Randomized, double-blind, placebo-controlled phase II study of istiratumab (MM-141) plus nab-paclitaxel and gemcitabine versus nab-paclitaxel and gemcitabine in front-line metastatic pancreatic cancer (CARRIE)

HER3-targeted therapy: the mechanism of drug resistance and the development of anticancer drugs

Human epidermal growth factor receptor 3 (HER3), which is part of the HER family, is aberrantly expressed in various human cancers. Since HER3 only has weak tyrosine kinase activity, when HER3 ligand neuregulin 1 (NRG1) or neuregulin 2 (NRG2) appears, activated HER3 contributes to cancer development and drug resistance by forming heterodimers with other receptors, mainly including epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2). Inhibition of HER3 and its downstream signaling, including PI3K/AKT, MEK/MAPK, JAK/STAT, and Src kinase, is believed to be necessary to conquer drug resistance and improve treatment efficiency. Until now, despite multiple anti-HER3 antibodies undergoing preclinical and clinical studies, none of the HER3-targeted therapies are licensed for utilization in clinical cancer treatment because of their safety and efficacy. Therefore, the development of HER3-targeted drugs possessing safety, tolerability, and sensitivity is crucial for clinical cancer treatment. This review summarizes the progress of the mechanism of HER3 in drug resistance, the HER3-targeted therapies that are conducted in preclinical and clinical trials, and some emerging molecules that could be used as future designed drugs for HER3, aiming to provide insights for future research and development of anticancer drugs targeting HER3.

Pancreatic cancer tumor microenvironment is a major therapeutic barrier and target

Pancreatic Ductal Adenocarcinoma (PDAC) is projected to become the 2nd leading cause of cancer-related deaths in the United States. Limitations in early detection and treatment barriers contribute to the lack of substantial success in the treatment of this challenging-to-treat malignancy. Desmoplasia is the hallmark of PDAC microenvironment that creates a physical and immunologic barrier. Stromal support cells and immunomodulatory cells face aberrant signaling by pancreatic cancer cells that shifts the complex balance of proper repair mechanisms into a state of dysregulation. The product of this dysregulation is the desmoplastic environment that encases the malignant cells leading to a dense, hypoxic environment that promotes further tumorigenesis, provides innate systemic resistance, and suppresses anti-tumor immune invasion. This desmoplastic environment combined with the immunoregulatory events that allow it to persist serve as the primary focus of this review. The physical barrier and immune counterbalance in the tumor microenvironment (TME) make PDAC an immunologically cold tumor. To convert PDAC into an immunologically hot tumor, tumor microenvironment could be considered alongside the tumor cells. We discuss the complex network of microenvironment molecular and cellular composition and explore how they can be targeted to overcome immuno-therapeutic challenges.

Recent advances in drug delivery and targeting for the treatment of pancreatic cancer

Despite significant treatment efforts, pancreatic ductal adenocarcinoma (PDAC), the deadliest solid tumor, is still incurable in the preclinical stages due to multifacet stroma, dense desmoplasia, and immune regression. Additionally, tumor heterogeneity and metabolic changes are linked to low grade clinical translational outcomes, which has prompted the investigation of the mechanisms underlying chemoresistance and the creation of effective treatment approaches by selectively targeting genetic pathways. Since targeting upstream molecules in first-line oncogenic signaling pathways typically has little clinical impact, downstream signaling pathways have instead been targeted in both preclinical and clinical studies. In this review, we discuss how the complexity of various tumor microenvironment (TME) components and the oncogenic signaling pathways that they are connected to actively contribute to the development and spread of PDAC, as well as the ways that recent therapeutic approaches have been targeted to restore it. We also illustrate how many endogenous stimuli-responsive linker-based nanocarriers have recently been developed for the specific targeting of distinct oncogenes and their downstream signaling cascades as well as their ongoing clinical trials. We also discuss the present challenges, prospects, and difficulties in the development of first-line oncogene-targeting medicines for the treatment of pancreatic cancer patients.

HER3: Toward the Prognostic Significance, Therapeutic Potential, Current Challenges, and Future Therapeutics in Different Types of Cancer

Human epidermal growth factor receptor 3 (HER3) is the only family member of the EGRF/HER family of receptor tyrosine kinases that lacks an active kinase domain (KD), which makes it an obligate binding partner with other receptors for its oncogenic role. When HER3 is activated in a ligand-dependent (NRG1/HRG) or independent manner, it can bind to other receptors (the most potent binding partner is HER2) to regulate many biological functions (growth, survival, nutrient sensing, metabolic regulation, etc.) through the PI3K-AKT-mTOR pathway. HER3 has been found to promote tumorigenesis, tumor growth, and drug resistance in different cancer types, especially breast and non-small cell lung cancer. Given its ubiquitous expression across different solid tumors and role in oncogenesis and drug resistance, there has been a long effort to target HER3. As HER3 cannot be targeted through its KD with small-molecule kinase inhibitors via the conventional method, pharmaceutical companies have used various other approaches, including blocking either the ligand-binding domain or extracellular domain for dimerization with other receptors. The development of treatment options with anti-HER3 monoclonal antibodies, bispecific antibodies, and different combination therapies showed limited clinical efficiency for various reasons. Recent reports showed that the extracellular domain of HER3 is not required for its binding with other receptors, which raises doubt about the efforts and applicability of the development of the HER3-antibodies for treatment. Whereas HER3-directed antibody-drug conjugates showed potentiality for treatment, these drugs are still under clinical trial. The currently understood model for dimerization-induced signaling remains incomplete due to the absence of the crystal structure of HER3 signaling complexes, and many lines of evidence suggest that HER family signaling involves more than the interaction of two members. This review article will significantly expand our knowledge of HER3 signaling and shed light on developing a new generation of drugs that have fewer side effects than the current treatment regimen for these patients.

