Open-label phase II study evaluating the efficacy and safety of two doses of pertuzumab in castrate chemotherapy-naive patients with hormone-refractory prostate cancer

ERBB3 Overexpression is Enriched in Diverse Patient Populations with Castration-sensitive Prostate Cancer and is Associated with a Unique AR Activity Signature

PURPOSE

Despite successful clinical management of castration-sensitive prostate cancer (CSPC), the 5-year survival rate for men with castration-resistant prostate cancer is only 32%. Combination treatment strategies to prevent disease recurrence are increasing, albeit in biomarker-unselected patients. Identifying a biomarker in CSPC to stratify patients who will progress on standard-of-care therapy could guide therapeutic strategies.

EXPERIMENTAL DESIGN

Targeted deep sequencing was performed for the University of Illinois (UI) cohort (n = 30), and immunostaining was performed on a patient tissue microarray (n = 149). Bioinformatic analyses identified pathways associated with biomarker overexpression (OE) in the UI cohort, consolidated RNA sequencing samples accessed from Database of Genotypes and Phenotypes (n = 664), and GSE209954 (n = 68). Neutralizing antibody patritumab and ectopic HER3 OE were utilized for functional mechanistic experiments.

RESULTS

We identified ERBB3 OE in diverse patient populations with CSPC, where it was associated with advanced disease at diagnosis. Bioinformatic analyses showed a positive correlation between ERBB3 expression and the androgen response pathway despite low dihydrotestosterone and stable expression of androgen receptor (AR) transcript in Black/African American men. At the protein level, HER3 expression was negatively correlated with intraprostatic androgen in Black/African American men. Mechanistically, HER3 promoted enzalutamide resistance in prostate cancer cell line models and HER3-targeted therapy resensitized therapy-resistant prostate cancer cell lines to enzalutamide.

CONCLUSIONS

In diverse patient populations with CSPC, ERBB3 OE was associated with high AR signaling despite low intraprostatic androgen. Mechanistic studies demonstrated a direct link between HER3 and enzalutamide resistance. ERBB3 OE as a biomarker could thus stratify patients for intensification of therapy in castration-sensitive disease, including targeting HER3 directly to improve sensitivity to AR-targeted therapies.

The prevalence and clinical significance of HER2 expression in prostate adenocarcinoma

AIMS

Abnormalities in HER2 are well-established oncogenic drivers and are approved therapeutic targets in various malignancies. Prior studies evaluating HER2 expression in prostate cancer (PCa) have yielded variable results. Most of these studies used immunohistochemistry scoring systems based on breast cancer data. The goal of this study was to determine the prevalence and clinical significance of HER2 expression using a scoring system that better reflects the HER2 staining pattern observed in PCa.

METHODS

We randomly selected similar numbers of localized low risk (AJCC stage I), locally advanced (AJCC stages II & III), and metastatic (AJCC stage IV) PCa patients treated at the DC VA Medical Center between 2000 and 2022. Among them, we included patients who had sufficient PCa tissue samples and clinical information required for this analysis. Two experienced pathologists independently scored HER2 expression (Ventana Pathway anti-HER2) according to a modified gastric cancer HER2 scoring system.

RESULTS

Out of the 231 patients included, 85 % self-identified as Black. 58.9 % of patients expressed HER2 (1+: 35.5 %; 2+: 18.2 %; 3+: 5.2 %). Validity of the results was confirmed using the HercepTest antibody. Higher HER2 expression was associated with a higher Gleason Score/Grade Group and advanced disease.

CONCLUSIONS

Our findings support the adverse prognostic impact on HER2 in PCa. We propose the use of a modified scoring system to evaluate HER2 expression in PCa. The observed high prevalence of HER2 expression supports the consideration of novel HER2-targeted therapies addressing even low levels of HER2 expression in future PCa trials.

A bibliometric analysis of metastatic breast cancer: two-decade report (2002-2022)

Background

MBC is a lethal form of breast cancer that arises when cancer cells invade other organs or tissues. The treatment of MBC needs personalized approaches based on the tumor and patient characteristics. The purpose of this paper is to analyze MBC studies from 2002 to 2022 using bibliometrics and to investigate its current situation, main contributors, core journals, highly cited papers, and topic evolution.

Materials and methods

We retrieved data from Web of Science Core Collection (WOSCC). Bibliometric analysis of the included literatures mainly used the following tools: the function of "analyze results" and "citation report" in WoS, Microsoft excel 2021, CiteSpace v.6.1. R6, VOSviewer v.1.6.18, BICOMB v.2.04 and gCLUTO v.1.0.

Results

We found 12,653 articles on MBC research published in 1, 802 journals by 69, 753 authors from 118 countries. The annual output and citation of MBC articles showed a rising trend over time. The United States was the most influential country in MBC research. The most cited journal in this field was The Journal of Clinical Oncology. And the most cited article was by Slamon DJ. The co-word analysis of keywords divides MBC into six research clusters. The hormone receptor-positive MBC and liquid biopsy of MBC are the frontiers research trends. "CDK4/6 inhibitor" had the highest burst strength.

Conclusion

Our bibliometric analysis offers a comprehensive overview of MBC research in the past two decades. It shows the current situation, main contributors, core journals, highly cited papers, and topic evolution of this field. Our study can assist researchers and practitioners to comprehend the development and trends of MBC research and to discover potential directions for future research.

HER3 Is an Actionable Target in Advanced Prostate Cancer

It has been recognized for decades that ERBB signaling is important in prostate cancer, but targeting ERBB receptors as a therapeutic strategy for prostate cancer has been ineffective clinically. However, we show here that membranous HER3 protein is commonly highly expressed in lethal prostate cancer, associating with reduced time to castration resistance (CR) and survival. Multiplex immunofluorescence indicated that the HER3 ligand NRG1 is detectable primarily in tumor-infiltrating myelomonocytic cells in human prostate cancer; this observation was confirmed using single-cell RNA sequencing of human prostate cancer biopsies and murine transgenic prostate cancer models. In castration-resistant prostate cancer (CRPC) patient-derived xenograft organoids with high HER3 expression as well as mouse prostate cancer organoids, recombinant NRG1 enhanced proliferation and survival. Supernatant from murine bone marrow-derived macrophages and myeloid-derived suppressor cells promoted murine prostate cancer organoid growth in vitro, which could be reversed by a neutralizing anti-NRG1 antibody and ERBB inhibition. Targeting HER3, especially with the HER3-directed antibody-drug conjugate U3-1402, exhibited antitumor activity against HER3-expressing prostate cancer. Overall, these data indicate that HER3 is commonly overexpressed in lethal prostate cancer and can be activated by NRG1 secreted by myelomonocytic cells in the tumor microenvironment, supporting HER3-targeted therapeutic strategies for treating HER3-expressing advanced CRPC. SIGNIFICANCE: HER3 is an actionable target in prostate cancer, especially with anti-HER3 immunoconjugates, and targeting HER3 warrants clinical evaluation in prospective trials.

Tumor Microenvironment-Derived NRG1 Promotes Antiandrogen Resistance in Prostate Cancer

Despite the development of second-generation antiandrogens, acquired resistance to hormone therapy remains a major challenge in treating advanced prostate cancer. We find that cancer-associated fibroblasts (CAFs) can promote antiandrogen resistance in mouse models and in prostate organoid cultures. We identify neuregulin 1 (NRG1) in CAF supernatant, which promotes resistance in tumor cells through activation of HER3. Pharmacological blockade of the NRG1/HER3 axis using clinical-grade blocking antibodies re-sensitizes tumors to hormone deprivation in vitro and in vivo. Furthermore, patients with castration-resistant prostate cancer with increased tumor NRG1 activity have an inferior response to second-generation antiandrogen therapy. This work reveals a paracrine mechanism of antiandrogen resistance in prostate cancer amenable to clinical testing using available targeted therapies.

