Symptomatic BK Virus Infection Is Associated With Kidney Function Decline and Poor Overall Survival in Allogeneic Hematopoietic Stem Cell Recipients.

Nephropathy due to BK virus (BKV) infection is an evolving challenge in patients undergoing hematopoietic stem cell transplantation (HSCT). We hypothesized that BKV infection was a marker of kidney function decline and a poor prognostic factor in HSCT recipients who experience this complication. In this retrospective study, we analyzed all patients who underwent their first allogeneic HSCT at our institution between 2004 and 2012. We evaluated the incidence of persistent kidney function decline, which was defined as a confirmed reduction in estimated glomerular filtration rate of at least 25% from baseline using the Chronic Kidney Disease Epidemiology equation. Cox proportional hazard regression was used to model the cause-specific hazard of kidney function decline, and the Fine-Gray method was used to account for the competing risks of death. Among 2477 recipients of a first allogeneic HSCT, BK viruria was detected in 25% (n = 629) and kidney function decline in 944 (38.1%). On multivariate analysis, after adjusting for age, sex, acute graft-versus-host disease (GVHD), chronic GVHD, preparative conditioning regimen, and graft source, BK viruria remained a significant risk factor for kidney function decline (p < 0.001). In addition, patients with BKV infection and kidney function decline experienced worse overall survival. After allogeneic HSCT, BKV infection was strongly and independently associated with subsequent kidney function decline and worse patient survival after HSCT.

[Mycoplasma genitalium detection and correlation with clinical manifestations in population of the Zulia State, Venezuela]. / Detección de Mycoplasma genitalium y correlación con manifestaciones clínicas en una población del estado Zulia, Venezuela.

Diverse studies demonstrate an association between Mycoplasma genitalium and urogenital pathologies. The aim of this study was to investigate the prevalence of M. genitalium in patients attending gynecological evaluation in private clinics (n = 172). DNA amplification assays of the genes 16S rRNA and MgPa were utilized. The prevalence of M. genitalium in the study population was 7.5%. M. genitalium was detected in 12.1% and 4.1% of the symptomatic and asymptomatic patients, respectively (p = 0.047). The infection was diagnosed in patients with cervicitis (17.2%) and mucopurulent secretion (16.6%) and the highest prevalence of infections was registered in the 31-40 years age group. No significant association between the presence of M.genitalium and individual clinical manifestations or the patients age was showed (p > 0.05). The high prevalence of M. genitalium infections, mostly in patients with clinical manifestations showed in this study, warrants the application of diagnostic strategies in the population to investigate the clinical meaning of these microorganisms and to reevaluate therapeutic schemes against non-gonococcal and non-chlamydial infections.

Treatment of donor graft failure with nonmyeloablative conditioning of fludarabine, antithymocyte globulin and a second allogeneic hematopoietic transplantation.

Graft failure is a life-threatening complication of allogeneic stem cell transplantation (SCT). We assessed the feasibility of performing a second SCT after such failure when fludarabine and antithymocyte globulin (ATG) are used for non-myeloablative conditioning and tacrolimus for graft-versus-host disease (GVHD) prophylaxis. Nine patients with SCTs for various hematologic malignancies were enrolled, eight with primary and one with secondary graft failure. The median time between the first and second SCT was 53 days. Eight patients had the same donor for their second SCT, and one had a cord blood transplant. Three patients were not evaluable because of early death; the other six had evidence of donor cell engraftment. Six of the nine patients developed acute grade II-IV GVHD, the main cause of death. Overall, we found that fludarabine and ATG conditioning before a second SCT allows engraftment of donor hematopoiesis. Future studies should include more intense GVHD prophylaxis.

Microbial contamination of hematopoietic progenitor cell products: clinical outcome.

We reviewed the results of routine microbiological assays of 3078 infused hematopoietic progenitor cell (HPC) products for autologous and allogeneic transplantation between January 2001 and December 2005. Thirty-seven (1.2%) contaminated products were found. All patients receiving contaminated infusions received empirical antibiotic prophylaxis according to the assay result. None of these patients developed a positive blood culture with the same agent, developed infections that could be attributable to the contaminated product or experienced any clinical sequelae. Coagulase-negative Staphylococcus was found in 32 (86.5%) products. Admission lengths and time to engraftment were within the expected time frame for autologous and allogeneic transplants. Microbial contamination of HPC products occurs at a low frequency; prophylactic use of antibiotics based on the microbiological assay appears to be effective in preventing clinical complications.

