Ian E. Krop

Trastuzumab Emtansine for HER2-Positive Advanced Breast Cancer

BACKGROUND Trastuzumab emtansine (T-DM1) is an antibody-drug conjugate incorporating the human epidermal growth factor receptor 2 (HER2)-targeted antitumor properties of trastuzumab with the cytotoxic activity of the microtubule-inhibitory agent DM1. The antibody and the cytotoxic agent are conjugated by means of a stable linker. METHODS We randomly assigned patients with HER2-positive advanced breast cancer, who had previously been treated with trastuzumab and a taxane, to T-DM1 or lapatinib plus capecitabine. The primary end points were progression-free survival (as assessed by independent review), overall survival, and safety. Secondary end points included progression-free survival (investigator-assessed), the objective response rate, and the time to symptom progression. Two interim analyses of overall survival were conducted. RESULTS Among 991 randomly assigned patients, median progression-free survival as assessed by independent review was 9.6 months with T-DM1 versus 6.4 months with lapatinib plus capecitabine (hazard ratio for progression or death from any cause, 0.65; 95% confidence interval [CI], 0.55 to 0.77; P<0.001), and median overall survival at the second interim analysis crossed the stopping boundary for efficacy (30.9 months vs. 25.1 months; hazard ratio for death from any cause, 0.68; 95% CI, 0.55 to 0.85; P<0.001). The objective response rate was higher with T-DM1 (43.6%, vs. 30.8% with lapatinib plus capecitabine; P<0.001); results for all additional secondary end points favored T-DM1. Rates of grade 3 or 4 adverse events were higher with lapatinib plus capecitabine than with T-DM1 (57% vs. 41%). The incidences of thrombocytopenia and increased serum aminotransferase levels were higher with T-DM1, whereas the incidences of diarrhea, nausea, vomiting, and palmar-plantar erythrodysesthesia were higher with lapatinib plus capecitabine. CONCLUSIONS T-DM1 significantly prolonged progression-free and overall survival with less toxicity than lapatinib plus capecitabine in patients with HER2-positive advanced breast cancer previously treated with trastuzumab and a taxane. (Funded by F. Hoffmann-La Roche/Genentech; EMILIA ClinicalTrials.gov number, NCT00829166.).

E2A proteins are required for proper B cell development and initiation of immunoglobulin gene rearrangements

E12 and E47 are two helix-loop-helix transcription factors that arise by alternative splicing of the E2A gene. Both have been implicated in the regulation of immunoglobulin gene expression. We have now generated E2A (-/-) mice by gene targeting. E2A-null mutant mice fail to generate mature B cells. The arrest of B cell development occurs at an early stage, since no immunoglobulin DJ rearrangements can be detected in homozygous mutant mice. While immunoglobulin germline I mu RAG-1, mb-1, CD19, and lambda 5 transcripts are dramatically reduced in fetal livers of E2A (-/-) mice, B29 and mu degrees transcripts are present, but at lower levels. In addition, we show that Pax-5 transcripts are significantly reduced in fetal livers of E2A (-/-) mice. These data suggest a crucial role for E2A products as central regulators in early B cell differentiation.

Phase II Study of the Antibody Drug Conjugate Trastuzumab-DM1 for the Treatment of Human Epidermal Growth Factor Receptor 2 (HER2) –Positive Breast Cancer After Prior HER2-Directed Therapy

PURPOSE The antibody-drug conjugate trastuzumab-DM1 (T-DM1) combines the biologic activity of trastuzumab with targeted delivery of a potent antimicrotubule agent, DM1, to human epidermal growth factor receptor 2 (HER2)-overexpressing cancer cells. Based on results from a phase I study that showed T-DM1 was well tolerated at the maximum-tolerated dose of 3.6 mg/kg every 3 weeks, with evidence of efficacy, in patients with HER2-positive metastatic breast cancer (MBC) who were previously treated with trastuzumab, we conducted a phase II study to further define the safety and efficacy of T-DM1 in this patient population. PATIENTS AND METHODS This report describes a single-arm phase II study (TDM4258g) that assessed efficacy and safety of intravenous T-DM1 (3.6 mg/kg every 3 weeks) in patients with HER2-positive MBC who had tumor progression after prior treatment with HER2-directed therapy and who had received prior chemotherapy. RESULTS With a follow-up of ≥ 12 months among 112 treated patients, the objective response rate by independent assessment was 25.9% (95% CI, 18.4% to 34.4%). Median duration of response was not reached as a result of insufficient events (lower limit of 95% CI, 6.2 months), and median progression-free survival time was 4.6 months (95% CI, 3.9 to 8.6 months). The response rates were higher among patients with confirmed HER2-positive tumors (immunohistochemistry 3+ or fluorescent in situ hybridization positive) by retrospective central testing (n = 74). Higher response rates were also observed in patients whose tumors expressed ≥ median HER2 levels by quantitative reverse transcriptase polymerase chain reaction for HER2 expression, compared with patients who had less than median HER2 levels. T-DM1 was well tolerated with no dose-limiting cardiotoxicity. Most adverse events (AEs) were grade 1 or 2; the most frequent grade ≥ 3 AEs were hypokalemia (8.9%), thrombocytopenia (8.0%), and fatigue (4.5%). CONCLUSION T-DM1 has robust single-agent activity in patients with heavily pretreated, HER2-positive MBC and is well tolerated at the recommended phase II dose.

