Effects of CYP3A4 and CYP2C9 genotype on systemic anastrozole and fulvestrant concentrations in SWOG S0226

Objective & methods: This study tested associations of genotype-predicted activity of CYP3A4, other pharmacogenes, SLC28A7 (rs11648166) and ALPPL2 (rs28845026) with systemic concentrations of the endocrine therapies anastrozole and fulvestrant in SWOG S0226 trial participants. Results: Participants in the anastrozole-only arm with low CYP3A4 activity (i.e. CYP3A4*22 carriers) had higher systemic anastrozole concentrations than patients with high CYP3A4 activity (β-coefficient = 10.03; 95% CI: 1.42, 18.6; p = 0.025). In an exploratory analysis, participants with low CYP2C9 activity had lower anastrozole concentrations and higher fulvestrant concentrations than participants with high CYP2C9 activity. Conclusion: Inherited genetic variation in CYP3A4 and CYP2C9 may affect concentrations of endocrine therapy and may be useful to personalize dosing and improve treatment outcomes.

Overall Survival with Fulvestrant plus Anastrozole in Metastatic Breast Cancer

BACKGROUND

We previously reported prolonged progression-free survival and marginally prolonged overall survival among postmenopausal patients with hormone receptor-positive metastatic breast cancer who had been randomly assigned to receive the aromatase inhibitor anastrozole plus the selective estrogen-receptor down-regulator fulvestrant, as compared with anastrozole alone, as first-line therapy. We now report final survival outcomes.

METHODS

We randomly assigned patients to receive either anastrozole or fulvestrant plus anastrozole. Randomization was stratified according to adjuvant tamoxifen use. Analysis of survival was performed by means of two-sided stratified log-rank tests and Cox regression. Efficacy and safety were compared between the two groups, both overall and in subgroups.

RESULTS

Of 707 patients who had undergone randomization, 694 had data available for analysis. The combination-therapy group had 247 deaths among 349 women (71%) and a median overall survival of 49.8 months, as compared with 261 deaths among 345 women (76%) and a median overall survival of 42.0 months in the anastrozole-alone group, a significant difference (hazard ratio for death, 0.82; 95% confidence interval [CI], 0.69 to 0.98; P = 0.03 by the log-rank test). In a subgroup analysis of the two strata, overall survival among women who had not received tamoxifen previously was longer with the combination therapy than with anastrozole alone (median, 52.2 months and 40.3 months, respectively; hazard ratio, 0.73; 95% CI, 0.58 to 0.92); among women who had received tamoxifen previously, overall survival was similar in the two groups (median, 48.2 months and 43.5 months, respectively; hazard ratio, 0.97; 95% CI, 0.74 to 1.27) (P = 0.09 for interaction). The incidence of long-term toxic effects of grade 3 to 5 was similar in the two groups. Approximately 45% of the patients in the anastrozole-alone group crossed over to receive fulvestrant.

CONCLUSIONS

The addition of fulvestrant to anastrozole was associated with increased long-term survival as compared with anastrozole alone, despite substantial crossover to fulvestrant after progression during therapy with anastrozole alone. The results suggest that the benefit was particularly notable in patients without previous exposure to adjuvant endocrine therapy. (Funded by the National Cancer Institute and AstraZeneca; ClinicalTrials.gov number, NCT00075764.).

Abstract PD5-07: A phase III randomized trial of anastrozole and fulvestrant versus anastrozole or sequential anastrozole and fulvestrant as first-line therapy for postmenopausal women with metastatic breast cancer: Final survival outcomes of SWOG S0226

