INVITRO SYNERGISTIC ACTIVITY OF PDN-IFN-ALPHA AND NM+IFN-ALPHA COMBINATIONS ON FRESH BONE-MARROW SAMPLES FROM MULTIPLE-MYELOMA PATIENTS

The differential staining cytotoxicity (DiSC) assay was used to evaluate the in vitro sensitivity of tumour and normal bone-marrow cells from 21 multiple myeloma (MM) patients to antitumour agents methylprednisolone (PDN), nitrogen mustard (NM) and recombinant interferon alpha-2b (IFN-alpha) tested singly and in the combinations PDN + IFN-alpha and NM + IFN-alpha. Both the PDN-IFN-alpha and NM-IFN-alpha associations were more efficacious than any agents used singly in reducing the percentage of myeloma cell survival. However, whereas NM, alone and in combination with IFN-alpha, provoked a severe reduction in normal bone-marrow population, PDN and PDN + IFN-alpha induced an increase percentage survival of normal bone-marrow cells. These findings indicate that, at least in vitro, the PDN-IFN-alpha combination exerts a great antitumour effect which is not associated with a relevant cytotoxic activity on normal myeloid cells.