Darbepoetin-alfa and intravenous iron administration after autologous hematopoietic stem cell transplantation: a prospective multicenter randomized trial.

We conducted a randomized study analyzing the impact of darbepoetin alfa (DA) administration with or without intravenous (i.v.) iron on erythroid recovery after autologous hematopoietic cell transplantation (HCT). Patients were randomized between no DA (Arm 1), DA 300 µg every 2 weeks starting on Day 28 after HCT (Arm 2), or DA plus i.v. iron 200 mg on Days 28, 42, and 56 (Arm 3). The proportion achieving complete hemoglobin (Hb) response within 18 weeks (primary end point) was 21% in Arm 1 (n = 24), 79% in Arm 2 (n = 25), and 100% in Arm 3 (n = 23; P < 0.0001). Erythropoietic response was shown to be significantly higher in Arm 3 (n = 46) than in Arm 2 (n = 50; P = 0.008), resulting in lower DA use, reduced drug costs, and improved quality of life scores, but the effect on transfusions was not significant. In multivariate analysis, DA administration (P < 0.0001), i.v. iron administration (P = 0.0010), high baseline Hb (P < 0.0001), and low baseline creatinine (P = 0.0458) were independently associated with faster achievement of complete Hb response. In conclusion, DA is highly effective to ensure full erythroid reconstitution after autologous HCT when started on Day 28 post-transplant. I.v. iron sucrose further improves erythroid recovery.

Cotransplantation of mesenchymal stem cells might prevent death from graft-versus-host disease (GVHD) without abrogating graft-versus-tumor effects after HLA-mismatched allogeneic transplantation following nonmyeloablative conditioning.

Recent studies have suggested that coinfusion of mesenchymal stem cells (MSCs) the day of hematopoietic cell transplantation (HCT) might promote engraftment and prevent graft-versus-host disease (GVHD) after myeloablative allogeneic HCT. This prompted us to investigate in a pilot study whether MSC infusion before HCT could allow nonmyeloablative (NMA) HCT (a transplant strategy based nearly exclusively on graft-versus-tumor effects for tumor eradication) from HLA-mismatched donors to be performed safely. Twenty patients with hematologic malignancies were given MSCs from third party unrelated donors 30-120 minutes before peripheral blood stem cells (PBSCs) from HLA-mismatched unrelated donors, after conditioning with 2 Gy total body irradiation (TBI) and fludarabine. The primary endpoint was safety, defined as a 100-day incidence of nonrelapse mortality (NRM) <35%. One patient had primary graft rejection, whereas the remaining 19 patients had sustained engraftment. The 100-day cumulative incidence of grade II-IV acute GVHD (aGVHD) was 35%, whereas 65% of the patients experienced moderate/severe chronic GVHD (cGVHD). One-year NRM (10%), relapse (30%), overall survival (OS) (80%) and progression-free survival (PFS) (60%), and 1-year incidence of death from GVHD or infection with GVHD (10%) were encouraging. These figures compare favorably with those observed in a historic group of 16 patients given HLA-mismatched PBSCs (but no MSCs) after NMA conditioning, which had a 1-year incidence of NRM of 37% (P = .02), a 1-year incidence of relapse of 25% (NS), a 1-year OS and PFS of 44% (P = .02), and 38% (P = .1), respectively, and a 1-year rate of death from GVHD or infection with GVHD of 31% (P = .04). In conclusion, our data suggest that HLA-mismatched NMA HCT with MSC coinfusion appeared to be safe.

Dexamethasone compared to prednisolone for adults with acute lymphoblastic leukemia or lymphoblastic lymphoma: final results of the ALL-4 randomized, phase III trial of the EORTC Leukemia Group.

