Kezar adds $50M to its funding tally for immunoproteasome drug

Fresh from a successful phase 1 trial for its lead asset, Kezar Life Sciences has closed a $50 million second-round funding that will help propel the autoimmune disease candidate into the next stage of testing.

It's been two years since the San Francisco-based start-up came out of stealth mode and raised $23 million in Series A funding to help develop KZR-616, the lead candidate in a family of drugs which are designed to treat diseases of the immune system by modulating the body's natural disposal of proteins.

The company's technology was discovered at Proteolix, a firm bought by Onyx that was subsequently acquired by Amgen which licensed it to Kezar.

Like Onyx's blockbuster cancer treatment Kyprolis (carfilzomib) the drug targets the proteasome, a system used by the body to degrade faulty or unneeded proteins. However, in contrast to Kyprolis and other proteasome inhibitors such as Takeda's Velcade (bortezomib), KZR-616 selectively targets only one portion, dubbed the immunoproteasome, which is thought to be involved with anti-inflammatory activity.

The phase 1 trial in 82 subjects identified multiple doses that dampened down the immunoproteasome to a level Kezar thinks should be clinically relevant, and showed that KZR-616 was well-tolerated with repeat dosing.  It is the first trial to be carried out in a selective immunoproteasome inhibitor, according to Kezar.

The company's chief scientific officer Chris Kirk Ph.D. said KZR-616's selectivity is designed to sidestep the side effects seen with Kyprolis and Velcade, adding that hypothesis is "exhibited by the early safety findings from this study."

"These initial clinical trial results demonstrate that KZR-616 is achieving the desired levels of immunoproteasome inhibition that correlate with anti-inflammatory activity seen in laboratory models," he said.

Kezar will reveal more details at the American College of Rheumatology (ACR) meeting in November, and will now press on with a phase 1b trial of the drug which is expected to enroll up to 40 patients with autoimmune disorders. It is eyeing several autoimmune disease indications for the drug, including rheumatoid arthritis, systemic lupus erythematosus and multiple sclerosis.

The new fundraising was led by Cormorant Asset Management and Morningside Venture, and Cormorant founder Bihua Chen will join Kezar's board.