Forsteo ® (teriparatide)

This information is intended for UK registered healthcare professionals only as a scientific exchange in response to your search for information. Please refer to the link for full prescribing information: Forsteo Summary of Product Characteristics (SmPC)

Forsteo® (teriparatide): Osteosarcoma Data

Studies in rats indicate an increased incidence of osteosarcoma with long-term administration of teriparatide. Until further clinical data become available, the recommended treatment time of 24 months should not be exceeded.

Preclinical Safety Data

Rats treated with near-life time daily injections had dose-dependent exaggerated bone formation and increased incidence of osteosarcoma most probably due to an epigenetic mechanism. Teriparatide did not increase the incidence of any other type of neoplasia in rats. Due to the differences in bone physiology in rats and humans, the clinical relevance of these findings is probably minor. No bone tumours were observed in ovariectomised monkeys treated for 18 months or during a 3-year follow-up period after treatment cessation. In addition, no osteosarcomas have been observed in clinical trials or during the post treatment follow-up study.1

Clinical Experience

An analysis conducted in 2012 found that in the more than 16,000 patients who received teriparatide in controlled clinical trials and observational studies, there were no cases of osteosarcoma reported.2

Postmarketing Experience

Cases of bone tumor and osteosarcoma have been reported rarely in the postmarketing period. The causality to teriparatide use is unclear.3

The cumulative number of spontaneous reports with a pathology-confirmed diagnosis of osteosarcoma in the teriparatide-treated population does not exceed what would be predicted based on background incidence alone.3

Osteosarcoma continues to be the focus of long-term postmarketing surveillance efforts. Any communication to Lilly that includes a potential report of osteosarcoma is further investigated and reported expeditiously to the FDA and to other regulatory authorities.

Treatment considerations

In rats, teriparatide caused a dose-dependent increase in the incidence of osteosarcoma, a malignant bone tumor. Because of the uncertain relevance of the rat osteosarcoma finding to humans, prescribe teriparatide only for patients for whom potential benefits outweigh potential risk.3

Teriparatide should not be prescribed for patients at increased baseline risk for osteosarcoma. Increased risks include:3

  • Paget’s disease of bone

  • Unexplained elevations of alkaline phosphatase (elevations in alkaline phosphatase may signal undiagnosed Paget’s disease of bone)*

  • Pediatric and young adult patients with open epiphyses

  • Prior external beam or implant radiation therapy involving the skeleton

Teriparatide treatment has been shown to elevate BSAP as part of its mechanism of action; this elevation is expected.3


1. Forsteo [summary of product characteristics]. Eli Lilly Nederland B.V., The Netherlands.

2. Andrews EB, Gilsenan AW, Midkiff K, et al. The US postmarketing surveillance study of adult osteosarcoma and teriparatide: study design and findings from the first 7 years. J Bone Miner Res. 2012;27(12):2429-2437.

3. Data on file, Eli Lilly and Company and/or one of its subsidiaries.


ALP = bone alkaline phosphatase

BSAP = bone-specific alkaline phosphatase

FDA = Food and Drug Administration

Date of Last Review: February 17, 2020

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