A Randomized, Open-Label Phase 2 Study of the CXCR4 Inhibitor LY2510924 in Combination with Sunitinib Versus Sunitinib Alone in Patients with Metastatic Renal Cell Carcinoma (RCC)

Targeting CXCR4/CXCL12 axis via [177Lu]Lu-DOTAGA.(SA.FAPi)2 with CXCR4 antagonist in triple-negative breast cancer

PURPOSE

Radiopharmaceutical therapies targeting fibroblast activation protein (FAP) have shown promising efficacy against many tumor types. But radiopharmaceuticals alone in most cases are insufficient to completely eradicate tumor cells, which can partially be attributed to the protective interplay between tumor cells and cancer-associated fibroblasts (CAFs). The C-X-C chemokine receptor type 4/C-X-C motif chemokine 12 (CXCR4/CXCL12) interaction plays an important role in orchestrating tumor cells and CAFs. We hereby investigated the feasibility and efficacy of [177Lu]Lu-DOTAGA.(SA.FAPi)2, a FAP-targeting radiopharmaceutical, in combination with AMD3100, a CXCR4 antagonist, in a preclinical murine model of triple-negative breast cancer (TNBC).

METHODS

Public database was first interrogated to reveal the correlation between CAFs' scores and the prognosis of TNBC patients, as well as the expression levels of FAP and CXCR4 in normal tissues and tumors. In vitro therapeutic efficacy regarding cell proliferation, migration, and colony formation was assessed in BALB/3T3 fibroblasts and 4T1 murine breast cancer cells. In vivo therapeutic efficacy was longitudinally monitored using serial 18F-FDG, [18F]AlF-NOTA-FAPI-04, and [68Ga]Ga-DOTA-Pentixafor PET/CT scans and validated using tumor sections through immunohistochemical staining of Ki-67, α-SMA, CXCR4, and CXCL12. Intratumoral abundance of myeloid-derived suppressive cells (MDSCs) was analyzed using flow cytometry in accordance with the PET/CT schedules. Treatment toxicity was evaluated by examining major organs including heart, lung, liver, kidney, and spleen.

RESULTS

CAFs' scores negatively correlated with the survival of TNBC patients (p < 0.05). The expression of CXCR4 and FAP was both significantly higher in tumors than in normal tissues. The combination of [177Lu]Lu-DOTAGA.(SA.FAPi)2 and AMD3100 significantly suppressed cell proliferation, migration, and colony formation in cell culture, and exhibited synergistic effects in 4T1 tumor models along with a decreased number of MDSCs. PET/CT imaging revealed lowest tumor accumulation of 18F-FDG and [18F]AlF-NOTA-FAPI-04 on day 13 and day 14 after treatment started, both of which gradually increased at later time points. A similar trend was observed in the IHC staining of Ki-67, α-SMA, and CXCL12.

CONCLUSION

The combination of [177Lu]Lu-DOTAGA.(SA.FAPi)2 and AMD3100 is a feasible treatment against TNBC with minimal toxicity in main organs.

Chemokine systems in oncology: From microenvironment modulation to nanocarrier innovations

Over the past few decades, significant strides have been made in understanding the pivotal roles that chemokine networks play in tumor biology. These networks, comprising chemokines and their receptors, wield substantial influence over cancer immune regulation and therapeutic outcomes. As a result, targeting these chemokine systems has emerged as a promising avenue for cancer immunotherapy. However, therapies targeting chemokines face significant challenges in solid tumor treatment, due to the complex and fragile of the chemokine networks. A nuanced comprehension of the complicacy and functions of chemokine networks, and their impact on the tumor microenvironment, is essential for optimizing their therapeutic utility in oncology. This review elucidates the ways in which chemokine networks interact with cancer immunity and tumorigenesis. We particularly elaborate on recent innovations in manipulating these networks for cancer treatment. The review also highlights future challenges and explores potential biomaterial strategies for clinical applications.

Small-molecule agents for cancer immunotherapy

Cancer immunotherapy, exemplified by the remarkable clinical benefits of the immune checkpoint blockade and chimeric antigen receptor T-cell therapy, is revolutionizing cancer therapy. They induce long-term tumor regression and overall survival benefit in many types of cancer. With the advances in our knowledge about the tumor immune microenvironment, remarkable progress has been made in the development of small-molecule drugs for immunotherapy. Small molecules targeting PRR-associated pathways, immune checkpoints, oncogenic signaling, metabolic pathways, cytokine/chemokine signaling, and immune-related kinases have been extensively investigated. Monotherapy of small-molecule immunotherapeutic drugs and their combinations with other antitumor modalities are under active clinical investigations to overcome immune tolerance and circumvent immune checkpoint inhibitor resistance. Here, we review the latest development of small-molecule agents for cancer immunotherapy by targeting defined pathways and highlighting their progress in recent clinical investigations.

Biological and mutational analyses of CXCR4-antagonist interactions and design of new antagonistic analogs

The chemokine receptor CXCR4 has become an attractive therapeutic target for HIV-1 infection, hematopoietic stem cell mobilization, and cancer metastasis. A wide variety of synthetic antagonists of CXCR4 have been developed and studied for a growing list of clinical applications. To compare the biological effects of different antagonists on CXCR4 functions and their common and/or distinctive molecular interactions with the receptor, we conducted head-to-head comparative cell-based biological and mutational analyses of the interactions with CXCR4 of eleven reported antagonists, including HC4319, DV3, DV1, DV1 dimer, V1, vMIP-II, CVX15, LY2510924, IT1t, AMD3100, and AMD11070 that were representative of different structural classes of D-peptides, L-peptide, natural chemokine, cyclic peptides, and small molecules. The results were rationalized by molecular modeling of CXCR4-antagonist interactions from which the common as well as different receptor binding sites of these antagonists were derived, revealing a number of important residues such as W94, D97, H113, D171, D262, and E288, mostly of negative charge. To further examine this finding, we designed and synthesized new antagonistic analogs by adding positively charged residues Arg to a D-peptide template to enhance the postulated charge-charge interactions. The newly designed analogs displayed significantly increased binding to CXCR4, which supports the notion that negatively charged residues of CXCR4 can engage in interactions with moieties of positive charge of the antagonistic ligands. The results from these mutational, modeling and new analog design studies shed new insight into the molecular mechanisms of different types of antagonists in recognizing CXCR4 and guide the development of new therapeutic agents.

Small-molecule inhibitors of kinases in breast cancer therapy: recent advances, opportunities, and challenges

Breast cancer is the most common malignancy in women worldwide and despite significant advancements in detection, treatment, and management of cancer, it is still the leading cause of malignancy related deaths in women. Understanding the fundamental biology of breast cancer and creating fresh diagnostic and therapeutic strategies have gained renewed focus in recent studies. In the onset and spread of breast cancer, a group of enzymes known as kinases are extremely important. Small-molecule kinase inhibitors have become a promising class of medications for the treatment of breast cancer owing to their capacity to specifically target kinases involved in the growth and progression of cancer. The creation of targeted treatments that block these kinases and the signalling pathways that they activate has completely changed how breast cancer is treated. Many of these targeted treatments have been approved for the treatment of breast cancer as clinical trials have demonstrated their great efficacy. CDK4/6 inhibitors, like palbociclib, abemaciclib, and ribociclib, EGFR inhibitors such as gefitinib and erlotinib and HER2-targeting small-molecule kinases like neratinib and tucatinib are some examples that have shown potential in treating breast cancer. Yet, there are still difficulties in the development of targeted medicines for breast cancer, such as figuring out which patient subgroups may benefit from these therapies and dealing with drug resistance problems. Notwithstanding these difficulties, kinase-targeted treatments for breast cancer still have a lot of potential. The development of tailored medicines will continue to be fuelled by the identification of novel targets and biomarkers for breast cancer as a result of advancements in genomic and proteomic technology.

