HER2-Selective and Reversible Tyrosine Kinase Inhibitor Tucatinib Potentiates the Activity of T-DM1 in Preclinical Models of HER2-positive Breast Cancer.

The oncogenic receptor HER2 is overexpressed in many cancers, including up to 20% of breast cancers. Despite the availability of HER2-targeted treatments, patients' disease often progresses during therapy, underscoring the need for novel treatment strategies. The addition of tucatinib, a reversible, highly selective HER2 tyrosine kinase inhibitor (TKI), to treatment with trastuzumab and capecitabine significantly improved survival outcomes of patients with HER2-positive metastatic breast cancer, including those with active brain metastases. We rationalized that combining tucatinib with other HER2-targeting agents with complementary mechanisms of action would further increase efficacy against tumors. We characterized the activity of tucatinib with the antibody­drug conjugate T-DM1 in preclinical models of breast cancer, including HER2-positive breast cancer cells and patient-derived xenograft (PDX) models. Mechanistic details on tucatinib activity were obtained in internalization and catabolism studies. In combination, tucatinib and T-DM1 showed an enhanced, often synergistic, cytotoxic response and demonstrated improved antitumor activity in vivo, including in PDX models refractory to T-DM1 single-agent activity. Mechanistically, tucatinib mediated an increase in inactive HER2 molecules at the cell surface through inhibition of HER2 ubiquitination, resulting in increased internalization and catabolism of T-DM1. The combination was correlated with enhanced HER2 pathway inhibition, decreased proliferation, and increased apoptosis. In a xenograft model of brain metastasis, tucatinib penetrated intracranial tumor tissues, inhibiting tumor growth and improving survival. These results suggest that tucatinib may be the optimal TKI partner for HER2-targeted therapies and support clinical studies of its combination with T-DM1, including in patients with brain metastases. SIGNIFICANCE: The preclinical findings in breast cancer models presented here demonstrate that combining tucatinib with T-DM1 enhances the antitumor activity of either agent alone, supporting clinical studies of the combination in HER2-positive breast cancer, including in patients with brain metastases, which remains an important unmet medical need.

Physicochemical and biological impact of metal-catalyzed oxidation of IgG1 monoclonal antibodies and antibody-drug conjugates via reactive oxygen species.

Biotherapeutics are exposed to common transition metal ions such as Cu(II) and Fe(II) during manufacturing processes and storage. IgG1 biotherapeutics are vulnerable to reactive oxygen species (ROS) generated via the metal-catalyzed oxidation reactions. Exposure to these metal ions can lead to potential changes to structure and function, ultimately influencing efficacy, potency, and potential immunogenicity of the molecules. Here, we stress four biotherapeutics of the IgG1 subclass (trastuzumab, trastuzumab emtansine, anti-NaPi2b, and anti-NaPi2b-vc-MMAE) with two common pharmaceutically relevant metal-induced oxidizing systems, Cu(II)/ ascorbic acid and Fe(II)/ H2O2, and evaluated oxidation, size distribution, carbonylation, Fc effector functions, antibody-dependent cellular cytotoxicity (ADCC) activity, cell anti-proliferation and autophaghic flux. Our study demonstrates that the extent of oxidation was metal ion-dependent and site-specific, leading to decreased FcγRIIIa and FcRn receptor binding and subsequently potentially reduced bioactivity, though antigen binding was not affected to a great extent. In general, the monoclonal antibody (mAb) and corresponding antibody-drug conjugate (ADC) showed similar impacts to product quality when exposed to the same metal ion, either Cu(II) or Fe(II). Our study clearly demonstrates that transition metal ion binding to therapeutic IgG1 mAbs and ADCs is not random and that oxidation products show unique structural and functional ramifications. A critical outcome from this study is our highlighting of key process parameters, route of degradation, especially oxidation (metal catalyzed or via ROS), on the CH1 and Fc region of full-length mAbs and ADCs.Abbreviations: DNPH 2,4-dinitrophenylhydrazine; ADC Antibody drug conjugate; ADCC Antibody-dependent cellular cytotoxicity; CDR Complementary determining region; DTT Dithiothreitol; HMWF high molecular weight form; LC-MS Liquid chromatography-mass spectrometry; LMWF low molecular weight forms; MOA Mechanism of action; MCO Metal-catalyzed oxidation; MetO Methionine sulfoxide; mAbs Monoclonal antibodies; MyBPC Myosin binding protein C; ROS Reactive oxygen species; SEC Size exclusion chromatography.

