Effects of Trastuzumab Emtansine (T-DM1) on QT Interval and Safety of Pertuzumab Plus T-DM1 in Patients With Previously Treated Human Epidermal Growth Factor Receptor 2-Positive Metastatic Breast Cancer

Belantamab mafodotin concentration-QTc relationships in patients with relapsed or refractory multiple myeloma from the DREAMM-1 and -2 studies

AIMS

To evaluate relationships between plasma concentrations of belantamab mafodotin, total monoclonal antibody, and its payload and changes in electrocardiogram (ECG) parameters in patients with relapsed or refractory multiple myeloma from the DREAMM-1 and DREAMM-2 studies.

METHODS

Hysteresis plots and linear regression analyses of pharmacokinetic (PK) analyte (belantamab mafodotin, total monoclonal antibody, and cytotoxic cysteine-maleimidocaproyl monomethyl auristatin F payload) concentrations vs. time-matched ECG parameters (absolute/change from baseline in QT interval corrected for RR interval [QTc/ΔQTc] and QT interval corrected for heart rate by Fridericia's formula [QTcF/ΔQTcF]) were performed. Concentrations of PK analyte required for a 10-ms increase in QTc in DREAMM-2 were calculated via simulation, as was the probability of ΔQTc/ΔQTcF exceeding 10 ms for the expected Cmax of PK analyte concentrations associated with the doses (2.5 and 3.4 mg/kg) administered in DREAMM-2.

RESULTS

Time-matched PK and ECG data from 290 patients (DREAMM-1, n = 73; DREAMM-2, n = 217) were analysed. Hysteresis plots did not clearly indicate any concentration-related prolongation in QTc or QTcF; regression analyses indicated a very small rate of increase in ΔQTc and ΔQTcF with increasing concentrations of PK analytes. Calculated concentrations of PK analyte required for a 10-ms prolongation in QTc were higher than the maximum analyte concentrations observed following treatment with belantamab mafodotin in DREAMM-2; the probability that each dose would prolong ΔQTc and ΔQTcF by >10 ms was 0 and <0.25%, respectively.

CONCLUSION

This study of belantamab mafodotin and its payload did not provide evidence of QT prolongation in patients with relapsed or refractory multiple myeloma at clinically relevant doses.

The ever-expanding landscape of antibody-drug conjugates (ADCs) in solid tumors: A systematic review

BACKGROUND

The advent of targeted therapies signaled novel avenues for more optimal oncological outcomes. Antibody-drug conjugates (ADCs) have risen as a cornerstone of the ever-expanding targeted therapy era. The purpose of this systematic review is to delineate the rapidly evolving clinical landscape of ADCs for solid tumors.

METHODS

A literature search was performed in Medline, Embase and Cochrane databases for phase II and III clinical trials. Outcomes of interest were the objective response rate, overall survival, progression-free survival and adverse events.

RESULTS

A total of 92 clinical trials (76 phase II and 16 phase III) evaluated the efficacy and safety of ADCs for a plethora of solid tumors. Out of the 30 investigated ADCs, 8 have received approval by regulatory organizations for solid tumors. Currently, 52 phase III clinical trials for ADCs are ongoing.

CONCLUSION

ADCs have shown promising results for several solid tumors and various cancer settings.

Effects of trastuzumab and trastuzumab emtansine on corrected QT interval and left ventricular ejection fraction in patients with metastatic (HER2+) breast cancer

BACKGROUND

Trastuzumab and trastuzumab emtansine are specific antibody and antibody-drug conjugates used in the treatment of human epidermal growth factor receptor 2 (HER2) positive metastatic breast cancer. The aim of this study was to test their effect on the QTc interval duration and left ventricular ejection fraction (LVEF) in our patients, two parameters used in evaluation of cardiotoxicity. From May 2015 to October 2017, 26 patients with preserved LVEF were included in the study. All of them were previously treated with standard paclitaxel and cisplatin-based chemotherapy regimens. Electrocardiogram (ECG) was recorded just before each trastuzumab dose application and six months after the last dose. Echocardiography with LVEF measurement was performed several days before the application of the initial dose, and six months after the last cycle. Later, 24 patients with metastatic disease received additional treatment with trastuzumab emtansine after six months and the same ECG and echocardiography protocol was performed again. Due to reduction in LVEF, two patients were discontinued from additional treatment.

RESULTS

A statistically significant QTc prolongation was found after each drug dose application, with an increase in mean QTc duration with every successive application, reaching the peak QTc values just before the fifth cycle of treatment. The QTc interval returned to its initial value six months after the last cycle (p < 0.001). These results were similar for both drugs. Mean LVEF before both treatment protocols was significantly higher compared to LVEF value after the treatment. LVEF before trastuzumab emtansine treatment was non-significantly higher than LVEF after trastuzumab treatment.

CONCLUSION

Trastuzumab and trastuzumab emtansine cardiotoxicity manifested as a significant and progressive QTc prolongation after successive drug applications, reaching the peak value just before the fifth cycle of both drugs. Both medications also caused statistically significant but asymptomatic LVEF reduction. Complete reversibility of cardiotoxic effects of both drugs was confirmed by QTc interval and LVEF normalisation after the treatment discontinuation.

Treatment-related adverse events associated with HER2-Targeted antibody-drug conjugates in clinical trials: a systematic review and meta-analysis

BACKGROUND

Given the increasing use of HER2-targeted antibody-drug conjugates (ADCs) worldwide, the summary of toxicity incidence and profiles of these drugs is crucial to provide reference for clinical application. This meta-analysis aimed to estimate the mean incidences of treatment-related adverse events of HER2-targeted ADCs and to investigate the differences between different drugs and cancer types.

