A multicenter trial of myeloablative clofarabine and busulfan conditioning for relapsed or primary induction failure AML not in remission at the time of allogeneic hematopoietic stem cell transplantation.

Allogeneic hematopoietic cell transplantation (HCT) may produce long-term survival in AML after relapse or primary induction failure (PIF). However, outcomes of HCT performed for AML not in remission are historically poor given high relapse rates and transplant-related mortality. Preliminary studies suggest conditioning with clofarabine and myeloablative busulfan (CloBu4) may exert significant anti-leukemic effects without excessive toxicity in refractory hematologic malignancies. A prospective multicenter phase II trial was conducted to determine the efficacy of CloBu4 for patients proceeding directly to HCT with AML not in remission. Seventy-one patients (median age: 56 years) received CloBu4. At day 30 after HCT, 90% achieved morphologic remission. The incidence of non-relapse mortality and relapse at 2 years was 25% and 55%, respectively. The 2-year overall survival (OS) and event-free survival (EFS) were 26% and 20%, respectively. Patients entering HCT in PIF had significantly greater EFS than those in relapse (34% vs 8%; P<0.01). Multivariate analysis comparing CloBu4 with a contemporaneous cohort (Center for International Blood and Marrow Transplantation Research) of AML not in remission receiving other myeloablative conditioning (n=105) demonstrated similar OS (HR: 1.33, 95% confidence interval: 0.92-1.92; P=0.12). HCT with myeloablative CloBu4 is associated with high early response rates and may produce durable remissions in select patients with AML not in remission.

High-dose chemotherapy with reinfusion of purged autologous bone marrow following dose-intense induction as initial therapy for metastatic breast cancer.

We assessed the toxicity and efficacy of high-dose chemotherapy consolidation with reinfusion of purged autologous bone marrow in women with metastatic breast cancer responding to a dose-intense outpatient regimen. Thirty women with hormone-unresponsive metastatic breast cancer, previously untreated with adjuvant doxorubicin or with any chemotherapy for metastatic disease, were treated with cyclophosphamide, methotrexate, doxorubicin, fluorouracil, vincristine, and leucovorin for 16 weeks. Twenty-four patients responded to therapy; 8 showed a complete response, and 16 showed a partial response. These patients proceeded to the next phase of the protocol, ie, marrow harvest and treatment with 6000 mg/m2 cyclophosphamide and 800 mg/m2 thiotepa given over 4 days. Harvested marrow was purged with 100 micrograms/mL 4-hydroperoxycyclophosphamide, and all patients engrafted satisfactorily. The predominant side effects were myelosuppressive and gastrointestinal, and there were no deaths from toxic effects. Three of the 16 patients who showed a partial response after the outpatient phase of treatment achieved a complete response after high-dose therapy. The partial response seen in two more patients converted to a complete response at all sites except bone. The median time to disease progression for all patients in this study was 13 months, and the median survival was 22 months. Four of the original 30 patients remained without disease progression a median of 27 months from entry into the study. This study indicates that this dose-intense regimen can be safely administered, even with the use of purged marrow, with an acceptable toxicity profile. This approach results in a high response rate in women with metastatic breast cancer and could form the basis for a regimen to be tested in the high-risk adjuvant setting.

Phase I study of combination drug purging for autologous bone marrow transplantation.

In a phase I clinical trial of autologous bone marrow transplantation, we determined the feasibility of ex vivo purging with high concentrations of pharmacologics in combination. Light-density cells isolated from the grafts of 26 patients with acute leukemia or lymphoblastic lymphoma were treated with 4-hydroperoxycyclophosphamide (4-HC; 30 to 60 micrograms/mL), vincristine (Vcr; 1.5 to 3.0 micrograms/mL), and methylprednisolone sodium succinate (MP; 5 mg/mL). All patients received marrow-lethal induction therapy followed by infusion of the treated grafts. Three patients died of transplant-related complications before achieving peripheral blood recovery of greater than 0.5 x 10(9) granulocytes per liter. All other patients achieved this parameter of engraftment at a median of 35 days after marrow infusion. The median time to last platelet transfusion was 45 days. These durations of aplasia were similar to those experienced by other patients receiving density-gradient separated grafts treated with 60 micrograms/mL of 4-HC as a single agent. No patient required infusion of untreated reserve marrow because of engraftment failure. The colony-forming unit-granulocyte macrophage (CFU-GM) content of the grafts after purging predicted these parameters of engraftment. Colony-forming unit-leukemia (CFU-L) cultured from the grafts of 12 of the patients treated for acute lymphoblastic leukemia (ALL) were considerably more sensitive to the combination regimen than to 4-HC alone; the sensitivity of CFU-GM from these patients did not differ between the two regimens. The results of this trial indicate the feasibility of treating autologous bone marrow grafts with high concentrations of pharmacologics in combination. The use of combinations may increase the efficacy of ex vivo purging without increasing the toxicity to normal hematopoietic cells.