Efficacy of trastuzumab emtansine (T-DM1) and lapatinib after dual HER2 inhibition with trastuzumab and pertuzumab in patient with metastatic breast cancer: Retrospective data from a French multicenter real-life cohort.

PURPOSE: Trastuzumab-emtansine (T-DM1), as well as lapatinib plus capecitabine were proven effective in two Phase III studies, following first-line trastuzumab plus a taxane. The introduction of dual HER2 blockade by trastuzumab and pertuzumab as first-line has positioned T-DM1 into second-line, and lapatinib plus capecitabine beyond, without formal evaluation of these strategies. METHODS: ESME Data Platform (NCT03275311) included individual data from all patients aged ≥18 years, in whom first-line treatment for metastatic breast cancer (MBC) was initiated between January 1, 2008 and December 31, 2016 in one of the 18 French Comprehensive Cancer Centers. The efficacy of T-DM1 and lapatinib plus capecitabine combination, following double blockade associating trastuzumab and pertuzumab were evaluated in this national real-life database. Eligibility criteria were: female, MBC, HER2+ tumor, first-line taxane-based chemotherapy and dual HER2-blockage by trastuzumab plus pertuzumab. Cohort A received second-line T-DM1, and Cohort B second-line T-DM1 and third or fourth-line lapatinib plus capecitabine. RESULTS: Cohort A comprised 233 patients, and Cohort B 47 patients. Median progression-free survival (PFS) was 7.1 months in Cohort A and 4.6 months in Cohort B. Median overall survival were 36.7 months and 12.9 months, respectively. PFS was significantly dependent on the preceding treatment line's duration. In cohort A, HER2 expression status was a significant predictive factor of PFS. CONCLUSION: First-line trastuzumab plus pertuzumab do not markedly diminish T-DM1's efficacy in second-line. Similarly, sequential treatment with trastuzumab plus pertuzumab then T-DM1 does not noticeably modify the efficacy of lapatinib plus capecitabine.

Eficacia y seguridad de trastuzumab emtansina para el tratamiento adyuvante de pacientes adultos con cáncer de mama HER2 positivo localmente avanzado con enfermedad invasiva residual después de tratamiento neoadyuvante con trastuzumab y quimioterapia / Efficacy and safety of trastuzumab emtansine for the adjuvant treatment of adult patients with locally advanced her2-positive breast cancer with residual invasive disease after neoadjuvant treatment with trastuzumab and chemotherapy