BACKGROUND: Corticosteroids are a standard component of the treatment of acute lymphoblastic leukemia and lymphoblastic lymphoma. Our aim was to determine whether dexamethasone results in a better outcome than prednisolone. DESIGN AND METHODS: Adult patients with acute lymphoblastic leukemia or lymphoblastic lymphoma were randomized to receive, as part of their induction therapy on days 1-8 and 15-22, either dexamethasone 8 mg/m(2) or prednisolone 60 mg/m(2). Those who reached complete remission were given two courses of consolidation therapy with high-dose cytarabine and mitoxantrone and methotrexate and asparaginase. Subsequently patients younger than 50 years, with a suitable donor, were to undergo allogeneic stem cell transplantation, whereas the others were planned to receive either an autologous stem cell transplant or high-dose maintenance chemotherapy with prophylactic central nervous system irradiation. Randomization was done with a minimization technique. The primary endpoint was event-free survival and the analyses was conducted on an intention-to-treat basis. RESULTS: Between August 1995 and October 2003, 325 patients between 15 to 72 years of age were randomized to receive either dexamethasone (163 patients) or prednisolone (162 patients). After induction and the course of first consolidation therapy, 131 (80.4%) patients in the dexamethasone group and 124 (76.5%) in the prednisolone group achieved complete remission. No significant difference was observed between the two treatment groups with regards to 6-year event-free survival rates (+/-SE) which were 25.9% (3.6%) and 28.7% (3.5%) in the dexamethasone and prednisolone groups, respectively (P=0.82, hazard ratio 0.97; 95% confidence interval, 0.75-1.25). Disease-free survival after complete remission was also similar in the dexamethasone and prednisolone groups, the 6-year rates being 32.3% and 37.5%, respectively (hazard ratio 1.03; 95% confidence interval 0.76-1.40). The 6-year cumulative incidences of relapse were 49.8% and 53.5% (Gray's test: P=0.30) while the 6-year cumulative incidences of death were 18% and 9% (Gray's test: P=0.07). CONCLUSIONS: In the ALL-4 trial in adult patients with acute lymphoblastic leukemia or lymphoblastic lymphoma, treatment with dexamethasone did not show any advantage over treatment with prednisolone.

Recombinant human erythropoietin therapy after allogeneic hematopoietic cell transplantation with a nonmyeloablative conditioning regimen: low donor chimerism predicts for poor response.

PURPOSE: After allogeneic hematopoietic stem cell transplantation with nonmyeloablative conditioning (NMHCT), many patients experience prolonged anemia and require red blood cell (RBC) transfusions. We enrolled 60 consecutive patients undergoing NMHCT in a phase II trial to determine the optimal utilization of recombinant human erythropoietin (rHuEPO) therapy in this setting. PATIENTS AND METHODS: The first 14 NMHCT recipients did not receive rHuEPO (control group). Nineteen patients were scheduled to start rHuEPO on day 0 (EPO group 2) and 27 patients on day 28 after the transplant (EPO group 1). RHuEPO was administered subcutaneously once weekly at a dose of 500 U/kg/wk with the aim of achieving hemoglobin (Hb) levels of 13 g/dL. The 3 groups were well balanced for major characteristics. RESULTS: During the first month (p < 0.0001) as well as days 30 to 100 (p < 0.0001) and days 100 to 180 (p < 0.0001), Hb values were higher in patients receiving rHuEPO compared to those not receiving it. However, transfusion requirements were significantly decreased only in the first month in EPO group 2 (p = 0.0169). T-cell chimerism above 60% on day 42 was the best predictor of Hb response (p < 0.0001) or Hb correction (p = 0.0217), but myeloid chimerism above 90% also predicted for Hb response (p = 0.0069). Hb response was also decreased in patients receiving CD8-depleted grafts and increased in the few patients not receiving TBI, but only in univariate analysis. CONCLUSIONS: Anemia after NMHCT is sensitive to rHuEPO therapy, but less so than after conventional allogeneic HCT. RHuEPO decreases transfusion requirements only in the first 30 days posttransplant. T-cell chimerism below 60% on day 42 impaired Hb response, suggesting possible inhibition of donor erythropoiesis by residual recipient lymphocytes. A prospective randomized trial should be performed with rHuEPO starting on the day of transplantation to assess its clinical benefit in terms of transfusion requirements and quality of life.

