Efficacy and safety of Trastuzumab Emtansine in treating human epidermal growth factor receptor 2-positive metastatic breast cancer in Chinese population: a real-world multicenter study

Background

Trastuzumab emtansine (T-DM1) has been approved worldwide for treating metastatic breast cancer (mBC) in patients who have received first-line therapy, shown disease progression, and are human epidermal growth factor receptor 2 (HER2)-positive. T-DM1 received approval in China to treat early-stage breast cancer (BC) in 2020 and for mBC in 2021. In March 2023, T-DM1 was included in medical insurance coverage, significantly expanding the eligible population.

Materials and methods

This post-marketing observational study aimed to assess the safety and effectiveness of T-DM1 in real-world clinical practice in China. This study enrolled 31 individuals with HER2-positive early-stage BC and 70 individuals with HER2-positive advanced BC from 8 study centers in Shandong Province, China. The T-DM1 dosage was 3.6 mg/kg injected intravenously every 3 weeks until the disease advanced or the drug toxicity became uncontrollable, whichever occurred earlier. Additionally, efficacy and safety information on T-DM1 were collected.

Results

During the 7-month follow-up period, no recurrence or metastases were observed in patients who had early-stage BC. The disease control rate was 31.43% (22/70) in patients with advanced BC. The most common adverse effect of T-DM1 was thrombocytopenia, with an incidence of 69.31% (70/101), and the probability of Grade ≥ 3 thrombocytopenia was 11.88% (12/101).

Conclusion

This real-world study demonstrated that T-DM1 had good efficacy and was well tolerated by both HER2-positive early-stage BC and mBC patients.

Exploring the Combined Action of Adding Pertuzumab to Branded Trastuzumab versus Trastuzumab Biosimilars for Treating HER2+ Breast Cancer

The binding activity of various trastuzumab biosimilars versus the branded trastuzumab towards the glycosylated extracellular domain of the human epidermal growth factor receptor 2 (HER2) target in the presence of pertuzumab was investigated. We employed size exclusion chromatography with tetra-detection methodology to simultaneously determine absolute molecular weight, concentration, molecular size, and intrinsic viscosity. All trastuzumab molecules in solution exhibit analogous behavior in their binary action towards HER2 regardless of the order of addition of trastuzumab/pertuzumab. This analogous behavior of all trastuzumab molecules, including biosimilars, highlights the robustness and consistency of their binding activity towards HER2. Furthermore, the addition of HER2 to a mixture of trastuzumab and pertuzumab leads to increased formation of high-order HER2 complexes, up to concentrations of one order of magnitude higher than in the case of sequential addition. The observed increase suggests a potential synergistic effect between these antibodies, which could enhance their therapeutic efficacy in HER2-positive cancers. These findings underscore the importance of understanding the complex interplay between therapeutic antibodies and their target antigens, providing valuable insights for the development of more effective treatment strategies.

Incidence of antibody-drug conjugate-related fatigue in patients with breast cancer: A systematic review and meta-analysis

BACKGROUND

Numerous studies have reported the efficacy of antibody-drug conjugates (ADCs) for treating breast cancer. However, during cytotoxic drug treatment, long-term disabling fatigue is common. Moreover, studies in the relevant literature have indicated that fatigue can significantly increase the incidence of depression and sleep disorders. Therefore, this meta-analysis aims to evaluate the incidence of fatigue in breast cancer survivors treated with ADCs.

METHODS

PubMed, EMBASE, Web of Science, and Cochrane Library databases were systematically searched for articles and conference abstracts published before March 16, 2023. Further, two authors independently extracted data from the included studies. The primary outcome of this study was the incidence of all-grade fatigue caused by the use of ADCs in patients with breast cancer. Finally, a random-effects model was used to calculate the incidence and 95% confidence intervals (CIs) of the outcome.

RESULTS

Overall, 7963 patients from 31 studies were included in this meta-analysis to assess the incidence of fatigue caused by the use of approved and marketed ADCs in patients with breast cancer. Notably, the incidence of all-grade fatigue during ADC monotherapy was 39.84% (95% CI, 35.09%-44.69%). In subgroup analyses, among ADCs, the incidence of trastuzumab deruxtecan-induced fatigue was the highest, with an all-grade fatigue incidence of 47.05% (95% CI, 42.38%-51.75%). Meanwhile, the incidence of trastuzumab emtansine (T-DM1)-induced all-grade fatigue was 35.17% (95% CI, 28.87%-41.74%), which was the lowest among ADCs. Further, the incidence of all-grade fatigue due to sacituzumab govitecan was 42.82% (95% CI, 34.54%-51.32%), which was higher than that due to T-DM1. Moreover, the incidence of fatigue was higher with T-DM1 combination therapy than with monotherapy.

CONCLUSIONS

Clinicians have highlighted the high incidence of ADC-related fatigue and its negative impact on patients' physical and mental health, making fatigue an important research variable. The results of this study will further contribute to a comprehensive understanding of ADCs, which have some clinical importance and are of great benefit to patients with breast cancer.

The promise and challenges of combination therapies with antibody-drug conjugates in solid tumors

Antibody-drug conjugates (ADCs) represent an important class of cancer therapies that have revolutionized the treatment paradigm of solid tumors. To date, many ongoing studies of ADC combinations with a variety of anticancer drugs, encompassing chemotherapy, molecularly targeted agents, and immunotherapy, are being rigorously conducted in both preclinical studies and clinical trial settings. Nevertheless, combination therapy does not always guarantee a synergistic or additive effect and may entail overlapping toxicity risks. Therefore, understanding the current status and underlying mechanisms of ADC combination therapy is urgently required. This comprehensive review analyzes existing evidence concerning the additive or synergistic effect of ADCs with other classes of oncology medicines. Here, we discuss the biological mechanisms of different ADC combination therapy strategies, provide prominent examples, and assess their benefits and challenges. Finally, we discuss future opportunities for ADC combination therapy in clinical practice.

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.

Association of PIK3CA mutation with outcomes in HER2-positive breast cancer treated with anti-HER2 therapy: A meta-analysis and bioinformatic analysis of TCGA‑BRCA data

BACKGROUND

This study aimed to comprehensively explore the clinical significance of PIK3CA mutation in human epidermal growth factor receptor 2 (HER2)-positive breast cancer treated with anti-HER2 therapy.

METHODS

We systematically searched PubMed, Embase, and the Cochrane databases for eligible studies assessing the association between PIK3CA mutation and outcomes in patients with HER2-positive breast cancer receiving anti-HER2 therapy. The main outcomes included: (1) pathological complete response (pCR) or disease-free survival (DFS) for the neoadjuvant setting; (2) DFS or invasive DFS for the adjuvant setting; (3) objective response rate (ORR), progression-free survival (PFS), time-to-progression (TTP), or overall survival (OS) for the metastatic setting. The mutational landscape of HER2-positive breast cancer according to PIK3CA mutation status was examined based on TCGA breast cancer dataset.