ANTECEDENTES: En el marco de la metodología ad hoc para evaluar solicitudes de tecnologías sanitarias, aprobada mediante Resolución de Institución de Evaluación de Tecnologías en Salud e Investigación N° 111-IETSI-ESSALUD-2021, se ha elaborado el presente dictamen, el que expone la evaluación de la eficacia y seguridad de trastuzumab emtansina para el tratamiento adyuvante de pacientes adultos con cáncer de mama, HER2 positivo, localmente avanzado con enfermedad invasiva residual después de tratamiento neoadyuvante con trastuzumab y quimioterapia. Así, el Dr. Rodrigo Auqui Flores, médico especialista en Oncología del Servicio de Oncología Médica del Hospital Nacional Almanzor Aguinaga Asenjo de la Red Asistencial Lambayeque, siguiendo la Directiva N° 003-IETSI-ESSALUD-2016, envió al Instituto de Evaluación de Tecnologías en Salud e Investigación ­ IETSI la solicitud de uso fuera del petitorio del producto trastuzumab emtansina. ASPECTOS GENERALES: A nivel mundial y en el Perú, el cáncer de mama es el cáncer que se diagnostica con más frecuencia entre las mujeres y es la principal causa de muerte por cáncer en las mismas (Institute for Health Metrics and Evaluation 2021). El cáncer de mama es una enfermedad heterogénea y fenotípicamente diversa, compuesta por varios subtipos biológicos que tienen un comportamiento distinto. La amplificación o sobreexpresión del oncogén del receptor 2 del factor de crecimiento epidérmico humano (HER2) está presente en aproximadamente el 15 % de los cánceres de mama invasivos primarios (Burstein 2021). Las mujeres con cáncer de mama, localmente avanzado, positivo para HER2, a menudo requieren tratamiento neoadyuvante (preoperatorio) con trastuzumab y quimioterapia. El tratamiento neoadyuvante tiene como objetivo reducir el tamaño del tumor antes de la cirugía. Si bien la mayoría de pacientes presenta una respuesta patológica completa después del tratamiento neoadyuvante, existe un grupo de pacientes que experimentan enfermedad invasiva residual. Aunque, hasta la fecha, no existe evidencia sólida que demuestre que una respuesta patológica completa prediga un efecto sobre los desenlaces finales a largo plazo, como la sobrevida global (SG) (Cortazar et al. 2014), algunos autores sugieren que la ausencia de una respuesta patológica completa estaría asociada con un peor pronóstico (von Minckwitz et al. 2019). Adicional, e independientemente a la respuesta al tratamiento neoadyuvante, en general, todas las pacientes reciben tratamiento adyuvante (posoperatorio). El tratamiento adyuvante tiene como objetivo reducir el riesgo de recurrencia después de la cirugía (Burstein 2021; NICE 2020). METODOLOGÍA: Se realizó una búsqueda sistemática utilizando las bases de datos PubMed, Cochrane Library y LILACS. Además, se realizó una búsqueda dentro de bases de datos pertenecientes a grupos que realizan evaluaciones de tecnologías sanitarias (ETS) y guías de práctica clínica (GPC), incluyendo el Scottish Medicines Consortium (SMC), el National Institute for Health and Care Excellence (NICE), la Canadian Agency for Drugs and Technologies in Health (CADTH), la Haute Autorité de Santé (HAS), el Institute for Quality and Efficiency in Health Care (IQWiG), el Instituto de Evaluación Tecnológica en Salud de Colombia (IETS), la Comissáo Nacional de Incorpornáo de Tecnologias no Sistema Único de Saúde (CONITEC), entre otros. Asimismo, se revisó la Base Regional de Informes de Evaluación de Tecnologías en Salud de las Américas (BRISA) y páginas web de sociedades especializadas en el manejo del cáncer como la National Comprehensive Cancer Network (NCCN), la European Society for Medical Oncology (ESMO), y la American Society of Clinical Oncology (ASCO). Adicionalmente, se hizo una búsqueda en las páginas web del registro de ensayos clínicos administrado por la Biblioteca Nacional de Medicina de los Estados Unidos (https://clinicaltrials.gov/) y de la International Clinical Trial Registry Platform (ICTRP) (https://apps.who.int/trialsearch/), para identificar ensayos clínicos en curso o cuyos resultados no hayan sido publicados. RESULTADOS: La búsqueda de literatura permitió identificar diez publicaciones que aportan información de relevancia para fines de la presente actualización: tres GPC realizadas por la NCCN (NCCN 2021), la ESMO (Cardoso et al. 2019), y la ASCO (Denduluri et al. 2021), cinco ETS elaboradas por el NICE de Inglaterra y Gales (NICE 2020), el SMC de Escocia (SMC 2020), la CADTH de Canadá (CADTH 2020), el IQWiG de Alemania (IQWiG 2020), y la HAS de Francia (HAS 2020), y dos publicaciones del ECA KATHERINE (von Minckwitz et al. 2019; Conte et al. 2020). CONCLUSIÓN: Por todo lo expuesto, el IETSI no aprueba el uso de trastuzumab emtansina para el tratamiento adyuvante de pacientes adultos con cáncer de mama, HER2 positivo, localmente avanzado con enfermedad invasiva residual después de tratamiento neoadyuvante con trastuzumab y quimioterapia.

Acute eosinophilic pneumonia: a fatal reaction to ado-trastuzumab.

Ado-trastuzumab emtansine (T-DM1) is a monoclonal antibody drug conjugate approved for the treatment of HER2-positive breast cancers. Presented here is a case report of a patient who developed fatal pulmonary toxicity in the form of acute eosinophilic pneumonia while undergoing treatment with T-DM1. Prior to beginning T-DM1 therapy, this patient had been treated with two HER2-targeted agents (trastuzumab, pertuzumab) per National Comprehensive Cancer Network (NCCN) guidelines. This case represents a novel presentation of toxicity associated with T-DM1 while perhaps demonstrating additive toxicity associated with multiple lines of HER2 targeted therapies.

Trastuzumab Conjugated Superparamagnetic Iron Oxide Nanoparticles Labeled with 225Ac as a Perspective Tool for Combined α-Radioimmunotherapy and Magnetic Hyperthermia of HER2-Positive Breast Cancer.