Pegfilgrastim compared with Filgrastim after autologous hematopoietic peripheral blood stem cell transplantation.

In order to assess the effect of Pegfilgrastim on the duration of neutropenia and clinical outcome of patients after autologous peripheral blood stem cell (PBSC) transplantation, we compared 20 consecutive patients with lymphoma or multiple myeloma receiving a single 6-mg dose of Pegfilgrastim on day 1 posttransplant to an historical control group of 60 patients receiving daily Filgrastim 5 microg/kg starting on day 1 posttransplant. The duration of neutropenia was similar in the Pegfilgrastim group compared with the control group. There were no differences in time to neutrophil, erythroid, or platelet engraftment nor in the incidence of fever and infections. The duration of antibiotic therapy, transfusion support, and time to hospital discharge were similar in the two groups. However, after initial hematopoietic reconstitution, we observed significantly higher values of lymphocytes (e.g., 1,660+/-1,000 versus 970+/-460 on day 80, p=0.0002), neutrophils (e.g., 3,880+/-2,030 versus 2,420+/-1,500 on day 25, p=0.0004), reticulocytes (e.g., 148,160+/-90,590 versus 87,140+/-65,920 on day 25, p<0.0001), and platelets (e.g., 210,700+/-116,090 versus 150,240+/-58,230 on day 55, p=0.0052) up to day 100 in the Pegfilgrastim group compared with the Filgrastim group. These observations had no impact on clinical outcome of the patients after day 30 due to the low incidence of infectious events after engraftment in autologous PBSC transplantation. We conclude that the effect of Pegfilgrastim administrated on day 1 posttransplant is comparable to that of daily Filgrastim on initial hematopoietic reconstitution. The possibly superior effect of Pegfilgrastim on cell counts we observed after initial engraftment should be further tested in a prospective randomized trial.

Shortened first-line high-dose chemotherapy for patients with poor-prognosis aggressive lymphoma.

PURPOSE: Randomized trial LNH93-3 was conducted on patients who had poor-prognosis aggressive lymphoma and were younger than 60 years with two to three factors of the age-adjusted International Prognostic Index to evaluate the benefit of early high-dose therapy (HDT) with autologous stem-cell transplantation (ASCT). PATIENTS AND METHODS: Patients were randomized between doxorubicin, cyclophosphamide, vindesine, bleomycin, and prednisone (ACVBP) chemotherapy followed by sequential consolidation and an experimental shortened treatment consisting of three cycles with escalated doses of cyclophosphamide, epirubicin, vindesine, bleomycin, and prednisone and collection of peripheral-blood stem cells. On day 60, HDT was administered with 1,3-bis(2-chloroethyl)-1-nitrosourea, etoposide, cytarabine, and melphalan followed by ASCT. RESULTS: Eligible patients (n = 370) with aggressive lymphoma were analyzed. For ACVBP (181 patients) and HDT (189 patients), respective complete remission rates were 64% and 63%. With a median follow-up of 60 months, 5-year overall survival and event-free survival for ACVBP and HDT were 60% +/- 8% and 46% +/- 8% (P =.007) and 52 +/- 8% and 39 +/- 8% (P =.01), respectively. Survival was independently affected by age greater than 40 years (P =.0003), T-cell phenotype (P =.009), bone marrow involvement (P =.003), and HDT treatment group (P =.04). CONCLUSION: Early HDT with ASCT in high-risk patients was inferior to the ACVBP chemotherapy regimen. These results indicate that the received dose-intensity before HDT was too low when compared with ACVBP and HDT and was given too early.

Evaluation of therapy for lymphoma.

