Purespring bottles up $105M series B to bring kidney disease gene therapy to the clinic

London-based biotech Purespring Therapeutics plans to bring their kidney-tweaking gene therapy to the clinic with the help of a new £80 million (about $105 million) pool of series B cash.

The oversubscribed round was led by Sofinnova Partners, in collaboration with Gilde Healthcare, Forbion, British Patient Capital and founding investor Syncona, the company announced in an Oct. 9 release.

“Nearly one tenth of the world’s population, around 840 million people, suffer from chronic kidney disease,” CEO Julian Hanak said in the release. “Our novel treatment platform and deep understanding of kidney disease puts us in a position to stop, reverse and even cure kidney disease. The funds raised will allow us to bring our novel treatments to patients in the clinic.”

The funds will filter to drugs throughout Purespring’s pipeline, including lead asset PS-002, which is being developed for IgA nephropathy, a disease caused by a build-up of immunoglobulin A in the kidneys. Other programs target nephrotic syndrome and an undisclosed glomerular kidney disease.

Purespring will use the raise to start a phase 1/2 trial of PS-002 in IgA nephropathy, which commonly affects young adults, the company said in the release. About one third of patients lose their kidney function within five years and require a transplant or dialysis, according to Purespring.

Purespring’s approach uses adeno-associated viral vectors to bring healthy copies of genes to podocytes, specialized kidney cells that play a key role in the organ’s ability to filter blood. In a 2023 paper, the British outfit used their gene therapy to restore functional copies of the gene that codes for podocin, a critical podocyte protein, in a human cell line and in mouse models. A mutated podocin gene is a common cause of childhood genetic nephrotic syndrome, which leads to irreversible kidney failure that can be fatal without a kidney transplant.

Further preclinical results followed at the European Renal Association Congress in May, including more mouse data and data from pigs. Purespring used the swine to develop methods for translating the gene therapy to in-human studies, the company said in a May 24 release.

Purespring plans to present their IgA nephropathy data publicly for the first time at the American Society of Nephrology Kidney Week congress on Oct. 26.

There are currently no approved cell or gene therapies that treat kidney diseases. Many patients instead rely on dialysis or transplants, which both struggle with issues of equitable access. A kidney transplant cell therapy from Medeor Therapeutics, which combines a living donor’s cells with the recipient's, allowed more than half the participants in a 2023 phase 3 trial to stay off immunosuppressants for two years. Transplant patients normally need to take immunosuppressants for the rest of their lives.

Despite the phase 3 data, Medeor has suspended operations and is seeking potential acquirers who could finish filing the biologics license application asking the FDA to approve the gene therapy.