Assessing the incidence of osteosarcoma among teriparatide-treated patients using linkage of commercial pharmacy and state cancer registry data, contributing to the removal of boxed warning and other labeling changes

BACKGROUND

Teriparatide, a recombinant human parathyroid hormone analogue, is associated with increased bone mineral density and a decreased risk of fractures. A dose-dependent increase in the incidence of osteosarcoma was observed in toxicology studies conducted in rats. The primary objective of this study was to estimate the incidence of osteosarcoma over a 10-year period among teriparatide-treated patients versus patients unexposed to teriparatide with osteoporosis and patients in the general population using national pharmacy dispensing data linked with data from participating state cancer registries (SCRs) in the US.

METHODS

Patients aged 18 years or older with a dispensed teriparatide prescription formed two different cohorts: Teriparatide-Osteoporosis (Teriparatide-OP) was formed by matching teriparatide patients to unexposed patients with osteoporosis and Teriparatide-General Population (Teriparatide-GP) was formed by matching teriparatide patients to general population patients with a dispensed prescription for a medication other than teriparatide. Matching was performed using select demographics and other variables. Study cohorts were linked to SCR data to ascertain osteosarcoma status. To account for missing outcome data from non-participating SCRs, two analytic approaches were used: the first adjusted the person-time at-risk using a coverage fraction and the second restricted the analyses to patients from states with participating SCRs.

RESULTS

There were 18 osteosarcoma cases across four study cohorts: the same three cases in the Teriparatide-OP and Teriparatide-GP cohorts, six cases in the Osteoporosis cohort, and nine cases in the General Population cohort. For the analysis using the coverage fraction the incidence rate ratio (IRR) comparing the Teriparatide-OP and Teriparatide-GP cohorts to the Osteoporosis and General Population cohorts was 1.0 (95% CI: 0.2, 4.5) and 1.3 (95% CI: 0.2, 5.1), respectively. When restricting the analysis to patients from states with participating SCRs, the IRR was 0.6 (95% CI: 0.1, 3.6) and 0.8 (95% CI 0.1, 4.0), respectively.

CONCLUSION

The estimates of association between teriparatide and osteosarcoma were imprecise due to the small number of observed osteosarcoma cases. However, the incidence of osteosarcoma observed in each study cohort was within the expected range given background rates for the US general population. The evidence generated by this study, in conjunction with other real-world studies evaluating the risk of osteosarcoma, was used to support changes to the US teriparatide label (including removal of the black box warning regarding potential risk of osteosarcoma) and expand treatment options for patients with osteoporosis.

Long-term cancer surveillance: results from the Forteo Patient Registry Surveillance Study

The Forteo Patient Registry estimated the incidence of osteosarcoma in US patients treated with teriparatide and enrolled in the study between 2009 and 2019. No incident cases of osteosarcoma were identified among patients registered, and the crude incidence rate was 0 (95% confidence interval [CI], 0-10.2) cases per million person-years.

PURPOSE

The prospective, voluntary Forteo Patient Registry was established to estimate the incidence of osteosarcoma in patients who have received treatment with teriparatide (Forteo).

METHODS

Information on US adults prescribed teriparatide and enrolled in the Forteo Patient Registry 2009-2019 was linked with data from participating state cancer registries annually (2010-2019) to identify incident osteosarcoma cases using a standardized linkage algorithm. Teriparatide exposure was ascertained from self-reported data that included teriparatide initiation and demographics necessary to complete linkage. Osteosarcoma cases diagnosed on or after January 1, 2009, were identified by participating state cancer registries. The crude incidence rate (IR) and standardized incidence ratio (SIR) of observed cases to the expected number of cases adjusted to the background rate (3 per million person-years) and corresponding 95% CIs for the occurrence of osteosarcoma were calculated whereby the cumulative amount of person-time observed was adjusted for mortality.

RESULTS

Data for 75,247 enrolled patients (representing 361,763 cumulative person-years) were linked to each of 42 participating state cancer registries (covering 93% of the US population), which included information on 6180 cases of osteosarcoma. No matches with incident cases of osteosarcoma following registry enrollment were found. The crude IR was 0 (95% CI, 0-10.2) cases per million person-years and the SIR was 0 (95% CI, 0-3.0).

CONCLUSIONS

The ability to draw conclusions about the incidence of osteosarcoma among patients participating in the registry was limited due to the smaller than expected amount of patient follow-up time and the fact that no cases were identified.

