The FDA has granted Orphan Drug designation to a new type of myeloma therapy called an Antibody Redirecting Molecule (ARM) targeting CD38. The orphan drug designation approval is provided to diseases that affect fewer than 200,000 people in the United States and it helps accelerate clinical development. It also provides a longer period of exclusive marketing if the drug becomes approved. 

The anti-CD38 therapy is called KP1237 and is being developed by Kleo Pharmaceuticals. The antibody-redirecting molecules (ARMs) are bispecific, meaning they go after two targets. They are engineered with modular components that are readily interchangeable, giving the platform tremendous flexibility and rapid development times. ARMs are smaller than biologic therapies, which allows for enhanced tumor/tissue penetration, reduced immune system response (daratumumab can lower normal natural killer cell function), administration of higher dose levels with improved safety profiles, and the potential to develop oral drug administration. The ARM platform is also being used to redirect NK cell-based therapies to disease targets without chimeric engineering (the CAR T cell engineering process).

Two other myeloma treatments in today's armamentum target CD38 – daratumumab and isatuximab – but patients can become refractory to these drugs over time. The KP1237 product is being evaluated for two types of myeloma patients:

• Myeloma patients who relapsed after using daratumumab
• Newly diagnosed myeloma patients who are MRD positive following a transplant (in this case the drug will be combined with the patient's own natural killer cells)
• Use of KP1237 in combination with donor natural killer cells

Clinical trials for these three groups hope to open in late 2020.