Lucitanib for the Treatment of HR+/HER2− Metastatic Breast Cancer: Results from the Multicohort Phase II FINESSE Study

Fibroblast growth factor receptor signaling in estrogen receptor-positive breast cancer: mechanisms and role in endocrine resistance

Fibroblast Growth Factor Receptors (FGFRs) play a significant role in Estrogen Receptor-positive (ER+) breast cancer by contributing to tumorigenesis and endocrine resistance. This review explores the structure, signaling pathways, and implications of FGFRs, particularly FGFR1, FGFR2, FGFR3, and FGFR4, in ER+ breast cancer. FGFR1 is frequently amplified, especially in aggressive Luminal B-like tumors, and its amplification is associated with poor prognosis and treatment resistance. The co-amplification of FGFR1 with oncogenes like EIF4EBP1 and NSD3 complicates its role as a standalone oncogenic driver. FGFR2 amplification, though less common, is critical in hormone receptor regulation, driving proliferation and treatment resistance. FGFR3 and FGFR4 also contribute to endocrine resistance through various mechanisms, including the activation of alternate signaling pathways like PI3K/AKT/mTOR and RAS/RAF/MEK/ERK. Endocrine resistance remains a major clinical challenge, with around 70% of breast cancers initially hormone receptor positive. Despite the success of CDK 4/6 inhibitors in combination with endocrine therapy (ET), resistance often develops, necessitating new treatment strategies. FGFR inhibitors have shown potential in preclinical studies, but clinical trials have yielded limited success due to off-target toxicities and lack of predictive biomarkers. Current clinical trials, including those evaluating FGFR inhibitors like erdafitinib, lucitanib, and dovitinib, have demonstrated mixed outcomes, underscoring the complexity of FGFR signaling in breast cancer. The interplay between FGFR and other signaling pathways highlights the need for comprehensive molecular profiling and personalized treatment approaches. Future research should focus on identifying robust biomarkers and developing combination therapies to enhance the efficacy of FGFR-targeted treatments. In conclusion, targeting FGFR signaling in ER+ breast cancer presents both challenges and opportunities. A deeper understanding of the molecular mechanisms and resistance pathways is crucial for the successful integration of FGFR inhibitors into clinical practice, aiming to improve outcomes for patients with endocrine-resistant breast cancer.

Targeting FGFR for cancer therapy

The FGFR signaling pathway is integral to cellular activities, including proliferation, differentiation, and survival. Dysregulation of this pathway is implicated in numerous human cancers, positioning FGFR as a prominent therapeutic target. Here, we conduct a comprehensive review of the function, signaling pathways and abnormal alterations of FGFR, as well as its role in tumorigenesis and development. Additionally, we provide an in-depth analysis of pivotal phase 2 and 3 clinical trials evaluating the performance and safety of FGFR inhibitors in oncology, thereby shedding light on the current state of clinical research in this field. Then, we highlight four drugs that have been approved for marketing by the FDA, offering insights into their molecular mechanisms and clinical achievements. Our discussion encompasses the intricate landscape of FGFR-driven tumorigenesis, current techniques for pinpointing FGFR anomalies, and clinical experiences with FGFR inhibitor regimens. Furthermore, we discuss the inherent challenges of targeting the FGFR pathway, encompassing resistance mechanisms such as activation by gatekeeper mutations, alternative pathways, and potential adverse reactions. By synthesizing the current evidence, we underscore the potential of FGFR-centric therapies to enhance patient prognosis, while emphasizing the imperative need for continued research to surmount resistance and optimize treatment modalities.

