Osteoporosis therapies — some answers but still some questions

ASBMR 30th Annual Meeting

The annual meeting of the American Society for Bone and Mineral Research, held over the weekend in Montreal, offered news about osteoporosis therapies in phase-2 and phase-3 clinical trials, and the pipeline for the near future looks great.

For the here and now there were mixed data about the potential side effects of bisphosphonates. Osteonecrosis of the jaw remains a rare complication when bisphosphonates are used in appropriate doses for osteoporosis. The “frozen bone” upper femur fractures that have been headlined of late are not as closely linked to bisphosphonates as the media would have us believe. True, the fractures through the upper femoral shaft have occurred in bisphosphonate-treated patients but a fairly large retrospective study concluded that the occurrence rate is no greater than in patients not treated with bisphosphonates.

I kept hearing a buzz that there are lingering concerns about bisphosphonates and cardiovascular health but I heard nothing that makes this much more than a rumor for now.

One big disappointment is that we are not much closer to having a good protocol for transitioning patients from bisphosphonates to teriparatide for treatment of osteoporosis. There is no question that teriparatide is as effective long term when given to patients who have previously been on bisphosphonates as it is in bisphosphonate-naive patients. What remains unresolved is whether one should switch immediately to teriparatide in a bisphosphonate “failure” patient or delay the switch for a few months after stopping bisphosphonate therapy. Clinically this is a tough call because many of these patients are referred soon after they have sustained a fracture while taking bisphosphonates. The prudent thing to do would be to begin teriparatide immediately.

Things are less clear for patients who are considered bisphosphonate-treatment failures because bone mineral density has either not continued to increase or has decreased. The information I heard suggested that the effect of teriparatide on BMD may be delayed for a few months if begun immediately after stopping bisphosphonates. But this was data from clinical research studies in which BMD was monitored at six monthly intervals. After 12 months of teriparatide there was a clear increase in BMD that paralleled the increase seen in patients who had never received bisphosphonates but there did not seem to be any catch-up effect.

My recommendation, not based on strong evidence, is that it is better to have a six-month period off bisphosphonates before switching to teriparatide unless the patient has sustained an osteoporosis-related fragility fracture. I would not recommend continuing bisphosphonates as teriparatide is initiated.