journal contribution
posted on 2025-06-04, 07:21 authored by Victoria M. Valvo, Qiang Zhang, Long Jiang, Erin A. Holcomb, Ashley N. Pearson, Anna G. Edmunds, Hailey G. Faulkner, Jadyn G. James, Akshay Tate, Amanda K. Huber, Zhuwen Wang, Yupei Guo, David Karnak, Leslie A. Parsels, Joshua D. Parsels, Yu L. Lei, Alnawaz Rehemtulla, Heng Lin, Eileen S. Carpenter, Daniel R. Wahl, Vaibhav Sahai, Theodore S. Lawrence, Michael D. Green, Meredith A. Morgan Supplemental Figure 3. (A) UMAP projections of all cell clusters from harvested subcutaneous mT4 tumors following 5 days of treatment. Mice were treated with 1 dose (8 Gy) radiation on day 0, five doses olaparib (50 mg/kg) on days 0-4, and two doses of αPD-L1 (100 µg) on days -1, and 2. Tumors were harvested on day 4. (B) Dotplot showing an incomplete list of markers used to name cell clusters. The size of the circle represents the percentage of cells within that cluster that express the given gene. The color represents the average fold change expression of that gene within that cluster. (C) Gene signature analysis conducted on all cells for the listed immune signaling pathways. Enrichment module (EM) scores were calculated from gene signature scores using the following equation: (1/2 x Q2) + (1/4 x Q1) + (1/4 x Q3). EM scores for the indicated pathways were combined to create the resultant heatmap. (D, G) PDAC (D) and myeloid (G) cell clusters colored by corresponding treatment group (D) or by cell identity (G). (E) Gene signature analysis on PDAC cells for immune signaling pathways. Gene signature module scores were averaged and combined for each of the listed pathways to make the resultant heat map. (F, H) GSEAplots of important pathways which showed enrichment in PDAC cell comparisons (F) or myeloid cell comparisons (H) following GSEA. These include G2M checkpoint, interferon alpha response, interferon gamma response, and UV response down for the comparison between olaparib+radiation+αPD-L1 PDAC cells and radiation+αPD-L1 PDAC cells (F), interferon gamma response and interferon alpha response for the comparison between olaparib+radiation+αPD-L1 myeloid cells and control treatment myeloid cells, and TGFβ signaling and oxidative phosphorylation for the comparison between olaparib+radiation+αPD-L1 myeloid cells and radiation+αPD-L1 myeloid cells (H). (I) Violin plots displaying gene signature analysis conducted on macrophages for M2 macrophage phenotype and phagocytosis. Statistical significance was determined by Wilcoxon test. *P<0.05, **P<0.01, ***P<0.001, ****P<0.0001
Funding
National Institutes of Health (NIH)
History
ARTICLE ABSTRACT
PARP inhibitors sensitize pancreatic ductal adenocarcinoma (PDAC) to radiation by inducing DNA damage and replication stress. These mechanisms also have the potential to enhance radiation-induced type I interferon (T1IFN)–mediated antitumoral immune responses. We hypothesized that the PARP inhibitor olaparib would also potentiate radiation-induced T1IFN to promote antitumor immune responses and sensitization of otherwise resistant PDAC to immunotherapy. To test this hypothesis, we assessed the effects of olaparib and radiation on T1IFN production and sensitivity to αPD-L1 immunotherapy, as well as on the tumor microenvironment by single-cell RNA sequencing. We found that olaparib enhanced T1IFN production after radiation and had superior therapeutic efficacy in immunocompetent models. Olaparib and radiation treatment sensitized PDAC tumors to αPD-L1, resulting in decreased tumor burden and a 33% complete response rate. Combination treatment provided durable immune responses as shown by tumor rejection upon tumor rechallenge of previously cured mice. Furthermore, single-cell RNA sequencing analysis revealed that combination treatment induced an immunogenic tumor microenvironment characterized by interferon (IFN) responses in both PDAC and myeloid cell populations, macrophage polarization, and increased CD8+ terminal effector T-cell frequency and activity, findings which were confirmed by IHC and flow cytometry. Furthermore, CD8+ T cells and T1IFN signaling were required for therapeutic efficacy as host depletion of CD8+ T cells or the T1IFN receptor diminished treatment responses. Overall, our results indicate that olaparib enhances radiation-induced T1IFN-mediated immune signaling and subsequently an adaptive immune response, thus sensitizing pancreatic cancer to αPD-L1 therapy, supporting an ongoing clinical trial of this therapy in patients with PDAC.See related commentary by Buchsbaum, p. 840
