COMPARISON OF PERIPHERAL-BLOOD PROGENITOR-CELL MOBILIZATION IN PATIENTS WITH MULTIPLE-MYELOMA - HIGH-DOSE CYCLOPHOSPHAMIDE PLUS GM-CSF VS G-CSF ALONE

The best method for peripheral blood progenitor cell (PBPC) mobilizati on in patients with multiple myeloma (MM) remains controversial. We re port the results of two different methods of PBPC collection for autol ogous transplantation in 40 patients with stage II or III MM. In group I (n = 18), HD-CY, 4 g/m(2) i.v., was administered followed by GM-CSF , 8 mu g/kg/day s.c., until the end of collection, starting the leukap hereses after hematological recovery (>1 x 10(9)/l WBC). In group II ( n = 22), G-CSF, 10 mu g/kg/day s.c., was used alone until the last day of collection, starting consecutive aphereses on the 5th day. A minim um of two aphereses were performed to collect at least 2 x 10(6)/kg CD 34(+) cells. Both patient groups were comparable for age, sex and clin ical prognostic features as well as previous therapies. In group I, th e median yields per pheresis were: MNC 1.47 (1.38-2.32) x 10(8)/kg, CF U-GM 0.82 (0.18-13.2) x 10(4)/kg and CD34(+) cells 1.98 (0.96-6.96) x 10(6)/kg. In group II these results were: MNC 2.44 (2.06-3.6 x 10(8)/k g) (P = 0.03), CFU-GM 0.75 (0.16-7.8) x 10(4)/kg and CD34f 1.05 (0.32- 3.4) x 10(6)/kg (P = 0.02). The median number of aphereses performed i n each group was 5 (4-12) with a median of 5.24 +/- 2.51 in group I an d 3 (2-6) with a median of 3.1 (+/-0.91) in group II (P = NS). Hospita lization for PBPC mobilization was required in all patients in group I and the treatment-related toxicity was greater in this group: 12 pati ents (66%) developed fever requiring antibiotics during the neutropeni c period after HD-CY and six (33%) patients required transfusion suppo rt. After receiving busulfan 12 mg/kg p.o. and melphalan 140 mg/m(2) i .v., as the conditioning regimen, the median periods to reach granuloc ytes (>0.5 x 10(9)/l) and platelet (>20 x 10(9)/l) engraftment were 12 and 11 days respectively (ranges 8-20 and 10-16) in group I (HD-CY pl us GM-CSF group), and 11 and 13 days respectively (ranges 7-42 and 10- 38) in group LI (G-CSF group) (P = NS). In conclusion, these data sugg est that although HD-CY plus GM-CSF is superior to G-CSF alone based o n mean CD34(+) cell yield per pheresis, adequate CD34(+) cell collecti ons can be achieved with G-CSF alone in most MM patients with less tox icity and with simplification of the procedure.