Predicting Thrombocytopenia in Patients With Breast Cancer Treated With Ado-trastuzumab Emtansine

IntroductionThrombocytopenia is a common and potentially serious adverse event of ado-trastuzumab emtansine (T-DM1) use in patients with advanced breast cancer. However, the risk factors have been minimally explored. Our aim was to develop a clinical prediction model from the clinicopathologic data that would allow for quantification of the personalized risks of thrombocytopenia from T-DM1 usage.Materials and MethodsData from 3 clinical trials, EMILIA (a study of trastuzumab emtansine versus capecitabine + lapatinib in participants with HER2 [human epidermal growth factor receptor 2]-positive locally advanced or metastatic breast cancer), TH3RESA (a study of trastuzumab emtansine in comparison with treatment of physician's choice in participants with HER2-positive breast cancer who have received at least two prior regimens of HER2-directed therapy), and MARIANNE [a study of trastuzumab emtansine (T-DM1) plus pertuzumab/pertuzumab placebo versus trastuzumab (Herceptin) plus a taxane in participants with metastatic breast cancer], were pooled. Cox proportional hazard analysis was used to assess the association between the pretreatment clinicopathologic data and grade ≥ 3 thrombocytopenia occurring within the first 365 days of T-DM1 use. A multivariable clinical prediction model was developed using a backward elimination process.ResultsOf the 1620 participants, 141 (9%) had experienced grade ≥ 3 thrombocytopenia. On univariable analysis, the body mass index, race, presence of brain metastasis, platelet count, white blood cell count, and concomitant corticosteroid use were significantly associated with the occurrence of grade ≥ 3 thrombocytopenia (P < .05). The multivariable prediction model was optimally defined by race (Asian vs. non-Asian) and platelet count (100-220 vs. 220-300 vs. >300 × 10⁹/L). A large discrimination between the prognostic subgroups was observed. The highest risk subgroup (Asian and platelet count of 100-220 cells ×10⁹/L) had a 40% probability of grade ≥ 3 thrombocytopenia within the first 365 days of T-DM1 therapy compared with 2% for the lowest risk subgroup (non-Asian and platelet count > 300 × 10⁹/L).ConclusionA clinical prediction model, defined by race and pretreatment platelet count, was able to discriminate subgroups with a significantly different risk of grade ≥ 3 thrombocytopenia after T-DM1 initiation. The model allows for improved interpretation of the personalized risks and risk/benefit ratio of T-DM1.     

Safety and efficacy study of oral metronomic vinorelbine combined with trastuzumab (mNH) in HER2-positive metastatic breast cancer: a phase II trial

Purpose

We conducted a single-arm prospective phase II trial to evaluate the efficacy and safety of oral metronomic vinorelbine combined with trastuzumab (mNH) in human epidermal growth factor receptor 2-positive (HER2-positive) metastatic breast cancer (MBC) patients.

Methods

HER2-positive MBC patients received oral vinorelbine 40 mg thrice a week and trastuzumab (loading dose of 8 mg/kg, followed by 6 mg/kg every 3 weeks) until disease progression, unacceptable toxicity, or consent withdrawal. The primary endpoints were objective response rate (ORR), clinical benefit rate (CBR; CR?+?PR?+?SD for?≥?24 weeks). The secondary endpoints were progression-free survival (PFS), tolerability, and overall survival (OS).

Results

Twenty patients with HER2-positive MBC were enrolled, with a median of 1 prior chemotherapy regimens for MBC. Median age was 61.5 years (95% Confidence Interval (CI) 48.6–63.1). Visceral involvements presented in 14 patients (70.0%). ORR was 20.0%, and CBR was 75% with 4 PR (20.0%) and 11 SD (55.0%). The median PFS (mPFS) and median OS (mOS) were 7.4 months (95% CI 3.2–11.5) and 45.8 months (95%CI: not reached), respectively. The mPFS was 17.7 months (95%CI not reached) and 5.8 months (95%CI 5.6–5.9) in mNH as first-line and?≥?second-line therapy (log rank p?=?0.03), respectively. The most common grade 1 adverse events (AEs) included nausea (15%), leukopenia (15%), ALT/AST elevation (15%), diarrhea (10%), and peripheral neuropathy (10%). Grade 2 adverse events included leukopenia (5%) and neutropenia (10%). No grade 3/4 AEs were observed.