RESULTS

Totally, 43 eligible studies, covering 11,099 patients with available data on PIK3CA mutation status, were identified. In the neoadjuvant setting, PIK3CA mutation was significantly associated with a lower pCR rate (OR=0.23, 95% CI 0.19-0.27, p<0.001). This association remained significant irrespective of the type of anti-HER2 therapy (single-agent or dual-agent) and hormone receptor status. There were no significant differences in DFS between PIK3CA mutated and wild-type patients in either the neoadjuvant or adjuvant settings. In the metastatic setting, PIK3CA mutation predicted worse ORR (OR=0.26, 95%CI 0.17-0.40, p<0.001), PFS (HR=1.28, 95%CI 1.03-1.59, p = 0.024) and TTP (HR=2.27, 95%CI 1.54-3.34, p<0.001). However, no significant association was observed between PIK3CA mutation status and OS. Distinct mutational landscapes were observed in HER2-positive breast cancer between individuals with PIK3CA mutations and those with wild-type PIK3CA.

CONCLUSIONS

PIK3CA mutation was significantly associated with a lower pCR rate in HER2-positive breast cancer treated with neoadjuvant anti-HER2 therapy. In the metastatic setting, PIK3CA mutation was predictive of worse ORR, PFS and TTP. These results suggest the potential for developing PI3K inhibitors as a therapeutic option for these patients.

Antibody-Drug Conjugate Targets, Drugs and Linkers

Antibody-drug conjugates offer the possibility of directing powerful cytotoxic agents to a malignant tumor while sparing normal tissue. The challenge is to select an antibody target expressed exclusively or at highly elevated levels on the surface of tumor cells and either not all or at low levels on normal cells. The current review explores 78 targets that have been explored as antibody-drug conjugate targets. Some of these targets have been abandoned, 9 or more are the targets of FDA-approved drugs, and most remain active clinical interest. Antibody-drug conjugates require potent cytotoxic drug payloads, several of these small molecules are discussed, as are the linkers between the protein component and small molecule components of the conjugates. Finally, conclusions regarding the elements for the successful antibody-drug conjugate are discussed.

Trastuzumab Emtansine Plus Pertuzumab Versus Taxane Plus Trastuzumab Plus Pertuzumab After Anthracycline for High-Risk Human Epidermal Growth Factor Receptor 2-Positive Early Breast Cancer: The Phase III KAITLIN Study

PURPOSE

We aimed to improve efficacy and reduce toxicity of high-risk human epidermal growth factor receptor 2 (HER2)-positive early breast cancer (EBC) treatment by replacing taxanes and trastuzumab with trastuzumab emtansine (T-DM1).

METHODS

The phase III KAITLIN study (NCT01966471) included adults with excised HER2-positive EBC (node-positive or node-negative, hormone receptor-negative, and tumor > 2.0 cm). Postsurgery, patients were randomly assigned 1:1 to anthracycline-based chemotherapy (three-four cycles) and then 18 cycles of T-DM1 plus pertuzumab (AC-KP) or taxane (three-four cycles) plus trastuzumab plus pertuzumab (AC-THP). Adjuvant radiotherapy/endocrine therapy was permitted. Coprimary end points were invasive disease-free survival (IDFS) in the intention-to-treat node-positive and overall populations with hierarchical testing.

RESULTS

The median follow-up was 57.1 months (interquartile range, 52.1-60.1 months) for AC-THP (n = 918) and 57.0 months (interquartile range, 52.1-59.8 months) for AC-KP (n = 928). There was no significant IDFS difference between arms in the node-positive (n = 1,658; stratified hazard ratio [HR], 0.97; 95% CI, 0.71 to 1.32) or overall population (n = 1846; stratified HR, 0.98; 95% CI, 0.72 to 1.32). In the overall population, the three-year IDFS was 94.2% (95% CI, 92.7 to 95.8) for AC-THP and 93.1% (95% CI, 91.4 to 94.7) for AC-KP. Treatment completion rates (ie, 18 cycles) were 88.4% for AC-THP and 65.0% for AC-KP (difference driven by T-DM1 discontinuation because of laboratory abnormalities [12.5%]). Similar rates of grade ≥ 3 (55.4% v 51.8%) and serious adverse events (23.3% v 21.4%) occurred with AC-THP and AC-KP, respectively. KP decreased clinically meaningful deterioration in global health status versus THP (stratified HR, 0.71; 95% CI, 0.62 to 0.80).

CONCLUSION

The primary end point was not met. Both arms achieved favorable IDFS. Trastuzumab plus pertuzumab plus chemotherapy remains the standard of care for high-risk HER2-positive EBC.

Antibody-drug conjugates in treating older patients suffering from cancer: what is the real value?

Immunotherapeutic drugs and target therapies have represented an epochal change in treating cancer patients. They represent an attractive option in oncologists' armamentarium, particularly if we consider the optimal balance between efficacy and toxicity. As a step forward, immuno- and target-therapies have merged intending to improve efficacy: antibody-drug conjugates ensure the perfect combination. They allow the delivery of large amounts of drugs to the target with a limited 'off-target' effect and a low rate of adverse events. These aspects could make immunoconjugates palatable as the first choice for fragile patients, but solid evidence does not exist on the use of these drugs in this population type, especially older people.

A Companion Diagnostic With Significant Clinical Impact in Treatment of Breast and Gastric Cancer

The development of trastuzumab (Herceptin^®) was one of the most significant cancer drug development projects of the 20th century. Not only was it a scientific and medical achievement but it also paved the way for the drug-diagnostic codevelopment model, where a predictive biomarker assay is developed in parallel to the drug. One of the challenges in the development of trastuzumab was to select the right patient population likely to respond and here, it was critical to have access to an accurate, robust and reliable assay for detection of HER2 overexpression in tumors. In the clinical development of trastuzumab, a clinical trial assay (CTA), developed by Genentech, was used for selection of HER2 positive patients. However, during the phase III trial with trastuzumab, a new optimized IHC assay, HercepTest™ was designed and developed by Dako. In the final stage of its development, a comparative study with the CTA was conducted in order to show concordance between the two assays. In September 1998, the Food and Drug Administration (FDA) simultaneously granted approval to trastuzumab and HercepTest™. The assay has been used for patient selection in a number of significant breast cancer clinical trials such as the HERA, CLEOPATRA, EMILIA and more. In these trials, HercepTest™ demonstrated its clinical utility in the neoadjuvant, adjuvant, and metastatic setting as well as in relation to different types of HER2 targeted therapies. Likewise, the assay was used for selection of HER2 positive gastric cancer patients in the important ToGA trail. HercepTest™ was the first companion diagnostic ever approved by the FDA, and more than 20 years of use has documented its clinical impact.

Pertuzumab and trastuzumab emtansine in patients with HER2-amplified metastatic colorectal cancer: the phase II HERACLES-B trial

BACKGROUND

HER2 is a therapeutic target for metastatic colorectal cancer (mCRC), as demonstrated in the pivotal HERACLES-A (HER2 Amplification for Colo-rectaL cancer Enhanced Stratification) trial with trastuzumab and lapatinib. The aim of HERACLES-B trial is to assess the efficacy of the combination of pertuzumab and trastuzumab-emtansine (T-DM1) in this setting.

METHODS

HERACLES-B was a single-arm, phase II trial, in patients with histologically confirmed RAS/BRAF wild-type and HER2+ mCRC refractory to standard treatments. HER2 positivity was assessed by immunohistochemistry and in situ hybridisation according to HERACLES criteria. Patients were treated with pertuzumab (840 mg intravenous load followed by 420 mg intravenous every 3 weeks) and T-DM1 (3.6 mg/kg every 3 weeks) until disease progression or toxicity. Primary and secondary end points were objective response rate (ORR) and progression-free survival (PFS). With a Fleming/Hern design (H0=ORR 10%; α=0.05; power=0.85), 7/30 responses were required to demonstrate an ORR ≥30% (H1).

