Eng, Cathy

TPS788 Background: MSLN is a desirable candidate for targeted therapy given its limited expression in normal tissues and its overexpression in several malignancies, including PANC, mesothelioma, non-small cell lung, and ovarian cancers (TCGA 2022). MSLN-targeted CAR T and T-cell receptor therapies have shown promising clinical activity; however, on-target, off-tumor toxicity, including fatal events, have occurred (1-3). Autologous logic-gated Tmod CAR T therapies address the challenges of on-target, off-tumor toxicity by combining 2 CARs: activating and blocking receptors. The activator recognizes a tumor-associated antigen present on the surface of both tumor and normal cells; the blocker prevents CAR T activity when it binds HLA-A*02, which is present in normal cells and often lost in tumor cells. Thus, in patients with tumor-associated HLA-A*02 LOH, the blocker prevents on-target, off-tumor toxicity on normal cells due to retained HLA-A*02 expression (4). HLA-A*02 LOH is observed in various solid tumors, including ~20% of PANC (5). Two autologous CAR T therapies are currently under investigation: A2B530, targeting carcinoembryonic antigen, in the EVEREST-1 trial, and A2B694, targeting MSLN, in the EVEREST-2 trial, described herein. A2B694 may provide a therapeutic window to treat patients with PANC and other MSLN-expressing solid tumors exhibiting HLA-A*02 LOH due to its unique discriminatory mechanism. Methods: EVEREST-2 (NCT06051695) is a first-in-human, phase 1/2, open-label, nonrandomized study to evaluate the safety and efficacy of A2B694 for recurrent unresectable, locally advanced, or metastatic cancers with MSLN expression, including PANC. Eligible patients must have exhausted options of potentially curative therapy and have recurrent disease. Enrollment to EVEREST-2 occurs through the prescreening study BASECAMP-1 (NCT04981119), in which patients with tumor-associated HLA-A*02 LOH are identified via next-generation sequencing (Tempus AI, Inc) and leukapheresis product is collected. A2B694 is manufactured from cryopreserved T cells when clinically appropriate for patients. The primary objective of phase 1 is to evaluate the safety and tolerability of A2B694 and identify the recommended phase 2 dose (RP2D). The dose-expansion phase will confirm RP2D and collect biomarker data to further characterize A2B694. Phase 2 will assess the primary endpoint overall response rate per RECIST v1.1 and secondary endpoints progression-free survival and overall survival. The first patient was dosed on April 24, 2024 and dose escalation is ongoing. 1. Beatty, et al. Gastroenterology . 2018. 2. Haas, et al. Mol Ther . 2023. 3. Hong, et al. ESMO 2021. Abstr 9590. 4. Hamburger, et al. Mol Immunol . 2020. 5. Hecht, et al. J Clin Oncol . 2022. Clinical trial information: NCT06051695 .

