Antibody-dual drug conjugates for eradicating triple-negative breast cancer with heterogeneity

摘要

ABSTRACT Triple-negative breast cancer (TNBC) is an aggressive and refractory subtype of breast cancer for which limited clinical options are currently available. Although initially responsive to platinum-based neoadjuvant chemotherapy, patients with metastatic TNBC rarely survive 5 years after diagnosis. Most TNBC tumors consist of heterogeneous cell populations with different gene expression profiles. This heterogeneity contributes to drug resistance, early relapse, and therapeutic failure. Although extensive research efforts have made a few clinical options available, developing therapeutics that can effectively eradicate a broad range of TNBC cell populations remains a challenge. Antibody-based drugs such as antibody-drug conjugates (ADCs) are the most promising targeted therapeutic modality for treating TNBC. Trophoblast cell-surface antigen 2 (TROP2) is a protein overexpressed in more than 80% of TNBC, representing a promising molecular target. Recently, Sacituzumab Govitecan (Trodelvy), a TROP2-targeted antibody-drug conjugate (ADC), was granted accelerated approval for the third or later line of treatment of metastatic TNBC. However, TNBC often relapses after continuous treatment; the intratumor heterogeneous expression of TROP2 and drug resistance induced by its payload SN-38 likely contribute to poor clinical outcomes. In addition, patients treated with Trodelvy often suffer from adverse effects, including neutropenia. Thus, enhancing the efficacy, expanding the target scope, and ensuring the safety of this drug class remain critical clinical needs to develop safe and effective therapies for patients with heterogeneous TNBC. We have developed novel ADC technologies, including: 1) peptide linkers for maximizing ADC therapeutic index, and 2) bifunctional chemical spacers and a site-specific conjugation for generating homogeneous ADCs containing two distinct payloads (termed dual-drug ADCs). Specifically, our dual-drug ADCs containing two different antimitotic agents showed greatly improved safety and efficacy in mouse models of HER2-low refractory breast cancer compared with the FDA-approved ADCs Kadcyla and Enhertu. Based on this success and our preliminary data, we hypothesize that optimally designed anti-TROP2 dual-drug ADCs effectively eradicate a broad range of solid and metastatic TNBC tumors. In Aim 1, we will investigate how our novel linkers are processed in cancer and normal cells by cell-based assays, proteomic analysis, and in vivo biodistribution analysis. In Aim 2, we will synthesize novel DNA-alkylator payloads and potentiators with varying chemical properties. We will then prepare a series of anti-TROP2 dual- drug ADCs varying in the combination and the number of drugs conjugated to the antibody. In Aim 3, we evaluate the dual-drug ADCs for toxicity efficacy in TNBC mouse models. Successful completion of this project will lay the foundations for this novel drug class with the potential to overcome heterogeneity and resistance of TNBC, which may eventually revolutionize current therapeutic strategies for this devastating disease.