Exploring FGFR signaling inhibition as a promising approach in breast cancer treatment

As our grasp of cancer genomics deepens, we are steadily progressing towards the domain of precision medicine, where targeted therapy stands out as a revolutionary breakthrough in the landscape of cancer therapeutics. The fibroblast growth factor receptors (FGFR) pathway has been unveiled as a fundamental instigator in the pathophysiological mechanisms underlying breast carcinoma, paving the way for the exhilarating development of precision-targeted therapeutics. In the pursuit of exploring inhibitors that specifically target the FGFR signaling pathways, a multitude of kinase inhibitors targeting FGFR has been assiduously engineered to address the heterogeneous landscape of human malignancies. This review offers an exhaustive exploration of aberrations within the FGFR pathway and their functional implications in breast cancer. Additionally, we delve into cutting-edge therapeutic approaches for the treatment of breast cancer patients bearing FGFR alterations and the management of toxicity associated with FGFR inhibitors. Furthermore, our contemplation of the evolution of cutting-edge FGFR inhibitors foresees their potential to spearhead innovative therapeutic approaches in the ongoing combat against cancer.

Molecular Targeting of the Fibroblast Growth Factor Receptor Pathway across Various Cancers

Fibroblast growth factor receptors (FGFRs) are a family of receptor tyrosine kinases that are involved in the regulation of cell proliferation, survival, and development. FGFR alterations including amplifications, fusions, rearrangements, and mutations can result in the downstream activation of tyrosine kinases, leading to tumor development. Targeting these FGFR alterations has shown to be effective in treating cholangiocarcinoma, urothelial carcinoma, and myeloid/lymphoid neoplasms, and there are currently four FGFR inhibitors approved by the Food and Drug Administration (FDA). There have been developments in multiple agents targeting the FGFR pathway, including selective FGFR inhibitors, ligand traps, monoclonal antibodies, and antibody-drug conjugates. However, most of these agents have variable and low responses, with some intolerable toxicities and acquired resistances. This review will summarize previous clinical experiences and current developments in agents targeting the FGFR pathway, and will also discuss future directions for FGFR-targeting agents.

Efficacy of futibatinib, an irreversible fibroblast growth factor receptor inhibitor, in FGFR-altered breast cancer

Several alterations in fibroblast growth factor receptor (FGFR) genes have been found in breast cancer; however, they have not been well characterized as therapeutic targets. Futibatinib (TAS-120; Taiho) is a novel, selective, pan-FGFR inhibitor that inhibits FGFR1-4 at nanomolar concentrations. We sought to determine futibatinib's efficacy in breast cancer models. Nine breast cancer patient-derived xenografts (PDXs) with various FGFR1-4 alterations and expression levels were treated with futibatinib. Antitumor efficacy was evaluated by change in tumor volume and time to tumor doubling. Alterations indicating sensitization to futibatinib in vivo were further characterized in vitro. FGFR gene expression between patient tumors and matching PDXs was significantly correlated; however, overall PDXs had higher FGFR3-4 expression. Futibatinib inhibited tumor growth in 3 of 9 PDXs, with tumor stabilization in an FGFR2-amplified model and prolonged regression (> 110 days) in an FGFR2 Y375C mutant/amplified model. FGFR2 overexpression and, to a greater extent, FGFR2 Y375C expression in MCF10A cells enhanced cell growth and sensitivity to futibatinib. Per institutional and public databases, FGFR2 mutations and amplifications had a population frequency of 1.1%-2.6% and 1.5%-2.5%, respectively, in breast cancer patients. FGFR2 alterations in breast cancer may represent infrequent but highly promising targets for futibatinib.