RESULTS

Thirty-one patients, 48% with ≥4 lines of previous therapies, were treated and evaluable. ORR was 9.7% (95% CI: 0 to 28) and stable disease (SD) 67.7% (95% CI: 50 to 85). OR/SD ≥4 months was associated with higher HER2 immunohistochemistry score (3+ vs 2+) (p = 0.03). Median PFS was 4.1 months (95% CI: 3.6 to 5.9). Drug-related grade (G) 3 adverse events were observed in two patients (thrombocytopaenia); G≤2 AE in 84% of cycles (n = 296), mainly nausea and fatigue.

CONCLUSIONS

HERACLES-B trial did not reach its primary end point of ORR; however, based on high disease control, PFS similar to other anti-HER2 regimens, and low toxicity, pertuzumab in combination with T-DM1 can be considered for HER2+mCRC as a potential therapeutic resource.

TRIAL REGISTRATION NUMBER

2012-002128-33 and NCT03225937.

Hsp90 inhibition and co-incubation with pertuzumab induce internalization and degradation of trastuzumab: Implications for use of T-DM1

The receptor tyrosine kinase HER2 is associated with a number of human malignancies and is an important therapeutic target. The antibody-drug conjugate trastuzumab emtansine (T-DM1; Kadcyla^® ) is recommended as a first-line treatment for patients with HER2-positive metastatic breast cancer. T-DM1 combines the antibody-induced effects of the anti-HER2 antibody trastuzumab (Herceptin^® ) with the cytotoxic effect of the tubulin inhibitor mertansine (DM1). For DM1 to have effect, the T-DM1-HER2 complex has to be internalized and the trastuzumab part of T-DM1 has to be degraded. HER2 is, however, considered endocytosis-resistant. As a result of this, trastuzumab is only internalized to a highly limited extent, and if internalized, it is rapidly recycled. The exact reasons for the endocytosis resistance of HER2 are not clear, but it is stabilized by heat-shock protein 90 (Hsp90) and Hsp90 inhibitors induce internalization and degradation of HER2. HER2 can also be internalized upon activation of protein kinase C, and contrary to trastuzumab alone, the combination of two or more anti-HER2 antibodies can induce efficient internalization and degradation of HER2. With intention to find ways to improve the action of T-DM1, we investigated how different ways of inducing HER2 internalization leads to degradation of trastuzumab. The results show that although both Hsp90 inhibition and activation of protein kinase C induce internalization of trastuzumab, only Hsp90 inhibition induces degradation. Furthermore, we find that antibody internalization and degradation are increased when trastuzumab is combined with the clinically approved anti-HER2 antibody pertuzumab (Perjeta^® ).

Improving Receptor-Mediated Intracellular Access and Accumulation of Antibody Therapeutics-The Tale of HER2

Therapeutic anti-HER2 antibodies and antibody-drug conjugates (ADCs) have undoubtedly benefitted patients. Nonetheless, patients ultimately relapse-some sooner than others. Currently approved anti-HER2 drugs are expensive and their cost-effectiveness is debated. There is increased awareness that internalization and lysosomal processing including subsequent payload intracellular accumulation and retention for ADCs are critical therapeutic attributes. Although HER2 preferential overexpression on the surface of tumor cells is attractive, its poor internalization and trafficking to lysosomes has been linked to poor therapeutic outcomes. To help address such issues, this review will comprehensively detail the most relevant findings on internalization and cellular accumulation for approved and investigational anti-HER2 antibodies and ADCs. The improved clarity of the HER2 system could improve antibody and ADC designs and approaches for next-generation anti-HER2 and other receptor targeting agents.

Tubulin Maytansine Site Binding Ligands and their Applications as MTAs and ADCs for Cancer Therapy

BACKGROUND

Microtubule Targeting Agents (MTAs) represent the most successful anticancer drugs for cancer chemotherapy. Through interfering with the tubulin polymerization and depolymerization dynamics, MTAs influence intracellular transport and cell signal pathways, inhibit cell mitosis and cell proliferation, and induce cell apoptosis and death. The tubulin maytansine site binding agents are natural or nature-derived products that represent one type of the MTAs that inhibit tubulin polymerization and exhibit potent antitumor activity both in vitro and in vivo. They are used as Antibody-Drug Conjugates (ADCs) in cancer chemotherapy.

METHODS

Using SciFinder® as a tool, the publications about maytansine, its derivatives, maytansine binding site, maytansine site binding agents and their applications as MTAs for cancer therapy were surveyed with an exclusion on those published as patents. The latest progresses in clinical trials were obtained from the clinical trial web.

RESULTS

This article presents an introduction about MTAs, maytansine, maytansine binding site and its ligands, the applications of these ligands as MTAs and ADCs in cancer therapy.

CONCLUSION

The maytansine site binding agents are powerful MTAs for cancer chemotherapy. The maytansine site ligands-based ADCs are used in clinic or under clinical trials as cancer targeted therapy to improve their selectivity and to reduce their side effects. Further improvements in the delivery efficiency of the ADCs will benefit the patients in cancer targeted therapy.

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 for Cancer Treatment

The concept of exploiting the specific binding properties of monoclonal antibodies as a mechanism for selective delivery of cytotoxic agents to tumor cells is an attractive solution to the challenge of increasing the therapeutic index of cell-killing agents for treating cancer. All three parts of an antibody-drug conjugate (ADC)-the antibody, the cytotoxic payload, and the linker chemistry that joins them together-as well as the biologic properties of the cell-surface target antigen are important in designing an effective anticancer agent. The approval of brentuximab vedotin in 2011 for treating relapsed Hodgkin's lymphoma and systemic anaplastic large cell lymphoma, and the approval of ado-trastuzumab emtansine in 2013 for treating HER2-positive metastatic breast cancer, have sparked vigorous research in the field, with >65 ADCs currently in clinical evaluation. This review highlights the ADCs that are approved for marketing, in pivotal clinical trials, or in at least phase II clinical development for treating both hematologic malignancies and solid tumors.

Biomarker analysis of the GATSBY study of trastuzumab emtansine versus a taxane in previously treated HER2-positive advanced gastric/gastroesophageal junction cancer

BACKGROUND

Prespecified exploratory biomarker analyses of the phase II/III GATSBY study (NCT01641939) assessed whether patient subgroups experienced a survival benefit from trastuzumab emtansine (T-DM1) versus taxane therapy, and to advance understanding of HER2-positive advanced gastric/gastroesophageal junction cancer (AGC) disease biology.

METHODS

Adults with HER2-positive AGC whose disease progressed during/after first-line therapy were enrolled and randomized to receive T-DM1 [Stage 1: 3.6 mg/kg q3w, 2.4 mg/kg qw, or taxane (docetaxel/paclitaxel); Stage 2: 2.4 mg/kg qw or taxane]. Primary efficacy endpoint was overall survival (OS). Prespecified exploratory biomarkers included HER2, HER3, PTEN, PIK3CA mutation status, FcγR, and cMET. Tumor samples from patients who received 2.4 mg/kg T-DM1 (n = 228) or taxane (n = 117) were included.

