First Patient Dosed in Phase 1 Trial of P-BCMA-101 CAR T-Cell Therapy for Multiple Myeloma

The first patient has been dosed in a Phase 1 trial of P-BCMA-101, a new, more powerful type of CAR T-cell therapy to fight multiple myeloma, the therapy’s developer, Poseida Therapeutics, announced.

The trial (NCT03288493), which will test the safety and effectiveness of P-BCMA-101 in adult relapsed or treatment-refractory myeloma patients, continues to recruit patients at three U.S. locations: Denver, Colorado; Nashville, Tennessee; and Houston, Texas.

“P-BCMA-101 is a next generation CAR-T cell therapy designed to maintain very potent and durable activity against BCMA, an antigen target expressed on essentially every multiple myeloma cell,” Matthew Spear, chief medical officer at Poseida, said in a press release.

To produce CAR T-cells, researchers use a patient’s own T-cells that are collected from the blood and genetically engineered to find and destroy cancer cells.

In addition to targeting BCMA, or B-cell maturation antigen, P-BCMA-101 has several other potential advantages over previous CAR T-cell therapies. Instead of using a virus to genetically alter the cells, Poseida uses a technology called piggyBac, which is 100% pure.

P-BCMA-101 led to more effective responses in preclinical studies. The therapy has a high proportion of stem cell memory T cells, which results in the “unprecedented durability of response without re-administration of product in multiple preclinical studies,” the company said.

P-BCMA-101 also is believed to be safer than previous CAR T-cell therapies. It does not leave a footprint on exposed cells, and it is equipped with a safety switch, which means that if severe side effects occur, researchers can quickly eliminate or reduce the cells to counter the effect.

“P-BCMA-101 modified T-cells have shown the highest composition of stem cell memory T cells (Tscm) in a clinical program to date, which is of considerable interest as young T-cell subtypes such as Tscm’s have been correlated with high response rates in immuno-oncology,” Spear said.

The study will recruit about 40 patients, who will receive a single infusion of the cells and then be monitored for two years. Researchers will use escalating doses to determine the largest effective dose that patients can tolerate. These data will be used to select an appropriate dose for subsequent trials.

Patients will be monitored for side effects, and researchers will study how the treatment is processed in the body. They also will assess how effective the treatment is in triggering an anticancer response by measuring the scope and duration of responses, progression-free survival, and overall survival.

“This is a promising approach for an incurable disease where there is a significant need for new treatments that can benefit patients with relapsed and refractory disease,” Spear said.

For more information about the study, including contact details, see the trial’s website here.