Positron emission tomography (PET) using (18)F-fluorodeoxyglucose ((18)F-FDG) is the best noninvasive imaging technique for to assess response in patients suffering from lymphoma. Early response evaluation ("interim PET") after one, a few cycles, or at midtreatment can predict response, progression-free survival, and overall survival. We calculated from data of 7 studies an overall sensitivity to predict treatment failure of 79%, a specificity of 92%, a positive predictive value (PPV) of 90%, a negative predictive value (NPV) of 81%, and an accuracy of 85%. Although it is not yet indicated to change patient management based on residual (18)F-FDG uptake on interim scan in chemotherapy-sensitive patients, prospective studies evaluating the role of an interim PET in patient management clearly are warranted. (18)F-FDG PET also has an important prognostic role in relapsing patients after reinduction chemotherapy before high-dose chemotherapy (HCT) followed by autologous stem cell transplantation (ASCT). However, all chemotherapy-sensitive patients remain candidates for HCT followed by ASCT, even if (18)F-FDG PET showed residual (18)F-FDG uptake. We calculated from data of 3 studies an overestimated risk of relapse in 16% of all PET-positive patients. Some patients with residual (18)F-FDG uptake will have a good outcome after HCT followed by ASCT. (18)F-FDG PET is the imaging technique of choice for end-of-treatment evaluation. However, (18)F-FDG is not specific for tumoral tissue. Active inflammatory lesions and infectious processes can be falsely interpreted as malignant residual cells. However, a negative (18)F-FDG PET cannot exclude minimal residual disease. Consequently, it is always indicated to correlate PET findings with clinical data, other imaging modalities, and/or a biopsy. We calculated, from data of 17 studies in end-of-treatment evaluation, a sensitivity of 76%, a specificity of 94%, a PPV of 82%, a NPV 92%, and an accuracy of 89%.

Efficacy of recombinant human erythropoietin therapy started one month after autologous peripheral blood stem cell transplantation.

On day 30 after autologous peripheral blood stem cell transplantation (PBSCT), 20 patients were randomized to receive either erythropoietin at a dose of 500 U/kg/week s.c. (Epo group) or no treatment (control group). After 3 weeks, hemoglobin (p<0.0001) and serum transferrin receptor (p<0.0001) concentrations were higher in the Epo group. Hb response (+2 g/dL) was achieved in 100% vs 28% (p<0.0001) and Hb correction (> or =13 g/dL) in 70% vs 10% (p=0.0238) of the patients, respectively. This is the first randomized study showing an efficacy of erythropoietin therapy on Hb levels after autologous PBSCT.

Recombinant human erythropoietin therapy is very effective after an autologous peripheral blood stem cell transplant when started soon after engraftment.

PURPOSE: Previous trials of recombinant human erythropoietin (rHuEpo) therapy after autologous hematopoietic stem cell transplantation have administered very high doses of i.v. rHuEpo starting on day 1 and continuing for 1-2 months until erythroid engraftment and have shown no benefit of rHuEpo therapy. We sought to establish a more effective use of rHuEpo in this setting. EXPERIMENTAL DESIGN: In this report, we show in a first cohort of 45 lymphoma or myeloma patients undergoing peripheral blood stem cell transplant (control group) that endogenous erythropoietin levels are high for the degree of anemia during the first 3 weeks after transplant but become adequate or slightly decreased thereafter. We thus enrolled 41 consecutive similar patients in a trial of rHuEpo therapy at a dose of 500 units/kg/week started on day 30 after the transplant. RESULTS: The 12-week probability of achieving hemoglobin (Hb) levels of 13 g/dl was 87% in rHuEpo-treated patients versus 14% in controls (P = 0.0001). Mean Hb levels were significantly higher in the rHuEpo group than in the control group from day 42 through day 150 after transplant (Ps of <0.05 to <0.001). Two of 41 patients in the rHuEpo group versus 12 of 45 patients in the control group had Hb levels of <9 g/dl between day 42 and day 100 after the transplant (P = 0.0078). CONCLUSIONS: Anemia after autologous peripheral blood stem cell transplant is exquisitely sensitive to rHuEpo when therapy is started soon after engraftment. This is the first convincing report showing that rHuEpo is effective in this setting. Our data set the stage for a more rational use of rHuEpo after autologous hematopoietic stem cell transplantation and should renew interest in erythropoietin therapy in this setting. Prospective, randomized trials should investigate the impact of rHuEpo therapy on transfusion requirements and quality of life.

