### Adjuvant Therapy 

A Phase 3 Intergroup study (Cancer and Leukemia Group B [CALGB], Eastern Cooperative Oncology Group [ECOG], North Central Cancer Treatment Group [NCCTG], and Southwest Oncology Group [SWOG]) randomized 3170 patients with node-positive breast carcinoma to adjuvant therapy with paclitaxel or to no further chemotherapy following 4 courses of doxorubicin and cyclophosphamide (AC). This multicenter trial was conducted in women with histologically positive lymph nodes following either a mastectomy or segmental mastectomy and nodal dissections. The 3 x 2 factorial study was designed to assess the efficacy and safety of 3 different dose levels of doxorubicin (A) and to evaluate the effect of the addition of paclitaxel administered following the completion of AC therapy. After stratification for the number of positive lymph nodes (1 to 3, 4 to 9, or 10+), patients were randomized to receive cyclophosphamide at a dose of 600 mg/m2 and doxorubicin at doses of either 60 mg/m2 (on day 1), 75 mg/m2 (in 2 divided doses on days 1 and 2), or 90 mg/m2 (in 2 divided doses on days 1 and 2 with prophylactic G-CSF support and ciprofloxacin) every 3 weeks for 4 courses and either paclitaxel 175 mg/m2 as a 3-hour infusion every 3 weeks for 4 additional courses or no additional chemotherapy. Patients whose tumors were positive were to receive subsequent tamoxifen treatment (20 mg daily for 5 years); patients who received segmental mastectomies prior to study were to receive breast irradiation after recovery from treatment-related toxicities. 

At the time of the current analysis, median follow-up was 30.1 months. Of the 2066 patients who were hormone receptor positive, 93% received tamoxifen. The primary analyses of disease-free survival and overall survival used multivariate Cox models, which included paclitaxel administration, doxorubicin dose, number of positive lymph nodes, tumor size, menopausal status, and estrogen receptor status as factors. Based on the model for disease-free survival, patients receiving AC followed by paclitaxel had a 22% reduction in the risk of disease recurrence compared to patients randomized to AC alone (Hazard Ratio [HR]=0.78, 95% CI, 0.67 to 0.91, p=0.0022). They also had a 26% reduction in the risk of death (HR=0.74, 95% CI, 0.60 to 0.92, p=0.0065). For disease-free survival and overall survival, p-values were not adjusted for interim analyses. Kaplan-Meier curves are shown in Figures 3 and 4. Increasing the dose of doxorubicin higher than 60 mg/m2 had no effect on either disease-free survival or overall survival.  
  


Figure 3. Disease-Free Survival: AC Versus AC+T

Figure 4. Survival: AC Versus AC+T

Subset Analyses: Subsets defined by variables of known prognostic importance in adjuvant breast carcinoma were examined, including number of positive lymph nodes, tumor size, hormone receptor status, and menopausal status. Such analyses must be interpreted with care, as the most secure finding is the overall study result. In general, a reduction in hazard similar to the overall reduction was seen with paclitaxel for both disease-free and overall survival in all of the larger subsets with one exception; patients with receptor-positive tumors had a smaller reduction in hazard (HR=0.92) for disease-free survival with paclitaxel than other groups. Results of subset analyses are shown in Table 4. 

These retrospective subgroup analyses suggest that the beneficial effect of paclitaxel is clearly established in the receptor-negative subgroup, but the benefit in receptor-positive patients is not yet clear. With respect to menopausal status, the benefit of paclitaxel is consistent (see Table 4 and Figures 5 to 8).  
  


Figure 5. Disease-Free Survival: Receptor Status Negative/Unknown AC Versus AC+T

Figure 6. Disease-Free Survival: Receptor Status Positive AC Versus AC+T

Figure 7. Disease-Free Survival: Premenopausal AC Versus AC+T

Figure 8. Disease-Free Survival: Postmenopausal AC Versus AC+T

The adverse event profile for the patients who received paclitaxel subsequent to AC was consistent with that seen in the pooled analysis of data from 812 patients (Table 10) treated with single-agent paclitaxel in 10 clinical studies. These adverse events are described in the ADVERSE REACTIONS section in tabular (Tables 10 and 13) and narrative form. 

After Failure of Initial Chemotherapy: Data from 83 patients accrued in three Phase 2 open label studies and from 471 patients enrolled in a Phase 3 randomized study were available to support the use of paclitaxel in patients with metastatic breast carcinoma. 

Phase 2 Open Label Studies: Two studies were conducted in 53 patients previously treated with a maximum of one prior chemotherapeutic regimen. Paclitaxel was administered in these two trials as a 24-hour infusion at initial doses of 250 mg/m2 (with G-CSF support) or 200 mg/m2. The response rates were 57% (95% CI: 37% to 75%) and 52% (95% CI: 32% to 72%), respectively. The third Phase 2 study was conducted in extensively pretreated patients who had failed anthracycline therapy and who had received a minimum of two chemotherapy regimens for the treatment of metastatic disease. The dose of paclitaxel was 200 mg/m2 as a 24-hour infusion with G-CSF support. Nine of 30 patients achieved a partial response, for a response rate of 30% (95% CI: 15% to 50%). 

Phase 3 Randomized Study: This multicenter trial was conducted in patients previously treated with one or two regimens of chemotherapy. Patients were randomized to receive paclitaxel at a dose of either 175 mg/m2 or 135 mg/m2 given as a 3-hour infusion. In the 471 patients enrolled, 60% had symptomatic disease with impaired performance status at study entry, and 73% had visceral metastases. These patients had failed prior chemotherapy either in the adjuvant setting (30%), the metastatic setting (39%), or both (31%). Sixty-seven percent of the patients had been previously exposed to anthracyclines and 23% of them had disease considered resistant to this class of agents. 

The overall response rate for the 454 evaluable patients was 26% (95% CI: 22% to 30%), with 17 complete and 99 partial responses. The median duration of response, measured from the first day of treatment, was 8.1 months (range: 3.4 to 18.1+ months). Overall for the 471 patients, the median time to progression was 3.5 months (range: 0.03 to 17.1 months). Median survival was 11.7 months (range: 0 to 18.9 months). 

Response rates, median survival and median time to progression for the 2 arms are given in the following table. 

The adverse event profile of the patients who received single-agent Paclitaxel Injection, USP, in the Phase 3 study was consistent with that seen for the pooled analysis of data from 812 patients treated in 10 clinical studies. These adverse events and adverse events from the Phase 3 breast carcinoma study are described in the ADVERSE REACTIONS section in tabular (Tables 10 and 14) and narrative form.