BACKGROUND: Teriparatide, approved for treatment of osteoporosis in adults, caused a dose-dependent increase in the incidence of osteosarcoma (OS) in rats during preclinical testing. This study is 1 of 5 OS surveillance studies initiated since initial drug approval in 2002 to evaluate a potential increased risk of OS with teriparatide treatment.
OBJECTIVES: To estimate the incidence rate ratio (IRR) of OS among patients aged 65 years or older treated with teriparatide versus a cohort of matched comparators. The secondary objective was to describe characteristics and similarities of each cohort.
METHODS: All state cancer registries in the United States (US) were invited to participate in this population-based comparative cohort study. Exposure details for each teriparatide user and up to 4 comparators matched on age, sex, 3-digit zip code, date of prescription fill and number of unique therapeutic classes of medications dispensed were identified via Medicare Part D prescription claims. Demographic and clinical characteristics were assessed on a subset using Medicare Parts A, B, and D. Outcomes were identified via linkage with participating state cancer registries through Medicare’s trusted third party. Patients were followed to date of OS diagnosis, death, or end of study.
RESULTS: Among patients, 153,316 in the teriparatide cohort and 613,247 in the comparator cohort were linked to 811 OS cases from 26 participating state cancer registries (covering 68% of US cases aged 65+ diagnosed 2007-2014). Cohorts were predominantly female (91%); 59% were aged 75+ on the index date. Corticosteroid use was higher in the teriparatide versus comparator cohort in the baseline (39% vs. 31%) and follow-up periods (45% vs. 36%). History of fracture was higher in the teriparatide cohort compared to the comparator cohort (23% vs. 8%). The cohorts were well balanced on known OS risk factors and the Charlson comorbidity index. Mean duration of treatment with teriparatide was 10 months. No cases of OS were observed in the teriparatide cohort and the rate in the comparator cohort was consistent with the background rate among adults aged 65+. (To protect patient privacy, non-zero cell counts < 11 cannot be disclosed for Medicare). The IRR was 0.0 (95% CI, 0.0 to 3.2).
CONCLUSIONS: The incidence of OS among teriparatide-treated patients aged 65 years or older in the US ranges from 0 to 3.2 times the incidence of OS in US patients aged 65 years or older treated with other medications. Given the low incidence of OS, this range of effect is inconsistent with a large absolute increase in risk for OS.
