Ofatumumab and bendamustine in previously treated chronic lymphocytic leukemia and small lymphocytic lymphoma.

Despite initial responses > 90% with fludarabine and rituximab-based regimens, patients with chronic lymphocytic leukemia (CLL) invariably relapse and require further treatment. Ofatumumab and bendamustine have each shown efficacy in relapsed/refractory CLL with overall response rates (ORRs) of 58% and 76%, respectively. Given excellent data with bendamustine and rituximab in relapsed/refractory CLL/small lymphocytic lymphoma (SLL), this phase II study evaluated the combination of ofatumumab and bendamustine in previously treated patients. Patients received ofatumumab 300 mg intravenously (IV) day - 7, followed by ofatumumab 1000 mg IV day 1 and bendamustine 70 mg/m(2) days 1 and 2 of each 28-day cycle. Patients received 4-6 cycles depending on number of prior therapies, as long as well-tolerated or until progression. Of 10 patients enrolled, the ORR was 40% and complete response rate was 20%. The median progression-free and overall survivals were 8.1 months and 16.2 months. Three patients developed Richter transformation. The study was closed early due to unexpected adverse events including infusion-related reactions, infection and neurotoxicity.

Hepatitis B screening practice among older Chinese in the Greater Washington, DC, area.

OBJECTIVES: Older Chinese Americans are at greater risk of contracting hepatitis B virus (HBV) because they were born before the implementation of universal childhood vaccination policies. This study examined the prevalence of HBV screening, test results, and predictors of HBV screening among older Chinese. METHODS: Two hundred fifty-two Chinese immigrants (older than 50 years) recruited from Chinese-speaking physicians' offices in the Washington, DC, area participated in a cancer screening questionnaire. Descriptive statistics and hierarchical logistic regressions were conducted. RESULTS: Among the 164 participants (65%) who underwent HBV screening, 66% reported that they were susceptible to HBV infection. Stronger self-care beliefs, longer US residency, lower HBV knowledge, and lack of physician recommendations were independently and negatively associated with HBV screening. CONCLUSIONS: Many older Chinese did not adhere to HBV screening guidelines because of cultural views and information deficiency. Culturally appropriate interventions aimed to enhance their knowledge and communication with physicians about HBV are needed for promoting screening.

Promoting Chinese-speaking primary care physicians' communication with immigrant patients about colorectal cancer screening: a cluster randomized trial design.

Chinese Americans underutilize colorectal cancer screening. This study evaluated a physician-based intervention guided by social cognitive theory (SCT) to inform future research involving minority physicians and patients. Twenty-five Chinese-speaking primary care physicians were randomized into intervention or usual care arms. The intervention included two 45-minute in-office training sessions paired with a dual-language communication guide detailing strategies in addressing Chinese patients' screening barriers. Physicians' feedback on the intervention, their performance data during training, and pre-post intervention survey data were collected and analyzed. Most physicians (~85%) liked the intervention materials but ~84% spent less than 20 minutes reading the guide and only 46% found the length of time for in-office training acceptable. Despite this, the intervention increased physicians' perceived communication self-efficacy with patients (p<.01). This study demonstrated the feasibility of enrolling and intervening with minority physicians. Time constraints in primary care practice should be considered in the design and implementation of interventions.

The 6-MP versus placebo clinical trial in acute leukemia.

BACKGROUND: This article gives the status of clinical cancer research in the 1950's-1960's and tells the story of the development and conduct of the 6-mercaptopurine (6-MP) versus placebo clinical trial in acute leukemia through the initiation, design, conduct and analysis stages, with emphasis on the ethical aspects of randomizing patients to 6-MP or placebo when in remission. PURPOSE: The specific objective was to compare the lengths of remission for patients receiving 6-MP or placebo after achieving complete or partial remission from steroid treatment. METHODS: A randomized, double-blind, placebo controlled sequential study was conducted in which patients were paired by remission status at each of the eleven institutions participating in the study, and randomized to 6-MP or placebo within each pair of patients. A preference for 6-MP or placebo was recorded depending on which patient in the pair had the longer remission. The preferences were plotted according to a restricted sequential procedure devised by Peter Armitage and, depending on which boundary of the design was crossed, a statistically significant difference could be declared favoring 6-MP, placebo or no preference. CONCLUSIONS: The trial established the efficacy of 6-MP for maintaining longer remissions in acute leukemia and led to the concept of 'adjuvant chemotherapy', namely that patients with minimal disease have a substantially better response to chemotherapy than patients with advanced disease, a concept that has been followed in many other forms of cancer. Statistically, the fact that many patients were still in remission when the study was stopped (i.e. the length of remission data for these patients was 'right censored') led to the development of a generalized Wilcoxon test and was an important influence on Cox's development of the proportional hazards model. The trial had an innovative design in the early 1960's and has been an important influence on subsequent clinical research in cancer and statistical research in survival analysis.

