Advanced Gastrointestinal Cancer Research Articles

Clinical impact of panel gene sequencing on therapy of advanced cancers of the digestive system: a retrospective, single center study

BackgroundPanel gene sequencing is an established diagnostic tool for precision oncology of solid tumors, but its utility for the treatment of cancers of the digestive system in clinical routine is less well documented.MethodsWe retrospectively identified patients with advanced or metastatic gastrointestinal, pancreaticobiliary or hepatic cancers who received panel gene sequencing at a tertiary university hospital from 2015 to 2022. For these cases, we determined the spectrum of genetic alterations, clinicopathological parameters and treatment courses. Assessment of actionability of genetic alterations was based on the OncoKB database, cancer-specific ESMO treatment guidelines, and recommendations of the local molecular tumor board.ResultsIn total, 155 patients received panel gene sequencing using either the Oncomine Focus (62 cases), Comprehensive (91 cases) or Childhood Cancer Research Assay (2 cases). The mean age of patients was 61 years (range 24–90) and 37% were female. Most patients suffered from either colorectal cancer (53%) or cholangiocellular carcinoma (19%). 327 genetic alterations were discovered in 123 tumor samples, with an average number of 2.1 alterations per tumor. The most frequently altered genes were TP53, KRAS and PIK3CA. Actionable gene alterations were detected in 13.5–56.8% of tumors, according to ESMO guidelines or the OncoKB database, respectively. Thirteen patients were treated with targeted therapies based on identified molecular alterations, with a median progression-free survival of 8.8 months.ConclusionsActionable genetic alterations are frequently detected by panel gene sequencing in patients with advanced cancers of the digestive tract, providing clinical benefit in selected cases. However, for the majority of identified actionable alterations, sufficient clinical evidence for targeted treatments is still lacking.

Prognostic value of pretreatment neutrophil-to-lymphocyte ratio in advanced gastrointestinal cancer immunotherapy: evidence from published studies and a Chinese single center cohort

BackgroundIdentification of prognostic biomarkers for outcomes in gastrointestinal (GI) cancer with immunotherapy is important. This study investigated the relationship between the prognostic biomarker, pretreatment neutrophil-to-lymphocyte ratio (preNLR), and immunotherapeutic outcomes in patients with advanced GI cancer.MethodsWe searched the PubMed, Embase, and Cochrane Library databases for studies reporting predictive values for preNLR in patients with advanced GI cancer treated with immune checkpoint inhibitor (ICI). The primary outcomes considered were progression-free survival (PFS) and overall survival (OS). Hazard ratios (HRs) with 95% confidence intervals (CIs) for PFS and OS were pooled using a random effects model. We then validated the results observed in an in-house cohort of patients treated with ICIs for advanced GI cancers. Other prognostic factors for PFS and OS were explored using Cox proportional hazard analyses.ResultsOverall, 27 observational studies involving 3,610 patients with advanced GI cancer were included. Patients with higher preNLR were associated with poorer PFS (HR 1.70, 95% CI 1.50–1.92) and OS (HR 2.35, 95% CI 1.82–3.03) with ICI treatment. Subgroup analyses based on NLR cut-off value, research center, sample size, and ICI drugs used were consistent with the primary results. A retrospective analysis of the in-house patient cohort validated these results (PFS: HR 3.173, 95% CI 2.314–4.351; OS: HR 3.004, 95% CI 1.837–4.912). Multivariable Cox regression analysis of 174 patients showed that higher preNLR and negative programmed death ligand-1 (PD-L1) expression were independently, significantly, and unfavorably associated with PFS and OS.ConclusionPreNLR might be an effective prognostic biomarker for patients with advanced GI cancer treated with ICIs.

68Ga-NC-BCH Whole-Body PET Imaging Rapidly Targets Claudin18.2 in Lesions in Gastrointestinal Cancer Patients.

68Ga-labeled nanobody (68Ga-NC-BCH) is a single-domain antibody-based PET imaging agent. We conducted a first-in-humans study of 68Ga-NC-BCH for PET to determine its invivo biodistribution, metabolism, radiation dosimetry, safety, and potential for quantifying claudin-18 isoform 2 (CLDN18.2) expression in gastrointestinal cancer patients. Methods: Initially, we synthesized the probe 68Ga-NC-BCH and performed preclinical evaluations on human gastric adenocarcinoma cell lines and xenograft mouse models. Next, we performed a translational study with a pilot cohort of patients with advanced gastrointestinal cancer on a total-body PET/CT scanner. Radiopharmaceutical biodistribution, radiation dosimetry, and the relationship between tumor uptake and CLDN18.2 expression were evaluated. Results: 68Ga-NC-BCH was stably prepared and demonstrated good radiochemical properties. According to preclinical evaluation,68Ga-NC-BCH exhibited rapid blood clearance, high affinity for CLDN18.2, and high specific uptake in CLDN18.2-positive cells and xenograft mouse models. 68Ga-NC-BCH displayed high uptake in the stomach and kidney and slight uptake in the pancreas. Compared with 18F-FDG, 68Ga-NC-BCH showed significant differences in uptake in lesions with different levels of CLDN18.2 expression. Conclusion: A clear correlation was detected between PET SUV and CLDN18.2 expression, suggesting that 68Ga-NC-BCH PET could be used as a companion diagnostic tool for optimizing treatments that target CLDN18.2 in tumors.

[Malnutrition in advanced gastrointestinal cancer patients and nutritional support therapy].

The advancement of comprehensive treatment has allowed an increasing number of patients with gastrointestinal tumor to achieve long-term survival. In current clinical practice, there is a growing population of patients with advanced gastrointestinal tumor. Due to various factors, such as tumor burden, treatments including chemotherapy and radiation therapy, as well as underlying diseases, patients with advanced gastrointestinal tumor often experience malnutrition, which negatively impacts their clinical outcomes. The mechanism of malnutrition in patients with advanced gastrointestinal tumor is complex, and conventional nutritional support therapy has shown limited effectiveness. With the continuous progress in the concept and technique of nutritional support therapy, the diversification of treatment strategies, and the strengthening of multidisciplinary collaboration, the nutritional management for patients with advanced gastrointestinal tumor tends to be standardized and rational, leading to effective improvement in patients' nutritional status and clinical outcomes. Based on the latest evidence-based medicine, combined with the author's practical experience and insights, this article aims to explore nutritional support therapy for patients with advanced gastrointestinal tumor.

