The opening talk at this 2015 EULAR session on osteoporosis addressed techniques for measuring bone quality. Dr Claus Glüer described new techniques for assessing trabecular and cortical bone strength such as HR peripheral quantitative CT and HRCT spine. Two investigational techniques include point indentation which is a minimally invasive assessment of bone quality, and quantitative ultrasound of cortical bone. While not quite ready yet for prime time, these may someday offer more accurate measures of bone quality and fracture risk, our ultimate treatment goal.
Dr Socrates Papapoulos gave an elegant summary of treatments for OP. Several drugs have fallen out of favour since they do not meet our goal of fracture prevention. In particular, calcitonin has limited efficacy plus increased toxicity. Estrogen has an unfavourable risk-benefit profile with concerns regarding breast cancer and cardiovascular disease. Strontium also has toxicity concerns and should be reserved only for high-risk patients. This leaves bisphosphonates and denosumab, which have data for protection against vertebral and nonvertebral fractures.
What about new targets? The LOFT trial showed that odanacatib, a cathepsin K inhibitor, has efficacy similar to bisphosphonates. This once-weekly oral agent inhibits absorption while preserving bone formation. Another trial investigated the combination of denosumab plus PTH and showed improvement in BMD, but more data are needed on safety and fracture risk reduction. Finally, romosozumab, an antibody against sclerostin, is currently in phase 3 clinical trials. Preliminary evidence suggests it may have anabolic effects on bone mass that are superior to teriparitide.
Whether or not to stop OP therapy after 3 to 5 years in selected patients remains a clinical controversy. This is driven by potential safety concerns of osteonecrosis of the jaw and atypical femoral fractures. Dr Kenneth Saag pointed out that ONJ is very rare in the OP population but AFF may be a concern especially with longer duration of therapy. So far we may just be seeing the tip of the iceberg with these events.
Current guidelines from ASBMR suggest reevaluation of BMD and clinical fracture assessment after 3 to 5 years of therapy. If there has been no fracture plus a stable BMD, consider a drug holiday. Dr Saag likes the term "drug sabbatical" for high-risk patients on steroids who continue to fracture or who continue to lose bone. These patients may be candidates for a holiday from bisphophonate therapy with consideration of switching to another therapy such as denosumab or PTH. Denosumab has the benefit of a short duration of action but the drawback of rare cases of AFF.
Overall this session was a good start to the 2015 EULAR meeting.
Dr. Shelley Dunne is a graduate of Memorial University of Newfoundland School of Medicine. She completed her training in Internal Medicine and a fellowship in Rheumatology at the University of Toronto. She has been in private practice since 1998 and is currently a consulting rheumatologist at the Toronto East General Hospital.View Full Bio