Combination Therapy with a TLR7 Agonist and a BRD4 Inhibitor Suppresses Tumor Growth via Enhanced Immunomodulation

Area of Science:

• Immunology
• Oncology
• Pharmacology

Background:

• JQ-1, a BRD4 inhibitor, shows antitumor potential but faces clinical toxicity challenges.
• SZU-101 is a novel TLR7 agonist with potent immunostimulatory activity.
• Combination therapy is explored to overcome JQ-1's limitations and enhance efficacy.

Purpose of the Study:

• To evaluate the combined therapeutic efficacy of SZU-101 and JQ-1.
• To investigate the impact of combination therapy on tumor growth, metastasis, and the tumor microenvironment.
• To determine if dual targeting of innate and adaptive immunity improves antitumor response.

Main Methods:

• Murine breast cancer (4T1) and melanoma models were used.
• Mice received intratumoral (i.t.) SZU-101 and intraperitoneal (i.p.) JQ-1 combination therapy.
• Tumor growth, metastasis, immune cell populations (TAMs, CD8+ T cells), and PD-L1 expression were analyzed.

Main Results:

• Combination therapy significantly suppressed tumor growth and metastasis in both injected and uninjected sites.
• The treatment increased the M1/M2 ratio in tumor-associated macrophages (TAMs).
• PD-L1 expression was decreased, and activated CD8+ T cell recruitment into the tumor microenvironment (TME) was promoted.

Conclusions:

• Combination therapy with SZU-101 and JQ-1 demonstrates superior antitumor efficacy compared to monotherapy.
• This approach effectively modulates the immune microenvironment, enhancing adaptive anti-tumor immunity.
• The novel combination therapy shows promise for treating various cancers.