Conclusions

Oral metronomic vinorelbine combined with trastuzumab is a well-tolerated and effective anti-tumor regimen for HER2-positive MBC.

     

Incidence and Management of Diarrhea With Adjuvant Pertuzumab and Trastuzumab in Patients With Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer

BackgroundThe APHINITY (BIG 4-11) study showed that pertuzumab significantly improved the rates of invasive disease-free survival among patients with human epidermal growth factor receptor 2 (HER2)-positive, operable breast cancer when added to adjuvant trastuzumab and chemotherapy. Because diarrhea was a common adverse event that could compromise treatment administration, we evaluated the incidence and management of diarrhea in the APHINITY study.Patients and MethodsThe APHINITY trial is a prospective, randomized, multicenter, multinational, double-blind, placebo-controlled trial. The eligible patients were randomly assigned to receive standard adjuvant chemotherapy and 1 year of trastuzumab combined with pertuzumab or placebo. The diarrhea incidence, severity (National Cancer Institute common terminology criteria for adverse events, version 4.0), onset, and management were analyzed.ResultsA total of 4805 patients were randomized. Diarrhea of any grade was the most common adverse event and occurred in 71% of patients in the pertuzumab arm versus 45% in the placebo arm. Diarrhea grade 3 to 4 was observed in 10% and 4% in the pertuzumab and placebo arms, respectively. The greatest incidence of diarrhea was reported during the concomitant administration of HER2-targeted therapy and taxane (61% vs. 34% of patients experienced an event with pertuzumab vs. placebo, respectively). A marked decrease was observed on chemotherapy cessation. Antidiarrheal agents were commonly used, and diarrhea rarely caused treatment dose modifications or discontinuation.ConclusionDiarrhea was a common adverse event in the APHINITY study. Most episodes were low grade and were generally manageable with common antidiarrheal agents. The incidence of diarrhea was greater with the combination of a taxane and HER2-targeted treatment and decreased once chemotherapy was stopped.     

Cardiac assessment in Australian patients receiving (neo)adjuvant trastuzumab for HER2-positive early breast cancer: a population-based study

Purpose

Cardiac function assessment is important for detecting and managing trastuzumab-associated cardiotoxicity. Our study estimates rates and predictors of cardiac assessment among patients receiving trastuzumab for HER2-positive early breast cancer (HER2+EBC) in Australia.

Methods

We conducted a retrospective cohort study of Australians initiating (neo)adjuvant trastuzumab for HER2+EBC between 1 January 2015 and 15 April 2019. We used administrative claims to determine the number of patients receiving guideline-recommended assessment, i.e. evidence of baseline cardiac assessment (between 120 days before and 30 days after trastuzumab initiation) and regular on-treatment cardiac assessments (at least every 120 days). We examined factors associated with baseline and regular on-treatment cardiac assessment.

Results

Our study includes 5621 patients (median age 56 years), of whom 4984 (88.7%) had a baseline cardiac function test. Among 4280 patients with at least 12 months of follow-up, 2702 (63.1%) had guideline-recommended cardiac assessment. Rates of guideline-recommended assessment increased with later year of diagnosis (60.9% in 2015 vs 68.3% in 2018, OR 1.34, 95% CI 1.06–1.69). Patients with higher baseline comorbidities and greater socioeconomic disadvantage were less likely to have guideline-recommended cardiac assessment. Cardiac assessment practices varied by State/Territory. There was no association between baseline cardiac risk or anthracycline use and the likelihood of receiving guideline-recommended cardiac assessment.

Conclusion

The majority of patients receiving (neo)adjuvant trastuzumab had guideline-recommended baseline and on-treatment cardiac assessment. Variations in cardiac assessment predominantly related to system-level factors, such as year of diagnosis and geography, rather than individual patient factors.

     

Full population results from the core phase of CompLEEment-1, a phase 3b study of ribociclib plus letrozole as first-line therapy for advanced breast cancer in an expanded population

Purpose

CompLEEment-1 is a phase 3b trial in an expanded patient population with hormone receptor-positive (HR?+), human epidermal growth factor receptor-2–negative (HER2–) advanced breast cancer (ABC), the largest current trial of cyclin-dependent kinase 4 and 6 inhibitors in ABC.