Paclitaxel With or Without Cixutumumab as Second-Line Treatment of Metastatic Esophageal or Gastroesophageal Junction Cancer: A Randomized Phase II ECOG-ACRIN Trial

BACKGROUND

Patients with advanced esophageal cancer carry poor prognoses; limited data exist to guide second-line therapy in the metastatic setting. Paclitaxel has been used yet is associated with limited efficacy. There is preclinical evidence of synergy between paclitaxel and cixutumumab, a monoclonal antibody targeting insulin-like growth factor-1 receptor. We conducted a randomized phase II trial of paclitaxel (arm A) versus paclitaxel plus cixutumumab (arm B) in the second-line for patients with metastatic esophageal or gastroesophageal junction (GEJ) cancers.

METHODS

The primary endpoint was progression-free survival (PFS); 87 patients (43 in arm A, 44 in arm B) were treated.

RESULTS

Median PFS was 2.6 months in arm A [90% CL 1.8-3.5] and 2.3 months in arm B [90% 2.0-3.5], P = .86. Stable disease was observed in 29 (33%) patients. Objective response rates for Arms A and B were 12% [90% CI, 5-23%] and 14% [90% CI, 6-25%]. Median overall survival was 6.7 months [90% CL 4.9-9.5] in arm A and 7.2 months [90% CL 4.9-8.1] in arm B, P = 56.

CONCLUSION

The addition of cixutumumab to paclitaxel in second-line therapy of metastatic esophageal/GEJ cancer was well tolerated but did not improve clinical outcomes relative to standard of care (ClinicalTrials.gov Identifier: NCT01142388).

Identification of the shared gene signatures between pulmonary fibrosis and pulmonary hypertension using bioinformatics analysis

Pulmonary fibrosis (PF) and pulmonary hypertension (PH) have common pathophysiological features, such as the significant remodeling of pulmonary parenchyma and vascular wall. There is no effective specific drug in clinical treatment for these two diseases, resulting in a worse prognosis and higher mortality. This study aimed to screen the common key genes and immune characteristics of PF and PH by means of bioinformatics to find new common therapeutic targets. Expression profiles are downloaded from the Gene Expression Database. Weighted gene co-expression network analysis is used to identify the co-expression modules related to PF and PH. We used the ClueGO software to enrich and analyze the common genes in PF and PH and obtained the protein-protein interaction (PPI) network. Then, the differential genes were screened out in another cohort of PF and PH, and the shared genes were crossed. Finally, RT-PCR verification and immune infiltration analysis were performed on the intersection genes. In the result, the positive correlation module with the highest correlation between PF and PH was determined, and it was found that lymphocyte activation is a common feature of the pathophysiology of PF and PH. Eight common characteristic genes (ACTR2, COL5A2, COL6A3, CYSLTR1, IGF1, RSPO3, SCARNA17 and SEL1L) were gained. Immune infiltration showed that compared with the control group, resting CD4 memory T cells were upregulated in PF and PH. Combining the results of crossing characteristic genes in ImmPort database and RT-PCR, the important gene IGF1 was obtained. Knocking down IGF1 could significantly reduce the proliferation and apoptosis resistance in pulmonary microvascular endothelial cells, pulmonary smooth muscle cells, and fibroblasts induced by hypoxia, platelet-derived growth factor-BB (PDGF-BB), and transforming growth factor-β1 (TGF-β1), respectively. Our work identified the common biomarkers of PF and PH and provided a new candidate gene for the potential therapeutic targets of PF and PH in the future.

Therapeutic advances targeting tumor angiogenesis in pancreatic cancer: Current dilemmas and future directions

Pancreatic cancer (PC) is one of the most lethal malignancies, which is generally resistant to various treatments. Tumor angiogenesis is deemed to be a pivotal rate-determining step for tumor growth and metastasis. Therefore, anti-angiogenetic therapy is a rational strategy to treat various cancers. However, numerous clinical trials on anti-angiogenetic therapies for PC are overwhelmingly disappointing. The unique characteristics of tumor blood vessels in PC, which are desperately lacking and highly compressed by the dense desmoplastic stroma, are reconsidered to explore some optimized strategies. In this review, we mainly focus on its specific characteristics of tumor blood vessels, discuss the current dilemmas of anti-angiogenic therapy in PC and their underlying mechanisms. Furthermore, we point out the future directions, including remodeling the abnormal vasculature or even reshaping the whole tumor microenvironment in which they are embedded to improve tumor microcirculation, and then create therapeutic vulnerabilities to the current available therapeutic strategies.

Nab-Paclitaxel in the Treatment of Gastrointestinal Cancers-Improvements in Clinical Efficacy and Safety

Taxanes (paclitaxel and docetaxel) are one of the most useful classes of anticancer drugs. Taxanes are highly hydrophobic; therefore, these drugs must be dissolved in organic solvents (polysorbate or Cremophor EL), which contribute to their toxicities. To reduce this toxicity and to enhance their efficacy, novel formulations have been developed. Nanoparticle albumin-bound paclitaxel (nab-paclitaxel) is an albumin-stabilized, Cremophor-free, and water-soluble nanoparticle formulation of paclitaxel. Nab-paclitaxel has better solubility and less infusion-associated toxicity compared to solvent-based paclitaxel. Additionally, nab-paclitaxel can be given at higher doses and concentrations compared with solvent-based paclitaxel. Based on its superior clinical efficacy and safety profile, nab-paclitaxel received FDA approval for metastatic breast cancer (2008) and NSCLC (2011). Among gastrointestinal cancers, it is now approved in the USA for treating patients with metastatic adenocarcinoma of the pancreas as first-line therapy in combination with gemcitabine. Furthermore, several clinical trials have suggested the potential efficacy of nab-paclitaxel as a single agent or in combination with other agents for the treatment of metastatic esophageal, gastric, bowel, and biliary tract cancers. Nab-paclitaxel has been demonstrated to have greater overall response rates (ORR) with enhanced progression-free survival (PFS), overall survival (OS) and a superior safety profile with fewer adverse effects in patients with gastrointestinal tract cancers. This review summarizes the advantages associated with nab-paclitaxel-based regimens in terms of improving clinical efficacy and the safety profile in upper gastrointestinal cancer.

