data were analyzed to evaluate whether 9- or 12-month MRD-CR classified at a 10 –5 threshold could be reasonably likely to predict the clinical benefit of new agents regarding PFS and OS. Global odds ratio (OR) was estimated using the bivariate Plackett Copula model. Supportive evaluation included correlations of the treatment effects on MRD-CR end points and PFS/OS, evaluated by both linear regression ( R 2 weighted least squared ) and Copula ( R 2 Copula ) models. RESULTS The analysis demonstrated that both 9- and 12-month MRD-CR strongly correlated with PFS at patient level in NDTE patients, NDTinE patients, and patients with RRMM. Global ORs ranged from 3.06 to 16.24, all with 95% CIs excluding 1.0. Encouraging trial-level correlations ( R 2 , 0.61-0.70) were observed by pooling three populations and were stronger ( R 2 , 0.67-0.78) in the ND population. Similar results were observed for OS. CONCLUSION Our findings provided the support for use of MRD-CR classified at a 10 –5 threshold at either 9 or 12 months after starting of the treatment, as an intermediate end point to support accelerated approvals, in future trials in NDTE patients, NDTinE patients, and patients with RRMM.

TPS309 Background: Patients with oligometastatic colorectal cancer (CRC) often experience long-term progression-free survival and overall survival (OS) following aggressive local treatment of isolated metastases, especially in the liver. However, the effectiveness of local ablative therapies, such as microwave ablation (MWA) and stereotactic body radiation therapy (SBRT), in patients with inoperable limited metastatic CRC or those with additional metastases outside the liver or lungs, remains uncertain. Despite the historical use of local therapy for oligometastatic CRC, often influenced by provider bias rather than strong evidence, questions persist about the potential benefits of applying this approach to patients with more extensive disease. This trial aims to address this clinical challenge by evaluating the safety and efficacy of adding total ablative therapy (TAT) of all disease sites to standard systemic treatment in patients with limited metastatic CRC. Methods: A022101/NRG-GI009 is a randomized phase III study within the National Clinical Trials Network, set to enroll 364 patients with newly diagnosed metastatic CRC (BRAF wild-type, microsatellite stable). Patients with liver-only metastatic disease are excluded. Pre-registration during first-line systemic therapy induction is encouraged. Eligible lesions must be treatable with surgical resection, MWA, and/or SBRT. Patients without significant radiographic progression after 12-39 weeks of first-line systemic therapy, with 4 or fewer disease sites post-induction chemotherapy, will be randomized 1:1. Randomization will be stratified by the number of metastatic organ sites (1-2 vs. 3-4), timing of metastatic disease diagnosis (de novo vs. secondary), and the presence of metastatic disease outside the liver/lungs in at least one site. Patients in Arm 1 will receive TAT, targeting all metastatic sites with a combination of surgical resection, MWA, and/or SBRT, followed by standard systemic therapy. Patients in Arm 2 will continue with standard systemic therapy alone. The choice of systemic therapy is at the discretion of the medical oncologist and may include continued therapy, maintenance chemotherapy, or observation. The primary endpoint is OS, with secondary endpoints including event-free survival, treatment-related toxicities, and local recurrence. Exploratory biomarker analyses will also be conducted. The study requires 346 evaluable patients across the two arms to demonstrate an OS improvement with a hazard ratio of 0.7, providing 80% power with a one-sided alpha of 5%. The trial employs a group sequential design with two interim analyses (at 25% and 50% of events) to assess futility. The trial began in January 2023, and patient recruitment is ongoing. Clinical trial information: NCT05673148 .