Optimization of recombinant human erythropoietin therapy after allogeneic hematopoietic stem cell transplantation.

OBJECTIVE: Allogeneic hematopoietic stem cell transplantation (HSCT) is associated with prolonged anemia caused by defective erythropoietin (Epo) production. We enrolled 34 recipients of an allogeneic HSCT in three consecutive trials to determine the optimal utilization of recombinant human erythropoietin (rhEpo) therapy in this setting. MATERIALS AND METHODS: In the first trial (n = 7), rhEpo 1400 U/kg/week was given from day 1 until a hemoglobin (Hb) level of 10 g/dL was achieved, for a maximum of 60 days. In the second trial, rhEpo 500 U/kg/week was given to achieve Hb levels of 13 to 14 g/dL in 13 anemic patients with fatigue 56 to 1440 days after transplant. In the third trial, rhEpo was scheduled to start on day 35 in 14 patients at a dose of 500 U/kg/week with the aim of achieving Hb levels of 13 to 14 g/dL. RESULTS: In trial 1, erythroid recovery to 1% reticulocytes and red blood cell transfusion independence were faster, but the number of transfusions was not reduced compared to 10 controls. Responses were brisk in trial 2, with transfusion independence achieved after a median of 1 week in 12 of 13 patients, and 2-g Hb increments or Hb values of 11, 12, and 13 g/dL after 6, 7, 10, and 10 weeks, respectively. Transfusions were significantly reduced in the first month of rhEpo therapy. In trial 3, transfusion independence was obtained after a median of 1 week in 13 of 14 patients, and 2-g Hb increments or Hb values of 11, 12, and 13 g/dL after 3, 4, 6, and 8 weeks, respectively. Transfusions rates were considerably reduced compared to the previous month in the same patients or compared to controls undergoing peripheral blood or marrow transplant without rhEpo. CONCLUSIONS: Anemia after allogeneic HSCT is exquisitely sensitive to rhEpo. The benefit is minimal when it is given early post-transplant, as used in all trials to date. However, the rate of major response is greater than 90% when rhEpo is started after day 35. These data provide the basis on which to conduct a prospective, randomized, placebo-controlled trial of rhEpo therapy after allogeneic HSCT.

T-cell reconstitution after unmanipulated, CD8-depleted or CD34-selected nonmyeloablative peripheral blood stem-cell transplantation.

BACKGROUND: We have previously shown that CD8 depletion or CD34 selection of peripheral blood stem cells (PBSC) reduced the incidence of acute graft-versus-host disease (GvHD) after nonmyeloablative stem-cell transplantation (NMSCT). In this study, we analyze the effect of CD8 depletion or CD34 selection of the graft on early T-cell reconstitution. METHODS: Nonmyeloablative conditioning regimen consisted in 2 Gy total-body irradiation (TBI) alone, 2 Gy TBI and fludarabine, or cyclophosphamide and fludarabine. Patients 1 to 18 received unmanipulated PBSC, patients 19 to 29 CD8-depleted PBSC, and patients 30 to 35 CD34-selected PBSC. RESULTS: T-cell counts, and particularly CD4+ and CD4CD45RA+ counts, remained low the first 6 months after nonmyeloablative stem-cell transplantation (NMSCT) in all patients. CD34 selection (P<0.0001) but not CD8 depletion of PBSC significantly decreased T-cell chimerism. Donor T-cell count was similar in unmanipulated compared with CD8-depleted PBSC recipients but was significantly lower in CD34-selected PBSC recipients (P=0.0012). T cells of recipient origin remained stable over time in unmanipulated and CD8-depleted PBSC patients but expanded in some CD34-selected PBSC recipients between day 28 and 100 after transplant. Moreover, whereas CD8 depletion only decreased CD8+ counts (P<0.047), CD34 selection reduced CD3+(P<0.001), CD8+(P<0.016), CD4+ (P<0.001), and CD4+CD45RA+ (P<0.001) cell counts. T-cell repertoire was restricted in all patients on day 100 after hematopoietic stem-cell transplantation but was even more limited after CD34 selection (P=0.002). CONCLUSIONS: Despite of the persistence of a significant number of T cells of recipient origin, T-cell counts were low the first 6 months after NMSCT. Moreover, contrary with CD8 depletion of the graft that only affects CD8+ lymphocyte counts, CD34 selection dramatically decreased both CD8 and CD4 counts.