Microenvironment-Mediated Resistance to Anti-Androgen Therapy

In this issue of Cancer Cell, Zhang et al. expose new possibilities for targeting castration-resistant prostate cancer (CRPC). Activation of the HER2/HER3 axis by cancer-associated fibroblast-secreted NRG1 mediates castration resistance, recommending novel applications of clinical anti-NRG1/HER3 therapeutics in treating CRPC.

ErbB-2 signaling in advanced prostate cancer progression and potential therapy

Currently, prostate cancer (PCa) remains the most commonly diagnosed solid tumor and the second leading cause of cancer-related deaths in US men. Most of these deaths are attributed to the development of castration-resistant (CR) PCa. ErbB-2 and ErbB family members have been demonstrated to contribute to the progression of this lethal disease. In this review, we focus on updating the role of ErbB-2 in advanced PCa progression and its regulation, including its regulation via ligand activation, miRNAs and protein phosphorylation. We also discuss its downstream signaling pathways, including AKT, ERK1/2 and STATs, involved in advanced PCa progression. Additionally, we evaluate the potential of ErbB-2, focusing on its protein hyper-phosphorylation status, as a biomarker for aggressive PCa as well as the effectiveness of ErbB-2 as a target for the treatment of CR PCa via a multitude of approaches, including orally available inhibitors, intratumoral expression of cPAcP, vaccination and immunotherapy.

Potential Influence of Endothelial Adsorption on the Delayed Time to Maximum Concentration of Biopharmaceuticals

Background and objectives

Maximum plasma concentration of biopharmaceuticals sometimes occurs long after completion of intravenous infusion. The objective of this research was to study the hypothetical adsorption of biopharmaceuticals to endothelium and infusion material, which may theoretically explain this phenomenon.

Methods

Infusion procedures were mimicked in an artificial vessel covered with a confluent monolayer of endothelial cells. Three monoclonal antibodies (MAbs) and C1 inhibitor were studied.

Results

Adsorption of MAbs to endothelium was observed followed by release when the vessel was subsequently perfused with buffer. Adsorption to infusion material also occurred to various degrees and in a seemingly random fashion, with a loss of up to 15% during a single flush of the line, but release from the line was not seen.

Conclusions

Our results indicate that adsorption of biopharmaceuticals to endothelium can occur. This observation can explain the increase in plasma concentration after completion of intravenous administration.

O-Glycosylation-mediated signaling circuit drives metastatic castration-resistant prostate cancer

Disseminated castration-resistant prostate cancer (CRPC) is a common disease in men that is characterized by limited survival and resistance to androgen-deprivation therapy. The increase in human epidermal growth factor receptor 2 (HER2) signaling contributes to androgen receptor activity in a subset of patients with CRPC; however, enigmatically, HER2-targeted therapies have demonstrated a lack of efficacy in patients with CRPC. Aberrant glycosylation is a hallmark of cancer and involves key processes that support cancer progression. Using transcriptomic analysis of prostate cancer data sets, histopathologic examination of clinical specimens, and in vivo experiments of xenograft models, we reveal in this study a coordinated increase in glycan-binding protein, galectin-4, specific glycosyltransferases of core 1 synthase, glycoprotein- N-acetylgalactosamine 3-β-galactosyltransferase 1 (C1GALT1) and ST3 beta-galactoside α-2,3-sialyltransferase 1 (ST3GAL1), and resulting mucin-type O-glycans during the progression of CRPC. Furthermore, galectin-4 engaged with C1GALT1-dependent O-glycans to promote castration resistance and metastasis by activating receptor tyrosine kinase signaling and cancer cell stemness properties mediated by SRY-box 9 (SOX9). This galectin-glycan interaction up-regulated the MYC-dependent expression of C1GALT1 and ST3GAL1, which altered cellular mucin-type O-glycosylation to allow for galectin-4 binding. In clinical prostate cancer, high-level expression of C1GALT1 and galectin-4 together predict poor overall survival compared with low-level expression of C1GALT1 and galectin-4. In summary, MYC regulates abnormal O-glycosylation, thus priming cells for binding to galectin-4 and downstream signaling, which promotes castration resistance and metastasis.-Tzeng, S.-F., Tsai, C.-H., Chao, T.-K., Chou, Y.-C., Yang, Y.-C., Tsai, M.-H., Cha, T.-L., Hsiao, P.-W. O-Glycosylation-mediated signaling circuit drives metastatic castration-resistant prostate cancer.

Strategies for clinical development of monoclonal antibodies beyond first-in-human trials: tested doses and rationale for dose selection

BACKGROUND

Our previous survey on first-in-human trials (FIHT) of monoclonal antibodies (mAbs) showed that, due to their limited toxicity, the recommended phase II dose (RP2D) was only tentatively defined.

METHODS

We identified, by MEDLINE search, articles on single-agent trials of mAbs with an FIHT included in our previous survey. For each mAb, we examined tested dose(s) and dose selection rationale in non-FIHTs (NFIHTs). We also assessed the correlation between doses tested in the registration trials (RTs) of all FDA-approved mAbs and the corresponding FIHT results.

RESULTS

In the 37 dose-escalation NFIHTs, the RP2D indication was still poorly defined. In phase II-III NFIHTs (n=103 on 37 mAbs), the FIHT RP2D was the only dose tested for five mAbs. For 16 mAbs, only doses different from the FIHT RP2D or the maximum administered dose (MAD) were tested and the dose selection rationale infrequently indicated. In the 60 RTs on 27 FDA-approved mAbs with available FIHT, the FIHT RP2D was tested only for two mAbs, and RT doses were much lower than the FIHT MAD.

CONCLUSIONS

The rationale beyond dose selection in phase II and III trials of mAbs is often unclear in published articles and not based on FIHT data.

A Standardized Wedelia chinensis Extract Overcomes the Feedback Activation of HER2/3 Signaling upon Androgen-Ablation in Prostate Cancer

Crosstalk between the androgen receptor (AR) and other signaling pathways in prostate cancer (PCa) severely affects the therapeutic outcome of hormonal therapy. Although anti-androgen therapy prolongs overall survival in PCa patients, resistance rapidly develops and is often associated with increased AR expression and upregulation of the HER2/3-AKT signaling pathway. However, single agent therapy targeting AR, HER2/3 or AKT usually fails due to the reciprocal feedback loop. Previously, we reported that wedelolactone, apigenin, and luteolin are the active compounds in Wedelia chinensis herbal extract, and act synergistically to inhibit the AR activity in PCa. Here, we further demonstrated that an herbal extract of W. chinensis (WCE) effectively disrupted the AR, HER2/3, and AKT signaling networks and therefore enhanced the therapeutic efficacy of androgen ablation in PCa. Furthermore, WCE remained effective in suppressing AR and HER2/3 signaling in an in vivo adapted castration-resistant PCa (CRPC) LNCaP cell model that was insensitive to androgen withdrawal and second-line antiandrogen, enzalutamide. This study provides preclinical evidence that the use of a defined, single plant-derived extract can augment the therapeutic efficacy of castration with significantly prolonged progression-free survival. These data also establish a solid basis for using WCE as a candidate agent in clinical studies.

