Phase 1 Actimab-M Trial at Baylor Recruiting Heavily Treated Myeloma Patients

Multiple myeloma patients who received at least three prior lines of therapy and whose cancer expresses the CD33 molecule may enroll in the recently opened Phase 1 clinical trial at Baylor Scott & White Research Institute, part of Baylor Health Care, in Dallas, Texas.

The open-label, single-arm trial (NCT02998047) will evaluate the safety and effectiveness of Actimab-M, a CD33 targeting antibody linked to the radioactive compound actinium 225. The therapy was developed by Actinium Pharmaceuticals.

“Treatments for multiple myeloma have progressed tremendously in the past decade,” Yair Levy, MD, director of hematolgic malignancies research at Baylor University Medical Center at Dallas, said in a press release. “Unfortunately most patients’ cancer recurs with current treatments and the disease is considered incurable at this time.”

“We are examining the genetic behavior and tendencies of this cancer to hopefully identify new targets for treatment for these patients who experience disease progresses on our current therapies,” said Levy, who is also the principal investigator of the trial. “This is the first trial in the U.S. to open using this method of treatment, taking bench research into the clinic. I am excited to lead the development of this novel approach.”

CD33 is a protein found in normal blood cells and those of certain blood cancers, particularly acute myeloid leukemia. But studies have shown this protein is also found in 25% to 35% of multiple myeloma patients, and is especially evident in those with relapsed or refractory disease.

“Interestingly, we have found aberrant expression of this marker on some lymphoid cancers, including myeloma,” Levy said. “Research has shown its presence in cancer cells of 25 to 35 percent of all multiple myeloma patients, making it a possible target for treatment. In addition, it also predicts for a more aggressive course of disease.”

The Phase 1 trial is a dose-escalation study, designed to assess the safety and efficacy of Actimab-M in up to 12 myeloma patients whose disease progressed despite three prior treatment regimens, or who are refractory to QUAD (caflizomib, lenalidomide, pomalidomide, dexamethasone) therapy.

Patients will be given an infusion of of Actimab-M on day 1 of each 42-day cycle, for eight cycles as a starting dose. If this dose shows a tolerable safety profile, a second larger dose on day 1 of up to four, 42-day cycles, will then be tested. If, however, the starting dose level results in dose limiting toxicity in at least two of the three patients in that group cohort, a lower dose level will be explored.

After the dose escalation part is completed, three additional patients will be treated with the highest established dose to confirm it is the maximum tolerated dose. An additional primary endpoint is to determine the number of treatment-emergent adverse events.

Secondary endpoints include measures of objective response rates, progression-free survival, and overall survival.