Methods

Patients treated with?≤?1 line of prior chemotherapy and no prior endocrine therapy for ABC received ribociclib 600 mg/day (3-weeks-on/1-week-off) plus letrozole 2.5 mg/day and additionally monthly goserelin/leuprolide in men and pre-/perimenopausal women. Eligibility criteria allowed inclusion of patients with stable CNS metastases and an Eastern Cooperative Oncology Group performance status of 2. Primary objectives were safety and tolerability, and secondary objectives were efficacy and quality of life (QoL).

Results

Overall, 3,246 patients were evaluated (median follow-up 25.4 months). Rates of all-grade and grade?≥?3 treatment-related adverse events (AEs) were 95.2% and 67.5%, respectively. Treatment-related discontinuations due to all grade and grade?≥?3 AEs occurred in 12.9% and 7.3% of patients, respectively. Rates of all-grade AEs of special interest (AESI) were as follows: neutropenia (74.5%), increased alanine aminotransferase (16.2%), increased aspartate aminotransferase (14.1%), and QTcF prolongation (6.7%); corresponding values for grade?≥?3 AESI were 57.2%, 7.7%, 5.7%, and 1.0%, respectively. Median time to progression was 27.1 months (95% confidence interval, 25.7 to not reached). Patient QoL was maintained during treatment.

Conclusion

Safety and efficacy data in this expanded population were consistent with the MONALEESA-2 and MONALEESA-7 trials and support the use of ribociclib plus letrozole in the first-line setting for patients with HR?+?, HER2– ABC.

Trial registration

linicalTrials.gov NCT02941926.

     

Efficacy and cardiac safety of adjuvant trastuzumab-based chemotherapy regimens for HER2-positive early breast cancer

BackgroundTrastuzumab-based adjuvant therapy has become the standard of care for human epidermal growth factor receptor-2 (HER2)-positive early breast cancer (EBC). Both anthracycline- and non-anthracycline-containing trastuzumab regimens are approved in the United States, but cardiotoxicity is increased with anthracycline-containing regimens.DesignThis paper reviews published and reported efficacy and cardiac safety data from the adjuvant trastuzumab trials [National Surgical Adjuvant Breast and Bowel Project (NSABP) B-31/North Central Cancer Treatment Group (NCCTG) N9831, Breast Cancer International Research Group (BCIRG) 006, Herceptin Adjuvant (HERA), FinHer, and Programme Adjuvant Cancer Sein (PACS) 04].ResultsThe addition of trastuzumab to adjuvant chemotherapy significantly improved disease-free survival (from 24% to 58%) in five of the six trials. Overall survival was significantly improved (23%–35%) in the large trials. In NSABP B-31/ NCCTG N9831, 5.0%–6.6% of patients who received doxorubicin and cyclophosphamide (AC) were unable to receive trastuzumab. Cardiac event rate was highest in the anthracycline-containing trastuzumab arms (1.9%–3.8%) and lowest with the regimen of docetaxel, carboplatin, and trastuzumab (TCH) (0.4%).ConclusionsIncorporation of trastuzumab into anthracycline and non-anthracycline adjuvant chemotherapy regimens has substantially improved outcomes in HER2-postive EBC. The TCH regimen has the lowest rates of cardiac dysfunction, but uncertainty exists regarding the relative efficacy of TCH compared with anthracycline-containing trastuzumab regimens. Cardiac risk factor assessment can aid in selection of trastuzumab-based adjuvant therapy regimens.     

Trastuzumab emtansine (T-DM1) versus lapatinib plus capecitabine in patients with HER2-positive metastatic breast cancer and central nervous system metastases: a retrospective,exploratory analysis in EMILIA