First-line therapy for adults with advanced renal cell carcinoma: a systematic review and network meta-analysis

BACKGROUND

Since the approval of tyrosine kinase inhibitors, angiogenesis inhibitors and immune checkpoint inhibitors, the treatment landscape for advanced renal cell carcinoma (RCC) has changed fundamentally. Today, combined therapies from different drug categories have a firm place in a complex first-line therapy. Due to the large number of drugs available, it is necessary to identify the most effective therapies, whilst considering their side effects and impact on quality of life (QoL).

OBJECTIVES

To evaluate and compare the benefits and harms of first-line therapies for adults with advanced RCC, and to produce a clinically relevant ranking of therapies. Secondary objectives were to maintain the currency of the evidence by conducting continuous update searches, using a living systematic review approach, and to incorporate data from clinical study reports (CSRs).

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, conference proceedings and relevant trial registries up until 9 February 2022. We searched several data platforms to identify CSRs.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) evaluating at least one targeted therapy or immunotherapy for first-line treatment of adults with advanced RCC. We excluded trials evaluating only interleukin-2 versus interferon-alpha as well as trials with an adjuvant treatment setting. We also excluded trials with adults who received prior systemic anticancer therapy if more than 10% of participants were previously treated, or if data for untreated participants were not separately extractable.

DATA COLLECTION AND ANALYSIS

All necessary review steps (i.e. screening and study selection, data extraction, risk of bias and certainty assessments) were conducted independently by at least two review authors. Our outcomes were overall survival (OS), QoL, serious adverse events (SAEs), progression-free survival (PFS), adverse events (AEs), the number of participants who discontinued study treatment due to an AE, and the time to initiation of first subsequent therapy. Where possible, analyses were conducted for the different risk groups (favourable, intermediate, poor) according to the International Metastatic Renal-Cell Carcinoma Database Consortium Score (IMDC) or the Memorial Sloan Kettering Cancer Center (MSKCC) criteria. Our main comparator was sunitinib (SUN). A hazard ratio (HR) or risk ratio (RR) lower than 1.0 is in favour of the experimental arm.

MAIN RESULTS

We included 36 RCTs and 15,177 participants (11,061 males and 4116 females). Risk of bias was predominantly judged as being 'high' or 'some concerns' across most trials and outcomes. This was mainly due to a lack of information about the randomisation process, the blinding of outcome assessors, and methods for outcome measurements and analyses. Additionally, study protocols and statistical analysis plans were rarely available. Here we present the results for our primary outcomes OS, QoL, and SAEs, and for all risk groups combined for contemporary treatments: pembrolizumab + axitinib (PEM+AXI), avelumab + axitinib (AVE+AXI), nivolumab + cabozantinib (NIV+CAB), lenvatinib + pembrolizumab (LEN+PEM), nivolumab + ipilimumab (NIV+IPI), CAB, and pazopanib (PAZ). Results per risk group and results for our secondary outcomes are reported in the summary of findings tables and in the full text of this review. The evidence on other treatments and comparisons can also be found in the full text. Overall survival (OS) Across risk groups, PEM+AXI (HR 0.73, 95% confidence interval (CI) 0.50 to 1.07, moderate certainty) and NIV+IPI (HR 0.69, 95% CI 0.69 to 1.00, moderate certainty) probably improve OS, compared to SUN, respectively. LEN+PEM may improve OS (HR 0.66, 95% CI 0.42 to 1.03, low certainty), compared to SUN. There is probably little or no difference in OS between PAZ and SUN (HR 0.91, 95% CI 0.64 to 1.32, moderate certainty), and we are uncertain whether CAB improves OS when compared to SUN (HR 0.84, 95% CI 0.43 to 1.64, very low certainty). The median survival is 28 months when treated with SUN. Survival may improve to 43 months with LEN+PEM, and probably improves to: 41 months with NIV+IPI, 39 months with PEM+AXI, and 31 months with PAZ. We are uncertain whether survival improves to 34 months with CAB. Comparison data were not available for AVE+AXI and NIV+CAB. Quality of life (QoL) One RCT measured QoL using FACIT-F (score range 0 to 52; higher scores mean better QoL) and reported that the mean post-score was 9.00 points higher (9.86 lower to 27.86 higher, very low certainty) with PAZ than with SUN. Comparison data were not available for PEM+AXI, AVE+AXI, NIV+CAB, LEN+PEM, NIV+IPI, and CAB. Serious adverse events (SAEs) Across risk groups, PEM+AXI probably increases slightly the risk for SAEs (RR 1.29, 95% CI 0.90 to 1.85, moderate certainty) compared to SUN. LEN+PEM (RR 1.52, 95% CI 1.06 to 2.19, moderate certainty) and NIV+IPI (RR 1.40, 95% CI 1.00 to 1.97, moderate certainty) probably increase the risk for SAEs, compared to SUN, respectively. There is probably little or no difference in the risk for SAEs between PAZ and SUN (RR 0.99, 95% CI 0.75 to 1.31, moderate certainty). We are uncertain whether CAB reduces or increases the risk for SAEs (RR 0.92, 95% CI 0.60 to 1.43, very low certainty) when compared to SUN. People have a mean risk of 40% for experiencing SAEs when treated with SUN. The risk increases probably to: 61% with LEN+PEM, 57% with NIV+IPI, and 52% with PEM+AXI. It probably remains at 40% with PAZ. We are uncertain whether the risk reduces to 37% with CAB. Comparison data were not available for AVE+AXI and NIV+CAB.

AUTHORS' CONCLUSIONS

Findings concerning the main treatments of interest comes from direct evidence of one trial only, thus results should be interpreted with caution. More trials are needed where these interventions and combinations are compared head-to-head, rather than just to SUN. Moreover, assessing the effect of immunotherapies and targeted therapies on different subgroups is essential and studies should focus on assessing and reporting relevant subgroup data. The evidence in this review mostly applies to advanced clear cell RCC.

Differential Expression and Clinical Relevance of C-X-C Motif Chemokine Receptor 4 (CXCR4) in Renal Cell Carcinomas, Benign Renal Tumors, and Metastases

C-X-C Motif Chemokine Receptor 4 (CXCR4) is part of the human chemokine system and involved in progression and metastasis in renal cell carcinoma (RCC). However, the role of CXCR4 protein expression in RCC remains controversial. In particular, data regarding the subcellular distribution of CXCR4 in RCC and RCC metastasis as well as CXCR4 expression in renal tumors of variant histology are limited. The aim of the present study was the evaluation of the differential CXCR4 expression in RCC primary tumor and metastatic tissue as well as in variant renal histologies. In addition, the prognostic capacity of CXCR4 expression in organ-confined clear cell RCC (ccRCC) was evaluated. Three independent renal tumor cohorts (primary ccRCC cohort n1 = 64; cohort of various histological entities n2 = 146; metastatic RCC tissue cohort n3 = 92) were evaluated using tissue microarrays (TMA). After immunohistochemical staining for CXCR4, nuclear and cytoplasmic expression patterns were evaluated. CXCR4 expression was correlated with validated pathologic prognosticators, clinical data, and overall and cancer-specific survival. Positive cytoplasmic staining was observed in 98% of the benign and 38.9% of the malignant samples. Nuclear staining was positive for 94.1% of the benign samples and 83% of the malignant samples. The median cytoplasmic expression score was found to be higher in benign tissue than in ccRCC (130.00 vs. 0.00); median nuclear expression score analysis indicated the opposite (56.0 vs. 71.0). Within malignant subtypes, the highest expression score was seen in papillary renal cell carcinomas (cytoplasmic: 117.50, nuclear: 41.50). Within benign renal tumors, high cytoplasmic and nuclear CXCR4 expression scores were seen for oncocytomas (cytoplasmic: 100.00, nuclear: 31.00). Expression scores in RCC metastasis ranked between benign renal tissue and ccRCC in cytoplasmic and nuclear expression. Cytoplasmic CXCR4 expression was identified as a prognostic factor for OS and CSS (p = 0.042; p = 0.019). Multivariate analysis including clinicopathological parameters did not reveal an independent prognostic character of CXCR4 expression. CXCR4 expression differs significantly within benign lesions and renal neoplasms. Cytoplasmic and nuclear expression of CXCR4 could be detected across all RCC subtypes. The prognostic value of CXCR4 in ccRCC was confirmed in univariate analysis.

