Abstract A121: Turning cold pancreatic tumors hot: Antitumor activity of Annamycin is partially mediated by CD8+ T cell cytotoxicity
Krzysztof Grela, Stanislaw Skora, Izabela Fokt, Nermin Kahraman, Mihai Gagea, Angela Alistar, Waldemar PriebeAbstract
Background:
Annamycin (ANN) is a potent topoisomerase II (TOPO II) poison and non- cardiotoxic analog of doxorubicin (DOX). TOPO II is a promising therapeutic target in pancreatic ductal adenocarcinoma (PDAC). However, DOX has failed to demonstrate therapeutic benefits, likely due to its poor pancreas and pancreatic tumor penetration and retention. In contrast, we recently demonstrated that ANN exhibits superior pancreas uptake vs. DOX as well as pancreatic tumor penetration and produces marked antitumor activity in both human and murine preclinical models of PDAC. Notably, ANN not only potently induces DNA damage, as evidenced by increased phosphorylation of histone H2AX (γH2AX), the primary cytotoxic mechanism of anthracyclines, but also importantly enhances infiltration of CD8+ cytotoxic T cells and CD4+ T cells into the tumor microenvironment (TME), suggesting that immune activation contributes to its antitumor activity.
Objective:
To determine the contribution of CD8+ cytotoxic T cells to the antitumor activity of liposomal Annamycin (L-ANN) in an orthotopic syngeneic mouse model of PDAC.
Methods:
C57BL/6 albino mice were orthotopically implanted with 1×105 KPC-Luc cells. Tumor progression was monitored by bioluminescence imaging (BLI). On day 7 after tumor implantation, mice (n=28) were randomized for treatment with L-ANN in the presence of either CD8-neutralizing antibodies or isotype control antibodies. Animals were euthanized on day 21, and tumors were harvested and weighed to measure tumor burden. Artificial intelligence (AI)-based tools were used solely for proofreading the abstract.
Results:
To investigate the role of adaptive immunity in mediating the antitumor effects of L-ANN, CD8+ T-cell depletion studies were performed. Tumor-bearing mice received L-ANN in combination with either CD8-neutralizing antibodies or isotype control antibodies. Depletion of CD8+ T cells significantly attenuated the antitumor efficacy of L-ANN compared with mice receiving L-ANN plus isotype control antibodies. Although L-ANN retained measurable antitumor activity following CD8+ T-cell depletion, the significant reduction in treatment efficacy demonstrates that L-ANN-induced CD8+ cytotoxic T lymphocytes contribute substantially to the overall therapeutic response. These findings provide functional evidence that the antitumor activity of L-ANN is mediated not only by direct induction of tumor cell DNA damage, but also through activation of antitumor immune responses.
Conclusions:
L-ANN is currently being evaluated in a Phase III clinical trial in patients with acute myeloid leukemia (AML) (MIRACLE study, MB-108). The robust antitumor activity observed in preclinical PDAC models supports continued clinical development of L-ANN for the treatment of PDAC. Furthermore, the demonstration of CD8+-mediated antitumor immunity suggests that L-ANN, in addition to its potent anticancer effects as a single agent, may be particularly well suited for combination strategies with immune checkpoint blockade (ICB) therapies to treat “cold” tumors.
Citation Format:
Krzysztof Grela, Stanislaw Skora, Izabela Fokt, Nermin Kahraman, Mihai Gagea, Angela Alistar, Waldemar Priebe. Turning cold pancreatic tumors hot: Antitumor activity of Annamycin is partially mediated by CD8+ T cell cytotoxicity [abstract]. In: Proceedings of the AACR Conference on Pancreatic Cancer: New Frontiers in Biology and Therapeutic Development; 2026 Sep 25-28; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(18_Suppl_2):Abstract nr A121.