Phase I Study of Trastuzumab-DM1, an HER2 Antibody-Drug Conjugate, Given Every 3 Weeks to Patients With HER2-Positive Metastatic Breast Cancer

PURPOSE Trastuzumab-DM1 (T-DM1) is an antibody-drug conjugate that uses trastuzumab to specifically deliver the maytansinoid antimicrotubule agent DM1 to HER2-positive cells. This first-in-human study of T-DM1 evaluated safety, pharmacokinetics, and preliminary activity of T-DM1 in patients with advanced HER2-positive breast cancer. PATIENTS AND METHODS Successive cohorts of patients who had progressed on trastuzumab-based therapy received escalating doses of T-DM1. Outcomes were assessed by standard solid-tumor phase I methods. RESULTS Twenty-four patients who had received a median of four prior chemotherapeutic agents for metastatic disease received T-DM1 at 0.3 mg/kg to 4.8 mg/kg on an every-3-weeks schedule. Transient thrombocytopenia was dose-limiting at 4.8 mg/kg; the maximum-tolerated dose (MTD) was 3.6 mg/kg. The half-life of T-DM1 at the MTD was 3.5 days, with peak DM1 levels < 10 ng/mL. Clearance at doses < 1.2 mg/kg was faster than at higher doses. Common drug-related adverse events (AEs) included grade < or = 2 thrombocytopenia, elevated transaminases, fatigue, nausea, and anemia. No grade > 1 nausea, vomiting, alopecia, or neuropathy events and no cardiac effects requiring dose modification were reported. The clinical benefit rate (objective response plus stable disease at 6 months) among 15 patients treated at the MTD was 73%, including five objective responses. The confirmed response rate in patients with measurable disease at the MTD (n = 9) was 44%. CONCLUSION At the MTD of 3.6 mg/kg every 3 weeks, T-DM1 was associated with mild, reversible toxicity and substantial clinical activity in a heavily pretreated population. Phase II and III trials in patients with advanced HER2-positive breast cancer are under way.

ESO-ESMO 2nd international consensus guidelines for advanced breast cancer (ABC2)†

Advanced Breast Cancer (ABC) is a treatable but still generally incurable disease. The goals of care are to optimize both length and quality of life. Due to continuous research, several advances have been made, particularly for the HER-2-positive and for Luminal-like subtypes. Notwithstanding these advances, median overall survival of patients with ABC is still only 2–3 years, although the range is wide [1–5], and survival may be longer for patients treated in specialized institutions [6]. Implementation of current knowledge is highly variable among countries and within each country.

Trastuzumab emtansine versus treatment of physician's choice for pretreated HER2-positive advanced breast cancer (TH3RESA): a randomised, open-label, phase 3 trial