Abstract 6298: The value of routine trastuzumab-related cardiac toxicity monitoring in gastrointestinal cancers

Abstract Background: It is a common practice to monitor trastuzumab-related cardiac toxicity (TRCT) using left ventricular ejection fraction (LVEF) in patients who receive trastuzumab-containing therapy for human epidermal growth factor receptor 2 (HER2)-positive cancers. However, this monitoring approach does not appear cost effective in patients with HER2-positive gastrointestinal (GI) cancers given poor overall survival (OS). Here, we aim to examine the incidence of clinically significant TRCT in this target population. Methods: This is a retrospective cohort study of patients with advanced HER2-positive GI cancers who received trastuzumab-containing therapies (trastuzumab +/- pertuzumab, chemotherapy +/- immunotherapy + trastuzumab, trastuzumab deruxtecan) between 2011 and 2023. HER2 status was determined by immunohistochemistry, fluorescent in situ hybridization, and/or next generation sequencing. LVEF was estimated by serial transthoracic echocardiograms (TTE). Continuous variables were summarized as median and interquartile range (IQR). Paired Wilcoxon signed rank test was used to compare serial LVEF. OS was estimated using Kaplan-Meier method. Results: A total of 243 patients were included in this study with a median age of 64 (IQR: 55-70) years. 139 (57%) patients had esophageal or GEJ adenocarcinoma; 45 (19%) patients had gastric cancer; 37 (15%) patients had colorectal cancer; and the rest had other GI cancers. Median follow-up time was 18.6 (IQR: 9.2-36) months. Median OS from cancer diagnosis and the first dose of trastuzumab-containing therapy were 24.1 (95%CI: 20.2-30.2) and 11.7 (95%CI: 10.4-15.6) months, respectively. Patients received a median of 13 cycles of trastuzumab-containing therapy for a median duration of 4.1 (IQR: 1.4-10.1) months. The median number of TTE each patient had throughout therapy was 2 (IQR: 1-4). Median baseline LVEF was 61% (IQR: 56-65%) which was significantly higher (p<0.001) than the median lowest LVEF of 58% (IQR: 53-62%) during therapy, but not different (p=0.14) from the most recent median LVEF of 60% (IQR: 56-64%) after discontinuation of trastuzumab. Among 176 patients with serial LVEF data, 16 (9%) had > 10% LVEF drop; 7 (44%) of these 16 patients had LVEF recovery. None of the cardiovascular risk factors prior to trastuzumab treatment including hypertension, diabetes, hyperlipidemia, peripheral arterial disease, coronary artery disease, and stroke were significantly associated with the development of TRCT. Conclusion: The incidence of clinically significant LVEF drop appears low in patients with advanced GI cancers as post-treatment LVEF recovery to baseline was observed at the population level. The value of using TTE to monitor TRCT in these patients with short OS should be further assessed in the perspective of cost effectiveness. Citation Format: Samual R. Kosydar, Matteo Castrichini, Mojun Zhu, Hao Xie. The value of routine trastuzumab-related cardiac toxicity monitoring in gastrointestinal cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6298.

Abstract 6469: The association of mismatch repair gene alterations with elevated tumor mutational burden in microsatellite stable gastrointestinal cancers

Abstract Background: Benefit from single-agent immune checkpoint inhibitor has been observed in 5-10% of the patients with microsatellite stable (MSS) gastrointestinal (GI) cancers. However, a reliable predictive marker to immune checkpoint inhibitor has not been discovered in this patient population. We sought to assess the incidence of mismatch repair (MMR) gene alterations and their association with tumor mutational burden (TMB) in MSS GI cancers. Methods: This is a retrospective cohort study of patients with advanced GI cancer who had molecular profiling of the tumor using either Guardant360 blood-based or Tempus tissue next generation sequencing (NGS) platforms between 2020 and 2023. We assessed four MMR genes including MLH1, MSH2, MSH6 and PMS2 for alterations. Continuous variables were summarized as median and interquartile range (IQR) and compared using Mann-Whitney test. Categorical variables were summarized as counts and proportions and compared using Fisher’s exact test. Results: A total of 2920 patients with Guardant360 were included with a median age of 65 (IQR: 56-73) years. 870 (30%) patients had pancreas cancer; 846 (29%) patients had colorectal cancer; 688 (24%) patients had biliary tract cancers; and the rest had other GI cancers. Among patients evaluable for microsatellite instability (MSI) status, 58 patients (2%) had MSI-high GI cancers, 31 (53%) of whom had MMR gene alterations. 2445 (98%) patients had MSS GI cancers, 130 (5.3%) of whom had MMR gene alterations. Patients with MSS GI cancers bearing MMR gene alterations had a median age of 70 (IQR: 62-75) years, significantly older than those without MMR gene alterations (p<0.001). In addition, patients with MMR gene alterations had significantly higher median blood TMB of 11 (IQR: 7.4-16) mut/Mb compared to 7.7 (IQR: 4.8-11) mut/Mb in patients without MMR gene alterations. In MSS GI cancers, MMR gene alterations are more commonly associated with the presence of alterations in APC (p=0.03), TP53 (p=0.01), CTNNB1 (p<0.001) and SMAD4 (p=0.01). 1453 patients with GI cancer and Tempus tissue NGS data were included as a validation cohort. They had comparable demographics with the Guardant360 cohort. 14 (1.6%) of 896 patients with MSS GI cancers had MMR gene alterations, significantly fewer (p<0.001) than those found in the Guardant360 cohort. Patients with MMR gene alterations and wild type POLE had significantly higher (p=0.001) median TMB of 9.8 (IQR: 4.8-14) mut/Mb compared to 4.7 (IQR: 3.2-6.3) mut/Mb in patients without MMR gene alterations. Conclusions: MMR gene alterations can be identified by clinical NGS platforms in a small proportion of patients with MSS GI cancers. They are associated with elevated TMB, which may suggest a hypermutated profile serving as a basis for potential role of immune checkpoint inhibitor in MSS GI cancers. Citation Format: Conor D. O'Donnell, Mojun Zhu, Hao Xie. The association of mismatch repair gene alterations with elevated tumor mutational burden in microsatellite stable gastrointestinal cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6469.