Therapeutic Perspectives of HIV-Associated Chemokine Receptor (CCR5 and CXCR4) Antagonists in Carcinomas

The interaction between malignant cells and the tumor microenvironment is critical for tumor progression, and the chemokine ligand/receptor axes play a crucial role in this process. The CXCR4/CXCL12 and CCR5/CCL5 axes, both related to HIV, have been associated with the early (epithelial-mesenchymal transition and invasion) and late events (migration and metastasis) of cancer progression. In addition, these axes can also modulate the immune response against tumors. Thus, antagonists against the receptors of these axes have been proposed in cancer therapy. Although preclinical studies have shown promising results, clinical trials are needed to include these drugs in the oncological treatment protocols. New alternatives for these antagonists, such as dual CXCR4/CCR5 antagonists or combined therapy in association with immunotherapy, need to be studied in cancer therapy.

Utilization of macrocyclic peptides to target protein-protein interactions in cancer

Protein-protein interactions (PPIs) play vital roles in normal cellular processes. Dysregulated PPIs are involved in the process of various diseases, including cancer. Thus, these PPIs may serve as potential therapeutic targets in cancer treatment. However, despite rapid advances in small-molecule drugs and biologics, it is still hard to target PPIs, especially for those intracellular PPIs. Macrocyclic peptides have gained growing attention for their therapeutic properties in targeting dysregulated PPIs. Macrocyclic peptides have some unique features, such as moderate sizes, high selectivity, and high binding affinities, which make them good drug candidates. In addition, some oncology macrocyclic peptide drugs have been approved by the US Food and Drug Administration (FDA) for clinical use. Here, we reviewed the recent development of macrocyclic peptides in cancer treatment. The opportunities and challenges were also discussed to inspire new perspectives.

Small molecule inhibitors targeting the cancers

Compared with traditional therapies, targeted therapy has merits in selectivity, efficacy, and tolerability. Small molecule inhibitors are one of the primary targeted therapies for cancer. Due to their advantages in a wide range of targets, convenient medication, and the ability to penetrate into the central nervous system, many efforts have been devoted to developing more small molecule inhibitors. To date, 88 small molecule inhibitors have been approved by the United States Food and Drug Administration to treat cancers. Despite remarkable progress, small molecule inhibitors in cancer treatment still face many obstacles, such as low response rate, short duration of response, toxicity, biomarkers, and resistance. To better promote the development of small molecule inhibitors targeting cancers, we comprehensively reviewed small molecule inhibitors involved in all the approved agents and pivotal drug candidates in clinical trials arranged by the signaling pathways and the classification of small molecule inhibitors. We discussed lessons learned from the development of these agents, the proper strategies to overcome resistance arising from different mechanisms, and combination therapies concerned with small molecule inhibitors. Through our review, we hoped to provide insights and perspectives for the research and development of small molecule inhibitors in cancer treatment.

Targeting Cellular Components of the Tumor Microenvironment in Solid Malignancies

Simple Summary

The tumor microenvironment comprises numerous different cellular players that engage transformed cancer cells and may exert pro- vs anti-tumor functions. Their crosstalk, functionality, as well as cell recruitment to cancer lesions, is chiefly dictated by cytokines/chemokines-receptor pairs and these axes can represent therapeutic vulnerabilities—as for immune checkpoint blockers. In this review, we recapitulate the main drivers of cellular TME dynamics, interactions, and functionality, mainly focusing on T lymphocytes, macrophages and cancer associated fibroblasts, also providing an outlook on state-of-the-art TME-targeting agents.

Abstract

Cancers are composed of transformed cells, characterized by aberrant growth and invasiveness, in close relationship with non-transformed healthy cells and stromal tissue. The latter two comprise the so-called tumor microenvironment (TME), which plays a key role in tumorigenesis, cancer progression, metastatic seeding, and therapy resistance. In these regards, cancer-TME interactions are complex and dynamic, with malignant cells actively imposing an immune-suppressive and tumor-promoting state on surrounding, non-transformed, cells. Immune cells (both lymphoid and myeloid) can be recruited from the circulation and/or bone marrow by means of chemotactic signals, and their functionality is hijacked upon arrival at tumor sites. Molecular characterization of tumor-TME interactions led to the introduction of novel anti-cancer therapies targeting specific components of the TME, such as immune checkpoint blockers (ICB) (i.e., anti-programmed death 1, anti-PD1; anti-Cytotoxic T-Lymphocyte Antigen 4, anti-CTLA4). However, ICB resistance often develops and, despite the introduction of newer technologies able to study the TME at the single-cell level, a detailed understanding of all tumor-TME connections is still largely lacking. In this work, we highlight the main cellular and extracellular components of the TME, discuss their dynamics and functionality, and provide an outlook on the most relevant clinical data obtained with novel TME-targeting agents, with a focus on T lymphocytes, macrophages, and cancer-associated fibroblasts.

Identification of EZH2 as Cancer Stem Cell Marker in Clear Cell Renal Cell Carcinoma and the Anti-Tumor Effect of Epigallocatechin-3-Gallate (EGCG)

Simple Summary

Cancer stem cells (CSCs) refer to a group of undifferentiated heterogeneous tumor cells, defined as capable of self-renewal, differentiation, and may be linked to therapeutic resistance and tumor relapse. The development of novel therapeutic strategies to target CSCs and the identification of typical CSC markers are essential to improve therapy efficacy and prevent tumor relapse. Our study identifies CSC markers in renal cell carcinoma (RCC) and explores a potential treatment strategy and the underlying pharmacological mechanisms.

Abstract

The aim of the study was to develop a new therapeutic strategy to target cancer stem cells (CSCs) in clear cell renal cell carcinoma (ccRCC) and to identify typical CSC markers to improve therapy effectiveness. It was found that the corrected-mRNA expression-based stemness index was upregulated in kidney renal clear cell carcinoma (KIRC) tissues compared to non-tumor tissue and increased with higher tumor stage and grade. EZH2 was identified as a CSC marker and prognosis factor for KIRC patients. The expression of EZH2 was associated with several activated tumor-infiltrating immune cells. High expression of EZH2 was enriched in immune-related pathways, low expression was related to several metabolic pathways. Epigallocatechin-3-gallate (EGCG) was identified as the most potent suppressor of EZH2, was able to inhibit viability, migration, and invasion, and to increase the apoptosis rate of ccRCC CSCs. KIF11, VEGF, and MMP2 were identified as predictive EGCG target genes, suggesting a potential mechanism of how EZH2 might regulate invasiveness and migration. The percentages of FoxP3+ Treg cells in the peripheral blood mononuclear cells of ccRCC patients decreased significantly when cultured with spheres pretreated with EGCG plus sunitinib compared to spheres without treatment. Our findings provide new insights into the treatment options of ccRCC based on targeting CSCs.