High-dose cytotoxic therapy and bone marrow transplantation for relapsed Hodgkin's disease.

Patients with Hodgkin's disease who have failed two or more chemotherapy regimens or who have relapsed after an initial chemotherapy-induced remission of less than 12 months are seldom cured with conventional salvage therapies. We studied the effect of high-dose cytoreductive therapy followed by bone marrow transplantation in 50 such patients with relapsed Hodgkin's disease. Twenty-one patients with histocompatibility locus antigen (HLA)-matched donors had allogeneic marrow transplants, one patient received marrow from an identical twin, and 28 patients without a matched donor received autologous grafts purged with 4-hydroperoxycyclophosphamide. Busulfan plus cyclophosphamide was the preparative regimen for the 25 patients who had received extensive prior irradiation, and the other 25 patients received cyclophosphamide plus total body irradiation. The overall actuarial probability of event-free survival at 3 years was 30%, with a median follow-up of 26 months. The event-free survival following transplantation was influenced by the number of chemotherapy failures and the patient's response to conventional salvage therapy prior to transplant. The 16 patients who were transplanted at first relapse, while still responsive to standard therapy, had a 64% actuarial probability of event-free survival at 3 years. Age, presence of extranodal disease, preparative regimen, and type of graft (autologous v allogeneic) were not significant prognostic factors. The majority of transplant-related deaths were from interstitial pneumonitis; inadequate pulmonary function, multiple prior chemotherapy regimens, and prior chest irradiation all appeared to increase the transplant-related mortality. These results suggest a role for marrow transplantation in a subset of patients with relapsed Hodgkin's disease who are unlikely to be otherwise cured but are still responsive to conventional-dose cytoreductive therapy.

High-dose therapy followed by autologous hematopoietic stem-cell infusion for patients with multiple myeloma.

PURPOSE: To evaluate the outcome of patients with multiple myeloma (MM) who received high-dose therapy followed by autologous bone marrow (BM) or peripheral-blood stem-cell (PBSC) infusion. PATIENTS AND METHODS: Sixty-three consecutive patients with MM received autologous BM (n = 13) or PBSC with or without BM (n = 50) following regimens that contained busulfan (Bu) and cyclophosphamide (Cy) (n = 18), modified total-body irradiation (TBI) followed by Bu and Cy (n = 36), or Bu, melphalan, and thiotepa (n = 9). Two thirds of the patients had resistant disease and 69% had received more than 6 months of previous chemotherapy. RESULTS AND CONCLUSION: Recovery of peripheral-blood cell counts was more rapid in patients who received PBSC with or without BM than in patients who received BM alone. Sixteen of 63 patients (25%) died of complications of treatment within 100 days. Nineteen (40%) of 48 assessable patients achieved a complete response (CR), 23 (48%) had a partial response (PR), and six (12%) had no response. The probabilities of survival and survival without relapse or progression for all 63 patients at 3.0 years were .43 and .21, respectively. The probability of relapse or progression at 3 years was .69, and 17 patients (27%) have died of progressive MM. The probabilities of survival and relapse-free survival at 3 years for the 19 patients who achieved a CR were .42 and .17, respectively. In the multivariate analysis, beta2-microglobulin levels more than 2.5 micrograms/mL, more than two regimens of prior therapy and eight cycles of treatment, time to transplant longer than 3 years from diagnosis, and prior radiation were associated with adverse outcomes. Additional strategies, such as intervention earlier in the disease course, improved treatment regimens, sequential high-dose treatments, and posttransplant therapies may improve outcome of selected patients with MM.

Platelet transfusion for patients with cancer: clinical practice guidelines of the American Society of Clinical Oncology.