142 Background: Fruquintinib (F) is a highly selective, oral tyrosine kinase inhibitor of all 3 vascular endothelial growth factor receptors (VEGFRs -1, -2, -3) that is approved by the US FDA and in the EU, UK, and Japan for previously treated metastatic colorectal cancer (mCRC), regardless of biomarker status. FRESCO-2 (NCT04322539) met its primary endpoint demonstrating significantly improved overall survival (OS) with F + best supportive care (BSC) vs placebo (P) + BSC. This subgroup analysis assessed landmark survival of all FRESCO-2 patients (pts), and baseline (BL) characteristics and safety data of pts treated with F who had OS ≥10 months (mos) compared with the intent-to-treat (ITT) population (pop). Methods: Pts were randomized 2:1 to receive F 5 mg or matching P, by mouth, once daily, 3 weeks on, 1 week off, + BSC. Pts had received prior chemotherapy, anti-VEGF therapy and, if RAS wild type, anti-EGFR therapy; and had prior exposure to trifluridine/tipiracil (TAS-102) and/or regorafenib. The hazard ratio (HR) between the two treatment arms was calculated from a stratified Cox proportional hazard model with treatment group as the only covariate in the model. Results: In the ITT pop, OS was improved with F vs P (HR 0.66); OS rates (95% confidence intervals [CIs]) at 6 and 9 mos were 60.4% (55.9–64.9) vs 41.5% (35.0–48.0) and 41.1% (36.4–45.8) vs 28.2% (22.1–34.3), respectively. Progression-free survival (PFS) rates (95% CIs) at 6 and 9 mos were 23.8% (19.7–28.0) vs 1.1% (0–2.6) and 11.3% (8.1–14.6) vs 0.5% (0–1.6), respectively. Of 461 pts who received F, 113 (24.5%) had OS ≥10 mos (range 10.0–18.9) with a median duration of F treatment of 6.3 mos (range 0.7–19.1). Among pts receiving F, a higher proportion (≥10% difference) of pts with OS ≥10 mos had no liver metastases (mets) and an Eastern Cooperative Oncology Group performance status (ECOG PS) of 0 at BL compared with the ITT pop (Table). In pts with OS ≥10 mos, 61.9% experienced a grade ≥3 treatment-emergent adverse event compared with 62.7% in the ITT pop. Conclusions: Longer-term OS and PFS rates at 6 and 9 mos were higher with F vs P in the FRESCO-2 ITT pop. The data show a higher proportion of pts with OS ≥10 mos had an absence of liver mets and ECOG PS 0 at BL than the ITT pop. The safety profile of F in pts with OS ≥10 mos was consistent with the ITT pop. Clinical trial information: NCT04322539 . BL characteristics of pts treated with F with OS ≥10 mos vs ITT pop. BL characteristic Pts with OS ≥10 mos (n=113) ITT pop(n=461) ECOG PS (0 / 1), % 54.0 / 46.0 42.5 / 57.5 Median time since 1 st CRC diagnosis, mos 52.0 47.2 Primary tumor location at 1 st diagnosis (colon / rectum / both), % 51.3 / 35.4 / 13.3 60.5 / 31.0 / 8.5 Primary site at 1 st diagnosis (colon left / colon right), % 42.5 / 15.9 41.6 / 21.0 Liver mets, % 58.4 73.5 Median duration of mCRC, mos 42.7 37.9 Prior lines of therapy for mCRC (≤3 / >3), % 26.5 / 73.5 27.1 / 72.9 Prior TAS-102, % 46.9 52.1 Prior regorafenib, % 12.4 8.7

ASCO Guidelines provide recommendations with comprehensive review and analyses of the relevant literature for each recommendation, following the guideline development process as outlined in the ASCO Guidelines Methodology Manual . ASCO Guidelines follow the ASCO Conflict of Interest Policy for Clinical Practice Guidelines . Clinical Practice Guidelines and other guidance (“Guidance”) provided by ASCO is not a comprehensive or definitive guide to treatment options. It is intended for voluntary use by clinicians and should be used in conjunction with independent professional judgement. Guidance may not be applicable to all patients, interventions, diseases or stages of diseases. Guidance is based on review and analysis of relevant literature and is not intended as a statement of the standard-of-care. ASCO does not endorse third-party drugs, devices, services, or therapies and assumes no responsibility for any harm arising from or related to the use of this information. See complete disclaimer in Appendix 1 and 2 (online only). PURPOSE To provide evidence-based guidance for clinicians who treat patients with stage I-III anal cancer. METHODS A systematic review of the literature conducted by the Minnesota Evidence-based Practice Center provided the evidence base for this guideline. An ASCO Expert Panel reviewed this evidence and came to consensus on a set of evidence-based recommendations. RESULTS The systematic review contained three randomized controlled trials and three nonrandomized studies of interventions that were relevant to the guideline topic and informed the recommendations. RECOMMENDATIONS Mitomycin-C (MMC) with a fluoropyrimidine (fluorouracil [FU] or capecitabine) is recommended as the radiosensitizing component of chemoradiation (CRT) for anal cancer; the Expert Panel recognizes that capecitabine is often used as an orally administered alternative to FU and is currently being used in ongoing clinical trials. Cisplatin with FU is an additional chemotherapy combination that may be recommended as radiosensitizing chemotherapy. Because of the myelosuppression associated with MMC, the preferable regimen for patients with immunosuppression is cisplatin and FU. Cisplatin is not recommended for patients with renal dysfunction, significant neuropathy, or hearing loss, and there is no evidence to recommend substituting carboplatin for cisplatin. Dose and schedule options for recommended chemotherapy agents are included within the full text of the guideline. Routine induction chemotherapy before CRT and additional chemotherapy after CRT are not recommended for patients with localized anal cancer. Additional information is available at www.asco.org/gastrointestinal-cancer-guidelines .