FGFR families: biological functions and therapeutic interventions in tumors

There are five fibroblast growth factor receptors (FGFRs), namely, FGFR1-FGFR5. When FGFR binds to its ligand, namely, fibroblast growth factor (FGF), it dimerizes and autophosphorylates, thereby activating several key downstream pathways that play an important role in normal physiology, such as the Ras/Raf/mitogen-activated protein kinase kinase/extracellular signal-regulated kinase, phosphoinositide 3-kinase (PI3K)/AKT, phospholipase C gamma/diacylglycerol/protein kinase c, and signal transducer and activator of transcription pathways. Furthermore, as an oncogene, FGFR genetic alterations were found in 7.1% of tumors, and these alterations include gene amplification, gene mutations, gene fusions or rearrangements. Therefore, FGFR amplification, mutations, rearrangements, or fusions are considered as potential biomarkers of FGFR therapeutic response for tyrosine kinase inhibitors (TKIs). However, it is worth noting that with increased use, resistance to TKIs inevitably develops, such as the well-known gatekeeper mutations. Thus, overcoming the development of drug resistance becomes a serious problem. This review mainly outlines the FGFR family functions, related pathways, and therapeutic agents in tumors with the aim of obtaining better outcomes for cancer patients with FGFR changes. The information provided in this review may provide additional therapeutic ideas for tumor patients with FGFR abnormalities.

SGLT1 as an adverse prognostic factor in invasive ductal carcinoma of the breast

PURPOSE

Sodium/glucose cotransporter (SGLT) 1 and 2 expression in carcinoma cells was recently examined, but their association with the clinicopathological factors of the patients and their biological effects on breast carcinoma cells have remained remain virtually unknown. Therefore, in this study, we explored the expression status of SGLT1 and SGLT2 in breast cancer patients and examined the effects of SGLT1 inhibitors on breast carcinoma cells in vitro.

METHODS

SGLT1 and SGLT2 were immunolocalized and we first correlated the findings with clinicopathological factors of the patients. We then administered mizagliflozin and KGA-2727, SGLT1 specific inhibitors to MCF-7 and MDA-MB-468 breast carcinoma cell lines, and their growth-inhibitory effects were examined. Protein arrays were then used to further explore their effects on the growth factors.

RESULTS

The SGLT1 high group had significantly worse clinical outcome including both overall survival and disease-free survival than low group. SGLT2 status was not significantly correlated with clinical outcome of the patients. Both mizagliflozin and KGA-2727 inhibited the growth of breast cancer cell lines. Of particular interest, mizagliflozin inhibited the proliferation of MCF-7 cells, even under very low glucose conditions. Mizagliflozin downregulated vascular endothelial growth factor receptor 2 phosphorylation.

CONCLUSION

High SGLT1 expression turned out as an adverse clinical prognostic factor in breast cancer patient. This is the first study demonstrating that SGLT1 inhibitors suppressed breast carcinoma cell proliferation. These results indicated that SGLT1 inhibitors could be used as therapeutic agents for breast cancer patients with aggressive biological behaviors.

Emerging systemic therapy options beyond CDK4/6 inhibitors for hormone receptor-positive HER2-negative advanced breast cancer

Endocrine therapy (ET) with cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) is currently the standard first-line treatment for most patients with hormone receptor (HR) positive, human epidermal growth factor receptor (HER2) negative advanced breast cancer. However, resistance to ET and CDK4/6i inevitably ensues. The optimal post-progression treatment regimens and their sequencing continue to evolve in the rapidly changing treatment landscape. In this review, we summarize the mechanisms of resistance to ET and CDK4/6i, which can be broadly classified as alterations affecting cell cycle mediators and activation of alternative signaling pathways. Recent clinical trials have been directed at the targets and pathways implicated, including estrogen and androgen receptors, PI3K/AKT/mTOR and MAPK pathways, tyrosine kinase receptors such as FGFR and HER2, homologous recombination repair pathway, other components of the cell cycle and cell death. We describe the findings from these clinical trials using small molecule inhibitors, antibody-drug conjugates and immunotherapy, providing insights into how these novel strategies may circumvent treatment resistance, and discuss how some have not translated into clinical benefit. The challenges posed by tumor heterogeneity, adaptive rewiring of signaling pathways and dose-limiting toxicities underscore the need to elucidate the latest tumor biology in each patient, and develop treatments with improved therapeutic index in the era of precision medicine.