Background: Anastrozole depletes estrogen via aromatase inhibition and fulvestrant binds and degrades estrogen receptor. In a Phase III trial we compared the concurrent use of these agents to anastrozole alone or sequential anastrozole and fulvestrant in first-line therapy of hormone receptor-positive metastatic breast cancer in postmenopausal women, and demonstrated improved progression-free (PFS) and overall survival (OS)-NEJM 2012. Now we report PFS and OS five years after the initial positive findings. Methods: A total of 707 patients were randomized to either 1 mg anastrozole P.O. daily (Arm 1) or to the combination of anastrozole and fulvestrant (Arm 2). Fulvestrant was administered as a loading dose of 500 mg on day 1, 250 mg on days 14, 28 and monthly thereafter. Randomization was stratified by adjuvant tamoxifen use. The primary endpoint was PFS with OS a secondary outcome. 40% patients not in visceral crisis crossed over to fulvestrant after progression on arm 1. Analysis of survival was by 2-sided stratified log-rank tests and Cox regression using intent-to-treat. Subset analyses include treatment effect by adjuvant tamoxifen exposure, initial sites of metastases and time from diagnosis. Results: There were 646 PFS events (328 and 318 for arms 1 and 2, respectively) among 694 eligible patients (345 and 349, respectively). Overall, median PFS was 13.5 months for arm 1 and 15.0 months for the arm 2 (log-rank p=0.007; HR=0.81 (95% CI 0.69-0.94)). This benefit extended similarly in visceral and non-visceral subgroups. In subset analysis for Arms 1 and 2, respectively, in tamoxifen-naive women (60%, n=414), median PFS was 12.7 vs. 16.7 months (log-rank p=0.002; HR=0.73 (95% CI 0.60-0.89) while in women exposed to tamoxifen, median PFS was 13.9 vs. 13.6 months (log-rank p=0.57; HR=0.93 (95% CI 0.73-1.19)). An improved OS in the combination arm was seen, median OS 42 and 50 months in arms 1 and 2, based on 261 and 247 deaths, respectively (log-rank p=0.028; HR=0.82 (95% CI 0.69-0.98)). In subset analysis in tamoxifen-naive women, median OS was 40.3 vs. 52.2 months for Arms 1 and 2, respectively (log-rank p=0.007; HR=0.73 (95% CI 0.58-0.92)) while in women exposed to tamoxifen, median OS was 43.5 vs. 48.2 months (log-rank p=0.85; HR=0.97 (95% CI 0.74-1.27). Patients with initial diagnosis >10 years benefitted most from the combination (HR=0.66 (95% CI 0.49-0.89)) regardless of tamoxifen exposure. Patients in Arm 1 who crossed over had post-progression survival similar to post-progression survival of Arm 2 patients. Conclusion: The addition of fulvestrant to anastrozole was associated with improved long-term PFS and OS compared to anastrozole alone, despite the use of fulvestrant at a dose lower than the approved, and despite the substantial cross over to fulvestrant after progression on anastrozole alone. The benefit was especially notable in those without recent exposure to adjuvant endocrine therapy. Ongoing translational medicine studies will further refine the need for up front fulvestrant. ClinicalTrials.gov:NCT00075764. Funding: NIH/NCI U10CA180888, U10CA180819 and AstraZeneca.

Citation Format: Mehta RS, Barlow WE, Albain KS, Vandenberg TA, Dakhil SR, Tirumali NL, Lew DL, Hayes DF, Gralow JR, Linden HM, Livingston RB, Hortobagyi GN. A phase III randomized trial of anastrozole and fulvestrant versus anastrozole or sequential anastrozole and fulvestrant as first-line therapy for postmenopausal women with metastatic breast cancer: Final survival outcomes of SWOG S0226 [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD5-07.

Fulvestrant decreases anastrozole drug concentrations when taken concurrently by patients with metastatic breast cancer treated on SWOG study S0226

AIMS

In the SWOG S0226 trial the combination of anastrozole plus fulvestrant (n = 349) was superior to anastrozole alone (n = 345) in hormone receptor (HR)-positive metastatic breast cancer. Here we report a pharmacokinetic subset analysis investigating a possible drug interaction between anastrozole and fulvestrant.

METHODS

Post-menopausal patients with HR-positive metastatic breast cancer were randomized to anastrozole with or without concurrent fulvestrant. Blood samples were collected at 2, 4, 6 and 8 months, just prior to receiving the next dose of anastrozole and fulvestrant. Drug concentrations were measured via LC/MS-MS. Anastrozole concentration was compared in patients on anastrozole alone vs. patients on concomitant fulvestrant. Comparisons were made at each time point using parametric tests and over time using a linear mixed effects model.

RESULTS

A total of 483 anastrozole concentration measurements were included, 224 samples from 64 patients on the anastrozole alone arm and 259 from 73 patients on the combination arm. The mean anastrozole concentration in the combination arm was significantly lower than that in the anastrozole alone arm at each sample collection time (all P < 0.01) and in the mixed effects model (an estimated difference of 9.85 ng ml(-1) (95% CI 5.69, 14.00 ng ml(-1) ), P < 0.001).