Abstract 7493: Real-time monitoring of CTC number, biomarker expression, and kinetics as prognostic and predictive markers in patients with GI malignancies

Abstract Background: Most of the utility in the clinic regarding liquid biopsies has been around circulating tumor DNA (ctDNA). ctDNA analysis provides valuable insight into mutational burden and therapeutic targets, but the speed and cost of analysis are prohibitive especially when it comes to serial testing. Using a cohort of patients with advanced or metastatic gastrointestinal (GI) cancers, we herein show the feasibility of using circulating tumor cell (CTC) enumeration, biomarker analysis, and kinetics as complementary to or as an alternative to ctDNA testing. Methods: Using the RareCyte platform, nucleated cells from blood were collected, spread on slides, stained, and imaged with CyteFinder® for CTC identification (CK/EpCAM+, CD45-) and quantification of biomarkers (PD-L1/HER2 or Ki67/EGFR). CTC enumeration (CLIA-accredited CTC test) and biomarker status for each patient were tracked over time and compared with ctDNA mutational analysis and tumor burden. Results: CTCs were detected in 60/70 samples (86%) and in 36/38 unique patients (95%). On average, more CTCs were detected in baseline samples from colorectal cancer patients compared to other subtypes (Table 1). Moreover, multiple patients showed pronounced changes in CTC number that correlated with treatment response, as well as strong correlation between CTC and tissue biomarker expression e.g. HER2. Rapid decline and/or CTC clearance was seen as early as a few days into starting effective systemic therapy. The average turnaround time for CTC testing was 5-7 days. Table 1. CTC values in initial baseline blood draw sample Gastrointestinal cancer subtype # of patients Average # of CTCs per 7.5mL blood Median # of CTCs per 7.5mL blood Minimum # of CTCs per 7.5mL blood Maximum # of CTCs per 7.5mL blood Colorectal carcinoma 27 84 3 0 1378 Cholangiocarcinoma 3 8 3 1 23 Pancreatic cancer 3 2 2 0 3 Hepatocellular carcinoma 2 4 5 0 10 Gallbladder cancer 1 6 6 3 8 Appendix cancer 1 2 2 1 3 Anal cancer 1 0 0 0 0 Conclusions: Our study emphasizes that real-time monitoring of CTCs is complementary to traditional tumor burden monitoring via imaging and ctDNA analysis. CTCs offer multiple unique advantages vs ctDNA including early response assessment within days of initiating therapy, a substantial decrease in cost of serial testing, and the ability to assess clinically relevant cell surface protein biomarkers e.g. HER2 and PD-L1. Citation Format: Erin G. Bayer, Brock M. Bartels, Rachel N. Ponting, Areeb Lutfi, Maaz K. Afghan, Arturo B. Ramirez, Pashtoon M. Kasi. Real-time monitoring of CTC number, biomarker expression, and kinetics as prognostic and predictive markers in patients with GI malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7493.

Abstract 1326: Pre-clinical development of ARB011: A CDH17 targeting allogeneic nonviral RNA-based “Flash” CAR-NK therapy for gastrointestinal cancer

Abstract Background: Treatment for advanced gastrointestinal (GI) cancers has remained challenging, therefore, novel immunotherapies using chimeric antigen receptor (CAR)-T cells are being developed as a new hope for the patients. However, despite the clinical successes in hematologic malignancies, the overall safety and efficacy against solid tumors of CAR-T cells have yet to be established, and the manufacturing of autologous CAR-T cells requires lengthy cell expansion and viral transduction processes. In view of these technical challenges, we have developed ARB011, an RNA-based allogeneic CAR-NK therapy targeting GI cancers expressing cadherin-17 (CDH17), a promising therapeutic target with its overexpression associated with poor prognosis in patients with GI cancers. The use of allogeneic NK cells would mitigate the risk of graft-versus-host disease. Moreover, engineering NK cells with nonviral CAR-encoding mRNA would provide a rapid large-scale manufacturing platform with minimal risk of abnormal genetic alteration mediated by viral integration. Methods: To generate the ARB011 CAR-NK cells, ex vivo expanded human peripheral blood NK (Magicell-NK, Medigen, Taiwan) cells were electroporated with mRNA encoding a humanized anti-CDH17 scFv fused with transactivation domains. Flow cytometry, in vitro cytotoxicity assay, and cytokine release assay were performed to evaluate the expression and functionality of ARB011. To examine the developability of ARB011 as an off-the-shelf cell product, cryopreservation and large-scale electroporation were also studied. Results: Flow cytometry analysis revealed efficient electroporation with a high level of CDH17 CAR expression (>80%) and optimal CAR-NK cell viability (60%-80%). Following electroporation, cytotoxicity of ARB011 was tested against gastric (AGS and NCI-N87), colorectal (DLD-1 and T84), and liver (MHCC-97H) cancer cells by co-culturing at 1:1 and 2:1 effector/target ratio for 12-24h. ARB011 showed significant cytotoxicity against CDH17+ but not CDH17- cancer cells. The CDH17-sepcific cytotoxicity was accompanied with elevated levels of CD107a or LAMP-1 expression on CAR-NK cells and IFN-γ and TNF-α releases. Interestingly, cryopreserved ARB011 maintained optimal cell viability, CAR expression, and potent CDH17 target-specific cytolytic activity. Lastly, large-scale electroporation showed the establishment of up-scaling process of ARB011 production for clinical application. Conclusions: Overall, the findings suggest that ARB011 could be a novel off-the-shelf, CAR-NK therapy that warrants further studies in animal models and in clinical trials. Citation Format: Jaydeep Roy, Nga Tin Lin, Kronos Chow, Chih Ya Yang, James C.L. Lin, John M. Luk, Kwong F. Wong. Pre-clinical development of ARB011: A CDH17 targeting allogeneic nonviral RNA-based “Flash” CAR-NK therapy for gastrointestinal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1326.

