Gene Therapy for B-Cell Acute Lymphoblastic Leukemia

VNX-101 is an investigational adeno-associated virus (AAV) gene therapy developed to express a secreted anti-CD19/anti-CD3 scFv diabody (termed GP101). GP101 binds both cluster of differentiation (CD)19 and CD3, inducing T-cells to kill both benign and malignant B-cells. Following a single intravenous (IV) infusion, the vector induces the liver and key tissues to continuously secrete GP101 into the bloodstream, resulting in long-term, consistent serum levels of GP101. Potential advantages of VNX-101 over autologous CAR-T therapy include it is off-the-shelf, provides a gentle onset of action, does not require lymphodepletion chemotherapy, engages all T-cells continuously (including those freshly produced from the bone marrow), and utilizes highly efficient signaling through the native T-cell receptor.

In this 2-part study, dose-finding data from Part 1 of the study (n=12 patients with marrow blasts <5%) will be used determine the dose for Part 2 in patients at higher disease burden (marrow blasts <50%). Part 1 is a dose-finding PK study in adults ≥18 years old designed to determine the minimal dose that achieves target PK serum levels of GP101 at steady state (8-week timepoint) without dose-limited toxicities, defined as the recommended Part 2 dose (RP2D). Prior to VNX-101 dosing, subjects may undergo standard of care chemotherapy to meet dosing criteria. Part 2 (n=14) will be opened following data safety monitoring board review of Part 1 data and is designed to determine the safety and pharmacokinetics (PK) of VNX-101 at the RP2D in a broader array of subjects with higher leukemic burden (i.e. bone marrow blasts <50%). The age range for Part 2 will be expanded to include subjects ≥13 years old. Patients will be followed for safety and efficacy up to 5 years post VNX-101 dosing. Long-term follow-up assessments for safety will be conducted for 6 to 15 years post VNX-101 dosing.