Malla, Midhun

PURPOSE Deficient mismatch repair/microsatellite instability (dMMR, MSI-H) in biliary tract cancers (BTCs) is observed in 1%-5% of tumors. MSI-H across solid tumors has demonstrated durable response to immune checkpoint inhibitors (ICIs) regardless of the anatomic location. Here, we describe clinical outcomes and surgical conversion of MSI-H BTC treated with ICIs. Patients and Methods We conducted a multicenter, retrospective analysis of BTC patients with dMMR/MSI-H between 2017 and 2024 at Mayo Clinic, University of Michigan, and University Hospitals Seidman Cancer Center. Outcomes of interest were surgical resection rate, rate of pathologic response, 2-year overall survival (OS; time from initiation of treatment to death/last follow-up), and time to treatment discontinuation (TTD; time from initiation of treatment to cessation because of any cause). Analyses were descriptive. RESULTS Thirty patients with MSI-H BTC were identified: 19 with cholangiocarcinoma, three with gallbladder cancer, and 8 with BTC undefined. The median age at diagnosis was 61.5 years (range, 26-86). Twenty-six (86.7%) patients had advanced stage at diagnosis. Twenty-seven patients (90%) received first-line systemic therapy, and 13 (48.1%) continued onto second line. Six patients (23.1%) were restaged to resectable from advanced disease after ICI therapy and underwent resection; all remained recurrence-free at last follow-up. Of these six patients, 3 (50%) achieved a pathologic complete response. Among those receiving first-line therapy, the median TTD was 9.9 months (95% CI, 5.7 to 14.5 months) and the 2-year OS was 73% (95% CI, 56% to 94%). CONCLUSION ICI therapy in patients with MSI-H BTC demonstrated durable response and downstaged some BTC to a resectable stage. dMMR/MSI-H should be performed up-front to guide treatment decisions.

11177 Background: Early detection of recurrence after curative-intent treatment is a critical priority, traditional imaging often detects relapse when disease burden is high, potentially limiting treatment efficacy. ctDNA has emerged as an established prognostic biomarker for molecular residual disease (MRD) detection and early relapse. We performed a real-world meta-analysis on published datasets that utilized personalized, tumor-informed ctDNA testing to assess its performance across tumor types and clinical management approaches. Methods: Real-world studies published from December 2022 to December 2025 using the personalized, tumor-informed Signatera ctDNA assay (Natera, Inc.) were included. Eligibility required ctDNA assessment in the MRD (2–16 weeks post-surgery (histology dependent)/pre adjuvant therapy (ACT)) and/or surveillance (post-ACT/end of the MRD window if no ACT was given) settings, with outcomes stratified by ctDNA status and hazard ratios (HR) reported from univariable or time-dependent Cox regression analysis. Exclusions included: clinical trials, biobanks, metastatic disease treated with palliative intent, case reports, reviews, editorials, or commentaries. Clinical outcomes were harmonized into a composite event-free survival (EFS) endpoint (time to recurrence, progression, or death). Pooled HRs and 95% CIs were estimated using random and fixed effects models and heterogeneity between studies was assessed using the I 2 and Cochran’s Q test. Median lead time from ctDNA-positivity to radiographic or clinical recurrence was summarized when available. Results: We identified 18 eligible publications comprising 3,004 unique patients across 15 solid tumor types. During the MRD window, ctDNA positivity was associated with a significantly increased risk of an EFS event compared with ctDNA negativity (pooled HR: 8.15; 95% CI: 6.12–10.85, I 2 = 0.00%, P = 0.844, n = 13). During the surveillance window, inclusive of post-definitive treatment, ctDNA positivity conferred an even greater EFS risk (pooled HR: 18.30; 95% CI: 14.17–23.65, I 2 = 0%, P = 0.911 for heterogeneity, n = 16). Across studies, ctDNA detection during surveillance preceded radiographic or clinical recurrence by a median of 3.20 months (95% CI: 2.50-4.10, P < 0.0001, n = 10), although this varied substantially by study/tumor type (I 2 = 80.9%). Conclusions: In this pan-cancer real-world meta-analysis, ctDNA positivity assessed using a tumor-informed assay was highly prognostic following curative-intent therapy at all timepoints evaluated with low heterogeneity between studies. These findings support the broad clinical utility of tumor-informed ctDNA testing for post-treatment risk stratification and longitudinal disease monitoring across solid tumors.

