A Phase II Study Evaluating Orteronel, an Inhibitor of Androgen Biosynthesis, in Patients With Androgen Receptor (AR)-Expressing Metastatic Breast Cancer (MBC).

BACKGROUND: AR is a targetable pathway with AR modulation inhibiting estrogen- and androgen-mediated cell proliferation. Orteronel is an oral, selective, nonsteroidal inhibitor of 17, 20-lyase, a key enzyme in androgen biosynthesis. This study evaluated single-agent orteronel in AR+ metastatic breast cancer (MBC). METHODS: Male/female patients with AR+ MBC were grouped in Cohort 1: AR+ TNBC with l-3 prior chemotherapy regimens or Cohort 2: AR+ HR+ (estrogen [ER+]/ progesterone receptor [PR+] positive) HER2+/- with 1 to 3 prior hormonal and at least 1 prior chemotherapy regimen. Patients with HER2+ MBC must have received at least 2 lines of HER2-targeted therapy. Orteronel was administered at 300 mg BID; response rate was the primary endpoint. RESULTS: Seventy patients were enrolled (Cohort 1, n = 26 and Cohort 2, n = 44). Median treatment duration was 7.1 weeks. Seven patients were on treatment for ≥6 months. One of the 21 evaluated patients in Cohort 1 (4.8%) had an objective response. In Cohort 2, none of the first 23 patients to be evaluated had a response and accrual was stopped. Median progression-free and overall survival were 1.8 and 8.3 months, respectively. Toxicities were predominantly Grade 1 or 2 nausea/vomiting (36%) and fatigue (31%). Grade 3 or 4 events in ≥5% of patients included increased amylase/lipase (10%) and hypertension (6%). CONCLUSIONS: Orteronel demonstrated limited clinical activity in heavily pre-treated AR+ MBC. Further development of orteronel in MBC is not recommended. Further efforts to validate the AR as a therapeutic target should focus on identifying new markers predictive of sensitivity to AR-targeted agents.

Phase II trial of eribulin in patients who do not achieve pathologic complete response (pCR) following neoadjuvant chemotherapy.

PURPOSE: Women with residual invasive breast cancer at the primary site or axillary lymph nodes following neoadjuvant chemotherapy have a high risk of recurrence. Eribulin improves survival in patients with metastatic breast cancer who progress after anthracycline and taxane therapy. This phase 2 trial assessed the efficacy of postoperative eribulin in breast cancer patients who did not achieve a pCR following standard neoadjuvant chemotherapy. METHODS: Women with localized breast cancer who had residual invasive cancer following ≥ 4 cycles of standard anthracycline and/or taxane-containing neoadjuvant chemotherapy received adjuvant eribulin treatment. HER2-positive patients also received trastuzumab for 1 year. Adjuvant hormonal therapy and locoregional radiotherapy were administered as per institutional guidelines. Primary endpoint was the 2-year DFS rate. Three patient cohorts were analyzed: TNBC (Cohort A), HR+/HER2- (Cohort B), and HER2+ (Cohort C). RESULTS: One hundred twenty-six patients (Cohort A-53, Cohort B-42, and Cohort C-31) were enrolled. Neoadjuvant chemotherapy included a taxane and an anthracycline in 70%. Eribulin was well tolerated; 84% of patients received the planned 6 cycles. After a median follow-up of 28 months, the 24-month DFS rates were 56% (95% CI 42, 69), 83% (95% CI 67, 91), and 73% (95% CI 53, 86) for Cohorts A, B, and C, respectively. The most common grade 3/4 treatment-related adverse events were neutropenia (26%), leukopenia (13%), and neuropathy (7%). CONCLUSION: Administration of adjuvant eribulin after neoadjuvant chemotherapy was feasible and well tolerated. The 24-month DFS rate did not reach the study target levels in any of the cohorts and was similar to DFS previously described in these cohorts following neoadjuvant chemotherapy alone.

A Phase II Study of the Combination of Bevacizumab, Pertuzumab, and Octreotide LAR for Patients with Advanced Neuroendocrine Cancers.

