Phase I trial of fludarabine, bortezomib and rituximab for relapsed and refractory indolent and mantle cell non-Hodgkin lymphoma.

Based on the hypothesis that bortezomib may potentiate fludarabine activity by inhibiting DNA repair, we designed a phase I trial using this combination with rituximab in patients with relapsed and refractory indolent and mantle cell non-Hodgkin lymphoma. Twenty-four patients were enrolled. Non-Hodgkin lymphoma subtypes included 12 patients with follicular lymphoma, four with marginal zone lymphoma, three with lymphoplasmacytic lymphoma, three with mantle cell lymphoma and two with small lymphocytic/chronic lymphocytic leukaemia. Fludarabine and bortezomib were escalated in cohorts of three patients. Rituximab was added to the maximum tolerated dose of fludarabine and bortezomib and added significant dose-limiting myelosuppression. The maximum tolerated dose was fludarabine 25 mg/m(2) on days 1-3, bortezomib 1.3 mg/m(2) on days 1, 4, 8, 11, with rituximab 375 mg/m(2) on day 1 administered every 21 d. Clinical responses were observed in 11 patients, five of whom were refractory to their most recent treatment regimen. Six additional patients had stable disease for a median of 10 months (range 4-30+). Cumulative myelosuppression and neuropathy was observed. The combination of fludarabine, bortezomib, and rituximab appears to be an active regimen with manageable toxicity for relapsed NHL.

Thrombotic microangiopathy in haematopoietic stem cell transplantation: diagnosis and treatment.

Each year in the US, more than 10 000 patients benefit from allogeneic haematopoietic stem cell transplantation (HSCT), a modality that offers an excellent chance of eradicating malignancy but confers a higher risk of treatment-related mortality. An uncommon but devastating consequence of HSCT is transplantation-associated thrombotic microangiopathy (TA-TMA). The incidence of TA-TMA ranges from 0.5% to 76%, with a mortality rate of 60-90% despite treatment. Although there appears to be a consistent treatment approach to idiopathic thrombotic thrombocytopenic purpura (TTP) using plasma exchange, corticosteroids and rituximab, the treatment strategies for TA-TMA are perplexing, in part, because the literature regarding this complex condition does not provide true consensus for incidence, aetiology, diagnostic criteria, classification and optimal therapy. The classic definition of idiopathic TTP includes schistocytes on the peripheral blood smear, thrombocytopenia and increased serum lactate dehydrogenase. Classic idiopathic TTP has been attributed to deficient activity of the metalloproteinase responsible for cleaving ultra-large von Willebrand factor multimers. This protease is a member of the 'a disintegrin and metalloprotease with thrombospondin type 1 motif' family and is subsequently named ADAMTS-13. Severely deficient ADAMTS-13 activity (<5% of normal) is associated with idiopathic TTP in 33-100% of patients. In constrast to the pathophysiology of idiopathic TTP, patients with TA-TMA have >5% ADAMTS-13 serum activity. These data may explain why plasma exchange, a standard treatment modality for idiopathic TTP that restores ADAMTS-13 activity, is not effective in TA-TMA. TA-TMA has a multifactorial aetiology of endothelial damage induced by intensive conditioning therapy, irradiation, immunosuppressants, infection and graft-versus-host disease. Treatment consists of substituting calcineurin inhibitors with an alternative immunosuppressive agent that possesses another mode of action. One candidate may be daclizumab, especially in those with mild to moderate TMA. Rituximab therapy or the addition of defibrotide may also be beneficial. In general, plasma exchange is not recommended.