Recent Advances in CXCL12/CXCR4 Antagonists and Nano-Based Drug Delivery Systems for Cancer Therapy

Chemokines can induce chemotactic cell migration by interacting with G protein-coupled receptors to play a significant regulatory role in the development of cancer. CXC chemokine-12 (CXCL12) can specifically bind to CXC chemokine receptor 4 (CXCR4) and is closely associated with the progression of cancer via multiple signaling pathways. Over recent years, many CXCR4 antagonists have been tested in clinical trials; however, Plerixafor (AMD3100) is the only drug that has been approved for marketing thus far. In this review, we first summarize the mechanisms that mediate the physiological effects of the CXCL12/CXCR4 axis. Then, we describe the use of CXCL12/CXCR4 antagonists. Finally, we discuss the use of nano-based drug delivery systems that exert action on the CXCL12/CXCR4 biological axis.

Harnessing cytokines and chemokines for cancer therapy

During the past 40 years, cytokines and cytokine receptors have been extensively investigated as either cancer targets or cancer treatments. A strong preclinical rationale supports therapeutic strategies to enhance the growth inhibitory and immunostimulatory effects of interferons and interleukins, including IL-2, IL-7, IL-12 and IL-15, or to inhibit the inflammatory and tumour-promoting actions of cytokines such as TNF, IL-1β and IL-6. This rationale is underscored by the discovery of altered and dysregulated cytokine expression in all human cancers. These findings prompted clinical trials of several cytokines or cytokine antagonists, revealing relevant biological activity but limited therapeutic efficacy. However, most trials involved patients with advanced-stage disease, which might not be the optimal setting for cytokine-based therapy. The advent of more effective immunotherapies and an increased understanding of the tumour microenvironment have presented new approaches to harnessing cytokine networks in the treatment of cancer, which include using cytokine-based therapies to enhance the activity or alleviate the immune-related toxicities of other treatments as well as to target early stage cancers. Many challenges remain, especially concerning delivery methods, context dependencies, and the pleiotropic, redundant and often conflicting actions of many cytokines. Herein, we discuss the lessons learnt from the initial trials of single-agent cytokine-based therapies and subsequent efforts to better exploit such agents for the treatment of solid tumours.

Impact of Value Frameworks on the Magnitude of Clinical Benefit: Evaluating a Decade of Randomized Trials for Systemic Therapy in Solid Malignancies

In the era of rapid development of new, expensive cancer therapies, value frameworks have been developed to quantify clinical benefit (CB). We assessed the evolution of CB since the 2015 introduction of The American Society of Clinical Oncology and The European Society of Medical Oncology value frameworks. Randomized clinical trials (RCTs) assessing systemic therapies for solid malignancies from 2010 to 2020 were evaluated and CB (Δ) in 2010–2014 (pre-value frameworks (PRE)) were compared to 2015–2020 (POST) for overall survival (OS), progression-free survival (PFS), response rate (RR), and quality of life (QoL). In the 485 studies analyzed (12% PRE and 88% POST), the most common primary endpoint was PFS (49%), followed by OS (20%), RR (12%), and QoL (6%), with a significant increase in OS and decrease in RR as primary endpoints in the POST era (p = 0.011). Multivariable analyses revealed significant improvement in ΔOS POST (OR 2.86, 95% CI 0.46 to 5.26, p = 0.02) while controlling for other variables. After the development of value frameworks, median ΔOS improved minimally. The impact of value frameworks has yet to be fully realized in RCTs. Efforts to include endpoints shown to impact value, such as QoL, into clinical trials are warranted.

Targeting monocytes/macrophages in fibrosis and cancer diseases: Therapeutic approaches

Over almost 140 years since their identification, the knowledge about macrophages has unbelievably evolved. The 'big eaters' from being thought of as simple phagocytic cells have been recognized as master regulators in immunity, homeostasis, healing/repair and organ development. Long considered to originate exclusively from bone marrow-derived circulating monocytes, macrophages have been also demonstrated to be the first immune cells colonizing tissues in the developing embryo and persisting in adult life by self-renewal, as long-lived tissue resident macrophages. Therefore, heterogeneous populations of macrophages with different ontogeny and functions co-exist in tissues. Macrophages act as sentinels of homeostasis and are intrinsically programmed to lead the wound healing and repair processes that occur after injury. However, in certain pathological circumstances macrophages get dysfunctional, and impaired or aberrant macrophage activities become key features of diseases. For instance, in both fibrosis and cancer, that have been defined 'wounds that do not heal', dysfunctional monocyte-derived macrophages overall play a key detrimental role. On the other hand, due to their plasticity these cells can be 're-educated' and exert anti-fibrotic and anti-cancer functions. Therefore macrophages represent an important therapeutic target in both fibrosis and cancer diseases. The current review will illustrate new insights into the role of monocytes/macrophages in these devastating diseases and summarize new therapeutic strategies and applications of macrophage-targeted drug development in their clinical setting.

Anticancer opportunities at every stage of chemokine function

The chemokine system, comprising 48 chemokines and 23 receptors, is critically involved in several hallmarks of cancer. Yet, despite extensive efforts from the pharmaceutical sector, only two drugs aimed at this system are currently approved for clinical use against cancer. To date, numerous pharmacological approaches have been developed to successfully intervene at different stages of chemokine function: (i) chemokine availability; (ii) chemokine-glycosaminoglycan binding; and (iii) chemokine receptor binding. Many of these strategies have been tested in preclinical cancer models, and some have advanced to clinical trials as potential anticancer therapies. Here we will review the strategies and growing pharmacological toolbox for manipulating the chemokine system in cancer, and address novel methods poised for future (pre)clinical testing.

At the Bench: Pre-clinical evidence for multiple functions of CXCR4 in cancer

Signaling through chemokine receptor, C-X-C chemokine receptor type 4 (CXCR4) regulates essential processes in normal physiology, including embryogenesis, tissue repair, angiogenesis, and trafficking of immune cells. Tumors co-opt many of these fundamental processes to directly stimulate proliferation, invasion, and metastasis of cancer cells. CXCR4 signaling contributes to critical functions of stromal cells in cancer, including angiogenesis and multiple cell types in the tumor immune environment. Studies in animal models of several different types of cancers consistently demonstrate essential functions of CXCR4 in tumor initiation, local invasion, and metastasis to lymph nodes and distant organs. Data from animal models support clinical observations showing that integrated effects of CXCR4 on cancer and stromal cells correlate with metastasis and overall poor prognosis in >20 different human malignancies. Small molecules, Abs, and peptidic agents have shown anticancer efficacy in animal models, sparking ongoing efforts at clinical translation for cancer therapy. Investigators also are developing companion CXCR4-targeted imaging agents with potential to stratify patients for CXCR4-targeted therapy and monitor treatment efficacy. Here, pre-clinical studies demonstrating functions of CXCR4 in cancer are reviewed.

Cancer stem cells targets and combined therapies to prevent cancer recurrence

Cancer stem cells (CSCs) control the dynamics of tumorigenesis by self-renewal ability and differentiation potential. These properties contribute towards tumor malignancy, metastasis, cellular heterogeneity, and immune escape, which are regulated by multiple signaling pathways. The CSCs are chemoresistant and cause cancer recurrence, generally recognized as a small side-population that eventually leads to tumor relapse. Despite many treatment options available, none can be considered entirely efficient due to a lack of specificity and dose limitation. This review primarily highlights the processes involved in CSCs development and maintenance. Secondly, the current effective therapies based on stem cells, cell-free therapies that involve exosomes and miRNAs, and photodynamic therapy have been discussed. Also, the inhibitors that specifically target various signaling pathways, which can be used in combination to control CSCs kinetics have been highlighted. Conclusively, this comprehensive review is a detailed study of recently developed novel treatment strategies that will facilitate in coming up with better-targeted approaches against CSCs.

