MACTIDE-Verteporfin (MACTIDE-V) is an innovative peptide-drug conjugate (PDC) designed to target and reprogram CD206⁺ tumor-associated macrophages (TAMs) in triple-negative breast cancer (TNBC). By combining the MACTIDE peptide (G(CTKSIPPIC)SPGAK-OH, Disulfide: C2-C10) with Verteporfin, this conjugate offers a novel approach to modulating the tumor microenvironment and inhibiting cancer progression. Functionality and Biological Importance: • MACTIDE Peptide: Engineered from the CD206-binding peptide mUNO (CSPGAK-OH), MACTIDE incorporates a trypsin inhibitor loop from Sunflower Trypsin Inhibitor-1 (SFTI-1), enhancing its affinity for the CD206 receptor and increasing proteolytic stability. This modification results in a 15-fold higher binding affinity and a 5-fold longer half-life in tumor environments compared to its predecessor. • Verteporfin: Traditionally used as a photosensitizer in photodynamic therapy, Verteporfin also functions as an inhibitor of the YAP/TAZ pathway, a critical regulator of cell proliferation and survival in cancer cells. Applications in Research: • Targeted Macrophage Reprogramming: MACTIDE-V selectively binds to CD206⁺ TAMs, facilitating their reprogramming from a pro-tumoral to an anti-tumoral phenotype. This shift enhances the immune system's ability to attack tumor cells, thereby inhibiting tumor growth and metastasis. • Therapeutic Efficacy Without Light Activation: Unlike traditional applications of Verteporfin that require light activation, studies have demonstrated that MACTIDE-V exhibits significant anti-tumoral effects even without irradiation. This finding suggests a broader therapeutic potential and simplifies treatment protocols. • Enhanced Immune Infiltration: Treatment with MACTIDE-V has been associated with increased infiltration of cytotoxic lymphocytes, such as CD8⁺ T cells and natural killer (NK) cells, into the tumor microenvironment. This immune modulation contributes to the suppression of tumor progression and metastasis. MACTIDE-Verteporfin (Vert-Ahx-G(CTKSIPPIC)SPGAK-OH) represents a promising advancement in cancer immunotherapy, offering a targeted approach to modulate the tumor microenvironment in triple-negative breast cancer. Its ability to reprogram tumor-associated macrophages and enhance anti-tumor immunity positions it as a valuable asset in ongoing cancer research and therapeutic development. | 