Actinium Announces Positive Topline Results from Pivotal Phase 3 SIERRA Trial of Iomab-B in Patients With Active, Relapsed, or Refractory Acute Myeloid Leukemia


– Iomab-B achieved the primary endpoint of durable complete remission 6 months after initial complete remission after HCT with p-value

NEW YORK, October 31, 2022 /PRNewswire/ — Actinium Pharmaceuticals, Inc. (NYSE AMERICAN: ATNM) (Actinium or the Company), a leader in the development of targeted radiation therapies, today announced positive top results from the pivotal Phase 3 trial for its lead product candidate Iomab-B. The SIERRA (Study of Iomab-B in Elderly Relapsed or Refractory AML) trial was conducted in patients aged 55 or older with active disease (relapsed or refractory AML). The SIERRA trial is a randomized, multicenter, controlled study that compared Iomab-B as a conditioning regimen prior to bone marrow transplant (BMT) versus a control arm that enabled all current means of conventional care with intend to transplant these patients. The SIERRA trial met its primary endpoint of durable complete remission or dCR of 6 months after baseline remission after GMO in the Iomab-B arm versus the conventional care arm demonstrating statistical significance p

dr. Avinash DesaiChief Medical Officer of Actinium, added, “We are delighted that the randomized, controlled, multicenter, pivotal SIERRA trial has provided these results for patients who need new treatment options. Our goal is to increase access to BMT and improve patient outcomes with Iomab-B, and these early results point us in that direction given their statistical significance. We will continue to work on our Biologics License Application (BLA) submission to the US Food and Drug Administration (FDA) for approval of Iomab-B. On behalf of Actinium, I would like to thank the patients who took the plunge and enrolled in the SIERRA trial, their families and caregivers who supported them, and the researchers who contributed their efforts and advice to make this possible test. would not have been possible to obtain these results which will allow us to continue to develop Iomab-B.”

Sandesh SethChairman and CEO of Actinium, said: “This is an important step in the life cycle of Actinium and a testimony to the quality of our team who undertook a pioneering study in a population of patients considered largely unnecessary to treat. under resourced, their passion and perseverance has produced a clinically meaningful dividend. Our recently strengthened team is executing to enable our mission to disrupt the field of bone marrow conditioning with Iomab-B, first in r/AML r, then building on its robust previous clinical results in several hematological diseases. We look forward to sharing additional clinical data from the SIERRA trial by the end of the year.

About Iomab-B and the Pivotal Phase 3 SIERRA Trial

Iomab-B is a first-in-class targeted radiation therapy intended to improve patient access to potentially curative BMT by simultaneously and rapidly depleting blood, immune and bone marrow cancer stem cells that uniquely express CD45. Several studies have demonstrated increased survival in patients receiving GMO, however, an overwhelming majority of patients with blood cancers do not receive GMO because current approaches do not produce remission, which is required to switch to GMO, or are too toxic. Studied in over 400 patients, prior studies with Iomab-B have demonstrated near universal access to BMT, increased survival and tolerability in multiple clinical trials, including the recently completed pivotal Phase 3 SIERRA trial in patients with active disease (leukemic blasts >5%), relapsed or refractory acute myeloid leukemia (r/r AML) aged 55 years and over. The SIERRA trial produced superior positive results, meeting its primary endpoint of durable complete remission (dCR) of 6 months with statistical significance (p

The pivotal Phase 3 SIERRA (Study of Iomab-B in Elderly relapsed or refractory AML) study is a multicenter, randomized clinical trial of 153 patients, studying Iomab-B versus a physician-selected salvage therapy control group. Control arm options included chemotherapies such as cytarabine and daunorubicin and targeted agents such as a Bcl-2 inhibitor (Venetoclax), FLT3 inhibitors, and IDH 1/2 inhibitors. The SIERRA control arm reflects the actual treatment of patients with r/r AML with more than 20 single agents or combination of agents, as there is no standard of care for this patient population. Full patient enrollment data presented at tandem meetings on transplantation and cell therapy at April 2022 showed that 100% of patients receiving Iomab-B accessed GMO and were transplanted without delay. Iomab-B was also shown to be well tolerated given its targeted nature, consistent with its previous clinical data. The SIERRA trial recruited patients from 24 leading transplant centers in United States and Canada who perform more than 30% of BMT AML.