Update of early phase clinical trials in cancer immunotherapy

Immunotherapy has revolutionized the landscape of cancer treatment and become a standard pillar of the treatment. The two main drivers, immune checkpoint inhibitors and chimeric antigen receptor T cells, contributed to this unprecedented success. However, despite the striking clinical improvements, most patients still suffer from disease progression because of the evolution of primary or acquired resistance. This mini-review summa-rizes new treatment options including novel targets and interesting combinational approaches to increase our understanding of the mechanisms of the action of and resistance to immunotherapy, to expand our knowledge of advances in biomarker and therapeutics development, and to help to find the most appropriate option or a way of overcoming the resistance for cancer patients.

CXCR4 expression in lung carcinogenesis: Evaluating gender-specific differences in survival outcomes based on CXCR4 expression in early stage non-small cell lung cancer patients

INTRODUCTION

Evidence suggests that the expression of certain cytokine receptors increases with lung cancer evolution. Overexpression of the cytokine receptor CXCR4 is associated with poor outcomes in stage IV non-small cell lung cancer (NSCLC), with shorter survival in females with high CXCR4 expression. This study quantifies CXCR4 expression in early stage disease and evaluates its association with gender-specific recurrence-free (RFS) and overall survival (OS) in resected stage I-III NSCLC patients.

METHODS

Patient characteristics and clinical outcomes were obtained from the Glans-Look Lung Cancer (G-LLC) database for early stage NSCLC patients diagnosed between 2003-2006 at the Tom Baker Cancer Centre (TBCC). CXCR4 expression was quantified on tissue microarrays (TMA). Median RFS and OS were evaluated by gender using Kaplan-Meier analyses. CXCR4 expression and outcome data were analyzed using Cox proportional hazards (PH) and multi-state models (MSM).

RESULTS

176 stage I-III NSCLC patients were identified. CXCR4 expression was lower in early stage NSCLC patients, with a mean CXCR4 expression of 1729 (SD 1083) compared to 2640 (SD 1541) in stage IV patients. On Kaplan-Meier, median RFS by gender was similar (male 52.8 months vs. female 54.5 months) as was median OS (male 80.9 months vs. female 89.0 months), and there was no significant difference in RFS (p = 0.60) or OS (p = 0.30) by gender and CXCR4 groups over follow-up. By multivariable analysis, CXCR4 expression was not prognostic for RFS (Hazard Ratio (HR) = 1.00, p = 0.73) or OS (HR = 1.00, p = 0.44), and no gender difference was observed.

CONCLUSIONS

CXCR4 expression increases with stage progression in NSCLC but is not prognostic in early stage NSCLC patients of either gender. Mechanisms by which CXCR4 expression increases during lung carcinogenesis warrant further exploration and testing in clinical trials.

Update of early phase clinical trials in cancer immunotherapy

Immunotherapy has revolutionized the landscape of cancer treatment and become a standard pillar of the treatment. The two main drivers, immune checkpoint inhibitors and chimeric antigen receptor T cells, contributed to this unprecedented success. However, despite the striking clinical improvements, most patients still suffer from disease progression because of the evolution of primary or acquired resistance. This mini-review summarizes new treatment options including novel targets and interesting combinational approaches to increase our understanding of the mechanisms of the action of and resistance to immunotherapy, to expand our knowledge of advances in biomarker and therapeutics development, and to help to find the most appropriate option or a way of overcoming the resistance for cancer patients. [BMB Reports 2021; 54(1): 70-88].

The CXCL12-CXCR4 Signaling Axis Plays a Key Role in Cancer Metastasis and is a Potential Target for Developing Novel Therapeutics against Metastatic Cancer

Metastasis is the main cause of death in cancer patients; there is currently no effective treatment for cancer metastasis. This is primarily due to our insufficient understanding of the metastatic mechanisms in cancer. An increasing number of studies have shown that the C-X-C motif chemokine Ligand 12 (CXCL12) is overexpressed in various tissues and organs. It is a key niche factor that nurtures the pre-metastatic niches (tumorigenic soil) and recruits tumor cells (oncogenic "seeds") to these niches, thereby fostering cancer cell aggression and metastatic capabilities. However, the C-X-C motif chemokine Receptor 4 (CXCR4) is aberrantly overexpressed in various cancer stem/progenitor cells and functions as a CXCL12 receptor. CXCL12 activates CXCR4 as well as multiple downstream multiple tumorigenic signaling pathways, promoting the expression of various oncogenes. Activation of the CXCL12-CXCR4 signaling axis promotes Epithelial-Mesenchymal Transition (EMT) and mobilization of cancer stem/progenitor cells to pre-metastatic niches. It also nurtures cancer cells with high motility, invasion, and dissemination phenotypes, thereby escalating multiple proximal or distal cancer metastasis; this results in poor patient prognosis. Based on this evidence, recent studies have explored either CXCL12- or CXCR4-targeted anti-cancer therapeutics and have achieved promising results in the preclinical trials. Further exploration of this new strategy and its potent therapeutics effect against metastatic cancer through the targeting of the CXCL12- CXCR4 signaling axis may lead to a novel therapy that can clean up the tumor microenvironment ("soil") and kill the cancer cells, particularly the cancer stem/progenitor cells ("seeds"), in cancer patients. Ultimately, this approach has the potential to effectively treat metastatic cancer.

Targeted Delivery of Therapeutics to Urological Cancer Stem Cells

Urological cancer refers to cancer in organs of the urinary system and the male reproductive system. It mainly includes prostate cancer, bladder cancer, renal cancer, etc., seriously threatening patients' survival. Although there are many advances in the treatment of urological cancer, approved targeted therapies often result in tumor recurrence and therapy failure. An increasing amount of evidence indicated that cancer stem cells (CSCs) with tumor-initiating ability were the source of treatment failure in urological cancer. The development of CSCstargeted strategy can provide a possibility for the complete elimination of urological cancer. This review is based on a search of PubMed, Google scholar and NIH database (http://ClinicalTrials.gov/) for English language articles containing the terms: "biomarkers", "cancer stem cells", "targeting/targeted therapy", "prostate cancer", bladder cancer" and "kidney cancer". We summarized the biomarkers and stem cell features of the prostate, bladder and renal CSCs, outlined the targeted strategies for urological CSCs from signaling pathways, cytokines, angiogenesis, surface markers, elimination therapy, differentiation therapy, immunotherapy, microRNA, nanomedicine, etc., and highlighted the prospects and future challenges in this research field.

Targeting Strategies for Renal Cancer Stem Cell Therapy

Renal cell carcinoma (RCC) is an intractable genitourinary malignancy that accounts for approximately 4% of adult malignancies. Currently, there is no approved targeted therapy for RCC that has yielded durable remissions, and they remain palliative in intent. Emerging evidence has indicated that renal tumorigenesis and RCC treatment-resistance may originate from renal cancer stem cells (CSCs) with tumor-initiating capacity (CSC hypothesis). A better understanding of the mechanism underlying renal CSCs will help to dissect RCC heterogeneity and drug treatment efficiency, to promote more personalized and targeted therapies. In this review, we summarized the stem cell characteristics of renal CSCs. We outlined the targeting strategies and challenges associated with developing therapies that target renal CSCs angiogenesis, immunosuppression, signaling pathways, surface biomarkers, microRNAs and nanomedicine. In conclusion, CSCs are an important role in renal carcinogenesis and represent a valid target for treatment of RCC patients.