Treatment-subgroup interaction: an example from a published, phase II clinical trial.

Phase II trial designs that ignore between-patient heterogeneity and do not allow for treatment-subgroup interactions may produce very large false positive and false negative error rates if efficacy varies by subgroup. Recent discussions of this problem were illustrated with scenarios and computer simulations. In this short communication, we reanalyzed a published phase II trial to highlight the need to consider between-patient heterogeneity and the possibility of treatment-subgroup interaction when designing and analyzing phase II studies. The single-arm trial evaluated amsacrine plus cytosine arabinoside, vincristine, and prednisone (a combination abbreviated as OAP) for adult acute leukemia, when standard treatment was adriamycin plus OAP. We carried out an analysis of covariance (ANCOVA) incorporating data from historical control patients who met eligibility criteria for the trial and received standard treatment at the study center in the years immediately preceding the trial. Patients administered experimental treatment and control patients were classified as having favorable or unfavorable prognosis according to their predicted probability of response to standard treatment. When the prognostic subgroup of patients was ignored, the response rates for experimental and standard treatment appeared similar. However, fitting an ANCOVA model determined that the effects of subgroup, treatment, and their interaction were statistically significant: experimental treatment was superior to standard treatment in patients with unfavorable prognosis and inferior to standard treatment in patients with favorable prognosis. This real-world example of treatment-subgroup interaction highlights the need to employ phase II designs that consider between-patient heterogeneity and the possibility that efficacy differs by subgroup.

The properties of high-dimensional data spaces: implications for exploring gene and protein expression data.

High-throughput genomic and proteomic technologies are widely used in cancer research to build better predictive models of diagnosis, prognosis and therapy, to identify and characterize key signalling networks and to find new targets for drug development. These technologies present investigators with the task of extracting meaningful statistical and biological information from high-dimensional data spaces, wherein each sample is defined by hundreds or thousands of measurements, usually concurrently obtained. The properties of high dimensionality are often poorly understood or overlooked in data modelling and analysis. From the perspective of translational science, this Review discusses the properties of high-dimensional data spaces that arise in genomic and proteomic studies and the challenges they can pose for data analysis and interpretation.

Cyberknife radiosurgery for breast cancer spine metastases: a matched-pair analysis.

BACKGROUND: There are few options for breast cancer patients with spinal metastases recurrent within a previous radiation treatment field. CyberKnife radiosurgery has been used in our institution to treat such patients. To evaluate their outcomes, as there are no comparable radiation treatment options, the outcomes were compared between 18 patients with spinal metastases from breast cancer treated with CyberKnife stereotactic radiosurgery, 17 of which had prior radiotherapy to the involved spinal region and were progressing, and 18 matched patients who received conventional external beam radiotherapy (CRT) up-front for spinal metastases. METHODS: Radiosurgery was delivered in 3 to 5 fractions to doses ranging from 2100 to 2800 cGy. Women were matched to patients in a CRT group with respect to time from original diagnosis to diagnosis of metastases, estrogen receptor / progesterone receptor (ER/PR) status, presence or absence of visceral metastases, prior radiotherapy, and prior chemotherapy. Survival and complications were compared between treatment groups. Surviving patients were followed out to 24 months. RESULTS: The CyberKnife and CRT groups were comparable along all matching dimensions and in performance status before treatment. Outcomes of treatment were similar for patients in both groups; ambulation, performance status, and pain worsened similarly across groups posttreatment. Survival and the number of complications appeared to favor the CyberKnife group, but the differences did not reach statistical significance. CONCLUSIONS: The statistical comparability of the CyberKnife and CRT groups reflects the small sample size and stringent requirements for significance of the matched-pair analysis. Nevertheless, comparability in these difficult cases shows that salvage CyberKnife treatment is as efficacious as initial CRT without added toxicity.

The development of novel agents for the treatment of colorectal cancer: a critical review of current practice and some suggestions for the future.