CONCLUSION

A significant pharmacokinetic drug interaction was detected, in which the addition of fulvestrant to anastrozole treatment decreased the trough anastrozole concentration. Further research is needed to verify whether this interaction affects treatment efficacy and to determine the pharmacological mechanism by which this interaction occurs.

Competing risks of death in younger and older postmenopausal breast cancer patients

AIM: To show a new paradigm of simultaneously testing whether breast cancer therapies impact other causes of death.

METHODS: MA.14 allocated 667 postmenopausal women to 5 years of tamoxifen 20 mg/daily ± 2 years of octreotide 90 mg, given by depot intramuscular injections monthly. Event-free survival was the primary endpoint of MA.14; at median 7.9 years, the tamoxifen+octreotide and tamoxifen arms had similar event-free survival (P = 0.62). Overall survival was a secondary endpoint, and the two trial arms also had similar overall survival (P = 0.86). We used the median 9.8 years follow-up to examine by intention-to-treat, the multivariate time-to-breast cancer-specific (BrCa) and other cause (OC) mortality with log-normal survival analysis adjusted by treatment and stratification factors. We tested whether baseline factors including Insulin-like growth factor 1 (IGF1), IGF binding protein-3, C-peptide, body mass index, and 25-hydroxy vitamin D were associated with (1) all cause mortality, and if so and (2) cause-specific mortality. We also fit step-wise forward cause-specific adjusted models.

RESULTS: The analyses were performed on 329 patients allocated tamoxifen and 329 allocated tamoxifen+octreotide. The median age of MA.14 patients was 60.1 years: 447 (82%) < 70 years and 120 (18%) ≥ 70 years. There were 170 deaths: 106 (62.3%) BrCa; 55 (32.4%) OC, of which 24 were other malignancies, 31 other causes of death; 9 (5.3%) patients with unknown cause of death were excluded from competing risk assessments. BrCa and OC deaths were not significantly different by treatment arm (P = 0.40): tamoxifen patients experienced 50 BrCa and 32 OC deaths, while tamoxifen + octreotide patients experienced 56 BrCa and 23 OC deaths. Proportionately more deaths (P = 0.004) were from BrCa for patients < 70 years, where 70% of deaths were due to BrCa, compared to 54% for those ≥ 70 years of age. The proportion of deaths from OC increased with increasing body mass index (BMI) (P = 0.02). Higher pathologic T and N were associated with more BrCa deaths (P < 0.0001 and 0.002, respectively). The cumulative hazard plot for BrCa and OC mortality indicated the concurrent accrual of both types of death throughout follow-up, that is the existence of competing risks of mortality. MA.14 therapy did not impact mortality (P = 0.77). Three baseline patient and tumor characteristics were differentially associated with cause of death: older patients experienced more OC (P = 0.01) mortality; patients with T1 tumors and hormone receptor positive tumors had less BrCa mortality (respectively, P = 0.01, P = 0.06). Additionally, step-wise cause-specific models indicated that patients with node negative disease experienced less BrCa mortality (P = 0.002); there was weak evidence that, lower C-peptide (P = 0.08) was associated with less BrCa mortality, while higher BMI (P = 0.01) was associated with worse OC mortality.

CONCLUSION: We demonstrate here a new paradigm of simultaneous testing of therapeutics directed at multiple diseases for which postmenopausal women are concurrently at risk. Octreotide LAR did not significantly impact breast cancer or other cause mortality, although different baseline factors influenced type of death.

Abstract P4-03-09: Time points to diagnosis and treatment of invasive breast cancer in southwestern Ontario