It has been proven and confirmed in numerous repeated tests, that the use of a combination of several therapeutic methods gives much better treatment results than in the case of separate therapies. Particularly promising is the combination of ionizing radiation and magnetic hyperthermia in one drug. To achieve this objective, magnetite nanoparticles have been modified in their core with α emitter 225Ac, in an amount affecting only slightly their magnetic properties. By 3-phosphonopropionic acid (CEPA) linker nanoparticles were conjugated covalently with trastuzumab (Herceptin®), a monoclonal antibody that recognizes ovarian and breast cancer cells overexpressing the HER2 receptors. The synthesized bioconjugates were characterized by transmission electron microscopy (TEM), Dynamic Light Scattering (DLS) measurement, thermogravimetric analysis (TGA) and application of 131I-labeled trastuzumab for quantification of the bound biomolecule. The obtained results show that one 225Ac@Fe3O4-CEPA-trastuzumab bioconjugate contains an average of 8-11 molecules of trastuzumab. The labeled nanoparticles almost quantitatively retain 225Ac (>98%) in phosphate-buffered saline (PBS) and physiological salt, and more than 90% of 221Fr and 213Bi over 10 days. In human serum after 10 days, the fraction of 225Ac released from 225Ac@Fe3O4 was still less than 2%, but the retention of 221Fr and 213Bi decreased to 70%. The synthesized 225Ac@Fe3O4-CEPA-trastuzumab bioconjugates have shown a high cytotoxic effect toward SKOV-3 ovarian cancer cells expressing HER2 receptor in-vitro. The in-vivo studies indicate that this bioconjugate exhibits properties suitable for the treatment of cancer cells by intratumoral or post-resection injection. The intravenous injection of the 225Ac@Fe3O4-CEPA-trastuzumab radiobioconjugate is excluded due to its high accumulation in the liver, lungs and spleen. Additionally, the high value of a specific absorption rate (SAR) allows its use in a new very perspective combination of α radionuclide therapy with magnetic hyperthermia.

Neratinib: an option for HER2-positive metastatic breast cancer.

Metastatic human epidermal growth factor receptor 2 (HER2)-positive breast cancer is currently incurable. The primary goals of treatment are to prolong survival while optimizing quality of life. Several agents are now available in this setting, including neratinib, tucatinib, ado-trastuzumab emtansine, and trastuzumab deruxtecan. Neratinib in combination with capecitabine was recently approved for the treatment of adult patients with advanced or metastatic breast cancer who have received 2 or more prior anti-HER2-based regimens in the metastatic setting. Neratinib is an oral pan-HER inhibitor that binds covalently to the kinase site, providing irreversible binding. Phase 3 data showed that the combination of neratinib plus capecitabine improved progression-free survival vs lapatinib plus capecitabine. The duration of response was longer among patients in the neratinib arm. Neratinib plus capecitabine was also active against brain metastases associated with refractory, HER2-positive breast cancer, and this combination is listed in guidelines from the National Comprehensive Cancer Network for this indication. When combined with fulvestrant, neratinib demonstrated efficacy in patients with HER2-positive breast cancer, regardless of their hormone receptor status. Ongoing trials are evaluating the ability of neratinib to treat brain metastases, as well as the efficacy and safety of the triplet combination of neratinib, fulvestrant, and trastuzumab in this setting.

How to design preclinical studies in nanomedicine and cell therapy to maximize the prospects of clinical translation.

The clinical translation of promising products, technologies and interventions from the disciplines of nanomedicine and cell therapy has been slow and inefficient. In part, translation has been hampered by suboptimal research practices that propagate biases and hinder reproducibility. These include the publication of small and underpowered preclinical studies, suboptimal study design (in particular, biased allocation of experimental groups, experimenter bias and lack of necessary controls), the use of uncharacterized or poorly characterized materials, poor understanding of the relevant biology and mechanisms, poor use of statistics, large between-model heterogeneity, absence of replication, lack of interdisciplinarity, poor scientific training in study design and methods, a culture that does not incentivize transparency and sharing, poor or selective reporting, misaligned incentives and rewards, high costs of materials and protocols, and complexity of the developed products, technologies and interventions. In this Perspective, we discuss special manifestations of these problems in nanomedicine and in cell therapy, and describe mitigating strategies. Progress on reducing bias and enhancing reproducibility early on ought to enhance the translational potential of biomedical findings and technologies.

