Docetaxel and cyclophosphamide induced remission in platinum and paclitaxel refractory ovarian cancer

Platinum-based chemotherapy is the standard treatment for advanced ovarian cancer, with response rates of 40-60%. In patients who fail platinum treatment, paclitaxel has resulted in response rates of 10-48%. Docetaxel has partial non-cross-resistance with and is twice as potent in vitro as paclitaxel in inhibiting microtubule disaggregation. The combination of docetaxel and cyclophosphamide is synergistic in pre-clinical studies and clinically active in breast cancer. We present the case of a patient with platinum and paclitaxel refractory ovarian cancer who achieved a remission with docetaxel and cyclophosphamide.

[Neurotransmitter release: a process of membrane fusion occurring in fractions of milliseconds]

INTRODUCTION

The physiological mechanisms involved in neurotransmitter release were established thanks to the pioneer work of Katz, Del Castillo and Miledi at the neuromuscular junction. They termed their work as the quantal hypothesis of synaptic transmission. This hypothesis was further established morphologically by the work of Heuser and Reese. However, the molecular events underlying this process are poorly understood. We are starting to know which proteins interact between the vesicle and plasma membrane to promote fusion and to identify which molecules participate in the sensing of cytosolic calcium.

DEVELOPMENT

Thanks to the combination of molecular biology, electrophysiology and microfluorometry, a huge amount of new information is been obtained on the mechanisms participating in synaptic transmission. This data deals with processes concerning to different pools of synaptic vesicles and their availability to reach the presynaptic membrane; the molecular events responsible for the targeting of these vesicles with the plasma membrane; the sensitivity to calcium at the presynaptic membrane; the fusion of membranes required to release the vesicle contents, and the mechanisms responsible for membrane retrieval needed for presynaptic homeostasis.

CONCLUSIONS

In this review we discuss new data regarding synaptic function. However, some key points are still a matter of controversy. Meanwhile the quantal hypothesis is valid, the precise processes by which channels and vesicles interact, membrane is recycled and vesicles reused are still controversial. New techniques should be developed to address these points.

Clinical course of breast cancer patients with metastases confined to the lungs treated with chemotherapy. The University of Texas M.D. Anderson Cancer Center experience and review of the literature

PURPOSE

To evaluate the clinical course of patients with a metastatic breast cancer (MBC) confined to the lungs and treated with doxorubicin/cyclophosphamide-containing chemotherapy (DC-CT).

PATIENTS AND METHODS

Between 1973 and 1985, 1581 patients with MBC were treated with DC-CT at M.D. Anderson Cancer Center. Data for 88 patients (5.6%) with metastases confined to the lungs were reviewed to correlate various clinical characteristics with response to treatment and survival.

RESULTS

The overall response rate was 76% with 33% achieving complete response (CR). The median overall survival time was 22 months (range 1-210). The 10-year survival rate was 9%. The overall response and CR rates were higher for the patients with metastases confined to the lungs (76% and 33%. respectively) than for the remainder of MBC patients (64% and 14%; P < 0.01). The 10-year survival rate was also higher (9% versus 3%, P < 0.01), but there were no differences in median overall survival rate.

CONCLUSIONS

This retrospective analysis demonstrated that patients with metastases confined to the lungs treated with DC-CT had a high objective response rate, especially high CR rates, and a median survival comparable to that of our entire population of MBC patients. A small but clinically significant percentage of patients had prolonged survival. Therefore, not all visceral sites are indicators of poor prognosis.

Hand-foot syndrome following prolonged infusion of high doses of vinorelbine

BACKGROUND

The authors reviewed the incidence of toxic skin reactions in patients with metastatic breast carcinoma (MBC) treated with vinorelbine as a continuous infusion.

METHODS

A Phase I/II protocol was designed in which vinorelbine was given as an 8-mg intravenous bolus followed by a 96-hour CI of 7-14 mg/m2/day. Sixty patients were enrolled in the study: all had MBC and had received prior chemotherapy, and they had no known dermatologic disorder.