Abstract 3212: Development of a Trop2/CD3 bispecific antibody with modulated Trop2 binding affinity as a novel immunotherapy for advanced gastrointestinal cancer treatment

Abstract Trophoblast cell surface antigen 2 (Trop2) is considered as a potential therapeutic target because its over-expression in tumors is found to be associated with poor prognosis of patients with different cancers. Trop2-directed antibody-drug conjugates have been approved for the treatment of solid tumors, however, the expression of Trop2 in a broad range of epithelial tissues, even in low expression, would limit their clinical benefits. The present work generated a novel Trop2/CD3 bispecific antibody with its binding affinity towards Trop2 being well-modulated to mitigate the chance of on-target off-tumor effect. By linking a humanized anti-Trop2 monoclonal antibody with a CD3-binding scFv, a Trop2/CD3 bispecific antibody was produced. In order to adjust the bispecific antibody's affinity to the tumor target, ProABC-2 was used for in-silico paratope prediction (Ambrosetti F et al., 2020). A complementarity-determining residue (CDR) variant was produced and its binding to Trop2 antigen was analyzed using biolayer interferometry. The binding of both wild type (WT) and variant antibodies to Trop2-positive cancer cells, the activation of T cells upon target engagement and the redirection of T cell-mediated killing on cancer cells expressing high level of Trop2 were examined. The binding affinity of CDR variant to Trop2-expressing tumor cells was significantly reduced, which led to a slower induction of cytokines and T-cell proliferation, less acute T-cell activation, and a milder cytotoxic effect. This allowed the bispecific antibody to have a higher level of safety by restricting the cytotoxicity only to cancer cells that expressed high level of Trop2. Our novel Trop2/CD3 bispecific antibody not only showed potent anti-tumor activity, but also demonstrated a lower risk of on-target off-tumor toxicity. Monkey toxicity and other IND-enabling studies are beginning to further bring the drug candidate into clinical trial. Table showing EC50 values of Trop2/CD3 bispecific WT and CDR variant antibodies in different assays WT CDR variant Binding affinity (M) Trop2 4.62E-11 2.14E-10 Cytotoxicity (M) AsPC1 (low Trop2 level) 1.24E-11 No killing effect SW480 (medium Trop2 level) 1.25E-12 2.25E-11 NCI-H596 (high Trop2 level) 5.65E-12 5.89E-10 Receptor occupancy (%) Trop2 0.65 2.75 CD3 0.08 5.83 Cytokine induction (M) IL-2 4.82E-11 5.42E-11 IFNγ 6.46E-13 2.59E-11 T cell activation (M) CD25+ marker 2.02E-12 2.39E-10 CD69+ marker 3.81E-13 7.40E-11 T cell proliferation (M) Ki-67 marker 3.54E-12 8.80E-11 Citation Format: Chui Yee O, Po Yee Wong, Kronos Chow, Kwan Wa Wong, Dennis Wong, John Moon Luk, Kwong Fai Wong. Development of a Trop2/CD3 bispecific antibody with modulated Trop2 binding affinity as a novel immunotherapy for advanced gastrointestinal cancer treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3212.

Abstract 3213: A novel CDH17/PD-1 bispecific antibody for treatment of advanced gastrointestinal cancers

Abstract Targeting immune checkpoints like programmed death receptor 1 (PD-1) with monoclonal antibodies has achieved durable responses in a range of cancers, however, immune-related adverse events may occur in a subset of patients. As such, we developed a bispecific antibody targeting cadherin-17 (CDH17) and PD-1 with a hope to rejuvenate specifically the exhausted T cells within tumor microenvironment. In healthy individuals, CDH17 is expressed at a restricted level in intestinal epithelial junction that is not accessible to biologics, however, in gastrointestinal cancers, CDH17 is overexpressed and can be targeted by antibodies. Our new CDH17/PD-1 bispecific antibody would reactivate anti-tumor immunity with reduced risk of on-target off-tumor toxicity. Different bispecific antibody formats were designed, cloned, and expressed. Strong binders were first identified using CDH17 and PD-1 ELISA. The binding affinities to CDH17 and PD-1 of the selected candidate were examined using biolayer interferometry. The effect of these bispecific antibodies on blocking PD-1/PD-L1 axis in T cells was demonstrated in a cell-based reporter assay. T-cell mediated killing on CDH17-positive GI cancer cells and induction of T cell activation markers upon antibody treatment were also studied. A total of 7 CDH17/PD-1 bispecific antibodies of different formats were screened. Of these candidates, one, named ARB204, was selected because of its potent binding to both antigens in ELISA (i.e., EC50 values: CDH17, 1.6nM; PD-1, 0.4nM) and biolayer interferometry (i.e., KD values: CDH17, 2.4E-09M; PD-1, 6.02E-11M). ARB204 blocked PD-1/PD-L1 axis in the reporter assay with EC50 value 4.4nM. Notably, ARB204 redirected T cells to eradicate CDH17-positive pancreatic AsPC1 cells with an EC50 value of 3.5nM. No cytotoxicity against CDH17-negative cancer cells were seen. ARB204 effectively bound CDH17 on GI cancer cells and PD-1 on T cells. This bispecific design allowed selective T-cell mediated killing on cancer cells expressing CDH17, mitigating the risk of off-tumor toxicity. ARB204 warrants further studies on its immune checkpoint inhibition in animal models. Citation Format: Kwan Wa Wong, Po Yee Wong, Kronos Chow, Chui Yee O, Dennis Wong, John Moon Luk, Kwong Fai Wong. A novel CDH17/PD-1 bispecific antibody for treatment of advanced gastrointestinal cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3213.

Methylthioadenosine Phosphorylase Genomic Loss in Advanced Gastrointestinal Cancers