3579 Background: Fruquintinib (F) is a highly selective, oral tyrosine kinase inhibitor of all 3 VEGF receptors. Based on FRESCO (NCT02314819) and FRESCO-2 (NCT04322539) data, F was approved by the US FDA for previously treatedmetastatic colorectal cancer (mCRC). Efficacy and safety of F + best supportive care (BSC) vs placebo (P) + BSC were analyzed according to prior treatment (tx) sequence using FRESCO and FRESCO-2 data. Methods: In FRESCO and FRESCO-2, patients (pts) were randomized 2:1 to receive F 5 mg or matching P, PO daily x 21 days every 28 days. In FRESCO, eligible pts had received ≥2 prior chemotherapy regimens and were permitted to have received prior anti-VEGF and/or anti-EGFR therapies, whereas in FRESCO-2, in addition to standard chemotherapies, anti-VEGF, and anti-EGFR therapies if indicated, prior exposure to trifluridine/tipiracil (TAS) and/or regorafenib (rego) was required. FRESCO-2 pts must have also received a BRAF inhibitor and/or immunotherapy, if indicated and available in their country. Results: In FRESCO (F n=278 vs P n=138), no pts had received rego and 16/416 pts (4%) had received TAS. InFRESCO-2, prior therapies were balanced between F vs P arms; pts had received prior TAS or rego in these sequences: prior TAS only (n=240 vs n=121); prior rego only (n=40 vs n=18); prior rego then TAS (n=84 vs n=45); prior TAS then rego (n=95 vs n=44). Improvements in OS and PFS were seen with F vs P regardless of prior tx sequence (Table), with similar magnitudes of benefit for OS (HRs 0.53–0.77) and PFS (HRs 0.25–0.37). F safety profile was consistent regardless of prior tx sequence (Table). Conclusions: F is effective in mCRC with a manageable safety profile regardless of prior TAS or rego tx and sequence. Improvement with F was similar for OS and PFS despite the number and sequence of prior regimens. F provides a new tx option for pts with previously treated mCRC regardless of prior TAS or rego exposure. Clinical trial information: NCT04322539 . [Table: see text]

Gastrointestinal (GI) cancers, including esophageal, gastroesophageal junction, gastric, duodenal and distal small bowel, biliary tract, pancreatic, colon, rectal, and anal cancer, comprise a heterogeneous group of malignancies that impose a significant global burden. Immunotherapy has transformed the treatment landscape for several GI cancers, offering some patients durable responses and prolonged survival. Specifically, immune checkpoint inhibitors (ICIs) directed against programmed cell death protein 1 (PD-1), either as monotherapies or in combination regimens, have gained tissue site-specific regulatory approvals for the treatment of metastatic disease and in the resectable setting. Indications for ICIs in GI cancer, however, have differing biomarker and histology requirements depending on the anatomic site of origin. Furthermore, ICIs are associated with unique toxicity profiles compared with other systemic treatments that have long been the mainstay for GI cancer, such as chemotherapy. With the goal of improving patient care by providing guidance to the oncology community, the Society for Immunotherapy of Cancer (SITC) convened a panel of experts to develop this clinical practice guideline on immunotherapy for the treatment of GI cancer. Drawing from published data and clinical experience, the expert panel developed evidence- and consensus-based recommendations for healthcare professionals using ICIs to treat GI cancers, with topics including biomarker testing, therapy selection, and patient education and quality of life considerations, among others.