RESULTS

Median OS was longer in subgroups with HER2 immunohistochemistry (IHC) 3+ [9.5 versus 8.3 months for T-DM1 versus taxane; hazard ratio (HR) 0.99 (95% CI 0.68-1.43)] versus HER2 IHC 2+/in situ hybridization-positive [5.2 versus 9.2 months for T-DM1 versus taxane; HR 1.53 (95% CI 0.94-2.50)] tumors. Trends towards increased median OS were also observed in subgroups with > versus ≤ median HER2 mRNA expression, higher versus lower HER2 gene copy number, HER2 gene ratio and H score, and homogenous or nonfocal HER2 IHC staining. T-DM1 was not associated with superior OS versus taxane in any subgroup.

CONCLUSIONS

Patients with previously treated HER2-positive AGC with higher HER2 expression experienced a better treatment effect from T-DM1 than those with lower HER2 expression and may derive comparable survival benefits from T-DM1 and taxane therapy.

CLINICAL TRIALS REGISTRATION

NCT01641939 ( https://clinicaltrials.gov/ct2/show/NCT01641939 ).

The Use of Immunotherapy to Treat Metastatic Breast Cancer

This article reviews the principal attempts of immune-modulation or immune therapy in metastatic breast cancer. It considers their rationale and reports on results from the relevant key clinical trials. Immune-modulatory or immune-stimulating cytokines used alone or combined with conventional therapies is among the principal approaches of immune manipulation in breast cancer. As this issue has recently been reviewed by us, the aim of the current article is to discuss our updated and unpublished data on this topic. Overall survival in luminal (28 patients) and non-luminal (9 patients) molecular subtypes is 91 and 59 months respectively that is about two and half or three times longer than expected. Thereafter, we focus on monoclonal antibodies (mAb) based-therapies including novel strategies to overcome resistance to anti-HER2 mAb. The main vaccine platforms in different molecular subtypes and immune therapies in triple negative metastatic breast cancer (m-TNBC) are discussed in the last sections. Some phase III investigations have already changed the current clinical practice. In fact, pertuzumab plus trastuzumab and docetaxel is the recommended first line regimen in HER2 positive locally recurrent or metastatic breast cancer and bevacizumab plus paclitaxel or docetaxel is a reasonable option for m-TNBC. In some other observational or phase I/II studies on first-line trastuzumab plus chemotherapy and hormonal therapy and in that on HER2 peptide/protein vaccines promising although preliminary findings have been reported to be further validated. In the remaining studies, results were disappointing. In the future, finding new predictive biomarkers and exploring more suitable synergizing combinations, time and dose-dependent-scheduled sequences of currently and further investigated immunological approaches are main challenges.

Relationship between tumor biomarkers and efficacy in MARIANNE, a phase III study of trastuzumab emtansine ± pertuzumab versus trastuzumab plus taxane in HER2-positive advanced breast cancer

Background

The phase III EMILIA and TH3RESA trials demonstrated clinical benefits of trastuzumab emtansine (T-DM1) therapy in patients with previously treated HER2-positive metastatic breast cancer (MBC). Data from these and other trials showed that T-DM1–associated survival benefits were observed across biomarker subgroups tested in these trials. Prespecified, exploratory analyses of the phase III MARIANNE study examined the effects of HER2-related biomarkers on PFS in patients administered T-DM1 in the first-line MBC setting.

Methods

In MARIANNE, patients with previously untreated HER2-positive MBC were randomized (1:1:1) to trastuzumab plus taxane, T-DM1 plus placebo, or T-DM1 plus pertuzumab. Biomarker subgroups included HER2 and HER3 mRNA expression levels (≤median vs. >median), HER2 staining intensity (IHC 3+ vs. 2+ vs. 0/1+), PIK3CA status (mutated vs. non-mutated), PTEN H-score (≤median vs. >median), and PTEN protein expression level (0 vs. 1+ vs. 2+ vs. 3+ vs. 4+). PFS was analyzed descriptively for each subgroup using Kaplan–Meier methodology. Additional exploratory post-hoc analyses evaluated the effects of HER2 heterogeneity. Multivariate analyses were also performed.

Results

Median PFS was numerically longer for patients with HER2 mRNA levels >median versus ≤median across treatment arms. In general, there were no predictive biomarkers of benefit for either T-DM1 treatment arm; most hazard ratios were close to 1 with wide confidence intervals that included the value 1. Focal HER2 expression (IHC 3+ or IHC 2+) was present in 3.8% of patients and was associated with numerically shorter PFS in the T-DM1–containing treatment arms versus trastuzumab plus taxane. Compared with non-mutated PIK3CA, mutated PIK3CA was associated with numerically shorter median PFS across treatment groups. Post-hoc multivariate analysis showed HER2 mRNA expression and mutated PIK3CA were prognostic for PFS (P ≤ 0.001 for both biomarkers).

Conclusions

In MARIANNE, biomarkers related to the HER2 pathway did not have predictive value for PFS when comparing T-DM1 (with or without pertuzumab) with trastuzumab plus taxane. However, HER2 mRNA level and PIK3CA mutation status showed prognostic value. Evaluation of other potential biomarkers, including immune markers, is ongoing.

Trial registration

Registration number: NCT01120184. Date of registration: April 28, 2010 (registered prospectively).

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5687-0) contains supplementary material, which is available to authorized users.

Pertuzumab for the treatment of breast cancer

Introduction: Pertuzumab, a humanized monoclonal antibody that binds the human epidermal growth factor receptor 2 (HER2), inhibits the heterodimerization of HER2 with other HER receptors. It has been approved both by the Food and Drug Administration and the European Medicine Agency in the metastatic, neoadjuvant and adjuvant setting.Areas covered: This review analyses and discusses preclinical and clinical studies of pertuzumab in breast cancer. In this article, we review the status of pertuzumab, the completed and ongoing trials, and its safety.Expert opinion: Pertuzumab is a key drug for the treatment of HER2-positive metastatic or early breast cancer. However, it is imperative to identify patients that will need dual-targeting and mechanisms of resistance. Moreover, the value of pertuzumab beyond progression needs to be evaluated.

Monoclonal antibodies for the treatment of non-hematological tumors: a safety review

Introduction: The introduction of monoclonal antibodies (moAbs) into clinical practice revolutionized the treatment strategies in several solid tumors. These agents differ from cytotoxic chemotherapy for their mechanism of action and toxicity. By targeting specific antigens present on healthy cells and modulating immune system activity, these biological drugs are able to generate a wide spectrum of peculiar adverse events that can negatively impact on patients' quality of life. Areas covered: In this review, the main side effects associated with the use of moAbs have been described to show their incidence and current management strategies, which may drive clinicians in their daily practice. Expert opinion: The majority of these drugs represents an example of successful innovation, since they are able to induce a significant improvement of patients' survival and quality of life without any increase in related side effects as compared to standard cancer treatments. For this reason, they have become new milestones in personalized therapy for different non-hematological malignancies. With the increasing use of moAbs in treatment regimens, it is strongly recommended that clinicians are knowledgeable about the side effects associated with these agents, their management and monitoring, to optimize the clinical treatment of cancer patients.