METHODS

We performed a systematic search of literature in PubMed, Embase, Web of Science, and Scopus databases from inception to February 1, 2022 and the last search was updated to August 1, 2022. Published prospective clinical trials on single-agent of the US Food and Drug Administration approved HER2-targeted ADCs with available count data regarding treatment-related adverse events were included. The primary outcomes were pooled incidences of treatment-related adverse events and differences between different drugs and cancer types. The data synthesis was performed using a Bayesian hierarchical modelling method and the protocol was registered in PROSPERO (CRD42022331627).

FINDINGS

A total of 39 studies (37 trials) involving 7688 patients across five cancer types were included in the final analysis. On pooling the data using Bayesian hierarchical modelling, the overall mean incidence of all-grade adverse events, high-grade adverse events, serious adverse events, and adverse events that resulted in drug discontinuation were 98.29% (95% CrI, 97.33%-99.07%, τ = 1.49), 47.88% (95% CrI, 42.74%-53.17%, τ = 0.37), 19.45% (95% CrI, 15.70%-23.67%, τ = 0.55), and 10.52% (95% CrI, 8.03%-13.21%, τ = 0.56), respectively. The most common all-grade adverse events were nausea (41.57%; 95% CrI, 40.46%-42.64%, τ = 0.81), fatigue (35.86%; 95% CrI, 34.85%-36.96%, τ = 0.65), and decreased appetite (28.84%; 95% CrI, 22.93%-36.87%, τ = 0.76). The most common high-grade adverse events were thrombocytopenia (8.37%; 95% CrI, 7.75%-9.07%, τ = 0.71), anaemia (6.49%; 95% CrI, 5.86%-7.11%, τ = 1.06), and neutropenia (6.42%; 95% CrI, 5.76%-7.04%, τ = 1.21). We found no difference in the mean incidences of adverse events among different cancer types, as well as different dosing regimens. However, trastuzumab deruxtecan (T-DXd) appeared to have higher mean incidences of adverse events compared with trastuzumab emtansine (T-DM1), especially for the higher dose of T-DXd (6.4 mg/kg Q3W).

INTERPRETATION

The incidences of adverse events between two HER2-targeted ADCs were similar in different cancer types, but different HER2-targeted ADCs appeared to have different mean incidences of adverse events. The comprehensive summary of the adverse events of HER2-targeted ADCs is critical for clinicians caring for patients with cancer receiving HER2-targeted ADCs therapy.

FUNDING

The National Natural Science Foundation of China (Grant No. 82073402) and Key R&D Plan of Hubei Province, China (No.2020BCA060) funded this study.

Effect of Trastuzumab Deruxtecan on QT/QTc Interval and Pharmacokinetics in HER2-Positive or HER2-Low Metastatic/Unresectable Breast Cancer

HER2-targeted anticancer therapies may be associated with cardiovascular adverse events. This study evaluated effects of the HER2-targeted antibody-drug conjugate trastuzumab deruxtecan (T-DXd, DS-8201a) on QT/QTc interval and its pharmacokinetics. Patients with heavily pretreated, metastatic HER2-expressing breast cancer were enrolled at seven study sites in Japan. T-DXd was administered intravenously at 6.4 mg/kg on day 1 of each 21-day cycle. Primary end points were baseline-adjusted QTcF interval and pharmacokinetics parameters. Key secondary end points included safety events, serum concentration of T-DXd and DXd at the time of electrocardiographic measurements, and antitumor activity parameters. Among 51 total patients, 47 (92.2%) had HER2-low breast cancer (immunohistochemistry 1+ or 2+ and in situ hybridization-negative/equivocal/missing). Pharmacokinetic parameters after a single dose of T-DXd were consistent with previous studies. After multiple doses, T-DXd showed moderate accumulation (accumulation ratio (cycle 3/cycle 1), 1.35), but DXd showed minimal accumulation (1.09). The upper bound of the 90% confidence interval for mean ΔQTcF interval was < 10 ms at all timepoints, and at mean maximum serum concentration was also < 10 ms. Based on concentration-QT analysis, ΔQTcF increased with increasing concentrations of T-DXd and DXd. No clinically meaningful QTcF prolongation was observed. T-DXd had a manageable safety profile and showed antitumor activity in HER2-low breast cancer. In this study, a T-DXd dose of 6.4 mg/kg, higher than the 5.4-mg/kg dose currently approved for breast cancer, was not associated with clinically relevant QTcF prolongation in heavily pretreated patients with HER2-expressing metastatic breast cancer. This study adds to our understanding of T-DXd for treatment of HER2-low breast cancer.

HER2 in Metastatic Colorectal Cancer: Pathology, Somatic Alterations, and Perspectives for Novel Therapeutic Schemes

HER2 is an emerging biomarker in colorectal cancer (CRC). This oncogene plays an essential role in regulating cell proliferation, differentiation, migration, and, more in general, tumorigenesis and tumor progression. The most frequent types of HER2 alterations in CRC include gene amplification and missense mutations in 7-8% of CRC, often being mirrored by HER2 protein overexpression, representing founder events in solid tumors, including CRC. There are currently no approved HER2-targeted therapy guidelines for CRC; however, several studies have shown that HER2 can be effectively targeted in meta-static CRC settings. In this review, we discuss the current knowledge of HER2 testing in CRC and the immediate future perspectives for HER2 targeting in the metastatic setting.