Understanding tumour endothelial cell heterogeneity and function from single-cell omics

Anti-angiogenic therapies (AATs) are used to treat different types of cancers. However, their success is limited owing to insufficient efficacy and resistance. Recently, single-cell omics studies of tumour endothelial cells (TECs) have provided new mechanistic insight. Here, we overview the heterogeneity of human TECs of all tumour types studied to date, at the single-cell level. Notably, most human tumour types contain varying numbers but only a small population of angiogenic TECs, the presumed targets of AATs, possibly contributing to the limited efficacy of and resistance to AATs. In general, TECs are heterogeneous within and across all tumour types, but comparing TEC phenotypes across tumours is currently challenging, owing to the lack of a uniform nomenclature for endothelial cells and consistent single-cell analysis protocols, urgently raising the need for a more consistent approach. Nonetheless, across most tumour types, universal TEC markers (ACKR1, PLVAP and IGFBP3) can be identified. Besides angiogenesis, biological processes such as immunomodulation and extracellular matrix organization are among the most commonly predicted enriched signatures of TECs across different tumour types. Although angiogenesis and extracellular matrix targets have been considered for AAT (without the hoped success), the immunomodulatory properties of TECs have not been fully considered as a novel anticancer therapeutic approach. Therefore, we also discuss progress, limitations, solutions and novel targets for AAT development.

Recent advances in targeted therapy for pancreatic adenocarcinoma

Pancreatic adenocarcinoma (PDAC) is a fatal disease with a 5-year survival rate of 8% and a median survival of 6 mo. In PDAC, several mutations in the genes are involved, with Kirsten rat sarcoma oncogene (90%), cyclin-dependent kinase inhibitor 2A (90%), and tumor suppressor 53 (75%–90%) being the most common. Mothers against decapentaplegic homolog 4 represents 50%. In addition, the self-preserving cancer stem cells, dense tumor microenvironment (fibrous accounting for 90% of the tumor volume), and suppressive and relatively depleted immune niche of PDAC are also constitutive and relevant elements of PDAC. Molecular targeted therapy is widely utilized and effective in several solid tumors. In PDAC, targeted therapy has been extensively evaluated; however, survival improvement of this aggressive disease using a targeted strategy has been minimal. There is currently only one United States Food and Drug Administration-approved targeted therapy for PDAC – erlotinib, but the absolute benefit of erlotinib in combination with gemcitabine is also minimal (2 wk). In this review, we summarize current targeted therapies and clinical trials targeting dysregulated signaling pathways and components of the PDAC oncogenic process, analyze possible reasons for the lack of positive results in clinical trials, and suggest ways to improve them. We also discuss emerging trends in targeted therapies for PDAC: combining targeted inhibitors of multiple pathways. The PubMed database and National Center for Biotechnology Information clinical trial website (www.clinicaltrials.gov) were queried to identify completed and published (PubMed) and ongoing (clinicaltrials.gov) clinical trials (from 2003-2022) using the keywords pancreatic cancer and targeted therapy. The PubMed database was also queried to search for information about the pathogenesis and molecular pathways of pancreatic cancer using the keywords pancreatic cancer and molecular pathways.

Clinical efficacy and safety of bispecific antibodies for the treatment of solid tumors: a systematic review and meta-analysis

INTRODUCTION

Immunotherapy is a promising and progressing treatment approach for cancer. Bispecific antibodies (BsAbs) are antibody constructs that can bind to two different epitopes. The dual-specificity of BsAbs improves their efficacy compared to monoclonal antibodies.

AREAS COVERED

Although BsAbs have achieved excellent therapeutic effects in hematologic cancers, no systematic review with meta-analysis evaluated their efficacy in solid tumors. In the present systematic review and meta-analysis, we aimed to establish the clinical efficacy and safety of BsAbs in solid tumors.

EXPERT OPINION

BsAbs are not associated with significantly better safety or efficacy outcomes than conventional therapies. BsAb was not associated with improvement in overall survival (OS), progression-free survival (PFS), objective response rate (ORR), and disease control rate (DCR). However, BsAb increased the rate of stable disease (SD) significantly. Also, BsAb substantially increased the OS and PFS and resulted in a higher frequency of DCR for uveal melanoma. Furthermore, the safety analysis showed no obvious difference in the rate of any adverse events (AEs), grade ≥3 AEs, serious AEs, and AEs leading to treatment discontinuation in the intervention group compared to controls. Further high-quality randomized controlled trials on BsAbs in solid tumors are highly recommended.

