Class 1 HDAC Inhibitor

Entinostat is a selective, oral, once-weekly, class I HDAC inhibitor that has been studied in multiple solid tumors in combination with hormone therapy and several approved PD-1/PD-L1 antagonists.

Entinostat in combination with hormone therapy

Endocrine based therapy is a backbone of treatment with proven clinical benefits for women HR+, HER2- breast cancer. Over time, disruption of estrogen mediated signaling within the breast cancer cell results in acquired resistance to hormone therapy. Entinostat is thought to re-sensitize these cells to endocrine therapy.


Entinostat in combination with checkpoint therapy 

Class 1 HDACs have been shown to influence the anti-tumor immune response through down-regulation of immune suppressive cell number and function, increased antigen presentation on cancer cells and enhanced cytotoxic T cell activity.

In preclinical studies, entinostat demonstrated synergistic anti-tumor activity in combination with immune checkpoint inhibitors in multiple tumor models including lung, breast, colon, kidney and pancreatic cancers, suggesting a potential to further increase the ability of the patient’s T cells to attack the tumor.

Our phase 2 data from ENCORE 601 (testing entinostat in combination with pembrolizumab) in patients with NSCLC whose disease has progressed following treatment with an anti-PD-(L)1 and chemotherapy also indicate that patients with higher levels of a circulating cell called a classical monocyte may have better outcomes than those with lower levels.

We have deprioritized the development of entinostat, but maintain a license, development and commercialization agreement with Eddingpharm International Company Limited, or Eddingpharm, under which we granted Eddingpharm an exclusive license under our intellectual property rights to develop and commercialize entinostat in China and certain other Asian countries.