Pertuzumab, trastuzumab and taxane-based treatment for visceral organ metastatic, trastuzumab-naïve breast cancer: real-life practice outcomes

PURPOSE

In this study, we aimed to describe the real-life practice outcomes of pertuzumab-trastuzumab-taxane (PTT) combination in visceral organ metastatic, trastuzumab-naive breast cancer (BC) patients.

METHODS

This study was conducted by Turkish Oncology Group and included 317 patients' data from 36 centers.

RESULTS

Median age was 51 (22-82). Median PFS was 28.5 months, while median OS was 40.3 months. Patients with brain metastases (n: 13, 4.1%) had worse PFS (16.8 m vs. 28.5 m; p = 0.002) and OS (26.7 m vs. 40.3 m; p = 0.009). Patients older than 65 years of age (n: 42, 13.2%) had significantly lower OS results (19.8 m vs. 40.3 m; p = 0.01). Two hundred sixty-eight patients (86.7%) received docetaxel while 37 patients (11.7%) received paclitaxel. PFS and OS were similar between taxane groups. In eight patients (2.5%), 5-40% ejection fraction decrement from baseline was detected without any clinical sign of heart failure.

CONCLUSIONS

Our RLP trial included only visceral metastatic, trastuzumab-naïve BC patients including cases with brain involvement who received PTT combination in the first-line treatment. Regardless of negative prognostic characteristics, our results are in parallel with pivotal trial. Further strategies for brain metastasis should be developed to improve outcomes despite encouraging results with PTT treatment. Taxane selection can be personalized and endocrine maintenance may further improve outcomes after taxanes were discontinued. To our knowledge, this is the largest scale real-life clinical practice study of pertuzumab-trastuzumab-taxane therapy to date.

Metastatic and triple-negative breast cancer: challenges and treatment options

The major current conventional types of metastatic breast cancer (MBC) treatments include surgery, radiation, hormonal therapy, chemotherapy, or immunotherapy. Introducing biological drugs, targeted treatment and gene therapy can potentially reduce the mortality and improve the quality of life in patients with MBC. However, combination of several types of treatment is usually recommended. Triple negative breast cancer (TNBC) accounts for 10-20% of all cases of breast carcinoma and is characterized by the low expression of progesterone receptor (PR), estrogen receptor (ER), and human epidermal growth factor receptor 2 (HER2). Consequently, convenient treatments used for MBC that target these receptors are not effective for TNBC which therefore requires special treatment approaches. This review discusses the occurrence of MBC, the prognosis and predictive biomarkers of MBC, and focuses on the novel advanced tactics for treatment of MBC and TNBC. Nanotechnology-based combinatorial approach for the suppression of EGFR by siRNA and gifitinib is described.

Targeted agents for HER2-positive breast cancer in older adults: current and future perspectives

INTRODUCTION

One-third of breast cancer (BC) cases worldwide occur in women aged 65 years and older, with 10 to 15% overexpressing the human epidermal growth factor receptor 2 (HER2). Although several HER2-targeted therapies have been developed, the lack of data regarding their use in older patients hampers evidence-based decision-making for this population.

AREAS COVERED

We review current evidence on the efficacy and safety of HER2-targeted therapies in older adults with BC, focusing on approved therapies such as trastuzumab, lapatinib, pertuzumab, ado-trastuzumab-emtansine, and neratinib. Additionally, we discuss drugs under development to target the HER2-receptor, and to overcome resistance to existing therapies. Finally, we highlight the cardiotoxicity of HER2-targeted drugs among older adults.

EXPERT OPINION

Older adults are underrepresented in trials of HER2-targeted therapies in BC. We propose strategies to increase recruitment of older adults in clinical trials in order to increase the evidence base to treat this growing population.

Combination therapies for the treatment of HER2-positive breast cancer: current and future prospects

INTRODUCTION

HER2-positive disease is an aggressive subtype of breast cancer that has been revolutionized by anti-HER2 directed therapies. Multiple drugs have been developed and are currently in clinical use, including trastuzumab, lapatinib, pertuzumab, T-DM1, and neratinib, alone or combined in 'dual HER2-blockade' regimens. Areas covered: A comprehensive literature review was performed regarding the current state and the future of combination regimens containing anti-HER2 agents, focusing on their efficacy, toxicity, and cost-effectiveness. Expert commentary: The combination of trastuzumab/pertuzumab is approved in all disease settings, while trastuzumab/neratinib is approved in the adjuvant setting and trastuzumab/lapatinib in metastatic disease. Meanwhile, as breast cancer biology and resistance mechanisms become clearer, combinations with drugs like PI3K/Akt/mTOR inhibitors, CDK4/6 inhibitors, anti-PD(L)1 antibodies, endocrine therapy, and new anti-HER2 agents (panHER and HER2 tyrosine kinase inhibitors, bispecific antibodies, anti-HER3 antibodies, and antibody-drug conjugates) are being extensively tested in clinical trials. More specific strategies for the 'triple-positive' (estrogen receptor-positive/HER2-positive) disease are also being explored. However, there is an urgent need for the development of predictive biomarkers for a better tailoring of anti-HER2 directed therapy. This is the only way to further improve clinical outcomes and quality of life and to decrease costs and toxicities of unnecessary treatments.

Trastuzumab emtansine: determining its role in management of HER2+ breast cancer

Trastuzumab emtansine is an antibody-drug conjugate comprised of the anti-HER2 monoclonal antibody trastuzumab linked to DM1 (emtansine), a potent cytotoxic maytansinoid derivative, by a stable linker. This structure results in improved tumor-directed cytotoxicity in HER2+ breast cancer with reduced systemic toxicities, particularly the cardiac toxicities associated with single agent trastuzumab. Phase III trials have demonstrated improved progression-free and overall survival in heavily pretreated patients with advanced HER2+ breast cancer, with an acceptable toxicity profile. However, its role in first-line treatment is less clear. Ongoing studies continue to evaluate its role in neoadjuvant and adjuvant management of HER2+ breast cancer.

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.

Efficacy and safety of trastuzumab emtansine (T-DM1) in the treatment of HER2-positive metastatic breast cancer (MBC): a meta-analysis of randomized controlled trial

Aims

Trastuzumab emtansine (T-DM1), an antibody-drug conjugate against human epidermal growth factor receptor 2 (HER2), has been used in the treatment of patients with HER2-positive metastatic breast cancer (MBC). We conducted a meta-analysis to evaluate the efficacy and toxicity of T-DM1 for the treatment of patients with HER2-positive MBC.

Materials and Methods

Randomized controlled trials (RCTs), published in Pubmed, Embase, and Web of Science were systematically reviewed to assess the survival benefits and toxicity profile of HER2-positive patients with MBC who were treated with T-DM1. Outcomes included progression-free survival (PFS), overall survival (OS), overall response rate (ORR), and toxicities. Results were expressed as the hazard ratio (HR) with 95% confidence intervals (CIs).

Results

A total of 5 RCTs involving 3,720 patients met the inclusion criteria and were included in this meta-analysis. T-DM1 significantly prolonged PFS (HR = 0.73, 95% CI: 0.61, 0.86; P < 0.05), OS (HR = 0.68, 95% CI: 0.62, 0.74; P < 0.05), but it did not increase ORR (RR = 1.25, 95% CI: 0.94, 1.66; P = 0.148). Subgroup analysis indicated that T-DM1 significantly improved PFS when it was used as first-line (HR = 0.86, 95% CI: 0.74, 1.00; P < 0.05) or non-first-line treatment (HR = 0.65, 95% CI: 0.53, 0.81; P < 0.05). T-DM1 was associated with more frequent adverse events, including fatigue, elevated ALT, elevated AST, and thrombocytopenia, than other anti-HER2 therapies.