HER3 in cancer: from the bench to the bedside

The HER3 protein, that belongs to the ErbB/HER receptor tyrosine kinase (RTK) family, is expressed in several types of tumors. That fact, together with the role of HER3 in promoting cell proliferation, implicate that targeting HER3 may have therapeutic relevance. Furthermore, expression and activation of HER3 has been linked to resistance to drugs that target other HER receptors such as agents that act on EGFR or HER2. In addition, HER3 has been associated to resistance to some chemotherapeutic drugs. Because of those circumstances, efforts to develop and test agents targeting HER3 have been carried out. Two types of agents targeting HER3 have been developed. The most abundant are antibodies or engineered antibody derivatives that specifically recognize the extracellular region of HER3. In addition, the use of aptamers specifically interacting with HER3, vaccines or HER3-targeting siRNAs have also been developed. Here we discuss the state of the art of the preclinical and clinical development of drugs aimed at targeting HER3 with therapeutic purposes.

Meta-analysis of gemcitabine plus nab-paclitaxel combined with targeted agents in the treatment of metastatic pancreatic cancer

BACKGROUND

Gemcitabine plus nab-paclitaxel (GA) is a commonly used first-line treatment regimen for metastatic pancreatic cancer, and many studies will add a novel targeted agent to this regimen for improving patient survival rate. However, the clinical effectiveness of GA is the most controversial issue.

AIM

To compare the efficacy and safety of GA regimen with a targeted agent and GA regimen.

METHODS

Up to 1 December 2021, the eligible randomized controlled trials (RCTs) relating to GA and GA with a targeted agent were searched on PubMed, EMBASE and Cochrane Library for eligible data. We screened out appropriate studies for overall survival (OS), progression-free survival (PFS), objective response rate (ORR), and toxicity, which had been pooled and finally analyzed by using Stata version 15.1. In addition, we use Reference Citation Analysis (https://www.referencecitationanalysis.com/) to collect the latest related literature to improve the latest cutting-edge research results.

RESULTS

Seven RCTs involving 1544 patients (848 men and 696 women) were included. There were no significant differences between GA with a targeted agent and GA in PFS [hazard ratio (HR): 1.18 95% confidence interval (CI): 0.91-1.53], OS (HR: 1.12 95%CI: 0.99-1.27), and ORR (HR: 0.96 95%CI: 0.71-1.29). There was no notable difference in the two groups in grade 3/4 toxicity (fatigue, anemia, vomiting and neutropenia), whereas the incidence of grade 3/4 diarrhea considerably increased in GA with a targeted drug.

CONCLUSION

Adding a novel targeted agent to the GA regimen did not improve survival rate of patients with metastatic pancreatic cancer.

Antibody targeting of E3 ubiquitin ligases for receptor degradation

Most current therapies that target plasma membrane receptors function by antagonizing ligand binding or enzymatic activities. However, typical mammalian proteins comprise multiple domains that execute discrete but coordinated activities. Thus, inhibition of one domain often incompletely suppresses the function of a protein. Indeed, targeted protein degradation technologies, including proteolysis-targeting chimeras¹ (PROTACs), have highlighted clinically important advantages of target degradation over inhibition². However, the generation of heterobifunctional compounds binding to two targets with high affinity is complex, particularly when oral bioavailability is required³. Here we describe the development of proteolysis-targeting antibodies (PROTABs) that tether cell-surface E3 ubiquitin ligases to transmembrane proteins, resulting in target degradation both in vitro and in vivo. Focusing on zinc- and ring finger 3 (ZNRF3), a Wnt-responsive ligase, we show that this approach can enable colorectal cancer-specific degradation. Notably, by examining a matrix of additional cell-surface E3 ubiquitin ligases and transmembrane receptors, we demonstrate that this technology is amendable for ‘on-demand’ degradation. Furthermore, we offer insights on the ground rules governing target degradation by engineering optimized antibody formats. In summary, this work describes a strategy for the rapid development of potent, bioavailable and tissue-selective degraders of cell-surface proteins.

Membrane-bound E3 ubiquitin ligases RNF43 and ZNRF3 are overexpressed in colorectal cancer, and can be repurposed using proteolysis-targeting antibodies (PROTABs) to selectively degrade cell-surface receptors in tumours.

Beyond HER2: Targeting the ErbB receptor family in breast cancer

Targeting the HER2 oncogene represents one of the greatest advances in the treatment of breast cancer. HER2 is one member of the ERBB-receptor family, which includes EGFR (HER1), HER3 and HER4. In the presence or absence of underling genomic aberrations such as mutations or amplification events, intricate interactions between these proteins on the cell membrane lead to downstream signaling that encourages cancer growth and proliferation. In this Review, we contextualize efforts to pharmacologically target the ErbB receptor family beyond HER2, with a focus on EGFR and HER3. Preclinical and clinical efforts are synthesized. We discuss successes and failures of this approach to date, summarize lessons learned, and propose a way forward that invokes new therapeutic modalities such as antibody drug conjugates (ADCs), combination strategies, and patient selection through rational biomarkers.

Gemcitabine resistance of pancreatic cancer cells is mediated by IGF1R dependent upregulation of CD44 expression and isoform switching