BACKGROUND Patients with progressive disease after two or more HER2-directed regimens for recurrent or metastatic breast cancer have few effective therapeutic options. We aimed to compare trastuzumab emtansine, an antibody-drug conjugate comprising the cytotoxic agent DM1 linked to trastuzumab, with treatment of physicians choice in this population of patients. METHODS This randomised, open-label, phase 3 trial took place in medical centres in 22 countries across Europe, North America, South America, and Asia-Pacific. Eligible patients (≥18 years, left ventricular ejection fraction ≥50%, Eastern Cooperative Oncology Group performance status 0-2) with progressive HER2-positive advanced breast cancer who had received two or more HER2-directed regimens in the advanced setting, including trastuzumab and lapatinib, and previous taxane therapy in any setting, were randomly assigned (in a 2:1 ratio) to trastuzumab emtansine (3·6 mg/kg intravenously every 21 days) or physicians choice using a permuted block randomisation scheme by an interactive voice and web response system. Patients were stratified according to world region (USA vs western Europe vs other), number of previous regimens (excluding single-agent hormonal therapy) for the treatment of advanced disease (two to three vs more than three), and presence of visceral disease (any vs none). Coprimary endpoints were investigator-assessed progression-free survival (PFS) and overall survival in the intention-to-treat population. We report the final PFS analysis and the first interim overall survival analysis. This study is registered with ClinicalTrials.gov, number NCT01419197. FINDINGS From Sept 14, 2011, to Nov 19, 2012, 602 patients were randomly assigned (404 to trastuzumab emtansine and 198 to physicians choice). At data cutoff (Feb 11, 2013), 44 patients assigned to physicians choice had crossed over to trastuzumab emtansine. After a median follow-up of 7·2 months (IQR 5·0-10·1 months) in the trastuzumab emtansine group and 6·5 months (IQR 4·1-9·7) in the physicians choice group, 219 (54%) patients in the trastuzumab emtansine group and 129 (65%) of patients in the physicians choice group had PFS events. PFS was significantly improved with trastuzumab emtansine compared with physicians choice (median 6·2 months [95% CI 5·59-6·87] vs 3·3 months [2·89-4·14]; stratified hazard ratio [HR] 0·528 [0·422-0·661]; p<0·0001). Interim overall survival analysis showed a trend favouring trastuzumab emtansine (stratified HR 0·552 [95% CI 0·369-0·826]; p=0·0034), but the stopping boundary was not crossed. A lower incidence of grade 3 or worse adverse events was reported with trastuzumab emtansine than with physicians choice (130 events [32%] in 403 patients vs 80 events [43%] in 184 patients). Neutropenia (ten [2%] vs 29 [16%]), diarrhoea (three [<1%] vs eight [4%]), and febrile neutropenia (one [<1%] vs seven [4%]) were grade 3 or worse adverse events that were more common in the physicians choice group than in the trastuzumab emtansine group. Thrombocytopenia (19 [5%] vs three [2%]) was the grade 3 or worse adverse event that was more common in the trastuzumab emtansine group. 74 (18%) patients in the trastuzumab emtansine group and 38 (21%) in the physicians choice group reported a serious adverse event. INTERPRETATION Trastuzumab emtansine should be considered as a new standard for patients with HER2-positive advanced breast cancer who have previously received trastuzumab and lapatinib. FUNDING Genentech.

A Phase II Study of Trastuzumab Emtansine in Patients With Human Epidermal Growth Factor Receptor 2–Positive Metastatic Breast Cancer Who Were Previously Treated With Trastuzumab, Lapatinib, an Anthracycline, a Taxane, and Capecitabine

PURPOSE To determine whether the antibody-drug conjugate trastuzumab emtansine (T-DM1), which combines human epidermal growth factor receptor 2 (HER2) -targeted delivery of the potent antimicrotubule agent DM1 with the antitumor activity of trastuzumab, is effective in patients with HER2-positive metastatic breast cancer (MBC) who have previously received all standard HER2-directed therapies. PATIENTS AND METHODS In this single-arm phase II study, T-DM1 3.6 mg/kg was administered intravenously every 3 weeks to patients with HER2-positive MBC who had prior treatment with trastuzumab, lapatinib, an anthracycline, a taxane, and capecitabine. The primary objectives were overall response rate (ORR) by independent review and safety. RESULTS Among 110 pretreated patients (median, seven prior agents for MBC; median follow-up, 17.4 months), the ORR was 34.5% (95% CI, 26.1% to 43.9%), clinical benefit rate was 48.2% (95% CI, 38.8% to 57.9%), median progression-free survival (PFS) was 6.9 months (95% CI, 4.2 to 8.4 months), and median duration of response was 7.2 months (95% CI, 4.6 months to not estimable). In patients with confirmed HER2-positive tumors (n = 80 by retrospective central testing), the response rate was 41.3% (95% CI, 30.4% to 52.8%), and median PFS was 7.3 months (95% CI, 4.6 to 12.3 months). Most adverse events were grades 1 to 2; the most frequent grade ≥ 3 events were thrombocytopenia (9.1%), fatigue (4.5%), and cellulitis (3.6%). CONCLUSION T-DM1 is well tolerated and has single-agent activity in patients with HER2-positive MBC who have previously received both approved HER2-directed therapies and multiple chemotherapy agents. T-DM1 may be an effective new treatment for this patient population.

