Efficacy and safety of biosimilar trastuzumab (CT-P6) in routine clinical practice in the Republic of Korea: a real-world post-marketing surveillance study

BACKGROUND

The trastuzumab biosimilar CT-P6 is approved for human epidermal growth factor receptor 2 (HER2)-positive early breast cancer (EBC), metastatic breast cancer (MBC), and metastatic gastric cancer (MGC). The objective of this post-marketing surveillance (PMS) study was to evaluate the real-world safety and effectiveness of CT-P6 in patients with HER2-positive cancers.

RESEARCH DESIGN AND METHODS

This open-label, observational, prospective, PMS study collected data via investigator surveys from 35 centers in the Republic of Korea (5 October 2018-4 October 2022). Eligible patients with HER2-positive EBC, MBC, or MGC started CT-P6 treatment during routine clinical practice, followed by 1-year observation. Evaluations included adverse events (AEs), adverse drug reactions (ADRs), and effectiveness.

RESULTS

Safety was analyzed in 642 patients (494 EBC, 94 MBC, 54 MGC). Overall, 325 (50.6%) patients experienced 1316 AEs, and 550 ADRs occurred in 199 (31.0%) patients. Unexpected ADRs occurred in 62 (9.7%) patients. Unexpected ADRs and ADRs of special interest did not raise any new safety signals. Among trastuzumab-naïve patients, 34/106 (32.1%) with EBC achieved pathological complete response; 30/74 (40.5%) MBC and 24/49 (49.0%) MGC patients achieved complete or partial response.

CONCLUSIONS

In a real-world setting, CT-P6 demonstrated safety and efficacy findings consistent with previous CT-P6 studies.

Trastuzumab in breast cancer treatment: the Era of biosimilars

BACKGROUND

The discovery of trastuzumab as anti-HER2 therapy markedly improved disease control and the survival rates of patients with HER2+ breast cancer. However, as trastuzumab is considered a complex molecule, the cost of production is usually elevated, which significantly affects health budgets and limits the treatment access for patients who live in underdeveloped countries. Recently, trastuzumab production became more accessible and sustainable due to the patents' expiration, allowing biosimilar versions of trastuzumab to be developed.

OBJECTIVE

Our main goal was to shed more light on the uses of biosimilars in breast cancer treatment, emphasizing trastuzumab.

METHOD

An integrative review was carried out in the PubMed, Scielo, Web of Science, and SCOPUS databases using the terms "biosimilar," "breast cancer," "monoclonal antibody," and "trastuzumab." The time range included scientific articles published from 2015 to 2021.

RESULTS AND DISCUSSION

The bibliographic survey showed the complexities in biological medicine manufacturing and how the monoclonal antibody's therapy with trastuzumab improved the patients' life expectancy, revolutionizing HER2+ breast cancer treatment. Nonetheless, despite its benefits, trastuzumab generates certain restrictions, especially from the economic perspective. Trastuzumab biosimilars have high selectivity and rarely cause adverse effects compared to conventional chemotherapy.

CONCLUSION

This study shows that trastuzumab biosimilars improve patients' accessibility to breast cancer treatment through a safe and effective therapy compared to the drug reference.

Clinical benefit of treatment after trastuzumab emtansine for HER2-positive metastatic breast cancer: a real-world multi-centre cohort study in Japan (WJOG12519B)

BACKGROUND

Trastuzumab emtansine (T-DM1) treatment for human epidermal growth factor receptor-2 (HER2)-positive metastatic breast cancer after taxane with trastuzumab and pertuzumab is standard therapy. However, treatment strategies beyond T-DM1 are still in development with insufficient evidence of their effectiveness. Here, we aimed to evaluate real-world treatment choice and efficacy of treatments after T-DM1 for HER2-positive metastatic breast cancer.