Fludarabine with pharmacokinetically guided IV busulfan is superior to fixed-dose delivery in pretransplant conditioning of AML/MDS patients.

We hypothesized that IV busulfan (Bu) dosing could be safely intensified through pharmacokinetic (PK-) dose guidance to minimize the inter-patient variability in systemic exposure (SE) associated with body-sized dosing, and that this should improve outcome of AML/MDS patients undergoing allogeneic stem cell transplantation. To test this hypothesis, we treated 218 patients (median age 50.7 years, male/female 50/50%) with fludarabine 40 mg/m2 once daily x4, each dose followed by IV Bu, randomized to 130 mg/m2 (N=107) or PK-guided to average daily SE, AUC of 6000 µM min (N=111), stratified for remission status and allo-grafting from HLA-matched donors. Toxicity and GvHD rates in the groups were similar; the risk of relapse or treatment-related mortality remained higher in the fixed-dose group throughout the 80-month observation period. Further, PK-guidance yielded safer disease control, leading to improved overall and PFS, most prominently in MDS patients and in AML patients not in remission at allogeneic stem cell transplantation. We conclude that AML/MDS patients receiving pretransplant conditioning treatment with our 4-day regimen may benefit significantly from PK-guided Bu dosing. This could be considered an alternative to fixed-dose delivery since it provides the benefit of precise dose delivery to a predetermined SE without increasing risk(s) of serious toxicity and/or GvHD.

High-dose chemotherapy and autologous peripheral blood stem cell transplantation for primary breast cancer refractory to neoadjuvant chemotherapy.

The role of high-dose chemotherapy (HDCT) in patients with refractory breast cancer is not well established. Forty-two female patients (median age of 46 years) with breast cancer refractory to neoadjuvant chemotherapy received HDCT (cyclophosphamide, carmustine and thiotepa) supported by an autologous peripheral blood stem cells transplant. Their disease had been refractory (defined as less than partial response) to one (18 patients) or two (24 patients) regimens of neoadjuvant chemotherapy. Twenty-nine patients had surgery before HDCT. The best response after surgery, HDCT, and radiation therapy was assessed 60 days after transplantation. Thirty patients had complete remission, eight had a PR, one had a minor response, and three had progressive disease. In seven of 13 patients whose disease was inoperable before HDCT, it became operable. After a median follow-up of 42 months, 21 patients were alive, and 15 remained disease free. Five-year overall survival (OS) was 57% (CI, 50-64%), and the estimated 5-year progression-free survival was 40% (CI, 32-48%). Both OS and PFS were better in patients whose disease became operable after chemotherapy than in those whose disease remained inoperable. A randomized study is warranted in this patient population.

Randomized trial of high-dose chemotherapy and blood cell autografts for high-risk primary breast carcinoma.

BACKGROUND: Uncontrolled studies have reported encouraging outcomes for patients with high-risk primary breast cancer treated with high-dose chemotherapy and autologous hematopoietic stem cell support. We conducted a prospective randomized trial to compare standard-dose chemotherapy with the same therapy followed by high-dose chemotherapy. PATIENTS AND METHODS: Patients with 10 or more positive axillary lymph nodes after primary breast surgery or patients with four or more positive lymph nodes after four cycles of primary (neoadjuvant) chemotherapy were eligible. All patients were to receive eight cycles of 5-fluorouracil, doxorubicin (Adriamycin), and cyclophosphamide (FAC). Patients were stratified by stage and randomly assigned to receive two cycles of high-dose cyclophosphamide, etoposide, and cisplatin with autologous hematopoietic stem cell support or no additional chemotherapy. Tamoxifen was planned for postmenopausal patients with estrogen receptor-positive tumors and chest wall radiotherapy was planned for all. All P values are from two-sided tests. RESULTS: Seventy-eight patients (48 after primary surgery and 30 after primary chemotherapy) were registered. Thirty-nine patients were randomly assigned to FAC and 39 to FAC followed by high-dose chemotherapy. After a median follow-up of 6.5 years, there have been 41 relapses. In intention-to-treat analyses, estimated 3-year relapse-free survival rates were 62% and 48% for FAC and FAC/high-dose chemotherapy, respectively (P =.35), and 3-year survival rates were 77% and 58%, respectively (P =.23). Overall, there was greater and more frequent morbidity associated with high-dose chemotherapy than with FAC; there was one septic death associated with high-dose chemotherapy. CONCLUSIONS: No relapse-free or overall survival advantage was associated with the use of high-dose chemotherapy, and morbidity was increased with its use. Thus, high-dose chemotherapy is not indicated outside a clinical trial.