Near-Infrared Photochemoimmunotherapy by Photoactivatable Bifunctional Antibody-Drug Conjugates Targeting Human Epidermal Growth Factor Receptor 2 Positive Cancer.

Near-infrared photoimmunotherapy (NIR-PIT) is a new class of molecular targeted cancer therapy based on antibody-photoabsorber conjugates and NIR light irradiation. Recent studies have shown effective tumor control, including that of human epidermal growth factor receptor 2 (HER2)-positive cancer, by selective molecular targeting with NIR-PIT. However, the depth of NIR light penetration limits its use. Trastuzumab emtansine (T-DM1) is an antibody-drug conjugate consisting of the monoclonal antibody trastuzumab linked to the cytotoxic agent maytansinoid DM1. Here, we developed bifunctional antibody-drug-photoabsorber conjugates, T-DM1-IR700, that can work as both NIR-PIT and chemoimmunotherapy agents. We evaluated the feasibility of T-DM1-IR700-mediated NIR light irradiation by comparing the in vitro and in vivo cytotoxic efficacy of trastuzumab-IR700 (T-IR700)-mediated NIR light irradiation in HER2-expressing cells. T-IR700 and T-DM1-IR700 showed almost identical binding to HER2 in vitro and in vivo. Owing to the presence of internalized DM1 in the target cells, NIR-PIT using T-DM1-IR700 tended to induce greater cytotoxicity than that of NIR-PIT using T-IR700 in vitro. In vivo NIR-PIT using T-DM1-IR700 did not show a superior antitumor effect to NIR-PIT using T-IR700 in subcutaneous small-tumor models, which could receive sufficient NIR light. In contrast, NIR-PIT using T-DM1-IR700 tended to reduce the tumor volume and showed significant prolonged survival compared to NIR-PIT using T-IR700 in large-tumor models that could not receive sufficient NIR light. We successfully developed a T-DM1-IR700 conjugate that has a similar immunoreactivity to the parental antibody with increased cytotoxicity due to DM1 and potential as a new NIR-PIT agent for targeting tumors that are large and inaccessible to sufficient NIR light irradiation to activate the photoabsorber IR700.

Prolonged Response to HER2-Directed Therapy in a Patient With HER2-Amplified, Rapidly Progressive Metastatic Colorectal Cancer.

HER2 gene amplifications and activating mutations in the HER2 receptor tyrosine kinase are present in 4% of metastatic colorectal cancers (mCRCs). HER2-targeted therapy is not standard of care, although preclinical and clinical data suggest that patients with HER2 amplifications and/or HER2-activating mutations may benefit from HER2-directed therapy. HER2 amplifications and activating mutations have also been implicated in resistance to anti-epidermal growth factor receptor-based therapy. This report describes a patient with KRAS, NRAS, and BRAF wild-type mCRC who experienced disease progression on first-line treatment with FOLFIRI and cetuximab after only 5 months, and subsequently experienced progression on second-line treatment with capecitabine and oxaliplatin plus bevacizumab after 2 months with significant functional decline. Next-generation sequencing of the primary tumor identified HER2 amplification, and we were able to obtain trastuzumab-DM1 for off-label use. The patient had symptomatic clinical benefit from trastuzumab-DM1 and had radiographic disease control for 7 months. On progression, therapy was changed to trastuzumab and pertuzumab, but the patient's disease progressed 3 months later. Treatment with the trastuzumab-DM1 resulted in a sustained response that was longer than his prior responses in the first and second lines of treatment, with a dramatic improvement in the patient's functional status. This case represents the first report, to our knowledge, of successful single-agent treatment of HER2-amplifed CRC with trastuzumab-DM1. Clinical trials targeting patients with HER2-mutated and -amplified metastatic colon cancer are currently underway. Molecular insights from investigating HER2 activation and the impact of HER2-directed therapies in a wide variety of solid tumors will create the needed evidence base to more broadly inform patient care.

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.

Ado-trastuzumab emtansine: a HER2-positive targeted antibody-drug conjugate.