PURPOSE: To evaluate efficacy and safety of bevacizumab, pertuzumab, and octreotide depot for advanced neuroendocrine tumors. METHODS: Patients received bevacizumab 15 mg/kg and pertuzumab 420 mg IV q21 days with octreotide depot 30 mg IM q28 days. RESULTS: Toxicities in 43 patients included diarrhea (63%), fatigue (63%), hypertension (44%), and nausea (44%). Reversible G3 hypertension (26%) and LVEF decline (9%) occurred. 7/43 patients achieved objective response (typical carcinoid, 5; pancreatic NET, 2). Median PFS and OS were 6.5 and 26.4 months, respectively. DISCUSSION: Bevacizumab, pertuzumab, and octreotide depot was well-tolerated with a 16% ORR. Results in the well-differentiated carcinoid tumors are thought provoking.

A phase II trial of ixabepilone and cyclophosphamide as neoadjuvant therapy for patients with HER2-negative breast cancer: correlation of pathologic complete response with the 21-gene recurrence score.

Ixabepilone and the taxanes have similar activity in the first-line treatment of metastatic breast cancer, and ixabepilone is sometimes effective in taxane-refractory patients. We conducted a phase 2 trial to evaluate ixabepilone in combination with cyclophosphamide as neoadjuvant treatment for patients with locally advanced HER2-negative breast cancer. Response to neoadjuvant treatment was correlated with the baseline 21-gene Recurrence Score® (Oncotype DX; Genomic Health Inc, Redwood City, CA). Eligible women with HER2-negative locally advanced breast cancer received ixabepilone 40 mg/m(2) plus cyclophosphamide 600 mg/m(2) on day 1 of each 21-day cycle. Following 6 cycles, patients underwent definitive surgery. Primary endpoint was rate of pathologic complete response (pCR). Breast biopsy tumor samples were obtained at pretreatment and at surgery in patients with residual disease. Tumor specimens were analyzed using the 21-gene assay. One hundred sixty-eight patients (median age 52 years; 45 % triple-negative) were enrolled; 161 (96 %) underwent definitive surgery following neoadjuvant ixabepilone/cyclophosphamide. Overall, 27 patients (17 %) achieved pCR, including 19 of 73 (26 %) triple-negative patients. The most frequently occurring grade 3/4 toxicity was neutropenia (98 patients; 58 %). Recurrence Scores were highly correlated with achievement of pCR (0/36 with low or intermediate Recurrence Scores vs. 19/72 with high Recurrence Scores; p = 0.002). There was high concordance between baseline and post-treatment Recurrence Scores in the 72 patients with paired samples. The combination of ixabepilone and cyclophosphamide yielded a pCR rate of 17 %, similar to other neoadjuvant chemotherapy regimens. Pathologic complete responses occurred only in patients with high-risk baseline Recurrence Scores.

Paclitaxel, bevacizumab, and everolimus/placebo as first-line treatment for patients with metastatic HER2-negative breast cancer: a randomized placebo-controlled phase II trial of the Sarah Cannon Research Institute.

Amplified PI3K/Akt/mTOR signaling is common in metastatic breast cancer (MBC). The mTOR inhibitor everolimus improves progression-free survival (PFS) when added to steroidal aromatase inhibitor therapy. This randomized phase II trial compares the efficacy of paclitaxel/bevacizumab/everolimus and paclitaxel/bevacizumab/placebo as first-line treatment for MBC. Patients with untreated HER2-negative MBC were randomized (1:1) to receive 28-day cycles of paclitaxel 90 mg/m(2) IV (days 1, 8, and 15) and bevacizumab 10 mg/kg IV (days 1, 15) with either everolimus 10 mg (Arm 1) or placebo (Arm 2) daily. Treatment continued (evaluation every 8 weeks) until progression or unacceptable toxicity. Treatment of 110 patients allowed detection of an improvement in median PFS from 11 to 16 months (70 % power, α = 0.10). Between August 2009 and June 2011, 113 patients (median age 58 years; 88 % ER or PR positive) were randomized (Arm 1, 56; Arm 2, 57). Patients in both arms received a median of six treatment cycles. Median PFS (95 % CI) was 9.1 months (6.8-18.8) for Arm 1, and 7.1 months (5.6-10.8) for Arm 2 (p = 0.89). Comparisons of other efficacy endpoints were also similar in the two treatment arms. Patients receiving everolimus had more anemia, stomatitis, diarrhea, rash, and arthralgia/myalgia, although the overall incidence of severe (grade 3/4) toxicity was similar. The addition of everolimus did not improve the efficacy of weekly paclitaxel/bevacizumab as first-line treatment for patients with HER2-negative MBC. These results contrast with the demonstrated efficacy of adding everolimus to either hormonal or HER2-targeted therapy in previously treated patients.