Androgen Signaling in Prostate Cancer

The androgen-signaling axis plays a pivotal role in the pathogenesis of prostate cancer. Since the landmark discovery by Huggins and Hodges, gonadal depletion of androgens has remained a mainstay of therapy for advanced disease. However, progression to castration-resistant prostate cancer (CRPC) typically follows and is largely the result of restored androgen signaling. Efforts to understand the mechanisms behind CRPC have revealed new insights into dysregulated androgen signaling and intratumoral androgen synthesis, which has ultimately led to the development of several novel androgen receptor (AR)-directed therapies for CRPC. However, emergence of resistance to these newer agents has also galvanized new directions in investigations of prereceptor and postreceptor AR regulation. Here, we review our current understanding of AR signaling as it pertains to the biology and natural history of prostate cancer.

Evolution of anti-HER2 therapies for cancer treatment

The development of HER2-directed monoclonal antibodies and tyrosine kinase inhibitors have provided benefits to cancer patients, as well as produced many insights into the biology of the ErbB receptor family. Current therapies based on ErbB family members have resulted in improved overall survival with associated improvements in quality of life for the cancer patients that respond to treatment. Compared to monotherapy using either two antibodies to block the HER2 receptor blockade or combinatorial approaches with HER2 antibodies and standard therapies has provided additional benefits. Despite the therapeutic success of existing HER2 therapies, personalising treatment and overcoming resistance to these therapies remains a significant challenge. The heterogeneous intra-tumoural HER2 expression and lack of fully predictive and prognostic biomarkers remain significant barriers to improving the use of HER2 antibodies. Imaging modalities using radiolabelled pertuzumab and trastuzumab allow quantitative assessment of intra-tumoural HER2 expression, HER2 antibody saturation and the success of different drug delivery systems to be assessed. Molecular imaging with HER2 antibodies has the potential to be a non-invasive, predictive and prognostic technique capable of influencing therapeutic decisions, predicting response and failure of treatments as well as providing insights into receptor recycling and signalling. Similarly, conjugating HER2 antibodies with novel toxic payloads or combining HER2 antibodies with cellular immunotherapy provide exciting new opportunities for the management of tumours overexpressing HER2. Future research will lead to higher therapeutic responses, lower toxicities and providing insight into the mechanisms of resistance to HER2-targeted treatments.

Transcriptional response profiles of paired tumor-normal samples offer novel perspectives in pan-cancer analysis

Both tumor and adjacent normal tissues are valuable in cancer research. Transcriptional response profiles represent the changes of gene expression levels between paired tumor and adjacent normal tissues. In this study, we performed a pan-cancer analysis based on the transcriptional response profiles from 633 samples across 13 cancer types. We obtained two interesting results. Using consensus clustering method, we characterized ten clusters with distinct transcriptional response patterns and enriched pathways. Notably, head and neck squamous cell carcinoma was divided in two subtypes, enriched in cell cycle-related pathways and cell adhesion-related pathways respectively. The other interesting result is that we identified 92 potential pan-cancer genes that were consistently upregulated across multiple cancer types. Knockdown of FAM64A or TROAP inhibited the growth of cancer cells, suggesting that these genes may promote tumor development and are worthy of further validations. Our results suggest that transcriptional response profiles of paired tumor-normal tissues can provide novel perspectives in pan-cancer analysis.

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.

Glycoengineering of pertuzumab and its impact on the pharmacokinetic/pharmacodynamic properties

Pertuzumab is an antihuman HER2 antibody developed for HER2 positive breast cancer. Glycosylation profiles are always the important issue for antibody based therapy. Previous findings have suggested the impact of glycosylation profiles on the function of antibodies, like pharmacodynamics, antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC). However, the roles of fucose and sialic acid in the function of therapeutic antibodies still need further investigation, especially the role of sialic acid in nonfucosylated antibodies. This study focused on the pharmacokinetic and pharmacodynamic properties of pertuzumab after glycoengineering. Herein, nonfucosylated pertuzumab was produced in CHO^FUT8−/− cells, and desialylated pertuzumab was generated by enzymatic hydrolysis. Present data indicated that fucose was critical for ADCC activity by influencing the interaction between pertuzumab and FcγRIIIa, nevertheless removal of sialic acid increased the ADCC and CDC activity of pertuzumab. Meanwhile, regarding to sialic acid, sialidase hydrolysis directly resulted in asialoglycoprotein receptors (ASGPRs) dependent clearance in hepatic cells in vitro. The pharmacokinetic assay revealed that co-injection of asialofetuin can protect desialylated pertuzumab against ASGPRs-mediated clearance. Taken together, the present study elucidated the importance of fucose and sialic acid for pertuzumab, and also provided further understanding of the relationship of glycosylation/pharmacokinetics/pharmacodynamics of therapeutic antibody.

ErbB2 Signaling Increases Androgen Receptor Expression in Abiraterone-Resistant Prostate Cancer

PURPOSE

ErbB2 signaling appears to be increased and may enhance androgen receptor (AR) activity in a subset of patients with castration-resistant prostate cancer (CRPC), but agents targeting ErbB2 have not been effective. This study was undertaken to assess ErbB2 activity in abiraterone-resistant prostate cancer and to determine whether it may contribute to AR signaling in these tumors.

EXPERIMENTAL DESIGN

AR activity and ErbB2 signaling were examined in the radical prostatectomy specimens from a neoadjuvant clinical trial of leuprolide plus abiraterone and in the specimens from abiraterone-resistant CRPC xenograft models. The effect of ErbB2 signaling on AR activity was determined in two CRPC cell lines. Moreover, the effect of combination treatment with abiraterone and an ErbB2 inhibitor was assessed in a CRPC xenograft model.

RESULTS

We found that ErbB2 signaling was elevated in residual tumor following abiraterone treatment in a subset of patients and was associated with higher nuclear AR expression. In xenograft models, we similarly demonstrated that ErbB2 signaling was increased and associated with AR reactivation in abiraterone-resistant tumors. Mechanistically, we show that ErbB2 signaling and subsequent activation of the PI3K/AKT signaling stabilizes AR protein. Furthermore, concomitantly treating CRPC cells with abiraterone and an ErbB2 inhibitor, lapatinib, blocked AR reactivation and suppressed tumor progression.

CONCLUSIONS

ErbB2 signaling is elevated in a subset of patients with abiraterone-resistant prostate cancer and stabilizes AR protein. Combination therapy with abiraterone and ErbB2 antagonists may be effective for treating the subset of CRPC with elevated ErbB2 activity. Clin Cancer Res; 22(14); 3672-82. ©2016 AACR.

Persistent androgen receptor addiction in castration-resistant prostate cancer

It is now understood that persistent activation of the androgen receptor (AR) signaling pathway often underlies the development of castration-resistant prostate cancer (CRPC). This realization led to renewed interest in targeting the AR and ultimately to the development of the potent next-generation AR-directed agents abiraterone and enzalutamide. While these drugs prolong survival in men with CRPC, they are unfortunately not curative. Perhaps not surprisingly, evidence points to persistent AR signaling as one of the key drivers by which resistances to these agents develops. In this context, activation of the AR signaling program can occur through a number of molecular adaptations, including alterations leading to persistent canonical AR signaling (e.g., AR amplification/overexpression, elucidations/concentration of intratumoral androgens), activation of the AR program via feedback pathways (e.g., AKT/mTOR/Pi3K, HER2/Neu), and activation of the AR program via mutation or substitution (e.g., AR ligand binding domain mutation; AR splice variants; glucocorticoid receptor signaling). This review will provide an overview of the more clinical relevant (i.e., druggable) pathways that have been implicated in the emergence of drug resistance in men with CRPC and highlight some of the ongoing efforts towards developing therapeutics to impair these mechanisms.

