Abstract 679: TXB-001 is an upgraded conjugated anthracycline that targets tumors with reduced risk of cardiotoxicity, hand-foot syndrome and alopecia
Authors: Oshida Keiyu , Hirakata Mikito , Tomikawa Emi , Sakai Chizuka , Uchida Masashi , Shimozono Rieko , Izawa Akiko , Koga Yoko , Okano Tsubasa , Narumi Hideki , Munakata Lisa , Suzuki Ryo , Nonaka Miki , Uezono Yasuhito 
Published: March 2024

Abstract
TXB-001 is a well-optimized N-(2-hydroxypropyl)methacrylamide copolymer-based conjugated pirarubicin (THP) and a novel candidate for developing anticancer drugs. It exhibits tumor-specific accumulation due to the enhanced permeability and retention effects and prolonged circulation time compared with free THP. Its hydrazone bond is dissociated under lower pH conditions, providing selective and rapid release of THP in acidic tumor environments. Therefore, TXB-001 is expected to have high efficacy and low toxicity. Anthracycline anticancer drugs have been widely used for the treatment of several cancers, but their use is limited by several adverse effects (AEs), including cardiotoxicity, which is a life-threatening AE. Furthermore, the maximum lifetime cumulative dose is decided for each anthracycline in clinical use, which leads to discontinuation of the medication. Hand-foot syndrome (HFS) is a dose-limiting AE of DOXIL®, a liposomal formulation of doxorubicin (DOX), and although it is not a life-threatening condition, it significantly deteriorates quality of life (QOL). Alopecia is another common AE, which is relatively noninvasive but adversely affects mental health and reduces QOL. In this study, we confirmed the efficacy of TXB-001 in a mice triple-negative breast cancer (TNBC) model and evaluated the cardiotoxicity-, HFS- and alopecia-inducing effects of TXB-001 in mice and rats to compare the severity with existing anthracycline anticancer drugs, including DOXIL®. The pharmacokinetic (PK) analysis in several tissues, including plasma, tumor, heart, skin of the chest, and palmar and plantar areas, was also performed after a single intravenous administration in rodents. As a result, TXB-001 showed an equivalent or greater antitumor effects than other anthracyclines in the TNBC model, and the AEs were scarcely observed. TXB-001 did not decrease left ventricular ejection fraction, with no or little HFS-like changes compared with DOXIL®, which showed significant histopathological changes. TXB-001 also showed weaker alopecia-inducing effects than DOX, DOXIL®, and THP. In the PK analysis, TXB-001 was distributed in the tumor at a higher concentration than in other tissues, except for plasma. Hence, most of the THP, the active ingredient, was released in the tumor. The exposure of the heart in the TXB-001-treated group was one-tenth of that in the DOXIL®-treated group. Moreover, accumulation in the skin, especially in palmar and plantar areas, was observed for DOXIL®, but no accumulation in the skin was observed for TXB-001. This PK profile consistently demonstrated the antitumor activity of TXB-001, without AEs. TXB-001 reduces the chance of dose-limiting and QOL-threatening AEs, and thus, cancer patients can continue treatment, making it a more convenient anticancer drug in clinical use with a wide safety margin.
Citation Format: Keiyu Oshida, Mikito Hirakata, Emi Tomikawa, Chizuka Sakai, Masashi Uchida, Rieko Shimozono, Akiko Izawa, Yoko Koga, Tsubasa Okano, Hideki Narumi, Lisa Munakata, Ryo Suzuki, Miki Nonaka, Yasuhito Uezono. TXB-001 is an upgraded conjugated anthracycline that targets tumors with reduced risk of cardiotoxicity, hand-foot syndrome and alopecia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 679.