Phase I/II trial of neoadjuvant sunitinib administered with weekly paclitaxel/carboplatin in patients with locally advanced triple-negative breast cancer.

The purpose of the study is to evaluate the feasibility and efficacy of adding sunitinib to paclitaxel/carboplatin in the neoadjuvant therapy of patients with triple-negative breast cancer (TNBC). Patients had histologically proven, previously untreated, triple-negative adenocarcinoma, with disease limited to the breast and axilla (clinical T1-T3, N0-N2, M0; T1N1M0 excluded). Following determination of the maximum tolerated doses in the phase I portion, patients in the phase II study received paclitaxel 70 mg/m(2) IV days 1, 8, and 15; carboplatin AUC 5.0 IV day 1; sunitinib 25 mg orally daily; treatment was administered for six 28-day cycles followed by definitive surgery. Sunitinib was resumed postoperatively to complete a 52-week course. Pathologic complete response (pCR) rate was the primary endpoint. Fifty-four patients enrolled; 41 received treatment in the phase II study. Sixteen patients (39 %) were able to complete six cycles of neoadjuvant therapy; 18 additional patients had surgery after completing 2-5 cycles of treatment. The pCR rate in these 34 evaluable patients was 35 %. The toxicity of the regimen was considerable, with myelosuppression resulting in numerous dose reductions and/or omissions of paclitaxel and carboplatin. Eleven patients (27 %) discontinued sunitinib during neoadjuvant therapy, and six patients (14 %) completed 52 weeks of single-agent sunitinib. In the neoadjuvant treatment of patients with TNBC, the combination of paclitaxel, carboplatin, and sunitinib was difficult to administer, and produced a pCR rate comparable to other less toxic regimens. This combination is not recommended for further evaluation. At present, sunitinib has no defined role in the treatment of breast cancer.

Antiemetic guideline consistency and incidence of chemotherapy-induced nausea and vomiting in US community oncology practice: INSPIRE Study.

PURPOSE: Consensus guidelines for preventing chemotherapy-induced nausea and vomiting (CINV) are variably implemented in practice. The purpose of this study was to evaluate the impact of guideline-consistent/guideline-inconsistent CINV prophylaxis (GCCP/GICP) on the incidence of no CINV after cycle 1 of highly or moderately emetogenic chemotherapy (HEC or MEC). PATIENTS AND METHODS: This prospective observational study enrolled chemotherapy-naive adult outpatients who received single-day HEC or MEC at four oncology practice networks, all using electronic health record (EHR) systems, in Georgia, Tennessee, and Florida. Results from the Multinational Association of Supportive Care in Cancer Antiemesis Tool, a validated tool to measure CINV, administered 5 to 8 days postchemotherapy, were merged with EHR data. The primary end point, no CINV, defined as no emesis and no clinically significant nausea (score < 3 on 0-10 scale), was compared between cohorts using logistic regression. RESULTS: A total of 1,295 patients were enrolled (mean age, 59.3 years; 70.0% female; 35.5% HEC). The overall prevalence of GCCP was 57.3%. When corticosteroids were prescribed on days 2 to 4 after all HEC, GCCP for HEC increased from 28.7% to 89.8%; when NK1-receptor antagonists were prescribed after all MEC, GCCP for MEC increased from 73.1% to 97.8%. Over 5 days postchemotherapy, the incidence of no CINV was significantly higher in the GCCP cohort than the GICP cohort (53.4% v 43.8%; P < .001). The adjusted odds of no CINV with GCCP was 1.31 (95% CI, 1.07 to 1.69; P = .037). CONCLUSION: Increased adherence to antiemetic guidelines could significantly reduce the incidence of CINV after HEC and MEC.

Patient perspectives on breast cancer treatment plan and summary documents in community oncology care: a pilot program.