BackgroundWe characterized the incidence of central nervous system (CNS) metastases after treatment with trastuzumab emtansine (T-DM1) versus capecitabine–lapatinib (XL), and treatment efficacy among patients with pre-existing CNS metastases in the phase III EMILIA study.Patients and methodsIn EMILIA, patients with human epidermal growth factor receptor 2 (HER2)-positive advanced breast cancer previously treated with trastuzumab and a taxane were randomized to T-DM1 or XL until disease progression. Patients with treated, asymptomatic CNS metastases at baseline and patients developing postbaseline CNS metastases were identified retrospectively by independent review; exploratory analyses were carried out.ResultsAmong 991 randomized patients (T-DM1 = 495; XL = 496), 95 (T-DM1 = 45; XL = 50) had CNS metastases at baseline. CNS progression occurred in 9 of 450 (2.0%) and 3 of 446 (0.7%) patients without CNS metastases at baseline in the T-DM1 and XL arms, respectively, and in 10 of 45 (22.2%) and 8 of 50 (16.0%) patients with CNS metastases at baseline. Among patients with CNS metastases at baseline, a significant improvement in overall survival (OS) was observed in the T-DM1 arm compared with the XL arm [hazard ratio (HR) = 0.38; P = 0.008; median, 26.8 versus 12.9 months]. Progression-free survival by independent review was similar in the two treatment arms (HR = 1.00; P = 1.000; median, 5.9 versus 5.7 months). Multivariate analyses demonstrated similar results. Grade ≥3 adverse events were reported in 48.8% and 63.3% of patients with CNS metastases at baseline administered T-DM1 and XL, respectively; no new safety signals were observed.ConclusionIn this retrospective, exploratory analysis, the rate of CNS progression in patients with HER2-positive advanced breast cancer was similar for T-DM1 and for XL, and higher overall in patients with CNS metastases at baseline compared with those without CNS metastases at baseline. In patients with treated, asymptomatic CNS metastases at baseline, T-DM1 was associated with significantly improved OS compared with XL.     

HER2-low status and response to neoadjuvant chemotherapy in HER2 negative early breast cancer

Purpose

Androgen receptor (AR) expression occurs in up to 86% of human epidermal growth factor receptor 2-positive (HER2+) breast cancers. In vitro, AR inhibitors enhance antitumor activity of trastuzumab, an anti-HER2 antibody, in trastuzumab-resistant HER2+?cell lines. This open-label, single-arm, phase II study evaluated the efficacy and safety of enzalutamide, an AR-signaling inhibitor, in patients with advanced HER2+?AR+?breast cancer previously treated with trastuzumab.

Methods

Eligible patients had measurable or non-measurable evaluable disease per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1, Eastern Cooperative Oncology Group status?≤?1, no history of brain metastases, and previously received?≥?1 anti-HER2 regimen for advanced disease. Patients received 160 mg oral enzalutamide daily and 6 mg/kg intravenous trastuzumab every 21 days until disease progression or unacceptable toxicity. Primary end point was clinical benefit rate at 24 weeks (CBR24); secondary end points included progression-free survival (PFS) and safety.

Results

Overall, 103 women were enrolled [median age 60 years (range?34–83)]; 62% had received?≥?3 lines of prior anti-HER2 therapy. CBR24, comprising patients with confirmed partial responses (5%) and durable stable disease at 24 weeks (19%), was 24% in the efficacy evaluable set (n?=?89). CBR24 did not seem related to AR-expression levels or hormone receptor status. Median PFS was 3.4 months (95% confidence interval 2.0–3.8). Overall, 97 (94%) patients experienced treatment-emergent adverse events (TEAEs), with fatigue most common (34%). Dyspnea (4%) and malignant neoplasm progression (3%) were the only TEAEs grade?≥?3 reported in?≥?3 patients. 22 patients (21%) reported serious TEAEs. Four patients (4%) experienced fatal, non-drug-related TEAEs.

Conclusions

Enzalutamide plus trastuzumab was well tolerated, and a subset of patients in this heavily pretreated population had durable disease control. Determination of biomarkers is needed to identify patients most likely to benefit from this combination.

ClinicalTrials.gov number

NCT02091960

     

Impact of Anti-HER2 Treatments Combined With Atezolizumab on the Tumor Immune Microenvironment in Early or Metastatic Breast Cancer: Results From a Phase Ib Study

