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September 9, 2020 Bioscience

Kleo multiple myeloma drug earns ‘orphan’ status

Photo | Contributed Kleo Pharmaceuticals is located at 150 Munson St. in New Haven.

A drug being developed by New Haven’s Kleo Pharmaceuticals to treat the blood cancer multiple myeloma has been granted “orphan” status by the FDA.

The U.S. Food & Drug Administration awards “orphan” status to treatments for diseases affecting fewer than 200,000 people in the U.S., or for drugs that are not expected to recoup the costs of development and marketing, according to the agency.

The designation qualifies Kleo for incentives that include certain tax credits and a new drug application fee waiver. It also entitles Kleo to a period of market exclusivity after approval.

Kleo has described its lead drug, KP1237, as an antibody redirecting molecule, or ARM, that induces the body’s natural killer cells (a type of white blood cell) to recognize and destroy cancer cells. The platform is based on the research of Dr. David Spiegel, a chemistry professor at Yale. 

The drug, which targets an antibody known as C38, has been shown in animal studies to have fewer toxic side effects than existing treatments, according to Kleo.

The company is planning to begin human testing in two separate clinical trials later this year.

One trial will test the drug as a systemic therapy in multiple myeloma patients ineligible for stem cell transplant who failed to respond or who relapsed on previous treatments. 

The other trial will premix KP1237 with a patient’s own natural killer cells before administration and will focus on patients who show residual traces of the disease immediately following a stem cell transplant. 

The company is also planning a third trial, combining the drug with “off-the-shelf” natural killer cells, for early 2021. 

The American Cancer Society estimates there will be roughly 32,270 new cases of multiple myeloma diagnosed in the U.S. this year, and 12,830 deaths. 

Another Kleo drug, targeting COVID-19, scored a $5 million grant from the Bill & Melinda Gates Foundation in July.

Contact Natalie Missakian at

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