METHODS

In this multi-centre retrospective cohort study involving 17 hospitals, 325 female HER2-positive metastatic breast cancer patients whose post-T-DM1 treatment began between April 15, 2014 and December 31, 2018 were enrolled. The primary end point was the objective response rate (ORR) of post-T-DM1 treatments. Secondary end points included disease control rate (DCR), progression-free survival (PFS), time to treatment failure (TTF), and overall survival (OS).

RESULTS

The median number of prior treatments of post-T-DM1 treatment was four. The types of post-T-DM1 treatments included (1) chemotherapy in combination with trastuzumab and pertuzumab (n = 102; 31.4%), (2) chemotherapy concomitant with trastuzumab (n = 78; 24.0%), (3), lapatinib with capecitabine (n = 63; 19.4%), and (4) others (n = 82; 25.2%). ORR was 22.8% [95% confidence interval (CI): 18.1-28.0], DCR = 66.6% (95% CI 60.8-72.0), median PFS = 6.1 months (95% CI 5.3-6.7), median TTF = 5.1 months (95% CI 4.4-5.6), and median OS = 23.7 months (95% CI 20.7-27.4).

CONCLUSION

The benefits of treatments after T-DM1 are limited. Further investigation of new treatment strategies beyond T-DM1 is awaited for HER2-positive metastatic breast cancer patients.

Tolerability and toxicity of trastuzumab or trastuzumab + lapatinib in older patients: a sub-analysis of the ALTTO trial (BIG 2-06; NCCTG (Alliance) N063D)

PURPOSE

Little is known about the use of trastuzumab or trastuzumab + lapatinib in older patients. We have performed a sub-analysis of the Adjuvant Lapatinib And/Or Trastuzumab Treatment Optimisation (ALTTO) trial focused on toxicity and treatment completion of both regimens in older patients (≥ 65 years old) METHODS: The ALTTO trial randomised 8381 patients with early HER2-positive BC in 4 arms. Eligible patients for this study were those having received at least one dose of assigned treatment in either the trastuzumab or trastuzumab + lapatinib arms. Treatment completion was evaluated through the rate of temporary treatment interruptions, permanent treatment discontinuations and lapatinib dose reductions. Toxicity was evaluated via a selected subset of adverse events of interest (AEI). Risk factors for both treatment completion outcomes and toxicity were investigated, including comorbidities and use of 5 or more co-medications at randomization.

RESULTS

A total of 430 patients ≥ 65 year were eligible. Median age was 68 (range 65-80). In comparison with the younger cohort, older patients had a significantly higher number of comorbidities at randomization (p < 0.001). Treatment completion outcomes were worse, particularly in the trastuzumab + lapatinib arm. Adverse events of interest were likewise more common in the trastuzumab + lapatinib arm with higher AEI rates (63.4% in younger vs 78.0% in older, p < 0.001). Concomitant chemotherapy was associated with worse treatment completion outcomes among older patients.

CONCLUSION

Trastuzumab plus lapatinib was significantly more toxic among older patients and had worse treatment completion. Trastuzumab was generally well tolerated.

Heavy chain dimers stabilized by disulfide bonds are required to promote in vitro assembly of trastuzumab

BACKGROUND

Monoclonal antibodies (mAbs) and their derivatives have become one of the most important classes of therapeutic drugs. Their multiple applications increased the interest for understanding their complex structure. In vivo, animal cells are able to fold mAbs correctly (Song et al, J Biosci Bioeng 110:135-40, 2010), whereas previous in vitro approaches were scarce and mostly unsuccessful.

RESULTS

In this work, we compared in vitro assembly characteristics of trastuzumab, produced either by A) physical separation and refolding of its sub-units or B) direct joining of individually produced heavy and light chains. Native and denatured structures of trastuzumab were determined by SEC-HPLC, HIC-HPLC and SDS-PAGE.

