[Pertuzumab (Perjeta®) approval in HER2-positive metastatic breast cancers]

Encapsulation and release of calcein from herceptin-conjugated eLiposomes

Achieving an optimal therapeutic level is crucial in effectively eradicating cancer cells during treatment. However, conventional chemotherapy-associated systemic administration of anticancer agents leads to many side effects. To achieve the desired control over the target site, active targeting of HER2-positive breast cancer cells can be achieved by conjugating liposomal vesicles with Human Epidermal growth factor Receptor 2 (HER2) and inducing release of the encapsulated drug using ultrasound. To further enhance the delivery efficiency, nanoemulsion droplets exhibiting responsiveness to low-frequency ultrasound are encapsulated within these lipid vesicles. In this study, we prepared four different liposomal formulations, namely pegylated liposomes, emulsion liposomes (eLiposomes), HER-conjugated liposomes, and HER-conjugated eLiposomes, each loaded with calcein and subjected to a thorough characterization process. Their sizes, phospholipid concentration, and amount of antibody conjugation were compared and analyzed. Cryogenic transmission electron microscopy was used to confirm the encapsulation of nanoemulsion droplets within the liposomes. The drug-releasing performance of Herceptin-conjugated eLiposomes was found to surpass that of other liposomal formulations with a notably higher calcein release and established it as a highly effective nanocarrier. The study showcases the efficacy of calcein-loaded and Herceptin-conjugated eLiposomes, which demonstrate rapid and efficient drug release among other liposomal formulations when subjected to ultrasound. This discovery paves the way for a more targeted, efficient, and humane approach to cancer therapy.

Homodimer 99mTc-HYNIC-E(SSSLTVPWY)2 peptide improved HER2-overexpressed tumor targeting and imaging

We hypothesized that a novel design of the LTVPWY (LY) peptide might exhibit a great potential for improving binding affinity and targeting HER2-overexpressed tumors. Hence, new dimer construction of ^99mTc-labeled LY [^99mTc-HYNIC-E(SSSLTVPWY)₂] (^99mTc-DLY) was introduced. Afterward, a head-to-head comparison of in vitro and in vivo experiments was performed between ^99mTc-DLY and ^99mTc-HYNIC-SSSLTVPWY as the monomer analog. The blocking dosage of trastuzumab reduced the uptake of the dimer about 20% more efficiently than the monomer in the SKOV-3 cell line. A twofold increase in competitive binding affinity and biological half-life was observed for ^99mTc-DLY. The ovarian-tumor-bearing mice were detected with high contrast where the tumor-to-muscle ratio of ^99mTc-DLY was notably increased about 40% using a gamma camera. The biodistribution experiment revealed an approximately 10% enhancement in tumor/blood, tumor/muscle, and tumor/bone ratios for the dimer. More rapid blood clearance was another achievement of the homodimer design. Overall, ^99mTc-DLY successfully affected the pharmacokinetics and consequently the visualization of HER2-overexpressing tumors.

A Review on Nanocarrier Mediated Treatment and Management of Triple Negative Breast Cancer: A Saudi Arabian Scenario

People have continued to be petrified by the devastating effects of cancer for decades and thus a pursuit for developing anticancer agents have seen an ever-increasing trend in the past few decades. Globally, breast cancer is the most common malignancy in women and the second most common cause of cancer-related deaths. In Saudi Arabia, breast cancer is the most common type of cancer among women, constituting almost 14.2% of the total cancer burden. Triple-negative breast cancer (TNBC) is a subtype of breast cancer, which is a pathologically diverse disease of higher grade characterized by the absence of the estrogen receptor (ER), the progesterone receptor (PR), and the human epidermal growth factor receptor 2 (HER2) expressions. Despite the considerable advancements achieved in the therapeutic management of cancer, TNBC remains an unbeatable challenge, which requires immediate attention as it lacks conventional targets for treatment, leading to a poor clinical prognosis. The present research goals are directed toward the development and implementation of treatment regimens with enhanced bioavailability, targetability, minimized systemic toxicity, and improved outcomes of treatment options. The present treatment and management scenario of TNBC continues to provoke oncologists as well as nanomedical scientists to develop novel and efficient nanotherapies. Lately, scientific endeavors have addressed the importance of enhanced availability and targeted cellular uptake with minimal toxicity, which are achieved by the application of nano drug-carriers. This review intends to summarize the incidence rates of TNBC patients, the importance of nanotherapeutic options for patients suffering from TNBC, the identification of promising molecular targets, and challenges associated with the development of targeted nanotherapeutics with special reference to the Saudi Arabian context.

