14 January 2021 - - The US Food and Drug Administration has cleared US-based cell therapy company Vor Biopharma's Investigational New Drug application for VOR33, an eHSC therapy candidate being developed for the treatment of acute myeloid leukemia, the company said.

The company plans to initiate a Phase 1/2a clinical trial for VOR33 in the first half of this year.

VOR33, consisting of hematopoietic stem cells that are engineered to lack the CD33 protein, is a cell therapy candidate intended to replace the standard of care in hematopoietic stem cell transplant settings for patients with AML who are at high-risk for relapse.

The Phase 1/2a trial is expected to enroll patients with CD33-positive AML who are at high risk of relapse. The primary goals of the trial are to evaluate tolerability and feasibility of the VOR33 stem cell transplant, with a focus on confirming that VOR33 can engraft normally.

Following engraftment, patients will be eligible to be treated with Mylotarg, an FDA approved CD33-directed antibody drug conjugate therapy owned by Pfizer (NYSE: PFE), in order to potentially prolong leukemia-free survival and provide evidence that VOR33 protects against the myelosuppression that typically accompanies treatment with Mylotarg.

VOR33 is Vor's lead product candidate, consisting of eHSCs that we have engineered to lack the protein CD33, and is designed to replace the standard of care in transplant settings for patients suffering from AML and potentially other hematologic malignancies.

Once the VOR33 cells have engrafted, we believe that patients can be treated with anti-CD33 therapies, such as Mylotarg or, if approved by the FDA, Vor's in-licensed CD33 chimeric antigen receptor T-cell (CAR-T) therapy candidate, with limited on-target toxicity, leading to durable anti-tumor activity and potential cures.

In preclinical studies, we have observed that the removal of CD33 provided robust protection of VOR33 eHSCs from the cytotoxic effects of CD33-directed therapies, yet had no deleterious effects on the differentiation or function of hematopoietic cells.

Vor Biopharma is a clinical-stage cell therapy company that aims to transform the lives of cancer patients by pioneering eHSC therapies to create next-generation, treatment-resistant transplants that unlock the potential of targeted therapies.