Pharosgen Co. Ltd.

Tumor heterogeneity is a major obstacle to effective targeted therapies, including those utilizing antibody-drug conjugates (ADCs). Although some ADCs employ the bystander effect to eliminate neighboring antigen-negative cells, their efficacy often diminishes as antigen-positive cell populations decrease within heterogeneous tumors. To address this limitation in ADC therapies, we developed a novel ADC using a caspase substrate, Asp-Glu-Val-Asp (DEVD), as a linker to generate a more potent and sustained bystander effect. The DEVD ADC effectively targeted antigen-positive cells and released its payload via cathepsin B cleavage. Notably, it exhibited a significant bystander effect mediated by the caspase-3-triggered extracellular cleavage of the linker, enhancing payload release into the tumor microenvironment. In breast cancer xenograft models, the DEVD ADC maintained its efficacy and continued to exert a bystander effect even after the depletion of antigen-positive cells, thereby overcoming challenges posed by tumor heterogeneity. These findings emphasize the potential of DEVD linkers in enhancing ADC efficacy against heterogeneous solid tumors, offering a promising strategy to improve therapeutic outcomes.

Oncogenic Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations are highly prevalent in pancreatic ductal adenocarcinoma (PDAC) and have garnered attention as potential targets for targeted therapies, such as KRAS inhibitors. However, the limited therapeutic efficacy of KRAS allele-specific inhibitors necessitate an efficient pan-KRAS cancer cell killing strategy. Here, we have examined enhanced macropinocytosis pathway in KRAS mutant cancer cells and report improved intracellular delivery of albumin-based therapeutics. We further established an albumin-binding peptide-docetaxel conjugate platform (MPD3), which has a caspase-3 cleavable feature, for macropinocytosis-targeted bystander payload delivery and realization of bystander killing of pan-KRAS cancer cells, complemented with caspase-3 mediated activation of MPD3 to bolster tumoral accumulation of cytotoxic payloads. Utilization of in vitro co-culture system of pan-KRAS cancer cells and pharmacodynamic marker staining revealed potent bystander killing effects of MPD3, highlighting MPD3 as an efficient delivery platform against pan-KRAS cancer. Moreover, MPD3 elicited robust anti-tumor activities in both local and liver metastatic PDAC tumor models in mice. Overall, this work establishes a paradigm for developing translational pan-KRAS cancer treatment and broadens the applicability of albumin binding peptide-drug conjugate against albumin-metabolism enriched cancers.

Despite significant progress in combining cancer immunotherapy with chemotherapy to treat triple negative breast cancer (TNBC), challenges persist due to target depletion and tumor heterogeneity, especially in metastasis. Chemotherapy lacks precise targeting abilities, and targeted therapy is inadequate in addressing the diverse heterogeneity of tumors. To address these challenges, we introduce RGDEVD-DOX as a tumor-specific immunogenic agent, namely TPD1, which targets integrin αvβ3 and gets continuously activated by apoptosis. TPD1 facilitates the caspase-3-mediated in situ amplification that results in tumor-specific accumulation of doxorubicin. This local concentration of doxorubicin induces immunogenic cell death and promotes the recruitment of immune cells to the tumor site. Notably, the tumor-targeting capabilities of TPD1 help bypass the systemic immunotoxicity of doxorubicin. Consequently, this alters the tumor microenvironment, converting it into a 'hot' tumor that is more susceptible to immune checkpoint inhibition. We demonstrated the anti-metastatic and anti-cancer efficacy of this treatment using various xenograft and metastatic models. This study underscores the high potential of caspase-3 cleavable peptide-drug conjugates to be used in conjunction with anti-cancer immunotherapies.