The level of HER2 expression is a predictor of antibody-HER2 trafficking behavior in cancer cells

The receptor tyrosine kinase HER2 is known to play a central role in mitogenic signaling, motivating the development of targeted, HER2-specific therapies. However, despite the longstanding use of antibodies to target HER2, controversies remain concerning antibody/HER2 trafficking behavior in cancer cells. Understanding this behavior has direct relevance to the mechanism of action and effective design of such antibodies. In the current study, we analyzed the intracellular dynamics of trastuzumab, a marketed HER2-targeting antibody, in a panel of breast and prostate cancer cell lines that have a wide range of HER2 expression levels. Our results reveal distinct post-endocytic trafficking behavior of antibody-HER2 complexes in cells with different HER2 expression levels. In particular, HER2-overexpressing cells exhibit efficient HER2 recycling and limited reductions in HER2 levels upon antibody treatment, and consequently display a high level of antibody persistence on their plasma membrane. By contrast, in cells with low HER2 expression, trastuzumab treatment results in rapid antibody clearance from the plasma membrane combined with substantial decreases in HER2 levels and undetectable levels of recycling. A cell line with intermediate levels of HER2 expression exhibits both antibody recycling and clearance from the cell surface. Significantly, these analyses demonstrate that HER2 expression levels, rather than cell origin (breast or prostate), is a determinant of subcellular trafficking properties. Such studies have relevance to optimizing the design of antibodies to target HER2.

[Pertuzumab and solid tumors: perspectives]

Over the past decade, trastuzumab was the only available monoclonal anti-HER2 antibody for the treatment of HER2 positive breast and gastric cancer. Recently, pertuzumab added to docetaxel and trastuzumab showed dramatic overall survival improvement in first line treatment of HER2 positive metastatic breast cancer. Pertuzumab is the first approved monoclonal antibody in a new class of drugs called dimerization inhibitors. This agent was also approved in association with trastuzumab for neoadjuvant HER2-positive breast cancer treatment. However, pertuzumab development was not confined to breast cancer and in the present review, we will focus on biological rational, preclinical data and clinical trial results of pertuzumab in solid tumors excluding breast cancer.

Antibody targeting of HER2/HER3 signaling overcomes heregulin-induced resistance to PI3K inhibition in prostate cancer

Dysregulated expression and/or mutations of the various components of the phosphoinositide 3-kinase (PI3K)/Akt pathway occur with high frequency in prostate cancer and are associated with the development and progression of castration resistant tumors. However, small molecule kinase inhibitors that target this signaling pathway have limited efficacy in inhibiting tumor growth, primarily due to compensatory survival signals through receptor tyrosine kinases (RTKs). Although members of the epidermal growth factor receptor (EGFR), or HER, family of RTKs are strongly implicated in the development and progression of prostate cancer, targeting individual members of this family such as EGFR or HER2 has resulted in limited success in clinical trials. Multiple studies indicate a critical role for HER3 in the development of resistance against both HER-targeted therapies and PI3K/Akt pathway inhibitors. In this study, we found that the growth inhibitory effect of GDC-0941, a class I PI3K inhibitor, is markedly reduced in the presence of heregulin. Interestingly, this effect is more pronounced in cells lacking phosphatase and tensin homolog function. Heregulin-mediated resistance to GDC-0941 is associated with reactivation of Akt downstream of HER3 phosphorylation. Importantly, combined blockade of HER2 and HER3 signaling by an anti-HER2/HER3 bispecific antibody or a mixture of anti-HER2 and anti-HER3 antibodies restores sensitivity to GDC-0941 in heregulin-treated androgen-dependent and -independent prostate cancer cells. These studies indicate that the combination of PI3K inhibitors with HER2/HER3 targeting antibodies may constitute a promising therapeutic strategy for prostate cancer.

Randomized Phase II trial of nintedanib, afatinib and sequential combination in castration-resistant prostate cancer

AIMS

The aim of this article was to evaluate afatinib (BIBW 2992), an ErbB family blocker, and nintedanib (BIBF 1120), a triple angiokinase inhibitor, in castration-resistant prostate cancer patients.

PATIENTS & METHODS

Patients were randomized to receive nintedanib (250 mg twice daily), afatinib (40 mg once daily [q.d.]), or alternating sequential 7-day nintedanib (250 mg twice daily) and afatinib (70 mg q.d. [Combi70]), which was reduced to 40 mg q.d. (Combi40) due to adverse events. The primary end point was progression-free rate at 12 weeks.

RESULTS

Of the 85 patients treated 46, 20, 16 and three received nintedanib, afatinib, Combi40 and Combi70, respectively. At 12 weeks, the progression-free rate was 26% (seven out of 27 patients) for nintedanib, and 0% for afatinib and Combi40 groups. Two patients had a ≥50% decline in PSA (nintedanib and the Combi40 groups). The most common drug-related adverse events were diarrhea, nausea, vomiting and lethargy.

CONCLUSION

Nintedanib and/or afatinib demonstrated limited anti-tumor activity in unselected advanced castration-resistant prostate cancer patients.

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

Fifteen to 20% of breast cancers display HER2 amplification. Many therapeutic successes have been obtained for this subtype in the last decade since trastuzumab approval for metastatic and localized diseases. Pertuzumab, a new anti-HER2 antibody, has been approved in 2013 by the European Medicine Agency. This drug can be used in combination with trastuzumab and docetaxel for the first line treatment of metastatic or locally recurrent non resecable HER2-positive breast cancers not previously treated by chemotherapy or HER2-inhibitors in the metastatic setting. This approval has been done after the CLEOPATRA trial results. This was a randomized, double-blind, multicentre, phase III trial evaluating the standard treatment (trastuzumab plus docetaxel) associated to pertuzumab or placebo. The authors have reported a statistically significant and clinically relevant benefit for the pertuzumab-based treatment. Median progression-free survival was 18.4 for the pertuzumab arm versus 12.5 months for the control group (p<0.001). They also observed benefits concerning the secondary endpoints: overall response rate and overall survival. Patients receiving pertuzumab presented more frequent diarrhea and febrile neutropenia but no increase in cardiac events. This drug has already been evaluated in the neoadjuvant setting with a FDA approval recently obtained. Its use in the adjuvant setting is under evaluation.

A phase IIa dose-finding and safety study of first-line pertuzumab in combination with trastuzumab, capecitabine and cisplatin in patients with HER2-positive advanced gastric cancer

BACKGROUND

Pertuzumab plus trastuzumab provides a more comprehensive blockade of HER2 signalling than trastuzumab alone. Therefore, we conducted a phase IIa study of the pharmacokinetics and safety of pertuzumab plus trastuzumab and chemotherapy in advanced gastric cancer (aGC).

METHODS

Patients received pertuzumab 840 mg for cycle 1 and 420 mg q3w for cycles 2-6 (Arm A) or pertuzumab 840 mg q3w for six cycles (Arm B). Trastuzumab, cisplatin and capecitabine were also given for six cycles, then trastuzumab q3w until disease progression or unmanageable toxicity. The co-primary endpoints were day 43 pertuzumab serum trough concentration (Cmin) and safety.