ERBB Signaling Pathway in Cancer Stem Cells

The epidermal growth factor receptor (EGFR) was first tyrosine kinase receptor linked to human cancers. EGFR or ERBB1 is a member of ERBB subfamily, which consists of four type I transmembrane receptor tyrosine kinases, ERBB1, 2, 3 and 4. ERBBs form homo/heterodimers after ligand binding except ERBB2 and consequently becomes activated. Different signal pathways, such as phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT), RAS/RAF/MEK/ERK, phospholipase Cγ and JAK-STAT, are triggered by ERBB activation. Since ERBBs, through these pathways, regulate stemness and differentiation of cancer stem cells (CSCs), their roles in CSC tumorigenicity have extensively been investigated. The hyperactivation of ERBBs and its downstream pathways stimulated by either genetic and/or epigenetic factors are frequently described in many types of human cancers. Their dysregulations make cells acquiring CSC characters such as survival, tumorigenicity and stemness. Because of the roles in tumor growth and progress, ERBBs are considered to be one of the drug targets as cancer treatment strategy. In this chapter, we will summarize the structure, function and roles of ERBB subfamily along with their relative pathways regulating the stemness and tumorigenicity of CSCs. Finally, we will discuss the targeting therapy strategies of cancer along with ERBBs in addition to some challenges and future perspectives.

Development of a Virus-Like Particle-Based Anti-HER2 Breast Cancer Vaccine

To develop a human epidermal growth factor receptor-2 (HER2)-specific cancer vaccine, using a plant virus-like particle (VLP) platform. Copper-free click chemistry and infusion encapsulation protocols were developed to prepare VLPs displaying the HER2-derived CH401 peptide epitope, with and without Toll-like receptor 9 (TLR9) agonists loaded into the interior cavity of the VLPs; Physalis mottle virus (PhMV)-based VLPs were used. After prime-boost immunization of BALB/c mice through subcutaneous administration of the vaccine candidates, sera were collected and analyzed by enzyme-linked immunosorbent assay (ELISA) for the CH401-specific antibodies; Th1 vs. Th2 bias was determined by antibody subtyping and splenocyte assay. Efficacy was assessed by tumor challenge using DDHER2 tumor cells. We successful developed two VLP-based anti-HER2 vaccine candidates-PhMV-CH401 vs. CpG-PhMV-CH401; however, the addition of the CpG adjuvant did not confer additional immune priming. Both VLP-based vaccine candidates elicited a strong immune response, including high titers of HER2-specific immunoglobulins and increased toxicity of antisera to DDHER2 tumor cells. DDHER2 tumor growth was delayed, leading to prolonged survival of the vaccinated vs. naïve BALB/C mice. The PhMV-based anti-HER2 vaccine PhMV-CH401, demonstrated efficacy as an anti-HER2 cancer vaccine. Our studies highlight that VLPs derived from PhMV are a promising platform to develop cancer vaccines.

Evolution of overall survival and receipt of new therapies by subtype among 20 446 metastatic breast cancer patients in the 2008-2017 ESME cohort

Background

Treatment strategies for metastatic breast cancer (MBC) have made great strides over the past 10 years. Real-world data allow us to evaluate the actual benefit of new treatments. ESME (Epidemio-Strategy-Medico-Economical)-MBC, a nationwide observational cohort (NCT03275311), gathers data of all consecutive MBC patients who initiated their treatment in 18 French Cancer Centres since 2008.

Patients and methods

We evaluated overall survival (OS) in the whole cohort (N = 20 446) and among subtypes: hormone receptor positive, human epidermal growth factor 2 negative (HR+/HER2−; N = 13 590), HER2+ (N = 3919), and triple-negative breast cancer (TNBC; N = 2937). We performed multivariable analyses including year of MBC diagnosis as one of the covariates, to assess the potential OS improvement over time, and we described exposure to newly released drugs at any time during MBC history by year of diagnosis (YOD).

Results

The median follow-up of the whole cohort was 65.5 months (95% CI 64.6-66.7). Year of metastatic diagnosis appears as a strong independent prognostic factor for OS [Year 2016 HR 0.89 (95% CI 0.82-0.97); P = 0.009, using 2008 as reference]. This effect is driven by the HER2+ subcohort, where it is dramatic [Year 2016 HR 0.52 (95% CI 0.42-0.66); P < 0.001, using 2008 as reference]. YOD had, however, no sustained impact on OS among patients with TNBC [Year 2016 HR 0.93 (95% CI 0.77-1.11); P = 0.41, using 2008 as reference] nor among those with HR+/HER2– MBC [Year 2016 HR 1.02 (95% CI 0.91-1.13); P = 0.41, using 2008 as reference]. While exposure to newly released anti-HER2 therapies appeared very high (e.g. >70% of patients received pertuzumab from 2016 onwards), use of everolimus or eribulin was recorded in less than one-third of HR+/HER2– and TNBC cohorts, respectively, whatever YOD.

