The Pharmaceutical Journal
Vol 270 No 7231 p45
11 January 2003

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American Society of Hematology (www.hematology.org)

Complete remission seen for multiple myeloma with new enzyme inhibitor

Complete remission of advanced stage multiple myeloma can be achieved in patients treated with the proteasome inhibitor bortezomib (Velcade), phase II data show.

Bortezomib, which is being developed by Millennium Pharmaceuticals, may be an effective way of targeting cancer cells while sparing healthy ones (PJ, 2 November 2002, p637). Researchers assigned 202 patients with refractory or relapsing multiple myeloma to receive bortezomib 1.3mg/m² body area on days one, four, eight and 11 of a 21-day cycle for up to eight cycles. Before this treatment they had an expected survival time of six to nine months and had previously been treated with an average of six therapeutic regimens.

Of the 193 patients evaluated, complete remission was seen in 4 per cent of patients. This was defined as 100 per cent disappearance in myeloma protein (a marker of tumour burden), negative immunofixation testing (an antibody test for trace amounts of myeloma protein), less than 5 per cent plasma cells in the bone marrow, no increase in size of or number of lytic bone lessions and disappearance of plasmacytomas. Myeloma protein disappeared completely in an additional 6 per cent of patients but their immunofixation test was positive. The mean survival time was 16.4 months and, overall, 59 per cent of patients responded to treatment or their disease stabilised.

In another phase II trial, researchers investigated bortezomib in 54 patients with early stage multiple myeloma who had relapsed after previous first-line treatment. Patients were randomised to receive bortezomib 1mg/m² or 1.3mg/m² body area for up to eight cycles. Those not responding to treatment after two or four cycles were additionally treated with dexamethasone.

Overall, 59 per cent of patients treated with bortezomib 1mg/m² (n=27) and 69 per cent of those treated with bortezomib 1.3mg/m² (n=26) responded to treatment or their disease stabilised. Complete remission was achieved in 4 per cent of each treatment group. Adding dexamethasone increased the overall response rate in both groups.

Data were presented at the 44th annual meeting of the American Society of Hematology held in Philadelphia last month.