Phase I Trial of a Novel Anti-HER2 Antibody-Drug Conjugate, ARX788, for the Treatment of HER2-Positive Metastatic Breast Cancer

PURPOSE

ARX788 is a novel antibody-drug conjugate (ADC) comprised of an anti-HER2 mAb and a potent tubulin inhibitor payload AS269 that is site-specifically conjugated to the antibody via a nonnatural amino acid incorporated into the antibody. Herein, we present the results of a phase I study of the safety, pharmacokinetics, and antitumor activity of ARX788 in patients with HER2-positive metastatic breast cancer (MBC).

PATIENTS AND METHODS

Patients with HER2-positive MBC received ARX788 at doses of 0.33, 0.66, 0.88, 1.1, 1.3, or 1.5 mg/kg every 3 weeks, or 0.88, 1.1, or 1.3 mg/kg every 4 weeks. The dose-limiting toxicity (DLT) was assessed for 84 days for pulmonary toxicity and at a duration of one cycle (21 or 28 days) for other toxicities.

RESULTS

In total, 69 patients were enrolled. No DLT or drug-related deaths occurred. Most patients (67/69; 97.1%) experienced at least one treatment-related adverse event (TRAE). Common (≥ 30%) TRAEs included an increase in aspartate aminotransferase, an increase in alanine aminotransferase, corneal epitheliopathy, alopecia, hypokalemia, interstitial lung disease (ILD)/pneumonitis, and an increase in aldosterone. While 34.8% of participants experienced ILD/pneumonitis, only 2 had a severity of grade 3. At 1.5 mg/kg every 3 weeks, the recommended phase II dose, the objective response rate was 65.5% [19/29, 95% confidence interval (CI), 45.7-82.1], the disease control rate was 100% (95% CI, 81.2-100), and the median progression-free survival was 17.02 months (95% CI, 10.09-not reached).

CONCLUSIONS

ARX788 demonstrated a manageable safety profile with promising preliminary signs of activity in patients with HER2-positive MBC who progressed on prior anti-HER2 therapies.

Caution the arrhythmia association with antibody-drug conjugates: a pharmacovigilance study

Arrhythmias associated with antibody-drug conjugates (ADCs) are rare but potentially life-threatening adverse events (AEs). No study has systemically compared arrhythmias associations for various marketed ADCs. This needs to be clarified to guide antitumor therapies. We extracted data of patients treated with ADCs registered between 2004 q1 and 2020 q3 from the US Food and Drug Administration adverse event reporting system (FAERS). The medical dictionary for regulatory activities was used to identify arrhythmias cases. Disproportionality analysis was performed by calculating the reporting odds ratios (ROR) with corresponding 95% confidence intervals (95% CI). Clinical characteristics of patients with ADCs-associated arrhythmias and the time to onset of arrhythmias following different ADCs were collected. A total of 140 reports were considered after inclusion criteria were used. Exposure to gemtuzumab ozogamicin (2.23, 1.67-2.97; 48 cases) and brentuximab vedotin (1.27, 1.00-1.61; 67 cases) were associated with a positive signal of arrhythmia. The highest number of arrhythmia reports was for brentuximab vedotin (n = 67). Also 88.00% of arrhythmia occurred within 60 days for all these ADCs. Arrhythmia was commonly reported in patients with hematologic tumors and breast cancer. In the time to onset of adverse events after administration, brentuximab vedotin was significantly earlier than gemtuzumab ozogamicin (38.21 vs. 40.50 days; P = 0.0093), and gemtuzumab ozogamicin was significantly earlier than trastuzumab emtansine (40.50 vs. 147.50 days; P = 0.0035). We reviewed arrhythmia adverse drug reactions associated with ADCs from the FAERS database. This study is practical for clinicians to enhance the management of arrhythmia associated with ADCs and improve ADCs treatment safety.

Assessment of racial differences in the incidence of thrombocytopenia induced by trastuzumab emtansine: a systematic review and meta-analysis

Background

Trastuzumab emtansine (T-DM1) has been proved to have value and efficacy in the treatment of advanced metastatic cancer, including in the adjuvant setting. However, there is increasing concern about T-DM1-induced thrombocytopenia (TCP), which shows racial differences in incidence. This meta-analysis aimed to evaluate differences in the incidence of T-DM1-related TCP between Asian and non-Asian patients by combining accessible information from all single-agent T-DM1 clinical trials published to date.

Methods

We conducted systematic searches of the PubMed, Embase, and the Cochrane Library databases to identify relevant clinical studies of T-DM1 that reported on safety, including the incidence of TCP, which were published between January 1980 and March 2020. Two reviewers were responsible for the screening and extraction of data. The pooled-effect estimate calculated with a fixed-effects or random-effects model was represented as incidence with 95% confidence intervals (CIs).

Results

A total of 29 studies involving 6,188 patients were included. The incidence of all-grade TCP in Asian patients and non-Asian patients was 0.39 (95% CI: 0.11–0.67) and 0.29 (95% CI: 0.23–0.35), respectively. The incidence of TCP of grade 3 or higher in Asians was 0.20 (95% CI: 0.10–0.29), compared with 0.02 (95% CI: 0.01–0.03) in non-Asians. Gastrointestinal cancer type and a T-DM1 treatment dose of 2.4 mg/kg Q3W were related to grade 3 or higher TCP events.

