Interruption of Bisphosphonates (BP) Therapy in Multiple Myeloma (MM) Patients and Osteonecrosis of the Jaw (ONJ).

ONJ is a serious complication in MM patients; incidence is time-dependent with highest risk seen after long-term use of BP in older MM patients, often after dental surgical procedure (Badros, et al JCO 2006). Therapy has focused on debridement of necrotic bone, infection management, pain control and discontinuation of BP. The association between BP and ONJ remains provisional; theoretically and anecdotally, however there is evidence that BP withdrawal may allow for recovery of normal osteoclast function and reversal of antiangiogenic effects of the drug on the periosteum allowing for bone healing. We have observed an increased risk of skeletal complications in MM patients after long interruptions of BP therapy (6–12+months), even though patients had been on BP therapy for a median of 3 yrs (range: 2–10+yrs). Table below summarizes the complications that occurred off BP therapy in MM patients with ONJ (n=28) and without ONJ who stopped BP ahead of dental procedures (n=20). Skeletal complications included avascular necrosis of the hip (AVN), fractures, new lytic lesions on skeletal surveys and bone pain; all occurred in relapsed patients with active MM. These events highlighted the importance of BP cornerstone for treatment of skeletal complications of MM; of the 28 ONJ patients, 8 died from progressive MM and 3 patients had non-healing oral lesions and did not resume BP. Twelve of 17 ONJ patients were restarted on BP after complete healing of the oral lesions; all of whom had relapsed MM and bone disease. They received pamidronate every 3 months. So far 3 of 12 patients (25%) had recurrent ONJ and none had skeletal complications. Of the 20 patients who stopped BP before dental procedures, 3 (15%) went on to develop ONJ. Fifteen had restarted BP 2–3 months after the procedure site was well-healed; one patient developed ONJ at the healed extraction site 6 months after restarting BP therapy. This patient was in remission on maintenance thalidomide but with extensive myeloma bone disease. In conclusion, interruption of BP in MM patients with ONJ as well as before and after dental procedures had inconsistent results with regards to both healing and prevention of ONJ. On the other hand, the damage of holding BP therapy is evident with increased frequency of skeletal complications. Until further studies define the optimal frequency and duration of BP therapy, we propose continuous administration of BP therapy probably less frequently after 2 years of monthly infusions with careful assessment of the risk status of each individual patient.