RESULTS

Hand-foot syndrome (HFS) developed in 4 of the 60 patients. Patient 1 started with vinorelbine at 12 mg/m2/day. She developed typical HFS. In the second course, her dose was decreased to 11 mg/m2/day, but again she experienced HFS. In the third course, dexamethasone was added to the regimen, and no HFS was observed in the remaining six courses. Patient 2 started with a dose of 9 mg/m2/ day. She received four courses without complications; but when the vinorelbine dose was escalated to 10 mg/m2/day, HFS developed. Patient 3 started with a vinorelbine dose of 14 mg/m2/day. She developed mucositis during the first two courses and HFS during the third. Patient 4 received vinorelbine at a dose of 13 mg/m2/day and developed significant HFS. All patients had complete dermatologic recovery. No toxic skin reactions were observed in 14 patients receiving vinorelbine doses of <10 mg/m2/day, whereas 4 of 46 treated at 10-14 mg/m2/day developed HFS, suggesting a relationship of dose to HFS occurrence.

CONCLUSIONS

Longer infusions of vinorelbine are occasionally associated with HFS. The pathophysiology is not completely clear, but a relationship of HFS occurrence to dose is suggested. Steroids were effective as prophylaxis in one patient.

Population pharmacokinetics/pharmacodynamics of docetaxel in phase II studies in patients with cancer

PURPOSE

The population pharmacokinetic/pharmacodynamic (PK/PD) approach was prospectively integrated in the clinical development of docetaxel to assess the PK profile in a large population of patients and investigate systemic exposure as a prognostic factor for clinical outcome.

PATIENTS AND METHODS

PK analysis was performed at first course in 24 phase II studies of docetaxel monotherapy using four randomized limited-sampling schedules. Bayesian estimates of clearance (CL), area under the concentration-time curve (AUC), and peak and duration of plasma levels greater than threshold levels were used as measures of exposure. PD data included for efficacy, response rate, time to first response, and time to progression (TTP) in breast cancer and non-small-cell lung cancer (NSCLC), and for toxicity, grade 4 neutropenia, and febrile neutropenia at first course and time to onset of fluid retention. PK/PD analysis was conducted using logistic and Cox multivariate regression models.

RESULTS

PK protocol implementation was successful. Most of the patients registered (721 of 936, 77%) were sampled and 68% were assessable for PK (640 patients). First-course docetaxel AUC was a significant predictor (P = .0232) of TTP in NSCLC (n = 151). Docetaxel CL was a strong independent predictor (P < .0001) of both grade 4 neutropenia and febrile neutropenia (n = 582). Cumulative dose was the strongest predictor (P < .0001) of the time to onset of fluid retention (n = 631). However, the duration of exposure over 0.20 micromol/L (0.16 microg/mL) at first course was an independent predictor (P = .0029). Few patients (n = 25, 4%) received the recommended dexamethasone premedication.

CONCLUSION

First-course docetaxel PK is a predictor of first-course hematologic toxicity, but also of fluid retention, which is cumulative in nature. Patients with elevated hepatic enzymes have a 27% reduction in docetaxel CL and are at a higher risk of toxicity. A starting dose of 75 mg/m2 is currently being evaluated in this population. Prospective implementation of large-scale population PK/PD evaluation is feasible in early drug development and this approach generates clinically relevant findings.

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.

Combination docetaxel/cyclophosphamide in patients with advanced solid tumors

Preclinical studies show that docetaxel (Taxotere) and cyclophosphamide (Cytoxan, Neosar) are synergistic against MA 13/C mammary adenocarcinoma. Both agents are highly active as monotherapy in a number of tumors, including metastatic breast cancer. Therefore, we performed a phase I dose-finding study to determine the maximum tolerated dose of this combination regimen in patients with advanced solid tumors. A total of 45 patients were enrolled and received cyclophosphamide followed by docetaxel, both administered as 1-hour intravenous infusions once every 3 weeks. The dose levels of cyclophosphamide/docetaxel were 600/60 mg/m2 (group 0), 600/75 mg/m2 (group I), 700/75 mg/m2 (group 2), 800/75 mg/m2 (group 3), 800/85 mg/m2 (group 4), 800/75 mg/m2 (group 5), and 800/85 mg/m2 (group 6). Patients with dose-limiting neutropenia in groups 5 and 6 received 300 micrograms of granulocyte colony-stimulating factor (G-CSF) (filgrastim [Neupogen]) support on days 2 through 9 during subsequent cycles of chemotherapy. All patients received premedication with 8 mg of dexamethasone twice daily for 5 days, beginning 1 day prior to chemotherapy. The dose-limiting toxicity was neutropenia fever. The recommended dose for phase II studies of cyclophosphamide/docetaxel is 700/75 mg/m2 in previously treated patients and 800/75 mg/m2 in previously untreated patients. G-CSF support did not allow for further dose escalation. Preliminary results from this phase I trial indicate that the combination of docetaxel and cyclophosphamide produced an objective response rate of 69% in 32 patients with metastatic breast cancer (including 3 patients who achieved complete responses).