Background Delays in breast cancer diagnosis and treatment are associated with increased tumour size at presentation, higher incidence of lymph node metastasis, higher relapse rates and lower 5-year survival rates in some studies. Diagnosis and treatment of breast cancer is complex, involving many health care practitioners at multiple locations. New advances in diagnostic and prognostic indicators make the process ever more complex. We reviewed the timing of crucial events in breast cancer diagnosis and treatment in Southwestern Ontario. Methods: Two time periods (2001, 2011) were assessed. Patients with new early invasive breast cancer with specific TNM criteria (T1c or greater plus any N, or any T plus N1-3; M0) were included. Data collection and analysis explored significant time points from first suspicion of malignancy, to diagnosis and definitive treatment, as well as patient demographic information. Results: 300 and 451 eligible patients were identified in 2001 and 2011 cohorts. Distribution of T and N status by cohort was compared by Chi-square test and time from first suspicion to diagnosis by Wilcoxon testing. The proportion of patients in which the time from first suspicion (clinical by lay person or health professional or by imaging) to pathological diagnosis exceeded two months increased from 20.4% in 2001 to 42.1% in 2011. There were no differences in time from first suspicion to diagnosis when analyzed by age (p = 0.54) or location (p = 0.50). Pathological T2-4 status at diagnosis increased from 48.4% in 2001 to 56.8% in 2011, and N2-3 status increased from 7.3% to 12.6%. Patients who had mammograms increased from 52.7% to 59.4%. A positive or suspicious mammogram was the first sign in 36% and 39.1% of cases. There was a trend towards more pathological diagnoses and definitive surgeries at tertiary centers compared to community hospitals. Conclusions: There is a longer time interval from first suspicion of malignancy to pathological diagnosis in 2011 compared to 2001 for both urban and rural populations. The number of non-low risk, non-metastatic cancers at diagnosis increased by 50% over the time interval studied (300 v 451), but number of T2-T4 non-metastatic cancers increased by 77% (145 v 256) and N2,3 cancers by 136% (22 v 52). This is despite more patients receiving mammograms (52.7% v 59.4%). Delays in breast cancer treatment are multifactorial, including both system-, and patient-related factors. This is an under-researched area and more investigation is needed to understand the reasons for the diagnostic delays and more serious cancers at presentation in order to improve outcomes. Reasons for higher proportions of advanced cancers will be discussed.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-03-09.

Combination anastrozole and fulvestrant in metastatic breast cancer

BACKGROUND

The aromatase inhibitor anastrozole inhibits estrogen synthesis. Fulvestrant binds and accelerates degradation of estrogen receptors. We hypothesized that these two agents in combination might be more effective than anastrozole alone in patients with hormone-receptor (HR)-positive metastatic breast cancer.

METHODS

Postmenopausal women with previously untreated metastatic disease were randomly assigned, in a 1:1 ratio, to receive either 1 mg of anastrozole orally every day (group 1), with crossover to fulvestrant alone strongly encouraged if the disease progressed, or anastrozole and fulvestrant in combination (group 2). Patients were stratified according to prior or no prior receipt of adjuvant tamoxifen therapy. Fulvestrant was administered intramuscularly at a dose of 500 mg on day 1 and 250 mg on days 14 and 28 and monthly thereafter. The primary end point was progression-free survival, with overall survival designated as a prespecified secondary outcome.

RESULTS

The median progression-free survival was 13.5 months in group 1 and 15.0 months in group 2 (hazard ratio for progression or death with combination therapy, 0.80; 95% confidence interval [CI], 0.68 to 0.94; P=0.007 by the log-rank test). The combination therapy was generally more effective than anastrozole alone in all subgroups, with no significant interactions. Overall survival was also longer with combination therapy (median, 41.3 months in group 1 and 47.7 months in group 2; hazard ratio for death, 0.81; 95% CI, 0.65 to 1.00; P=0.05 by the log-rank test), despite the fact that 41% of the patients in group 1 crossed over to fulvestrant after progression. Three deaths that were possibly associated with treatment occurred in group 2. The rates of grade 3 to 5 toxic effects did not differ significantly between the two groups.

CONCLUSIONS

The combination of anastrozole and fulvestrant was superior to anastrozole alone or sequential anastrozole and fulvestrant for the treatment of HR-positive metastatic breast cancer, despite the use of a dose of fulvestrant that was below the current standard. (Funded by the National Cancer Institute and AstraZeneca; SWOG ClinicalTrials.gov number, NCT00075764.).

Randomized trial of tamoxifen versus combined tamoxifen and octreotide LAR Therapy in the adjuvant treatment of early-stage breast cancer in postmenopausal women: NCIC CTG MA.14

PURPOSE

Somatostatin analogs act directly on breast cancer cells and indirectly on insulin and insulin-like growth factor 1 (IGF-1) levels. This trial was undertaken to assess whether octreotide would lower insulin and IGF-1 levels and reduce risk of breast cancer recurrence.