The pathways to approval of new therapeutic agents in the United States and globally rely on the performance of well-designed clinical trials demonstrating both safety and efficacy. We recognize that the last decade has seen some great successes in improving outcomes for patients with cancer and, specifically, for patients with colorectal cancer. The development of novel agents active in colon cancer has led to improved survival and cure rates. However, because of the number of agents now available and the established practice patterns, it is becoming increasingly difficult to test new agents in cancer, particularly in colorectal cancer. The focus of this article is to review the current clinical trial designs with a critical eye and propose novel approaches to bringing new agents into the armamentarium of agents effective against colorectal cancer. Our current standards for drug development are increasingly problematic, and it is imperative that we develop new expectations and supporting standards in cancer drug development.

Paroxetine is an effective treatment for hot flashes: results from a prospective randomized clinical trial.

PURPOSE: In an open-label trial we have previously demonstrated that paroxetine reduces hot flashes. We initiated a stratified, randomized, double-blind, cross-over, placebo-controlled trial to investigate the efficacy of paroxetine 10 mg and 20 mg compared to placebo in reducing hot flash frequency and composite score. A secondary objective was to evaluate quality of life (QOL) parameters. PATIENTS AND METHODS: Women who suffered at least two hot flashes a day for 1 month or longer were eligible. Women were randomly assigned to 4 weeks of paroxetine 10 mg or 20 mg followed by placebo for 4 weeks, or placebo for 4 weeks followed by paroxetine 10 mg or 20 mg for 4 weeks. Participants completed baseline daily hot flash diaries for one week prior to the start of the study and throughout the study, and QOL questionnaires at baseline, week 5 and week 9. RESULTS: 279 women were screened, and 151 were randomly assigned. Paroxetine 10 mg reduced hot flash frequency and composite score by 40.6% and 45.6%, respectively, compared to 13.7% and 13.7% for placebo (P = .0006 and P = .0008, respectively). Paroxetine 20 mg reduced hot flash frequency and composite score by 51.7% and 56.1%, respectively, compared with 26.6% and 28.8% for placebo (P = .002 and P = .004, respectively). Efficacy was similar between the two doses, but women were less likely to discontinue low-dose paroxetine. Paroxetine 10 mg was associated with a significant improvement in sleep compared with placebo (P = .01). CONCLUSION: Paroxetine is an effective treatment for hot flashes in women with or without a prior breast cancer.

A multicenter randomized clinical trial evaluating interleukin-2 activated hematopoietic stem cell transplantation and post-transplant IL-2 for high risk breast cancer patients.

PURPOSE: This Phase III randomized multicenter trial compared progression-free (PFS) and overall survival (OS) for autologous peripheral blood stem cell (aPBSC) transplantation with or without immunotherapy in high-risk breast cancer patients. METHODS: Eligible patients had American Joint Committee on Cancer (AJCC) 5th Edition Stage II/IIIA with > or = 4 axillary nodes, Stage IIIB, or chemotherapy-sensitive or stable Stage IV disease. Following treatment with cyclophosphamide, thiotepa and carboplatin (STAMP V), patients were randomized to aPBSC transplant with or without immunotherapy. Patients on immunotherapy received cells that were incubated in interleukin-2 (IL-2) for 24 h followed by parenteral IL-2 for 5 days then 2 days of rest for 4 weeks. RESULTS: Fifty-nine patients were treated (35 Stage II/IIIA; 13 Stage IIIB; 11 Stage IV), 30 patients were randomized to immunotherapy and 29 patients to no immunotherapy. Neutrophils engrafted a median of 10 days post-transplant in both groups. The median times to platelet engraftment were 9 and 10 days after transplant in the no-immunotherapy and immunotherapy groups, respectively (p = 0.03). There was no statistical evidence (p = 0.61) of a difference in progression-free and surviving (PFS) at 3 years for patients receiving immunotherapy (53%) compared with no immunotherapy (48%). There was some evidence of superiority in overall survival (OS) at 3 years for patients receiving immunotherapy (83%) compared with no immunotherapy (69%), but the difference between survival curves was not statistically significant (p = 0.08). Also, there was some evidence that patients developing acute graft versus host disease (aGVHD) had superior PFS (p = 0.02) but not OS (p = 0.19) than patients not developing aGVHD. Toxicities were transient and similar between groups, with no treatment-related deaths. CONCLUSIONS: This phase III study of high-risk breast cancer patients randomized to immunotherapy or no immunotherapy demonstrated that a well-tolerated immunotherapy regimen added to aPBSC transplant did not improve PFS, but there was some improvement in OS, but not by an amount that was statistically significant (p = 0.08).