Discussion

Asian patients have a higher risk of developing TCP after receiving T-DM1 than non-Asian patients. Clinicians should be aware of the importance of careful observation of platelet count in patients receiving T-DM1 therapy.

Trastuzumab Emtansine: A Review of Its Adjuvant Use in Residual Invasive HER2-Positive Early Breast Cancer

Trastuzumab emtansine (Kadcyla^®), an antibody-drug conjugate of trastuzumab (Herceptin^®) connected by a thioether linker to the microtubule inhibitor DM1 (a cytotoxic derivative of maytansine), provides direct intracellular delivery of the potent cytotoxin DM1 to HER2-overexpressing cells, while retaining trastuzumab activity. Its approval in metastatic/advanced breast cancer (BC) has been extended to include single-agent adjuvant treatment of HER2-positive early BC in patients with residual invasive disease in the breast and/or lymph nodes after neoadjuvant taxane-based and HER2-targeted treatment. In the pivotal KATHERINE trial in this population, significantly more trastuzumab emtansine than trastuzumab recipients were estimated to be free of invasive disease recurrence at 3 years, with a 50% reduction in the risk of invasive disease recurrence or death. The tolerability of trastuzumab emtansine in early BC was consistent with its known safety profile; as expected, adverse events were more common with trastuzumab emtansine than with trastuzumab. Recently updated international and national treatment guidelines recommend trastuzumab emtansine as a preferred option in this high-risk BC population.

The mechanistic insights of the arrhythmogenic effect of trastuzumab

Cardiovascular diseases and cancers are the leading causes of deaths globally, and an increasing proportion of cancer patients is suffering from cardiac adverse effects of chemotherapeutic drugs. Trastuzumab, a monoclonal antibody that inhibits the activity of the human epidermal growth factor receptor 2 (HER2), is a potent targeted therapy for HER2-positive malignancies. Despite the impressive antineoplastic efficacy, the cardiotoxicity of trastuzumab frequently limits its use. Trastuzumab-induced cardiac contractile dysfunction has been extensively studied, yet the electrophysiological side effect of trastuzumab remains poorly characterized. Growing evidence from basic and clinical studies supports the link between trastuzumab treatment and arrhythmias. This review comprehensively summarizes relevant information from those reports, discusses their limitations, and suggests future research directions. We aim to encourage further investigations that will provide valuable insights to devise cardioprotective strategies against trastuzumab-induced cardiotoxicity.

Clinical pharmacology strategies in supporting drug development and approval of antibody-drug conjugates in oncology

Antibody–drug conjugates (ADCs) are important molecular entities in the treatment of cancer. These conjugates combine the target specificity of monoclonal antibodies with the potent anti-cancer activity of small-molecule therapeutics. The complex structure of ADCs poses unique challenges to characterize the drug’s pharmacokinetics (PKs) and pharmacodynamics (PDs) since it requires a quantitative understanding of the PK and PD properties of multiple different molecular species (e.g., ADC conjugate, total antibody and unconjugated cytotoxic drug). As a result, clinical pharmacology strategy of an ADC is rather unique and dependent on the linker/cytotoxic drug technology, heterogeneity of the ADC, PK and safety/efficacy profile of the specific ADC in clinical development. In this review, we summarize the clinical pharmacology strategies in supporting development and approval of ADCs using the approved ADCs as specific examples to illustrate the customized approach to clinical pharmacology assessments in their clinical development.

Efficacy and safety of HER2 inhibitors in combination with or without pertuzumab for HER2-positive breast cancer: a systematic review and meta-analysis

BACKGROUND

Although the dual anti-HER2 therapy, namely, pertuzumab plus trastuzumab and docetaxel, has shown promising results in HER2+ breast cancer patients, whether the dose, efficacy and safety of this treatment differs from those of other pertuzumab-based dual anti-HER2 therapies remain controversial. This systematic review evaluates the efficacy and safety of H (trastuzumab or trastuzumab emtansine ± chemotherapy) + P (pertuzumab) compared with those of H in HER2+ breast cancer patients.

METHODS

A comprehensive search was performed to identify eligible studies comparing the efficacy and safety of H + P versus H. The pathologic complete response (pCR), median progression-free survival (PFS) and overall survival (OS) were the primary outcomes, and safety was the secondary outcome. A subgroup analysis of pCR according to hormone receptor (HR) status was performed. All analyses were conducted using STATA 11.0.

RESULTS

Twenty-six studies (9872 patients) were identified. In the neoadjuvant setting, H + P significantly improved the pCR [odds ratio (OR) = 1.33; 95% confidence interval (CI), 1.08-1.63; p = 0.006]. In the metastatic setting, H + P significantly improved PFS [hazard ratios (HRs) = 0.75; 95% CI, 0.68-0.84; p < 0.001]. There was a trend towards better OS but that it did not reach statistical significance (HRs = 0.81; 95% CI, 0.64-1.03; p = 0.082). A subgroup analysis revealed that the HER2+/HR- patients who received H + P showed the highest increase in the pCR. Rash, diarrhea, epistaxis, mucosal inflammation, and anemia were significantly more frequently observed with H + P than with H, whereas myalgia was less frequent (OR = 0.91; 95% CI, 0.82-1.01; p = 0.072), and no significant difference in cardiac toxicity was observed between these therapies (OR = 1.26; 95% CI, 0.81-1.95; P = 0.309).