Docetaxel as single-agent therapy in metastatic breast cancer: clinical efficacy

The potential importance of docetaxel as a chemotherapeutic agent for the treatment of metastatic breast cancer has been documented in approximately 575 patients enrolled in phase II clinical studies in North America, Europe, and Japan. First-line treatment with docetaxel 100 mg/m2 intravenously over 1 hour every 3 weeks produced objective responses in 59% of patients (intent-to-treat). In patients with anthracycline-resistant disease (disease that responded initially but then progressed or relapsed during treatment with an anthracycline), an overall intent-to-treat response rate of 41% was achieved. A 37% response rate was observed in anthracycline-refractory patients (those who had never achieved an objective response to anthracycline-based chemotherapy). Febrile neutropenia is the major dose-limiting toxicity of docetaxel; the neutropenia nadir typically has an early onset and short duration, with rapid recovery of the neutrophil count. Other hematologic effects are rare. Skin and hypersensitivity reactions can be minimized by premedication with corticosteroids. Reversible fluid retention, related to the cumulative dose of docetaxel, is also lessened by corticosteroid prophylaxis. In summary, docetaxel has shown impressive antitumor activity in the treatment of metastatic breast cancer, including the challenging population of patients whose disease progressed during treatment with an anthracycline or anthracenedione. Most of the adverse events related to docetaxel use can be circumvented or ameliorated by careful patient selection and routine premedication with corticosteroids, and improved methods of managing side effects are being actively studied. Docetaxel is thus expected to play an increasingly prominent role in the management of patients with metastatic breast cancer.

Docetaxel and cyclophosphamide in patients with advanced solid tumors

This trial was designed to determine the recommended maximum tolerated dose (MTD), toxicity, pharmacokinetics, and efficacy of docetaxel (Taxotere) and cyclophosphamide (Cytoxan, Neosar) for phase II studies. Both drugs were administered to 39 patients with advanced solid tumors, 26 of whom had breast cancer. Docetaxel doses ranged from 60 to 85 mg/m2 and cyclophosphamide doses ranged from 600 to 800 mg/m2. All patients received steroid prophylaxis. The MTDs for patients with a history of prior chemotherapy were 75 mg/m2 of docetaxel and 700 mg/m2 of cyclophosphamide. For patients with no prior chemotherapy, the MTDs were 75 mg/m2 of docetaxel and 800 mg/m2 of cyclophosphamide. The dose-limiting toxicity was neutropenic fever, observed in 41% of patients and 13% of cycles. Addition of granulocyte colony-stimulating factor (G-CSF, filgrastim [Neupogen]) did not permit further dose escalation, although it did result in briefer periods of neutropenia.

Sequence-dependent alteration of doxorubicin pharmacokinetics by paclitaxel in a phase I study of paclitaxel and doxorubicin in patients with metastatic breast cancer

PURPOSE

To determine whether a schedule-dependent interaction occurs when paclitaxel and doxorubicin are administered sequentially.

PATIENTS AND METHODS

Ten patients with metastatic breast cancer received paclitaxel 125 mg/m2 over 24 hours either immediately before or after doxorubicin 48 mg/m2 over 48 hours as the initial chemotherapy treatment. Two such courses were given, and the sequence of administration was reversed after course 1. In cohort 1, paclitaxel preceded doxorubicin for course 1. In cohort 2, doxorubicin preceded paclitaxel for course 1. Doxorubicin levels were measured serially during the infusion and for 24 hours following it. Patients were assessed clinically for the occurrence of stomatitis and infection and granulocyte counts were measured twice weekly.

