Extract from the mushroom Agaricus blazei Murill har been shown to have strong immunomodulating properties both in cell cultures, animal models and in humans. Furthermore antitumor properties have been shown in animal models, among them in mice with multiple myeloma. The investigators now want to investigate the effect of Agaricus as supplementary treatment in addition to chemotherapy in patients with multiple myeloma.

Patients who are scheduled to undergo high dose chemotherapy for multiple myeloma will receive in addition in a double blinded manner 60 ml of agaricus extract or placebo once daily from the start of stem cell mobilizing therapy until one week after the end of aplasia after high dose melphalan.

Primary endpoints will be cytokine levels of degree of activation of tumor supressor genes before and after start of the investigational product.

Secondary endpoints will be treatment response and quality of life.

Inclusion Criteria:

• Patients scheduled to undergo high dose chemotherapy with autologous stem cell support for multiple myeloma

Exclusion Criteria:

• None