BACKGROUND: Although the routine use of treatment plans and summaries (TPSs) has been recommended to improve the quality of cancer care, limited data exist about their impact on quality, including patient satisfaction and coordination of care. METHODS: Patients received TPSs as part of the American Society of Clinical Oncology Breast Cancer Registry (BCR) pilot program of 20 community oncology practices. Participants were surveyed 2 to 4 weeks after receiving a TPS to evaluate their perceptions of the document. Patients who were receiving chemotherapy received the TPS as separate plan and summary documents (at the start and the end of treatment) and could complete 2 surveys. Others received a single integrated TPS. Eligible survey participants had stage 0 through III breast cancer and were enrolled in the BCR. RESULTS: Of 292 consented patients, 174 (60%) completed at least 1 survey. Of 157 patients who recalled receiving a TPS, 148 (94%) believed that the documents improved patient-physician communication, and 128 (82%) believed that they improved communication between physicians; 113 (72%) said the documents increased their peace of mind, whereas 2 (1%) had less peace of mind. Of 152 patients (97%) who still had their documents, 147 (97%) said they were useful, and 94 (62%) had given or planned to give the documents to another physician. All 63 patients who were surveyed after receiving a summary recommended that practices continue to provide TPSs to patients. CONCLUSIONS: Participants in this study expressed high satisfaction with TPSs. Additional research is needed to study the broad-scale implementation of the BCR and to evaluate the impact of routine use of TPSs on the quality of care delivered.

Phase 1 results from a study of romidepsin in combination with gemcitabine in patients with advanced solid tumors.

Romidepsin is a potent histone deacetylase inhibitor; preclinical studies showed potential synergy with the nucleoside analog gemcitabine. This phase 1 trial was conducted to determine the maximum tolerated dose for two schedules of romidepsin plus gemcitabine in patients with advanced solid tumors in which gemcitabine had previously demonstrated clinical activity. The recommended phase 2 dose was 12 mg/m(2) romidepsin plus 800 mg/m(2) gemcitabine on days 1 and 15 every 28 days. Results suggest additive hematologic toxicities of romidepsin plus gemcitabine, but the level of antitumor activity observed warrants more formal trials of this combination to further assess safety and efficacy.

A pilot study of adjuvant doxorubicin and cyclophosphamide followed by paclitaxel and sorafenib in women with node-positive or high-risk early-stage breast cancer.

PURPOSE: To examine the safety of sorafenib combined with standard adjuvant treatment in patients with node-positive or otherwise high-risk breast cancer. PATIENTS AND METHODS: Eligibility: mastectomy/breast-conserving surgery; axillary node assessment for stage I/II/IIIA/IIIC (T1-3, N3a only) breast cancer; node-positive/high-risk node-negative (tumor size >2 cm; hormone-receptor negative; grade 2/3; or age <35 years); Eastern Cooperative Oncology Group performance status (ECOG-PS) 0-1; and adequate organ function. TREATMENT: doxorubicin (60 mg/m(2) intravenous) and cyclophosphamide (600 mg/m(2) intravenous; AC) on day 1, every 3 weeks (x 4 cycles), followed by paclitaxel 175 mg/m(2) intravenous on day 1, (every 3 weeks x 4 cycles) or 80 mg/m(2) intravenous (every week/x 12 cycles), combined with sorafenib (400 mg oral twice a week; TS) for 12 months or less. RESULTS: Forty-five patients were enrolled from 5/07-1/08. Baseline characteristics included: median age of 54 years (range, 35-74 years); 93% of patients with ECOG-PS 0; 84% node-positive; 33% hormone-receptor negative. All patients completed AC treatment and were eligible to receive TS; of these, 8 (13%) patients came off study due to physician/patient decision; 21 (47%) patients came off study due to toxicity; 2 (4%) patients completed TS but did not proceed with maintenance sorafenib; and 14 (31%) patients completed TS and entered the maintenance phase of sorafenib treatment. Sorafenib was taken for 6.1 weeks during the paclitaxel phase and 15 weeks during maintenance. Severe toxicities during sorafenib therapy were limited, including neutropenia, anorexia, arthralgia, diarrhea, and dyspnea. After a median follow-up of 21.0 months (range, 18.9-25.9), all patients were alive and without recurrence. CONCLUSION: Sorafenib was generally associated with limited severe toxicity when combined with paclitaxel following AC. However, many patients discontinued sorafenib early due to grade 1/2 toxicity, physician/patient decision, and treatment compliance. Additional studies of sorafenib in breast cancer in the neoadjuvant and triple-negative settings are warranted.