Targeted therapy for metastatic renal cell carcinoma

BACKGROUND

Several comparative randomised controlled trials (RCTs) have been performed including combinations of tyrosine kinase inhibitors (TKIs) and immune checkpoint inhibitors since the publication of a Cochrane Review on targeted therapy for metastatic renal cell carcinoma (mRCC) in 2008. This review represents an update of that original review.

OBJECTIVES

To assess the effects of targeted therapies for clear cell mRCC in patients naïve to systemic therapy.

SEARCH METHODS

We performed a comprehensive search with no restrictions on language or publication status. The date of the latest search was 18 June 2020.

SELECTION CRITERIA

We included randomised controlled trials, recruiting patients with clear cell mRCC naïve to previous systemic treatment. The index intervention was any TKI-based targeted therapy.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the included studies and extracted data for the primary outcomes: progression-free survival (PFS), overall survival (OS) and serious adverse events (SAEs); and the secondary outcomes: health-related quality of life (QoL), response rate and minor adverse events (AEs). We performed statistical analyses using a random-effects model and rated the certainty of evidence according to the GRADE approach.

MAIN RESULTS

We included 18 RCTs reporting on 11,590 participants randomised across 18 comparisons. This abstract focuses on the primary outcomes of select comparisons. 1. Pazopanib versus sunitinib Pazopanib may result in little to no difference in PFS as compared to sunitinib (hazard ratio (HR) 1.05, 95% confidence interval (CI) 0.90 to 1.23; 1 study, 1110 participants; low-certainty evidence). Based on the control event risk of 420 per 1000 in this trial at 12 months, this corresponds to 18 fewer participants experiencing PFS (95% CI 76 fewer to 38 more) per 1000 participants. Pazopanib may result in little to no difference in OS compared to sunitinib (HR 0.92, 95% CI 0.80 to 1.06; 1 study, 1110 participants; low-certainty evidence). Based on the control event risk of 550 per 1000 in this trial at 12 months, this corresponds to 27 more OSs (95% CI 19 fewer to 70 more) per 1000 participants. Pazopanib may result in little to no difference in SAEs as compared to sunitinib (risk ratio (RR) 1.01, 95% CI 0.94 to 1.09; 1 study, 1102 participants; low-certainty evidence). Based on the control event risk of 734 per 1000 in this trial, this corresponds to 7 more participants experiencing SAEs (95% CI 44 fewer to 66 more) per 1000 participants. 2. Sunitinib versus avelumab and axitinib Sunitinib probably reduces PFS as compared to avelumab plus axitinib (HR 1.45, 95% CI 1.17 to 1.80; 1 study, 886 participants; moderate-certainty evidence). Based on the control event risk of 550 per 1000 in this trial at 12 months, this corresponds to 130 fewer participants experiencing PFS (95% CI 209 fewer to 53 fewer) per 1000 participants. Sunitinib may result in little to no difference in OS (HR 1.28, 95% CI 0.92 to 1.79; 1 study, 886 participants; low-certainty evidence). Based on the control event risk of 890 per 1000 in this trial at 12 months, this would result in 29 fewer OSs (95% CI 78 fewer to 8 more) per 1000 participants. Sunitinib may result in little to no difference in SAEs (RR 1.01, 95% CI 0.93 to 1.10; 1 study, 873 participants; low-certainty evidence). Based on the control event risk of 705 per 1000 in this trial, this corresponds to 7 more SAEs (95% CI 49 fewer to 71 more) per 1000 participants.  3. Sunitinib versus pembrolizumab and axitinib Sunitinib probably reduces PFS as compared to pembrolizumab plus axitinib (HR 1.45, 95% CI 1.19 to 1.76; 1 study, 861 participants; moderate-certainty evidence). Based on the control event risk of 590 per 1000 in this trial at 12 months, this corresponds to 125 fewer participants experiencing PFS (95% CI 195 fewer to 56 fewer) per 1000 participants. Sunitinib probably reduces OS (HR 1.90, 95% CI 1.36 to 2.65; 1 study, 861 participants; moderate-certainty evidence). Based on the control event risk of 880 per 1000 in this trial at 12 months, this would result in 96 fewer OSs (95% CI 167 fewer to 40 fewer) per 1000 participants. Sunitinib may reduce SAEs as compared to pembrolizumab plus axitinib (RR 0.90, 95% CI 0.81 to 1.02; 1 study, 854 participants; low-certainty evidence) although the CI includes the possibility of no effect. Based on the control event risk of 604 per 1000 in this trial, this corresponds to 60 fewer SAEs (95% CI 115 fewer to 12 more) per 1000 participants.  4. Sunitinib versus nivolumab and ipilimumab Sunitinib may reduce PFS as compared to nivolumab plus ipilimumab (HR 1.30, 95% CI 1.11 to 1.52; 1 study, 847 participants; low-certainty evidence). Based on the control event risk of 280 per 1000 in this trial at 30 months' follow-up, this corresponds to 89 fewer PFSs (95% CI 136 fewer to 37 fewer) per 1000 participants. Sunitinib reduces OS (HR 1.52, 95% CI 1.23 to 1.89; 1 study, 847 participants; high-certainty evidence). Based on the control event risk 600 per 1000 in this trial at 30 months, this would result in 140 fewer OSs (95% CI 219 fewer to 67 fewer) per 1000 participants. Sunitinib probably increases SAEs (RR 1.37, 95% CI 1.22 to 1.53; 1 study, 1082 participants; moderate-certainty evidence). Based on the control event risk of 457 per 1000 in this trial, this corresponds to 169 more SAEs (95% CI 101 more to 242 more) per 1000 participants.

AUTHORS' CONCLUSIONS

Based on the low to high certainty of evidence, several combinations of immune checkpoint inhibitors appear to be superior to single-agent targeted therapy in terms of PFS and OS, and with a favourable AE profile. Some single-agent targeted therapies demonstrated a similar or improved oncological outcome compared to others; minor differences were observed for AE within this group. The certainty of evidence was variable ranging from high to very low and all comparisons were based on single trials.

Relevance of the CXCR4/CXCR7-CXCL12 axis and its effect in pathophysiological conditions

The impact of the C-X-C receptor (CXCR) 7 and its close co-player CXCR4 in different physiological and pathophysiological processes has been extensively investigated within the last decades. Following activation by their shared ligand C-X-C ligand (CXCL) 12, both chemokine receptors can induce various routes of cell signaling and/or scavenge CXCL12 from the extracellular environment. This contributes to organ development and maintenance of homeostasis. Alterations of the CXCR4/CXCR7-CXCL12 axis have been detected in diseases such as cancer, central nervous system and cardiac disorders, and autoimmune diseases. These alterations include changes of the expression pattern, distribution, or downstream effects. The progression of the diseases can be regulated in preclinical models by the use of various modulators suggesting that this axis serves as a promising therapeutic target. It is therefore of great interest to investigate CXCR4/CXCR7/CXCL12 modulators in clinical development, with several CXCR4 and CXCL12 modulators such as plerixafor, ulocuplumab, balixafortide, and olaptesed pegol having already reached this stage. An overview is presented of the most important diseases whose outcomes can be positively or negatively regulated by the CXCR4/CXCR7-CXCL12 axis and summarizes preclinical and clinical data of modulators of that axis. Contrary to CXCR4 and CXCL12 modulators, CXCR7 modulators have, thus far, not been extensively studied. Therefore, more (pre)clinical investigations are needed.

