Alliance for clinical trials in Oncology (Alliance) trial A022101/NRG-GI009: a pragmatic randomized phase III trial evaluating total ablative therapy for patients with limited metastatic colorectal cancer: evaluating radiation, ablation, and surgery (ERASur)

Abstract Background For patients with liver-confined metastatic colorectal cancer (mCRC), local therapy of isolated metastases has been associated with long-term progression-free and overall survival (OS). However, for patients with more advanced mCRC, including those with extrahepatic disease, the efficacy of local therapy is less clear although increasingly being used in clinical practice. Prospective studies to clarify the role of metastatic-directed therapies in patients with mCRC are needed. Methods The Evaluating Radiation, Ablation, and Surgery (ERASur) A022101/NRG-GI009 trial is a randomized, National Cancer Institute-sponsored phase III study evaluating if the addition of metastatic-directed therapy to standard of care systemic therapy improves OS in patients with newly diagnosed limited mCRC. Eligible patients require a pathologic diagnosis of CRC, have BRAF wild-type and microsatellite stable disease, and have 4 or fewer sites of metastatic disease identified on baseline imaging. Liver-only metastatic disease is not permitted. All metastatic lesions must be amenable to total ablative therapy (TAT), which includes surgical resection, microwave ablation, and/or stereotactic ablative body radiotherapy (SABR) with SABR required for at least one lesion. Patients without overt disease progression after 16–26 weeks of first-line systemic therapy will be randomized 1:1 to continuation of systemic therapy with or without TAT. The trial activated through the Cancer Trials Support Unit on January 10, 2023. The primary endpoint is OS. Secondary endpoints include event-free survival, adverse events profile, and time to local recurrence with exploratory biomarker analyses. This study requires a total of 346 evaluable patients to provide 80% power with a one-sided alpha of 0.05 to detect an improvement in OS from a median of 26 months in the control arm to 37 months in the experimental arm with a hazard ratio of 0.7. The trial uses a group sequential design with two interim analyses for futility. Discussion The ERASur trial employs a pragmatic interventional design to test the efficacy and safety of adding multimodality TAT to standard of care systemic therapy in patients with limited mCRC. Trial registration ClinicalTrials.gov: NCT05673148, registered December 21, 2022

SMAD4 loss in colorectal cancer: Correlation with recurrence, chemoresistance, and immune infiltrate

587 Background: Few markers reliably identify colorectal cancer (CRC) patients at risk of recurrence and death. SMAD4 loss occurs in 10-20% of cases and has shown promise in identifying high-risk stage II/III patients. We examined SMAD4 status and association with clinical/pathologic features in 446 stage I-IV CRC patients at Memorial Sloan Kettering (MSK). Methods: Patients undergoing curative resection were included (1981-2010). Familial polyposis syndrome patients and those with inadequate tissue were excluded. Tissue microarrays were constructed (n=364). Immunohistochemistry for SMAD4 and mismatch repair (MMR) proteins was completed. SMAD4 nuclear stain intensity was scored (scale=0-3; 0=loss). On whole sections, MMR proteins (present or absent), tumor-infiltrating lymphocytes (TILs) and peritumoral lymphocyte aggregates (PLAs) were scored (scale=0-3). Associations between clinical/pathologic features and SMAD4 loss vs. retention were analyzed. Kaplan-Meier estimates and log-rank test were used for recurrence-free and overall survival analyses (RFS and OS). Results: SMAD4 loss was noted in 13%. Median age at diagnosis was 53 years, and 51% were male. The cohort consisted of 61% hindgut tumors and 62% stage II/III patients. With up to 33 years of follow-up, the mean was 6 years. SMAD4 loss correlated with higher tumor and nodal stage, adjuvant therapy use, and lower TIL and PLA scores (pmedian) were noted to have worse OS with SMAD4 loss (p<0.01). SMAD4 loss did correlate with worse RFS (p=0.02), persisting even when excluding MMR-deficient patients. Additionally, SMAD4 loss was associated with worse RFS in both the adjuvant chemotherapy group (median RFS=3.8 vs. 13 years; p=0.06) and the resection-only group (median RFS=4.2 years vs. not yet reached; p< 0.01). Conclusions: SMAD4 loss correlates with worse RFS and resistance to adjuvant therapy. SMAD4 loss also correlates with lower TIL and PLA scores. Future work will address chemoresistance mechanisms, relevance to adjuvant therapy use, and loss of immune infiltrate in SMAD4-null tumors