REGENXBIO Inc. has announced that enrollment has completed at dose level 2 of the Phase I/II AFFINITY DUCHENNE® trial of RGX-202, an investigational gene therapy product for the potential treatment of Duchenne. RGX-202 utilizes a novel adeno-associated virus (AAV8) to transport a shortened version of the dystrophin gene (micro-dystrophin) that may provide benefit in place of the missing full-length dystrophin protein. The company also reported additional interim safety and efficacy data in the study, which enrolled patients with Duchenne ages 4 to 11 years old:

• The company shared that RGX-202 has been well tolerated with no drug-related serious adverse events in five patients, aged 4.4 to 12.1 years at dose level 1 (1×10¹⁴ genome copies (GC)/kg body weight) and dose level 2 (2×10¹⁴ GC/kg body weight). 
• Additionally, initial biomarker data in a third patient, aged 6.6 years, who received RGX-202 at dose level 1, shows that RGX-202 micro-dystrophin expression was measured to be 83.4% on Western blot compared to control at three months and a reduction from baseline in serum creatinine kinase (CK) levels of 93% was observed at ten weeks. 
• REGENXBIO indicated that these encouraging increases in expression of RGX-202 microdystrophin and reduction from baseline in serum CK levels support evidence of clinical improvement.

REGENXIO expects to make a pivotal dose determination in mid-2024. The company also expects to share initial strength and functional assessment data for both dose levels and the initiation of a pivotal trial in the second half of 2024.

Read REGENXBIO’s press release here.