Synthetic CXCR4 Antagonistic Peptide Assembling with Nanoscaled Micelles Combat Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is the most common adult acute leukemia with very low survival rate due to drug resistance and high relapse rate. The C-X-C chemokine receptor 4 (CXCR4) is highly expressed by AML cells, actively mediating chemoresistance and reoccurrence. Herein, a chemically synthesized CXCR4 antagonistic peptide E5 is fabricated to micelle formulation (M-E5) and applied to refractory AML mice, and its therapeutic effects and pharmacokinetics are investigated. Results show that M-E5 can effectively block the surface CXCR4 in leukemic cells separated from bone marrow (BM) and spleen, and inhibit the C-X-C chemokine ligand 12-mediated migration. Subcutaneous administration of M-E5 significantly inhibits the engraftment of leukemic cells in spleen and BM, and mobilizes residue leukemic cells into peripheral blood, reducing organs' burden and significantly prolonging the survival of AML mice. M-E5 can also increase the efficacy of combining regime of homoharringtonine and doxorubicin. Ribonucleic acid sequencing demonstrates that the therapeutic effect is contributed by inhibiting proliferation and enhancing apoptosis and differentiation, all related to the CXCR4 signaling blockade. M-E5 reaches the concentration peak at 2 h after administration with a half-life of 14.5 h in blood. In conclusion, M-E5 is a novel promising therapeutic candidate for refractory AML treatment.

Safety and Pharmacokinetics of CXCR4 Peptide Antagonist, LY2510924, in Combination with Durvalumab in Advanced Refractory Solid Tumors

Purpose: This was an open-label phase 1a study assessing the maximum tolerated dose (MTD), safety, and tolerability of CXCR4 peptide antagonist, LY2510924, administered in combination with durvalumab in patients with advanced refractory solid tumors.

Methods: Patients received LY2510924 at 20, 30, or 40 mg subcutaneous (SC) once daily in combination with durvalumab at 1500 mg intravenously (IV) on day 1 of each 28-day cycle. The primary objective was to assess the MTD and safety of LY2510924 SC daily in combination with durvalumab in patients with advanced (metastatic and/or unresectable) solid tumors. Secondary objectives included pharmacokinetics (PK) and the antitumor activity of LY2510924 in combination with durvalumab. Exploratory objectives were biomarker analysis, including pharmacodynamic markers, relevant to LY2510924 and durvalumab, including immune functioning, drug targets, cancer-related pathways, and the disease state.

Results: Nine patients (three each at 20, 30, and 40 mg) were enrolled in the study (eight patients with pancreatic cancer and one patient with rectal cancer). The majority of patients completed one or two cycles (100.0% ≥ 1 cycle; 88.9% ≥ 2 cycles) of LY2510924 and durvalumab. No dose limiting toxicities were reported. Most common (>10%) treatment-emergent adverse events were injection-site reaction (44.4%), fatigue (33.3%), and increased white blood cell count (33.3%). PK parameters for combination were similar to those reported in previous studies when given as monotherapy. Best overall response of stable disease was observed in four (44.4%) patients and one patient had unconfirmed partial response.

Conclusion: The recommended phase 2 dose is 40 mg SC once-daily LY2510924 in combination with durvalumab 1500 mg IV and showed acceptable safety and tolerability in patients with advanced refractory tumors.

KISS1 in breast cancer progression and autophagy

Tumor suppressors are cellular proteins typically expressed in normal (non-cancer) cells that not only regulate such cellular functions as proliferation, migration and adhesion, but can also be secreted into extracellular space and serve as biomarkers for pathological conditions or tumor progression. KISS1, a precursor for several shorter peptides, known as metastin (Kisspeptin-54), Kisspeptin-14, Kisspeptin-13 and Kisspeptin-10, is one of those metastasis suppressor proteins, whose expression is commonly downregulated in the metastatic tumors of various origins. The commonly accepted role of KISS1 in metastatic tumor progression mechanism is the ability of this protein to suppress colonization of disseminated cancer cells in distant organs critical for the formation of the secondary tumor foci. Besides, recent evidence suggests involvement of KISS1 in the mechanisms of tumor angiogenesis, autophagy and apoptosis regulation, suggesting a possible role in both restricting and promoting cancer cell invasion. Here, we discuss the role of KISS1 in regulating metastases, the link between KISS1 expression and the autophagy-related biology of cancer cells and the perspectives of using KISS1 as a potential diagnostic marker for cancer progression as well as a new anti-cancer therapeutics.

Targeting cancer stem cell pathways for cancer therapy

Since cancer stem cells (CSCs) were first identified in leukemia in 1994, they have been considered promising therapeutic targets for cancer therapy. These cells have self-renewal capacity and differentiation potential and contribute to multiple tumor malignancies, such as recurrence, metastasis, heterogeneity, multidrug resistance, and radiation resistance. The biological activities of CSCs are regulated by several pluripotent transcription factors, such as OCT4, Sox2, Nanog, KLF4, and MYC. In addition, many intracellular signaling pathways, such as Wnt, NF-κB (nuclear factor-κB), Notch, Hedgehog, JAK-STAT (Janus kinase/signal transducers and activators of transcription), PI3K/AKT/mTOR (phosphoinositide 3-kinase/AKT/mammalian target of rapamycin), TGF (transforming growth factor)/SMAD, and PPAR (peroxisome proliferator-activated receptor), as well as extracellular factors, such as vascular niches, hypoxia, tumor-associated macrophages, cancer-associated fibroblasts, cancer-associated mesenchymal stem cells, extracellular matrix, and exosomes, have been shown to be very important regulators of CSCs. Molecules, vaccines, antibodies, and CAR-T (chimeric antigen receptor T cell) cells have been developed to specifically target CSCs, and some of these factors are already undergoing clinical trials. This review summarizes the characterization and identification of CSCs, depicts major factors and pathways that regulate CSC development, and discusses potential targeted therapy for CSCs.

Clinical Efficacy and Complication Rate of Sunitinib 2/1 Versus 4/2 Schedule for the Treatment of Metastatic Renal Cell Cancer: A Systematic Review and Meta-Analysis

The treatment of renal cell carcinoma has achieved certain curative effects with the innovation of clinical drugs, such as sunitinib. However, the clinical efficacy and complication rate of the sunitinib 2/1 and 4/2 schedule in metastatic renal cell cancer remain unclear. In this study we aimed to resolve this issue by using meta-analysis to provide more theoretical guidance for clinical use. Several outcome measurements were included in this study to compare the 2 schedules such as complete response, partial response, stable disease, progressive disease, progression-free survival, overall survival, and complications. In the contrast analysis, the sunitinib 2/1 and 4/2 schedule resulted in significant improvements in prognosis. However, the sunitinib 2/1 schedule was superior to the 4/2 schedule in terms of controlling stable disease and causing fewer complications.

Cancer-associated fibroblasts as key regulators of the breast cancer tumor microenvironment

Tumor cells exist in close proximity with non-malignant cells. Extensive and multilayered crosstalk between tumor cells and stromal cells tailors the tumor microenvironment (TME) to support survival, growth, and metastasis. Fibroblasts are one of the largest populations of non-malignant host cells that can be found within the TME of breast, pancreatic, and prostate tumors. Substantial scientific evidence has shown that these cancer-associated fibroblasts (CAFs) are not only associated with tumors by proximity but are also actively recruited to developing tumors where they can influence other cells of the TME as well as influencing tumor cell survival and metastasis. This review discusses the impact of CAFs on breast cancer biology and highlights their heterogeneity, origin and their role in tumor progression, ECM remodeling, therapy resistance, metastasis, and the challenges ahead of targeting CAFs to improve therapy response.

