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Tanespimycin (17-allylamino-17-demethoxygeldanamycin, 17-AAG) disrupts heat shock protein 90 (HSP90), a key molecular chaperone for signal transduction proteins critical to myeloma growth, survival and drug resistance. In previous studies, tanespimycin monotherapy was well tolerated and active in heavily pretreated patients with relapsed/refractory multiple myeloma (MM). Preclinical data have shown antitumour synergy between tanespimycin and bortezomib, with more pronounced intracellular accumulation of ubiquitinated proteins than either drug alone, an effect attributed to the synergistic suppression of chymotryptic activity in the 20S proteasome. HSP70 induction has been observed in all Phase 1 tanespimycin studies in which it has been measured, with several separate reports of HSP70 overexpression protecting against peripheral nerve injury. In this Phase 2, open-label multicentre study, we compared 1.3 mg/m2 bortezomib + three doses of tanespimycin: 50, 175 and 340 mg/m2 in heavily pretreated patients with relapsed and refractory MM and measured HSP70 expression and proteasome activity levels in plasma of treated patients. The study was closed prematurely for resource-based reasons, precluding dose comparison. Nonetheless, antitumour activity was observed, with promising response rates and promising severity of peripheral neuropathy.

A 39-year-old male presented with pedal edema, pleural effusion, splenomegaly, and generalized lymphadenopathy. Serum protein electrophoresis demonstrated the presence of a monoclonal protein. Histological examination of the spleen following splenectomy showed multifocal vascular proliferation and angiovascular lesions consistent with multicentric Castleman disease. He was treated with steroids and rituximab, but without improvement. The patient was found to have portal venous thrombosis and lower extremity arterial thrombosis. He then received combination chemotherapy with cyclophosphamide and mitoxantrone but developed a severe inflammatory polyneuropathy that left him disabled and wheelchair-bound. A diagnosis of multicentric Castleman disease with POEMS syndrome was made, and he then received high-dose chemotherapy with melphalan followed by autologous peripheral blood stem-cell transplantation. Following transplantation, his nerve conduction studies improved and his serum protein electrophoresis normalized. He is currently ambulatory and does not need wheelchair assistance. Hematopoietic stem-cell transplantation may be a treatment option for patients with multicentric Castleman disease and POEMS syndrome.

Peripheral blood progenitor cells (PBPCs) are becoming the stem cell source of choice for rescuing patients from marrow aplasia after high-dose chemotherapy. Their advantages over bone marrow include avoidance of general anesthesia and more rapid hematologic recovery after transplantation. More rapid engraftment can reduce the risks associated with transplantation and shorten the hospital stay or, under certain circumstances, eliminate it. The cost reductions associated with a shorter stay have made PBPC transplantation cost-competitive with more conventional therapy. The move to outpatient transplantation requires increased patient and family involvement with posttransplantation care, as well as increased patient education and a multidisciplinary care team for the safe transition of patients between care sites. Improvements in outpatient transplantation may incorporate a cooperative care model with the intent of reducing readmission rates and extending this modality to most patients who undergo autologous transplantation.