RESULTS

Thirty patients were randomised. Mean pertuzumab Cmin at day 43 was 40.0 μg ml(-1) (s.d.: 17.3) in Arm A and 62.7 μg ml(-1) (29.1) in Arm B. Mean day 43 Cmin in Arm A was ~37% lower than that seen in metastatic breast cancer. The safety profiles were similar between arms and treatment was well tolerated. Partial responses were achieved by 86% and 55% of patients in Arms A and B, respectively.

CONCLUSIONS

On the basis of the pharmacokinetic and safety data, the 840 mg q3w pertuzumab dose has been selected for a phase III study of pertuzumab, trastuzumab and chemotherapy in HER2-positive aGC.

The European Medicines Agency Review of Pertuzumab for the treatment of adult patients with HER2-positive metastatic or locally recurrent unresectable breast cancer: summary of the scientific assessment of the committee for medicinal products for human use

Pertuzumab is a recombinant humanized monoclonal antibody that specifically targets the extracellular dimerization domain (subdomain II) of HER2. Based on the positive opinion from the European Medicines Agency (EMA) on March 4, 2013, a marketing authorization valid throughout the European Union (EU) was issued for pertuzumab (Perjeta) for use in combination with trastuzumab and docetaxel for the treatment of adult patients with HER2-positive metastatic or locally recurrent unresectable breast cancer who have not received previous anti-HER2 therapy or chemotherapy for their metastatic disease. The demonstration of clinical benefit for pertuzumab was based on a single, phase III, randomized, double-blind, placebo-controlled trial comparing the efficacy and safety of pertuzumab plus trastuzumab plus docetaxel versus placebo plus trastuzumab plus docetaxel in previously untreated patients with locally advanced or metastatic HER2-positive breast cancer. In the primary analysis, median progression-free survival was 18.5 months in the pertuzumab group compared with 12.4 months in the placebo group (hazard ratio [HR]: 0.62; 95% confidence interval [CI]: 0.51-0.75; p < .0001). For the secondary endpoints, overall survival (HR: 0.66; 95% CI: 0.52-0.84; p = .0008) and objective response rate (80.2% vs. 69.3%) were also favored in the pertuzumab group. Toxicity was similar between groups except for higher incidence of diarrhea, rash, mucosal inflammation, dry skin, and neutropenia for pertuzumab compared with placebo. This paper summarizes the scientific review of the application leading to approval in the EU. The detailed scientific assessment report and product information, including the summary of product characteristics, are available on the EMA website (http://www.ema.europa.eu).

Immunologic biomarkers in prostate cancer: the AE37 paradigm

One major achievement in cancer therapy is to select patients who will most likely benefit from a specific treatment. Predictive biomarkers play an important role in this respect being already useful in management of breast cancer and melanoma. For example, HER-2/neu (HER-2) overexpression selects for breast cancer patients to be treated with trastuzumab, and BRAFV600E mutations select for melanoma patients to be treated with vemurafenib. Identification of factors associated with T cell responsiveness to vaccination remains critical. Pre-existent immunity and circulating suppressor cells may regulate the levels of vaccine-specific T cell immunity after vaccination. The identification of immunologic endpoints to immunotherapy would thus considerably help guide the development of immunotherapy-based clinical trials. This commentary is based on a retrospective analysis we performed of data from prostate cancer patients vaccinated and boosted with the AE37 vaccine. The aim of these exploratory analyses was to identify factors useful in predicting which patients are more likely to respond to the treatment under study. The issue we are addressing here is to which extent common variables used pre- and/or following vaccinations with AE37 to assess the immune response status of the prostate cancer patients, may predict overall survival.

Constitutive activity of the androgen receptor

Prostate cancer (PCa) is the most frequently diagnosed cancer in the United States. The androgen receptor (AR) signaling axis is central to all stages of PCa pathophysiology and serves as the main target for endocrine-based therapy. The most advanced stage of the disease, castration-resistant prostate cancer (CRPC), is presently incurable and accounts for most PCa mortality. In this chapter, we highlight the mechanisms by which the AR signaling axis can bypass endocrine-targeted therapies and drive progression of CRPC. These mechanisms include alterations in growth factor, cytokine, and inflammatory signaling pathways, altered expression or activity of transcriptional coregulators, AR point mutations, and AR gene amplification leading to AR protein overexpression. Additionally, we will discuss the mechanisms underlying the synthesis of constitutively active AR splice variants (AR-Vs) lacking the COOH-terminal ligand-binding domain, as well as the role and regulation of AR-Vs in supporting therapeutic resistance in CRPC. Finally, we summarize the ongoing development of inhibitors targeting discrete AR functional domains as well as the status of new biomarkers for monitoring the AR signaling axis in patients.

Immunohistochemical expression of PDGFR, VEGF-C, and proteins of the mToR pathway before and after androgen deprivation therapy in prostate carcinoma: significant decrease after treatment

Targeted therapy in hormone refractory prostate cancer (HRPC) is currently under evaluation in many trials. The effect of androgen deprivation therapy (ADT) on many targets in prostate cancer is incompletely known. For the first time, immunohistochemical expression of the platelet-derived growth factor receptor (PDGFR), epidermal growth factor receptor (EGFR), vascular endothelial growth factor C (VEGF-C), mammalian target of rapamycin (mToR), p70 ribosomal protein S6 kinase 1 (PS6K), human epidermal growth factor receptor 2 (c-erbB-2), and carbonic anhydrase IX (CA9) was evaluated in 44 patients with prostate carcinoma treated with or without ADT, at biopsy time and after radical prostatectomy. PDGFR, VEGF-C, mToR, and PS6K expression was significantly reduced (p = 0.002, p = 0.035, p = 0.025, and p = 0.033, respectively) after ADT, whereas expression of EGFR, c-erbB-2, and CA9 was not influenced by ADT. In conclusion, targeting PDGFR, VEGF-C, mToR, or PS6K after ADT should be considered with precaution, as those targets can severely be altered or functionally deregulated by ADT.

Mechanisms of androgen receptor activation in castration-resistant prostate cancer

Systemic treatment of advanced prostate cancer is initiated with androgen deprivation therapy by gonadal testosterone depletion. Response durations are variable and tumors nearly always become resistant as castration-resistant prostate cancer (CRPC), which is driven, at least in part, by a continued dependence on the androgen receptor (AR). The proposed mechanisms that underlie AR function in this clinical setting are quite varied. These include intratumoral synthesis of androgens from inactive precursors, increased AR expression, AR activation through tyrosine kinase-dependent signaling, alterations in steroid receptor coactivators, and expression of a truncated AR with constitutive activity. Various pharmacologic interventions have clinically validated some of these mechanisms, such as those that require the AR ligand-binding domain. Clinical studies have failed to validate other mechanisms, and additional mechanisms have yet to be tested in patients with CRPC. Here, we review the mechanisms that elicit AR activity in CRPC, with a particular focus on recent developments.