RESULTS

Eight patients had complete pharmacokinetic sampling for both courses. The mean end-of-infusion plasma doxorubicin concentrations (Cmax) were 70% higher in the paclitaxel-doxorubicin sequence compared with the reverse sequence (45 +/- 8 ng/mL v 26 +/- 5 ng/ mL). The mean doxorubicin clearance was 32% lower in the paclitaxel-doxorubicin sequence (34.3 +/- 10.3 L/h v 51.6 +/- 16.1 L/h, P < .01). Clinically, hematologic and mucosal toxic effects were worse in the paclitaxel-doxorubicin sequence. The median absolute granulocyte count was 0.2/microL in the paclitaxel-doxorubicin sequence and 1.3/microL in the doxorubicin-paclitaxel sequence. Seven of 10 patients who received the paclitaxel-doxorubicin sequence had grade 2 (n = 4) or 3 (n = 3) stomatitis, while only one of 10 patients who received the doxorubicin-paclitaxel sequence had grade 2 stomatitis and none had grade 3.

CONCLUSION

When paclitaxel by 24-hour infusion precedes doxorubicin by 48-hour infusion, doxorubicin clearance is reduced by nearly one third, which results in grade 2 and 3 stomatitis. To prevent this effect when paclitaxel (by 24-hour infusion) and doxorubicin are administered sequentially, doxorubicin should be given first. The mechanisms for this effect are under investigation.

Treatment of patients resistant to paclitaxel therapy

Although the taxoid drugs, paclitaxel (Taxol) and docetaxel (Taxotere) have a broadly similar mechanism of action, there are notable differences in their activities and they are distinct agents. Docetaxel is more potent than paclitaxel with regard to the promotion of the polymerization of tubulin and the inhibition of depolymerization, and has greater antitumour activity in many in vitro and in vivo tumour model systems. The development of drug resistance is a major problem in the treatment of metastatic breast cancer and observations indicating only partial cross-resistance between docetaxel and paclitaxel in vitro, combined with supporting clinical evidence of activity in patients with previously-treated tumours, including anthracycline-resistant breast cancer, led to the implementation of a prospective study of docetaxel treatment in patients with paclitaxel-resistant disease. Preliminary results in 27 patients recruited to this ongoing study indicate that docetaxel has activity in paclitaxel-resistant metastatic breast cancer.

A randomized trial of minoxidil in chemotherapy-induced alopecia

BACKGROUND

Hair loss is a side effect of many chemotherapeutic agents, and patients have even refused possibly palliative or lifesaving drugs because they could not accept temporary or prolonged baldness. Topical minoxidil has been shown to be effective for androgenetic alopecia and alopecia areata.

OBJECTIVE

Our purpose was to investigate the value and safety of minoxidil in chemotherapy-induced hair loss.

METHODS

Twenty-two women who were facing adjuvant chemotherapy after breast surgery were registered in a protocol that used a 2% minoxidil topical solution or a placebo in a randomized double-blind trial.

RESULTS

There was a statistically significant difference (favoring minoxidil) in the interval from maximal hair loss to first regrowth. Thus the period of baldness was shortened (mean, 50.2 days) in the minoxidil group.

CONCLUSION

Minoxidil decreased the duration of alopecia caused by chemotherapy. There were no significant side effects.

Phase II trial of docetaxel: a new, highly effective antineoplastic agent in the management of patients with anthracycline-resistant metastatic breast cancer

PURPOSE

To determine the efficacy (objective response rate and duration of response and survival) and toxicity of docetaxel in patients with strictly defined anthracycline-resistant metastatic breast cancer (MBC).

PATIENTS AND METHODS

Thirty-five patients with bidimensionally measurable MBC who had progressive disease while receiving anthracycline-containing chemotherapy were registered onto the phase II trial. Docetaxel was administered at a dose of 100 mg/m2 over 1 hour every 21 days.