CONCLUSIONS

Our study confirms that H + P is superior to H in the (neo)adjuvant treatment of HER2+ breast cancer, and increase the risk of acceptable and tolerable toxicity (rash, diarrhea, epistaxis, mucosal inflammation, and anemia).

TRIAL REGISTRATION

A systematic review protocol was registered with PROSPERO (identification number: CRD42018110415 ).

Antibody-Drug Conjugates as Cancer Therapeutics: Past, Present, and Future

Antibody-drug conjugates (ADCs) represent an innovative therapeutic approach that provides novel treatment options and hope for patients with cancer. By coupling monoclonal antibodies (mAbs) to cytotoxic small-molecule payloads with a plasma-stable linker, ADCs offer the potential for increased drug specificity and fewer off-target effects than systemic chemotherapy. As evidence for the potential of these therapies, many new ADCs are in various stages of clinical development. Because their structure poses unique challenges to pharmacokinetic and pharmacodynamic characterization, it is critical to recognize the differences between ADCs and conventional chemotherapy in the design of ADC clinical development strategies. Although some properties may be determined mainly by either the mAb or the small-molecule portion, the behavior of these agents is not always predictable. Furthermore, because the absorption, distribution, metabolism, and excretion (ADME) of ADCs are influenced by all 3 of its components (mAb, linker, and payload), it is important to characterize the intact molecule, any target-mediated catabolic clearance of the mAb, and the ADME properties of the small-molecule payload. Here we describe key issues in the clinical development of ADCs, including considerations for designing first-in-human studies for ADCs. We discuss some difficulties of ADC pharmacokinetic characterization and current approaches to overcoming these challenges. Finally, we consider all aspects of clinical pharmacology assessment required during drug development, using examples from the literature to illustrate the discussion.

Incidence, Diagnosis, and Management of QT Prolongation Induced by Cancer Therapies: A Systematic Review

Background

The cardiovascular complications of cancer therapeutics are the focus of the burgeoning field of cardio‐oncology. A common challenge in this field is the impact of cancer drugs on cardiac repolarization (ie, QT prolongation) and the potential risk for the life‐threatening arrhythmia torsades de pointes. Although QT prolongation is not a perfect marker of arrhythmia risk, this has become a primary safety metric among oncologists. Cardiologists caring for patients receiving cancer treatment should become familiar with the drugs associated with QT prolongation, its incidence, and appropriate management strategies to provide meaningful consultation in this complex clinical scenario.

Methods and Results

In this article, we performed a systematic review (using Preferred Reporting Items of Systematic Reviews and Meta‐Analyses (PRISMA) guidelines) of commonly used cancer drugs to determine the incidence of QT prolongation and clinically relevant arrhythmias. We calculated summary estimates of the incidence of all and clinically relevant QT prolongation as well as arrhythmias and sudden cardiac death. We then describe strategies to prevent, identify, and manage QT prolongation in patients receiving cancer therapy. We identified a total of 173 relevant publications. The weighted incidence of any corrected QT (QTc) prolongation in our systematic review in patients treated with conventional therapies (eg, anthracyclines) ranged from 0% to 22%, although QTc >500 ms, arrhythmias, or sudden cardiac death was extremely rare. The risk of QTc prolongation with targeted therapies (eg, small molecular tyrosine kinase inhibitors) ranged between 0% and 22.7% with severe prolongation (QTc >500 ms) reported in 0% to 5.2% of the patients. Arrhythmias and sudden cardiac death were rare.

Conclusions

Our systematic review demonstrates that there is variability in the incidence of QTc prolongation of various cancer drugs; however, the clinical consequence, as defined by arrhythmias or sudden cardiac death, remains rare.

Safety and efficacy of the addition of pertuzumab to T-DM1 ± taxane in patients with HER2-positive, locally advanced or metastatic breast cancer: a pooled analysis

Background

The aim of this review was to systematically evaluate the safety and efficacy of the addition of pertuzumab to trastuzumab emtansine (T-DM1) ± taxane in patients with human epidermal growth factor receptor 2 (HER2)-positive, locally advanced breast cancer (LABC) or metastatic breast cancer (MBC).

Materials and methods

Several databases were searched for relevant clinical trials. The study characteristics, details of adverse events (AEs) and details of treatment efficacy were extracted for analysis.

Results

Six studies with 996 patients were included. Common AEs of T-DM1 + pertuzumab ± taxane included fatigue, diarrhea, nausea, epistaxis, peripheral neuropathy, increased aspartate transaminase (AST), increased alanine transaminase (ALT) and thrombocytopenia. Major grade ≥3 AEs of T-DM1 + pertuzumab ± taxane included thrombocytopenia, neutropenia, fatigue, increased ALT, anemia and peripheral neuropathy. The addition of pertuzumab to T-DM1 ± taxane led to higher risks of diarrhea (especially grade ≥3 diarrhea), rash and vomiting, and decreased risks of thrombocytopenia and grade ≥3 increased AST. The relative risks of the addition of pertuzumab to T-DM1 ± taxane for objective response (1.068, 95% CI 0.945–1.207) and clinical benefit (1.038, 95% CI 0.974–1.106) were not statistically significant.

Conclusion

Common AEs should be carefully monitored in HER2-positive LABC or MBC patients treated with T-DM1 + pertuzumab ± taxane. The addition of pertuzumab to T-DM1 ± taxane showed noninferior, but not superior, objective response rate and clinical benefit rate. However, more studies are needed to further verify these findings.