Emerging paradigms in cardiomyopathies associated with cancer therapies

The cardiovascular care of cancer patients (cardio-oncology) has emerged as a new discipline in clinical medicine, given recent advances in cancer therapy, and is driven by the cardiovascular complications that occur as a direct result of cancer therapy. Traditional therapies such as anthracyclines and radiation have been recognized for years to have cardiovascular complications. Less expected were the cardiovascular effects of targeted cancer therapies, which were initially thought to be specific to cancer cells and would spare any adverse effects on the heart. Cancers are typically driven by mutations, translocations, or overexpression of protein kinases. The majority of these mutated kinases are tyrosine kinases, though serine/threonine kinases also play key roles in some malignancies. Several agents were developed to target these kinases, but many more are in development. Major successes have been largely restricted to agents targeting human epidermal growth factor receptor-2 (mutated or overexpressed in breast cancer), BCR-ABL (chronic myelogenous leukemia and some cases of acute lymphoblastic leukemia), and c-Kit (gastrointestinal stromal tumor). Other agents targeting more complex malignancies, such as advanced solid tumors, have had successes, but have not extended life to the degree seen with chronic myelogenous leukemia. Years before the first targeted therapy, Judah Folkman correctly proposed that to address solid tumors one had to target the inherent neoangiogenesis. Unfortunately, emerging evidence confirms that angiogenesis inhibitors cause cardiac complications, including hypertension, thrombosis, and heart failure. And therein lies the catch-22. Nevertheless, cardio-oncology has the potential to be transformative as the human cardiomyopathies that arise from targeted therapies can provide insights into the normal function of the heart.

AE37 peptide vaccination in prostate cancer: a 4-year immunological assessment updates on a phase I trial

In our recent phase I trial, we demonstrated that the AE37 vaccine is safe and induces HER-2/neu-specific immunity in a heterogeneous population of HER-2/neu (+) prostate cancer patients. Herein, we tested whether one AE37 boost can induce long-lasting immunological memory in these patients. Twenty-three patients from the phase I study received one AE37 boost 6-month post-primary vaccinations. Local/systemic toxicities were evaluated following the booster injection. Immunological responses were monitored 1-month (long-term booster; LTB) and 3-year (long-term immunity; LTI) post-booster by delayed-type hypersensitivity, IFN-γ ELISPOT and proliferation assays. Regulatory T cell (Treg) frequencies, plasma transforming growth factor-β (TGF-β) and indoleamine 2,3-deoxygenase (IDO) activity levels were also determined at the same time points. The AE37 booster was safe and well tolerated. Immunological monitoring revealed vaccine-specific long-term immunity in most of the evaluated patients during both LTB and LTI, although individual levels of immunity during LTI were decreased compared with those measured 3 years earlier during LTB. This was paralleled with increased Tregs, TGF-β levels and IDO activity. One AE37 booster generated long-term immunological memory in HER-2/neu (+) prostate cancer patients, which was detectable 3 years later, albeit with a tendency to decline. Boosted patients had favorable clinical outcome in terms of overall and/or metastasis-free survival compared with historical groups with similar clinical characteristics at diagnosis. We suggest that more boosters and/or concomitant disarming of suppressor circuits may be necessary to sustain immunological memory, and therefore, further studies to optimize the AE37 booster schedule are warranted.

Pertuzumab : evolving therapeutic strategies in the management of HER2-overexpressing breast cancer

INTRODUCTION

HER2 overexpression or amplification is present in approximately one-fifth of breast cancers and historically was associated with aggressive disease and poorer prognosis. The introduction of the humanized monoclonal antibody trastuzumab dramatically improved disease-free survival (DFS) and overall survival (OS) in this subgroup. As the majority of patients with metastatic disease ultimately develop resistance to trastuzumab, a need exists for more effective targeted therapies. Pertuzumab is an anti-HER2/neu-targeted therapy in the late stages of clinical development. The combination of pertuzumab, trastuzumab and docetaxel has been found to have an OS benefit in patients with HER2 positive metastatic breast cancer (MBC) when used in the first-line setting. This reflects a new standard of care, and pertuzumab was recently approved for this indication by the Food and Drug Administration (FDA). The efficacy of pertuzumab and trastuzumab in conjunction with chemotherapy is currently being evaluated in the adjuvant setting.

AREAS COVERED

This article provides an overview of preclinical investigations in addition to reviewing pertinent Phase I, Phase II and Phase III clinical trials.

EXPERT OPINION

Pertuzumab, in combination with the humanized monoclonal antibody trastuzumab, and docetaxel is a standard of care for patients with previously untreated metastatic breast cancer based on the CLEOPATRA study showing a survival benefit. There is no increase in cardiac toxicity with the combined HER2-targeted therapy. Future issues will address appropriate sequencing and combination with other anti-HER2-targeted therapies and/or chemotherapy.

HER2 Dimerization Inhibitor Pertuzumab - Mode of Action and Clinical Data in Breast Cancer

The humanized monoclonal antibody pertuzumab prevents the dimerization of HER2 with other HER receptors, in particular the pairing of the most potent signaling heterodimer HER2/HER3, thus providing a potent strategy for dual HER2 inhibition. It binds to the extracellular domain of HER2 at a different epitope than trastuzumab. Pertuzumab and trastuzumab act in a complementary fashion and provide a more complete blockade of HER2-mediated signal transduction than either agent alone. Phase II studies demonstrated that pertuzumab was generally well tolerated as a single agent or in combination with trastuzumab and/or cytotoxic agents, and implied an improved clinical efficacy of the combination of pertuzumab and trastuzumab in early and advanced HER2-positive breast cancer. Results of the pivotal phase III study CLEOPATRA in patients with HER2-positive metastatic breast cancer demonstrated that the addition of pertuzumab to first-line combination therapy with docetaxel and trastuzumab significantly prolonged progression-free and overall survival without increasing cardiac toxicity. Currently, the combination of both antibodies is being explored in the palliative setting as well as in the treatment of early HER2-positive breast cancer. Dual HER2 inhibition with the HER2 dimerization inhibitor pertuzumab and trastuzumab may change clinical practice in HER2-positive first-line metastatic breast cancer treatment.

Improved survival in a cohort of trial participants with metastatic castration-resistant prostate cancer demonstrates the need for updated prognostic nomograms

BACKGROUND

Median overall survival (OS) in men with metastatic castration-resistant prostate cancer (CRPC) was 13-16 mo in the predocetaxel era. Prognostic nomograms for survival estimation in CRPC were constructed prior to the introduction of docetaxel and other novel treatments.

OBJECTIVE

To examine whether prognostic models still accurately reflect survival in a large cohort of trial participants.

DESIGN, SETTING, AND PARTICIPANTS

Survival analysis of 442 men with CRPC sequentially treated in clinical trials at our institution from June 2003 to December 2011.

OUTCOME MEASURES AND STATISTICAL ANALYSIS

Predicted survival by Halabi and Smaletz nomograms was compared to observed survival. Cox model multivariate analysis (MVA) used variables at referral, including performance status (PS); levels of prostate-specific antigen (PSA), lactate dehydrogenase (LDH), alkaline phosphatase (ALP), haemoglobin (Hb), and albumin; presence of visceral disease, and metastatic disease at diagnosis.

RESULTS AND LIMITATIONS

From point of referral, chemotherapy-naïve patients had a median OS of 30.6 mo (95% confidence interval [CI], 27.6-36.5 mo). In contrast, predicted survival using the Halabi and Smaletz models was 21 and 18 mo, respectively. In these patients, poor PS, lower Hb level, and increasing LDH level were the strongest predictors in the MVA. In patients referred after chemotherapy, survival from referral was 17.5 mo (95% CI, 16.0-19.5 mo) and increasing LDH level and presence of visceral metastases were the strongest predictors of survival. Median OS from diagnosis of CRPC was 40.7 mo in the overall cohort (95% CI, 36.8-44.0 mo). Clinical trial participation was safe, with low mortality rate. This cohort of men participated in phase 1, 2 and 3 trials and expanded access programs; their data may not reflect survival in all CRPC patients.