Abstract Background One of the most common sporadic homozygous deletions in cancers is 9p21 loss, which includes the genes methylthioadenosine phosphorylase (MTAP), CDKN2A, and CDKN2B, and has been correlated with worsened outcomes and immunotherapy resistance. MTAP-loss is a developing drug target through synthetic lethality with MAT2A and PMRT5 inhibitors. The purpose of this study is to investigate the prevalence and genomic landscape of MTAP-loss in advanced gastrointestinal (GI) tumors and investigate its role as a prognostic biomarker. Materials and Methods We performed next-generation sequencing and comparative genomic and clinical analysis on an extensive cohort of 64 860 tumors comprising 5 GI cancers. We compared the clinical outcomes of patients with GI cancer harboring MTAP-loss and MTAP-intact tumors in a retrospective study. Results The prevalence of MTAP-loss in GI cancers is 8.30%. MTAP-loss was most prevalent in pancreatic ductal adenocarcinoma (PDAC) at 21.7% and least in colorectal carcinoma (CRC) at 1.1%. MTAP-loss tumors were more prevalent in East Asian patients with PDAC (4.4% vs 3.2%, P = .005) or intrahepatic cholangiocarcinoma (IHCC; 6.4% vs 4.3%, P = .036). Significant differences in the prevalence of potentially targetable genomic alterations (ATM, BRAF, BRCA2, ERBB2, IDH1, PIK3CA, and PTEN) were observed in MTAP-loss tumors and varied according to tumor type. MTAP-loss PDAC, IHCC, and CRC had a lower prevalence of microsatellite instability or elevated tumor mutational burden. Positive PD-L1 tumor cell expression was less frequent among MTAP-loss versus MTAP-intact IHCC tumors (23.2% vs 31.2%, P = .017). Conclusion In GI cancers, MTAP-loss occurs as part of 9p21 loss and has an overall prevalence of 8%. MTAP-loss occurs in 22% of PDAC, 15% of IHCC, 8.7% of gastroesophageal adenocarcinoma, 2.4% of hepatocellular carcinoma, and 1.1% of CRC and is not mutually exclusive with other targetable mutations.

PD-1 inhibition combined with intensity-modulated radiotherapy, to better serve patients with retroperitoneal lymph node metastases from gastrointestinal cancer.

Gastrointestinal (GI) cancer is the most frequent kind of cancer to involve the retroperitoneal lymph nodes (RPLNs). Radiotherapy (RT) is common treatment of RPLN metastases in patients with GI cancer, while RT is local. Meanwhile, most patients have extra-retroperitoneal metastases. Immunotherapy plus RT have showed effective in advanced non-small cell lung cancer. However, whether the combination therapy is effective on GI cancer with RPLN metastases. In our study, we would estimate the effect of programmed death-1 (PD-1) inhibition in association with intensity modulated radiation therapy (IMRT). Metastatic GI cancer patients with RPLN who were treated at a single institution were retrospectively evaluated from October 2016 to April 2023, who all had measurable lesion and received any therapy of PD-1 inhibitors alone, IMRT alone or PD-1 inhibitors plus IMRT. The follow-ups were assessed by abdominal computed tomography (CT) every 2 or 3 months to progression, dose-limiting toxicity or death. Among the 98 patients, 46 were treated by PD-1 inhibitors combined with IMRT, 26 were by PD-1 inhibitors only and 26 were by IMRT only. Of those, the median age 62 years (range, 25-84 years). Median progression-free survival (PFS) was 7.5 months and median overall survival (OS) was 10.8 months across the 3 therapy groups. Univariate analysis (UVA) indicated that therapy method (P=0.032) and tumor response (P=0.035) were significantly related to PFS. In the PD-1 inhibitors plus IMRT group, 1 patient (2.2%) achieved complete response (CR), 30 (65.2%) had partial remission, and 14 (30.4%) had stable disease. There was no case with CR by IMRT or PD-1 inhibitors alone. Objective response rate (67.4%) and disease control rate (97.8%) were higher in the PD-1 inhibitors combined with IMRT group. In the PD-1 inhibitors plus IMRT and PD-1 inhibitors alone groups, hepatitis B virus (HBV)-positive patients had better OS (P=0.041) on UVA. Meanwhile, in the PD-1 inhibitors plus IMRT group, we observed superior PFS (P=0.041) and OS (P=0.049) in HBV-positive patients on UVA. PD-1 inhibitors plus IMRT may be a better method for advanced GI cancer patients with RPLN metastases. HBV-positive patients can benefit from either PD-1 inhibitors alone or in combination with IMRT.

Nivolumab in patients (pts) with advanced gastrointestinal (GI) cancers with high plasma tumor mutational burden (pTMB): Results from a SCRUM-Japan GOZILA phase II trial.

98 Background: TMB is a biomarker for immune checkpoint inhibitors (ICIs). Analysis of circulating tumor DNA (ctDNA) has the potential to non-invasively identify pts likely to benefit from ICIs by assessing pTMB. We conducted a phase II basket trial as part of the SCRUM-Japan GOZILA umbrella/basket trial to evaluate the efficacy and safety of nivolumab monotherapy in pts with advanced GI cancers with high pTMB. Methods: Eligibility criteria included histologically confirmed unresectable or recurrent GI cancers; ECOG PS of 0 or 1; refractory or intolerant to the standard therapies; and high pTMB identified by Guardant360 CDx, a 74-gene ctDNA assay. Pts received intravenous nivolumab monotherapy of 360 mg every 3 weeks until progressive disease. The primary endpoint was objective response rate (ORR) per investigator assessment. The pTMB score was calculated by adjustment of mutation count by tumor fraction, and initial pTMB thresholds were determined based on previously reported ORR for ICI treatment for each GI cancer in the cohort. The cohort 2 proceeded only for esophageal cancer, and an ultra-high TMB cohort was created to include pts in the top 2% for pTMB scores. Results: Fifty-one pts with high pTMB in the cohort 1/2 (n=32) and the ultra-high TMB cohort (n=19) were enrolled. The median duration of follow-up was 7.5 months (range, 0.9–51.3). Deficient mismatch repair (dMMR) or high microsatellite instability (MSI-H) was observed in 1 pt in cohort 1/2 and 2 in ultra-high TMB cohort. The ORR was 12.5% and 21.1%, with median duration of response of 14.0 months and not reached, respectively. In an exploratory analysis of the overall population, pts with esophageal cancer had the highest ORR of 33.3% (4/12), followed by pancreatic (1/6, 16.7%) and colorectal cancer (3/27, 11.1%). Of 2 pts with proficient MMR/non-MSI-H colorectal cancer who had a response, 1 had a POLE mutation. Pts with response tended to have higher pTMB score (median, 26 vs. 8). dMMR/MSI-H (HR=0.16; 95% CI, 0.02–1.18), PD-L1 CPS ≥1 (HR=0.55; 95% CI, 0.29–1.01), and absence of liver metastasis (HR=0.36; 95% CI, 1.48–5.14) were significantly associated with longer progression-free survival. Treatment-related grade 3–4 adverse events occurred in 3 pts (9%) in the cohort 1/2 and 3 (16%) in the ultra-high TMB cohort, with no treatment death in either cohort. Conclusions: Nivolumab demonstrated antitumor activity in pretreated pts with advanced GI cancer and high pTMB. These results suggest that the use of pTMB potentially identify patients who may benefit from ICI treatment. Clinical trial information: UMIN000033182 .

