Roche-backed AveXis, the developer of a spinal muscular atrophy treatment, intends to issue 4.25 million shares priced between $19 and $21.

AveXis, a US-based gene therapy technology developer backed by pharmaceutical company Roche, set the range for its initial public offering at $19 to $21 yesterday.

The company plans to issue 4.25 million shares, which would put the size of the IPO between and $80.3m and $89.3m. If the IPO underwriters take up the option to buy an additional 637,500 shares that figure would increase to between $92.4m and $102.7m.

AveXis is working on gene therapy treatments for rare and…