Response to bortezomib is associated to osteoblastic activation in patients with multiple myeloma

Summary The prompt response to bortezomib observed in a 63‐year‐old woman with multiple myeloma was associated with a significant increase in alkaline phosphatase (ALP). After similar elevations were noted in patients responding to bortezomib, thalidomide, dexamethasone combination, ALP levels were analysed in two large bortezomib trials. A statistically significant elevation of ALP from baseline was observed in responding patients (complete and partial responders) within three cycles of therapy. The rise in ALP after bortezomib in three patients was explained by a parallel increase in bone‐specific ALP and parathyroid hormone, suggesting that response to bortezomib in myeloma is closely associated with osteoblastic activation.