Efficacy of biomarker-matched therapy in clinical trials for advanced gastrointestinal cancers: A pooled analysis of SCRUM-Japan studies.

753 Background: We conduct the SCRUM-Japan MONSTAR-SCREEN, a nationwide molecular profiling project to facilitate the enrollment of patients with advanced solid tumors into matched clinical trials based on identified biomarkers. Here, we investigated clinical outcomes of patients with gastrointestinal cancers in this project. Methods: The SCRUM-Japan GI-SCREEN was launched for gastrointestinal cancers in 2015, followed by GOZILA, MONSTAR-SCREEN-1, and MONSTAR-SCREEN-2 for advanced solid tumors. The used profiling assay for genomic alterations was Oncomine Comprehensive Assay for tumor tissue in GI-SCREEN, Guardant360 for plasma in GOZILA, FoundationOne CDx for tissue and FoundationOne Liquid CDx for plasma in MONSTAR-SCREEN-1, and CARIS MI Profile for tissue in MONSTAR-SCREEN-2. Patients were treated in clinical trials or practice based on identified biomarkers. We analyzed data from patients with gastrointestinal cancers in this project. Results: Of 11,408 patients enrolled in our project as of May 22, 2023, 555 (5.0%) were enrolled in matched clinical trials based on identified biomarkers. The major cancer types that had matched clinical trials included colorectal (63.2%), biliary tract (12.4%), gastric (n=9.2%), esophageal (n=6.5%), and pancreatic cancer (n=4.7%). The objective response rate (ORR), median progression-free survival, and median overall survival (OS) for patients in matched trials were 27.8% (95% CI, 24.0% to 31.9%), 3.0 months (95% CI, 2.8 to 3.7 months), and 14.4 months (95% CI, 13.0 to 16.1). The major treatment lines in which investigational drugs were administered were third (24.6%) and fourth (16.0%) line. Evaluating by each drug target given to at least 20 patients, therapies targeting HER2 had the highest ORR of 46%, followed by PD-1/PD-L1 (33%), BRAF (30%), and MEK (28%). Antibody-drug conjugates demonstrated the highest ORR with 48.8%, followed by monoclonal antibodies at 37.7% and small molecule inhibitors at 23.0%. Overall, patients who received matched therapy in clinical trials or practice had significantly longer OS than those who did not (hazard ratio, 0.76; 95% CI 0.69 to 0.84; P <0.01). Conclusions: Our nationwide molecular profiling project has facilitated the enrollment of patients with advanced gastrointestinal cancers in clinical trials. Furthermore, it demonstrated a survival benefit by providing patients matching targeted therapy.

Real-world analysis of patients with advanced gastrointestinal (GI) cancers harboring inactivating TSC1 and TSC2 alterations using the Foundation Medicine genomic database.

558 Background: Genomic profiling of GI tumors can identify potentially actionable genetic alterations, ultimately leading to better outcomes in patients who currently have few treatment options. In exploratory biomarker analyses of patients with perivascular epithelioid cell tumors treated with the mTOR inhibitor nab-sirolimus (AMPECT, NCT02494570), those with inactivating alterations in the tumor suppressor genes TSC1 or TSC2 (critical negative regulators of mTOR activity) had confirmed responses (8/9 patients with inactivating TSC2 alterations and 1/5 patients with inactivating TSC1 alterations). PRECISION 1, a currently enrolling tumor-agnostic study, will evaluate nab-sirolimus in patients with TSC1 or TSC2 alterations. To enumerate the frequency of these alterations in GI cancers, we analyzed data from a real-world genomic database. Methods: Next-generation sequencing (NGS) data from Foundation Medicine’s genomic database of patients with advanced cancer were analyzed using the FoundationInsights web-based platform to identify patients with GI cancers who had inactivating TSC1 or TSC2 alterations (short variants [base substitutions, insertions and deletions], rearrangements, and copy number deletions). Tumor mutational burden (TMB), microsatellite instability status and other mutations were also characterized in this group of patients. Results: As of 29 March 2022, tumor tissue NGS data were available for 5816 patients with GI cancers bearing alterations in TSC1 or TSC2. Of these, 1642 patients had at least one inactivating alteration. The GI tumor types that most frequently expressed inactivating alterations in TSC1 or TSC2 were hepatocellular carcinoma (alterations in 6.5%); colorectal adenocarcinoma (1.7%); gastrointestinal stromal tumors (1.7%); and cholangiocarcinoma (1.6%). Of all 1642 patients, 688 were female, and most (74%) were 51–80 years of age when the sample was obtained. Of patients with inactivating TSC1 and TSC2 alterations, 37.6% were in TSC1 and 62.9% were in TSC2 and included short variants (31.3% and 48.4%), rearrangements (2.7% and 6.6%), and copy number deletions (3.5% and 7.4%), respectively. TMB was low (<6 mutations/megabase) in 58% of patients, and most patients had microsatellite stable (MSS; 71.3%) tumors. Other commonly mutated genes in this cohort were TP53 (62.7%), APC (38.5%) and KRAS (30.4%). Conclusions: TSC1 and/or TSC2 alterations were commonly observed in GI cancers. These cancers were frequently microsatellite stable and of low TMB suggesting that these are actionable alterations that may be candidates for targeted therapy. This hypothesis is being tested in the PRECISION 1 (NCT05103358) trial which is open for enrollment or just-in-time clinical trial sites and available to patients with GI cancers harboring TSC1 or TSC2 alterations.

PRECISION 1: A phase 2, multicenter, open-label basket trial of nab-sirolimus for malignant solid tumors harboring pathogenic inactivating alterations in TSC1 and TSC2.