Conclusions

Based on the current evidence, T-DM1 significantly prolonged PFS and OS with a tolerated toxicity than other anti-HER2 therapies in patients with HER2-positive MBC. These findings confirm the use of T-DM1 for the treatment of patients with HER2-positive MBC. Further well-designed, multi-center RCTs needed to identify these findings.

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.

HER2-positive breast cancer

Anti-HER2 treatment for HER2-positive breast cancer has changed the natural biology of this disease. This Series article reviews the main achievements so far in the treatment of both metastatic and early HER2-positive breast cancer. The success of neoadjuvant therapy in HER2-positive early breast cancer is especially acknowledged, as pertuzumab has been approved on the basis of a higher proportion of patients achieving a pathological complete response with pertuzumab and trastuzumab than with trastuzumab alone in a neoadjuvant study. Event-free survival after the confirmatory adjuvant trial completed recruitment was numerically better with pertuzumab plus trastuzumab than with trastuzumab alone. With survival rates of almost 5 years in women with metastatic HER2-positive breast cancer and 75% of patients achieving a pathological complete response, new treatments in the past decade have clearly improved the prognosis of HER2-positive breast cancer. Despite these achievements, however, the persisting high toll of deaths resulting from HER2-positive breast cancer calls for continued, intensive clinical research of newer therapies and combinations.

Antibody-Drug Conjugates (ADCs) for Personalized Treatment of Solid Tumors: A Review

Attaching a cytotoxic "payload" to an antibody to form an antibody-drug conjugate (ADC) provides a mechanism for selective delivery of the cytotoxic agent to cancer cells via the specific binding of the antibody to cancer-selective cell surface molecules. The first ADC to receive marketing authorization was gemtuzumab ozogamicin, which comprises an anti-CD33 antibody conjugated to a highly potent DNA-targeting antibiotic, calicheamicin, approved in 2000 for treating acute myeloid leukemia. It was withdrawn from the US market in 2010 following an unsuccessful confirmatory trial. The development of two classes of highly potent microtubule-disrupting agents, maytansinoids and auristatins, as payloads for ADCs resulted in approval of brentuximab vedotin in 2011 for treating Hodgkin lymphoma and anaplastic large cell lymphoma, and approval of ado-trastuzumab emtansine in 2013 for treating HER2-positive breast cancer. Their success stimulated much research into the ADC approach, with >60 ADCs currently in clinical evaluation, mostly targeting solid tumors. Five ADCs have advanced into pivotal clinical trials for treating various solid tumors-platinum-resistant ovarian cancer, mesothelioma, triple-negative breast cancer, glioblastoma, and small cell lung cancer. The level of target expression is a key parameter in predicting the likelihood of patient benefit for all these ADCs, as well as for the approved compound, ado-trastuzumab emtansine. The development of a patient selection strategy linked to target expression on the tumor is thus critically important for identifying the population appropriate for receiving treatment.

Safety and efficacy evaluation of pertuzumab in patients with solid tumors

BACKGROUND

The development of targeted therapies benefits patients with certain markers in the treatment of breast cancer. Pertuzumab is a novel humanized monoclonal antibody that blocks human epidermal growth factor receptor 2 (HER2) dimerization. The Food and Drug Administration has approved pertuzumab in combination with trastuzumab and docetaxel for the treatment of patients with HER2-positive metastatic breast cancer.

METHODS

To assess the safety and efficacy profile of pertuzumab, we searched PubMed and Embase (articles from January 1966 to January 2015) using the keyword "pertuzumab".

RESULTS

Fourteen eligible studies were included in our final analysis. From the results of our analysis, diarrhea (56.9%, 95% confidence interval [CI] 49.6%-63.9%), nausea (34.0%, 95% CI 27.7%-40.8%), and rash (25.6%, 95% CI 20.8%-31.0%) were the most common adverse effects in pertuzumab alone and pertuzumab-based therapies. Based on randomized controlled clinical trials, diarrhea (odds ratio [OR] 2.310, 95% CI 1.818-2.936), rash (OR 1.848, 95% CI 1.094-3.122), and febrile neutropenia (OR 1.672, 95% CI 1.130-2.474) were of statistical significance, which meant that pertuzumab played a prominent role in the incidence of diarrhea. Meanwhile, pertuzumab showed its effective role in cancer control and lifetime prolongation.

CONCLUSION

In conclusion, considering that the common adverse effects for pertuzumab are gastrointestinal and skin toxicities, which are easier to handle than other toxicities, pertuzumab is a safe and effective drug for patients with solid tumors.

Trastuzumab Emtansine With or Without Pertuzumab Versus Trastuzumab Plus Taxane for Human Epidermal Growth Factor Receptor 2-Positive, Advanced Breast Cancer: Primary Results From the Phase III MARIANNE Study

Purpose Trastuzumab and pertuzumab are human epidermal growth factor receptor 2 (HER2) -targeted monoclonal antibodies, and trastuzumab emtansine (T-DM1) is an antibody-drug conjugate that combines the properties of trastuzumab with the cytotoxic activity of DM1. T-DM1 demonstrated encouraging efficacy and safety in a phase II study of patients with previously untreated HER2-positive metastatic breast cancer. Combination T-DM1 and pertuzumab showed synergistic activity in cell culture models and had an acceptable safety profile in a phase Ib and II study. Methods In the MARIANNE study, 1,095 patients with centrally assessed, HER2-positive, advanced breast cancer and no prior therapy for advanced disease were randomly assigned 1:1:1 to control (trastuzumab plus taxane), T-DM1 plus placebo, hereafter T-DM1, or T-DM1 plus pertuzumab at standard doses. Primary end point was progression-free survival (PFS), as assessed by independent review. Results T-DM1 and T-DM1 plus pertuzumab showed noninferior PFS compared with trastuzumab plus taxane (median PFS: 13.7 months with trastuzumab plus taxane, 14.1 months with T-DM1, and 15.2 months with T-DM1 plus pertuzumab). Neither experimental arm showed PFS superiority to trastuzumab plus taxane. Response rate was 67.9% in patients who were treated with trastuzumab plus taxane, 59.7% with T-DM1, and 64.2% with T-DM1 plus pertuzumab; median response duration was 12.5 months, 20.7 months, and 21.2 months, respectively. The incidence of grade ≥ 3 adverse events was numerically higher in the control arm (54.1%) versus the T-DM1 arm (45.4%) and T-DM1 plus pertuzumab arm (46.2%). Numerically fewer patients discontinued treatment because of adverse events in the T-DM1 arms, and health-related quality of life was maintained for longer in the T-DM1 arms. Conclusion T-DM1 showed noninferior, but not superior, efficacy and better tolerability than did taxane plus trastuzumab for first-line treatment of HER2-positive, advanced breast cancer.

