Phase I trial of plerixafor combined with decitabine in newly diagnosed older patients with acute myeloid leukemia.

Acute myeloid leukemia carries a dismal prognosis in older patients. The objective of this study was to investigate the safety and efficacy of decitabine combined with the CXCR4 antagonist plerixafor in newly diagnosed older patients with acute myeloid leukemia and to evaluate the effects of plerixafor on leukemia stem cells. Patients were treated with monthly cycles of decitabine 20 mg/m2 days 1-10 and escalating doses of plerixafor (320-810 mcg/kg) days 1-5. Sixty-nine patients were treated, with an overall response rate of 43%. Adverse karyotype did not predict response (P=0.31). Prior hypomethylating agent treatment was the strongest independent predictor of adverse overall survival (hazard ratio 3.1; 95%CI: 1.3-7.3; P=0.008) and response (14% in previously treated patients, 46% in treatment naïve; P=0.002). As expected, the most common toxicities were myelosuppression and infection. Plerixafor induced mobilization of leukemia stem and progenitor cells, but did not cause clinically significant hyperleukocytosis. Reduction in leukemia stem cells appeared to correlate with duration of response. Plerixafor can be safely added to decitabine in poor-prognosis, elderly acute myeloid leukemia patients. The maximum tolerated dose of the combination was 810 mcg/kg. While mobilization of leukemia stem cells was observed in some patients, the clinical benefit of adding plerixafor was uncertain. This trial was registered at clinicaltrials.gov identifier: 01352650.

Safety of anticoagulation in thrombocytopenic patients with hematologic malignancies: A case series.

The incidence of venous thromboembolism is greater among cancer patients than the general patient population, with recurrence rates also much higher in patients with cancer diagnoses. Patients with hematologic malignancies often experience prolonged periods of thrombocytopenia throughout their disease course, making therapeutic anticoagulation a challenge. We describe 13 cases of patients with hematologic malignancies that were therapeutically anticoagulated with either low-molecular-weight heparin or unfractionated heparin during periods of severe thrombocytopenia (platelet counts < 50 × 109/µL). Patients were included if they had a diagnosis code for a hematologic malignancy and venous thromboembolism between 1 January 2010 and 31 December 2012. The diagnosis of venous thromboembolism included both deep vein thrombosis and pulmonary embolism. There was one bleeding event, World Health Organization grade 2, that was documented in a patient receiving enoxaparin dosed twice daily, resulting in an overall bleeding rate of 7.7% in this case series. All 13 patients were administered platelet transfusions during the periods of severe thrombocytopenia. While each patient case must have the risks and benefits weighed individually, we observed that anticoagulation for the treatment of venous thromboembolism during periods of thrombocytopenia may be considered in patients with hematologic malignancies.

Phase 1 study of epigenetic priming with decitabine prior to standard induction chemotherapy for patients with AML.

We conducted an open-label phase 1 study exploring the feasibility, safety, and biologic activity of epigenetic priming with decitabine before standard induction chemotherapy in patients with less-than-favorable risk of acute myelogenous leukemia (AML). We directly compared the clinical and DNA-hypomethylating activity of decitabine delivered at 20 mg/m² by either a 1-hour infusion (Arm A) or a continuous infusion (Arm B) for 3, 5, or 7 days before a single, standard induction with infusional cytarabine (100 mg/m² for 7 days) and daunorubicin (60 mg/m² × 3 doses). Toxicity was similar to that of standard induction chemotherapy alone. Although we did not identify a maximum tolerated dose, there was more gastro-intestinal toxicity with 7 days of decitabine priming. Decitabine induced DNA hypomethylation at all dose levels and there was a trend toward greater hypomethylation in CD34(+) bone marrow cells when decitabine was delivered by a short pulse (Arm A). Twenty-seven subjects (90%) responded to therapy: 17 with complete remission (57%) and 10 with partial remission (33%). Of the patients with partial remission to protocol treatment, 8 achieved remission to their next therapy, bringing the overall complete remission rate to 83%. We conclude that epigenetic priming of intensive chemotherapy can be safely delivered in an attempt to improve response rates. This trial was registered at www.clinicaltrials.gov as NCT00538876.

A phase III study of infliximab and corticosteroids for the initial treatment of acute graft-versus-host disease.