BackgroundDespite advances, there continues to be unmet need in breast cancer. Combining anti–programmed death-ligand 1 (PD-L1) cancer immunotherapy atezolizumab with other targeted therapies may enhance T-cell–dependent cytolytic antitumor activity.MethodsThis open-label, phase Ib study evaluated the safety of atezolizumab-based combinations with antibody-dependent cellular cytotoxicity or antibody-drug conjugate (ADC) agents. Patients with unresectable human epidermal growth factor receptor 2–positive (HER2⁺) locally advanced or metastatic breast cancer (mBC) received atezolizumab with trastuzumab/pertuzumab, atezolizumab with the ADC ado-trastuzumab emtansine (T-DM1), or atezolizumab with trastuzumab/pertuzumab and docetaxel. In an early–breast cancer (eBC) “window of opportunity” study, patients with operable HER2⁺ locally advanced or inflammatory eBC received neoadjuvant atezolizumab with trastuzumab/pertuzumab or atezolizumab/T-DM1, followed by docetaxel, carboplatin, and trastuzumab/pertuzumab. Exploratory outcomes included tumor response and biomarkers.ResultsBy March 15, 2019, 73 patients were enrolled. Safety findings were consistent with the treatment components’ individual profiles. Objective responses were observed in 2 of 6 and 5 of 14 patients in 2 mBC cohorts receiving atezolizumab/T-DM1 and in 6 of 6 patients with mBC receiving atezolizumab, trastuzumab/pertuzumab, and docetaxel. PD-L1 in immune cells was the only biomarker that increased with atezolizumab/T-DM1. In the window of opportunity cohorts, PD-L1 levels and CD8⁺ T-cell infiltration increased from baseline in HER2⁺ eBC tumors receiving atezolizumab with trastuzumab/pertuzumab or T-DM1, irrespective of response. Despite increases in T-cell and B-cell gene signatures with trastuzumab/pertuzumab, but not T-DM1, neither combination promoted T-cell receptor clonal expansion.ConclusionAtezolizumab with antibody-dependent cellular cytotoxicity or ADC agents appears safe and may activate the adaptive immune system of patients with HER2⁺ eBC tumors more than those with mBC tumors.     

A Review of Trastuzumab Biosimilars in Early Breast Cancer and Real World Outcomes of Neoadjuvant MYL-1401O versus Reference Trastuzumab

The reduced cost of trastuzumab biosimilars has led to increased adoption for HER2-positive breast cancer. This review of trastuzumab biosimilars encompasses this development and real world clinical data in early breast cancer. In addition, we present a retrospective study evaluating the total pathological complete response (tpCR) rates (lack of residual invasive cancer in resected breast tissue and axillary nodes), of MYL-1401O to reference trastuzumab (TRZ) in the neoadjuvant setting for HER2+ early breast cancer (EBC) in Alberta, Canada. Neoadjuvant patients with HER2+ EBC treated with TRZ from November 2018–October 2019 and MYL-1401O from December 2019–September 2020 were identified. Logistic regression was used to control for variables potentially associated with tpCR: trastuzumab product, age, pre-operative T- and N-stage, grade, hormone receptor (HR)-status, HER2-status, chemotherapy regimen, and chemotherapy completion. tpCR was 35.6% in the MYL-1401O group (n = 59) and 40.3% in the TRZ (n = 77) group, p = 0.598. After controlling for clinically relevant variables, there was no significant difference in the odds of achieving tpCR in patients treated with TRZ versus MYL-1401O (OR 1.1, 95% CI 0.5–2.4, p = 0.850). tpCR rates were similar for patients treated with MYL-1401O compared to trastuzumab in our real world study of HER2+ neoadjuvant EBC and comparable to pivotal phase 3 trials.     

T-DM1 Efficacy in Patients With HER2-positive Metastatic Breast Cancer Progressing After a Taxane Plus Pertuzumab and Trastuzumab: An Italian Multicenter Observational Study

BackgroundT-DM1 improves progression-free survival (PFS) and overall survival (OS) in patients with metastatic human epidermal growth factor receptor 2-positive (HER2⁺) breast cancer progressing on prior trastuzumab plus a taxane. A paucity of data is available on T-DM1 efficacy after dual anti-HER2 blockade with pertuzumab and trastuzumab plus a taxane, which represents the current first-line standard of care. The present study is a retrospective/prospective evaluation of the efficacy and activity of second-line T-DM1 after front-line pertuzumab-based therapy.Patients and MethodsEligible patients were identified within the Gruppo Italiano Mammella (GIM) 14/BIOMETA study, a retrospective/prospective multicenter study on treatment patterns and outcomes of patients with metastatic breast cancer (ClinicalTrials.gov Identifier: NCT02284581). We searched for patients who received second-line T-DM1 after taxane plus trastuzumab and pertuzumab between November 15, 2013 and May 31, 2018. We calculated median PFS, median time to treatment failure (TTF), prolonged duration of therapy (PDT), objective response rate (ORR), and 1-year OS.ResultsOf 445 patients with HER2⁺ metastatic breast cancer, 77 were eligible for the analysis. At a median follow-up of 7 months, median PFS was 6.3 months (95% confidence intervals [CI], 4.8-7.7 months), and median TTF was 6.2 months (95% CI, 4-8.6 months). More than one-third of patients (37.6%; n = 29) experienced PDT with an ORR of 27.1%. At data cutoff, the median OS was not reached, and the 1-year OS was 82%.ConclusionsOur results show meaningful activity of T-DM1 after front-line pertuzumab plus trastuzumab and a taxane, with about 27% of patients having an objective response and 40% of patients achieving durable disease control.     