OBJECTIVE: To determine the most effective, evidence-based approach to the use of platelet transfusions in patients with cancer. OUTCOMES: Outcomes of interest included prevention of morbidity and mortality from hemorrhage, effects on survival, quality of life, toxicity reduction, and cost-effectiveness. EVIDENCE: A complete MedLine search was performed of the past 20 years of the medical literature. Keywords included platelet transfusion, alloimmunization, hemorrhage, threshold and thrombocytopenia. The search was broadened by articles from the bibliographies of selected articles. VALUES: Levels of evidence and guideline grades were rated by a standard process. More weight was given to studies that tested a hypothesis directly related to one of the primary outcomes in a randomized design. BENEFITS/HARMS/COST: The possible consequences of different approaches to the use of platelet transfusion were considered in evaluating a preference for one or another technique producing similar outcomes. Cost alone was not a determining factor. RECOMMENDATIONS: Appendix A summarizes the recommendations concerning the choice of particular platelet preparations, the use of prophylactic platelet transfusions, indications for transfusion in selected clinical situations, and the diagnosis, prevention, and management of refractoriness to platelet transfusion. VALIDATION: Five outside reviewers, the ASCO Health Services Research Committee, and the ASCO Board reviewed this document. SPONSOR: American Society of Clinical Oncology

Human multilineage progenitor cell sensitivity to 4-hydroperoxycyclophosphamide.

This institution has documented consistent reconstitution of hematopoiesis in patients treated with marrow lethal chemoradiotherapy who are "rescued" by reinfusion of autologous cryopreserved marrow cells incubated with 4-hydroperoxycyclophosphamide (4-HC) for in vitro purging of occult tumor cells. After 4-HC incubation, the reinfusion marrow cells showed marked reduction in committed progenitor cell (BFU-E, CFU-GM) frequency, and often total absence of detectable progenitors, without significant loss of marrow reconstituting ability. Since BFU-E and CFU-GM assays did not predict marrow reconstituting ability after 4-HC incubation, we sought to determine whether multilineage progenitor cells (CFU-GEMM) might be more resistant to 4-HC incubation and therefore a more reliable predictive assay in this setting. We found that BFU-E, CFU-GM, and CFU-GEMM all show similar dose-related sensitivity to in vitro incubation with 4-HC and do not appear representative of the cell(s) responsible for marrow reconstitution.

Antigenic analysis of hematopoiesis. V. Characterization of My-10 antigen expression by normal lymphohematopoietic progenitor cells.

The My-10 glycoprotein is an hematopoietic cell surface antigen expressed specifically by undifferentiated (blast) cells, constituting 1%-4% of normal adult bone marrow leukocytes. We used several immunological and in vitro culture methods to analyze the expression of this unique antigen on a variety of lymphohematopoietic progenitor cells. Colony-forming cells (CFC) for granulocyte-monocyte colonies (CFC-GM) and erythroid colonies (BFU-E) were predominantly My-10 positive. CFC with higher proliferative potential were more strongly My-10 positive than CFC with lower proliferative potential, and those for mixed-lineage and blast cell colonies were even more uniformly My-10 positive. Cells maintaining CFC-GM number in short-term marrow culture (pre-CFC) were found to be My-10 positive, as were lymphoid precursors defined by their content of intranuclear terminal deoxynucleotidyl transferase. More mature erythroid precursors (CFU-E) were heterogeneous for antigen expression and lost My-10 antigen progressively, in parallel with advancing maturational stage. The My-10 antigen permits rapid identification and purification of hematopoietic progenitor cells for further study or potential clinical application. The disappearance of the My-10 antigen, moreover, may be a probe for differentiation-linked cellular events.

Dye-mediated photolysis of normal and neoplastic hematopoietic cells.

The purpose of this study was to determine the sensitivity to merocyanine 540 (MC 540)-mediated photolysis of normal human hematopoietic progenitor cells and four leukemia cell lines (Daudi, Raji, K562 and HL-60). Late erythroid progenitors were the most sensitive normal cells. Early erythroid progenitors were of intermediate sensitivity. Granulocyte/macrophage progenitors and multipotent progenitors were the least sensitive normal marrow cells. A combination of dye concentration, serum concentration, and illumination that eliminated 50% of multipotent progenitor cells reduced the concentration of leukemic cells by greater than or equal to 4.5 log. It is conceivable that this difference in photosensitivity can be exploited for the extracorporeal purging of autologous remission marrow grafts.

Long-term follow-up of intensive ara-C-based chemotherapy followed by bone marrow transplantation for adult acute lymphoblastic leukemia: impact of induction Ara-C dose and post-remission therapy.