Splenic Enlargement and Bone Marrow Hyperplasia in Patients Receiving Trastuzumab-Emtansine for Metastatic Breast Cancer

BACKGROUND

An association between trastuzumab-emtansine (T-DM1) and splenic enlargement is reported in preclinical data, and has been noted anecdotally in patients receiving T-DM1 at our institution. Use of whole-body MRI examinations (WB-MRI) allows for detailed bone marrow assessment and semi-automated splenic volume calculations.

OBJECTIVE

To retrospectively evaluate changes in splenic volume versus evidence of bone marrow hyperplasia and/or changes in portal venous pressure in patients receiving T-DM1 for metastatic breast cancer.

PATIENTS AND METHODS

Twelve metastatic breast cancer patients underwent 29 WB-MRIs before and during T-DM1 therapy. Splenic volume, portal vein diameter, bone marrow diffusion-weighted normalised signal intensity (nSI), quantitative water diffusivity (apparent diffusion coefficient, ADC) and fat fraction (rF%) were measured and correlated.

RESULTS

Splenic volume increases were observed in 92% of patients. Mean splenic volume increased from 144 cm³ (95% CI 110-177 cm³) to 209 cm³ (95% CI 161-257 cm³) on T-DM1 therapy (p = 0.006). Splenic volume increases correlated with treatment duration (r² = 0.43). Bone marrow hyperplasia was evidenced by an increase in bone marrow nSI (3.5 to 4.8, p = 0.12), and decreases in rF% (64.3% to 57.3%, p = 0.12) and ADC (655 μm²/s to 543 μm²/s, p = 0.11). No changes to portal vein diameter were seen.

CONCLUSIONS

Previously unreported increases in splenic volume and bone marrow hyperplasia are observed on WB-MRI in patients on T-DM1 therapy. Caution must be applied to avoid misinterpreting T-DM1-induced bone marrow hyperplasia as diffuse disease progression in bone.

Breast cancer treatment-induced cardiotoxicity

INTRODUCTION

Breast cancer is the most frequent cancer affecting women worldwide. In every setting, the majority of women are treated with an evergrowing arsenal of therapeutic agents that have greatly improved their outcomes. However, these therapies can also be associated with significant adverse events. Areas covered: This review aims to thoroughly describe the current state of the evidence regarding the potential cardiotoxicity of agents commonly used in the treatment of breast cancer. These include chemotherapeutic agents, anti-HER2 therapies and CDK4/6 and mTOR inhibitors. Furthermore, issues related to the risk stratification and monitoring tools are explored. Expert opinion: Anthracycline- and trastuzumab-related cardiac toxicities have been extensively studied. Substantial evidence is now available concerning additional anti-HER2 agents such as pertuzumab, T-DM1 and tyrosine kinase inhibitors; overall, the cardiotoxicity profile is reassuring. Cardiac events due to endocrine therapy are mostly ischemic and, in the context of prolonged therapy, need specific attention. Novel agents implicated in the treatment of hormone receptor-positive disease are potentially arrhythmogenic and the exact risk will need to be further refined. As for today, assessment of baseline risk factors prior to treatment initiation and cardiac imaging before and during treatment remains the optimal way to prevent cardiac dysfunction. Cardioprotective therapy in primary prevention is still a matter of debate.

Twenty years of anti-HER2 therapy-associated cardiotoxicity

Over the past 20 years, the prognosis of HER2-positive breast cancer has been transformed by the development of anti-HER2 targeted therapies. In early clinical trials of trastuzumab (ie, the first anti-HER2 agent to be developed) cardiotoxicity became a major concern. In the first published phase 3 trial of trastuzumab, 27% of patients receiving anthracyclines and trastuzumab experienced cardiac events and 16% suffered from severe congestive heart failure. In subsequent trials conducted in advanced and early settings, the incidence of cardiac events was reduced through changes in chemotherapy regimens, more strict patient selection and close cardiac assessment. However, cardiotoxicity remains a significant problem in clinical practice that is likely to increase as new agents are approved and exposure times increase through improved patients' survival. Though numerous trials have led to improved understanding of many aspects of anti-HER2 therapy-related cardiotoxicity, its underlying physiopathology mechanisms are not well understood. The purpose of this article is to provide an in-depth review on anti-HER2 therapy-related cardiotoxicity, including data on both trastuzumab and the recently developed anti-HER2 targeted agents.

Trastuzumab emtansine in advanced human epidermal growth factor receptor 2-positive breast cancer

INTRODUCTION

Ado- trastuzumab emtansine (T-DM1) is a human epidermal growth factor receptor 2 (HER2)-targeted antibody-drug conjugate composed of trastuzumab, a stable linker (MCC), and the cytotoxic agent DM1 (derivative of maytansine; mertansine). T-DM1 retains the mechanisms of action of trastuzumab, but also acts as a, selectively delivered, tubulin inhibitor. Following antigen-mediated binding to the tumor cell, T-DM1 is endocytosed and intracellularly catabolized resulting in the release of its cytotoxic moiety.

AREAS COVERED

T-DM1 has completed Phase III development and compared favorably with the lapatinib/capecitabine combination with a superior response rate (objective response rate [ORR]) and duration of response, longer duration of disease control (progression-free survival [PFS]), prolonged overall survival and improved tolerability and quality of life in patients with prior treatment with trastuzumab and a taxane. In a separate Phase III, T-DM1 was compared with any other chosen regimen in patients who had at least received two prior HER2-directed therapies. T-DM1 nearly doubled PFS.