OBJECTIVE: To review the pharmacology, pharmacokinetics, efficacy, adverse effects, drug-drug interactions, dosage and administration, and formulary considerations for ado-trastuzumab emtansine. DATA SOURCES: Sources of information were identified through a PubMed search (1966 to June 2014) using the key terms ado-trastuzumab emtansine, trastuzumab-DM1, trastuzumab-MCC-DM1, and T-DM1. Other information was obtained from clinicaltrials.gov, product labeling, and press releases. STUDY SELECTION AND DATA EXTRACTION: All English-language clinical trials and abstracts evaluating ado-trastuzumab emtansine in humans were reviewed for inclusion. DATA SYNTHESIS: Overexpression or amplification of human epidermal growth factor receptor 2 (HER2) occurs in approximately 20% of breast cancers and is associated with more aggressive tumors and poorer prognosis in the absence of treatment. Although effective therapies for the initial management of HER2-positive metastatic breast cancer (MBC) exist, many patients will experience disease progression. Most second-line therapies are associated with either significant toxicities or limited improvements in overall survival (OS). Ado-trastuzumab emtansine is a HER2-positive directed antibody drug conjugate (ADC) approved in February 2013. In phase III clinical trials comparing the efficacy and safety of ado-trastuzumab emtansine with lapatinib-capecitabine or physician's choice, ado-trastuzumab emtansine had a better tolerability profile and improved progression-free survival compared with lapatinib-capecitabine or physician's choice and increased OS compared with lapatinib-capecitabine. CONCLUSION: Ado-trastuzumab emtansine is a novel ADC effective for HER2-positive MBC in patients previously treated with trastuzumab, lapatinib, and a taxane. Further studies will determine its use in the adjuvant and neoadjuvant setting and in combination with pertuzumab.

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.

Trastuzumab emtansine for the treatment of HER2-positive metastatic breast cancer.

Trastuzumab emtansine is an antibody-drug conjugate comprised of the receptor tyrosine-protein kinase erbB-2 (HER2) antibody trastuzumab, and a derivative of the cytostatic agent maytansinoid DM1, covalently linked by a thiol linker. The drug was developed in an attempt to overcome trastuzumab resistance in patients with HER2-positive breast carcinoma, but it is also of potential use in other HER2-positive cancers. The preclinical antitumor activity of trastuzumab emtansine was established in HER2-positive breast cancer cell lines and murine xenograft models. Preclinically, trastuzumab emtansine was efficacious in HER2-positive cells that were resistant to trastuzumab or lapatinib. Clinically, the drug is well tolerated in most patients, with a predictable pharmacokinetic profile and minimal systemic exposure to free cytotoxic DM1. Unlike with trastuzumab, cardiac toxicity has not been seen in patients receiving trastuzumab emtansine and less adverse events have been reported than with other chemotherapy regimens. Results from a number of phase II studies and early results from a phase III investigation (EMILIA) demonstrated response rates of 25-35% in patients with breast cancer who had previously received trastuzumab. Several phase II and III studies are under way investigating trastuzumab emtansine in combination with other regimens in patients with HER2-positive cancers.

Biological therapies in breast cancer: common toxicities and management strategies.

In recent years, a number of new molecules - commonly known as biological therapies - have been approved or are in late stages of regulatory evaluation for the treatment of advanced breast cancer. These innovative compounds have improved treatment efficacy and have probably contributed to the increase in survival length observed in some breast cancer subtypes. However, these agents are not deprived of toxicity, which can impair quality of life and may occasionally be life-threatening. In this article, we reviewed the most common toxicities associated with these drugs and provided a number of practical recommendations on their optimal clinical management.

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.

Preclinical and clinical pharmacokinetic/pharmacodynamic considerations for antibody-drug conjugates.

Antibody-drug conjugates (ADCs) represent a promising therapeutic modality for the clinical management of cancer. Here we discuss the clinical pharmacology and safety of ADCs that are either approved or in late stages of clinical development. We have taken examples of ADCs employing either DNA damaging payloads (such as calicheamicin) or tubulin depolymerizing agents (such as auristatins and maytansinoids) to discuss the impact of dose and dosage intervals on pharmacokinetics/pharmacodynamics (PK/PD) and safety of ADCs. We also discuss the development of PK/PD models that were validated using preclinical and clinical data from two approved ADCs (ado-trastuzumab emtansine (T-DM1, Kadcyla™) and brentuximab vedotin (SGN-35, Adcetris™). These models could be used to predict clinical efficacious doses of ADCs.

[Antibody-drug conjugates in oncology: from the concept to trastuzumab emtansine (T-DM1)]. / Les anticorps conjugués en oncologie : du concept au trastuzumab emtansine (T-DM1).