We report single institution outcome of brief, intensive ara-C-based chemotherapy using bone marrow transplantation as primary intensification for untreated adult patients with acute lymphoblastic leukemia (ALL). Overall disease-free and overall survival were inferior to those reported with prolonged chemotherapy modeled on pediatric protocols. Survival and disease-free survival were superior for patients receiving allogeneic BMT compared with chemopurged autologous transplant or maintenance chemotherapy (patients ineligible for or declining BMT). In multivariate analysis, non-L2-FAB, higher ara-C dose, absence of CNS disease, non-Ph1+ karyotype, allogeneic BMT, T cell phenotype, and younger age were associated with improved disease-free survival. Autologous BMT was not superior to chemotherapy, and appears unlikely to provide adequate curative treatment for most adult ALL patients if not followed by maintenance.

Hematopoietic stem cell transplantation between red cell incompatible donor-recipient pairs.

Transplantation between red cell-disparate donor and recipient is feasible with minimal increase in the risk of transplantation if consideration is given to the immunohematological consequences of the transplant. The risks of immediate and delayed hemolysis must be managed. Some recipients will experience a delay in the recovery of red blood cells.

Effect of DMSO exposure without cryopreservation on hematopoietic progenitor cells.

Colligative cryoprotectants must be non-toxic at the high concentrations required for protection of cells from freeze-injury. Human hematopoietic stem cells are usually cryopreserved in a solution containing 1.6 molal (10% v/v) DMSO. We studied the chemical toxicity of this agent to myeloid and erythroid progenitor cells from healthy donors. No DMSO toxicity was found at concentrations of 5% or 10% at either 4 degrees or 37 degrees C for incubation durations up to 1 h. DMSO at 20% did not decrease the number of progenitor cell-derived colonies per 5 x 10(4) cells cultured, but did result in cell clumping during DMSO washout, resulting in a net loss of progenitor cells. At a concentration of 40% DMSO, a direct toxicity to hematopoietic progenitors was found. Delay in removal of DMSO after thawing of cryopreserved cells for periods up to 1 h was also non-toxic to hematopoietic progenitor cells. Direct addition of DMSO at 1% or 10% final concentration (v/v) to the culture dishes suppressed colony formation. These data suggest that DMSO is not toxic to haematopoietic progenitor cells after short-term exposure at the concentrations used for cryopreservation of marrow and peripheral blood stem cells.

Transplantation of ABO-incompatible bone marrow and peripheral blood stem cell components.

Hemolysis may occur during infusion of an ABO-incompatible HSC component if the recipient has isoagglutinins directed against donor red blood cells, or later as a result of the production by donor lymphocytes of isoagglutinins directed against recipient ABO-antigens. Peripheral blood stem cell (PBSC) components collected by apheresis contain few red cells but considerably greater numbers of lymphocytes than marrow. We reviewed the transplant courses of 158 recipients of marrow (n = 90) or PBSC (n = 68) from HLA-identical, ABO-incompatible sibling donors. No patient experienced immediate or delayed hemolysis attributable to the ABO incompatibility. Recipients of minor ABO-incompatible red cell-replete marrow required fewer red cell transfusions during the first week after transplantation than recipients of PBSC or marrows depleted of red cells; the red cell transfusion requirements for the following 3 weeks did not differ. The maximum level of bilirubin did not differ for patients classified by ABO incompatibility or source of HSC. The development of positive antiglobulin tests occurred for eight marrow recipients from a separate group of 22 patients (17 marrow, five PBSC) for whom this testing was performed. None of these patients developed overt hemolysis. These data indicate that hemolysis complicating ABO-incompatible transplantation is not common after either marrow or PBSC transplantation. Bone Marrow Transplantation (2000) 26, 749-757.

Correlation of hematologic recovery with CFU-GM content of autologous bone marrow grafts treated with 4-hydroperoxycyclophosphamide. Culture after cryopreservation.

