POLE OF CD34(-DOSE MELPHALAN IN MULTIPLE-MYELOMA PATIENTS GIVEN PERIPHERAL-BLOOD STEM-CELL RESCUE() CELLS IN ENGRAFTMENT AFTER HIGH)

During the period December 1992 to June 1995, 95 patients were treated with high-dose melphalan (HDM) with peripheral blood stem cell rescue (PBSCR), Sixty-five had received previous treatment and 28 had relaps ed. Among patients who had relapsed 21/28 had received HDM previously including one who received HDR I twice during the course of the study, Seventy-five patients were given HDM/PBSCR for the first time. Compar isons have been made between engraftment times for platelets and neutr ophils among patients who received less than or greater than 2 x 10(6) CD34(+) cells at rescue, Analyses have also been done to evaluate the effect of previous HDM on recovery, Mobilization of progenitor cells was done with granulocyte colony-stimulating factor (G-CSF). Patients received only PBSCR. No growth factors were given to the PBSCR recipie nts during the recovery period, The percentage of patients from whom t he number of CD34(+) cells mobilized was >2 x 10(6)/kg was similar in patients who received HDM for the first time (23%) compared with those who had had it previously (19%), The yield of CD34(+) cells correlate d with the number of granulocyte-macrophage colony forming units (CFU- GM). Although the number of CD34(+) cells infused was <2 x 10(6)/kg in 77% of patients, all engrafted for neutrophils to >0.5 x 10(9)/l. Thi s was delayed in patients who had had previous HDM (P < 0.02). Platele t recovery to >25, 50 and 100 x 10(9)/l was delayed in all patients wh o received <2 x 10(6) CD34(+) cells/kg infused (P < 0.02). In patients who had had previous HDM both neutrophil (P < 0.05) and platelet reco very (P < 0.007) were delayed compared with recovery in patients who h ad not had HDM. In patients who had had previous HDM and received <2 x 10(6) CD34(+) cells/kg infused only 3/17 regained platelets to >100x1 0(9)/l compared with 3/4 who had >2 x 10(6) CD34(+) cells/kg infused ( P < 0.05 Fisher's exact test), There was no evidence that low numbers of CD34(+) cells in the PBSCR were associated with early death, The da ta show that previous treatment with HDM had adverse effects on the su bsequent engraftment of platelets among patients given HDM/PBSCR. The data suggest that additional measures are needed to achieve platelet r econstitution in these heavily pre-treated patients.