PATIENTS AND METHODS

The NCIC CTG MA.14 (NCIC Clinical Trials Group MA.14) trial randomly assigned postmenopausal women to 5 years of tamoxifen 20 mg daily (TAM) or TAM plus 2 years of octreotide 90 mg depot intramuscular injections monthly (TAM-OCT) as adjuvant therapy. The primary end point was event-free survival (EFS). Secondary end points were relapse-free survival (RFS), overall survival (OS), toxicity, and effects of treatment on IGF physiology.

RESULTS

Among 667 women with a median follow-up of 7.9 years, 220 events occurred-108 with TAM-OCT and 112 with TAM. Adjusted hazard ratios (HRs; TAM-OCT to TAM) were 0.93 for EFS (95% CI, 0.71 to 1.22; P = .62), 0.84 for RFS (95% CI, 0.59 to 1.18; P = .31), and 0.97 for OS (95% CI, 0.69 to 1.37; P = .86). Among patients with normal baseline gallbladder imaging, cholecystectomy was required in 23.0% of those receiving TAM-OCT but in only 1.4% of those receiving TAM (P < .001). At 4 months, TAM-OCT had significantly (P < .001) lowered IGF-1, IGF binding protein 3, and C-peptide levels. Older age (P = .02), tumor size (P = .001), nodal status (P = .01), high C-peptide levels (P < .001), and higher body mass index (BMI) in models excluding C-peptide (P < .001) were associated with poorer EFS in multivariate analysis.

CONCLUSION

Octreotide-related changes in circulating IGF-1 and C-peptide levels were statistically significant. Octreotide did not add significant clinical benefit. High C-peptide levels (surrogate for insulin secretion rate) and high BMI were associated with poor outcome.

A randomized placebo-controlled study of tamoxifen after adjuvant chemotherapy in premenopausal women with early breast cancer (National Cancer Institute of Canada--Clinical Trials Group Trial, MA.12)

BACKGROUND

In the early 1990s, the role of adjuvant tamoxifen in premenopausal women with early breast cancer (EBC) was not established. Similarly, optimum timing relative to adjuvant chemotherapy and efficacy of tamoxifen in hormone receptor-negative tumors were unclear.

PATIENTS AND METHODS

Premenopausal women with EBC, any hormone receptor status, after surgery received standard adjuvant chemotherapy [doxorubicin (adriamycin)/cyclophosphamide, cyclophosphamide/methotrexate/5-fluorouracil, or cyclophosphamide/epirubicin/5-fluorouracil] followed by randomization to tamoxifen or placebo for 5 years. Outcomes were overall survival (OS), disease-free survival (DFS), toxicity, and compliance with therapy.

RESULTS

Median follow-up for 672 women was 9.7 years. Multivariate analysis showed improved DFS [78.2% versus 71.3% at 5 years; hazard ratio (HR) 0.77; P = 0.056] and a trend for improved OS (86.6% versus 82.1% at 5 years; HR 0.78; P = 0.12). There was no evidence of greater benefit for the receptor-positive subgroup. Compliance with treatment was suboptimal in both arms, with 103 (31%) women on tamoxifen and 70 (21%) on placebo-stopping therapy early because of toxicity, refusal, or other choices.

CONCLUSIONS

Adjuvant tamoxifen, given after chemotherapy to premenopausal women with EBC, improved 5-year DFS. Poor compliance may have reduced treatment efficacy.

A phase II study of ZD0473 given as a short infusion every 3 weeks to patients with advanced or metastatic breast cancer: a National Cancer Institute of Canada Clinical Trials Group trial, IND 129

BACKGROUND

ZD0473 is a new generation platinum compound with activity against a wide range of human tumor cell lines and xenografts, including carboplatin- and cisplatin-resistant lines. A phase II study of ZD0473 in advanced breast cancer was initiated by the National Cancer Institute of Canada Clinical Trials Group.

PATIENTS AND METHODS

Women with metastatic breast cancer, measurable disease, an Eastern Cooperative Oncology Group performance status of up to two, and a maximum of one prior cytotoxic agent for recurrent disease were enrolled and treated at 120 mg/m(2) every 3 weeks. After 13 patients were enrolled, the dose was increased to 150 mg/m(2) on the basis of emergent data from studies ongoing at the time.

