Kyowa Kirin’s Treatment for a Rare Cancer Disorder Approved by European Commission

On August 19, Kyowa Kirin announced the European Commission (EC) approved CRYSVITA® (burosumab) for the treatment of Tumor-Induced Osteomalacia (TIO). The decision comes after two Phase 2 trials showed the medicine’s efficacy and safety in treating this rare cancer disorder. 

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What is TIO, and what are its treatments?

TIO is a rare disorder caused by tumors producing too much of a protein known as Fibroblast Growth Factor 23 (FGF23). FGF23 regulates the amount of phosphorus in the body. With too much produced, the body excretes excess phosphorus through urination. This leads to a low level within the bloodstream, a condition known as hypophosphatemia. Due to hypophosphatemia, the body cannot absorb vitamin D as easily. This leads to a condition known as osteomalacia, which is the softening of bones, along with muscle weakness. 

Currently, the primary treatment for TIO is surgical removal. However, detecting small tumors is difficult. In addition, due to the rarity of TIO (affecting approximately 500-1000 people in the US), there are no standardized guidelines for treatment. 

However, CRYSVITA cuts out the need for surgery. The antibody inhibits the action of FGF23, bringing phosphorus levels back to normal. With the levels of ordinary phosphorus restored, the body no longer excretes an excess amount, leading to remedying the symptoms caused by the tumors. 

The EC’s approval follows the FDA’s Earlier this year 

The EC already approved CRYSVITA to treat X-Linked Hypophosphataemia (XLH). XLH is another rare disease functioning very similarly to TIO. However, rather than its excess production of FGF23 linked to tumors, a genetic disorder causes the increase in protein. 

In addition, two Phase 2 clinical trials proved CRYSVITA’s efficacy and safety in TIO patients. One of the studies, UX023T-CL201, found that 33% of fractures detected at the start healed by week 144. In addition, it found that CRYSVITA possessed a safety profile consistent with improvements in phosphate metabolism and osteomalacia.

Due to the studies and the EC’s prior approval, CRYSVITA gained approval for treating TIO. The EC’s decision follows the FDA’s approval of the treatment for this rare cancer disorder in June 2020. 

On the EC’s decision, Professor Ralf Oheim, Department of Osteology and Biomechanics at University Medical Center Hamburg, said, “The approval by the European Commission is a very welcome milestone for those living with TIO that cannot be cured by complete surgical resection. With the challenges faced by those living with TIO and those treating it, the unmet need in TIO has been clear for a long time and today’s decision will help support those living with TIO and those healthcare professionals supporting them address such unmet need.”

Now, patients diagnosed with this rare cancer disorder have a non-surgical option. CRYSVITA opens the possibility of eliminating the root cause of TIO and other bone weakening disorders like it. 

Author

Max Heirich