Data from two mid-stage studies show HI-Bio’s investigational therapy felzartamab lowers pathogenic antibody titers in patients with primary membranous nephropathy (PMN).
Pictured: Doctor holding model of kidney/Shidlovski/iStock
Data released Tuesday from two mid-stage studies show HI-Bio’s investigational therapy felzartamab lowers pathogenic antibody titers in patients with primary membranous nephropathy (PMN), a rare, kidney-specific autoimmune disease.
Between the two studies, M-PLACE and NewPLACE, the former recorded better therapeutic potential for felzartamab. Patients treated with a nine-dose, five-month course of HI-Bio’s PMN hopeful saw a more durable reduction in anti-PLA2R (aPLA2R) autoantibodies than NewPLACE participants, who were given two- and five-dose regimens of felzartamab.
In M-PLACE, felzartamab induced a median 45% decrease in aPLA2R levels as early as one week after treatment initiation. Deep response, defined as a more-than 50% drop in aPLA2R levels, was reported in most patients at six months.
After one year, felzartamab maintained or deepened its effects in most of the patients who showed initial treatment response.
The therapy also showed robust reduction of aPLA2R titers regardless of baseline levels, including in patients at-risk of severe disease and progression, as indicated by high baseline concentrations of the pathogenic antibody.
Following felzartamab treatment, M-PLACE participants experienced improvements in serum albumin levels and proteinuria, which suggests the candidate could also help the kidneys recover. Moreover, even patients who had previously been unresponsive to cyclophosphamide and anti-CD20 treatments like Genentech’s Rituxan (rituximab) achieved proteinuria remission.
As for safety, both studies found felzartamab to be generally well-tolerated, with most treatment-emergent adverse events being mild or moderate in severity. Overall, four patients dropped out due to side effects related to treatment with felzartamab.
What Happens Next
With these results in hand, the company plans to take felzartamab into late-stage development, Travis Murdoch, M.D., CEO of HI-Bio, said in a statement. The company also intends to present data and analysis from M-PLACE and NewPLACE at an upcoming medical conference.
Typically diagnosed between 40 and 50 years of age, PMN is a rare and autoimmune kidney disease that affects the glomeruli, making them inflamed and unable to efficiently filter protein out of the urine. Worldwide, PMN is a leading cause of nephrotic syndrome.
There are currently no approved treatments for PMN. Patients are typically managed with off-label drugs, immunosuppressive treatments, B-cell-depleting therapies and supportive care. Aside from excessive toxicity, many patients are unresponsive to these approaches and either relapse or do not reach remission.
About 80% of PMN cases are thought to be caused by high levels of the aPLA2R autoantibody, according to the company’s press release. Felzartamab addresses this by targeting CD38, a protein commonly expressed on the surface of mature plasma cells, which are responsible for producing the pathogenic autoantibody.
This mechanism of action allows felzartamab to selectively block CD38+ plasma cells without affecting other plasma cell populations, which could lead to therapeutic potential in other autoantibody-mediated conditions. In line with this, HI-Bio is also studying felzartamab in immunoglobulin A nephropathy.
Tristan Manalac is an independent science writer based in metro Manila, Philippines. He can be reached at tristan@tristanmanalac.com or tristan.manalac@biospace.com
