Pfizer’s Ngenla Approve for Pediatric Growth Hormone Deficiency in South Korea

On February 2, 2023, Pfizer Korea's "Ngenla Prefilled Pen Injection" received approval in South Korea for the treatment of pediatric growth hormone deficiency. As of September 1, this treatment is now covered by insurance, raising questions about its potential impact on the existing $180.5 million growth hormone market, primarily dominated by daily administration products.

Ngenla, containing "Somatrogon" as its active ingredient, is now covered by insurance for treating pediatric growth deficiency caused by pituitary growth hormone secretion disorders in children aged 3 and older. It is available in two approved doses: 24mg and 60mg.

Currently, the market mainly offers growth hormone products based on "Somatropin." Eight product groups are available, including LG Chem's "Eutropin," Dong-A ST's "Growtropin-2," Merck Korea's "Saizen," Novo Nordisk's "Norditropin NordiFlex," Pfizer Korea's "Genotropin," Scigen Korea's "Scitropin," Ferring Korea's "Zomacton," and LG Chem's "Declage."

According to IQVIA, a market research organization, last year's total sales in the domestic Somatropin product market amounted to approximately $179.5 million. The top-selling product was Eutropin, with $63.8 million in sales, followed closely by Growtropin-2 with $35.6 million, Saizen with $24.8 million, Norditropin NordiFlex with $23.4 million, and the Genotropin product group (Genotropin Pfizer, Genotropin GoQuick) with $23.1 million.

Currently, these products share the same insurance coverage criteria as Ngenla for pediatric growth hormone deficiency. To be eligible for partial patient cost-sharing, patients must meet specific criteria: their height must fall below the 3rd percentile for their chronological age, confirmed through two or more growth hormone stimulation tests. Additionally, they must be pediatric patients aged 3 or older with growth hormone secretion disorders where bone age is less than chronological age. Treatment can begin at the age of 3 years in chronological age and continue until bone growth plates close. However, insurance coverage only applies up to a bone age of 14-15 years for females and 15-16 years for males. Patients whose height exceeds 153 cm for females and 165 cm for males will be responsible for covering the full cost themselves.

With Ngenla and existing growth hormone products now on par for pediatric growth hormone deficiency patients, clinicians are evaluating which product may improve patient compliance. During a Pfizer Korea press conference on September 14th, Dr. Hyun-Wook Chae, a pediatric endocrinologist at Gangnam Severance Hospital, emphasized that the crucial factors in pediatric growth hormone deficiency treatment are the speed and duration of growth hormone therapy, underlining the importance of timely and continuous treatment for these patients.

Dr. Chae stressed the significance of long-term treatment compliance. Traditional Somatropin products required patients to receive injections 6-7 times a week, with missing injections three or more times a week significantly slowing down growth rates. To enhance compliance, he suggested that the development of a similar injection with extended dosing intervals and reduced injections would be the optimal approach.

In a global Phase 3 clinical trial involving 228 pediatric patients aged 3 to under 7 with growth hormone deficiency, the Ngenla group demonstrated an annual growth rate of height of 10.1 cm at the 12-month mark, compared to the Genotropin group's growth rate of 9.78 cm per year from daily growth hormone injections. This resulted in a difference of 0.33 cm (95% CI: -0.24, 0.89) in annual height growth between the two formulations. Pfizer used these results to secure Ngenla's approval, demonstrating its non-inferiority compared to traditional Somatropin products.

However, Ngenla exhibited a higher incidence of adverse reactions related to injection pain compared to traditional Somatropin products. The Ngenla group reported 868 adverse reactions, while the Genotropin group reported 570 adverse reactions. Most of the adverse reactions associated with Ngenla were related to "injection pain" due to the larger once-a-week dosage, which researchers generally found tolerable.

Industry experts continue to express interest in once-weekly growth hormone formulations, given the pediatric target audience and the desire to reduce the psychological and physical burden of injections. There is significant anticipation regarding whether the newly reimbursed Ngenla will impact the growth hormone product market in the coming months.