Anti-Tumor Necrosis Factor Alpha (TNF-alpha) therapy with infliximab has shown to be effective for patients with steroid-refractory acute graft-versus-host disease (aGVHD). An open-labeled, phase III trial was conducted to determine if the addition of infliximab to steroids could improve results for patients with newly diagnosed grade II-IV aGVHD. A total of 63 patients were randomized either to 2 mg/kg/day methylprednisolone (MP) or infliximab+ MP. Average age was 47 years (range: 20-70 years); 64% were male. Fifty-three percent and 51% of patients received a matched-sibling and/or bone marrow (BM) graft. Sixty-seven percent had grade II, 33% grade III-IV aGVHD; 62% had skin, 53% gastrointestinal (GI), and 7% had liver involvement. At days 7 and 28, the response rate for infliximab+ MP versus MP was 52% versus 78%, P=.03 and 62% versus 58%, P=.7, respectively. Cumulative incidences of GVHD-related mortality, nonrelapse mortality (NRM), and overall survival (OS) were not significantly different between the 2 groups (GVHD-related mortality: 38% versus 32%, P=.6; NRM: 52% versus 36%, P=.3; OS: 17% and 28%, P=.4 for infliximab+ MP versus MP, respectively). Patients with newly diagnosed aGVHD derive no benefit from the addition of anti-TNF-alpha therapy with infliximab when compared to corticosteroids alone.

Caspofungin as primary antifungal prophylaxis in stem cell transplant recipients.

STUDY OBJECTIVES: To assess the effectiveness and tolerability of caspofungin as primary prophylaxis against invasive fungal infections in stem cell transplant recipients who are poor candidates for triazole or lipid amphotericin B prophylaxis due to renal or hepatic dysfunction, and to determine whether any patient characteristics are independently associated with an increased risk of breakthrough invasive fungal infection during caspofungin prophylaxis. DESIGN: Retrospective medical record review. SETTING: Tertiary care comprehensive cancer center. PATIENTS: One hundred twenty-three adult stem cell transplant recipients who received caspofungin 35-50 mg/day for up to 100 days after transplantation as primary antifungal prophylaxis between January 1, 2002, and June 30, 2005. MEASUREMENTS AND MAIN RESULTS: Data were collected on host and transplant characteristics such as transplant type, neutropenia, graft-versus-host disease (GVHD), and corticosteroid use, as well as evidence of breakthrough invasive fungal infections. Of the 123 patients, 117 (95.1%) were allogeneic recipients, and the median time to engraftment was 12 days (range 6-26 days). Fifty (40.7%) of the patients developed GVHD of grade 2 or greater and received corticosteroids for more than 21 days. Median duration of caspofungin prophylaxis was 73 days (range 10-100 days). Nine patients (7.3%) developed breakthrough invasive fungal infections (two cases of mixed Aspergillus species and one each of Aspergillus terreus, Rhizopus, Exserohilum, an unspecified mold, Cryptococcus, Candida glabrata, and Candida tropicalis). Median time to invasive fungal infection development was 65 days (range 12-88 days). Only one case occurred during the neutropenic period before engraftment. Multivariate analysis showed that Pseudomonas coinfection (p=0.04) and infliximab therapy (p=0.02) were associated with breakthrough invasive fungal infections in patients receiving caspofungin. By day 100, there were five (4.1%) deaths, two of which were directly attributable to invasive fungal infections. No caspofungin-related adverse events were reported. CONCLUSION: Caspofungin seems to be an effective and well-tolerated option for primary antifungal prophylaxis in the highly immunosuppressed stem cell transplant patient population.

Early human herpes virus type 6 reactivation in umbilical cord blood allogeneic stem cell transplantation.

Human herpes virus type 6 can reactivate in patients after allogeneic stem cell transplantation and has been associated with serious sequelae such as delayed engraftment and an increased risk of developing acute graft-versus-host disease (GVHD). This study investigated human herpes virus type 6 (HHV-6) reactivation within 60 days of transplantation in stem cell transplants utilizing single umbilical cord blood, double umbilical cord blood, or umbilical cord blood plus haploidentical stem cells. Of 92 patients, 60 (65%) had HHV-6 reactivation. Reactivation was not significantly influenced by any patient characteristics, disease characteristics, or by stem cell source (umbilical cord blood only versus haploidentical plus umbilical cord blood). We did not observe any impact of HHV-6 reactivation on neutrophil or platelet count recovery or on relapse-free survival. HHV-6 reactivation was associated with subsequent development of prerelapse acute GVHD (HR = 3.00; 95% CI, 1.4 to 6.4; p = 0.004).