TPS585 Background: SEER data report that US patients with advanced gastrointestinal (GI) cancers have a poor prognosis as indicated by low 5-year survival rates in patients with colorectal (15.6%), liver (3.5%), and other GI cancers, highlighting the need for more efficacious treatments. Dysregulation of the mTOR pathway contributes to tumor growth and disease progression in many cancers, including GI cancers. The tumor suppressor genes TSC1 and TSC2 are critical negative regulators of mTOR activity whose inactivation can lead to tumor cell growth. Inactivating TSC1 and TSC2 alterations have been observed in GI cancers with a combined frequency of up to 6.5% in hepatocellular carcinoma, 1.7% in colorectal adenocarcinoma and gastrointestinal stromal tumors, and 1.6% in cholangiocarcinoma. nab-Sirolimus, approved in the US for patients with advanced malignant perivascular epithelioid cell tumor (PEComa), is an albumin-bound mTOR inhibitor (mTORi) that inhibits the mTOR pathway via suppression of the mTORC1 complex. In an exploratory analysis of the pivotal AMPECT trial of nab-sirolimus in advanced malignant PEComa (NCT02494570), 8/9 (89%) and 1/5 (20%) patients with inactivating alterations in TSC2 and TSC1, respectively, had a confirmed response. Most treatment-related adverse events were grade 1/2 (none were grade ≥4) and were consistent with mTORi-class adverse events. Based on the clinical observations from AMPECT and the underlying mechanism of action of nab-sirolimus, the PRECISION 1 trial was designed to assess the safety and efficacy of nab-sirolimus in a tumor-agnostic study of patients with advanced cancers harboring TSC1 or TSC2 inactivating alterations. The trial is open to patients with GI cancers with inactivating alterations in TSC1 or TSC2. Methods: In PRECISION 1 (NCT05103358), eligible patients are ≥12 years old and mTORi-naïve, have advanced malignant solid tumors harboring TSC1 or TSC2 inactivating alterations identified using next-generation sequencing (NGS) of tumor tissue or liquid biopsy (confirmed by central review of NGS reports), and have received appropriate standard treatments, per investigator. nab-Sirolimus 100 mg/m2 is given intravenously over 30 min on days 1 and 8 of each 21-day cycle. The primary endpoint is overall response rate per independent radiographic review (IRR) using Response Evaluation Criteria in Solid Tumors v1.1. Other endpoints include duration of response, time to response, progression-free survival by IRR, overall survival, patient-reported quality of life, and safety. Enrollment began in March 2022. Collaboration with leading NGS vendors is expediting the identification of patients with qualifying TSC1 and TSC2 alterations; ongoing study access is facilitated through a just-in-time approach to trial location activation. Clinical trial information: NCT05103358 .

Liquid biopsy-based comprehensive genomic profiling to reveal mutational landscape in real-world patients with gastrointestinal cancer.

735 Background: Molecular characteristics hold substantial clinical significance in cancer. Previous research has elucidated the molecular classification of gastrointestinal (GI) cancers, leveraging biomarkers like gene alterations, MSI, EBV status, and chromosomal instability. However, most of these studies relied on tissue biopsies. Limited investigations have been documented regarding the characterization of molecular profiles through liquid biopsy. Here we present a comprehensive genomic profiling study conducted on advanced GI cancer patients using blood samples. Methods: This prospective study is a part of a global initiative focused on molecular biomarker screening across various solid tumors. Here we report the early result of 106 unresectable GI cancer patients, encompassing those with advanced disease or experiencing relapse after prior treatments. The cohort comprises 66 colorectal cancer (CRC) patients, 34 gastric cancer (GC) patients, and 6 esophageal cancer (EC) patients. Each patient contributed a 10-mL blood sample for comprehensive circulating tumor DNA (ctDNA) analysis. The study employed PredicineCARE, a 152-gene, NGS-based liquid biopsy assay, to profile somatic gene variations within this patient population. Results: The study revealed a total of 1,597 somatic mutations, with 1,077 occurring in CRC, 448 in GC, and 72 in EC. Additionally, 722 gene copy number variants were identified, with 288 in CRC, 351 in GC, and 83 in EC patients. In CRC, the most frequently altered genes (prevalence > 20%) included TP53 (58%), APC (45%), KRAS (33%), and BRCA2 (22%). Conversely, in GC, the most altered genes were TP53 (59%), TERT (35%), FAT1 (29%), ARID1A (26%), and FGFR4 (24%). Among the 6 EC patients, 3 carried TP53 variations, with variations in APC (N=2), ERCC5 (N=2), FAT1 (N=2), and EGFR (N=1) also observed. The mutation burden in CRC (median 3.73 mut/Mb) and GC (median 3.57 mut/Mb) displayed no significant differences. However, the mutation burden in CRC was significantly higher than that in EC (2.24 mut/Mb) (p=0.04). A similar pattern was observed between GC and EC but did not reach statistical significance (p=0.10) due to limitations in cohort size. Furthermore, the assay identified patients carrying both germline and somatic mutations related to homologous recombination deficiency (HRD). In CRC patients, 5 had MLH1 germline mutations, 6 had MSH2 mutations (5 were germline), 4 had MSH6 germline mutations, 2 had PMS2 somatic mutations, and 1 had an EPCAM germline mutation. While in GC patients, 2 had MLH1 germline mutations, 1 had an MSH6 mutation, and 1 had a PMS2 somatic mutation. Conclusions: This study elucidated the comprehensive mutational landscape of advanced gastrointestinal cancer through liquid biopsy, thereby contributing novel biomarkers for clinical diagnosis and facilitating targeted therapy mechanism investigations.

BOLD-100-001 (TRIO039): A phase 2 study of BOLD-100 in combination with FOLFOX in patients with advanced mCRC previously treated with FOLFOX/CAPOX—Efficacy and safety analysis.