RESULTS

Thirty-four patients were assessable for disease response; 18 (53%; 95% confidence interval [CI], 35% to 70%) achieved a partial response. The median times to disease progression and survival duration were 7.5 and 13.5 months, respectively, for responding patients. The median overall survival duration was 9 months. Two hundred eight cycles (median, five) of docetaxel were administered. Neutropenia with less than 500 cells/microL developed in 31 of 35 patients; it was complicated by fever in 30 (14%) of 208 cycles and in 18 (51%) of 35 patients, including one treatment-related death. Fluid retention was seen in 15 (43%) of 35 patients, including pleural effusions in 11 patients (31%). Moderate skin toxicity, asthenia, and myalgia were observed in 16%, 58%, and 37% of cycles, respectively.

CONCLUSION

Docetaxel has the highest reported antitumor activity in anthracycline-resistant MBC. High objective response rates were seen in patients with visceral-dominant involvement, multiple metastatic sites, or extensive previous therapy. Docetaxel is associated with severe but reversible neutropenia, asthenia, and cumulative dose-related fluid retention. Dexamethasone decreased the frequency and severity of skin toxicity and appeared to ameliorate fluid retention.

Phase I clinical and pharmacological study of suppression of human antimouse antibody response to monoclonal antibody L6 by deoxyspergualin

Development of human antimouse antibody (HAMA) is a major limiting factor in the application of murine mAb for clinical use. A novel immunomodulatory drug, deoxyspergualin (DSG), has shown potential to suppress antimouse antibody response in preclinical model systems. We conducted a Phase I trial to determine the effect of DSG on HAMA response to murine mAb L6 administered to patients with advanced cancers (in previous trials, this antibody elicited HAMA in two-thirds of the treated patients). L6 mAb was administered at a fixed dose of 200 mg/m2 on days 1-5. DSG was administered at doses of 50 mg/m2 [dose level (dl) 1] or 150 mg/m2 (dls II and III) on days 1-7. Treatment courses were repeated every 6 weeks (dls I and II) or every 3 weeks (dl III). HAMAs were quantitated by a commercially available ELISA assay (ImmuSTRIP; anti-isotypic antibodies) and a radiometric assay (antiisotypic and anti-idiotypic antibodies). Pharmacokinetics of L6 and DSG was also studied in all consenting patients. Among 24 evaluable patients, 2 patients developed detectable HAMAs using the ELISA (one each at dls I and II) after a median follow-up of 122 days (P = 0.0001 as compared to historical controls). Even in the two patients who developed HAMA, the HAMA levels were quite low (160 and 181 ng/ml; historical experience, 70-38,744 ng/ml). The radiometric assay detected anti-L6 antibodies in 13 patients (4, 6, and 3 at dls I-III, respectively) after a median of 82 days. The median highest anti-L6 antibody level was 129 ng/ml (range, 21-2150). The highest anti-L6 antibody level at dl III was only 44 ng/ml. The results suggest suppression of anti-idiotypic response also. No clinical antitumor activity was observed, and no significant changes in T4/T8 subsets or immunoglobulins occurred (suggesting a lack of generalized immunosuppression). We conclude that DSG can suppress HAMA response to L6. A starting dose of 150 mg/m2/day is recommended for Phase II trials to confirm this observation.

Review of docetaxel (Taxotere), a highly active new agent for the treatment of metastatic breast cancer

Phase II studies have demonstrated that docetaxel (Taxotere; Rhône-Poulenc Rorer, Collegeville, PA) is one of the most active single agents in the treatment of metastatic breast cancer. The overall response rate as front-line therapy for metastatic disease was 59% (95% confidence interval, 51% to 67%) in five phase II trials (four of which were multicenter) when 100 mg/m2 docetaxel was infused over 1 hour every 3 weeks. In the three phase II trials reported to date of patients with metastatic cancer who had failed previous frontline therapy, 100 mg/m2 docetaxel infused over 1 hour every 3 weeks produced an objective response rate of 49% (95% confidence interval, 40% to 58%). Two of these trials specifically included patients who had progressed while receiving either an anthracycline or an anthracenedione; the overall response rate in this subset of 83 patients was 48%. The most significant acute toxicity noted in these trials was neutropenia. Grade 4 neutropenia occurred in the majority of patients but rarely resulted in treatment delays. Hypersensitivity reactions also were common in nonpremedicated patients, but were rare after the institution of premedication with antihistamines and/or glucocorticoids. A novel toxicity observed in many patients was fluid retention syndrome, with onset at a median of four to five cycles. The fluid retention was of noncardiac or renal origin, was slowly progressive with additional cycles of therapy, was reversible after cessation of the drug, and could be largely ameliorated by oral diuretics and glucocorticoid premedication. Phase III studies to further define docetaxel's role in the treatment of breast cancer are now under way.

