Two kidney transplant patients who received a stem cell therapy developed by Talaris Therapeutics were able to come off all immunosuppressant drugs within a year, without any evidence of graft rejection.

The first findings from Talaris phase 3 trial of the cell therapy called FCR001 suggest it may be possible to eliminate the need entirely for patients to take what may be dozens of tablets daily after organ transplants, according to the US biotech.

While still preliminary, the experience with the two patients back up Talaris hope that giving a one-shot dose of FCR001 the day after an organ transplant could stimulate immune tolerance in the recipient, and avoid the side effects of current drug treatments such as infections, heart disease, and some forms of cancer.

The companys approach relies on administering haematopoietic stem cells from the individual who donated the organ, in order to generate what Talaris refers to as chimerism, with both donor and recipient cells present in the bone marrow. That allows the immune system to see the transplanted organ as self rather than foreign.

The first two recipients in Talaris FREEDOM-1 phase 3 trial had received FCR001 at least 12 months earlier, and showed stable kidney function, according to Talaris.

A larger group of five patients who were at least three months from the cell therapy maintained more than 50% chimerism in their T cells, which the biotech said was a sign of long-term, immunosuppression-free tolerance to the donated kidney in its phase 2 trials.

The FREEDOM-1 results reported at the American Society of Nephrology (ASN) meeting this week were accompanied by updated results from Talaris phase 2 study, in which all 26 patients originally weaned off immunosuppressants have continued to remain off them without rejecting their donated kidney.

Some transplant patients treated with Talaris therapy in earlier trials have now been off all immunosuppression for more than 12 years without signs of kidney rejection.

Talaris intends to enrol 120 subjects into the phase 3 trial, which is scheduled to generate results in 2023.

Earlier this year, Talaris raised $150 million via a Nasdaq listing that will be used to take FCR001 through the phase 3 programme in organ transplantation and as a treatment for rare autoimmune disease scleroderma.

It also recently started a phase 2 trial of the cell therapy to see if it is able to induce immune tolerance to a transplanted kidney in patients who received the transplant from a living donor up to a year prior to administration of FCR001.

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Talaris therapy ends need for immune drugs in transplant patients - - pharmaphorum