Developed at the Fred Hutchinson Cancer Research Center, a pioneer in the field of BMT, Iomab-B is backed by data in six disease indications, including leukaemias, lymphomas and multiple myeloma, which affect more than 100,000 patients every year. Actinium intends to pursue additional indications for Iomab-B beyond AML. Actinium also intends to pursue international regulatory approvals independently and through partnerships. In April 2022Actinium under European license, Middle East and the North African commercial rights for Iomab-B to Immedica AB, a wholly owned independent pharmaceutical company headquartered in Sweden. In exchange, Actinium received an initial payment of 35 million US dollars with the possibility of a supplement US$417 million in regulatory and commercial milestones and royalties of approximately twenty percent. Europe represents a business opportunity twice the size of United States by number of AML patients receiving GMO. Iomab-B has been granted orphan drug designation by the European Medicines Agency (EMA) and has received a positive scientific opinion from the EMA’s Committee for Medicinal Products for Human Use (CHMP) stating that the design of the Phase 3 SIERRA trial, primary endpoint and planned statistical analyzes are acceptable as the basis for a marketing authorization application.

About Actinium Pharmaceuticals, Inc.

Actinium Pharmaceuticals, Inc. is a clinical-stage biopharmaceutical company developing targeted radiation therapies to deliver anticancer radiation with cellular-level precision to treat patients with high unmet need. Actinium’s clinical pipeline is driven by targeted conditioning radiation therapies, which aim to selectively deplete a patient’s disease or cancer cells and certain immune cells prior to bone marrow transplantation (BMT), gene therapy or adoptive cell therapy, such as CAR-T, to allow engraftment of these transplanted cells with minimal toxicities. Our lead product candidate, I-131 apistamab (Iomab-B) has been studied in over four hundred patients in six disease indications including acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), acute lymphoblastic leukemia (ALL), Hodgkin’s lymphoma, non-Hodgkin’s lymphoma (NHL) and multiple myeloma in twelve clinical trials, including the pivotal Phase 3 study of Iomab-B in the SIERRA trial (Relapsed or Refractory Acute Myeloid Leukemia in the elderly) for BMT conditioning. Iomab-B targets CD45, a cell surface protein expressed on blood cancer cells, normal nucleated immune cells and bone marrow stem cells. Actinium has obtained exclusive worldwide rights to Iomab-B from the Fred Hutchinson Cancer Research Center, an award-winning institution that has pioneered the field of bone marrow transplantation. Data. Data from the pivotal Phase 3 SIERRA trial has been presented at several international medical conferences such as the American Society of Hematology (ASH) annual meeting with recent data submitted for presentation at this year’s meeting, the Tandem Meetings, Transplantation & Cellular Therapy Meetings of the American Society for Transplantation and Cellular Therapy (ASTCT) and the Center for International Blood & Marrow Transplant Research (CIBMTR), and the annual meeting of the Society of Hematologic Oncology (SOHO), where it received an honorable distinction in 2019. After the success of the first results, the company plans to publish a more complete set of results by the end of 2022 and is working towards a BLA filing in 2023. Iomab-ACT , I-131 apamistab at low dose, is being studied as a targeted conditioning agent in a Phase 1 study with CD19 CAR T-cell therapy with Memorial Sloan Kettering Cancer Center with a NIH funding. Iomab-ACT uses a lower dose of I-131 and is being developed to be a single-infusion, outpatient therapy that can cause patients to transiently lymphodeplete before receiving their CAR-T cell therapy. Actimab-A, our second most advanced product candidate, has been studied in approximately 150 patients with acute myeloid leukemia or AML, including ongoing combination trials with the CLAG-M chemotherapy regimen and venetoclax, targeted therapy. Actimab-A or lintuzumab-Ac225 is an actinium-225-based antibody radiation conjugate targeting CD33, a validated target in AML. Actinium is a pioneer and leader in actinium-225 alpha therapies with a state-of-the-art technology platform comprising over 195 patents and patent applications, including methods for producing the radioisotope AC-225. Our technology and expertise have enabled collaborative research partnerships with Astellas Pharma, Inc. for theranostics of solid tumors, with AVEO Oncology Inc. to create radiation therapy targeting Actinium-225 HER3 for solid tumors, and with EpicentRx, Inc. to create combinations of targeted radiation therapy with their novel clinical-stage small molecule CD47-SIRPα inhibitor. More information is available on the Actinium website:

Hans Vitzthum
LifeSci Advisors, LLC
[email protected]
(617) 430-7578

SOURCE Actinium Pharmaceuticals, Inc.


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