West Nile encephalitis in 2 hematopoietic stem cell transplant recipients: case series and literature review.

Most human cases of West Nile virus infection are acquired via bites from an infected mosquito. In some cases, infection may also be transmitted by infected blood products or transplanted organs. There have been recent publications suggesting that chemotherapy and immunosuppression may increase a person's risks of developing central nervous system disease if the person is infected with the West Nile virus. Because patients undergoing hematopoietic stem cell transplantation not only are immunocompromised, but also receive multiple blood products, they are at a particularly high risk for acquiring symptomatic disease if exposed to the West Nile Virus. We describe here 2 patients who underwent hematopoietic transplantation at our institution and subsequently developed fatal West Nile virus infections.

High-dose topotecan, melphalan and cyclophosphamide (TMC) with stem cell support: a new regimen for the treatment of multiple myeloma.

The goal of this trial was to assess the toxicity and potential efficacy of high-dose topotecan, melphalan and cyclophosphamide as a preparative regimen for patients with multiple myeloma undergoing autologous stem cell transplantation. Eighteen patients were treated, 8 for first remission consolidation, 4 with relapse sensitive disease, 3 primary refractory and 3 relapsed refractory. The median age was 56 (38 - 65) and the median number of prior regimens was 3 (1 - 8). Patients received cyclophosphamide 1 g/m2/d on days -6, -5, -4; melphalan 70 mg/m2 on days -3, -2 and topotecan 3.0 to 3.5 mg/m2/d on days -6 to -2. Peripheral blood stem cells were infused on day 0. Toxicity (Bearman Toxicity Criteria) was mostly limited to grade 1 - 2 mucositis and grade 1 diarrhea. There were no transplant-related deaths. The overall response rate at 3 months post transplantation was 89% with 17% CR, 2 of those in refractory patients. The overall response rate in refractory patients was 67%. With a median follow up of 12.3 months, 89% of patients are alive. The TMC regimen is well tolerated and produces high response rates. Further evaluation of TMC to fully assess response and survival is ongoing.

Management of acute cancer treatment-induced diarrhea.

OBJECTIVES: To describe the dietary and pharmacologic management of acute CTID. DATA SOURCES: Primary and secondary literature, and clinical experience. CONCLUSION: When dietary strategies do not work, or when patients present with grade 3/4 diarrhea, pharmacologic intervention is required. First-line therapy should be initiated quickly with loperamide or diphenoxylate/atropine in recommended doses. Somatostatin analogues are effective as second-line therapy or as first-line therapy for patients with grade 3/4 diarrhea. IMPLICATIONS FOR NURSING PRACTICE: Oncology nurses should strive to match treatment with the severity of symptoms of CTID. Whatever therapy is chosen, the goal must be to quickly control this debilitating and potentially life-threatening side effect so that primary chemotherapy and/or radiation therapy may be resumed and completed.

Decitabine in patients with newly diagnosed and relapsed acute myeloid leukemia.

Treatment options for older patients with acute myeloid leukemia (AML) and for patients with relapsed/refractory AML are limited, and outcomes are poor. Decitabine, a hypomethylating agent, is active in patients with myelodysplastic syndrome (MDS) and AML, but its optimal dose and schedule are unknown. We report the efficacy and safety of repeated 10-day cycles of decitabine 20 mg/m(2) administered intravenously over 1 h in 52 newly diagnosed and 102 relapsed/refractory patients. Repeated 10-day cycles of decitabine produced a complete response (CR) in 40% of newly diagnosed older patients with AML, many of whom had adverse prognostic features. The median overall survival (OS) was 318 days but there was prolonged survival in responders of 481 days. Relapsed/refractory patients had a CR rate of 15.7% with a median OS of 177 days. Extramedullary toxicity was mild and the regimen was well tolerated for ongoing post-remission, outpatient maintenance cycles. Responses were durable for over 1 year.

Prognostic factors for outcomes of patients with refractory or relapsed acute myelogenous leukemia or myelodysplastic syndromes undergoing allogeneic progenitor cell transplantation.

