HI-Bio's expectations elevated after pair of phase 2 readouts bolster autoimmune ambitions

Human Immunology Biosciences believes its early investment in an immunology asset is beginning to pay off, reporting positive phase 2 data of a kidney disease treatment less than six months after the company was unveiled. 

Felzartamab, which the biotech licensed from MorphoSys, showed a durable reduction in an important biomarker when used as a treatment for a rare kidney disease called primary membranous nephropathy (PMN), HI-Bio announced Tuesday. The data tee up a registrational study, although the timing is contingent on discussions with regulators. 

“I think it's the first view of the articulation of a strategy that we've been pursuing for the last couple of years,” CEO Travis Murdoch, M.D., said in an interview with Fierce Biotech. 

Felzartamab is a monoclonal antibody designed to deplete CD38+ plasma cells, which the company said are believed to drive PMN through the production of anti-PLA2R (aPLA2R) autoantibodies. The therapy was tested in two open-label phase 2 trials, including M-PLACE, which assessed nine doses administered across nine months in 31 adults with aPLA2R-positive PMN. The other study, dubbed NewPLACE, comprised two treatment arms—two doses over two weeks and five doses over two months, respectively—across a total of 24 participants. 

HI-Bio reported that the most durable reduction in aPLA2R autoantibodies came in the nine-dose trial, with a median reduction of 45% after the first week. The company found that the reduction in autoantibody levels occurred regardless of initial aPLA2R levels. Patients in the trial also reported reductions in proteinuria, a protein in the urine that, in high levels, can be indicative of poor kidney function. 

Murdoch acknowledged that the company was tempering expectations given that neither trial was placebo-controlled, but he underscored the value in the “firm” endpoints selected. 

“I think from the point of view of treatment effects, that's what gives us greater excitement than if we were looking at a clinical endpoint that could have more source of confounding,” he said. 

Felzartamab was generally well tolerated with four patients across both trials discontinuing the drug due to treatment-related adverse events. A previous poster on the M-PLACE trial reported that three of the discontinuations were due to hypersensitivity, neutropenia and an infusion-related reaction (IRR), respectively. The cases of hypersensitivity and IRR resolved within a day while the case of neutropenia took more than a month to resolve. 

The phase 2 results are a welcome reassurance that HI-Bio is on the right path after the company emerged from stealth mode in November 2022 with $120 million in financing plus felzartamab and another near-clinical-stage asset, HIB210, in its pipeline.

Now, the company is making phase 3 plans for felzartamab. But Murdoch wouldn’t rule out pursuing the FDA's accelerated approval route with a focus on reduction in proteinuria levels, saying that HI-Bio will “need to speak to the agency and really get their feedback.” 

“We think this is a targeted therapy that we think is going to be very favorable from a tolerability point of view and where we're seeing activity,” he said. 

The focus now is maximizing the potential of felzartamab. The med is already in phase 2 trials as a treatment for IgA nephropathy and antibody-mediated transplant rejection, and Murdoch teased other areas where off-label CD38-targeting therapies have been used, though he didn’t specify diseases. 

As for HIB210, which was also licensed from MorphoSys, Murdoch said the company plans to launch a phase 1 trial this year in healthy volunteers. The company is eyeing anti-neutrophilic cytoplasmic autoantibody-associated vasculitis as one potential disease area but is looking at other indications as well.