Epirubicin and docetaxel with or without capecitabine as neoadjuvant treatment for early breast cancer: final results of a randomized phase III study (ABCSG-24)

BackgroundThis randomized phase III trial compared pathologic complete response (pCR) rates of early breast cancer (EBC) following neoadjuvant epirubicin–docetaxel (ED) ± capecitabine (C), and evaluated the addition of trastuzumab in HER2-positive tumors.Patients and methodsPatients with invasive breast cancer (except T4d) were randomly assigned to receive six 3-weekly cycles of ED (both 75 mg/m²) ± C (1000 mg/m², twice daily, days 1–14). Patients with HER2-positive disease were further randomized to receive trastuzumab (8 mg/kg, then 6 mg/kg every 3 weeks) or not. Primary end point: pCR rate at the time of surgery.ResultsFive hundred thirty-six patients were randomized to ED (n = 266) or EDC (n = 270); 93 patients were further randomized to trastuzumab (n = 44) or not (n = 49). pCR rate was significantly increased with EDC (23.0% versus 15.4% ED, P = 0.027), and nonsignificantly further increased with trastuzumab (38.6% EDC versus 26.5% ED, P = 0.212). Rates of axillary node involvement at surgery and breast conservation were improved with EDC versus ED, but not significantly; the addition of trastuzumab had no further impact. Hormone receptor status, tumor size, grade, and C (all P ≤ 0.035) were independent prognostic factors for pCR. Trastuzumab added to ED ± C significantly increased the number of serious adverse events (35 versus 18; P = 0.020), mainly due to infusion-related reactions.ConclusionThese findings show that the integration of C into a neoadjuvant taxane-/anthracycline-based regimen is a feasible, safe, and effective treatment option, with incorporation of trastuzumab in HER2-positive disease.Clinical trial numberNCT00309556, www.clinicaltrials.gov.     

Responses to subsequent anti-HER2 therapy after treatment with trastuzumab-DM1 in women with HER2-positive metastatic breast cancer

BackgroundWomen with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (MBC) can respond to multiple lines of anti-HER2 therapy. It is unknown whether these patients will derive further clinical benefit following treatment with trastuzumab-MCC-DM1 (T-DM1).Patients and methods:We retrospectively identified HER2-positive MBC patients treated with T-DM1 and characterized outcomes during subsequent lines of anti-HER2 therapy. Response was determined by a blinded radiology review. Time-dependent analyses were carried out using Kaplan–Meier estimates.ResultsWe identified 23 patients treated with single-agent T-DM1 and report on the 20 patients who discontinued protocol therapy. All patients received trastuzumab-based metastatic therapy before initiation of T-DM1 [median 7 regimens (range 3–14)]. Of these 20 patients, 75% (15 of 20) received further therapy with or without anti-HER2 agents after discontinuing T-DM1. Partial response to either first- or second-subsequent line(s) of therapy was seen in 5 of 15 (33%) treated patients, including 33% (4 of 12) who received a regimen containing trastuzumab and/or lapatinib. Median durations of therapy to first- and second-subsequent regimens after T-DM1 were 5.5 and 6.4 months, respectively.ConclusionsIn heavily pretreated HER2-positive MBC patients, prior exposure to T-DM1 does not exhaust the potential benefit of ongoing anti-HER2 therapy with trastuzumab- and/or lapatinib-based regimens.     