Chemoresistance in pancreatic cancer cells may be caused by the expansion of inherently resistant cancer cells or by the adaptive plasticity of initially sensitive cancer cells. We investigated how CD44 isoforms switching contributed to gemcitabine resistance. Treating CD44 null/low single-cell clones with increasing amounts of gemcitabine caused an increase in expression of CD44 and development of gemcitabine resistant (GR) cells. Drug sensitivity, invasiveness, and EMT process was evaluated by MTT, Matrigel invasion assays, and western blots. Genetic knockdown and pharmacological inhibitors were used to examine the roles of CD44 and IGF1R in mediating gemcitabine resistance. CD44 promoter activity and its interactive EMT-related transcription factors were evaluated by luciferase reporter assay and chromatin immunoprecipitation assay. Kaplan-Meier curve was created by log-rank test to reveal the clinical relevance of CD44 and IGF1R expression in patients. We found silence of CD44 in GR cells partially restored E-cadherin expression, reduced ZEB1 expression, and increased drug sensitivity. The gemcitabine-induced CD44 expressing and isoform switching were associated with an increase in nuclear accumulation of phosphor-cJun, Ets1, and Egr1 and binding of these transcription factors to the CD44 promoter. Gemcitabine treatment induced phosphorylation of IGF1R and increased the expression of phosphor-cJun, Ets1, and Egr1 within 72 h. Stimulation or suppression of IGF1R signaling or its downstream target promoted or blocked CD44 promoter activity. Clinically, patients whose tumors expressed high levels of CD44/IGF1R showed a poor prognosis. This study suggests that IGF1R-dependent CD44 isoform switching confers pancreatic cancer cells to undergo an adaptive change in response to gemcitabine and provides the basis for improved targeted therapy of pancreatic cancer.

The HER family as therapeutic targets in colorectal cancer

The human epidermal growth factor receptor (HER, ErbB) family has four members, epidermal growth factor receptor (EGFR), HER2, HER3, and HER4. Although distinct in ligands and functions, all of the HER family members are receptor tyrosine kinases playing important roles in the pathogenesis of cancers. In the era of precision medicine, the HER family is one of the most important and successful cancer therapeutic targets, hallmarked by the approval of anti-EGFR therapies for the treatment of colorectal cancer and non-small cell lung cancer, and anti-HER2 therapies for the treatment of breast cancer and gastric cancer. This review briefly discusses how HER family members were discovered, their functions and roles in cancer, and most importantly, the developmental history and recent updates of therapies targeting HER family members, with colorectal cancer as a focus. We also discussed the patient selection and drug resistance to anti-EGFR therapies in the treatment of colorectal cancer.

High-valency Anti-CD99 Antibodies Toward the Treatment of T Cell Acute Lymphoblastic Leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive form of leukemia that currently requires intensive chemotherapy. While childhood T-ALL is associated with high cure rates, adult T-ALL is not, and both are associated with significant short- and long-term morbidities. Thus, less toxic and effective strategies to treat T-ALL are needed. CD99 is overexpressed on T-ALL blasts at diagnosis and at relapse. Although targeting CD99 with cytotoxic antibodies has been proposed, the molecular features required for their activity are undefined. We identified human antibodies that selectively bound to the extracellular domain of human CD99, and the most potent clone, 10A1, shared an epitope with a previously described cytotoxic IgM antibody. We engineered clone 10A1 in bivalent, trivalent, tetravalent, and dodecavalent formats. Increasing the antibody valency beyond two had no effects on binding to T-ALL cells. In contrast, a valency of ≥3 was required for cytotoxicity, suggesting a mechanism of action in which an antibody clusters ≥3 CD99 molecules to induce cytotoxicity. We developed a human IgG-based tetravalent version of 10A1 that exhibited cytotoxic activity to T-ALL cells but not to healthy peripheral blood cells. The crystal structure of the 10A1 Fab in complex with a CD99 fragment revealed that the antibody primarily recognizes a proline-rich motif (PRM) of CD99 in a manner reminiscent of SH3-PRM interactions. This work further validates CD99 as a promising therapeutic target in T-ALL and defines a pathway toward the development of a selective therapy against T-ALL.

Drugging IGF-1R in cancer: New insights and emerging opportunities

The insulin-like growth factor (IGF) axis plays important roles in cancer development and metastasis. The type 1 IGF receptor (IGF-1R) is a key member in the IGF axis and has long been recognized for its oncogenic role in multiple cancer lineages. Here we review the occurrence of IGF-1R aberrations and activation mechanisms in cancers, which justify the development of anti-IGF-1R therapies. We describe the therapeutic agents available for IGF-1R inhibition, with focuses on the recent or ongoing pre-clinical and clinical studies. These include antisense oligonucleotide, tyrosine kinase inhibitors and monoclonal antibodies which may be conjugated with cytotoxic drug. Remarkably, simultaneous targeting of IGF-1R and several other oncogenic vulnerabilities has shown early promise, highlighting the potential benefits of combination therapy. Further, we discuss the challenges in targeting IGF-1R so far and new concepts to improve therapeutic efficacy such as blockage of the nuclear translocation of IGF-1R.

Targeting the IGF-1R in prostate and colorectal cancer: reasons behind trial failure and future directions

IGF-1Rs enact a significant part in cancer growth and its progress. IGF-1R inhibitors were encouraged in the early trials, but the patients did not benefit due to the unavailability of predictive biomarkers and IGF-1R system complexity. However, the linkage between IGF-1R and cancer was reported three decades ago. This review will shed light on the IGF-1R system, targeting IGF-1R through monoclonal antibodies, reasons behind IGF-1R trial failure and future directions. This study presented that targeting IGF-1R through monoclonal antibodies is still effective in cancer treatment, and there is a need to look for future directions. Cancer patients may benefit from using mAbs that target existing and new cancer targets, evidenced by promising results. It is also essential that the academician, trial experts and pharmaceutical companies play their role in finding a treatment for this deadly disease.

