Longitudinal patterns of bone-targeted agent use among patients with solid tumors and bone metastases in the United...

This study examined real-world long-term use of guideline-recommended bone targeted agents (BTA) among patients with metastatic solid tumors.

Adults with a solid tumor diagnosis followed by a bone metastasis diagnosis in 2012-2014 were identified from electronic medical records in the Oncology Services Comprehensive Electronic Records (OSCER) database. Patients initiated zoledronic acid (ZA) or denosumab on or after the bone metastasis diagnosis and were followed through last clinic visit by 30 June 2015. We describe time to BTA initiation, compliance (≥12 administrations in a year), switching, and non-persistence (switch or ≥90 day gap in therapy), by agent and follow-up period.

The majority of the 14,881 study patients (50% female, 65% age ≥65 years) had breast (33%), prostate (26%), or lung (26%) tumors. Half of all patients initiated on each agent, with denosumab initiations exceeding ZA initiations in 2014. Most (91% denosumab, 93% ZA) initiations occurred within 3 months of bone metastasis diagnosis. At 1, 2, and 3 years post-initiation, denosumab patients were less likely to switch agents (4, 3, and 1% versus 14, 12, and 11%) and more likely to be compliant (50, 37, and 31% versus 41, 26, and 6%). Median time to non-persistence was 25.9 months for denosumab and 17.2 months for ZA, p < 0.0001.

This is the first study reporting long-term treatment patterns for the two primary BTAs used in the USA. The greater compliance and longer persistence observed among denosumab patients may improve treatment effectiveness achieved in the real-world setting.