Allogeneic progenitor cell transplantation is the only curative therapy for patients with refractory acute myelogenous leukemia or myelodysplastic syndromes. To identify prognostic factors in these patients, we performed a retrospective analysis of transplantation outcomes. Patients were selected if they had undergone an allogeneic transplantation between January 1988 and January 2002 and were not in remission or first untreated relapse at the time of transplantation. A total of 135 patients were identified. The median age was 49.5 years (range, 19-75 years). At the time of transplantation, 39.3% of patients had not responded to induction therapy, 37% had not responded to first salvage therapy, and 23.7% were beyond first salvage. Forty-one patients (30%) received unrelated donor progenitor cells. Eighty patients (59%) received either a reduced-intensity or a nonmyeloablative regimen. A total of 104 (77%) of 135 patients died, with a median survival time of 4.9 months (95% confidence interval, 3.9-6.6 months). The median progression-free survival was 2.9 months (95% confidence interval, 2.5-4.2 months). A Cox regression analysis showed that Karnofsky performance status, peripheral blood blasts, and tacrolimus exposure during the first 11 days after transplantation were predictive of survival. These data support the use of allogeneic transplantation for patients with relapsed or refractory acute myelogenous leukemia/myelodysplastic syndromes and suggest that optimal immune suppression early after transplantation is essential for long-term survival even in patients with refractory myeloid leukemias.

Discontinuation of immunosuppression for prevention of kidney graft rejection after receiving a bone marrow transplant from the same HLA identical sibling donor.

Induction of tolerance in solid organ transplant recipients has been a long sought goal so that patients will not need lifelong immunosuppression. In this case report we review a patient who received a kidney transplant from an HLA matched related sibling and developed acute leukemia as a consequence of her immunosuppression. The patient was then treated with an allogeneic bone marrow transplant from her kidney donor. After the bone marrow transplant, all immunosuppression therapy for graft rejection and graft versus host disease was stopped. Six months after the bone marrow transplant, the patient's kidney function had no deterioration as a consequence of stopping immunosuppression. This illustrated that a combined solid organ/bone marrow transplant can help to induce tolerance. In fact, the tolerance to the bone marrow transplant for prevention of graft versus host disease may have been accomplished by the prior kidney transplant.

Tacrolimus-associated posterior reversible encephalopathy syndrome after allogeneic haematopoietic stem cell transplantation.

Neurotoxicity is a significant complication of the use of tacrolimus. From April 1998 to December 2001, we identified 10 patients (six women, four men) who developed 11 episodes of tacrolimus-associated posterior reversible encephalopathy syndrome (PRES) after allogeneic haematopoietic stem cell transplantation for haematological malignancies. The diagnosis was made by characteristic clinical findings (mental status changes, seizures, neurological deficits) with the exclusion of other causes and characteristic imaging findings. The median age was 35.5 years (range 19-57 years). Seven patients received a matched-unrelated donor transplant and three received a cord blood transplant. The overall incidence of PRES was 1.6%, while the incidence in matched-unrelated, mismatched-related and cord blood transplants was 3.5%, 4.9% and 7.1% respectively. Mental status changes, cognitive deficits, seizures and lethargy were the most common clinical findings. Eight of 10 patients had characteristic findings of hyperintensity of the white matter on T2-weighted images and FLAIR (fluid-attenuated inversion recovery) sequence on magnetic resonance imaging of the brain. Serum tacrolimus levels were within the therapeutic range in most patients. Tacrolimus treatment was continued (n = 4) or temporarily withheld (n = 7) for 1-14 d. One patient was changed to cyclosporine. In most patients, subsequent treatment with tacrolimus was well tolerated without recurrence of neurotoxicity.

Tumor necrosis factor-alpha blockade for the treatment of acute GVHD.

Despite posttransplantation immunosuppressive therapy, acute graft-versus-host disease (GVHD) remains a major cause of sickness and death. Tumor necrosis factor-alpha (TNF-alpha) is implicated in the pathophysiology of GVHD at several steps in the process. Infliximab is a genetically constructed immunoglobulin G1 (IgG1) murine-human chimeric monoclonal antibody that binds the soluble subunit and the membrane-bound precursor of TNF-alpha, blocking its interaction with receptors and causing lysis of cells that produce TNF-alpha. In this study we retrospectively evaluated 134 patients who had steroid-refractory acute GVHD. Of these, 21 who received infliximab as a single agent were analyzed. The overall response rate was 67% (n = 14), and 13 patients (62%) experienced complete response (CR). Five patients (24%) did not respond, and 2 (10%) had progressive GVHD. None had a toxic reaction to infliximab. Ten patients (48%) had 18 fungal infections, including Aspergillus species in 7 and Candida species in 10. Seventeen patients (81%) had bacterial infections, including 32 gram-positive and 8 gram-negative infections. Viral infections, primarily cytomegalovirus reactivation, occurred in 14 patients (67%). The Kaplan-Meier estimate of overall survival was 38%. In conclusion, infliximab was well tolerated and active for the treatment of steroid-resistant acute GVHD, particularly with gastrointestinal tract involvement. Survival after steroid-resistant acute GVHD continues to be problematic. The possibility of excessive fungal and other infections must be explored further.