Adjuvant Paclitaxel and Trastuzumab for Node-Negative, HER2-Positive Breast Cancer

BACKGROUND No single standard treatment exists for patients with small, node-negative, human epidermal growth factor receptor type 2 (HER2)-positive breast cancers, because most of these patients have been ineligible for the pivotal trials of adjuvant trastuzumab. METHODS We performed an uncontrolled, single-group, multicenter, investigator-initiated study of adjuvant paclitaxel and trastuzumab in 406 patients with tumors measuring up to 3 cm in greatest dimension. Patients received weekly treatment with paclitaxel and trastuzumab for 12 weeks, followed by 9 months of trastuzumab monotherapy. The primary end point was survival free from invasive disease. RESULTS The median follow-up period was 4.0 years. The 3-year rate of survival free from invasive disease was 98.7% (95% confidence interval [CI], 97.6 to 99.8). Among the 12 relapses seen, 2 were due to distant metastatic breast cancer. Excluding contralateral HER2-negative breast cancers and nonbreast cancers, 7 disease-specific events were noted. A total of 13 patients (3.2%; 95% CI, 1.7 to 5.4) reported at least one episode of grade 3 neuropathy, and 2 had symptomatic congestive heart failure (0.5%; 95% CI, 0.1 to 1.8), both of whom had normalization of the left ventricular ejection fraction after discontinuation of trastuzumab. A total of 13 patients had significant asymptomatic declines in ejection fraction (3.2%; 95% CI, 1.7 to 5.4), as defined by the study, but 11 of these patients were able to resume trastuzumab therapy after a brief interruption. CONCLUSIONS Among women with predominantly stage I HER2-positive breast cancer, treatment with adjuvant paclitaxel plus trastuzumab was associated with a risk of early recurrence of about 2%; 6% of patients withdrew from the study because of protocol-specified adverse events. (Funded by Genentech; ClinicalTrials.gov number, NCT00542451.).

1st International consensus guidelines for advanced breast cancer (ABC 1)

The 1st international Consensus Conference for Advanced Breast Cancer (ABC 1) took place on November 2011, in Lisbon. Consensus guidelines for the management of this disease were developed. This manuscript summarizes these international consensus guidelines.

Phase I/II Study of Trastuzumab in Combination With Everolimus (RAD001) in Patients With HER2-Overexpressing Metastatic Breast Cancer Who Progressed on Trastuzumab-Based Therapy

PURPOSE Trastuzumab resistance has been linked to activation of the phosphoinositol 3-kinase (PI3K) pathway. Phosphatase and tensin homolog (PTEN) is a dual phosphatase that counteracts the PI3K function; PTEN loss leads to activation of the Akt cascade and the downstream mammalian target of rapamycin (mTOR). Preclinical studies demonstrated that mTOR inhibition sensitized the response to trastuzumab in mice with HER2 overexpressing and PTEN-deficient breast xenografts. Our trial evaluated the safety and efficacy of the combination of everolimus and trastuzumab in women with HER2-overexpressing metastatic breast cancer (MBC) that progressed on trastuzumab-based therapy. PATIENTS AND METHODS This represents a pooled analysis (n = 47), stemming from two trials that occurred concurrently in The University of Texas MD Anderson Cancer Center, Beth Israel Deaconess Medical Center, and Dana-Farber Cancer Institute. Patients with HER2-overexpressing MBC who had progressed on trastuzumab-based therapy received trastuzumab every 3 weeks in combination with daily everolimus. RESULTS Among 47 patients, the combination of everolimus and trastuzumab provided partial responses in seven patients (15%) and persistent stable disease (lasting 6 months or longer) in nine patients (19%), resulting in a clinical benefit rate of 34%. The median progression-free survival (PFS) was 4.1 month. Fatigue, infection, and mucositis were the predominant nonhematologic toxicities. Trastuzumab did not have significant influence on the pharmacokinetic profile of everolimus. Patients with PTEN loss demonstrated decreased overall survival (P = .048). However, PFS was not affected by PTEN loss. CONCLUSION Inhibition of mTOR results in clinical benefit and disease response in patients with trastuzumab-resistant HER2-overexpressing MBC.