CONCLUSIONS

Due to the impact of highly effective novel therapies on survival, prognostic nomograms in current use require revalidation regarding their ability to predict survival in CRPC.

Drug Monographs: Carfilzomib and Pertuzumab

The complexity of cancer chemotherapy requires pharmacists be familiar with the complicated regimens and highly toxic agents used. This column reviews various issues related to preparation, dispensing, and administration of antineoplastic therapy, and the agents, both commercially available and investigational, used to treat malignant diseases.

Tendencies for higher co-expression of EGFR and HER2 and downregulation of HER3 in prostate cancer lymph node metastases compared with corresponding primary tumors

The epidermal growth factor receptor (EGFR) family members are potential targets for therapy using extra-cellular domain receptor binding agents, such as the antibodies trastuzumab and cetuximab, or antibodies labeled with therapeutically useful radionuclides or toxins. This is especially the case when the tumor cells are resistant to chemotherapy and tyrosine kinase inhibitors. Studies concerning the expression of these receptors in prostate cancer vary in the literature, possibly due to differences in patient inclusion, sample preparations and scoring criteria. In our study, EGFR, HER2 and HER3 expression was analyzed in prostate cancer samples from primary tumors and corresponding lymph node metastases from 12 patients. The expression of HER2 and EGFR was scored from immunohistochemical preparations and the HercepTest criteria (0, 1+, 2+ or 3+), while HER3 expression was scored as no, weak or strong staining. There were 5 EGFR-positive (2+ or 3+) primary tumors and 6 EGFR-positive lymph node metastases, and there was EGFR upregulation in one metastasis. Only 4 of the 12 patients had marked HER2 expression (2+ or 3+) in their primary tumors and there was one downregulation and 5 cases of upregulation in the metastases. Thus, a total of 8 out of 12 analyzed metastases were HER2-positive. Of the 12 primary tumors, 9 expressed HER3 while only 2 of the lymph node metastases expressed recognizable HER3 staining, so 7 metastases appeared to have downregulated HER3 expression. In one of the primary tumors there was positive co-expression of EGFR and HER2, while this co-expression was observed in 4 of the metastases. Thus, there were tendencies for upregulation of HER2, increased co-expression of EGFR and HER2 and downregulation of HER3 in the prostate cancer lymph node metastases in comparison to the primary tumors. The results are encouraging for studies involving more patients. Possible strategies for EGFR- and HER2-targeted therapy are briefly discussed in the present study, especially with regard to the expression and co-expression of EGFR and HER2 in metastases.

Molecular mechanisms of cardiotoxicity induced by ErbB receptor inhibitor cancer therapeutics

The introduction of the so-called “targeted therapies”, particularly those drugs that inhibit the activity of tyrosine kinases, has represented a remarkable progress in the treatment of cancer. Although these drugs improve survival rates in cancer, significant cardiotoxicity, manifesting as left vertricular dysfunction and/or heart failure, has emerged. The ErbB receptor tyrosine kinases are being pursued as therapeutic targets because of their important roles in normal physiology and in cancer. Besides the fact that the ErbB receptors are indispensable during development and in normal adult physiology, epidermal growth factor (EGFR) and ErbB2 in particular have been implicated in the development of many human cancers. This review focuses on the rationale for targeting members of ErbB receptor family and numerous agents that are in use for inhibiting the pathway. We summarize the current knowledge on the physiological role of ErbB signaling in the ventricle and on structural aspects of ErbB receptor activation in cancer and cardiac cells. We examine the underlying mechanisms that result in on-target or off-target cardiotoxicities of ErbB inhibitors, which can influence the design of future anticancer therapies.

Management of metastatic castration-resistant prostate cancer: recent advances

Metastatic prostate cancer remains a considerable therapeutic challenge; however, advances in clinical research have resulted in five new treatments in the last 2 years. The immunotherapy sipuleucel-T, the cytotoxic cabazitaxel, the androgen biosynthesis inhibitor abiraterone acetate, the radioisotope alpharadin and the anti-androgen MDV3100 have all been shown to improve overall survival in randomized phase III studies for patients with metastatic castration-resistant prostate cancer. The therapeutic strategies of targeting androgen-receptor signalling and other key intracellular pathways involved in tumour progression and treatment resistance are yielding promising results. Agents such as the dual vascular endothelial growth factor receptor/MET inhibitor cabozantinib, the clusterin inhibitor custirsen and the Src inhibitor dasatinib have shown encouraging results in phase II studies. Novel immunotherapeutics such as prostate-specific membrane antigen-directed therapy and the anti-cytotoxic T lymphocyte-associated receptor 4 (CTLA4) antibody ipilimumab are also under investigation. Optimal methods of treatment selection, combination and sequencing have yet to be determined.

Risk of rash with the anti-HER2 dimerization antibody pertuzumab: a meta-analysis

Pertuzumab is a novel humanized monoclonal antibody that blocks human epidermal growth factor receptor 2 (HER2) dimerization. It was recently approved by the US FDA for use in combination with trastuzumab and docetaxel for patients with HER2-positive metastatic breast cancer who have not received prior anti-HER2 therapy or chemotherapy for metastatic disease. Rash is inconsistently reported as a common adverse event in most clinical trials of pertuzumab, at varying incidences. In this study, we have investigated the overall incidence and risk of rash with pertuzumab. Relevant studies were identified from the PubMed database (1966-2012), abstracts presented at the American Society of Clinical Oncology annual conference (2004-2011), and Web of Science database (1998-2012). Eligible studies were prospective phase II-III clinical trials using pertuzumab in cancer patients. Incidence, relative risk (RR), and 95 % confidence intervals (CIs) were calculated using random-effects or fixed-effects models based on the heterogeneity of included studies. Data from a total of 1,726 patients (pertuzumab, n = 1,157; controls, n = 569) with breast, ovarian, and prostate cancers from eight clinical trials were included for analysis. The incidence of all-grade and high-grade rash with pertuzumab were 24.6 % (95 % CI 19.3-30.8 %) and 1.1 % (95 % CI 0.5-2.2 %), respectively. The risk varied with tumor types, as patients with prostate cancer had a lower incidence of rash (13.2 %; 95 % CI 8.0-21.1 %) than those with breast, ovarian, fallopian tube, and peritoneal cancer (P = 0.001). Overall, pertuzumab significantly increased the risk of rash in comparison with controls (RR 1.53; 95 % CI 1.12-2.09; P = 0.007). Pertuzumab is associated with a significant risk of rash, and the incidence varies among different tumor types. Prevention, early recognition, and appropriate treatment of this rash may lead to improvement in patient quality of life, adherence to therapy, and possibly optimize clinical outcomes.

MicroRNAs as putative mediators of treatment response in prostate cancer

MicroRNAs (miRNAs) are an abundant class of noncoding RNAs that function to regulate post-transcriptional gene expression, predominantly by translational repression. In addition to their role in prostate cancer initiation and progression, recent evidence suggests that miRNAs might also participate in treatment response across a range of therapies including radiation treatment, chemotherapy and androgen suppression. The mechanism of this regulation is thought to be multifactorial and is currently poorly understood. To date, only a small number of studies have examined the functional role of miRNAs in response to prostate cancer treatment. Elucidating the role of miRNAs in treatment response following radiotherapy, chemotherapy and androgen suppression will provide new avenues of investigation for the development of novel therapies for the treatment of prostate cancer.

