Handok (Chairman & CEO Young-jin Kim, Vice President Jin-ki Paik) and Genexine (CEO Young-chul Sung) announced Phase II clinical trial results for the long-acting recombinant human growth hormone GX-H9 in pediatric patients. The results were published in a special issue of the US Journal of the Endocrine Society in May this year. It gained attention for reconfirming the potential of GX-H9 as a long-acting recombinant formulation that can be administered weekly or even biweekly.

GX-H9 is a long-acting recombinant human growth hormone fused to hybrid Fc. Handok and Genexine are developing GX-H9 for both children and adults with the goal of a weekly or biweekly dosing regimen. The Phase II study of pediatric patients was conducted in 27 hospitals in ten countries, including European countries and South Korea, and their growth rates were analyzed using data accumulated over two years. The companies compared results between a group of patients to whom GX-H9 had been administered for two years and a group of patients to whom Genotropin®, a weekly formulation, had been administered for one year and then GX-H9 for one year.

The annual growth rates for groups to whom GX-H9 had been administered for two years with weekly doses of 0.8 mg/kg and 1.2 mg/kg were 10.50 cm/year and 11.76 cm/year respectively after one year and 9.14 cm./year and 9.88 cm/year respectively after two years. The annual growth rates for groups to whom a biweekly dose of 2.4 mg/kg had been administered were 11.03 cm/year and 9.72 cm/year at one year and two years, respectively.

For the group that had been dosed Genotropin® and then GX-H9, both for one-year durations, with weekly doses of 0.8mg/kg and 1.2mg/kg, annual growth rates were 8.73 cm/year and 7.60 cm/year respectively. Another group with a biweekly dose of 2.4 mg/kg recorded an annual growth rate of 9.13 cm/year.

In general, growth rates decline as the administration period of the growth hormone is prolonged. However, in this study, a meaningful slowing of the growth rate was not observed in the group to whom GX-H9 had been administered for two years. In addition, the growth rate was maintained without slowing in the group that had been injected with a daily dose of Genotropin® and then a once-weekly or biweekly dose of GX-H9.

The initial study announcement was planned for ENDO 2020 that was to be held in the United States in March 2020, but after this was postponed due to COVID-19, the announcement was published in a special issue of the journal in May. GX-H9 is a cutting-edge growth hormone with weekly and biweekly dosing regimens, in contrast with previous growth hormones that had to be administered daily. GX-H9 received government grant funding as a R&D project by the Korea Drug Development Fund (KDDF) for its advanced technology and was designated by the FDA as an orphan drug for the treatment of growth hormone deficiency in the fourth quarter of 2016. Currently, Handok and Genexine are preparing to apply for a Phase III clinical trial of the long-acting recombinant human growth hormone in the United States. Their Chinese partner I-Mab is also preparing to apply to the National Medical Products Administration (NMPA) for a Phase III clinical trial in China.