CD34+ cell dose predicts costs after autologous peripheral blood stem cell transplantation for breast cancer.

We assessed the effect of CD34+ cell dose on costs in breast cancer patients undergoing autologous peripheral blood stem cell (PBSC) transplantation. Mean hospitalization costs were 26,992.9+/-9582.9 for patients receiving a CD34+ cell dose <5 x 10(6) cells/kg versus 22,339.4+/- 5471.1 for those receiving >5 x 10(6) CD34+ cells/kg (p=0.0065).

Allogeneic stem cell transplantation in acute lymphoblastic leukemia and non-Hodgkin's lymphoma for patients

BACKGROUND AND OBJECTIVES: In the EORTC ALL-3 trial, the efficacy of allogeneic transplantation was compared with that of autologous marrow transplantation and maintenance chemotherapy in patients

High-dose cytarabine in induction treatment improves the outcome of adult patients younger than age 46 years with acute myeloid leukemia: results of the EORTC-GIMEMA AML-12 trial.

PURPOSE: Cytarabine plays a pivotal role in the treatment of patients with acute myeloid leukemia (AML). Most centers use 7 to 10 days of cytarabine at a daily dose of 100 to 200 mg/m(2) for remission induction. Consensus has not been reached on the benefit of higher dosages of cytarabine. PATIENTS AND METHODS: The European Organisation for Research and Treatment of Cancer (EORTC) and Gruppo Italiano Malattie Ematologiche dell' Adulto (GIMEMA) Leukemia Groups conducted a randomized trial (AML-12; Combination Chemotherapy, Stem Cell Transplant and Interleukin-2 in Treating Patients With Acute Myeloid Leukemia) in 1,942 newly diagnosed patients with AML, age 15 to 60 years, comparing remission induction treatment containing daunorubicin, etoposide, and either standard-dose (SD) cytarabine (100 mg/m(2) per day by continuous infusion for 10 days) or high-dose (HD) cytarabine (3,000 mg/m(2) every 12 hours by 3-hour infusion on days 1, 3, 5, and 7). Patients in complete remission (CR) received a single consolidation cycle containing daunorubicin and intermediate-dose cytarabine (500 mg/m(2) every 12 hours for 6 days). Subsequently, a stem-cell transplantation was planned. The primary end point was survival. RESULTS: At a median follow-up of 6 years, overall survival was 38.7% for patients randomly assigned to SD cytarabine and 42.5% for those randomly assigned to HD cytarabine (log-rank test P = .06; multivariable analysis P = .009). For patients younger than age 46 years, survival was 43.3% and 51.9%, respectively (P = .009; multivariable analysis P = .003), and for patients age 46 to 60 years, survival was 33.9% and 32.9%, respectively (P = .91). CR rates were 72.0% and 78.7%, respectively (P < .001) and were 75.6% and 82.4% for patients younger than age 46 years (P = .01) and 68.3% and 74.8% for patients age 46 years and older (P = .03). Patients of all ages with very-bad-risk cytogenetic abnormalities and/or FLT3-ITD (internal tandem duplication) mutation, or with secondary AML benefitted from HD cytarabine. CONCLUSION: HD cytarabine produces higher remission and survival rates than SD cytarabine, especially in patients younger than age 46 years.