Importance The prognosis for patients with glioblastoma is poor following standard therapy with surgical resection, radiation, temozolomide, and tumor-treating fields. Objectives To evaluate the combination of veliparib and temozolomide in glioblastoma based on preclinical data demonstrating significant chemosensitizing effects of the polyadenosine diphosphate-ribose polymerase 1/2 inhibitor veliparib when combined with temozolomide. Design, Setting, and Participants Patients with newly diagnosed glioblastoma with MGMT promoter hypermethylation who had completed concomitant radiation and temozolomide were enrolled between December 15, 2014, and December 15, 2018, in this Alliance for Clinical Trials in Oncology trial. The data for this analysis were locked on April 21, 2023. Interventions Patients were randomized and treated with standard adjuvant temozolomide (150-200 mg/m 2 orally, days 1-5) combined with either placebo or veliparib (40 mg orally, twice daily, days 1-7) for 6 cycles. Main Outcomes and Measures The primary end point for the phase 3 portion of the trial was overall survival (OS). Results There were 322 patients randomized during the phase 2 accrual period and an additional 125 patients randomized to complete the phase 3 accrual, for a total of 447 patients in the final phase 3 analysis. The median (range) age for patients was 60 (20-85) years and 190 patients (42.5%) were female. The median OS was 24.8 months (90% CI, 22.6-27.7) for the placebo arm and 28.1 months (90% CI, 24.3-33.3) for the veliparib arm ( P = .17). The difference in survival did not meet the prespecified efficacy end point. However, there was a separation of the survival curves that favored the veliparib arm over 24 to 48 months of follow-up. The experimental combination was well tolerated with an acceptable elevation in grade 3 or 4 hematologic toxic effects. Conclusions and Relevance This trial found that adding veliparib to adjuvant temozolomide did not significantly extend OS in patients with newly diagnosed, MGMT -hypermethylated glioblastoma. Trial Registration ClinicalTrials.gov Identifier: NCT02152982

TPS4205 Background: Multiple lines of evidence support the use of platinum-based chemotherapy for patients with homologous recombination deficiency-associated pancreatic adenocarcinoma (HRD PDAC; 15-20%). However, the impact of the specific platinum agent used remains uncertain. Mechanistically, oxaliplatin and cisplatin act distinctly on cancer cells, reflected in disparate toxicity profiles and target disease indications; furthermore, preclinical studies have shown that BRCA2-deficient cell lines and mice demonstrate significantly greater sensitivity to cisplatin compared to oxaliplatin. While oxaliplatin, part of the FOLFIRINOX regimen, represents the most commonly used platinum analogue for PDAC, clinical data shows that cisplatin (in combination with gemcitabine) can produce robust response rates (~70%) specifically in patients with germline BRCA/PALB2-mutated metastatic PDAC. We therefore designed a randomized clinical trial (PLATINUM) through the Alliance for Clinical Trials in Oncology cooperative group to assess the optimal chemotherapy regimen in patients with HRD-associated metastatic PDAC following front-line FOLFIRINOX and to test the hypothesis that a platinum switch strategy will be beneficial. Methods: The study consists of a seamless phase II/III design, with the primary endpoint of the phase III component being overall survival. Eligible patients will have metastatic PDAC, a confirmed pathogenic BRCA1/2 or PALB2 mutation (somatic or germline), and demonstrated disease progression on front-line FOLFIRINOX, with or without subsequent PARP inhibitor maintenance. Patients will be randomized 1:1 to receive (1) the de facto standard of gemcitabine plus nab-paclitaxel; or (2) the experimental 3-drug combination of gemcitabine, nab-paclitaxel, and cisplatin (NABPLAGEM), which has been previously studied in non-biomarker-selected patients with advanced biliary tract cancer (SWOG1815) and metastatic PDAC. Both treatment arms will use a once every other week dosing schedule. A total of 100 patients will be enrolled, which provides 90% power to detect an effect size of hazard ratio 0.5 (median OS of 18 vs 9 months) at a one-sided alpha of 0.05. Reports containing efficacy, adverse events, and administrative information will be provided to the Alliance DSMB every 6 months. Planned correlatives include ctDNA analysis for BRCA reversion mutations in all patients, as well as whole genome and transcriptome sequencing in an optional biopsy cohort. This study was activated in December 2023. Clinical trial information: NCT06115499 .