RESULTS

Thirty-three women were evaluable for toxicity and 26 patients for response. Toxicity was mainly hematological with grade 3/4 thrombocytopenia in 12 of 20 patients (60%) treated at 150 mg/m(2) and grade 3 thrombocytopenia in three of 13 patients (23%) at 120 mg/m(2). Grade 3/4 neutropenia occurred in 15 patients (75%) at 150 mg/m(2) and two patients (10%) at 120 mg/m(2). Non-hematological toxicities were generally mild or moderate. There was one partial response seen for a response rate of 3.8% (95% confidence interval 0.1% to 19.5%) and stable disease in 15 patients.

CONCLUSION

ZD0473 has minor activity as a single agent in metastatic breast cancer. Combinations with other drugs including docetaxel are ongoing and may be of interest.

Prospective randomized trial of docetaxel versus mitomycin plus vinblastine in patients with metastatic breast cancer progressing despite previous anthracycline-containing chemotherapy. 304 Study Group

PURPOSE

This phase III study compared docetaxel with mitomycin plus vinblastine (MV) in patients with metastatic breast cancer (MBC) progressing despite previous anthracycline-containing chemotherapy.

PATIENTS AND METHODS

Patients (n=392) were randomized to receive either docetaxel 100 mg/m2 intravenously (i.v.) every 3 weeks (n=203) or mitomycin 12 mg/m2 i.v. every 6 weeks plus vinblastine 6 mg/m2 i.v. every 3 weeks (n=189), for a maximum of 10 3-week cycles.

RESULTS

In an intention-to-treat analysis, docetaxel produced significantly higher response rates than MV overall (30.0% v 11.6%; P < .0001), as well as in patients with visceral involvement (30% v 11%), liver metastases (33% v 7%), or resistance to previous anthracycline agents (30% v 7%). Median time to progression (TTP) and overall survival were significantly longer with docetaxel than MV (19 v 1 weeks, P=.001, and 1 1.4 v 8.7 months, P=.0097, respectively). Neutropenia grade 3/4 was more frequent with docetaxel (93.1 % v62.5%; P < .05); thrombocytopenia grade 3/4 was more frequent with MV (12.0% v 4.1%; P < .05). Severe acute or chronic nonhematologic adverse events were infrequent in both groups. Withdrawal rates because of adverse events (MV, 10.1%; docetaxel, 13.8%) or toxic death (MV, 1.6%; docetaxel, 2.0%) were similar in both groups. Quality-of-life analysis was limited by a number of factors, but results were similar in both groups.

CONCLUSION

Docetaxel is significantly superior to MV in terms of response, TTP, and survival. The safety profiles of both therapies are manageable and tolerable. Docetaxel represents a clear treatment option for patients with MBC progressing despite previous anthracycline-containing chemotherapy.

Docetaxel vs mitomycin plus vinblastine in anthracycline-resistant metastatic breast cancer

This nonblinded, multicenter, randomized phase III study compares the median time to progression (primary endpoint), response rate, and quality of life, safety, and survival of docetaxel (Taxotere) vs mitomycin (Mutamycin) plus vinblastine (Velban) in patients with metastatic breast cancer in whom previous anthracycline-containing chemotherapy has failed. Patients were randomized to receive an intravenous infusion of either 100 mg/m2 of docetaxel for 1 hour every 3 weeks, or 12 mg/m2 of mitomycin every 6 weeks plus 6 mg/m2 of vinblastine every 3 weeks. This preliminary analysis presents data on 200 patients among 392 patients recruited. Median time to progression was longer in the group treated with docetaxel compared with the mitomycin/vinblastine group (17 vs 9 weeks). The overall response rates were higher with docetaxel (28% vs 13%, respectively), and fewer patients in the docetaxel group had progressive disease as their best overall response (29% vs 48%). As expected, thrombocytopenia was more common in the mitomycin/vinblastine group, and neutropenia occurred more frequently in the docetaxel group. Severe fluid retention in the docetaxel group (8.7%) resulted in treatment discontinuation in 5 patients (5%). Severe thrombocytopenia (12%) and constipation (6%) led to treatment discontinuation in 7 and 3 patients, respectively, in the mitomycin/vinblastine group. Based on this preliminary analysis, docetaxel appears to be equally as safe as and more active than mitomycin/ vinblastine in patients with metastatic breast cancer in whom previous anthracycline-containing chemotherapy has failed. These results are subject to cautious interpretation because this analysis was conducted on the first 200 patients who finished the study treatments, and these preliminary results may underestimate response and overstate treatment discontinuation rates. Thus, the final analysis on the entire patient population is necessary to confirm these preliminary findings.