Teriparatide Did Not Increase Adult Osteosarcoma Incidence in a 15-Year US Postmarketing Surveillance Study

The Osteosarcoma Surveillance Study was initiated in the United States in 2003 to monitor for a potential association between the osteoporosis treatment teriparatide and osteosarcoma. Osteosarcoma occurs at a background incidence rate of approximately 2.5 cases per million per year in US adults aged 40 years or older. For this study, incident cases of osteosarcoma diagnosed between January 1, 2003, and December 31, 2016, were identified through participating cancer registries in the United States. Information on prior exposure to medications and possible risk factors was obtained by self-report (or proxy report) in telephone interviews. Exposure information was verified through medical record abstraction for a sample of patients. A standardized incidence ratio was estimated to compare the observed and expected numbers of osteosarcoma patients with a prior history of teriparatide treatment. Interviews were completed for 24% (1173) of patients diagnosed with osteosarcoma between 2003 and 2016; three reports of teriparatide use before diagnosis were identified. Based on the background incidence rate, the expected number of osteosarcoma cases among patients treated with teriparatide was 4.17. Given the three observed cases, the standardized incidence ratio was 0.72 (90% confidence interval [CI], 0.20 to 1.86). Demographic characteristics were similar for interviewed and noninterviewed patients. Agreement was >90% between self-reported and chart-recorded exposure to osteoporosis medications. Mean age of interviewed patients was 61 years; 53% of patients were male, 84% were white, and 5% were Hispanic. The prevalence of suspected risk factors for development of osteosarcoma among the osteosarcoma cohort was 19% for history of radiation and 4% for history of Paget's disease of bone. These findings showed that the incidence of osteosarcoma associated with teriparatide use during the 15-year surveillance period was no different than would be expected based on the background incidence rate of osteosarcoma. © 2020 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Assessing the incidence of osteosarcoma among teriparatide users based on Medicare Part D and US State Cancer Registry Data

Purpose

During preclinical testing, teriparatide caused a dose‐dependent increase in the incidence of osteosarcoma in rats. This study compared the incidence rate of osteosarcoma among patients aged ≥65 years treated with teriparatide vs a matched‐comparator cohort.

Methods

This population‐based comparative‐cohort study matched exposure details for each teriparatide user, identified via Medicare Part D prescription claims, and up to four comparators based on age, sex, zip code, date of claim for filled prescription, and number of unique therapeutic classes dispensed. Outcomes were identified via linkage with participating cancer registries. All US state cancer registries were invited to participate.

Results

Overall, 153 316 patients in the teriparatide cohort and 613 247 in the comparator cohort were linked to 811 osteosarcoma cases from 26 participating state cancer registries (68% of US patients aged ≥65 years diagnosed 2007‐2014). Analysis on a subset of cohorts revealed they were balanced for known osteosarcoma risk factors and Charlson comorbidity index. Mean duration of teriparatide treatment was 10 months. No osteosarcoma cases were observed in the teriparatide cohort; the incidence rate in the comparator cohort was consistent with the background incidence rate among adults aged ≥65 years. The incidence rate ratio was 0.0 (95% confidence interval, 0.0‐3.2).

Conclusions

For US patients aged ≥65 years, incidence of osteosarcoma among those treated with teriparatide ranges from 0 to 3.2 times the incidence of osteosarcoma in those treated with other medications. Given low incidence of osteosarcoma, this range of effect is inconsistent with a large absolute increase in osteosarcoma risk.

The Forteo Patient Registry linkage to multiple state cancer registries: study design and results from the first 8 years

The Forteo Patient Registry (FPR) aims to estimate the incidence of osteosarcoma in US patients treated with teriparatide. Enrollment began in 2009 and will continue through 2019, with linkage planned through 2024. To date, no incident cases of osteosarcoma have been identified among patients registered in the FPR.

INTRODUCTION

The Forteo Patient Registry (FPR) was established in 2009 to estimate the incidence of osteosarcoma in US patients treated with teriparatide. The objective of this paper is to describe study methods, challenges encountered, and progress to date.

METHODS

The FPR is a prospective US registry designed to link data from participants annually with state cancer registries. Patient enrollment is planned for 10 years (2009-2019) and annual linkage with US state cancer registries for 15 years (2010-2024). All US state cancer registries and DC were invited to participate. Patients are recruited using pre-enrollment materials included in teriparatide device packaging, kits, and brochures distributed by health-care providers; a toll-free number; and a study website. A linkage algorithm is used to match data from enrolled participants with cancer registry data.

RESULTS

For the eighth annual linkage in 2017, information necessary for linkage with 63,270 patients in the FPR was submitted to each of the 42 participating registries. These patients contributed approximately 242,782 person-years of follow-up. A total of 5268 adult osteosarcoma cases diagnosed since January 1, 2009, were available for linkage from participating state cancer registries. To date, no incident cases of osteosarcoma have been identified among patients registered in the FPR.

CONCLUSIONS

Based on the estimated 242,782 person-years of observation as of the eighth annual linkage and projecting current enrollment rate to study end in 2024, it is anticipated that the completed study will be able to detect a fourfold increase in the risk of osteosarcoma if one exists.