Nonablative versus reduced-intensity conditioning regimens in the treatment of acute myeloid leukemia and high-risk myelodysplastic syndrome: dose is relevant for long-term disease control after allogeneic hematopoietic stem cell transplantation.

Intensity of the preparative regimen is an important component of allogeneic transplantations for myelodysplasia (MDS) or acute myelogenous leukemia (AML). We compared outcomes after a truly nonablative regimen (120 mg/m2 fludarabine, 4 g/m2 cytarabine, and 36 mg/m2 idarubicin [FAI]) and a more myelosuppressive, reduced-intensity regimen (100 to 150 mg/m2 fludarabine and 140 or 180 mg/m2 melphalan [FM]). We performed a retrospective analysis of 94 patients with MDS (n = 26) and AML (n = 68) treated with FM (n = 62) and FAI (n = 32). The FAI group had a higher proportion of patients in complete remission (CR) at transplantation (44% versus 16%, P =.006), patients in first CR (28% versus 3%, P =.008), and HLA-matched sibling donors (81% versus 40%, P =.001). Median follow-up is 40 months. FM was significantly associated with a higher degree of donor cell engraftment, higher cumulative incidence of treatment-related mortality (TRM; P =.036), and lower cumulative incidence of relapse-related mortality (P =.029). Relapse rate after FAI and FM was 61% and 30%, respectively. Actuarial 3-year survival rate was 30% after FAI and 35% following FM. In a multivariate analysis of patient- and treatment-related prognostic factors, progression-free survival was improved after FM, for patients in CR at transplantation, and for those with intermediate-risk cytogenetics. Survival was improved for patients in CR at transplantation. In conclusion, FM provided better disease control though at a cost of increased TRM and morbidity.

Acute and chronic graft-versus-host disease after ablative and nonmyeloablative conditioning for allogeneic hematopoietic transplantation.

In this study, we evaluated the influence of nonmyeloablative and ablative conditioning regimens on the occurrence of acute and chronic graft-versus-host disease (GVHD). One hundred thirty-seven patients undergoing matched-related sibling transplantations received the same GVHD prophylaxis. Myeloablative regimens included intravenous busulfan/cyclophosphamide (n=45) and fludarabine/melphalan (n=29). Patients in the nonmyeloablative group (n=63) received fludarabine/idarubicin/cytarabine, cisplatin/fludarabine/idarubicin, and fludarabine/cyclophosphamide. The actuarial rate of grade II to IV acute GVHD was significantly higher (hazard ratio, 3.6; 95% confidence interval, 1.5-8.8) in patients receiving ablative regimens (36%) compared with the nonmyeloablative group (12%). The cumulative incidence of chronic GVHD was higher in the ablative group (40%) compared with the nonmyeloablative group (14%). The rates were comparable within the first 200 days and were significantly higher in the ablative group beyond day 200 (hazard ratio, 5.2; 95% confidence interval, 1.2-23.2). Nonrelapse and GVHD-related mortality were relatively low in both groups. The use of the described nonmyeloablative preparative regimens was associated with a reduced incidence of grade II to IV acute GVHD and chronic GVHD compared with the busulfan/cyclophosphamide and fludarabine/melphalan transplant regimens. It is interesting to note that nonrelapse mortality with nonmyeloablative regimens in older and more debilitated patients was low (14%) and comparable to that achieved with standard high-dose regimens in younger patients.

Hemorrhagic cystitis after allogeneic hematopoietic stem cell transplantation: donor type matters.