A phase Ib, dose-finding study of erlotinib in combination with a fixed dose of pertuzumab in patients with advanced non-small-cell lung cancer

BACKGROUND

Pertuzumab, a dimerization inhibitor of human epidermal growth factor receptor 2 (HER2), has demonstrated pharmacodynamic activity, with stable disease in non-small-cell lung cancer. Combining erlotinib and pertuzumab may enhance antitumor activity. This study aimed to establish the recommended dosing of the erlotinib and pertuzumab combination; assess safety, preliminary efficacy, and pharmacokinetics; and analyze biomarkers.

PATIENTS AND METHODS

Fifteen patients with stage IIIb/IV non-small-cell lung cancer who failed chemotherapy were recruited. The patients received erlotinib (days -8 to -1), then combination therapy (21-day cycles for 6 cycles). Pertuzumab was given intravenous at 840 mg, then 420 mg once every three weeks, with erlotinib given daily (100 or 150 mg).

RESULTS

No dose-limiting toxicities were observed. Adverse events were generally grade 1/2 and manageable. The objective response rate was 20% (3/15 patients; 2 responders had mutant HER1, 1 responder had wild-type HER1), median overall progression-free survival was 9.3 weeks. High HER1, HER2, and HER3 messenger RNA expression correlated with increased progression-free survival. Combination therapy did not affect erlotinib's pharmacokinetics; however, pertuzumab mean exposures (maximum concentration, 231 mg/L; area under the concentration-time curve from 0 to 21 days, 1780 mg*d/L) were slightly higher than in previous studies.

CONCLUSIONS

Combination therapy was well tolerated in patients with good performance status, with encouraging efficacy. A loading dose of pertuzumab 840 mg followed by 420 mg once every three weeks plus daily erlotinib 150 mg appears to be the most appropriate regimen for this combination.

Pooled analysis of cardiac safety in patients with cancer treated with pertuzumab

BACKGROUND

Pertuzumab, a human epidermal growth factor receptor (HER) 2 dimerization inhibitor, has demonstrated promising efficacy in combination with trastuzumab in patients with metastatic breast cancer. As HER signaling pathways are not only involved in oncogenesis, but also in myocardial homeostasis, an analysis of cardiac safety data was undertaken in a large group of patients treated with pertuzumab.

PATIENTS AND METHODS

A complete database of patients treated with full-dose pertuzumab was used to describe the incidence of asymptomatic left ventricular systolic dysfunction (LVSD) and symptomatic heart failure (HF).

RESULTS

Information for 598 unique patients was available for the current analysis. Of the patients treated with pertuzumab alone (n = 331) or pertuzumab in combination with a non-anthracycline-containing cytotoxic (n = 175) or trastuzumab (n = 93), 23 (6.9%), 6 (3.4%), and 6 (6.5%), respectively, developed asymptomatic LVSD and 1 (0.3%), 2 (1.1%), and 1 (1.1%), respectively, displayed symptomatic HF. None of the 15 patients receiving both pertuzumab and erlotinib demonstrated LVSD.

CONCLUSIONS

Patients treated with pertuzumab experienced relatively low levels of asymptomatic LVSD or symptomatic HF. There was no notable increase in cardiac side-effects when pertuzumab was given in combination with other anticancer agents.

Cardio-oncology in targeting the HER receptor family: the puzzle of different cardiotoxicities of HER2 inhibitors

The HER family of tyrosine kinase receptors includes several members that are clinically important targets in cancer therapies, in particular HER1 (the EGF receptor) and HER2, other members include HER3 and HER4. Trastuzumab, a humanized monoclonal antibody and lapatinib, a tyrosine kinase inhibitor, are drugs that target HER2, which is highly expressed in 20-30% of breast cancers. Trastuzumab is recommended as an adjuvant therapy for lymph node positive, HER2-positive breast cancers, or node-negative cancer with high-risk of recurrence, as well as in stage IV cancers. One serious side effect of trastuzumab is cardiomyocyte dysfunction, resulting in reduced heart contractile efficiency. The incidence of collateral effects on the heart with trastuzumab therapy increases in people with cardiovascular risk factors, heart disease and when combined with other chemotherapeutics. When cardiotoxicity was observed with trastuzumab, several studies have addressed potential cardiac damage of trastuzumab itself and lapatinib. The differences in cardiovascular effects of these two compounds are somewhat unexpected and suggest distinct mechanisms of action, which have clear implications in clinical application and prevention of cardiotoxicity in cardio-oncological approaches.

Small-molecule protein tyrosine kinase inhibitors for the treatment of metastatic prostate cancer

The microenvironment is critical to the growth of prostate cancer (PCa) in the bone. Thus, for clinical efficacy, therapies must target tumor-microenvironment interactions. Several protein tyrosine kinases have been implicated in the development and growth of PCa bone metastasis. In this review, specific protein tyrosine kinases that regulate these complex interactions, including PDGFR, the EGFR family, c-Src, VEGFR, IGF-1R, FGFR and c-Met will be discussed, with an emphasis on why these kinases are promising therapeutic targets for metastatic PCa treatment. For each of these kinases, small-molecule inhibitors have reached clinical trials. Current results of these trials and future prospects for the use of tyrosine kinase inhibitors for the treatment of PCa bone metastases are also discussed.

Genomic and epigenomic alterations in prostate cancer

Prostate cancer (PC) is the second most frequently diagnosed cancer and the second leading cause of cancer deaths in man. The treatment of localized PC includes surgery or radiation therapy. In case of relapse after a definitive treatment or in patients with locally advanced or metastatic disease, the standard treatment includes the androgen-deprivation therapy (ADT). By reducing the levels of testosterone and dihydrotestosterone under the castration threshold, the ADT acts on the androgen receptor (AR), even if indirectly. The effects of the ADT are usually temporary and nearly all patients, initially sensitive to the androgen ablation therapy, have a disease progression after an 18-24 months medium term. This is probably due to the selection of the cancer cell clones and to their acquisition of critical somatic genome and epigenomic changes. This review aims to provide an overview about the genetic and epigenetic alterations having a crucial role in the carcinogenesis and in the disease progression toward the castration resistant PC. We focused on the role of the AR, on its signaling cascade and on the clinical implications that the knowledge of these aspects would have on hormonal therapy, on its failure and its toxicity.

Castration-resistant prostate cancer: new science and therapeutic prospects

There is a growing number of new therapies targeting different pathways that will revolutionize patient management strategies in castration-resistant prostate cancer (CRPC) patients. Today there are more clinical trial options for CRPC treatment than ever before, and there are many promising agents in late-stage clinical testing. The hypothesis that CRPC frequently remains driven by a ligand-activated androgen receptor (AR) and that CRPC tissues exhibit substantial residual androgen levels despite gonadotropin-releasing hormone therapy, has led to the evaluation of new oral compounds such as abiraterone and MDV 3100. Their results, coupled with promising recent findings in immunotherapy (eg sipuleucel-T) and with agents targeting angiogenesis (while awaiting the final results of the CALGB trial 90401) will most probably impact the management of patients with CRPC in the near future. Other new promising agents need further development. With our increased understanding of the biology of this disease, further trial design should incorporate improved patient selection so that patient populations are those who may be most likely to benefit from treatment.