Engineered Bifunctional Proteins for Targeted Cancer Therapy: Prospects and Challenges

Bifunctional proteins (BFPs) are a class of therapeutic agents produced through genetic engineering and protein engineering, and are increasingly used to treat various human diseases, including cancer. These proteins usually have two or more biological functions-specifically recognizing different molecular targets to regulate the related signaling pathways, or mediating effector molecules/cells to kill tumor cells. Unlike conventional small-molecule or single-target drugs, BFPs possess stronger biological activity but lower systemic toxicity. Hence, BFPs are considered to offer many benefits for the treatment of heterogeneous tumors. In this review, the authors briefly describe the unique structural feature of BFP molecules and innovatively divide them into bispecific antibodies, cytokine-based BFPs (immunocytokines), and protein toxin-based BFPs (immunotoxins) according to their mode of action. In addition, the latest advances in the development of BFPs are discussed and the potential limitations or problems in clinical applications are outlined. Taken together, future studies need to be centered on understanding the characteristics of BFPs for optimizing and designing more effective such drugs.

Targeting obesity-related dysfunction in hormonally driven cancers

Obesity is a risk factor for at least 13 different types of cancer, many of which are hormonally driven, and is associated with increased cancer incidence and morbidity. Adult obesity rates are steadily increasing and a subsequent increase in cancer burden is anticipated. Obesity-related dysfunction can contribute to cancer pathogenesis and treatment resistance through various mechanisms, including those mediated by insulin, leptin, adipokine, and aromatase signalling pathways, particularly in women. Furthermore, adiposity-related changes can influence tumour vascularity and inflammation in the tumour microenvironment, which can support tumour development and growth. Trials investigating non-pharmacological approaches to target the mechanisms driving obesity-mediated cancer pathogenesis are emerging and are necessary to better appreciate the interplay between malignancy, adiposity, diet and exercise. Diet, exercise and bariatric surgery are potential strategies to reverse the cancer-promoting effects of obesity; trials of these interventions should be conducted in a scientifically rigorous manner with dose escalation and appropriate selection of tumour phenotypes and have cancer-related clinical and mechanistic endpoints. We are only beginning to understand the mechanisms by which obesity effects cell signalling and systemic factors that contribute to oncogenesis. As the rates of obesity and cancer increase, we must promote the development of non-pharmacological lifestyle trials for the treatment and prevention of malignancy.

Targeting Growth Factor Signaling Pathways in Pancreatic Cancer: Towards Inhibiting Chemoresistance

Pancreatic cancer is one of the most deadly cancers, ranking amongst the top leading cause of cancer related deaths in developed countries. Features such as dense stroma microenvironment, abnormal signaling pathways, and genetic heterogeneity of the tumors contribute to its chemoresistant characteristics. Amongst these features, growth factors have been observed to play crucial roles in cancer cell survival, progression, and chemoresistance. Here we review the role of the individual growth factors in pancreatic cancer chemoresistance. Importantly, the interplay between the tumor microenvironment and chemoresistance is explored in the context of pivotal role played by growth factors. We further describe current and future potential therapeutic targeting of these factors.

Emerging antibody therapies for pancreatic adenocarcinoma: a review of recent phase 2 trials

Introduction: Pancreatic adenocarcinoma is now the third-leading cause of cancer-related deaths in the US which can be attributed to rising incidence, diagnosis at advanced stages and early development of metastasis. Systemic therapy remains palliative with early development of resistance possibly related to the constitutive activation of 'undruggable' KRAS, immunosuppressive microenvironment, and intense desmoplasia. The advancements in molecular biology has led to the development and investigation of targeted and immune therapeutics.Areas covered: This study provides a comprehensive review of the literature to further the understanding of molecular targets with their respective antibody-based therapies in clinical development in pancreatic cancer. PubMed was systematically searched for English-language articles discussing antibody-based therapies under phase 2 clinical trial investigation in pancreatic adenocarcinoma.Expert opinion: PDAC remains highly resistant to chemotherapy with no significant improvement in survival for patients with advanced or metastatic cancer. Unfortunately, the majority of the antibody-based targeted and immune therapeutics have failed to meet their primary efficacy endpoints in early phase trials. However, there are a few promising antibody-based drugs with intriguing preliminary data that merit further investigation, while many more continue to be developed and investigated preclinically, and in early phase trials.

Neisseria gonorrhoeae Multivalent Maxibody with a Broad Spectrum of Strain Specificity and Sensitivity for Gonorrhea Diagnosis

Gonorrhea is one of the most common, but still hidden and insidious, sexually transmitted diseases caused by Neisseria gonorrhoeae (gonococci). However, the diagnosis and treatment of gonorrhea are hampered by antigenic variability among gonococci, the lack of acquired immunity, and antimicrobial resistance. Further, strains resistant to cephalosporins, including ceftriaxone, the last line of defense, represent a growing threat, which prompted us to develop gonococci-specific diagnostic antibodies with broad-spectrum binding to gonococci strains to generate gonorrhea-detecting reagents. This study reports the identification of gonococci antibodies via bio-panning on gonococci cells using scFv-phage libraries. Reformatting the lead scFv-phage Clones 1 and 4 to a multivalent scFv1-Fc-scFv4 maxibody increased the sensitivity by up to 20-fold compared to the single scFv-Fc (maxibody) alone. Moreover, the multivalent maxibody showed broader cross-reactivity with clinical isolates and the ceftriaxone antibiotic-resistant World Health Organization (WHO) reference strain L. In contrast, the selected antibodies in the scFv-phage, maxibody, and multivalent maxibody did not bind to N. sicca, N. meningitides, and N. lactamica, suggesting the clinical and pharmaceutical diagnostic value of these selected antibodies for gonorrheal infections. The present study illustrates the advantages and potential application of multivalent maxibodies to develop rapid and sensitive diagnostic reagents for infectious diseases and cancer.