Trastuzumab emtansine (T-DM1) plus docetaxel with or without pertuzumab in patients with HER2-positive locally advanced or metastatic breast cancer: results from a phase Ib/IIa study

BackgroundTrastuzumab emtansine (T-DM1) exhibited enhanced antitumor activity when combined with docetaxel or pertuzumab in preclinical studies. This phase Ib/IIa study assessed the feasibility of T-DM1 + docetaxel in patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (MBC) and T-DM1 + docetaxel ± pertuzumab in patients with HER2-positive locally advanced breast cancer (LABC).Patients and methodsPhase Ib (part 1) explored dose escalation, with T-DM1 + docetaxel administered for greater than or equal to six cycles in patients with MBC. Phase Ib (part 2) began with the maximum tolerated dose (MTD) identified in part 1. Patients with LABC were administered less than or equal to six cycles of T-DM1 + docetaxel or T-DM1 + docetaxel + pertuzumab. Phase IIa explored the MTDs identified in phase Ib.ResultsAdministered with T-DM1 (3.6 mg/kg), the docetaxel MTD was 60 mg/m² in MBC. In LABC, the MTD was 100 mg/m² docetaxel in combination with T-DM1 (3.6 mg/kg), given with granulocyte colony-stimulating factor (G-CSF). Administered with T-DM1 (3.6 mg/kg) + pertuzumab (840 mg, cycle 1; 420 mg, subsequent cycles), the docetaxel MTD in LABC was 75 mg/m² with G-CSF support. Neutropenia was the most common grade 3–4 adverse event (AE; MBC, 72% and LABC, 29%). In total, 48% (12/25) of MBC patients and 47% (34/73) of LABC patients experienced AEs requiring dose modification. In MBC (median prior systemic agents = 5), the objective response rate was 80.0% (20/25; 95% confidence interval [CI] 59.3–93.2) and the median progression-free survival was 13.8 months (range, 1.6–33.5). The pathologic complete response (ypT0/is, ypN0) rate in LABC was 60.3% (44/73; 95% CI 48.1–71.5). Pharmacokinetic analyses indicated a low risk of drug–drug interaction between T-DM1 and docetaxel.ConclusionsT-DM1 combined with docetaxel ± pertuzumab appeared efficacious in MBC or LABC; however, nearly half of patients experienced AEs requiring dose reductions with these T-DM1 combinations.ClinicalTrials.gov identifierNCT00934856.     

Clinical pharmacology of trastuzumab emtansine (T-DM1): an antibody–drug conjugate in development for the treatment of HER2-positive cancer

Purpose

Trastuzumab emtansine (T-DM1) is an antibody–drug conjugate comprising trastuzumab and DM1, a microtubule polymerization inhibitor, covalently bound via a stable thioether linker. To characterize the pharmacokinetics (PK) of T-DM1 in patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer, data from four studies (TDM3569g, TDM4258g, TDM4374g, and TDM4688g) of single-agent T-DM1 administered at 3.6?mg/kg every 3?weeks (q3w) were assessed in aggregate.

Methods

Multiple analytes—T-DM1, total trastuzumab (TT), DM1, and key metabolites—were quantified using enzyme-linked immunosorbent assays or liquid chromatography tandem mass spectrometry. PK parameters of T-DM1, TT, and DM1 exposure were calculated using standard noncompartmental approaches and correlated to efficacy (objective response rate) and safety (platelet counts, hepatic transaminase concentrations). Immunogenicity was evaluated by measuring anti-therapeutic antibodies (ATA) to T-DM1 after repeated dosing using validated bridging antibody electrochemiluminescence or enzyme-linked immunosorbent assays.

Results

PK parameters for T-DM1, TT, and DM1 were consistent across studies at cycle 1 and steady state. T-DM1 PK was not affected by residual trastuzumab from prior therapy or circulating extracellular domain of HER2. No significant correlations were observed between T-DM1 exposure and efficacy, thrombocytopenia, or increased concentrations of transaminases. Across the studies, ATA formation was detected in 4.5% (13/286) of evaluable patients receiving T-DM1 q3w.

Conclusions

The PK profile of single-agent T-DM1 (3.6?mg/kg q3w) is predictable, well characterized, and unaffected by circulating levels of HER2 extracellular domain or residual trastuzumab. T-DM1 exposure does not correlate with clinical responses or key adverse events.     

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 therapeutic approaches of HER2-positive breast cancer with a focus on neratinib maleate

Introduction: Breast cancer (BC) is the most common cancer in women. Human epidermal growth factor receptor 2-positive (HER2-positive) BC represents up to 15% of all BC cases and is associated with a poor prognosis. Despite the substantial improvement obtained with the addition to the treatment of trastuzumab in this subtype of BC, disease recurrence can still occur.