Relationship between tumor biomarkers and efficacy in TH3RESA, a phase III study of trastuzumab emtansine (T‐DM1) vs. treatment of physician's choice in previously treated HER2‐positive advanced breast cancer

In the phase III TH3RESA study (NCT01419197), 602 patients with HER2‐positive advanced breast cancer who received prior taxane therapy and ≥2 HER2‐directed regimens, including trastuzumab and lapatinib (advanced setting), were randomized to trastuzumab emtansine (T‐DM1) or treatment of physician's choice (TPC). A statistically significant progression‐free survival (PFS) benefit favoring T‐DM1 was demonstrated. Here, we examine the relationship between HER2‐related biomarkers and PFS in an exploratory analysis. Biomarkers assessed included HER2 (n = 505) and HER3 (n = 505) mRNA expression, PIK3CA mutation status (n = 410) and PTEN protein expression (n = 358). For biomarkers with continuous data (HER2, HER3, PTEN), subgroups were defined using median values (>median and ≤median). For all biomarker subgroups, median PFS was longer with T‐DM1 vs. TPC. The PFS benefit favoring T‐DM1 vs. TPC was numerically greater in the HER2 mRNA >median subgroup (7.2 vs. 3.4 months; unstratified hazard ratio [HR], 0.40; 95% CI, 0.28–0.59; p < 0.0001) vs. ≤median subgroup (5.5 vs. 3.9 months; HR, 0.68; 95% CI, 0.49–0.92; p = 0.0131). The PFS benefit with T‐DM1 was similar among HER3, PIK3CA and PTEN subgroups. Consistent with other reports, benefit was seen with T‐DM1 regardless of PIK3CA mutation status. In a multivariate analysis including an interaction term (treatment group by log2‐transformed HER2 mRNA), patients with higher HER2 mRNA levels benefited more from receiving T‐DM1 (HR, 0.84; 95% CI, 0.75–0.94; interaction p value = 0.0027). In summary, T‐DM1 prolonged median PFS in all biomarker subgroups analyzed, including activating PIK3CA mutations, with numerically greater benefit in patients with tumors expressing HER2 mRNA >median vs. ≤median.

Recent Advances in the Development of Antineoplastic Agents Derived from Natural Products

Through years of evolutionary selection pressures, organisms have developed potent toxins that coincidentally have marked antineoplastic activity. These natural products have been vital for the development of multiagent treatment regimens currently employed in cancer chemotherapy, and are used in the treatment of a variety of malignancies. Therefore, this review catalogs recent advances in natural product-based drug discovery via the examination of mechanisms of action and available clinical data to highlight the utility of these novel compounds in the burgeoning age of precision medicine. The review also highlights the recent development of antibody-drug conjugates and other immunotoxins, which are capable of delivering highly cytotoxic agents previously deemed too toxic to elicit therapeutic benefit preferentially to neoplastic cells. Finally, the review examines natural products not currently used in the clinic that have novel mechanisms of action, and may serve to supplement current chemotherapeutic protocols.

Relationship between Tumor Biomarkers and Efficacy in EMILIA, a Phase III Study of Trastuzumab Emtansine in HER2-Positive Metastatic Breast Cancer

PURPOSE

HER2-positive breast cancer is heterogeneous. Some tumors express mutations, like activating PIK3CA mutations or reduced PTEN expression, that negatively correlate with response to HER2-targeted therapies. In this exploratory analysis, we investigated whether the efficacy of trastuzumab emtansine (T-DM1), an antibody-drug conjugate comprised of the cytotoxic agent DM1 linked to the HER2-targeted antibody trastuzumab, was correlated with the expression of specific biomarkers in the phase III EMILIA study.

EXPERIMENTAL DESIGN

Tumors were evaluated for HER2 (n = 866), EGFR (n = 832), and HER3 (n = 860) mRNA expression by quantitative reverse transcriptase PCR; for PTEN protein expression (n = 271) by IHC; and for PIK3CA mutations (n = 259) using a mutation detection kit. Survival outcomes were analyzed by biomarker subgroups. T-DM1 was also tested on cell lines and in breast cancer xenograft models containing PIK3CA mutations.

RESULTS

Longer progression-free survival (PFS) and overall survival (OS) were observed with T-DM1 compared with capecitabine plus lapatinib in all biomarker subgroups. PIK3CA mutations were associated with shorter median PFS (mutant vs. wild type: 4.3 vs. 6.4 months) and OS (17.3 vs. 27.8 months) in capecitabine plus lapatinib-treated patients, but not in T-DM1-treated patients (PFS, 10.9 vs. 9.8 months; OS, not reached in mutant or wild type). T-DM1 showed potent activity in cell lines and xenograft models with PIK3CA mutations.

CONCLUSIONS

Although other standard HER2-directed therapies are less effective in tumors with PI3KCA mutations, T-DM1 appears to be effective in both PI3KCA-mutated and wild-type tumors. Clin Cancer Res; 22(15); 3755-63. ©2016 AACR.

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.

Anticancer Drug Delivery: An Update on Clinically Applied Nanotherapeutics

The development of chemotherapy using conventional anticancer drugs has been hindered due to several drawbacks related to their poor water solubility and poor pharmacokinetics, leading to severe adverse side effects and multidrug resistance in patients. Nanocarriers were developed to palliate these problems by improving drug delivery, opening the era of nanomedicine in oncology. Liposomes have been by far the most used nanovectors for drug delivery, with liposomal doxorubicin receiving US FDA approval as early as 1995. Antibody drug conjugates and promising drug delivery systems based on a natural polymer, such as albumin, or a synthetic polymer, are currently undergoing advanced clinical trials or have received approval for clinical applications. However, despite attractive results being obtained in preclinical studies, many well-designed nanodrugs fell short of expectations when tested in patients, evidencing the gap between nanoparticle design and their clinical translation. The aim of this review is to evaluate the extent of nanotherapeutics used in oncology by providing an insight into the most successful concepts. The reasons that prevent nanodrugs from expanding to clinic are discussed, and the efforts that must be taken to take full advantage of the great potential of nanomedicine are highlighted.

Drug-induced hepatotoxicity in cancer patients - implication for treatment

INTRODUCTION

All anticancer drugs can cause idiosyncratic liver injury. Therefore, hepatoprotective agents assume particular importance to preserve liver function. Hepatic injury represents 10% of cases of acute hepatitis in adults; drug-related damage is still misjudged because of relative clinical underestimation and difficult differential diagnosis. Chemotherapeutic agents can produce liver toxicity through different pathways, resulting in different categories of liver injuries, but these drugs are not homogeneously hepatotoxic. Frequently, anticancer-induced hepatotoxicity is idiosyncratic and influenced by multiple factors.

AREAS COVERED

The aim of this paper is to perform a review of the literature regarding anticancer-induced liver toxicity. We described hepatotoxicity mechanisms of principal anticancer agents and respective dose reductions. Furthermore, we reviewed studies on hepatoprotectors and their optimal use. Tiopronin, magnesium isoglycyrrhizinate and S-Adenosylmethionine (AdoMet) demonstrated, in some small studies, a potential hepatoprotective activity.

EXPERT OPINION

Actually, in the literature only small experiences are reported. Even though hepatoprotective agents seem to be useful in the oncologic setting, the lack of well-designed prospective Phase III randomized controlled trials is a major limit in the introduction of hepatoprotectors in cancer patients and these kind of studies are warranted to support their use and to give further recommendations for the clinical practice.