3536 Background: Early-onset colorectal cancer (eoCRC, initial CRC diagnosis at age < 50 years) has been increasing in the past two decades especially in Western countries. This study evaluates somatic and germline profiles in eoCRC compared to average-onset CRC (aoCRC, initial CRC diagnosis at age ≥ 50 years). Methods: This is a retrospective, cross-sectional study utilizing data from de-identified records of colorectal cancer patients tested with the Tempus xT assay from 2017 to 2022. Briefly, the assay is a targeted panel that detects single nucleotide variants, insertions and/or deletions, and copy number variants in 598-648 genes, as well as chromosomal rearrangements in 22 genes with high sensitivity and specificity. Baseline characteristics and immunologic markers were compared between eoCRC and aoCRC by Wilcoxon Rank Sum or Chi-squared test (reporting p-values). Somatic and germline mutations were compared between two age groups with false discover rate adjustments (reporting q-values). Results: In this study, 2,379 eoCRC and 8,627 aoCRC patients were included, with the majority diagnosed with stage IV disease. Additionally, germline alterations were assessed on a subset of 6,311 patients with tumor/normal match testing (eoCRC = 1,413 and aoCRC = 4,898). Left-sided primaries were more common in eoCRC (85% left/rectum in eoCRC vs. 75% left/rectum in aoCRC (p < 0.001), and rates of microsatellite instability-high (MSI-H) or deficient mismatch repair (dMMR) were lower compared to aoCRC (4.2% vs. 6.8%, p < 0.001). eoCRC has a unique somatic mutation profile compared to aoCRC. A higher prevalence of germline mutations was observed in eoCRC overall (6.9% vs. 5%, p = 0.006); however, no statistically significant differences were observed in individual germline genes compared to aoCRC, likely due to relatively small numbers. Conclusions: eoCRC has a unique mutational profile and presence of germline mutations in 6.9% of eoCRC, indicating a potential role for universal germline testing in CRC. [Table: see text]

3572 Background: Early onset colorectal cancer (eoCRC: disease diagnosed < 50) has been increasing over the past 2 decades. Currently, standard treatment recommendations for eoCRC patients (pts) with metastatic disease does not differ from late-onset CRC (loCRC) pts although outcomes data in eoCRC pts is limited. Methods: Individual patient data on 5,761 treatment-naive metastatic eoCRC pts was pooled from 8 phase II and III randomized EGFRi studies (2000 - 2012) from the ARCAD mCRC database. The distribution of demographics, clinicopathological features, and biomarkers were summarized by age groups. Progression-free survival (PFS) was compared between age groups by stratified Cox models, adjusting for potential confounders. Predictive value of age group was evaluated by testing interaction effect between treatment and age variables based on a subset of trials with concurrent randomizations between regimens with and without EGFRi Results: eoCRC (n=756) were more evenly distributed between gender, had improved performance status (PS), increased likelihood of metastatic resection, and distant lymph node metastasis, but were less likely to have lung metastasis or KRAS mutation compared to loCRC (n=5,005, table 1). eoCRC and loCRC patients had similar distribution of primary tumor sidedness, primary resection, liver and/or peritoneal involvement, number of metastatic sites involved, and BRAF mutations (MT). No difference in PFS for eoCRC versus loCRC pts was noted (7.8 vs. 7.9 months [M], adjusted hazard ratio [HRadj], 1.02, 95% confidence interval [CI], 0.93-1.11). Among pts with KRAS wild type (WT) and left sided primary tumors, univariable analysis of EGFRi demonstrated improved mPFS in loCRC (9.9 vs 8.5M, HR = 0.74, p<0.001), but this benefit was not seen in eoCRC (8.3 vs 8.9 months, HR 1.20, p=0.36). The same pattern was observed upon multivariable analysis (Table). Conclusions: In our pooled analysis, EGFRi + chemotherapy significantly improved PFS in treatment-naïve loCRC patients but not in left sided, KRAS WT, eoCRC patients. Further validation in an independent cohort is warranted. [Table: see text]