Hemorrhagic cystitis (HC) remains a common complication of allogeneic blood and marrow transplantation. Previous analyses of risk factors for this complication were performed in heterogeneous populations, with dissimilar diagnosis and conditioning regimens. We postulated that HC is more prevalent in matched unrelated donor (MUD) and unrelated cord blood (UCB) transplantations than in matched related donor (MRD) transplantations. We performed a retrospective study on 105 acute lymphocytic leukemia patients treated with 12 Gy total body irradiation-based regimens and allogeneic transplants (MUD, n = 38; UCB, n = 15; mismatched related, n = 20; MRD, n = 32). HC occurred in 16% of patients receiving MRD transplants, 30% of recipients of mismatched related, and 40% of MUD or UCB transplants (hazard ratio 2.9, 95% CI 1.0-7.9 for the comparison of MRD versus MUD). The excessive rate of HC among MUD and UCB patients became evident after the first 30 days after transplantation. Recipients younger than 26 years had a significantly higher incidence of HC (HR 2.5, 95% CI 1.1-5.8). This donor type and age effect was independent of platelet engraftment, development of graft-versus-host disease (GVHD), source of stem cells, use of anti-thymocyte globulin (ATG) or cyclophosphamide in the regimen, steroid use, or stem cell source. We concluded that HC is more prevalent in MUD and UCB transplantations.

Reduced-intensity conditioning for unrelated donor hematopoietic stem cell transplantation as treatment for myeloid malignancies in patients older than 55 years.

Hematopoietic stem cell transplantation from unrelated donors is an effective treatment for myeloid malignancies, but its use is usually restricted to young patients without comorbidities. The development of reduced-intensity preparative regimens has allowed the extension of this form of treatment to older and medically infirm patients. We assessed the outcomes of patients older than 54 years who received unrelated donor transplants for the treatment of myeloid malignancies in our institution. There were 29 patients (median age, 59 years) with advanced acute myeloid leukemia (n = 13), myelodysplastic syndrome (n = 7), and chronic myeloid leukemia (n = 9) included. With a median follow-up of 27 months, the probability of overall and event-free survival, and nonrelapse mortality at one year were 44%, 37%, and 55%, respectively. Grades II to IV acute graft-versus-host disease (GVHD) occurred in 41% of patients and chronic GVHD developed in 63% of patients surviving more than 100 days. Of the 11 survivors, 9 were interviewed and reported good quality of life after transplantation using the Functional Assessment of Cancer Therapy-Bone Marrow Transplant Scale (FACT-BMT) questionnaire, with high scores in all dimensions. Unrelated donor transplantation is a treatment option for older patients with myeloid malignancies. The results in this cohort of patients are comparable with those reported in younger patients with similarly advanced disease.

Use of thrombopoietin in combination with chemotherapy and granulocyte colony-stimulating factor for peripheral blood progenitor cell mobilization.

This phase I/II dose-escalation study examined the safety and efficacy of recombinant human thrombopoietin (rhTPO) and granulocyte colony-stimulating factor (G-CSF) for postchemotherapy mobilization of peripheral blood progenitor cells (PBPCs) in patients with advanced breast cancer. Patients received cyclophosphamide, etoposide, and cisplatin (CVP) followed by G-CSF (6 microg/kg twice a day) and rhTPO (0.6, 1.2, 2.4, or 3.6 microg/kg as a single dose on day 5 or as 3 doses on days 5, 7, and 9 after chemotherapy). PBPCs were collected by daily leukapheresis when the postnadir white blood cell count reached > or = 2 x 10(9)/L; leukapheresis was continued until acquisition of a target dose of > or = 5 x 10(6) CD34+ cells/kg. Mobilized PBPCs were transplanted into patients after additional high-dose chemotherapy with cyclophosphamide, carmustine, and thiotepa (CBT). Comparisons were made with contemporaneously treated, nonrandomized, control patients who received the same chemotherapy regimens and G-CSF support but who did not receive rhTPO. Of 32 evaluable patients receiving rhTPO and G-CSF after CVP, 91% required only 1 leukapheresis to achieve a target PBPC graft; by contrast, only 69% of 36 of the control patients achieved the target graft with just 1 leukapheresis (P = .026). A median of 26.7 x 10(6) CD34 cells/kg per leukapheresis was obtained from the rhTPO-treated patients compared with 11.5 x 10(6) cells/kg per leukapheresis from the controls (P = .09). Higher rhTPO doses appeared to yield more CD34+ cells. When PBPCs were infused after high-dose CBT chemotherapy, the median times to return of an absolute neutrophil count of 0.5 x 10(9)/L and a platelet count of 20 x 10(9)/L were 15 and 16 days, respectively; these values did not differ from those in the control group (15 days for both neutrophil and platelets). No patient developed anti-TPO antibodies. These results indicate that rhTPO safely and effectively augments the number of PBPCs mobilized with chemotherapy and G-CSF and can reduce the required number of leukaphereses. Further studies are also warranted in patients who are likely to experience suboptimal PBPC mobilization when treated with currently available techniques.