Actinium Pharmaceuticals Receives FDA Request For Additional Studies On Leukemia Treatment

On Monday, the FDA determined that Actinium Pharmaceuticals, Inc.’s ATNM Phase 3 SIERRA trial is not adequate to support a Biologics License Application (BLA) filing for Iomab-B despite its statistically significant primary endpoint.

The company announced a regulatory update on its planned BLA Biologics License Application seeking approval for Iomab-B in patients with active relapsed or refractory acute myeloid leukemia (r/r AML).

The FDA has advised Actinium to conduct a head-to-head study to evaluate allogeneic bone marrow transplant (BMT) using Iomab-B plus a reduced intensity conditioning regimen of fludarabine and total body irradiation (Flu/TBI) versus allogeneic BMT using reduced intensity conditioning comprised of cyclophosphamide plus Flu/TBI, a difference from the SIERRA trial, which had allowed physician’s choice of salvage therapies and heterogenous conditioning regimens in the control arm.

Additionally, the proposed new study will not allow patients to crossover from the control arm, which was allowed in the SIERRA trial and confounded the overall survival analysis in the intent-to-treat (ITT) patient population, as nearly 60% of patients crossed over from the control arm.

In February 2023, Actinium announced that the SIERRA trial met the primary endpoint with statistical significance as 22% of patients (13/76) on the Iomab-B arm achieved dCR compared to 0% of patients (0/77).

The SIERRA trial was conducted in accordance with guidance from the FDA’s End of Phase 2 meeting, which stated that positive results for dCR as the primary endpoint would be acceptable to support an Iomab-B BLA filing.

SIERRA did not meet the secondary endpoint of overall survival on an intent-to-treat basis analysis due to the high crossover rate, with nearly 60% of control arm patients receiving Iomab-B followed by a BMT.

Upon concluding its interactions with the FDA, Actinium will seek a strategic partner for Iomab-B in the U.S.

Price Action: ATNM stock is down 74% at $1.59 at last check Monday.

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