Areas covered: Anti-HER2 targeting drugs such as trastuzumab, pertuzumab, and T-DM1 have shown significant results in (neo)adjuvant setting. In this article, we will focus on available data for neratinib to reduce BC recurrence based mainly on the results of the ExteNET trial. This trial aimed to investigate whether neratinib can further reduce the risk of recurrence of patients diagnosed with HER2-positive BC. This trial demonstrated a significant reduction in the risk of invasive disease-free survival, particularly in hormone receptor-positive population. In addition, this review provides an expert opinion and analysis of the current situation in the adjuvant HER2-positive BC setting and in particular the escalation strategy of HER2 targeting.

Expert opinion: The treatment landscape of HER2 positive BC in this setting will evolve in the coming years with a need for clinical and molecular perspective tools to guide therapy.     

Economic evaluation of adjuvant trastuzumab emtansine in patients with HER2-positive early breast cancer and residual invasive disease after neoadjuvant taxane and trastuzumab–based treatment in Canada

BackgroundIn the katherine trial, adjuvant trastuzumab emtansine [T-DM1, Kadcyla (Genentech, South San Francisco, CA, U.S.A.)], compared with trastuzumab, significantly reduced the risk of recurrence or death by 50% (unstratified hazard ratio: 0.50; 95% confidence interval: 0.39 to 0.64; p < 0.0001) in patients with her2-positive early breast cancer (ebc) and residual invasive disease after neoadjuvant systemic treatment. A cost–utility evaluation, with probabilistic analyses, was conducted to examine the incremental cost per quality-adjusted life–year (qaly) gained associated with T-DM1 relative to trastuzumab, given the higher per-cycle cost of T-DM1.MethodsA Markov model comprising a number of health states was used to examine clinical and economic outcomes over a lifetime horizon from the Canadian public payer perspective. Patients entered the model in the invasive disease-free survival (idfs) state, where they received either T-DM1 or trastuzumab. Transition probabilities between the health states were derived from the katherine trial, Canadian life tables, and published literature from other relevant clinical trials (emilia, cleopatra, and {"type":"entrez-nucleotide","attrs":{"text":"M77001","term_id":"334927","term_text":"M77001"}}M77001). Resource use, costs, and utilities were derived from katherine, other clinical trials, published literature, provincial fee schedules, and clinical expert opinion. Sensitivity analyses were conducted for key assumptions and model parameters.ResultsCompared with trastuzumab, adjuvant T-DM1 was associated with a cost savings of $8,300 per patient and a 2.16 incremental qaly gain; thus T-DM1 dominated trastuzumab. Scenario analyses yielded similar results, with T-DM1 dominating trastuzumab or producing highly favourable incremental cost–utility ratios of less than $10,000 per qaly.ConclusionsAdjuvant T-DM1 monotherapy is a cost-effective strategy compared with trastuzumab alone in the treatment of patients with her2-positive ebc and residual invasive disease after neoadjuvant systemic treatment.     

The Global Need for a Trastuzumab Biosimilar for Patients With HER2-Positive Breast Cancer

Trastuzumab improves survival outcomes for patients with HER2-positive (HER2⁺) breast cancer, yet not all such women receive this important therapy. Trastuzumab was approved by the US Food and Drug Administration in 1998 and the European Medicines Agency in 2000 as treatment for HER2⁺ metastatic breast cancer (MBC). Observational studies between 2000 and 2015 in patients with HER2⁺ MBC suggest that nearly 12% in the United States, 27% to 54% in Europe, and 27.1% to 49.2% in China did not receive trastuzumab or any other HER2-targeted agent as first- and/or later-line for treatment of metastatic disease. In 2006, both agencies approved trastuzumab as adjuvant therapy for patients with HER2⁺ early breast cancer (EBC). Observational studies on real-world treatment patterns for HER2⁺ EBC between 2005 and 2015 suggest that 19.1% to 59.5% of patients across regions of North America, Europe, Australia, New Zealand, and China did not receive (neo)adjuvant trastuzumab. Data suggest that some patient subgroups, including older patients, those with HER2⁺/hormone receptor-positive disease, and women with small and/or node-negative HER2⁺ tumors, were less likely to receive anti-HER2 therapy. Barriers to accessing trastuzumab are multifactorial and include issues related to drug funding and high treatment costs for patients that have been reported worldwide. Herein, we review available literature on the use of, and barriers to, treatment with trastuzumab in patients with HER2⁺ breast cancer. We also discuss how the availability of safe and effective biosimilars might increase access to trastuzumab and allow greater use of anti-HER2 therapy, potentially improving patient outcomes.