Antibody-Targeted Chemotherapy for the Treatment of Melanoma

Antibody-directed chemotherapy (ADC) offers an advantage over conventional chemotherapy because it provides antibody-directed targeting, with resultant improvement in therapeutic efficacy and reduced toxicity. Despite extensive research, with notable exceptions, broad clinical application of ADC remains elusive; major hurdles include the instability of antibody-chemotherapy linkers and reduced tumor toxicity of the chemotherapy when bound to the antibody. To address these challenges, we have developed a platform technology that utilizes the nab-paclitaxel formulation of paclitaxel, Abraxane, in which hydrophobic paclitaxel is suspended in 130-nm albumin nanoparticles and thus made water-soluble. We have developed a method to noncovalently coat the Abraxane nanoparticle with recombinant mAbs (anti-VEGF, bevacizumab) and guide Abraxane delivery into tumors in a preclinical model of human A375 melanoma. Here, we define the binding characteristics of bevacizumab and Abraxane, demonstrate that the chemotherapy agent retains its cytotoxic effect, while the antibody maintains the ability to bind its ligand when the two are present in a single nanoparticle (AB160), and show that the nanoparticle yields improved antitumor efficacy in a preclinical human melanoma xenograft model. Further data suggest that numerous therapeutic monoclonal IgG1 antibodies may be utilized in this platform, which has implications for many solid and hematologic malignancies. Cancer Res; 76(13); 3954-64. ©2016 AACR.

Safety and Efficacy of Trastuzumab Emtansine in Advanced Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer: a Meta-analysis

Advanced or metastatic breast cancer is an incurable disease with high mortality rate worldwide and about 20% of breast cancers overexpress and amplify the human epidermal growth factor receptor 2 (HER2). Achievements in targeted therapy have benefited people during the past decades. Trastuzumab emtansine (T-DM1), a novel antibody-drug conjugate playing a powerful role in anti-tumor activity, not only blocks the HER2 signaling pathways, but also disturbs the microtubule dynamics. To access the efficacy and safety of T-DM1, we analyzed 9 clinical trials on T-DM1. Results showed that fatigue (0.604, 95% CI 0.551, 0.654), nausea (0.450, 95% CI 0.365, 0.537), increased transaminases (0.425, 95% CI 0.353, 0.500) and thrombocytopenia (0.383, 95% CI 0.322, 0.448) occurred more frequently in participants with single T-DM1. In controlled trials, increased transaminases (OR = 4.040, 95% CI 1.429, 11.427), thrombocytopenia (OR = 8.500, 95% CI 3.964, 18.226) and fatigue (OR = 1.288, 95% CI 1.041, 1.593) were statistically significant. Only thrombocytopenia appeared as severe adverse event (grade ≥ 3) in single-arm and control-arm studies. Meanwhile, T-DM1 stabilized cancer and prolonged life with notable improved progression-free survival (PFS) and overall survival (OS). In conclusion, it is a safe and effective agent in advanced or metastatic breast cancer, but should be carefully applied on patients with severe hepatic and neurological disease.

Autophagy and Apoptotic Crosstalk: Mechanism of Therapeutic Resistance in HER2-Positive Breast Cancer

While breast cancer patients benefit from the use of HER2 inhibitors, many fail therapy and become resistant to treatment, indicating a critical need to prevent treatment failure. A number of studies have emerged that highlight the catabolic process of autophagy in breast cancer as a mechanism of resistance to chemotherapy and targeted inhibitors. Furthermore, recent research has begun to dissect how autophagy signaling crosstalks with apoptotic signaling. Thus, a possible strategy in fighting resistance is to couple targeting of apoptotic and autophagy signaling pathways. In this review, we discuss how cellular response by autophagy circumvents cell death to promote resistance of breast cancers to HER2 inhibitors, as well as the potential avenues of therapeutic intervention.

Clinical efficacy and safety of T-DM1 for patients with HER2-positive breast cancer

Purpose

The aim of this study was to evaluate the therapeutic efficacy and safety of trastuzumab emtansine (T-DM1) for the treatment of patients with human epidermal growth factor receptor 2-positive breast cancer.

Methods

We performed a systemic review and meta-analysis of the relevant published clinical studies. A computerized search was performed for controlled clinical trials of T-DM1 in targeted treatment. Overall survival, progression-free survival, objective response rate, symptom progression free, and adverse events (AEs) were evaluated.

Results

Eight eligible trials with a total of 2,016 patients with breast cancer were included in the present meta-analysis. The treatment of patients with breast cancer with T-DM1 was associated with significantly increased overall and progression-free survival when compared with controls (P<0.0001). An analysis of the objective response rate and symptom progression free also demonstrated favorable results for T-DM1 treatment (P≤0.0001). There was no significant difference between the T-DM1 and control groups with respect to nonhematologic or hematologic AEs (P=0.99 and P=0.30, respectively).

Conclusion

Overall, T-DM1 is efficacious in the treatment of patients with human epidermal growth factor receptor 2-positive breast cancer and low rates of AEs compared with controls.

Reinvention of chemotherapy: drug conjugates and nanoparticles

PURPOSE OF REVIEW

Recent advances in nanotechnology have addressed some of the issues related to lack of selectivity and nonspecific toxicities associated with conventional chemotherapy. Nanoparticles are therapeutic carriers that can be fine tuned for specific application and for passive or active tumor targeting.

RECENT FINDINGS

Although the nanoparticle field is rapidly expanding, there are to date only six nanoparticle-based drug delivery platforms and two antibody-drug conjugates that are clinically approved for cancer therapy. Here, we review the clinical data of liposomal anthracyclines, nanoparticle formulations of paclitaxel and trastuzumab emtansine. We then briefly comment on efficacy and safety issues of nanoparticles, as well as on the next-generation nanoparticles for cancer therapy.

SUMMARY

The emerging development of cancer nanotechnology offers the opportunity of reinvestigating the potential of cytotoxic agents, improving tumor targeting and drug delivery, leading to better safety profile and antitumor activity. Adding specificity to nanoparticles may allow personalization of cancer therapy using chemotherapy.

The future of antiviral immunotoxins

There is a constant need for new therapeutic interventions in a wide range of infectious diseases. Over the past few years, the immunotoxins have entered the stage as promising antiviral treatments. Immunotoxins have been extensively explored in cancer treatment and have achieved FDA approval in several cases. Indeed, the design of new anticancer immunotoxins is a rapidly developing field. However, at present, several immunotoxins have been developed targeting a variety of different viruses with high specificity and efficacy. Rather than blocking a viral or cellular pathway needed for virus replication and dissemination, immunotoxins exert their effect by killing and eradicating the pool of infected cells. By targeting a virus-encoded target molecule, it is possible to obtain superior selectivity and drastically limit the side effects, which is an immunotoxin-related challenge that has hindered the success of immunotoxins in cancer treatment. Therefore, it seems beneficial to use immunotoxins for the treatment of virus infections. One recent example showed that targeting of virus-encoded 7 transmembrane (7TM) receptors by immunotoxins could be a future strategy for designing ultraspecific antiviral treatment, ensuring efficient internalization and hence efficient eradication of the pool of infected cells, both in vitro and in vivo. In this review, we provide an overview of the mechanisms of action of immunotoxins and highlight the advantages of immunotoxins as future anti-viral therapies.