Objective: In this study, we evaluate the utility of ctDNA analysis in a large cohort of patients for whom ctDNA testing was ordered commercially with real-world application. Summary Background Data: Circulating tumor DNA (ctDNA) has emerged as a prognostic and predictive biomarker for assessing post-surgical molecular residual disease (MRD) and response to treatment. Methods: A real-world data analysis was performed using commercial ctDNA testing (SignateraTM) from patients (N=795, n=5,971 plasma samples) with stage I-III colon cancer treated at multiple US institutions. The association of ctDNA detection within the MRD window, during surveillance, and the impact of ACT was correlated with patient outcomes. Results: ctDNA-positive patients during the MRD window and surveillance showed significantly shorter DFS compared to ctDNA-negative patients (hazard ratio (HR): 9.85, P<0.0001; HR: 26.91, P<0.0001). Multivariate analysis of the MRD window revealed ctDNA-positivity as the most significant factor associated with inferior DFS (adjHR: 7.7, P<0.001). MRD-positive patients who received ACT showed improved DFS compared to patients observed post-surgery (adjHR: 6.1, FDR adj P=0.0007). No ACT benefit was observed in MRD-negative patients (adj HR: 1.20, FDR adj P=0.768). On evaluating ctDNA dynamics from MRD to surveillance, patients who remained ctDNA-positive or converted from negative to positive showed a significantly inferior DFS (HR: 34.40, P<0.0001; HR: 13.65, P<0.0001) compared to persistently ctDNA-negative patients. Conclusions: Postsurgical ctDNA detection is prognostic of relapse and potentially predictive of ACT benefit in patients with resectable colon cancer, which may enable personalized surveillance, intervention, and/or trial options, ultimately improving patient outcomes.

The determination of an optimal treatment plan for an individual patient with rectal cancer is a complex process. In addition to decisions relating to the intent of rectal cancer surgery (ie, curative or palliative), consideration must also be given to the likely functional results of treatment, including the probability of maintaining or restoring normal bowel function/anal continence and preserving genitourinary functions. Particularly for patients with distal rectal cancer, finding a balance between curative-intent therapy while having minimal impact on quality of life can be challenging. Furthermore, the risk of pelvic recurrence is higher in patients with rectal cancer compared with those with colon cancer, and locally recurrent rectal cancer is associated with a poor prognosis. Careful patient selection and the use of sequenced multimodality therapy following a multidisciplinary approach is recommended. These NCCN Guidelines Insights detail recent updates to the NCCN Guidelines for Rectal Cancer, including the addition of endoscopic submucosal dissection as an option for early-stage rectal cancer, updates to the total neoadjuvant therapy approach based on the results of recent clinical trials, and the addition of a “watch-and-wait” nonoperative management approach for clinical complete responders to neoadjuvant therapy.

Colorectal cancer (CRC) is the fourth most frequently diagnosed cancer and the second leading cause of cancer death in the United States. Management of disseminated metastatic CRC involves various active drugs, either in combination or as single agents. The choice of therapy is based on consideration of the goals of therapy, the type and timing of prior therapy, the mutational profile of the tumor, and the differing toxicity profiles of the constituent drugs. This manuscript summarizes the data supporting the systemic therapy options recommended for metastatic CRC in the NCCN Guidelines for Colon Cancer.