We previously described an exponential correlation of the CFU-GM content of 4-hydroperoxycyclophosphamide-treated autologous bone marrow grafts and the rate of hematologic recovery of the recipients after transplantation. Those grafts were assayed before cryopreservation. We now describe a similar analysis based upon cultures of the thawed bone marrow. In a proportional hazards model, the CFU-GM content of the grafts sampled after thawing predicted time to achieving a peripheral blood count of 1 X 10(9)/l leukocytes, 0.5 X 10(9)/l granulocytes, 2% reticulocytes, and last platelet transfusion (p less than 0.001). Using linear regression analysis, the logarithm of the CFU-GM content/kg of recipient weight also was correlated with the time to achieving 1 X 10(9)/l leukocytes (r = -0.62), and 0.5 X 10(9)/l granulocytes (r = -0.66). The hazard ratios (Cox model) and regression coefficients (linear regression model) for the equations calculated from the post-thaw cultures were usually smaller than the corresponding coefficients based upon the pre-freeze cultures, suggesting that pre-freeze cultures may be more accurate predictors of aplasia duration. However, patients with poor post-freeze survival of CFU-GM were more likely to experience delayed engraftment. Therefore, the correlation of post-thaw cultures with engraftment may permit the analysis of cryopreservation techniques.

Treating refractory chronic graft-versus-host disease with extracorporeal photochemotherapy.

Extracorporeal photochemotherapy (ECP; photopheresis), an immunomodulatory therapy, has previously demonstrated promising results in treating chronic graft-versus-host disease (cGvHD). We treated six patients (ages 33-54 years) with long-standing refractory extensive-stage cGvHD. ECP was performed thrice weekly initially in all patients. Concomitant therapies included prednisone (n=6), tacrolimus (n=5), cyclosporin A (n=2), hydroxychloroquine (n=2), mycophenolate mofetil (n=1), and psoralen plus ultraviolet A radiation (n=1). After an average of 7.2 months (range, 2-13 months) of ECP, all patients experienced either improvement or stabilization in sclerodermatous skin changes, as well as partial improvements in liver enzyme levels. Skin softening occurred in four patients and was noted as early as 3-8 weeks into treatment. Two patients were able to taper steroid therapy, and two patients were able to taper ECP to twice weekly. ECP was well tolerated. Our results support those of previous studies, suggesting that ECP may be beneficial in patients with refractory cGvHD.

A randomized phase III clinical trial of autologous blood stem cell transplantation comparing cryopreservation using dimethylsulfoxide vs dimethylsulfoxide with hydroxyethylstarch.

Hematopoietic stem cells intended for autologous transplantation are usually cryopreserved in solutions containing 10% dimethylsulfoxide (DMSO, v/v) or 5% DMSO in combination with 6% hydroxyethylstarch (HES, w/v). We performed a single-blinded, randomized study comparing these cryoprotectant solutions for patients undergoing autologous peripheral blood stem cell (PBSC) transplantation. A total of 294 patients were evaluable; 148 received cells frozen with 10% DMSO and 146 received cells frozen in 5% DMSO/6% HES. Patients who received cells frozen with the combination cryoprotectant recovered their white blood cell count >or=1.0 x 10(9)/l at a median of 10 days, one day faster than those who received PBSC frozen with DMSO alone (P=0.04). Time to achieve neutrophil counts of >or=0.5 x 10(9) and >or=1.0 x 10(9)/l were similarly faster for the recipients of the cells frozen in the combination solution. This effect was more pronounced for patients who received quantities of CD34+ cells higher than the median for the population. Median time to discontinuation of antibiotic use was also one day faster for the recipients of cells cryopreserved with DMSO/HES (P=0.04). In contrast, median times to recovery of platelet count >or=20 x 10(9)/l were equivalent for each group (10 days; P=0.99) and the median numbers of red cell and platelet transfusions did not differ.

Long-term cryopreservation of bone marrow for autologous transplantation.

Little is known about the effect of long-term cryopreservation on the viability of hematopoietic stem cells (HSC) or on the success of autologous bone marrow transplantation. Although progenitor cell assays such as culture of CFU-GM after thawing can be predictive of engraftment, the most rigorous assay for the cryosurvival of HSC is engraftment after reinfusion of stem cells. We retrospectively evaluated the engraftment data for 36 patients with hematologic malignancies or solid tumors treated at the Fred Hutchinson Cancer Research Center between 1981 and 1993 who received bone marrows stored for 2 years or more. The median duration of cryopreservation for this study group was 2.7 years (range 2.0-7.8). Ninety-seven percent of patients in the study group achieved a granulocyte count of > or = 0.5 x 1.0(9)/1 at a median of 19 days (range 10-115) vs 86% of control group (selected by diagnosis and date of storage) at a median of 20 days (P = 0.14). Seventy percent of patients in the study group achieved a platelet count > or = 20 x 10(9)/1 at a median of 27 days (range 9-69) vs 74% of control group at a median of 23 days (P = 0.47). Also, samples of 28 marrows cryopreserved for a median of 4.4 years (range 2.0-7.8) were cultured to determine if a loss of hematopoietic progenitors relative to duration of storage could be detected. The storage length was not predictive for the quantity of colonies formed (P = 0.57 for BFU-E-derived colonies; P = 0.65 for CFU-GM-derived colonies). We found no consistent detrimental effect of long-term cryopreservation on the success rate of autologous bone marrow transplantation. This report confirms previous reports that marrow cells cryopreserved for several years are capable of engrafting. Therefore, bone marrow cells may be stored at an early appropriate time before the side-effects of multiple cycles of chemotherapy and radiotherapy on hematopoietic tissues are incurred.