Resolution of Gastric Cancer-Promoting Inflammation: A Novel Strategy for Anti-cancer Therapy

The connection between inflammation and cancer was initially recognized by Rudolf Virchow in the nineteenth century. During the last decades, a large body of evidence has provided support to his hypothesis, and now inflammation is recognized as one of the hallmarks of cancer, both in etiopathogenesis and ongoing tumor growth. Infection with the pathogen Helicobacter pylori is the primary causal factor in 90% of gastric cancer (GC) cases. As we increase our understanding of how chronic inflammation develops in the stomach and contributes to carcinogenesis, there is increasing interest in targeting cancer-promoting inflammation as a strategy to treat GC. Moreover, once cancer develops and anti-cancer immune responses are suppressed, there is evidence of a substantial shift in the microenvironment and new targets for immune therapy emerge. In this chapter, we provide insight into inflammation-related factors, including T lymphocytes, macrophages, pro-inflammatory chemokines, and cytokines, which promote H. pylori-associated GC initiation and growth. While intervening with chronic inflammation is not a new practice in rheumatology or gastroenterology, this approach has not been fully explored for its potential to prevent carcinogenesis or to contribute to the treatment of GC. This review highlights current and possible strategies for therapeutic intervention including (i) targeting pro-inflammatory mediators, (ii) targeting growth factors and pathways involved in angiogenesis in the gastric tumor microenvironment, and (iii) enhancing anti-tumor immunity. In addition, we highlight a significant number of clinical trials and discuss the importance of individual tumor characterization toward offering personalized immune-related therapy.

CXCR4 Based Therapeutics for Non-Small Cell Lung Cancer (NSCLC)

Lung cancer is the second most common malignancy. Unfortunately, despite advances in multimodality therapeutics for the disease, the overall five-year survival rate among newly diagnosed lung cancer patients remains in the range region of 15%. In addition, although immune checkpoint inhibitors are increasingly being incorporated into lung cancer treatment protocols, the proportion of patients that respond to these agents remains low and the duration of response is often short. Therefore, novel methodologies to enhance the efficacy of immunotherapy in lung cancer are highly desirable. Chemokines are small chemotactic cytokines that interact with their 7 transmembrane G-protein⁻coupled receptors, to guide immune cell trafficking in the body under both physiologic and pathologic conditions. Tumor cells highjack a small repertoire of the chemokine/chemokine receptor system and utilize it in a manner that benefits local tumor growth and distant spread. The chemokine receptor, CXCR4 is expressed in over 30 types of malignant tumors and, through interaction with its ligand CXCL12, was shown exert pleotropic pro-tumorigenic effects. In this review, the pathologic roles that CXCL12/CXCR4 play in lung cancer propagation are presented. Furthermore, the challenges and potential benefits of incorporating drugs that target CXCL12/CXCR4 into immune-based lung cancer therapeutic protocols are discussed.

Emerging strategies for combination checkpoint modulators in cancer immunotherapy

Current immune checkpoint-modulating agents have demonstrated clinical efficacy in certain tumor types, particularly those with a high burden of tumor-specific neoantigens, high tumor-mutational burden, and abundant tumor-infiltrating T cells. However, these tumors often stop responding, with signs of T cells exhaustion, decreased T cell effector function, and upregulated inhibitory checkpoints. To enhance antitumor immunity and rescue exhausted T cells, newer inhibitory and stimulatory checkpoint modulators are being tested as monotherapy or in combination with approved checkpoint inhibitors. In contrast, tumors with low tumor-mutational burden, low neoantigen burden, and a paucity of T cells are immunologically "cold," and therefore first require the addition of agents to facilitate the induction of T cells into tumors. Cold tumors also often recruit immunosuppressive cell subsets, including regulatory T cells, myeloid-derived suppressor cells, and macrophages, and secrete immunosuppressive soluble cytokines, chemokines, and metabolites. To unleash an optimal antitumor immune response, combinatorial therapeutics that combine immune checkpoints with other modalities, such as vaccines, are being developed. From current preclinical data, it appears that combinatorial strategies will provide robust and durable responses in patients with immunologically cold cancers.

CXCR4 antagonist AMD3100 enhances the response of MDA-MB-231 triple-negative breast cancer cells to ionizing radiation

Radiation therapy (RT) is one of the primary modalities for triple-negative breast cancer (TNBC) treatment. However, due to the pro-metastatic potential of radiation and the intrinsic radiation resistance of some tumors, many patients experience RT failure, which leads to cancer relapse and distant metastasis. This preclinical study evaluated the efficacy of the antagonist of the SDF-1 receptor CXCR4, AMD3100, as a radiosensitizer in TNBC models. The combined effect of ionizing radiation and AMD3100 was determined in vitro by surviving fraction, cell cycle distribution, Bax and Bcl-2 expression, and apoptosis assays in a TNBC cell line (MDA-MB-231). For in vivo studies, human xenograft athymic nude mice were used. Treatment of TNBC cells with AMD3100 significantly augmented cellular radiosensitivity. Radiosensitivity was enhanced specifically through increased Bax expression, reduced Bcl-2 expression, prolonged G2-M arrest, and increased apoptosis. Combined treatment with AMD3100 and irradiation also enhanced tumor growth delay, with an enhancement factor ranging from 1.5 to 1.8. These findings support the evaluation of antagonists of the SDF-1 receptor CXCR4, such as AMD3100, as potent radiosensitizers in TNBC.

Population Pharmacokinetic and Pharmacodynamic Modeling of LY2510924 in Patients With Advanced Cancer

The objectives of this study were to characterize the pharmacokinetics (PK) of LY2510924, a potent peptide antagonist of the CXCR4 receptor, after subcutaneous administration in patients with advanced cancer forms and quantify LY2510924 stimulatory effects on the mobilization of cells bearing the cluster of differentiation 34 (CD34) as an indirect reflection of the chemokine C-X-C motif ligand 12/CXCR4 axis inhibition. LY2510924 PK were best characterized by a two-compartment model with first-order absorption and dose-dependent clearance predicting steady state after three daily doses and little accumulation (accumulation ratio <1.17). The dynamics of CD34+ cell counts were best characterized with a precursor model with reversible transfer from the precursor to the central compartment and LY2510924-driven stimulation of cell mobilization. Model-based simulations show that once-daily doses of 20 mg LY2510924 produce maximum CD34+ cell response and that peak effect typically occurs after three daily doses and slowly wanes over time.

Targeting Strategies for Renal Cell Carcinoma: From Renal Cancer Cells to Renal Cancer Stem Cells

Renal cell carcinoma (RCC) is a common form of urologic tumor that originates from the highly heterogeneous epithelium of renal tubules. Over the last decade, targeting therapies to renal cancer cells have transformed clinical care for RCC. Recently, it was proposed that renal cancer stem cells (CSCs) isolated from renal carcinomas were responsible for driving tumor growth and resistance to conventional chemotherapy and radiotherapy, according to the theory of CSCs; this has provided the rationale for therapies targeting this aggressive cell population. Precise identification of renal CSC populations and the complete cell hierarchy will accurately inform characterization of disease subtypes. This will ultimately contribute to more personalized and targeted therapies. Here, we summarize potential targeting strategies for renal cancer cells and renal CSCs, including tyrosine kinase inhibitors, mammalian target of rapamycin inhibitors (mTOR), interleukins, CSC marker inhibitors, bone morphogenetic protein-2, antibody drug conjugates, and nanomedicine. In conclusion, targeting therapies for RCC represent new directions for exploration and clinical investigation and they plant a seed of hope for advanced clinical care.