Abstract Introduction: The development of hepatocellular carcinoma (HCC) is associated with underlying chronic liver disease from viral hepatitis or nonviral etiologies, such as nonalcoholic fatty liver disease (NAFLD) and alcoholic liver disease. An area of current research interest is the relationship between etiology of chronic liver disease in HCC patients and the response to specific treatment modalities. The purpose of this study is to identify prognostic indicators and compare survival outcomes among HCC patients within an Appalachian patient population. Methods: A single-institution, retrospective chart review was conducted for all patients diagnosed with HCC between August 2009 and March 2017 at West Virginia University Hospital. Patient demographics, tumor characteristics, laboratory data and treatment information were obtained from the electronic medical record (EMR). Survival analyses were performed using Kaplan-Meier method and multivariable Cox regression analysis. Results: The study sample (n=100) had a mean age of 62 years and was comprised of 82% males and 18% females. Nonviral etiologies of chronic liver disease were predominant (55%) over chronic viral hepatitis (45%). Significant adverse prognostic indicators of overall survival (OS) were Child-Pugh class C and tumor size &gt;5 cm at diagnosis (p&lt;0.0001, log-rank test). Patients who received liver-directed therapy (LDT) or liver resection had greater OS compared to those not treated with either modality (15.5 vs. 2.0 months, p&lt;0.0001). Liver ablation or resection as initial modes of treatment had greater OS compared to those who initially received transarterial chemoembolization (TACE) or transarterial radioembolization (TARE) (17.2 vs 14.9 months, p&lt;0.05). Patients who received TACE or TARE (n=60) as initial treatment had characteristics of advanced disease, with 45% having a tumor greater than 5 cm in size and 77% having multifocal unilobar or bilobar tumors. Among all patients who received LDT or resection, post-treatment albumin-bilirubin grade (ALBI) of 1 or 2 correlated with greater OS than grade 3 (22.5 vs 6.2 months, p&lt;0.0001). In the multivariate Cox analysis, tumor size, Child-Pugh class and mode of initial treatment (resection/ablation vs. TACE/TARE) were independent predictors of OS (p&lt;0.05). Conclusions: Treatment with LDT or liver resection correlated with greater overall survival in this predominantly nonviral cohort of HCC patients. Post-treatment ALBI grade correlated with overall survival and may have prognostic value in guiding clinical management. Mode of initial treatment was a predictor of overall survival, but further studies are needed to compare tumor characteristics between groups. Research is ongoing to evaluate the relationship between chronic liver disease etiology and survival among HCC patients treated with LDT, immunotherapy or a combination of both. Citation Format: Michelle Hartzell, Gary Monroe, Jon Shakesprere, Sijin Wen, J. Wallis Marsh, Jacob Fuqua, Robert Grammer, Beau Toskich, Midhun Malla. Prognostic indicators and outcomes of hepatocellular carcinoma (HCC) in an Appalachian population [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6745.

e16076 Background: Median overall survival (mOS) of patients (pt) with metastatic colorectal cancer (mCRC) has improved steadily over the past two decades. However, epidemiological data suggest that cancer outcomes for rural compared to urban dwelling pts are worse. In this study, we retrospectively compared progression free survival (PFS) and OS among mCRC pts residing in urban versus rural areas enrolled in N9741 (1997-2004) and CALGB 80405 (2005-2012) clinical trials. Methods: Zip code data from the Centers for Disease Control (CDC) were used to classify pts into rural or urban dwellers. Chi-square and Kruskal Wallis analyses were used to compare the groups. Survival outcomes were evaluated using Kaplan-Meier estimates, compared by stratified log rank and cox proportional hazards models. Results: In N9741 and 80405 respectively, 217 (35%) and 521 (21%) pts resided in rural areas. Median age of mCRC pts at diagnosis was 60.5 yrs. (rural) compared to 58.6 yrs. (urban) in 80405 (P < 0.01) and 59.6 yrs. to 60.2 yrs. in N9741 (P = 0.4). In 80405, pts in rural areas were less likely to be female (35% vs 43%, P < 0.01) black (6.6% vs 15.1%, P < 0.01), unmarried (51% vs 62%, P < 0.01), and to have private insurance (PI) (45% vs 50%, P = 0.03) when compared to pts in urban areas. In N9741, gender (P = 0.8) and PI (P = 0.3) distribution was similar; pts in rural areas were less likely to be black (1.4% vs 9.1%, P < 0.01). Rural vs urban pt PFS was no different in either trial. MOS was worse in pts in rural areas when compared to urban dwellers in 80405 (Table). OS outcomes stratified based on the use of cetuximab based regimen in 80405 showed worse outcomes for pts in rural compared to urban dwellers (21.9 vs 26.3 mo. HR: 1.22 (1.03-1.44), P = 0.02). Conclusions: MCRC pts from rural areas had a significantly worse mOS when compared to pts in urban areas in 80405. Furthermore, mOS with cetuximab based regimens was 4.4 months shorter in rural pts. The observed rural vs urban dweller mOS disparities in 80405 pts justifies additional research searching for causal factors and the necessity to identify actionable approaches in order to improve pt outcomes in rural areas. Support: U10CA180821, U10CA180882, U10CA180888, UG1CA180830; Pfizer, Sanofi, BMS, Genentech, https://acknowledgments.alliancefound.org . ClinicalTrials.gov Identifier: NCT00003594, NCT00265850. [Table: see text]