US-based biopharmaceutical firm TG Therapeutics has initiated a new triple therapy clinical trial combining two of its experimental drugs, TG-1101, a glycoengineered anti-CD20 monoclonal antibody, and TGR-1202, a PI3K delta inhibitor, with the marketed BTK-inhibitor, ibrutinib (Imbruvica).
The trial seeks to evaluate the drugs in the treatment of patients with chronic lymphocytic leukemia (CLL) and other b-cell malignancies.
According to the company, the initiation of this trial marks the first time that a BTK-inhibitor and a PI3k delta inhibitor have been used in combination with each other in patients.
TG Therapeutics executive chairman and interim CEO Michael Weiss said: "Our mission has been and continues to be to develop novel combination therapies for the treatment of B-cell malignancies that can provide better patient outcomes without the use of harsh chemotherapies.
"We believe that to achieve this goal, combinations of multiple targeted agents will be required, and we plan to continue to be the leader in exploring novel combinations exploiting a variety of mechanisms.
"The start of today's triple therapy study marks the beginning of the next level of exploration and our commitment to patients living with this disease as well as demonstrates the speed at which we can move forward novel combinations."
The new trial will use fixed doses of TG-1101 and ibrutinib, and will provide for dose escalation of TGR-1202.
Led by Dr Susan O'Brien and Dr Nathan Fowler at MD Anderson, and Dr Julie Vose and Dr Matt Lunning of University of Nebraska, the trial will be run as a component of the previously announced and on-going Phase I trial of the combination of TG-1101 and TGR-1202.
Preliminary data from the Phase I trial of TG-1101 and TGR-1202 showed that the combination was well-tolerated at the doses tested to date.
The Phase I trial showed that preliminary signs of efficacy in high-risk CLL patients were encouraging, with four out of five patients from the CLL cohort achieving a partial response at first assessment and the fifth patient achieving stable disease with a nodal reduction of nearly 45% awaiting a second efficacy assessment.
In June, the company reported preliminary data from an ongoing study using the combination of TG-1101 plus ibrutinib, where the combination appeared to be well-tolerated with minimal grade 3/4 events observed, and significant efficacy demonstrated with ten out of ten patients achieving a complete or partial response.
Image: Wright's stained peripheral blood smear showing chronic lymphocytic leukemia (CLL). Photo: courtesy of Bibi Saint-Pol.