Comparison of Forteo and PF708 teriparatide on improvements in bone mineral density

Background: PF708 teriparatide, manufactured by Alvogen, was approved through the 505(B)(2) application after the expiration of Forteo market exclusivity in October 2019. The 505(B)(2) application allows safety and efficacy information to come from studies not conducted by the applicant if it is demonstrated that the proposed product shares characteristics (active ingredient, dose, route of administration, strength) with the reference product and comparable pharmacokinetic data are established. Thus, more information is needed to provide real-world safety and efficacy outcomes data for PF708 teriparatide. Objective: This study aimed to determine whether there is a clinically meaningful difference in change from baseline in bone mineral density (BMD) at the lumbar spine in osteoporotic patients treated with either Forteo or PF708 teriparatide for 18-24 months. Methods: This retrospective chart review included osteoporotic patients aged 18 years and older who received PF708 teriparatide or Forteo prescriptions from the practice location and initiated therapy between October 1, 2019, and October 31, 2022. Patients without dual-energy X-ray absorptiometry results at the conclusion of therapy or who did not complete at least 18 months of therapy were excluded. The primary end point was the percent change from baseline in BMD at the lumbar spine. Data were analyzed using linear regression adjusted for age, sex, and baseline BMD with a significance level of 0.05. Results: A total of 108 patients were included: 27 (median age 67 years, 88.9% female) in the PF708 teriparatide group and 81 (median age 68 years, 85.2% female) in the Forteo group. Linear regression adjusted for age, sex, and baseline BMD showed no statistically significant difference in the change from baseline BMD at the lumbar spine (+9.6% vs. +7.7%, P = 0.93). Adverse effects were reported in 7.4% of patients in the teriparatide group and 9.9% of patients in the Forteo group. The most common reported adverse effects were constipation, nausea, and fatigue. No statistically significant differences were detected in the percent change from baseline BMD at the femoral neck and hip. Conclusion: In this small retrospective study, there was no statistically significant difference detected in the effect on BMD at the lumbar spine between PF708 teriparatide and Forteo when used for the recommended duration of therapy. The rate of adverse events occurred at similar rates in both groups. These results contribute real-world outcomes data on the use of PF708 teriparatide and Forteo formulations and are intended to be exploratory and hypothesis generating.