101 Background: Colorectal cancer (CRC) incidence and mortality have decreased since the 1970s, but the incidence in young adults (20-49 years, named early-onset CRC, eoCRC) has been increasing. eoCRC patients with metastatic disease are treated with the same standard regimens as late-onset CRC (loCRC, age ≥ 50 years) although detailed response data for eoCRC are largely missing. Methods: Individual patient data on 7,604 subjects with metastatic eoCRC from 11 first line randomized bevacizumab studies between 2000 and 2012 in the ARCAD advanced colorectal cancer database were pooled. The distributions of demographics, clinicopathological features, biomarkers, and outcome data were summarized 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 was evaluated by testing interaction effect between treatment and age variables. Results: Female eoCRC are more commonly seen compared to loCRC (46.8% vs. 38.7%, p<0.0001). Patients with eoCRC (n=1,289) were significantly more likely to have had prior metastasectomy (17.5% vs. 13.5%, p=0.043) and lung metastatic disease (67% vs. 59.8%, p<0.001), but less likely to have distant lymph node metastatic disease (58.8 vs. 62.9%, p=0.036) or KRAS mutation (29.2% vs. 34.4%, p=0.042) compared to those with loCRC (n=6,315). eoCRC and loCRC patients had similar distributions according to PS, primary tumor sidedness, prior primary tumor resection, liver involvement, peritoneal involvement, number of metastatic sites, NRAS and BRAF. Age of disease onset was not a statistically significant prognostic factor for PFS in univariate and multivariate analysis (seen in table). Bevacizumab in addition to chemo improved PFS in eoCRC population (9.9 vs. 6.8 months, HR = 0.66, p<0.001), which was similar to the findings in loCRC population (9.4 vs. 7.3 months, HR= 0.73, p<0.001, interaction p=0.54). By multivariate analysis, a greater improvement in PFS was noted for the addition of bevacizumab in eoCRC relative to LoCRC patients (HR = 0.62 vs. HR = 0.82). Conclusions: Treatment naive eoCRC patients with metastatic disease derive similar benefit from bevacizumab relative to their average age counterparts.[Table: see text]

93 Background: Fruquintinib (F) is a highly selective, novel, oral tyrosine kinase inhibitor (TKI) of vascular endothelial growth factor receptors (VEGFR) -1, -2, and -3. The phase (Ph) 3 FRESCO study (NCT02314819) that investigated F (5mg daily, 3 weeks (wks) on 1 wk off) showed improved median overall survival in patients (pts) with metastatic colorectal cancer (mCRC) in third line and beyond when compared to placebo (9.3 vs. 6.6 months); hazard ratio 0.65 (P < 0.001) and led to its approval in China. Methods: This is an ongoing Ph 1/1b open-label, dose escalation/expansion study conducted in the US. Here we present the preliminary safety and antitumor efficacy data from pts with refractory mCRC in Cohort (Coh) B (progressed on all standard therapies including TAS-102 [TAS] and/or regorafenib [R]) and in Coh C (did not receive TAS or R). Results: As of data cutoff on 27 July 2021, 81 mCRC pts had been treated (41 in Coh B and 40 in Coh C); median age of 57 years (range: 34─77), Caucasian (81.5%), female (44.4%), and ECOG PS 1 (59.3%). In Coh B, the median number of prior therapies was 5 (range: 3-9), 8 pts (19.5%) received R, 19 (46.3%) received TAS and 14 (34.1%) received both R and TAS. In Coh C, the median number of prior therapies was 4 (range: 1-10). Five pts remain on treatment; reasons for treatment discontinuation included: 56 pts (69.1%) due to progressive disease or death, 8 pts (9.9%) due to adverse events (AE), and 12 pts (14.8%) due to withdrawal of consent or physician decision. The median duration of F treatment was 4.4 months (range: 0.7– 20.0) in Coh B and 3.7 months (range: 0.02-14.3) in Coh C. The most frequently reported AEs of any grade in Coh B were fatigue (53.7%), proteinuria (51.2%), and hypertension (HTN; 48.8%). In Coh C the most frequently reported AEs of any grade were HTN (75.0%), proteinuria (40.0%), and myalgia (32.5%). Hand-foot syndrome (HFS) was reported in 29.3% of Coh B pts and 22.5% of Coh C pts. The disease control rate [DCR] was 68.3% in Coh B (1 partial response [PR] and 27 stable disease [SD]) and 59.5% for the 37 patients with at least one post-baseline tumor assessment in Coh C (2 PRs and 20 SDs). Conclusions: F is generally well-tolerated in heavily-pretreated pts with refractory mCRC. Evidence of antitumor activity was observed in cohorts B and C. The multi-cohort dose expansion is ongoing. F is being further investigated in refractory mCRC in a global Ph 3 study (NCT04322539). Clinical trial information: NCT03251378.