Pirfenidone inhibits CCL2-mediated Treg chemotaxis induced by palbociclib and fulvestrant in HR+/HER2- breast cancer

Palbociclib plus fulvestrant has shown benefit in HR+/HER2- breast cancer; however, the combination upregulates CCL2 in tumor cells, which attracts Tregs and creates an immunosuppressive effect. To combat this, researchers administered pirfenidone and found that it inhibited Tregs by suppressing CCL2. They concluded that CCL2 inhibitors such as pirfenidone may be a viable approach for enhancing the antitumor effects of palbociclib plus fulvestrant in this patient population.