Phase I pharmacokinetic study of multicycle high-dose carboplatin followed by peripheral-blood stem-cell infusion in patients with cancer.

PURPOSE: To examine the feasibility of escalating carboplatin area under the concentration-time curve (AUC), using dose predictions based on individual estimates of drug clearance, in a phase I trial of multicycle carboplatin, paclitaxel, and cyclophosphamide chemotherapy with peripheral-blood stem-cell (PBSC) replacement. PATIENTS AND METHODS: Forty-four patients (37 breast, seven ovarian) received 165 courses. Initial target carboplatin AUC was 10 mg/ml x min, with interpatient escalation in increments of 25%. Initial carboplatin dose estimates used creatinine clearance (CrCl) to estimate carboplatin clearance. Subsequent clearance and dose estimates were determined using a model incorporating Bayesian estimation and two measured carboplatin plasma ultrafiltrate concentrations. RESULTS: Median clearance was 80.5 mL/min/m2 (range, 41.6 to 131.8). Carboplatin doses up to 2,440 mg/m2 per course were administered without major extramedullary toxicity. Doses varied 2.6-fold at each exposure level. Using the Bayesian model, AUC was predicted with a mean accuracy of 101.2% (83% using CrCl). Ninety-six of 117 courses were within 25% of the target AUC. This model was less biased (0.15 v -2.35 mg/mL x min) and more precise (2.76 v 3.52) in predicting AUC compared with one using CrCl. Hematologic recovery was not prolonged with increasing exposure. The carboplatin maximum-tolerated systemic exposure (MTSE) was 13.3 mg/mL x min (level five). The dose-limiting toxicity was cardiac toxicity, which occurred at dose levels six and seven. CONCLUSION: Results demonstrate that (1) CrCl is a poor estimator of carboplatin clearance in this population, and (2) the use of a model incorporating limited sampling and Bayesian estimation improves the precision of carboplatin clearance estimation and is suitable for targeting carboplatin exposure in an ambulatory setting.

Allogeneic peripheral-blood progenitor-cell transplantation for poor-risk patients with metastatic breast cancer.

PURPOSE: To evaluate the feasibility of allogeneic peripheral-blood progenitor-cell (PBPC) transplantation and to assess graft-versus-tumor effects in patients with metastatic breast cancer. PATIENTS AND METHODS: Ten patients with metastatic breast cancer that involved the liver or bone marrow were treated with high-dose chemotherapy and allogeneic PBPC transplantation. The median age was 42 years (range, 29 to 55). The median number of metastatic sites was three (range, one to five). The conditioning regimen was cyclophosphamide (6,000 mg/m2), carmustine (BCNU; 450 mg/m2), and thiotepa (720 mg/m2) (CBT regimen). Patients received graft-versus-host disease (GVHD) prophylaxis using cyclosporine- or tacrolimus-based regimens. RESULTS: All patients had engraftment and hematologic recovery. Three patients developed grade > or = 2 acute GVHD and four patients had chronic GVHD. After transplantation, one patient was in complete remission (CR), five achieved a partial remission (PR), and four had stable disease (SD). In two patients, metastatic liver lesions regressed in association with skin GVHD after withdrawal of immunosuppressive therapies. The median follow-up time was 408 days (range, 53 to 605). The median progression-free survival duration was 238 days (range, 53 to 510). CONCLUSION: We conclude that allogeneic PBPC transplantation is a feasible procedure for patients with poor-risk metastatic breast cancer. The regression of tumor associated with GVHD provides suggestive clinical evidence that graft-versus-tumor effects may occur against breast cancer. Compared with autologous transplantation, allogeneic PBPC transplantation is associated with the additional risks of GVHD and related infections. Allogeneic transplantation should only be performed in the context of clinical trials and its ultimate role requires demonstration of improved progression-free survival.

HER-2/neu overexpression as a poor prognostic factor for patients with metastatic breast cancer undergoing high-dose chemotherapy with autologous stem cell transplantation.