Bioequivalence of 20-mg Once-Daily Tamoxifen Relative to 10-mg Twice-Daily Tamoxifen Regimens for Breast Cancer

Table 2 in the report entitled "Bioequivalence of 20-mg Once-Daily Tamoxifen Relative to 10-mg Twice-Daily Tamoxifen Regimens for Breast Cancer" by Buzdar et al contained an error in two column headings. It is reprinted here correctly in its entirety.

Please see the PDF for Table.

Phase II study of deoxyspergualin in metastatic breast cancer

We conducted a phase II trial of the novel immunomodulatory/cytotoxic agent 15-deoxyspergualin in patients with metastatic breast cancer who had failed treatment with front-line chemotherapy. Thirty-eight courses of treatment were administered to fourteen patients enrolled in this trial, 25 at a dose of 1800 mg/m2/d (dose level 0) and 13 at a dose of 2150 mg/m2/d (dose level +1) administered by continuous intravenous infusion for 5 days. Treatment was well tolerated with neuromuscular side-effects (myalgias, paresthesias) and granulocytopenia (nadir granulocyte count of 0.50-0.99 x 10(9)/l) in two and three courses, respectively, as the only grade III toxicities. The neuromuscular toxicity of deoxyspergualin is probably related to the occurrence of hypomagnesemia. No partial or complete responses were observed in this study. One patient achieved a minor response but had progressive disease 65 weeks after enrollment. The response was observed coincident with an increase in T4/T8 ratio in the peripheral blood. The median time to progression for the entire cohort was eight weeks (range, 4-65 weeks). There was no clinical evidence of immunosuppression and no decrease in total peripheral blood lymphocyte counts or helper T-cells was observed. At the doses and schedule employed in this trial, deoxyspergualin does not appear to have significant activity against metastatic breast cancer resistant to front-line chemotherapy. The correlation between hypomagnesemia and neuromuscular toxicity of deoxyspergualin is an intriguing, previously unknown observation and requires further investigation.

Bioequivalence of 20-mg once-daily tamoxifen relative to 10-mg twice-daily tamoxifen regimens for breast cancer

PURPOSE

We studied the bioequivalence of a new once-daily regimen of tamoxifen citrate relative to the standard twice-daily regimen of tamoxifen citrate, an established antiestrogenic treatment for breast cancer.

PATIENTS AND METHODS

Of 30 women with breast cancer, 27 completed this open, two-period, crossover randomized trial. During one 3-month period, patients took one standard 10-mg tamoxifen tablet twice daily; during the preceding or following 3-month period, patients took one of the new 20-mg tablets once daily. Pharmacokinetic profiles and safety parameters were assessed at the end of each 3-month treatment period.

RESULTS

Overall, measured concentrations of tamoxifen and its principal active metabolite, N-desmethyltamoxifen, remained relatively constant over the 24-hour sampling periods at the end of each treatment sequence. For both compounds, the percentage differences of the geometric means for all pharmacokinetic parameters indicated bioequivalence of the once-daily regimen of tamoxifen relative to the standard twice-daily regimen. Both treatment sequences were well tolerated; reported adverse events occurred at similar frequencies with the two treatment regimens.

CONCLUSION

The 20-mg tamoxifen tablet taken once daily was bioequivalent to the 10-mg tamoxifen tablet taken twice daily, with no difference in relative risk. The once-daily treatment is a simpler regimen and may facilitate compliance, which may enhance therapeutic outcomes during long-term treatment of breast cancer.