Peritoneal carcinomatosis is a major cause of death in gastric cancer, yet effective therapies remain limited. Tumor-derived soluble factors are increasingly recognized as key regulators of the peritumoral microenvironment. Here, we nominate osteopontin (SPP1) as a tumor-derived mediator that orchestrates macrophage-driven immunoregulation. Using integrated multi-omic analyses across human and murine models, we show that tumor-secreted SPP1 promotes macrophage recruitment and induces tolerogenic IL-10 production. Clinically, SPP1 correlated with worse overall survival and progression-free survival in gastric cancer. In murine syngeneic models of gastric peritoneal carcinomatosis, intracavitary pharmacologic inhibition of SPP1 restricted peritoneal dissemination. SPP1 inhibition also impaired macrophage trafficking and IL-10 production in-vitro and in-vivo. In addition, macrophage depletion phenocopied SPP1 inhibition by limiting peritoneal dissemination. These findings define a mechanism of tumor-macrophage crosstalk mediated by SPP1. We also provide rationale for SPP1-targeted therapies in gastric peritoneal carcinomatosis.

Different combination treatments of TVB-3664, irinotecan and olaparib were well tolerated in vivo

TVB-3664 treatment blocks the recruitment of DNA repair proteins to the DNA damage sites

Purpose High-risk neuroblastoma presents a serious clinical challenge with survival rates below 50%. Disease relapse most commonly occurs at distant metastatic sites and remains the primary driver of poor outcomes, emphasizing the need for therapies to target drivers of relapse. Experimental design This study identified DNA-PKcs as a critical determinant of poor survival and metastatic relapse in neuroblastoma patients. We evaluated which therapeutic modality—chemotherapy or radiotherapy—when combined with DNA-PKcs inhibition, more effectively reduces metastatic burden and prevents recurrence. Results Colony-forming assays revealed that established neuroblastoma colonies resist doxorubicin alone and require high-dose doxorubicin paired with DNA-PKcs inhibition to suppress progression. In contrast, low-dose radiotherapy in combination with DNA-PKcs inhibition effectively controlled colony progression. Maximal synergy between radiotherapy and DNA-PKcs inhibition was achieved when the inhibitor was administered within 4 h post-irradiation. Chronic co-exposure to doxorubicin and peposertib encouraged emergence of therapy-resistant cells, whereas chronic co-exposure to radiotherapy combined with peposertib disrupted neuroblastoma cells self-renewal and prevented long-term colony maintenance. In neuroblastoma metastases, adding DNA-PKcs inhibition to doxorubicin improved efficacy but induced gastrointestinal side effects and failed to eradicate tumors; pairing it with low-dose, fractionated radiotherapy resulted in total lesion regression, impaired tumor self-renewal, and prevented systemic adverse effects. Conclusions Our findings correlate elevated DNA-PKcs levels with poor patient prognosis and show that low-dose radiotherapy combined with peposertib effectively abrogates neuroblastoma self-renewal compared to chemotherapy-based regimens, thereby implicating DNA-PKcs as a key mediator of metastatic relapse and supporting radiotherapy plus DNA-PKcs inhibition as a compelling therapeutic strategy for relapsed or refractory high-risk neuroblastoma.

The peritoneum is the mesothelial lining of the peritoneal cavity and its contained viscera; it functions as a bidirectional dialysis membrane and thus plays a major role in defending against inflammatory processes of the abdomen. The peritoneum is the key organ involved in sensation of abdominal pain and is thus integral to diagnosing abdominal pathology.

TVB-2640 treatment decreases lipid species in patient plasma samples using lipidomic analysis

FASN inhibition synergizes with irinotecan to promote DNA damage and inhibit colony formation in colon cancer cells

Characteristics of patients in Cohort 2 from whom tumor samples and adjacent normal colon tissues were obtained

Abstract Background: Pancreatic neuroendocrine tumors (pNETs) frequently present with extensive inoperable metastases that develop resistance to DNA-damaging chemotherapy. This study evaluated DNA-PK inhibition as a strategy to enhance doxorubicin efficacy against metastatic tumors and examined the DNA-PK-CDK2 axis, with PRKDC identified as a regulator of CDK2 expression. Methods: DNA double-strand breaks were induced using the topoisomerase II inhibitor doxorubicin. DNA-PK activity was inhibited with peposertib or via siRNA-mediated DNA-PK knockdown in BON and QGP-1 neuroendocrine cell lines. Transcriptomic data from DNA-PK knockdown cell lines were analyzed to identify gene expression relationships. Dose-dependent effects of doxorubicin on CDK2 levels were evaluated by western blot and confocal microscopy. The effect of DNA-PK inhibition and knockdown on doxorubicin-induced CDK2 expression was assessed by western blot. Therapeutic efficacy of combined low-dose doxorubicin (2 mg/kg, i.p.) and peposertib (100 mg/kg, oral gavage) was evaluated in a BON metastatic lung colonization mouse model using bioluminescence imaging to quantify metastatic burden. Results: In BON and QGP-1 cells, doxorubicin consistently induced CDK2 upregulation, and both Western blotting and confocal microscopy showed a dose-dependent increase in CDK2 protein levels, implicating a chemotherapy-activated program of adaptive resistance. Transcriptomic analyses revealed a positive correlation between PRKDC (encoding the DNA-PK catalytic subunit) and CDK2 expression. Importantly, PRKDC knockdown or pharmacologic DNA-PK inhibition prevented this CDK2 induction, establishing a PRKDC-dependent mechanism of CDK2-mediated chemoresistance and identifying DNA-PK as a therapeutic target to block the adaptive response. Consistent with these in vitro findings, two cycles of low-dose doxorubicin combined with peposertib markedly suppressed pulmonary metastatic growth and limited extrathoracic dissemination in a BON lung metastasis model. Conclusions: These findings support a role for DNA-PK in mediating CDK2 upregulation in response to chemotherapy and highlight the clinical relevance of low PRKDC and CDK2 expression with improved survival in NET patients. Collectively, these findings identify a PRKDC-CDK2 survival axis as a driver of chemoresistance and demonstrate that sustained, low-intensity DNA damage, when coupled with selective DNA-PK inhibition, disrupts this adaptive program, substantially reduces metastatic burden, and delivers more durable responses in pNETs. AI use disclosure: Portions of this abstract were revised with the assistance of generative AI and were fully reviewed and verified by the authors. Citation Format: Subin Kim, Mahnaz Norouzi, Courtney M. Townsend, B. Mark Evers, Piotr Rychahou. PRKDC regulates CDK2 expression and pancreatic neuroendocrine cancer sensitivity to chemotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 1265.

