Peroxisome Proliferator-activated Receptor γ Suppresses Proximal α1(I) Collagen Promoter via Inhibition of p300-facilitated NF-I Binding to DNA in Hepatic Stellate Cells

Depletion of peroxisome proliferator-activated receptor gamma (PPARgamma) represents one of the key molecular changes that underlie transdifferentiation (activation) of hepatic stellate cells in the genesis of liver fibrosis (Miyahara, T., Schrum, L., Rippe, R., Xiong, S., Yee, H. F., Jr., Motomura, K., Anania, F. A., Willson, T. M., and Tsukamoto, H. (2000) J. Biol. Chem. 275, 35715-35722; Hazra, S., Xiong, S., Wang, J., Rippe, R. A., Krishna, V., Chatterjee, K., and Tsukamoto, H. (2004) J. Biol. Chem. 279, 11392-11401). In support of this notion, ectopic expression of PPARgamma suppresses hepatic stellate cells activation markers, most notably expression of alpha1(I) procollagen. However, the mechanisms underlying this antifibrotic effect are largely unknown. The present study utilized deletion-reporter gene constructs of proximal 2.2-kb alpha1(I) procollagen promoter to demonstrate that a region proximal to -133 bp is where PPARgamma exerts its inhibitory effect. Within this region, two DNase footprints with Sp1 and reverse CCAAT box sites exist. NF-I, but not CCAAT DNA-binding factor/NF-Y, binds to the proximal CCAAT box in hepatic stellate cells. A mutation of this site almost completely abrogates the promoter activity. NF-I mildly but independently stimulates the promoter activity and synergistically promotes Sp1-induced activity. PPARgamma inhibits NF-I binding to the most proximal footprint (-97/-85 bp) and inhibits its transactivity. The former effect is mediated by the ability of PPARgamma to inhibit p300-facilitated NF-I binding to DNA as demonstrated by chromatin immunoprecipitation assay

Immune modulation after Toca 511 and Toca FC treatment of colorectal cancer patients

186 Background: Toca 511 (vocimagene amiretrorepvec) is a cancer-selective, retroviral replicating vector encoding yeast cytosine deaminase that converts 5-fluorocytosine (5-FC) into 5-fluorouracil in the tumor microenvironment (TME). In animal models, Toca 511 and 5-FC kill dividing cancer and nearby immunosuppressive cells, leading to antitumor immune activity. A Phase 1 study of Toca 511 & Toca FC (extended-release 5-FC) in patients with recurrent high grade glioma revealed results consistent with this proposed mechanism. A Phase 3 trial is ongoing. Methods: Toca 6 (NCT02576665) is a Phase 1b, single-arm, multicenter study designed to investigate immunological changes after Toca 511 & Toca FC treatment in patients with advanced solid tumors, including colorectal cancer (CRC). Patients received intravenous (IV) Toca 511 for 3 days, and underwent biopsy of metastatic tumor before and ~ 4 weeks after starting oral Toca FC. Toca FC was repeated every 4-6 weeks. Peripheral blood mononuclear cells and tumor biopsies were evaluated for treatment related immune responses. Results: 17 CRC patients with a median 5 lines of prior chemotherapy were enrolled. At last data cut-off, 9 patients were alive and the median overall survival was 9.4 months. A patient receiving concomitant panitumumab had a partial response. IV Toca 511 led to viral expression in tumor, which decreased post-Toca FC while maintaining a reservoir of virus in the remaining tumor. T cells shifted from naïve to effector phenotypes, CD4 memory T cells expanded, and/or B cells increased after Toca FC treatment in 36% of patients. Marked changes in tumor infiltrating cells (CD11b myeloid cells, Tregs, exhausted T cells and CD8 T cells) occurred after Toca FC treatment. Treatment has been generally well tolerated. We also plan to report insights gained from RNA analysis of TME and update on clinical finding. Conclusions: Clinical data suggest a signal of activity in these heavily pretreated CRC patients warranting further exploration. IV Toca 511 administration showed viral infection of CRC metastatic tumor. Toca 511 & Toca FC may be associated with T cell mediated immune activity in peripheral blood and metastatic tumor, consistent with pre-clinical data in multiple tumor types. Clinical trial information: NCT02576665