Trastuzumab emtansine (T-DM1) is an antibody-drug conjugate (ADC) which associates the selective intracellular targeting of the cytotoxic agent, DM1 (maytansine derivative) to the antitumor activity of trastuzumab. T-DM1 targets the epidermal growth factor receptor 2 (HER2), highly expressed in the most aggressive forms of breast cancer. Current standard of care in HER2-positive advanced or metastatic breast cancers has its limitations, particularly after progression on HER2-targeted approved therapies. T-DM1 showed a significant antitumor activity in vitro and in vivo, and in experimental models resistant to HER2-targeted agents. Phase I and II studies showed that the maximum tolerated dose for T-DM1 is 3.6 mg/kg given intravenously every three weeks. At this recommended dose, T-DM1 provided objective tumor responses and favourable safety profile. A phase II randomised study, evaluating T-DM1 in first line vs trastuzumab plus docetaxel, the current standard of care in advanced or metastatic breast cancers, showed improved tolerability and efficacy. Recently, the results of EMILIA, a phase III randomised study assessing, after prior treatment with trastuzumab and a taxane, the efficacy and the safety of T-DM1 vs lapatinib plus capecitabine, confirmed the therapeutic benefit. T-DM1 appears to be an effective therapeutic option to treat patients with HER2-positive metastatic breast cancer.

ADME of antibody-maytansinoid conjugates.

The concept of treating cancer with antibody-drug conjugates (ADCs) has gained momentum with the favorable activity and safety of trastuzumab emtansine (T-DM1), SAR3419, and lorvotuzumab mertansine (IMGN901). All three ADCs utilize maytansinoid cell-killing agents which target tubulin and suppress microtubule dynamics. Each ADC utilizes a different optimized chemical linker to attach the maytansinoid to the antibody. Characterizing the absorption, distribution, metabolism, and excretion (ADME) of these ADCs in preclinical animal models is important to understanding their efficacy and safety profiles. The ADME properties of these ADCs in rodents were inferred from studies with radio-labeled ADCs prepared with nonbinding antibodies since T-DM1, SAR3419, IMGN901 all lack cross-reactivity with rodent antigens. For studies exploring tumor localization and activation in tumor-bearing mice, tritium-labeled T-DM1, SAR3419, and IMGN901 were utilized. The chemical nature of the linker was found to have a significant impact on the ADME properties of these ADCs-particularly on the plasma pharmacokinetics and observed catabolites in tumor and liver tissues. Despite these differences, T-DM1, SAR3419, and IMGN901 were all found to facilitate efficient deliveries of active maytansinoid catabolites to the tumor tissue in mouse xenograft models. In addition, all three ADCs were effectively detoxified during hepatobiliary elimination in rodents.

Catabolic fate and pharmacokinetic characterization of trastuzumab emtansine (T-DM1): an emphasis on preclinical and clinical catabolism.

Trastuzumab emtansine (T-DM1) is an antibody-drug conjugate in clinical development for the treatment of human epidermal growth factor receptor 2 (HER2)-positive cancers. Herein, we describe a series of studies to assess T-DM1 absorption, distribution, metabolism, and excretion (ADME) in rats as well as to assess human exposure to T-DM1 catabolites. Following administration of unlabeled and radiolabeled T-DM1 in female Sprague Dawley rats as a single dose, plasma, urine, bile and feces were assessed for mass balance, profiling and identification of catabolites. In rats, the major circulating species in plasma was T-DM1, while DM1 concentrations were low (1.08 to 15.6 ng/mL). The major catabolites found circulating in rat plasma were DM1, [N-maleimidomethyl] cyclohexane-1- carboxylate-DM1 (MCC-DM1), and Lysine-MCC-DM1. These catabolites identified in rats were also detected in plasma samples from patients with HER2-positive metastatic breast cancer who received single-agent T-DM1 (3.6 mg/kg every 3 weeks) in a phase 2 clinical study. There was no evidence of tissue accumulation in rats or catabolite accumulation in human plasma following multiple dosing. In rats, T-DM1 was distributed nonspecifically to the organs without accumulation. The major pathway of DM1-containing catabolite elimination in rats was the fecal/biliary route, with up to 80% of radioactivity recovered in the feces and 50% in the bile. The rat T-DM1 ADME profile is likely similar to the human profile, although there may be differences since trastuzumab does not bind the rat HER2- like receptor. Further research is necessary to more fully understand the T-DM1 ADME profile in humans.