FDA withdraws cancer drug approval after finding possible higher death rates

The US Food and Drug Administration has rescinded its approval of TG Therapeutics’ Ukoniq (umbralisib) after a clinical trial found patients on the cancer drug may have a higher mortality rate. The news comes a month and a half after the company voluntarily pulled the drug from market for the same reason.

On 1 June, the FDA issued a safety communication that it was withdrawing approval of Ukoniq which had been approved to treat marginal zone lymphoma (MZL) and follicular lymphoma (FL). After reviewing data from the UNITY phase III clinical trial which was evaluating the drug’s safety and efficacy as a treatment for chronic lymphocytic leukemia (CLL), the agency said it found patients on the drug had a higher mortality rate.

“The results showed a possible increased risk of death in patients receiving the combination of Ukoniq and the monoclonal antibody compared to the control arm,” the FDA said. “Those receiving the combination of Ukoniq and the monoclonal antibody also experienced more serious adverse events than those in the control arm.”

“The UNITY trial was conducted in CLL patients, which is not an approved use but rather a use of this drug that is being studied; however, we believe these findings have implications for its approved uses for MZL and FL,” the agency added. “In addition, clinical trials of other medicines in the same PI3 kinase inhibitor class as Ukoniq have shown similar safety concerns.”

The monoclonal antibody in question is TG Therapeutic’s ublituximab. The drug is being evaluated separately in another clinical trial as treatment for patients with relapsing forms of multiple sclerosis. While the company had hoped to get a decision from the FDA on ublituximab by 28 September, the company announced on 31 May the agency had extended the Prescription Drug User Fee Act (PDUFA) goal date for the biologics license application (BLA) to 28 December.

In 2016, the FDA issued a similar safety alert for Gilead’s PI3 kinase inhibitor Zydelig (idelalisib) which too showed to have higher mortality rates in clinical trials where patients were being treated for chronic lymphocytic leukemia, small lymphocytic lymphoma and indolent non-Hodgkin lymphomas.

While the FDA continues to review the UNITY clinical data, the agency is telling health care providers to stop prescribing the drug and switch patients to alternative therapies. In instances where patients are benefitting from Ukoniq, TG therapeutics can still provide the drug through the FDA’s expanded access pathway.