PURPOSE: High-dose chemotherapy with autologous stem cell transplantation (HDCT) produces a high tumor response rate for patients with metastatic breast cancer and have 20% long-term progression-free survival. Overexpression of HER-2/neu oncoprotein predicts outcome in patients with breast cancer given standard-dose chemotherapy. Therefore, we evaluated whether the HER-2/neu overexpression in the primary tumor predicts clinical outcome in patients with metastatic breast cancer given HDCT. EXPERIMENTAL DESIGN: A total of 236 patients were given standard-dose induction chemotherapy followed by stem cell collection; high-dose chemotherapy with cyclophosphamide, thiotepa, and carmustine; and stem cell infusion. HER-2/neu expression was assessed by immunostaining with anti-HER-2/neu e2-4001 monoclonal antibody in 63 patients. RESULTS: Clinical characteristics and survival were similar for patients with known and unknown HER-2/neu status. HER-2/neu was overexpressed in 22 of 63 tumors (35%). There was some tendency for HER-2/neu overexpression to be associated with the absence of estrogen or progesterone receptors. In considering the association of HER-2/neu expression with patient outcomes, HER-2/neu overexpression was associated with generally shorter overall survival (P = 0.02) and progression-free survival (P < 0.01), and this association persisted to a lesser extent after adjustment for differences in important prognostic factors between the two groups. CONCLUSION: We conclude that HER-2/neu overexpression may represent an additional prognostic factor for patients with metastatic breast cancer who undergo HDCT.

Low-, medium- and high-dose steroids with or without aminocaproic acid in adult hematopoietic SCT patients with diffuse alveolar hemorrhage.

Diffuse alveolar hemorrhage (DAH) is a poorly understood complication of transplantation carrying a high mortality. Patients commonly deteriorate and require intensive care unit (ICU) admission. Treatment with high-dose steroids and aminocaproic acid (ACA) has been suggested. The current study examined 119 critically ill adult hematopoietic transplant patients treated for DAH. Patients were subdivided into low-, medium- and high-dose steroid groups with or without ACA. All groups had similar baseline characteristics and severity of illness scores. Primary objectives were 30, 60, 100 day, ICU and hospital mortality. Overall mortality (n=119) on day 100 was high at 85%. In the steroids and ACA cohort (n=82), there were no significant differences in 30, 60, 100, day, ICU and hospital mortality between the dosing groups. In the steroids only cohort (n=37), the low-dose steroid group had a lower ICU and hospital mortality (P=0.02). Adjunctive treatment with ACA did not produce differences in outcomes. In the multivariate analysis, medium- and high-dose steroids were associated with a higher ICU mortality (P=0.01) as compared with the low-dose group. Our data suggest that treatment strategies may need to be reanalyzed to avoid potentially unnecessary and potentially harmful therapies.

Comparison of outcomes at two institutions of patients with ALL receiving ex vivo T-cell-depleted or unmodified allografts.

We compared outcomes of adult patients receiving T-cell-depleted (TCD) hematopoietic SCT (HCT) without additional GVHD prophylaxis at Memorial Sloan Kettering Cancer Center (MSKCC, N=52), with those of patients receiving conventional grafts at MD Anderson Cancer Center (MDACC, N=115) for ALL in CR1 or CR2. Patients received myeloablative conditioning. Thirty-nine patients received anti-thymocyte globulin at MSKCC and 29 at MDACC. Cumulative incidence of grades 2-4 acute (P=0.001, 17.3% vs 42.6% at 100 days) and chronic GVHD (P=0.006, 13.5% vs 33.4% at 3 years) were significantly lower in the TCD group. The non-relapse mortality at day 100, 1 and 3 years was 15.4, 25.0 and 35.9% in the TCD group and 9.6, 23.6 and 28.6% in the unmodified group (P=0.368). There was no difference in relapse (P=0.107, 21.3% vs 35.5% at 3 years), OS (P=0.854, 42.6% vs 43.0% at 3 years) or RFS (P=0.653, 42.8% vs 35.9% at 3 years). In an adjusted model, age >50, cytogenetics and CR status were associated with inferior RFS (hazard ratio (HR)=2.16, P=0.003, HR=1.77, P=0.022, HR=2.47, P<0.001), whereas graft type was NS (HR=0.90, P=0.635). OS and RFS rates are similar in patients undergoing TCD or conventional HCT, but TCD effectively reduces the rate of GVHD.

Phase I/II study of dose-intense doxorubicin/paclitaxel/cyclophosphamide with peripheral blood progenitor cells and cytokine support in patients with metastatic breast cancer.