CONCLUSIONS

Our results demonstrate the requirement of correctly folded HC, forming disulfide-bonded dimers, in order to form a fully functional mAb. Otherwise, the unfolded HC tend to precipitate. We were able to assemble trastuzumab in this fashion by only mixing them to LC in pH-buffered conditions, while monomeric HC structure was too unstable to render a functional mAb. This approach has been used in the generation of homogeneous ADC, with results pending to be published.

Systemic Treatments in Pregnancy-Associated Breast Cancer

Available data on systemic treatments in pregnancy-associated breast cancer (PABC) is reviewed in this section. These treatments include chemotherapy, endocrine therapy (ET), small molecule inhibitors, monoclonal antibodies against human epidermal growth factor receptor 2 (EGFR-2) also known as HER2; and human epidermal growth factor receptor 3 (EGFR-3), also known as HER3.In local disease, systemic treatment can be delivered as neoadjuvant (before surgery) or adjuvant (after surgery) treatment. In metastatic disease, systemic therapy is the main modality of treatment.Approach to PABC is based on available data in the general population, limited only by safety issues for use of medications during gestation and lactation. Therefore, treatments are similar to non-PABC patients while trying to minimize the risk to the fetus. Available data on different chemotherapies, anti-HER2 monoclonal antibodies, ET and small molecule inhibitors are discussed in detail.

A continuous-time multistate Markov model to describe the occurrence and severity of diarrhea events in metastatic breast cancer patients treated with lumretuzumab in combination with pertuzumab and paclitaxel

PURPOSE

To inform lumretuzumab and pertuzumab dose modifications in order to decrease the incidence, severity, and duration of the diarrhea events in metastatic breast cancer patients treated with a combination therapy of lumretuzumab (anti-HER3) in combination with pertuzumab (anti-HER2) and paclitaxel using quantitative clinical pharmacology modeling approaches.

METHODS

The safety and pharmacokinetic (PK) data from three clinical trials (lumretuzumab monotherapy n = 47, pertuzumab monotherapy n = 78, and the combination therapy of lumretuzumab, pertuzumab and paclitaxel n = 35) were pooled together to develop a continuous-time discrete states Markov model describing the dynamics of the diarrhea events.

RESULTS

The model was able to capture the time course of different severities of diarrhea reasonably well. The effect of lumretuzumab and pertuzumab was well described by an E_max function indicating an increased rate of transition from moderate to mild or more severe diarrhea with higher doses. The concentration needed to trigger or worsen diarrhea episodes was estimated to be 120-fold lower in combination therapy compared to monotherapy, suggesting strong synergy between the two monoclonal antibodies. The prophylactic effect of loperamide in a subset of patients was also well captured by the model with a clear tendency to reduce the occurrence of diarrhea events.

CONCLUSIONS

This work shows that PK-toxicity modeling provides insight into how the severity of key adverse events evolves over time and highlights the potential use to support decision making in drug development.

A novel way to manage trastuzumab cardiotoxicity

PURPOSE

Trastuzumab is the most widely prescribed anti-HER2 humanized monoclonal antibody. Cardiac toxicity is the only limiting toxicity of trastuzumab and it is of particular concern in patients with complete response, since the drug needs to be stopped, with a risk of disease relapse. To date, no pharmacological data on trastuzumab cardiotoxicity in patients have been made available. Here, we provide proof of concept, demonstrating that it was possible to prevent trastuzumab-induced cardiotoxicity by modifying the drug administration schedule.

METHODS

In this paper, we report the case of a patient with metastatic breast cancer responding to trastuzumab, who developed severe cardiac toxicity twice using a 3-weekly regimen. Considering preclinical pharmacological data on trastuzumab cardiotoxicity, we hypothesized that a weekly schedule of trastuzumab with lower peaks of serum concentration could be safe while remaining efficient. With the patient's consent, we started a weekly combination of carboplatin (AUC2) and trastuzumab (2 mg/kg) with close monitoring of trastuzumab concentrations.

