umbralisib

Drug Overview

Umbralisib (TG Therapeutics/Rhizen) is a novel phosphoinositide 3-kinase (PI3K) delta inhibitor that also selectively inhibits casein kinase-1 (CK1) epsilon. Expression of the PI3K delta isoform plays a role in B-cell development and function, and is often overactivated in B-cell malignancies. Umbralisib has a unique chemical structure that confers greater specificity to target sites and may produce equivalent or improved efficacy, along with a more favorable safety profile, in comparison to other PI3K inhibitors such as Zydelig (idelalisib; Gilead) or Copiktra (duvelisib; Verastem) in non-Hodgkin’s lymphoma.

Analyst Outlook

TG Therapeutics is developing its phosphoinositide 3-kinase (PI3K) inhibitor umbralisib as part of a combination with its in-house cluster of differentiation (CD)20-targeted antibody, ublituximab. The combination is being evaluated in the Phase II/III UNITY-NHL trial (ClinicalTrials.gov identifier: NCT02793583) for the treatment of relapsed or refractory non-Hodgkin’s lymphoma (NHL) patients, including diffuse large B-cell lymphoma (DLBCL) patients. The combination has demonstrated early signs of efficacy, but significant adverse events potentially tied to PI3K inhibition, such as neutropenia, remain a concern. As such, umbralisib’s uptake may be limited by its side-effect profile, the potentially high cost of a combination regimen with ublituximab, and strong forecasted competition from approved regimens and several late-phase competitors targeting the relapsed or refractory patient segment.