Activation of signal transducer and activator of transcription-5 in prostate cancer predicts early recurrence.

PURPOSE: We have shown previously that the signal transducer and activator of transcription-5 (Stat5) is a critical survival factor in human prostate cancer cells. In addition, we recently showed that Stat5 is activated at a high level, particularly in high-grade human prostate cancers. Here, we investigated whether activation of Stat5 in prostate cancer was linked to clinical outcome with disease recurrence as end point. EXPERIMENTAL DESIGN: Immunohistochemistry was used to detect active, nuclear Stat5 in 357 paraffin-embedded prostate cancer specimens on a tissue microarray with clinical follow-up data. Stat5 activation status in prostate cancer specimens was analyzed by univariate and multivariate survival analysis to determine whether activation of Stat5 predicts earlier prostate cancer recurrence. Separate sets of statistical analysis were done for all patients regardless of Gleason grade and for patients with prostate cancer of intermediate Gleason grades (3 and 4). RESULTS AND CONCLUSIONS: Stat5 activation in prostate cancer was associated with early disease recurrence (P = 0.0399). Importantly, active Stat5 also predicted shorter progression-free survival in intermediate Gleason grade prostate cancers (P = 0.0409). Stat5 activation remained an independent prognostic marker after adjusting for Gleason grade, pT stage, perineural invasion, or seminal vesicle infiltration in all patients (P = 0.0565) and in Gleason grade 3 or 4 patients (P = 0.0582). The results of this work also confirmed our previous finding of association of Stat5 activation with a high histologic grade of prostate cancer (R = 0.11, P = 0.033). In summary, our study shows that active Stat5 distinguished prostate cancer patients whose disease is likely to progress earlier; therefore, active Stat5 may be a useful marker for selection of more individualized treatment. The results of this study need to be validated in a large prospective cohort.

Gene selection for microarray data analysis using principal component analysis.

Principal component analysis (PCA) has been widely used in multivariate data analysis to reduce the dimensionality of the data in order to simplify subsequent analysis and allow for summarization of the data in a parsimonious manner. It has become a useful tool in microarray data analysis. For a typical microarray data set, it is often difficult to compare the overall gene expression difference between observations from different groups or conduct the classification based on a very large number of genes. In this paper, we propose a gene selection method based on the strategy proposed by Krzanowski. We demonstrate the effectiveness of this procedure using a cancer gene expression data set and compare it with several other gene selection strategies. It turns out that the proposed method selects the best gene subset for preserving the original data structure.

Supplementary analysis of probabilities at the termination of a group sequential phase II trial.

We consider estimation of various probabilities after termination of a group sequential phase II trial. A motivating example is that the stopping rule of a phase II oncologic trial is determined solely based on response to a drug treatment, and at the end of the trial estimating the rate of toxicity and response is desirable. The conventional maximum likelihood estimator (sample proportion) of a probability is shown to be biased, and two alternative estimators are proposed to correct for bias, a bias-reduced estimator obtained by using Whitehead's bias-adjusted approach, and an unbiased estimator from the Rao-Blackwell method of conditioning. All three estimation procedures are shown to have certain invariance property in bias. Moreover, estimators of a probability and their bias and precision can be evaluated through the observed response rate and the stage at which the trial stops, thus avoiding extensive computation.

The nuclear receptor coactivator AIB1 mediates insulin-like growth factor I-induced phenotypic changes in human breast cancer cells.

The nuclear receptor coactivator AIB1 (amplified in breast cancer 1) is overexpressed in human breast cancers and is required for estrogen signaling. However, the role of AIB1 in breast cancer etiology is not known. Here, we show that AIB1 is rate-limiting for insulin-like growth factor I (IGF-I)-dependent phenotypic changes and gene expression in human breast cancer cells. Reduction of endogenous AIB1 levels by small interfering RNA in MCF-7 breast cancer cells prevented IGF-I-stimulated anchorage-independent growth by reducing IGF-I-dependent anti-anoikis. cDNA array and immunoblot analysis of gene expression revealed that reduction in AIB1 levels led to a significant decrease in the expression of several genes controlling the cell cycle and apoptosis. These AIB1-dependent changes were also observed in the presence of estrogen antagonist and were corroborated in the estrogen receptor-negative cell line MDA MB-231. AIB1 reduction decreased the expression of the IGF-I receptor and IRS-1 in MCF-7 but not in MDA MB-231 cells. IGF-I-stimulated activation of AKT was reduced by AIB1 small interfering RNA treatment, whereas mitogen-activated protein kinase (extracellular signal-regulated kinase 1/2) activation by IGF-I was unaffected. We conclude that AIB1 is required for IGF-I-induced proliferation, signaling, cell survival, and gene expression in human breast cancer cells, independent of its role in estrogen receptor signaling.