EXPERT OPINION

T-DM1 (Kadcyla) has become the treatment of choice in second-line and beyond for patients with advanced HER2-expressing breast cancer.

Trastuzumab emtansine: a review of its use in patients with HER2-positive advanced breast cancer previously treated with trastuzumab-based therapy

Trastuzumab emtansine (Kadcyla™) is an antibody-drug conjugate consisting of the humanized anti-human epidermal growth factor receptor (HER) 2 antibody trastuzumab covalently linked to the highly potent microtubule inhibitory drug DM1 (a cytotoxic derivative of maytansine) via a stable thioether linker. Intravenous trastuzumab emtansine was recently approved for use in patients with HER2-positive, unresectable, locally advanced (in the EU) or metastatic (in the USA and EU) breast cancer who had previously received trastuzumab and a taxane (separately or in combination), making it the first antibody-drug conjugate approved in this indication. This article reviews the efficacy and tolerability of trastuzumab emtansine in these patients and summarizes its pharmacology. In the well-designed EMILIA study, trastuzumab emtansine significantly prolonged progression-free survival and overall survival, relative to treatment with lapatinib plus capecitabine, in patients with HER2-positive, unresectable, locally advanced or metastatic breast cancer who were previously treated with trastuzumab and a taxane. Trastuzumab emtansine was generally well tolerated in this study, with <6% of patients discontinuing treatment because of adverse events. Based on its efficacy and favourable tolerability, the US National Comprehensive Cancer Network guidelines recommend trastuzumab emtansine as the preferred option in patients with HER2-positive metastatic breast cancer who have received previous trastuzumab-based therapy.

Feasibility and cardiac safety of trastuzumab emtansine after anthracycline-based chemotherapy as (neo)adjuvant therapy for human epidermal growth factor receptor 2-positive early-stage breast cancer

PURPOSE

Trastuzumab emtansine (T-DM1), an antibody-drug conjugate comprising the cytotoxic agent DM1, a stable linker, and trastuzumab, has demonstrated substantial activity in human epidermal growth factor receptor 2 (HER2) -positive metastatic breast cancer, raising interest in evaluating the feasibility and cardiac safety of T-DM1 in early-stage breast cancer (EBC).

PATIENTS AND METHODS

Patients (N = 153) with HER2-positive EBC and prechemotherapy left ventricular ejection fraction (LVEF) ≥ 55% received (neo)adjuvant doxorubicin plus cyclophosphamide or fluorouracil plus epirubicin plus cyclophosphamide followed by T-DM1 for four cycles. Patients could then receive three to four cycles of optional docetaxel with or without trastuzumab. T-DM1 was then resumed with optional radiotherapy (sequential or concurrent) for 1 year (planned) of HER2-directed therapy. The coprimary end points were rate of prespecified cardiac events and safety.

RESULTS

Median follow-up was 24.6 months. No prespecified cardiac events or symptomatic congestive heart failures were reported. Four patients (2.7%) had asymptomatic LVEF declines (≥ 10 percentage points from baseline to LVEF < 50%), leading to T-DM1 discontinuation in one patient. Of 148 patients who received ≥ one cycle of T-DM1, 82.4% completed the planned 1-year duration of HER2-directed therapy. During T-DM1 treatment, 38.5% and 2.7% of patients experienced grade 3 and 4 adverse events, respectively. Approximately 95% of patients receiving T-DM1 plus radiotherapy completed ≥ 95% of the planned radiation dose with delay ≤ 5 days.

CONCLUSION

Use of T-DM1 for approximately 1 year after anthracycline-based chemotherapy was feasible and generally well tolerated by patients with HER2-positive EBC, providing support for phase III trials of T-DM1 in this setting.

Trastuzumab, in combination with carboplatin and docetaxel, does not prolong the QT interval of patients with HER2-positive metastatic or locally advanced inoperable solid tumors: results from a phase Ib study

Purpose

This study evaluated the potential effect of trastuzumab on the electrocardiogram (ECG) QT interval and assessed the potential pharmacokinetic interaction between trastuzumab and carboplatin. Here, we report the QT and safety results.

Methods

Patients with metastatic or inoperable HER2-positive solid tumors received docetaxel and carboplatin on Day 1 of each 3-week (q3w) cycle. Trastuzumab was administered intravenously, as an accelerated loading dose regimen, on Cycle 1, Day 2 and Cycle 1, Day 8, and then on Day 1 of each subsequent q3w cycle. ECG assessments were performed pre- and posttrastuzumab infusion in the first two cycles. Fridericia’s correction was applied to QT intervals (QTcF). Baseline-adjusted QTcF intervals (the change from baseline) and their 90 % confidence intervals (CIs) were calculated.

Results

The study enrolled 59 patients. At all time points, the 90 % CI upper bound for the mean baseline-adjusted QTcF was <10 ms. At steady-state serum trastuzumab concentrations, the mean baseline-adjusted QTcF interval was −8.4 ms (90 % CI −11.1, −5.7). No patient exhibited an absolute QTcF interval of >480 ms. No relationship was observed between trastuzumab concentration and baseline-adjusted QTcF interval. At data cutoff, 84.5 % of patients had experienced grade ≥3 adverse events, the most common of which were hematologic and as expected. Left ventricular ejection fraction remained ≥45 % in all patients during the study.

Conclusions

The results suggest that trastuzumab had no clinically relevant effect on QTcF interval. The safety profile of trastuzumab in combination with carboplatin and docetaxel was consistent with the known safety profile of this combination.