A pilot study of adjuvant nanoparticle albumin-bound (nab) paclitaxel and cyclophosphamide, with trastuzumab in HER2-positive patients, in the treatment of early-stage breast cancer.

nab-Paclitaxel has shown favorable efficacy and toxicity profiles compared to other taxanes in the treatment of metastatic breast cancer. In this pilot trial, we evaluated a nab-paclitaxel-containing adjuvant regimen in patients with early stage breast cancer. Patients with node-positive or high-risk node-negative early-stage breast cancer were eligible following completion of standard primary therapy. All the patients received four cycles, at 21-day intervals, of nab-paclitaxel (100 mg/m(2) IV days 1, 8, and 15) and cyclophosphamide (600 mg/m(2) IV day 1). HER2-positive patients also received trastuzumab 8 mg/kg IV on cycle 1 day 1, followed by 6 mg/kg every 21 days for a total of 52 weeks. The purpose of this trial was to evaluate feasibility and toxicity of this nab-paclitaxel-containing adjuvant regimen. 62 patients were treated between 2/08 and 11/08. The majority of the patients (87%) were HER2-negative. This adjuvant regimen was well tolerated, and full doses of all agents were administered in >90% of cycles. Grade 3/4 neutropenia occurred in 53% of the patients; however, only one episode of febrile neutropenia occurred in a total of 249 cycles administered. Other grade 3/4 adverse events occurred in less than 5% of patients. After short follow-up, all the patients remain alive and disease-free. The combination of nab-paclitaxel and cyclophosphamide, with or without trastuzumab, is feasible and well tolerated in patients with early stage breast cancer. Further investigation of the role of nab-paclitaxel in adjuvant breast cancer therapy is indicated, but definitive evaluation will require randomized phase III trials.

A phase II trial of neoadjuvant gemcitabine, epirubicin, and docetaxel as primary treatment of patients with locally advanced or inflammatory breast cancer.

BACKGROUND: Three-drug regimens containing gemcitabine, an anthracycline, and a taxane produce response rates of 70%-90% in patients with metastatic breast cancer (MBC) although accompanied by considerable hematologic toxicity. We explored the combination of gemcitabine/epirubicin/docetaxel as neoadjuvant therapy. Docetaxel was administered weekly to decrease myelosuppression. PATIENTS AND METHODS: A total of 110 patients with locally advanced or inflammatory breast cancer received neoadjuvant gemcitabine 800 mg/m2 intravenously (I.V.) days 1 and 8, epirubicin 75 mg/m2 I.V. day 1, and docetaxel 30 mg/m2 I.V. days 1 and 8, repeated every 21 days for 4 cycles. Then patients had either mastectomy or breast conservation surgery, and pathologic treatment responses were assessed. After surgery, 4 cycles of adjuvant gemcitabine 1000 mg/m2 I.V. days 1 and 8 and docetaxel 35 mg/m2 I.V. days 1 and 8 were administered at 21-day intervals. After patients completed chemotherapy, locoregional radiation therapy and/or anti-estrogen therapy was administered per standard guidelines. RESULTS: Treatment with 4 cycles of neoadjuvant gemcitabine, epirubicin, and weekly docetaxel resulted in an objective response in 79 of 110 patients enrolled (72%; 95% CI, 63-80%). Twenty of 103 patients (19%) who had surgery had pathologic complete response (pCR). Moderate hematologic toxicity was evident during neoadjuvant therapy, with grade 3/4 neutropenia in 41% and febrile neutropenia in 11% of the patients. Protocol-specified dose modifications were required in 35% of the patients, and 58% of the patients used myeloid growth factors. CONCLUSION: The pCR rate of 19% achieved with gemcitabine, epirubicin, and weekly docetaxel confirms previous reports with similar 3-drug regimens. The use of a weekly schedule of docetaxel did not appear to reduce the incidence of grade 3/4 hematologic toxicity.

Tracheoesophageal fistula formation in patients with lung cancer treated with chemoradiation and bevacizumab.

PURPOSE Tracheoesophageal fistulae are rare complications of thoracic cancers and their treatments. Novel antiangiogenic agents in cancer treatment such as bevacizumab potentially impact wound healing and may contribute to tracheoesophageal fistula development. PATIENTS AND METHODS We conducted two independent phase II clinical trials in small-cell lung cancer and non-small-cell lung cancer using bevacizumab in combination with chemotherapy and radiation. Both trials were intended to assess preliminary efficacy and safety outcomes. Results For the limited-stage small-cell lung cancer trial, 29 patients were enrolled beginning April 2006, and closed early due to toxicity in March 2007 (14-month median follow-up). The locally advanced, non-small-cell lung cancer trial opened with enrollment limited to five patients in February 2007, and closed early due to safety in December 2007. In each trial, we observed tracheoesophageal fistulae development and related morbidity and mortality, prompting early trial closures, US Food and Drug Administration warnings, and a change in bevacizumab labeling. CONCLUSION The current data from the final reports from these two trials suggest bevacizumab and chemoradiotherapy are associated with a relatively high incidence of tracheoesophageal fistulae formation in both small-cell lung cancer and non-small-cell lung cancer settings. Strategies to safely incorporate novel antiangiogenic agents into combined-modality therapy in lung cancer are needed.

