NantKwest Announces Updated Clinical Results for Nanatinostat (VRx-3996), a Novel HDAC Inhibitor Being Developed in Partnership with Viracta Therapeutics

NantKwest Inc. (Nasdaq:NK) announced today that its strategic partner Viracta Therapeutics presented updated clinical data on its HDAC inhibitor, nanatinostat (VRx-3996) at the Annual Meeting of the American Society of Clinical Oncology (ASCO) in Chicago, IL, from May 31^st – June 4^th, 2019.

In April 2017, NantKwest announced that it was the lead investor in Viracta’s Series B financing round. Concurrent with the financing, NantKwest secured an exclusive license with commercialization rights to nanatinostat for use in combination with natural killer (NK) cell therapies, including NantKwest’s NK cell platforms.

Nanatinostat is a Class 1 histone deacetylase (HDAC) inhibitor currently in phase Ib/II clinical trials (NCT03397706). In preclinical studies, nanatinostat has been shown to reactivate silenced transgenes in tumor cells thereby turning them into preferential targets for NK cell killing, while also serving to broadly stimulate a patient’s immune system, offering the potential for improved clinical responses in cancer patients.

The activity of HDAC inhibitors are believed to be based on the upregulation of natural killer group 2D (NKG2D) ligand expression on cancer cells, which serve as “eat-me” signals for NK cells and can drive NK proliferation, activation and cancer cell killing.

NantKwest is preparing to initiate clinical trials that include nanatinostat in combination with its haNK and t-haNK cell therapy platforms, which we believe will work synergistically to enhance the efficacy of the company’s NK cell therapies and further distinguish us in the market.

Interim results presented at the 2019 annual ASCO meeting from the phase Ib portion of the ongoing phase Ib/II clinical trial of nanatinostat was in combination with the antiviral valganciclovir for the treatment of relapsed/refractory Epstein Barr Virus (EBV)-associated lymphomas. Three doses of the combination were evaluated with responses seen at all dose levels. Both drugs are taken orally and can be administered in an out-patient setting.

EBV-associated cancers are known to be an extremely difficult cancer to treat. Early clinical data with the combination of nanatinostat and anti-viral therapy in EBV-associated lymphoma from the phase Ib/II study has provided encouraging efficacy signals. Currently, there are no approved treatments for EBV-associated lymphomas that specifically target the virus.