Electronic supplementary material

The online version of this article (doi:10.1007/s00280-014-2603-9) contains supplementary material, which is available to authorized users.

Trastuzumab emtansine in human epidermal growth factor receptor 2-positive metastatic breast cancer: an integrated safety analysis

PURPOSE

The antibody-drug conjugate trastuzumab emtansine (T-DM1) combines the cytotoxic activity of DM1 with the human epidermal growth factor receptor 2 (HER2) -targeted, antitumor properties of trastuzumab. T-DM1 has shown activity in phase I and II single-arm studies in patients with pretreated HER2-positive metastatic breast cancer (MBC) and has demonstrated superior efficacy and improved tolerability versus standard MBC treatments in randomized phase II and III studies. This analysis, combining available data from all single-agent T-DM1 studies to date, was conducted to better define the T-DM1 safety profile.

PATIENTS AND METHODS

Six studies in patients with HER2-positive MBC who received T-DM1 3.6 mg/kg every 3 weeks and follow-up data from patients in an extension study were analyzed. Analyses included adverse events (AEs) by grade; AEs leading to death, drug discontinuation, or dose reduction; and select AEs.

RESULTS

Among 884 T-DM1-exposed patients, the most commonly reported all-grade AEs were fatigue (46.4%), nausea (43.0%), thrombocytopenia (32.2%), headache (29.4%), and constipation (26.5%). The most common grade 3 to 4 AEs were the laboratory abnormalities of thrombocytopenia (11.9%) and increased AST serum concentration (4.3%). These were manageable and not generally associated with clinical symptoms. There were 12 AE-related deaths. AEs resulted in dose reductions in 17.2% of patients and drug discontinuations in 7.0%.

CONCLUSION

In this analysis of 884 T-DM1-exposed patients, grade 3 or greater AEs were infrequent and typically asymptomatic and manageable. This favorable safety profile makes T-DM1 treatment suitable for exploration in other breast cancer settings.

Population pharmacokinetics of trastuzumab emtansine (T-DM1), a HER2-targeted antibody-drug conjugate, in patients with HER2-positive metastatic breast cancer: clinical implications of the effect of covariates

Purpose

Trastuzumab emtansine (T-DM1) is an antibody–drug conjugate comprising the humanized monoclonal antibody trastuzumab linked to DM1, a highly potent cytotoxic agent. A population pharmacokinetic (PK) analysis was performed to estimate typical values and interindividual variability of T-DM1 PK parameters and the effects of clinically relevant covariates.

Methods

Serum samples were collected from 671 patients with human epidermal growth factor receptor 2-positive locally advanced or metastatic breast cancer (MBC) who received single-agent T-DM1 in five phase I to phase III studies. Nonlinear mixed-effects modeling with the first-order conditional estimation method was used.

Results

A linear two-compartment model with first-order elimination from the central compartment described T-DM1 PKs in the clinical dose range. T-DM1 elimination clearance was 0.676 L/day, volume of distribution in the central compartment (V_c) was 3.127 L, and terminal elimination half-life was 3.94 days. Age, race, region, and renal function did not influence T-DM1 PK. Given the low-to-moderate effect of all statistically significant covariates on T-DM1 exposure, none of these covariates is expected to result in a clinically meaningful change in T-DM1 exposure.

Conclusions

T-DM1 PK properties are consistent and predictable in patients. A further refinement of dose based on baseline covariates other than body weight for the current 3.6 mg/kg regimen would not yield clinically meaningful reductions in interindividual PK variability in patients with MBC.

Electronic supplementary material

The online version of this article (doi:10.1007/s00280-014-2500-2) contains supplementary material, which is available to authorized users.

Preclinical safety profile of trastuzumab emtansine (T-DM1): mechanism of action of its cytotoxic component retained with improved tolerability

Trastuzumab emtansine (T-DM1) is the first antibody-drug conjugate (ADC) approved for patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer. The therapeutic premise of ADCs is based on the hypothesis that targeted delivery of potent cytotoxic drugs to tumors will provide better tolerability and efficacy compared with non-targeted delivery, where poor tolerability can limit efficacious doses. Here, we present results from preclinical studies characterizing the toxicity profile of T-DM1, including limited assessment of unconjugated DM1. T-DM1 binds primate ErbB2 and human HER2 but not the rodent homolog c-neu. Therefore, antigen-dependent and non-antigen-dependent toxicity was evaluated in monkeys and rats, respectively, in both single- and repeat-dose studies; toxicity of DM1 was assessed in rats only. T-DM1 was well tolerated at doses up to 40 mg/kg (~4400 μg DM1/m(2)) and 30 mg/kg (~ 6000 μg DM1/m(2)) in rats and monkeys, respectively. In contrast, DM1 was only tolerated up to 0.2mg/kg (1600 μg DM1/m(2)). This suggests that at least two-fold higher doses of the cytotoxic agent are tolerated in T-DM1, supporting the premise of ADCs to improve the therapeutic index. In addition, T-DM1 and DM1 safety profiles were similar and consistent with the mechanism of action of DM1 (i.e., microtubule disruption). Findings included hepatic, bone marrow/hematologic (primarily platelet), lymphoid organ, and neuronal toxicities, and increased numbers of cells of epithelial and phagocytic origin in metaphase arrest. These adverse effects did not worsen with chronic dosing in monkeys and are consistent with those reported in T-DM1-treated patients to date.