Abstract 5691: Preclinical evaluation of TFX05-01, a selective AKR1C3- targeted prodrug for solid tumor

Abstract Objective: Aldo-keto reductase 1C3 (AKR1C3), is a member of the aldo-keto reductase superfamily, catalyzing the NADP(H)-dependent stereospecific reduction of various aldehydes and ketones. AKR1C3 is overexpressed in a variety of cancer cells, including hepatocellular carcinoma (HCC), castration-resistant prostate cancer (CRPC), and leukemia cells. This study is to investigate the in vitro and in vivo antitumor activity of TFX05-01, a selective AKR1C3-activated anticancer prodrug, in preclinical models of AKR1C3 overexpressing cells. The studies provide solid foundation for nomination of TFX05-01 for clinical trials. Method: Enzymatic activation of TFX05-01 was investigated in vitro using recombinant human AKR1C3. Cellular anti-proliferative activity was evaluated with a range of AKR1C3 overexpressed or low expressed cell lines. The in vivo antitumor activity was evaluated in various CDX mouse models with high expression of AKR1C3, including HepG2 and castration-resistant prostate VCaP, as well as PDX leukemia models Result: TFX05-01 is a prodrug which selectively releases a DNA alkylating agent (TFX05-01A) upon exposure to AKR1C3. TFX05-01 inhibited cell proliferation in several AKR1C3 overexpressed HCC cell lines with an IC50 ≤ 100 nM. In contrast, TFX05-01 showed much lower anti-proliferative activity in low or no AKR1C3 expressed cells with an IC50 value greater than 1 μM. The cytotoxic potency of TFX05-01 in cancer cells correlates with the level of AKR1C3 expression, and the cytotoxic activity of TFX05-01 was inhibited when used in combination with a specific AKR1C3 inhibitor (IC50: 0.7 nM without inhibitor vs 188 nM with inhibitor in SNU-878 cells). TFX05-01 showed antitumor efficacy in AKR1C3 highly expressed HepG2 subcutaneously implanted xenograft model (TGI = 97% @2 mpk, QW, 3 doses IV). Concomitant PK studies showed that the concentration of active metabolites (TFX05-01A) in tumor was significantly higher (15~50 times) than that in plasma, which correlates with the selective release of the active DNA alkylating agent upon exposure to AKR1C3 in tumor tissues. Conclusion: TFX05-01 is a novel selective AKR1C3-activated prodrug, which is different from traditional non-selective alkylating agents for cancer therapy. Preclinical studies have shown profound in vivo efficacy of TFX05-01 in AKR1C3 overexpressed mouse tumor xenograft models without marked toxicity. TFX05-01 represents a novel treatment option for AKR1C3 expressing solid cancers. Preclinical GLP safety evaluations were promising and TFX05-01 was nominated for clinical trials. Citation Format: Charles Z Ding, Zhe Cai, Wei Sha. Preclinical evaluation of TFX05-01, a selective AKR1C3- targeted prodrug for solid tumor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5691.