Progressive loss of Syk and abnormal proliferation in breast cancer cells.

The tumor suppressor gene Syk tyrosine kinase is absent or reduced in invasive breast cancer tissues and cell lines; its loss in breast tissues is linked to poor prognosis and metastasis. Also, evidence shows that in vitro Syk is involved in regulating proliferation. Here, we show by in situ hybridization on breast tissue sections that the loss of Syk expression is progressive during tumor development. Strikingly, Syk is already partially lost in normal epithelial tissue adjacent to the cancer lesion. In vivo, cell proliferation (as measured by the proliferative index Ki67) increased from normal to ductal carcinoma in situ to invasive, whereas Syk in situ staining in the same tissues decreased. In vitro, the presence of Syk was associated with reduced cell proliferation in an epidermal growth factor receptor-overexpressing breast cancer cell line, BT549, whereas changes in apoptosis were undetected. Concomitantly, the kinase activity of the proto-oncogene Src was reduced by approximately 30%. A 5-fold increase in abnormal mitoses was observed in the Syk-transfected cells compared with vector control. We propose that Syk is involved in the regulation of cell proliferation, possibly by controlling mechanisms of mitosis and cytokinesis via Src signal transduction pathway(s). Because of its progressive and early loss during tumor onset and development, monitoring of Syk loss in breast epithelial cells by noninvasive techniques such as ductal lavage may be a powerful tool for screening purposes.

SCC-112, a novel cell cycle-regulated molecule, exhibits reduced expression in human renal carcinomas.

We report here the identification and an initial characterization of a novel cell cycle-regulated molecule, SCC-112. SCC-112 cDNA (6744 bp) encodes a longest open reading frame (ORF) comprised of 1297 amino acids, representing a approximately 150-kDa nuclear protein. SCC-112 mRNA and protein levels were relatively high during the G2/M phase of the cell cycle in MDA-MB 435 breast cancer cells. Transient expression of SCC-112 cDNA in COS-1 cells led to an increase in the number of cells in sub-G1 phase and enhanced activity of caspase-3, a downstream effector of apoptosis. Stable transfection of SCC-112 cDNA in MDA-MB 231 breast cancer cells also led to an increase in the number of cells in sub-G1 phase ( approximately 2-3-fold), indicative of apoptosis. The examination of the paired sets of human normal and tumor tissues revealed that the SCC-112 mRNA level was significantly high in normal breast and kidney tissues as compared to the corresponding primary tumor tissues (P<0.0001; breast, n=50, and kidney, n=20). Consistent with these observations, SCC-112 protein expression (150 kDa) was high in a majority of the normal renal tissues examined as compared to the matched renal tumor tissues (67%, 1.2-fold to>10-fold, n=18). Taken together, these findings suggest that the SCC-112 gene expression is likely to be associated with normal cell growth and proliferation.

Long-term outcomes after radical prostatectomy performed in a community-based health maintenance organization.

BACKGROUND: Radical prostatectomy is used widely for the treatment of patients with localized prostate carcinoma. No long-term analysis has been reported on a series of radical prostatectomies performed in a community-based health maintenance organization. METHODS: Charts and histologic slides were reviewed from 750 patients who underwent radical prostatectomy between 1970 and 1996 at a community-based health maintenance organization. The influences of a number of variables were analyzed for their impact on progression free survival (PFS) and overall survival (OS). RESULTS: With a median follow-up of 6.2 years among survivors, 137 patients (18%) had progressive disease, and 149 patients (20%) died from all causes. The median OS from the date of diagnosis was 15.7 years (95% confidence interval, 13.6-17.2), similar to the expected median survival of 16.2 years. The median PFS from diagnosis was not reached, but 75% of patients were progression free > or = 10.6 years after undergoing prostatectomy. The prognostic factors included Gleason score, age at diagnosis, and T stage. Outcomes were comparable with reports of surgical series from university-based practices. CONCLUSIONS: The patient characteristics that had important, favorable correlation with survival included Gleason score < or = 6, T1 or T2 tumor status, and younger age at diagnosis. Lower prostate-specific antigen values at diagnosis, together with the former two parameters, also had a favorable correlation with PFS. Radical prostatectomy in a community-based health maintenance organization was followed by long-term PFS and OS comparable to outcomes reported from university-based practices. The impact of radical prostatectomy on survival remains to be demonstrated.