RESULTS

We successfully controlled the disease for an additional 6 months with relevant trough concentrations of trastuzumab of around 50 mg/L. Another important aspect is that, with this weekly schedule, we observed no cardiac toxicity, and the left ventricular ejection fraction remained stabilized, at over 50%.

CONCLUSIONS

Trastuzumab is the most widely prescribed anti-HER2 monoclonal antibody for the treatment of HER2 metastatic breast cancer, and it is the only drug that has been approved for the treatment of localized HER2 breast cancer, 1-year treatment being required after surgery. In case of cardiac toxicity, particularly in women over 60 years of age, a weekly regimen with lower peaks of concentration could be an alternative to the standard 3-weekly regimen.

Adverse Events of Trastuzumab Emtansine (T-DM1) in the Treatment of HER2-Positive Breast Cancer Patients

The human epidermal growth factor receptor 2 (HER2) is commonly associated with poor prognosis and is overexpressed in approximately 15-20% of all breast cancers. The introduction of HER2-targeted therapies led to significant improvement in the prognosis of patients with HER2-positive breast cancer, for both early and advanced disease. These targeted therapies include the antibodies trastzumab and pertuzumab, the tyrosine kinase inhibitor lapatinib, and the antibody-drug conjugate trastuzumab emtansine (T-DM1). T-DM1 combines the anti-tumor activity of trastuzumab with that of DM1, a highly potent derivative of the anti-microtubule agent maytansine, resulting in increased anti-tumor activity. Notably, this agent has been demonstrated to be safe and is associated with low toxicity rates. However, maytansinoid, the cytotoxic component of T-DM1, does have the potential to induce various adverse events, particularly radiation necrosis, when used in combination with stereotactic radiosurgery. In this review, we aimed to summarize the current literature regarding T-DM1 safety and toxicity, with special emphasis on the existing landmark studies.

Synthesis and application of magnetite dextran-spermine nanoparticles in breast cancer hyperthermia

Cancer treatment has been very challenging in recent decades. One of the most promising cancer treatment methods is hyperthermia, which increases the tumor temperature (41-45 °C). Magnetic nanoparticles have been widely used for selective targeting of cancer cells. In the present study, magnetic dextran-spermine nanoparticles, conjugated with Anti-HER2 antibody to target breast cancer cells were developed. The magnetic dextran-spermine nanoparticles (DMNPs) were prepared by ionic gelation, followed by conjugation of antibody to them using EDC-NHS method. Then the Prussian blue method was used to estimate the targeting ability and cellular uptake. Cytotoxicity assay by MTT showed that antibody-conjugated MNPs (ADMNPs) have no toxic effect on SKBR3 and human fibroblast cells. Finally, the hyperthermia was applied to show that synthesized ADMNPs, could increase the cancer cells temperature up to 45 °C and kill most of them without affecting normal cells. These observations proved that Anti-HER2 conjugated magnetic dextran-spermine nanoparticles can target and destroy cancer cells and are potentially suitable for cancer treatment.

[Novel pharmaceutical treatment approaches for gastric cancer]

This review article delineates novel approaches for the pharmaceutical treatment of gastric cancer. A newly developed molecular classification of gastric cancer based on histology, genetic, epigenetic and proteomic characteristics has evolved. It provides a road map for development of new drugs and combinations as well as for patient stratification in clinical research and it is expected to be introduced into clinical practice in the near future. Anti-HER2 targeted treatment is a validated strategy for treatment of metastatic gastric cancer and is now also being studied in the perioperative setting to increase response rates and ultimately survival in patients undergoing curative surgery; however, the resistance mechanisms of HER2-targeted treatment are poorly understood and optimal patient selection remains challenging. Targeting angiogenesis is a novel concept in the management of advanced gastric cancer. Ramucirumab is an antibody against vascular endothelial growth factor receptor 2 (VEGFR2) and prolongs survival in second-line treatment as a monotherapy and also in combination with paclitaxel; however, biomarkers for selection of patients who particularly benefit from antiangiogenic treatment are still lacking. Immune checkpoint blockade and inhibition of cancer stem cell targets are two emerging principles for the medicinal treatment of gastric cancer. Large-scale international studies for evaluation of these treatment approaches are ongoing. In summary, promising biology-based treatment strategies are evolving; however, tumor heterogeneity, which is an inherent feature of gastric cancer is a particular challenge for the development of targeted medications and a personalized treatment.

