Bioabsorbable polymer spacer balloon company BioProtect has announced the initial closing of its Series D equity financing round at $13m.

BioProtect’s pipeline of spacing products help improve outcomes in radiotherapy and interventional oncology procedures, as well as in aesthetics and general surgery.

Major investors in the Series D round include the family office of Consensus Business Group chairman Vincent Tchenguiz, which committed $7m. Prominent medtech investor Accelmed Ventures II and Korean financial firm KB Investments contributed a joint $6m.

The money will go towards financing the ongoing multicentre FDA clinical trial of BioProtect’s lead product, the ProSpace balloon spacer, and expanding its technology platform. ProSpace protects prostate cancer patients undergoing radiation therapy.

Recent radiotherapy innovations have enabled larger doses of radiation to be delivered in fewer sessions. Prostate radiation therapy has been historically limited by concerns over the risk of rectal toxicity following radiotherapy.

The ProSpace balloon spacer helps reduce this risk by pushing the prostate away from the rectum. The spacer is injected with saline and provides a gap of over 1.5cm between the two organs, which is absorbable under a computed tomography scan. It is gradually absorbed after the radiation therapy is completed.

Tchenguiz said: “We have been supporting BioProtect for a long time, watching it succeed. We believe its technology offers strong value that would help the market’s growth. We also recognise the strength of the platform and are keen to work with the company to continue and grow it.”

According to BioProtect, its future pipeline could represent a $4bn opportunity, with additional applications for cervical, pancreatic and breast cancer radiation therapies. BioProtect musculoskeletal spinout Orthospace was acquired by Stryker last year for a reported $220m.

BioProtect CEO Gil Rosen said: “The capital will allow us to focus on our most important mission, obtaining FDA approval. As the radiotherapy market continues to offer shorter, more accurate radiotherapies, BioProtect is on a mission to offer as many cancer patients as possible safer radiation treatment.”