Stat5a is tyrosine phosphorylated and nuclear localized in a high proportion of human breast cancers.

Signal transducers and activators of transcription (STATs) are latent cytoplasmic transcription factors that are activated and translocated into the nucleus after phosphorylation at a conserved tyrosine residue. Mouse model studies have demonstrated that activated Stat5a acts as a critical survival factor for normal, preneoplastic and malignant mammary epithelial cells. Very limited information is available, however, on the expression, tyrosine phosphorylation status and nuclear localization of Stat5a in human breast cancers. In our study, the pattern of Stat5a cellular localization was analyzed by immunohistochemistry in a series of 83 randomly selected primary human breast adenocarcinomas. Immunoprecipitation/Western blotting and immunohistochemistry assays employing different phospho-specific antibodies verified Stat5a tyrosine phosphorylation status. Stat5a was nuclear localized and tyrosine phosphorylated in 59 of 78 (76%) breast cancers examined; 38 of 78 (49%) demonstrated Stat5a nuclear localization in more than 25% of the breast cancer cells within the adenocarcinomas. Nuclear localized Stat5a was associated positively with increased levels of histologic differentiation (p = 0.03). A statistically significant positive association with p27 nuclear localization also was identified (p = 0.05). No relationship was found between nuclear localized Stat5a and menopausal status, tumor size, ploidy, percentage of cells in S-phase, lymph node metastases, ER, ErbB2, nuclear localized p21 or nuclear localized Stat5b/Stat3. As its role in human breast cancer progression and response to therapy is defined, Stat5a could become a new molecular target for breast cancer therapy.

Block principal component analysis with application to gene microarray data classification.

We propose a block principal component analysis method for extracting information from a database with a large number of variables and a relatively small number of subjects, such as a microarray gene expression database. This new procedure has the advantage of computational simplicity, and theory and numerical results demonstrate it to be as efficient as the ordinary principal component analysis when used for dimension reduction, variable selection and data visualization and classification. The method is illustrated with the well-known National Cancer Institute database of 60 human cancer cell lines data (NCI60) of gene microarray expressions, in the context of classification of cancer cell lines.

Mobilization of peripheral blood stem cells with paclitaxel and rhG-CSF in high-risk breast cancer patients.

Preclinical studies have demonstrated the rapid and efficient mobilization of hematopoietic peripheral blood stem cells (PBSC) in a mouse model using the combination of paclitaxel with recombinant human granulocyte colony-stimulating factor (rhG-CSF). On the basis of these results, a clinical trial was initiated using rhG-CSF with paclitaxel for PBSC mobilization in high-risk breast cancer patients. The mobilized PBSC were evaluated for CD34(+) cell number, mononuclear cell content, and clonogenic potential. One-hundred and seventeen breast cancer patients received paclitaxel (300 mg/m(2)) administered as a 24-h continuous intravenous infusion. Forty-eight hours after completing paclitaxel, rhG-CSF (5 microg/kg) was initiated and continued until completion of PBSC collection. Leukapheresis was initiated once the white blood cell count reached 1.0 x 10(9)/L. Each collection was evaluated for the numbers of mononuclear cells (MNC) and CD34(+) cells. Clonogenic potential was enumerated using colony-forming units-granulocyte-macrophage (CFU-GM) and burst-forming units-erythroid (BFU-E). Patients receiving paclitaxel with rhG-CSF mobilized a large number of mononuclear cells/apheresis (mean, 3.7 x 10(8); range, 3.3-4.1) and CD34(+) cells/apheresis (mean, 7.2 x 10(6); range, 6.1-8.4). The average number of leukophereses needed was 1.8 (mean, range 1.6-2.0). Colony growth was normal with 178.9 x 10(5) and 214.8 x 10(5) colonies counted in CFU-GM and BFU-E assays, respectively. Patients engrafted platelets and neutrophils on day 10 following transplantation. In conclusion, PBSC mobilization with paclitaxel and rhG-CSF results in a large number of mononuclear cells and CD34(+) cells with normal clonogenic potential. The cells engraft normally following high-dose chemotherapy and autologous stem cell transplantation in high-risk breast cancer patients. These results demonstrate that paclitaxel with rhG-CSF is an efficient mobilizing agent in high-risk breast cancer patients.