143 Background: BOLD-100 is a first-in-class metallotherapeutic with a unique multimodal mechanism of action currently in phase 2 clinical development for the treatment of advanced gastrointestinal cancers. Standard treatment options for patients (pts) with metastatic colorectal cancer (mCRC) include FOLFOX or CAPOX in first or second line therapy. This study explored the benefit of BOLD-100 + FOLFOX in previously treated mCRC patients. Methods: This prospective, phase 2 study evaluates BOLD-100 + FOLFOX in pts with mCRC. All pts received prior standard treatment, including FOLFOX or CAPOX. Pts received 625 mg/m2 of BOLD-100 + FOLFOX on day 1 of each 14-day cycle and treated until progressive disease or unacceptable toxicity. The primary objective is to evaluate PFS, OS, and ORR in treated patients. Disease Control Rate (DCR) was also determined. Results: As of 31Aug2023, 36 pts with advanced mCRC were treated. Median age was 62 years (range 40-78), 56% were women, all pts were ECOG 0 (25%) or 1 (75%). Enrolled pts had a median of 4 prior systemic therapies, including FOLFOX/CAPOX. All but one patient had stage IV disease. On study, pts received a median of 6 cycles of BOLD-100 + FOLFOX [range 1-17]. Five pts remain on treatment with 19 in follow-up. Median PFS was 3.9 [2.7, 5.7] months, median OS 9.6 [6.0, 17] months, ORR 7% [1,20] and DCR 76% [58, 88] in the 29 evaluable pts. Two pts achieved a partial response, and 2 pts had target tumor lesion decreases between 20-29%. Study treatment was well tolerated. Of the 36 treated pts, 33 had 1 or more treatment-emergent adverse events (AEs), most common neutropenia (n=17, 47%), nausea (n=15, 42%), vomiting (n=8, 22%), fatigue (n=7, 19%), infusion related reaction (n=7, 19%), and pruritus (n=6, 17%). Most related AEs were grade (G) 1-2. 15 pts (42%) had G3/4 neutropenia. Despite previous oxaliplatin treatment, fewer than 6% of pts reported peripheral neuropathy or peripheral sensory neuropathy and all were G1/2. Conclusions: BOLD-100 + FOLFOX is an active and well-tolerated treatment in this heavily pre-treated Stage IV mCRC study population. There were no new safety signals. The mPFS, mOS, ORR and DCR data demonstrate significant clinical benefit and improvement over the currently available therapies, with minimal treatment emergent neuropathy or significant toxicities. This promising treatment combination should be further studied. Clinical trial information: NCT04421820 .

Evaluation of a real-world clinico-genomics database of patients with upper gastrointestinal (GI) malignancies in Japan.

400 Background: The genomic profile of gastrointestinal (GI) cancers provides essential information for precision medicine, however, there is limited availability of real-world data in Asian populations as they are not well-represented in most publicly accessible clinico-genomic databases. In this retrospective study, we evaluated the clinical and genomic characteristics of upper GI cancer patients in the database from an academia-industry collaborative nationwide cancer genome screening project in Japan. Methods: The Screening Projectfor Individualized Medicine in Japan (J-SCRUM) GI-SCREEN enrolled advanced GI cancer patients from 26 sites before planned or during systemic therapy from 2015 to 2019. Archived formalin-fixed paraffin-embedded tumor tissue was analyzed by next-generation sequencing (NGS) using Oncomine Cancer Research Panel and Oncomine Comprehensive Assay. Patients with gastric (GC), esophageal (EC) and pancreatic (PC) cancers were identified in the database. The frequency of key actionable genomic alterations in each cancer cohort was explored and compared to similar upper GI cohorts in The Cancer Genome Atlas (TCGA), a publicly available genomics database initiated in 2005 and concluded sample collection in 2013 with most samples from White cancer patients. Results: A total of 872 GC (mean age at registration [SD]: 64y [12]; percent males: 65%), 265 EC (64y [9]; 78%) and 495 PC (64y [10]; 60%) patients were identified. The majority (>70%) of samples were obtained from primary sites. Adenocarcinoma was the most common histological type for GC (85%) ad PC (76%), while squamous cell (76%) was the most common among EC patients. In the GC cohort, the prevalence of key actionable genomic alterations in J-SCRUM GI-SCREEN vs TCGA (N = 380) was, TP53 mutation (49% vs 49%), ERBB2 amplification (14% vs 13%), PIK3CA mutation (11% vs 14%), MYC amplification (9% vs 12%) and MET amplification (2% vs 3%). In the EC cohort, the prevalence in J-SCRUM vs TCGA (N = 182) was TP53 mutation (77% vs 87%), NFE2L2 mutation (21% vs 10%), PIK3CA mutation (9% vs 9%) and CDKN2A mutation (8% vs 8%). In the PC cohort, the prevalence in J-SCRUM vs TCGA (N = 150) was KRAS hotspot mutation (90% vs 93%), KRAS G12D (43% vs 41%), KRAS G12V (32% vs27%), TP53 mutation (58% vs 64%), BRCA1/2 deleterious mutation (5% vs 5%), ATM deleterious mutation (6% vs 5%) and MYC amplification (5% vs 5%). Conclusions: As part of a nationwide cancer genome screening project, J-SCRUM GI SCREEN database provides comprehensive genomic information for Asian population (Japan). The prevalence of key actionable gene alterations in each tumor type was highly comparable between J-SCRUM GI-SCREEN and TCGA data.

First-in-Human Phase I Study of Minnelide in Patients With Advanced Gastrointestinal Cancers: Safety, Pharmacokinetics, Pharmacodynamics, and Antitumor Activity.

Minnelide is a water-soluble prodrug of triptolide. Triptolide is an anticancer agent that targets cancer resistance through several mechanisms. Minnelide was evaluated in a phase I study in patients with advanced GI carcinomas to establish the safety, pharmacodynamic, antitumor activity, and recommended phase II dose (RP2D). Patients with refractory GI carcinoma and with measurable disease on CT scan were eligible. The study used a 3 + 3 dose-escalation scheme. Due to neutropenia toxicity, 2 dosing schedules were evaluated to determine the RP2D for future studies. Response was assessed using RECIST 1.1 and Choi criteria. Minnelide and triptolide PK were evaluated. Patients who completed the first 28-day treatment cycle without DLTs continued treatment until disease progression or unacceptable toxicity. Forty-five patients were enrolled (23 pancreatic cancer, 10 colorectal, and the remaining 9 had other GI tumors); 42 patients received at least one dose of Minnelide. Grade ≥ 3 toxicities occurred in 69% of patients, most common neutropenia (38%). 2 patients with severe cerebellar toxicity who had a 2-fold higher triptolide concentration than other participants. ORR was 4%; the disease control rate (DCR) was 54% (15/28). Choi criteria demonstrated a decrease in average tumor density in 57% (16/28) patients. This first-in-human, phase I clinical study identified a dose and schedule of Minnelide in patients with refractory GI cancers. The primary toxicity experienced was hematologic. Evidence of efficacy of Minnelide treatment in this group of patients was observed. The DCR ranged from ~2 to 6 months in 14/28 (50%) of evaluable patients. Studies in monotherapy and combination treatments are underway.