Relapse following complete remission achieved with a single course of high-dose chemotherapy continues to be the main cause of treatment failure in patients with metastatic breast cancer. A phase I/II trial was initiated that combined the two most active drugs against breast cancer, doxorubicin and paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ), with cyclophosphamide, and delivered four cycles of these drugs with peripheral blood progenitor cells (PBPCs) and granulocyte colony-stimulating factor support in an outpatient setting. Patients with untreated metastatic breast cancer received two cycles of doxorubicin 60 mg/m2 and paclitaxel 200 mg/m2. During recovery from the second cycle, PBPCs were harvested. Responding patients were then admitted for a day to receive escalating-dose doxorubicin, paclitaxel, and cyclophosphamide followed by PBPC reinfusion on day 3 as outpatients. Seventeen patients have been enrolled to date. Ten patients completed treatment and received 34 cycles of high-dose chemotherapy every 21 days (range, 21 to 28 days). The median age was 47 years (range, 26 to 56 years) and the median number of metastatic sites was two (range, one to three). Five patients had received adjuvant chemotherapy (four cyclophosphamide/methotrexate/5-fluorouracil and one mitoxantrone-based). The most common toxic reactions were nausea and vomiting (75% of courses) and neurosensory (50% of courses). No patients had a decreased ejection fraction or overt congestive heart failure. Ten patients underwent cardiac biopsy (median doxorubicin, 253 mg/m2; range, 120 to 312 mg/m2); only one showed grade 1 cytotoxic changes with doxorubicin 240 mg/ m2. Six patients were admitted for neutropenic fever. Eight of 10 patients responded (two pathologically confirmed complete remissions in liver). At these doses, four cycles of doxorubicin, paclitaxel, and cyclophosphamide with PBPC and granulocyte colony-stimulating factor support every 21 days was well tolerated and showed evidence of activity. Enrollment at higher dose levels continues so that maximum tolerated dose can be defined.

Factors affecting progression-free survival in hormone-dependent metastatic breast cancer patients receiving high-dose chemotherapy and hematopoietic progenitor cell transplantation: role of maintenance endocrine therapy.

We retrospectively analyzed the effect of maintenance endocrine therapy (MET) after high-dose chemotherapy with hematopoietic progenitor cell transplant (HDCT) on the progression-free survival (PFS) of patients with hormone-dependent metastatic breast cancer (MBC). One hundred and nine consecutive patients with estrogen receptor (ER) and/or progesterone receptor (PgR)-positive MBC, who were progression free for at least 4 months after HDCT with cyclophosphamide, carmustine and thiotepa (CBT), were analyzed. Of these, 55 were non-randomly submitted to MET. After a median follow-up of 34.4 months (17.1-91.0), univariate analysis showed that MET was significantly associated with improved median PFS (31.1 vs 19.2 months, P = 0.022). Complete response to HDCT, pattern of metastatic spread, extent of the disease, single vs multiple metastatic sites, prior endocrine therapy for metastatic disease and prior exposure to any hormonal therapy (adjuvant and/or for the advanced disease) were also associated with PFS at univariate analysis. A multivariate Cox proportional hazard model was fitted to the data in order to correct the effect of MET for the other significant covariates. After correcting for these covariates, MET was still significant, predicting improved PFS (hazard ratio (HR) 0.580, 95% CI; 0.362-0.931). Administration of MET after optimal cytoreduction might result in increased efficacy of HDCT in hormone-dependent metastatic breast cancer.

Graft-versus-leukemia effect after allogeneic bone marrow transplantation for chronic lymphocytic leukemia.

We report the case of a patient with chronic lymphocytic leukemia (CLL) with persistent lymphocytosis and lymphadenopathy after allogeneic bone marrow transplantation (BMT). After receiving a donor lymphocyte infusion on day 87 he achieved complete remission upon development of chronic graft-versus-host disease, suggesting that a graft-versus-leukemia effect is operative in this malignancy.

Idiopathic pneumonia syndrome after high-dose chemotherapy and autologous hematopoietic stem cell transplantation for high-risk breast cancer.