Microbial contamination of peripheral blood stem cell collections.

We prospectively evaluated microbiologic cultures for a series of 1263 peripheral blood stem cell harvests collected from 376 sequential patients. The incidence of microbial contamination was 0.23% of all samples, or 47% of samples from patients not receiving systemic antibiotics. This incidence of positive microbial cultures is less than that for cultures of bone marrow (3.8%) after harvesting and before further processing. Of the three positive cultures, two grew coagulase-negative Staphylococcus and the third, Streptococcus viridans. Two patients were reinfused with cultured-positive PBSC components, and neither exhibited the same organism in subsequent blood cultures. Although microbial contamination may occur during peripheral blood stem cell collection and cryopreservation, this report indicates that PBSC contamination does not play a conspicuous role in the infectious complications of PBSC transplantation.

Trafficking of CD34+ cells into the peripheral circulation during collection of peripheral blood stem cells by apheresis.

The number of CD34+ cells collected during apheresis is related to the volume of blood processed. In large-volume apheresis (LVL) procedure, more cells can be collected than were originally present in the peripheral blood at the start of the collection procedure. We prospectively studied the levels of CD34+ cells in the blood and apheresis product during LVL procedures for 21 patients with acute myelogenous leukemia or multiple myeloma. These patients experienced a slow decline in blood CD34+ cell concentrations during the apheresis procedure. No patient demonstrated a sustained rise in CD34+ cell counts as a result of the procedure. The number of CD34+ cells collected exceeded the number calculated to be in the peripheral blood at the start of the procedure by an average of 3.0-fold. The efficiency of collection for CD34+ cells averaged 92.6% and did not vary with speed of blood processing, diagnosis, or mobilization regimen. The calculated release of CD34+ cells from other reservoirs into the peripheral blood averaged 3.71 x 10(6)/min (range, 0.36-13.7 x 10(6)/min), and correlated (r = 0.82) with the concentration of these cells in the peripheral blood at the start of the procedure. These data show that the apheresis procedure used in this study does not affect the release of CD34+ cells in a cytokine-treated patient. LVL will result in collection of larger quantities of CD34+ cells than procedures involving processing of smaller volumes of blood, but the number of cells collected is limited by the rate of release of these cells into the peripheral circulation where they are accessible for collection.

Enumeration of HPC in mobilized peripheral blood with the Sysmex SE9500 predicts final CD34+ cell yield in the apheresis collection.

Enumeration of CD34+ cells in the peripheral blood before apheresis predicts the quantity of those cells collected, although the cytometric techniques used are complex and expensive. We found that a subpopulation of lysis-resistant cells in the peripheral blood, identified by the Sysmex SE9500 and designated as HPC, can serve as a surrogate marker predictive of the yield of CD34+ cells. Spearman's rank statistics were used to examine the correlation between WBC, MNC, HPC and CD34+ cells in the peripheral blood and final CD34+ cell yield for 112 samples of peripheral blood and matching apheresis collections from 66 patients and donors. The results indicate that WBC and MNC in the peripheral blood were poor predictors of CD34 content, while HPC gave a correlation coefficient of 0.62. The positive predictive values of different cutoff levels of HPC in the peripheral blood ranging from 5 to 50 x 106/l increased from 0.80 to 0.93 when the target collection was 1 x 106cells/kg. However, for patients with HPC levels below various cutoff levels, the proportion of the collections not reaching that target goal ranged between 0.36 and 0.43, indicating that most collections will still exceed the target goal of CD34+ cells. When the target collection was 2.5 x 106 CD34+ cells/kg, the positive predictive value was lower and negative predictive value was higher.