A phase II feasibility trial of dose-dense docetaxel followed by doxorubicin/cyclophosphamide as adjuvant or neoadjuvant treatment for women with node-positive or high-risk node-negative breast cancer.

PURPOSE: Dose-dense adjuvant chemotherapy with doxorubicin/cyclophosphamide (AC) followed by paclitaxel has improved results compared with standard dosing at 3-week intervals. Because docetaxel might be more active than paclitaxel in the treatment of metastatic breast cancer, we explored the feasibility of substituting docetaxel for paclitaxel in dose-dense adjuvant therapy. PATIENTS AND METHODS: Seventy-six patients with node-positive breast cancer received treatment with 4 cycles of docetaxel followed by 4 cycles of AC administered with pegfilgrastim at 2-week intervals. When treatment proved difficult for the first 33 patients, 2 additional cohorts were treated: first, with a reduction of pegfilgrastim and dexamethasone prophylaxis doses (cohort 2) and then with a reduction of docetaxel from 100 mg/m2 to 75 mg/m2 (cohort 3). RESULTS: Treatment with dose-dense docetaxel at 100 mg/m2 resulted in unacceptable toxicity (24% of patients required hospitalization) and compromised subsequent dosing of AC as a result of neutropenia on the day of scheduled treatment. Only 21 patients (40%) who received docetaxel 100 mg/m2 were able to receive all 8 doses at full dose and on schedule. Reduction of docetaxel to 75 mg/m2 allowed 74% of patients to receive all 8 doses as scheduled. Delivery of AC as scheduled occurred in 82% of patients who received docetaxel 75 mg/m2 versus 40% when docetaxel 100 mg/m2 was administered. CONCLUSION: Full-dose docetaxel is difficult to administer as part of this dose-dense treatment regimen. Docetaxel 75 mg/m2 can be administered with improved subsequent delivery of 4 courses of dose-dense AC. Until comparative clinical studies are available, docetaxel should not be substituted for paclitaxel in dose-dense adjuvant chemotherapy for patients with high-risk breast cancer.

Phase I dose escalation and pharmacokinetic study of lapatinib in combination with trastuzumab in patients with advanced ErbB2-positive breast cancer.

PURPOSE: The combination of lapatinib and trastuzumab has been observed to have a synergistic, antiproliferative effect against ErbB2-positive breast cancer cells in vitro. This phase I study assessed the safety, clinical feasibility, optimally tolerated regimen (OTR), pharmacokinetics (PK), and preliminary clinical activity of this combination in patients with ErbB2-positive advanced breast cancer. PATIENTS AND METHODS: Cohorts of three patients with ErbB2-positive advanced breast cancer were treated with escalating doses of lapatinib (750 to 1,500 mg) administered once daily (continuous) in combination with trastuzumab (4 mg/kg loading dose then 2 mg/kg weekly) to determine the OTR. Once the OTR was determined, additional patients were enrolled to provide the PK profile of both agents alone and in combination. RESULTS: A total of 54 patients were treated: 27 in the dose-escalation group and 27 in the PK group. Overall, adverse events were mild to moderate in severity, with no drug-related grade 4 events. The most frequent drug-related grade 3 events included diarrhea (17%), fatigue (11%), and rash (6%). The OTR was 1,000 mg lapatinib with standard weekly trastuzumab. One patient had a complete response and seven patients had partial responses. The PK parameters (maximum concentration in plasma and area under the curve) of lapatinib and trastuzumab in combination were not significantly different than when either was administered alone. CONCLUSION: The OTR of the lapatinib/trastuzumab combination was lapatinib 1,000 mg per day with standard weekly trastuzumab. At these doses, the regimen was well tolerated and clinically active in this heavily pretreated ErbB2-positive breast cancer population.