Anti-HER2 Therapy Beyond Second-Line for HER2-Positive Metastatic Breast Cancer: A Short Review and Recommendations for Several Clinical Scenarios from a Spanish Expert Panel

BACKGROUND

The aim of this project was to provide an expert opinion regarding anti-human epidermal growth factor receptor 2 (HER2) therapy beyond second-line treatment of metastatic breast cancer (mBC).

METHODS

A group of experts discussed specific issues concerning anti-HER2 therapy in late-line settings in mBC.

RESULTS

Trastuzumab emtansine (T-DM1) or dual HER2 blockade appeared to be good options for HER2-positive mBC after ≥ 2 HER2-targeted therapies. Once an objective response has been achieved with anti-HER2-containing therapy, the anti-HER2 agent can be continued until progression of the disease, unacceptable toxicity or patient decision. mBC treated with ≥ 3 consecutive lines of anti-HER therapy, ≥ 1 being a dual HER2 blockade and with early progression of disease during a fourth or later-line treatment, are clinically resistant to anti-HER therapy. For progression of metastasis in the brain after anti-HER2 therapy, lapatinib and chemotherapy appear to be a good alternative after best local treatment.

CONCLUSIONS

Further clinical trials are needed to provide valuable knowledge about the best treatment options in the later settings of mBC.

Novel antibody drug conjugates containing exatecan derivative-based cytotoxic payloads

Trastuzumab conjugates consisting of exatecan derivatives were prepared and their biological activities and physicochemical properties were evaluated. The ADCs showed strong efficacy and a low aggregation rate. The exatecan derivatives were covalently connected via a peptidyl spacer (Gly-Gly-Phe-Gly), which is assumed to be stable in circulation, and were cleaved by lysosomal enzymes following ADC internalization into tumor tissue. These anti-HER2 ADCs exhibited a high potency, specifically against HER2-positive cancer cell lines in vitro. The ADCs, bearing exatecan derivatives which have more than two methylene chains, exhibited superior cytotoxicity. It was speculated that steric hindrance of the cleavable amide moiety could be involved in the drug release. The adequate alkyl lengths of exatecan derivatives (13, 14, 15) were from two to four in terms of aggregation rate. The ADC having a hydrophilic moiety showed good efficacy in a HER2-positive and Trastuzumab-resistant breast carcinoma cell model in mice.

Biofunctional quantum dots as fluorescence probe for cell-specific targeting

We describe here the synthesis, characterization, bioconjugation, and application of water-soluble thioglycolic acid TGA-capped CdTe/CdS quantum dots (TGA-QDs) for targeted cellular imaging. Anti-human epidermal growth factor receptor 2 (HER2) antibodies were conjugated to TGA-QDs to target HER2-overexpressing cancer cells. TGA-QDs and TGA-QDs/anti-HER2 bioconjugates were characterized by fluorescence and UV-Vis spectroscopy, X-ray diffraction (XRD), hydrodynamic sizing, electron microscopy, and gel electrophoresis. TGA-QDs and TGA-QDs/anti-HER2 were incubated with cells to examine cytotoxicity, targeting efficiency, and cellular localization. The cytotoxicity of particles was measured using an MTT assay and the no observable adverse effect concentration (NOAEC), 50% inhibitory concentration (IC50), and total lethal concentration (TLC) were calculated. To evaluate localization and targeting efficiency of TGA-QDs with or without antibodies, fluorescence microscopy and flow cytometry were performed. Our results indicate that antibody-conjugated TGA-QDs are well-suited for targeted cellular imaging studies.