A novel tumor inhibitory hybridoma monoclonal antibody with dual specificity for HER3 and HER2

BACKGROUND

The human epidermal growth factor receptor (HER/ErbB) family-targeted therapies result in a significant improvement in cancer immunotherapy. Monoclonal antibodies (MAb) against HER2 demonstrated a survival benefit for patients; however, drug resistance unavoidably occurs due to the overexpression of HER3, which leads to treatment failure. Effective inhibition of HER3 besides HER2 is thought to be required to overcome resistance and enhance therapeutic efficacy.

OBJECTIVE

The present study describes the production and characterization of a novel MAb, designated 1G5D2, which acts as a natural bispecific antibody targeting extracellular domains (ECD) of both HER2 and HER3.

METHODS

In this study, 1G5D2 was produced by hybridoma technology against HER3-ECD, and its structural and functional characteristics were studied by various methodologies, including enzyme linked-immunosorbent assays, flow cytometry, immunoblotting, cell signaling, and cell proliferation assays.

RESULTS

1G5D2 specifically binds to both HER2 (subdomain III + IV) and HER3 (subdomain I + II) expressed on tumor cells, and these receptors compete with each other for binding to this MAb. Competition flow cytometry experiments demonstrated that 1G5D2 does not compete with heregulin and recognizes an epitope out of HER3 ligand-binding site. Evaluation of 1G5D2 inhibitory effects in tumor cell lines co-expressing HER2 and HER3 showed that 1G5D2 synergizes with trastuzumab to inhibit both PI3K/AKT and MAPK/ERK pathways and potently downregulates the proliferation of these tumor cells more efficiently than each MAb alone.

CONCLUSION

1G5D2 is the first reported hybridoma antibody, which acts as a natural HER2/HER3 bispecific antibody. It might potentially be a suitable therapeutic candidate for HER2/HER3 overexpressing cancer types.

Thirty Years of HER3: From Basic Biology to Therapeutic Interventions

HER3 is a pseudokinase member of the EGFR family having a role in both tumor progression and drug resistance. Although HER3 was discovered more than 30 years ago, no therapeutic interventions have reached clinical approval to date. Because the evidence of the importance of HER3 is accumulating, increased amounts of preclinical and clinical trials with HER3-targeting agents are emerging. In this review article, we discuss the most recent HER3 biology in tumorigenic events and drug resistance and provide an overview of the current and emerging strategies to target HER3.

Two decades of research toward the treatment of locally advanced and metastatic pancreatic cancer: Remarkable effort and limited gain

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy that is diagnosed at the locally advanced or metastatic stage in approximately 80% of cases. Relative to other tumor types, progress in the treatment of this disease has been painfully slow. While agents targeting DNA repair have proven successful in a subset of patients, the majority of PDACs do not exhibit validated molecular targets. Hence, conventional chemotherapy remains at the forefront of therapy for this disease. In this review, we study two decades of efforts to improve upon the gemcitabine backbone - 67 phase II and III trials enrolling 16,446 patients - that culminated in the approvals of gemcitabine/nab-paclitaxel (Gem/NabP) and FOLFIRINOX. Today, these remain gold standards for the first-line treatment of locally advanced unresectable and metastatic PDAC, while ongoing efforts focus on improving upon the Gem/NabP backbone. Because real world data often do not reflect the data of randomized controlled trials (RCTs), we also summarize the retrospective evidence comparing the efficacy of Gem/NabP and FOLFIRINOX in the first-line setting - 29 studies reporting a median overall survival of 10.7 and 9.1 months for FOLFIRINOX and Gem/NabP, respectively. These values are surprisingly comparable to those reported by the pivotal RCTs at 11.1 and 8.5 months. Finally, there is a paucity of RCT data regarding the efficacy of second-line therapy. Hence, we conclude this review by summarizing the data that ultimately demonstrate a small but significant survival benefit of second-line therapy with Gem/NabP or FOLFIRINOX. Collectively, these studies describe the long journey, the steady effort, and the myriad lessons to be learned from 20 years of PDAC trials to inform strategies for success in clinical trials moving forward.

Targeting Leukemia-Initiating Cells in Acute Lymphoblastic Leukemia

The concept that different leukemias are developmentally distinct and, like in normal hematopoiesis, generated by restricted populations of cells named leukemia-initiating cells (LIC), is becoming more established. These cancer stem-like cells have been assumed to have unique properties, including the capability of self-renewing and giving rise to "differentiated" or non-LICs that make up the whole tumor. Cell populations enriched with LIC activity have been characterized in different hematopoietic malignancies, including human acute lymphoblastic leukemia (ALL). Related studies have also demonstrated that LICs are functionally distinct from bulk cells and modulated by distinct molecular signaling pathways and epigenetic mechanisms. Here we review several biological and clinical aspects related to LICs in ALL, including (i) immunophenotypic characterization of LIC-enriched subsets in human and mouse models of ALL, (ii) emerging therapeutics against regulatory signaling pathways involved in LIC progression and maintenance in T- and B-cell leukemias, (iii) novel epigenetic and age-related mechanisms of LIC propagation, and (iv) ongoing efforts in immunotherapy to eradicate LIC-enriched cell subsets in relapsed and refractory ALL cases. Current conventional treatments do not efficiently eliminate LICs. Therefore, innovative therapeutics that exclusively target LICs hold great promise for developing an effective cure for ALL.

