Astellas, bullish on XLMTM, inks KateTx deal

June 8, 2023

Astellas Pharma will license and advance a novel gene therapy from Kate Therapeutics for a debilitating muscle disorder — the same indication where the Japanese drugmaker has previously failed.

California-based KateTx's asset, KT430, is a preclinical next-generation gene therapy that delivers a functional copy of the MTM1 gene via a novel MyoAAV capsid to treat X-linked myotubular myopathy (XLMTM). XLMTM is a serious, life-threatening, rare neuromuscular disease characterized by extreme muscle weakness, respiratory failure and early death.

This is Astellas' second attempt to find a treatment for the disease. Back in 2019, following an emotional plenary presentation of phase 1/2 data at ASGCT by Audentes Therapeutics, Astellas paid $3 billion to acquire Audentes.

Astellas launched the ASPIRO trial to study the gene therapy, AT132, in XLMTM. The trial was paused in 2020 after three patients suffered liver failure and later died. At the time, the treatment was being administered at two different doses. Because all of the patients who fell ill were in the higher-dose group, Astellas was later given the FDA’s blessing to restart the trial using only the lower dose.

Then, in September 2021, Astellas announced that a fourth patient — who had received the lower dose — had abnormal liver tests. The patient later died and the trial was discontinued. 

But Astellas doesn't seem ready to give up on treating XLMTM and KateTx says its novel technology platforms address the key limitations of current gene therapies and can improve both efficacy and safety.