Conclusion

OS has dramatically improved among HER2+ MBC patients, probably in association with the release of several major HER2-directed therapies, whose penetrance was high. This trend was not observed in the other subtypes, but the impact of CDK4/6 inhibitors cannot yet be assessed.

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OS of HER2+ MBC patients keeps improving over time [Year 2016 HR 0.52 (95% CI 0.42-0.66); P < 0.001, using 2008 as reference].

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This effect seems timely related to the release of drugs demonstrated to improve survival in clinical trials.

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OS gains observed in real life among HER2+ MBC patients are at least equivalent to those observed in clinical trials.

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YOD had no sustained impact on OS among patients with TNBC and luminal MBC.

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The impact of CDK4/6 inhibitors cannot yet be assessed in this cohort.

Heterologous Prime-Boost Enhances the Antitumor Immune Response Elicited by Plant-Virus-Based Cancer Vaccine

New cancer vaccine strategies are required to vanquish the self-tolerance and elicit robust immune responses against tumor-associated antigens and/or neoantigens. Contemporary approaches in nanomedicine center on the use of a single nanocarrier modified with multiple copies of multiple different functional domains, e.g., epitopes for vaccines. Therefore, we set out to develop a combinatorial approach toward the next-generation concept of epitope delivery: a prime-boost strategy in which the same epitope is delivered using different nanocarriers. We tested this concept in the setting of HER2⁺ breast cancer. We synthesized HER2-based cancer vaccines using three icosahedral plant viruses as carriers and evaluated the immune response as a result of repetitive, homologous immunization using BALB/c mice. Two of the vaccines induced a Th2-predominant response and the other a Th1-predominant response. To enhance the immunogenicity of the vaccines, we developed a heterologous prime-boost strategy with each of the vaccines administered only once, yielding higher titers of HER2-specific immunoglobulins and increasing the toxicity of the antisera toward cancer cells. The prime-boost also induced a Th1-predominant response. An in vivo tumor challenge showed that the prime-boost regimen reduced tumor growth and improved survival in mice. This novel strategy to elicit robust immune responses against weakly immunogenic antigens in principle could be broadly applicable to cancers and other diseases.

Virus-like particle display of HER2 induces potent anti-cancer responses

Overexpression of human epidermal growth factor receptor-2 (HER2) occurs in 20–30% of invasive breast cancers. Monoclonal antibody therapy is effective in treating HER2-driven mammary carcinomas, but its utility is limited by high costs, side effects and development of resistance. Active vaccination may represent a safer, more effective and cheaper alternative, although the induction of strong and durable autoantibody responses is hampered by immune-tolerogenic mechanisms. Using a novel virus-like particle (VLP) based vaccine platform we show that directional, high-density display of human HER2 on the surface of VLPs, allows induction of therapeutically potent anti-HER2 autoantibody responses. Prophylactic vaccination reduced spontaneous development of mammary carcinomas by 50%-100% in human HER2 transgenic mice and inhibited the growth of HER2-positive tumors implanted in wild-type mice. The HER2-VLP vaccine shows promise as a new cost-effective modality for prevention and treatment of HER2-positive cancer. The VLP platform may represent an effective tool for development of vaccines against other non-communicable diseases.

Proof of concept study with an HER-2 mimotope anticancer vaccine deduced from a novel AAV-mimotope library platform

Background: Anticancer vaccines could represent a valuable complementary strategy to established therapies, especially in settings of early stage and minimal residual disease. HER-2 is an important target for immunotherapy and addressed by the monoclonal antibody trastuzumab. We have previously generated HER-2 mimotope peptides from phage display libraries. The synthesized peptides were coupled to carriers and applied for epitope-specific induction of trastuzumab-like IgG. For simplification and to avoid methodological limitations of synthesis and coupling chemistry, we herewith present a novel and optimized approach by using adeno-associated viruses (AAV) as effective and high-density mimotope-display system, which can be directly used for vaccination. Methods: An AAV capsid display library was constructed by genetically incorporating random peptides in a plasmid encoding the wild-type AAV2 capsid protein. AAV clones, expressing peptides specifically reactive to trastuzumab, were employed to immunize BALB/c mice. Antibody titers against human HER-2 were determined, and the isotype composition and functional properties of these were tested. Finally, prophylactically immunized mice were challenged with human HER-2 transfected mouse D2F2/E2 cells. Results: HER-2 mimotope AAV-vaccines induced antibodies specific to human HER-2. Two clones were selected for immunization of mice, which were subsequently grafted D2F2/E2 cells. Both mimotope AAV clones delayed the growth of tumors significantly, as compared to controls. Conclusion: In this study, a novel mimotope AAV-based platform was created allowing the isolation of mimotopes, which can be directly used as anticancer vaccines. The example of trastuzumab AAV-mimotopes demonstrates that this vaccine strategy could help to establish active immunotherapy for breast-cancer patients.