Our aim was to describe the incidence, clinical course, and risk factors for idiopathic pneumonia syndrome (IPS) after high-dose chemotherapy with cyclophosphamide, carmustine, and thiotepa followed by autologous stem cell transplantation for high-risk breast cancer. Charts for patients who underwent high-dose chemotherapy for high-risk breast cancer at a single center from 1992 to 2000 were retrospectively reviewed, and potential risk factors for development of IPS were sought with the log-rank test. Of 164 patients reviewed, 20 developed IPS at a median onset of 87 days after the transplant (range, 2-257 days). The actuarial incidence of IPS in the first 100 days after the transplant was 8%, and 95% of patients developed symptoms within the first 6 months after transplant. Patient age, smoking status, breast cancer stage at diagnosis, and pretransplant lung function did not predict development of IPS. Three patients died of progressive pulmonary failure and the IPS resolved in the other 17. We concluded that IPS is an important cause of morbidity and mortality in patients with high-risk breast cancer undergoing high-dose chemotherapy. Given the absence of predictive factors, any pulmonary symptoms appearing in the first year after the transplant should be evaluated carefully.

Management of lymphoma recurrence after allogeneic transplantation: the relevance of graft-versus-lymphoma effect.

Donor lymphocyte infusions, by virtue of a graft-versus-tumor effect, have been shown to induce remissions in leukemia that recurs after allogeneic bone marrow transplantation. Similar effects have been postulated to contribute to the decreased recurrence rate observed after allogeneic transplantation in non-Hodgkin's lymphoma. This lower recurrence rate may be due to a variety of other mechanisms. We aimed to evaluate the role of graft-versus-lymphoma effects in patients in whom lymphomas recur after allogeneic transplantation. At the time of recurrence, immunosuppressive therapy was withheld. Patients with non-responding disease received an infusion of donor lymphocytes. Patients were observed for response and graft-versus-host disease. Disease in four of nine patients responded to withdrawal of immunosuppressive therapy. A minor response was observed in one of three recipients of donor lymphocyte infusions. Responses were observed among two patients with follicular lymphoma, one with large cell lymphoma and one with lymphoblastic lymphoma. A minor response was observed in a patient with prolymphocytic leukemia/lymphoma. We conclude that withdrawal of immunosuppressive therapy and donor lymphocyte infusion can induce durable remissions in patients with recurrent lymphoma after allogeneic transplantation.

High-dose chemotherapy with hematopoietic stem-cell transplantation for breast cancer: current status, future trends.

High-dose chemotherapy with hematopoietic stem-cell transplantation (HDC/HSCT) has been extensively studied as a potential treatment for breast cancer. A literature search of MEDLINE from January 1990 through December 1999 identified 497 published full papers. Of these articles, 120 reported the results of clinical trials, 78 were reviews, and 299 reported on issues related to the technology of peripheral stem cells, supportive care, and toxicity. The phase II data must be interpreted with caution, as it is subject to selection bias; transplant recipients tended to be younger, rigorously staged, and selected to be chemotherapy responsive. There continues to be controversy regarding the role of high-dose therapy in this disease. Only a few fully published randomized trials are available; these studies were powered only to detect large differences in survival and no benefit was shown. Several large controlled trials are either in progress or are too early for definitive analysis. This review analyzes the current literature on HDC/HSCT for breast cancer, identifying prognostic factors and discussing ongoing research designed to improve antitumor effects.

Analysis of chimerism following allogeneic bone marrow transplantation by fluorescent-in-situ hybridization.

Twelve patients (9 males and 3 females) with chronic myelogenous leukemia, underwent CD8+ T cell depleted allogeneic bone marrow transplantation with a sex-mismatched donor. To assess chimerism we performed fluorescent in-situ hybridization for the X and Y chromosome at different time points after BMT. Patient median age was 33 years (range, 27-48); median time to transplant was 28 months (range, 5-87). All patients received thiotepa 10 mg/kg; cyclophosphamide 120 mg/kg and 12.0 Gy of fractionated total body irradiation. CD8+ cells were depleted from the normal donor marrow with anti-CD8 murine monoclonal antibodies and immunomagnetic beads. Bone marrow aspirates were studied at <60, 60-140, 140-300, and >300 days post BMT. Hybridization was done on mononuclear cells and a median of 518 cells were counted per slide with a fluorescent microscope. The median percentage of donor cells was 99.04%, 98.21%, 98.15%, and 99.52% at <60, 60-140, 140-300, and >300 days after BMT. Mixed chimerism was a rare occurrence after CD8 depleted allogeneic BMT and occured only at low levels. Inhibition of repopulation by host hematopoietic cells may be associated with the graft-versus-leukemia effect against CML.