TVB-3664 treatment enhances irinotecan induced cytotoxicity in PDOs

Altered lipid metabolism is a potential targetable metabolic vulnerability in colorectal cancer. Fatty acid synthase (FASN), the rate-limiting enzyme of de novo lipogenesis, is an important regulator of colorectal cancer progression, but the FASN inhibitor TVB-2640 showed only modest efficacy in reducing tumor burden in preclinical studies, suggesting that combination strategies might be required to prolong patient survival. In this study, by using samples from a window trial of TVB-2640 treatment in patients with colorectal cancer, we found that FASN inhibition induced DNA damage but impaired the DNA damage response (DDR). In colon cancer cell lines and patient-derived organoids, FASN inhibition potentiated chemotherapy-induced double-strand DNA breaks and apoptotic cell death by altering histone acetylation. In addition, FASN inhibitor treatment blocked DDR by decreasing ATM expression and CHK2 phosphorylation. Mechanistically, FASN inhibition decreased activation of the DDR pathway by attenuating BRCA1 and ATM recruitment to γH2AX foci in an acetylation-dependent manner. Moreover, FASN inhibition-mediated DNA repair deficiency induced synthetic lethality with PARP inhibition in colon cancer cells. Importantly, combining FASN inhibition with the chemotherapeutic drug irinotecan synergistically decreased xenograft tumor growth and delayed tumor relapse, which was potentiated by the PARP inhibitor olaparib as maintenance treatment. Taken together, this study describes a therapeutic strategy in which FASN inhibitors can be utilized to delay tumor recurrence after chemotherapy, which is a major challenge in patients with colorectal cancer. SIGNIFICANCE:FASN inhibition attenuates DNA damage repair to potentiate the efficacy of chemotherapy and to promote synthetic lethality with PARP inhibitors, offering a potential combination strategy to reduce tumor recurrence in colorectal cancer.

Addition of exogenous lipids rescues ATM expression in TVB-3664 treated colon cancer cells

TVB-3664 treatment increases protein acetylation and decreases ATM protein expression

Effectively activating protective CD8+ T cell immunity specifically against cancer antigens is an important pathway to prevent the growth of various types of cancers. A major obstacle in this approach is variations in cancer antigens among patients. A valuable material to overcome the antigen variation among cancer patients is the use of each individual’s own cancer cells for immunization. In colorectal cancer (CRC), approximately one-third of the patients who receive curative surgical resection have a recurrence of cancer. Therefore, the use of surgically resected CRC for immunotherapy to specifically activate the protective CD8+ T cells against their own cancer cells is a valuable approach to prevent the recurrence of cancer. However, since cancer-specific antigens are often not strongly immunogenic, a potent immunostimulant is required as an adjuvant for efficiently facilitating the activation of cancer-specific protective CD8+ T cells. We recently identified that a protein molecule, the amino-terminus region of the dense granule protein 6 (GRA6Nt) of Toxoplasma gondii, selectively activates innate expressions of IFN-γ and IL-18 and functions as a powerful adjuvant when used in immunization with nonreplicable (treated with mitomycin C or irradiated) MC38 CRC cells to potently activate the cytotoxic activity and IFN-γ production of CD8+ T cells against cancer cells. In addition, immunization using the GRA6Nt protein adjuvant effectively inhibits the growth of identical CRC cells after its challenge implantation, which mimics a recurrence of the surgically resected CRC used for the immunizations. In contrast to the two nucleotide- or deoxynucleotide-based Toll-like receptor agonists currently being used as adjuvants in cancer immunotherapy in clinical settings, GRA6Nt is a protein molecule. Thus, the rGRA6Nt protein adjuvant provides a new pathway in cancer immunotherapy to effectively activate the protective CD8+ T cells specific for the individual’s cancer cells to prevent the recurrence of surgically resected CRC in patients.

Characteristics of patients enrolled in clinical trial (Cohort 1)

Effect of FASN inhibition in normal vs tumor samples