Abstract CT182: Oncolytic virus CF33-hNIS for the treatment of advanced cancer

Abstract Background: CF33-hNIS is a novel vaccinia virus engineered with the human sodium-iodide symporter (hNIS) gene. CF33-hNIS selectively replicates in tumor cells and promotes anti-tumor immunity. Here, we report results on a first-in-human phase 1 dose escalation study of CF33-hNIS, administered intratumorally (IT) or intravenously (IV) in adult patients with metastatic or advanced solid tumors (MAST). Methods: The MAST study is evaluating the safety of CF33-hNIS administered IT or IV, alone or in combination with pembrolizumab in patients with advanced or metastatic solid tumors with ≥ 2 prior lines of therapy (NCT05346484). CF33-hNIS is administered in 21-day cycles on C1D1 and C1D8, then D1 of each cycle thereafter. Pembrolizumab begins C2D1 for the combination groups and is administered Q3W. The study consists of two parts. Part 1 follows a 3+3 dose escalation scheme independent of each route of CF33-hNIS administration (IT and IV) and for each therapy regimen (monotherapy and combination therapy) with up to 7 dose levels of CF33-hNIS ranging from 8.6x105 to 3.0x109 PFU. Part 2 is a cohort expansion in select indications at the optimal dose. The co-primary endpoints are safety and identification of the recommended phase 2 dose. Secondary endpoints include objective response rate according to RECIST v1.1 and iRECIST, and assessment of viral replication in tumor lesions via Single-Photon Emission Computerized Tomography (SPECT). Results: As of Dec 2023, 36 patients have been treated in Part 1 of the study with a median age of 59 (range 23-81). Twenty-two (61%) patients were heavily pretreated with ≥3 prior lines of systemic therapy, and 14 (39%) received prior treatment with checkpoint blockade. Treatment-related adverse events consisted predominantly of ‘flu-like’ symptoms, such as grade 1/2: fatigue (31%), pyrexia (22%), and chills (14%). No dose-limiting toxicities have occurred. The highest dose treated to date is 1.1x108 PFU by IT and IV delivery; dose escalation continues. In the IT cohorts (14 patients), 7 of 15 (47%) injected lesions had a reduction in tumor burden, three lesions were completely eradicated. Three patients (21%) had an objective response: one complete response by iRECIST in a patient with cholangiocarcinoma; and two partial responses in patients with melanoma by RECIST. In IV cohorts (17 patients), 53% of patients achieved stable disease as their best response. Patients who received prior checkpoint blockade therapy derived clinical benefit with and without pembrolizumab. Viral replication, assessed by SPECT was higher in patients that saw a reduction in tumor burden. Immunological changes in peripheral blood and tumor biopsies will be presented. Conclusions: CF33-hNIS alone or in combination with pembrolizumab is a safe treatment option for advanced cancer patients. Encouraging efficacy has warranted advancement to part 2 of this study with a cohort expansion of patients with cholangiocarcinoma and other tumor types. Citation Format: Daneng Li, Anthony F. Shields, Hirva Mamdani, Patrick Travis, Gavin Wright, Wallace Akerley, Alex Spira, Gregory Daniels, Jaime Merchan, Abhijeet Kumar, Emerson Lim, Colt Egelston, Oscar Flores, Stanley Hamilton, Janet Austria, Amanda Seiz, Sharon Yavrom, Seymour Fein, John Byon, Paul Woodard, Grey A. Wilkinson, Jennifer Leddon. Oncolytic virus CF33-hNIS for the treatment of advanced cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT182

Preclinical and Clinical Observations Implying Combination Therapy to Enhance the Efficacy of the Her-2/neu B-Cell Peptide-Based Vaccine HER-Vaxx and to Prevent Immune Evasion

Her-2/neu-targeting therapy by passive application with trastuzumab is associated with acquired resistance and subsequent metastasis development, which is attributed to the upregulation of tumoral PD-L1 expression and the downregulation of Her-2/neu. We aimed to investigate this association, following active immunization with our recently constructed B-cell peptide-based Her-2/neu vaccines in both preclinical and clinical settings. Immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), and combined positive score (CPS) were applied to evaluate Her-2/neu and PD-L1 expression using a murine syngeneic tumor model for Her-2/neu lung metastases and tumor biopsies from a gastric cancer patient with disease progression. A significant and concomitant reduction in Her-2/neu and the upregulation of PD-L1 expression was observed in vaccinated mice after 45 days, but not after 30 days, of metastases development. A significant increase in tumor-infiltrating B lymphocytes was observed at both time points. The downregulation of Her-2/neu and the upregulation of PD-L1 were observed in a patient\u27s primary tumor at the disease progression time point but not prior to vaccination (Her-2/neu IHC: 3 to 0, FISH: 4.98 to 1.63; PD-L1 CPS: 0% to 5%). Our results further underline the need for combination therapy by targeting PD-L1 to prevent metastasis formation and immune evasion of Her-2/neu-positive and PD-L1-negative tumor cells