Selective defect of anti-pneumococcal IgG in a patient with persistent polyclonal B cell lymphocytosis.

BACKGROUND: Persistent polyclonal B cell lymphocytosis (PPBL) is a rare condition characterized by increased IgM and large excess of B cells with an IgD(+) CD27(+) phenotype. In normal individuals, these cells play a central role in the defense against pneumococcal infection. So far, few studies have characterized humoral immune responses in PPBL patients. We therefore measured IgG directed against S. pneumoniae antigens in a 51 yr-old woman with PPBL before and after vaccination with a pneumococcal 23-valent polysaccharide vaccine. METHODS: Antibodies against pneumococcal antigens were measured first with an overall immunoassay using microplates coated with the 23-valent pneumococcal vaccine. A serotype-specific test was also performed according to the WHO consensus protocol. RESULTS: Despite a large number of IgD(+) CD27(+) cells, our patient had low baseline titers of IgG directed against pneumococcal antigens and did not significantly respond to a 23-valent polysaccharide vaccine against S. pneumoniae. On the contrary, she had good titers of IgG directed against tetanus toxoid. CONCLUSION: IgM(+) IgD(+) CD27(+) cells which accumulate in this patient with typical PPBL patient failed to perform IgG isotype switch after a polysaccharide vaccine. The potential mechanisms and relationships with the main features of PPBL are discussed. Further studies on a larger number of similar patients are needed.

A randomized multicenter study of optimal circadian time of vinorelbine combined with chronomodulated 5-fluorouracil in pretreated metastatic breast cancer patients: EORTC trial 05971.

Studies in animals synchronized with an alternation of 12 h of light and 12 h of darkness have showed that hematological and systemic toxicities could be reduced if vinorelbine were administered 19 or 23 hours after light onset (HALO), corresponding to 17:00 and 21:00 h in diurnally active humans. This trial aimed to define the least toxic time of vinorelbine administration in metastatic breast cancer patients. Initially, the study treatment consisted of three courses of vinorelbine of 30 mg/m(2)/d on D1 and D6 and chronomodulated 5-fluorouracil of 850 mg/m(2) from D2 to D5 every 21 days. Ninety metastatic breast cancer patients were randomized to receive vinorelbine at one of the eight possible dosing times. Further to the recommendations of the Independent Data Monitoring Committee, the vinorelbine dose was reduced to 25 mg/m(2)/d midway through the study. The primary objective of the study was detection of the least toxic time based on the incidence of grade 3-4 (G3-4) neutropenia. To show a significant result, the 90% confidence interval width of the least toxic time had to be<6 h. The least toxic time detection based on the incidence of other toxicities was also analyzed. The time of least drug toxic was estimated using a logistic regression model assuming that the logit transformation of the toxicity rate follows a sinusoidal distribution over 24 h. The bootstrap technique was used to obtain the 90% confidence interval. The least toxic time of G3-4 neutropenia was observed at 21:00 h with a non-significant 90% CI. Secondary endpoint analyses indicated the least toxic time could differ when based on other toxicity parameters (e.g., a significant least toxic time of 17:00 h was observed for G3-4 leucopenia), in agreement with animal data. The least toxic time of 10:30 h was estimated for any G3-4 gastrointestinal toxicity. This results of this study do not allow us to recommend an optimal time for vinorelbine administration. It has highlighted, however, the inherent methodological difficulties in the conduct of such a trial in the human setting. It indicates that future optimal time-finding trials should have tolerability and/or activity as the primary endpoint in place of a particular toxicity. The randomized optimal time-finding design may be used to identify the best time of chemotherapy administration.