Docetaxel in patients with metastatic breast cancer: a phase II study of the National Cancer Institute of Canada-Clinical Trials Group

PURPOSE

The National Cancer Institute of Canada-Clinical Trials Group (NCIC-CTG) conducted a phase II study to assess the efficacy and toxicity of docetaxel as first-line chemotherapy in metastatic breast cancer (MBC).

PATIENTS AND METHODS

Fifty-one patients with measurable MBC were studied. Three patients were ineligible and were excluded from analysis. The planned dose of docetaxel was 100 mg/m2 intravenously (i.v.) every 3 weeks. Prior adjuvant chemotherapy was allowed if at least 12 months had elapsed from completion of treatment to recurrence.

RESULTS

The most severe toxicity was granulocytopenia. Ten patients (20.8%) were hospitalized for febrile neutropenia. The protocol was amended to a starting dose of 75 mg/m2 for the last 16 patients. Sixty percent of patients experienced hypersensitivity reactions (HSRs). After two protocol amendments, the use of a premedication regimen of oral dexamethasone and i.v. H1 and H2 blockers prevented significant HSRs. Edema developed in 62% of patients and was cumulative, was present in 50% who received greater than 400 mg/m2, and was not improved by premedication regimens. Following an independent radiology review, 22 partial remissions and four complete responses in 47 assessable patients were confirmed (response rate, 55%; 95% confidence interval [CI], 40% to 69%). The response rate for 15 assessable patients registered at 75 mg/m2 was 40% (95% CI, 16% to 67%); for 32 assessable patients registered at 100 mg/m2, the response rate was 63%, (95% CI, 43% to 78%).

CONCLUSION

Docetaxel is an active agent in MBC. Its activity as a single agent is comparable to many combination chemotherapy regimens and is not affected by prior adjuvant chemotherapy. Studies are ongoing to improve its therapeutic index and to incorporate docetaxel in combination chemotherapy regimens.

New developments in chemotherapy for metastatic breast cancer

Breast cancer remains a major cause of morbidity and early death for women. Despite aggressive implementation of preventive measures including screening and adjuvant therapy, this disease will likely continue to have a significant impact unless better treatments are found. A number of new agents have recently been developed that show promising results in the setting of metastatic disease including losoxantrone, vinorelbine, edatrexate, paclitaxel and docetaxel. Some have shown exciting activity where tumor progression has occurred following anthracycline therapy. Appropriate evaluation of new chemotherapeutic agents requires a clear description of the population studied as well as standardized assessments of outcomes. Evaluations are more relevant and more quickly done in multicenter trials. Because of the heterogeneity of metastatic breast cancer and differences in outcome measurement, randomized trials continue to be essential in defining which agents are the most appropriate candidates for further study.

Phase II study of weekly edatrexate as first-line chemotherapy for metastatic breast cancer: a National Cancer Institute of Canada Clinical Trials Group study

PURPOSE

The National Cancer Institute of Canada (NCIC) Clinical Trials Group conducted a phase II study to assess the efficacy and toxicity of edatrexate, a folate antagonist, in 35 patients with metastatic breast cancer.

PATIENTS AND METHODS

The planned dose of edatrexate was 80 mg/m2/wk administered intravenously as first-line therapy. Prior adjuvant chemotherapy was allowed provided at least 12 months had elapsed from the completion of treatment to the development of recurrence.

RESULTS

Mucositis was the dose-limiting toxicity in 34 assessable patients, resulting in a mean delivered dose-intensity of 57 mg/m2/wk. Other toxicities included myelosuppression, rash, pneumonitis, and increased AST. Side effects were generally mild to moderate. The complete plus partial remission rate (13 patients; 41%) was impressive.

CONCLUSION

Edatrexate is an active agent against metastatic breast cancer, with acceptable toxicity. A lower than planned delivered dose-intensity was mainly due to mucositis.

Granulomatous hepatitis in a patient with previously treated histiocytic lymphoma

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