Amid a substantial expansion of therapies in several drug classes for the treatment of osteoporosis, there has been a notable increase in the prescription of denosumab for patients with a cancer-related indication.
In an analysis of claims data from January 2009 to March 2020, the bisphosphonate alendronate represented more than 50% of all prescriptions for bone-directed therapies, but growth in the use of the monoclonal antibody denosumab overall and in cancer-related indications particularly was steady throughout the study period.
“In the malignancy cohort, alendronate and zoledronic acid were each used in approximately 30% of individuals at the onset of the study, but use of both then declined,” Sara Cromer, MD, reported at the annual meeting of the Endocrine Society.
For malignancy-based prescriptions, denosumab surpassed either bisphosphonate by 2013 and then continued to rise.
Denosumab use “reached approximately 50% of all bone-directed medication use in the malignancy cohort” by the end of the study period, said Cromer, a clinical research fellow in endocrinology at Massachusetts General Hospital, Boston.
The claims data for this analysis was drawn from the Clinformatics Data Mart. The analysis was restricted to individuals aged older than 50 years who received a prescription for a bone-directed therapy. The 15.48 million prescriptions evaluated were drawn from 1.46 million unique individuals. The mean age was 69 years, and 89% of those prescribed a drug were women.
Table of Contents
Oncologic Indications One of Two Tracked Cohorts
In the context of a large expansion of treatment options in several drug classes for osteoporosis, the objective of this claims analysis was to document trends in treatment choice, according to Cromer. She and her coinvestigators looked at prescriptions overall as well as in two cohorts defined by ICD codes. One included patients prescribed a prescription by an oncologist. The other included everyone else.
When all prescriptions for bone-directed therapy were evaluated over the study period, alendronate was the most commonly prescribed therapy, and its use increased over time. Prescriptions of zoledronic acid also rose, doubling over the study period, but use was very low in the beginning and it never climbed above 5%.
The proportion of prescriptions written for bisphosphonates other than alendronate and zoledronic acid “declined steadily” over the study period, Cromer reported.
Denosumab, a monoclonal antibody that targets a step in the process important to maturation of osteoclasts, was approved in 2010. It accounted for 10% of all prescriptions for osteoporosis by 2015 and 15% by 2018. It was still rising through the end of the study period.
In contrast, prescriptions of raloxifene, a selective estrogen receptor modulator, began to decline after 2013. In general, the rates of prescriptions for other agents, including some of the more recently approved drugs, such as teriparatide, abaloparatide, and romosozumab, changed very little over the study period. None of these therapies ever represented more than 2% of prescriptions.
When looking at the cohort of patients who received a bone-directed reason for a noncancer indication, the trends “paralleled those in the all-user analysis,” Cromer reported.
Denosumab Use Greater in Privately Insured
In the malignancy cohort, the decline in the use of bisphosphonates and the rise in the use of denosumab were most pronounced in patients who were privately insured. The increased use of denosumab over the study period “outpaced gains in use of other agents despite guidelines,” said Cromer, referring to the those issued by the Endocrine Society in 2019 .
In those guidelines, written for management of postmenopausal women at high risk of fractures, bisphosphonates are recommended for initial treatment while denosumab is recommended as an alternative. However, those guidelines do not provide specific recommendations for therapies directed at osteoporosis associated with cancer.
Guidelines for this population exist, including one published by the American Society of Clinical Oncology in 2019.
In the ASCO guidelines, oral bisphosphonates, intravenous bisphosphonates, and subcutaneous denosumab were all identified as “efficacious options,” according to Charles L. Shapiro, MD, director of breast cancer translational research, Mount Sinai Health System, New York.
Specifically, “all three of them work to reduce fractures and improve bone density in women with breast cancer in whom you are trying to prevent or treat osteoporosis,” Shapiro said in an interview.
There might be relative advantages for one therapy over another in specific subgroups defined by type of cancer or stage of cancer, but trials are not definitive for such outcomes as overall survival. Citing one comparative study associating denosumab with an 18% delay to first skeletal event in women with metastatic breast cancer, Shapiro observed, “I personally don’t consider an 18% delay [for this outcome] to be that clinically meaningful.”
Although major guidelines from ASCO have not so far favored denosumab over any bisphosphonate in routine care, Shapiro did not rule out the possibility that future studies will show differences.
Comer and Shapiro reported no relevant conflicts of interest.