TP53 Mutational Status-Based Genomic Signature for Prognosis and Predicting Therapeutic Response in Pancreatic Cancer

TP53 mutation is a critical driver mutation that affects the carcinogenesis and prognosis of patients with pancreatic cancer (PC). Currently, there is no driver mutation-derived signature based on TP53 mutational status for prognosis and predicting therapeutic response in PC. In the present study, we characterized the TP53 mutational phenotypes in multiple patient cohorts and developed a prognostic TP53-associated signature based on differentially expressed genes between PC samples with mutated TP53 and wild-type TP53. Comprehensive investigations were carried out in prognostic stratification, genetic variation, immune cell infiltration, and efficacy prediction of chemotherapy and targeted therapy. We found that TP53 mutation commonly occurred as a survival-related driver mutation in PC. In total, 1,154 differentially expressed genes were found between two distinct TP53 mutational phenotypes. A five-gene TP53-associated signature was constructed in The Cancer Genome Atlas (TCGA) cohort by least absolute shrinkage and selection operator (LASSO)-Cox analysis and proven to be a robust prognostic predictor, which performed well in three independent Gene Expression Omnibus (GEO) validating cohorts. Remarkably, patients in the low-risk group were characterized with decreased tumor mutation burden and activity of immunity, with favorable prognosis. Higher fractions of macrophages M0 and impaired CD8 + T cells were observed in patients in the high-risk group, suggesting immunosuppression with poor survival. Patients in the high-risk group also demonstrated enhanced response to specific chemotherapeutic agents, including gemcitabine and paclitaxel. Several targeted inhibitors, like histamine receptor inhibitor, were screened out as promising drugs for PC treatment. Collectively, the TP53-associated signature is a novel prognostic biomarker and predictive indicator of PC. The signature could contribute to optimizing prognostic stratification and guide effective PC treatments.

Pancreatic cancer stroma: an update on therapeutic targeting strategies

Pancreatic ductal adenocarcinoma (PDAC) is a leading cause of cancer-related mortality in the Western world with limited therapeutic options and dismal long-term survival. The neoplastic epithelium exists within a dense stroma, which is recognized as a critical mediator of disease progression through direct effects on cancer cells and indirect effects on the tumour immune microenvironment. The three dominant entities in the PDAC stroma are extracellular matrix (ECM), vasculature and cancer-associated fibroblasts (CAFs). The ECM can function as a barrier to effective drug delivery to PDAC cancer cells, and a multitude of strategies to target the ECM have been attempted in the past decade. The tumour vasculature is a complex system and, although multiple anti-angiogenesis agents have already failed late-stage clinical trials in PDAC, other vasculature-targeting approaches aimed at vessel normalization and tumour immunosensitization have shown promise in preclinical models. Lastly, PDAC CAFs participate in active cross-talk with cancer cells within the tumour microenvironment. The existence of intratumoural CAF heterogeneity represents a paradigm shift in PDAC CAF biology, with myofibroblastic and inflammatory CAF subtypes that likely make distinct contributions to PDAC progression. In this Review, we discuss our current understanding of the three principal constituents of PDAC stroma, their effect on the prevalent immune landscape and promising therapeutic targets within this compartment.

Targeting the IGF-Axis for Cancer Therapy: Development and Validation of an IGF-Trap as a Potential Drug

The insulin-like growth factor (IGF)-axis was implicated in cancer progression and identified as a clinically important therapeutic target. Several IGF-I receptor (IGF-IR) targeting drugs including humanized monoclonal antibodies have advanced to phase II/III clinical trials, but to date, have not progressed to clinical use, due, at least in part, to interference with insulin receptor signaling and compensatory signaling by the insulin receptor (IR) isoform A that can bind IGF-II and initiate mitogenic signaling. Here we briefly review the current state of IGF-targeting biologicals, discuss some factors that may be responsible for their poor performance in the clinic and outline the stepwise bioengineering and validation of an IGF-Trap—a novel anti-cancer therapeutic that could bypass these limitations. The IGF-Trap is a heterotetramer, consisting of the entire extracellular domain of the IGF-IR fused to the Fc portion of human IgG₁. It binds human IGF-I and IGF-II with a three-log higher affinity than insulin and could inhibit IGF-IR driven cellular functions such as survival, proliferation and invasion in multiple carcinoma cell models in vitro. In vivo, the IGF-Trap has favorable pharmacokinetic properties and could markedly reduce metastatic outgrowth of colon and lung carcinoma cells in the liver, outperforming IGF-IR and ligand-binding monoclonal antibodies. Moreover, IGF-Trap dose-response profiles correlate with their bio-availability profiles, as measured by the IGF kinase receptor-activation (KIRA) assay, providing a novel, surrogate biomarker for drug efficacy. Our studies identify the IGF-Trap as a potent, safe, anti-cancer therapeutic that could overcome some of the obstacles encountered by IGF-targeting biologicals that have already been evaluated in clinical settings.

TRIM21 and PHLDA3 negatively regulate the crosstalk between the PI3K/AKT pathway and PPP metabolism

PI3K/AKT signaling is known to regulate cancer metabolism, but whether metabolic feedback regulates the PI3K/AKT pathway is unclear. Here, we demonstrate the important reciprocal crosstalk between the PI3K/AKT signal and pentose phosphate pathway (PPP) branching metabolic pathways. PI3K/AKT activation stabilizes G6PD, the rate-limiting enzyme of the PPP, by inhibiting the newly identified E3 ligase TIRM21 and promotes the PPP. PPP metabolites, in turn, reinforce AKT activation and further promote cancer metabolic reprogramming by blocking the expression of the AKT inhibitor PHLDA3. Knockout of TRIM21 or PHLDA3 promotes crosstalk and cell proliferation. Importantly, PTEN null human cancer cells and in vivo murine models are sensitive to anti-PPP treatments, suggesting the importance of the PPP in maintaining AKT activation even in the presence of a constitutively activated PI3K pathway. Our study suggests that blockade of this reciprocal crosstalk mechanism may have a therapeutic benefit for cancers with PTEN loss or PI3K/AKT activation.