Genomic Alterations Associated with Estrogen Receptor Pathway Activity in Metastatic Breast Cancer Have a Differential Impact on Downstream ER Signaling

Mutations in the estrogen receptor gene (ESR1), its transcriptional regulators, and the mitogen-activated protein kinase (MAPK) pathway are enriched in patients with endocrine-resistant metastatic breast cancer (MBC). Here, we integrated whole genome sequencing with RNA sequencing data from the same samples of 101 ER-positive/HER2-negative MBC patients who underwent a tumor biopsy prior to the start of a new line of treatment for MBC (CPCT-02 study, NCT01855477) to analyze the downstream effects of DNA alterations previously linked to endocrine resistance, thereby gaining a better understanding of the associated mechanisms. Hierarchical clustering was performed using expression of ESR1 target genes. Genomic alterations at the DNA level, gene expression levels, and last administered therapy were compared between the identified clusters. Hierarchical clustering revealed two distinct clusters, one of which was characterized by increased expression of ESR1 and its target genes. Samples in this cluster were significantly enriched for mutations in ESR1 and amplifications in FGFR1 and TSPYL. Patients in the other cluster showed relatively lower expression levels of ESR1 and its target genes, comparable to ER-negative samples, and more often received endocrine therapy as their last treatment before biopsy. Genes in the MAPK-pathway, including NF1, and ESR1 transcriptional regulators were evenly distributed. In conclusion, RNA sequencing identified a subgroup of patients with clear expression of ESR1 and its downstream targets, probably still benefiting from ER-targeting agents. The lower ER expression in the other subgroup might be partially explained by ER activity still being blocked by recently administered endocrine treatment, indicating that biopsy timing relative to endocrine treatment needs to be considered when interpreting transcriptomic data.

A Concise Review on Natural Products and Their Derivatives for Breast Cancer Treatment

Cancer is a leading cause of death worldwide. Among other cancers, breast cancer has been found to produce maximum number of cases in 2020. Different factors including geographical, genetic, hormonal, oral contraceptives and modern lifestyle could be responsible for the development of breast cancer and different pathways can be targeted for breast cancer treatment. The various conventional approaches used for the treatment of breast cancer including radiotherapy, chemotherapy, hormone and immunotherapy. But due to the side effects associated with these conventional treatments such as non-selectivity, multidrug resistance and bioavailability, there is a need for the development of better therapeutic agents for breast cancer treatment. Several natural products have been explored for breast cancer treatment. However, many of these natural products suffered from the limitations of poor water solubility and possess toxic side effects. To overcome these limitations, several structural analogs of natural products have been synthesized and possess potent anti-breast cancer effects with less side effects over their precursor molecules. In the present manuscript, we describe the pathogenesis of breast cancer, some potent natural products used in the treatment of breast cancer and their selected structural analogs possessing potent anti-breast cancer effects. Database such as Science direct, Pubmed and Google scholar were searched using keywords 'risk factors', 'screening methods','receptors', and 'natural products and derivatives', Registered clinical trials on selected natural products were also analyzed. Present study concludes that eight selected natural products and their derivatives possess wide potential to exhibit anti-breast cancer effects and could be explored further to develop better chemotherapeutic agents against breast cancer.

FGFR1 Antibody Validation and Characterization of FGFR1 Protein Expression in ER+ Breast Cancer

Clinical trials in patients with ER+ breast cancer with or without FGFR pathway somatic alterations have shown limited clinical benefit from treatment with FGFR tyrosine kinase inhibitors alone or in combination with endocrine therapy. This is likely because of an inadequate predictive biomarker to select appropriate patients. In this study, we evaluated 4 anti-FGFR1 antibodies in breast cancer cell lines and patient-derived xenografts with FGFR1 amplification. We correlated D8E4 expression in 209 tumors from postmenopausal patients with stage I-III operable ER+ breast cancer with FGFR1 amplification status as determined by fluorescence in situ hybridization. FGFR1 amplification was identified in 10% of tumors (21/209), 80% of which exhibited membranous FGFR1 expression; however, only 50% of amplified cases showed strong, complete membranous staining (3+) based on established criteria to score HER2 by immunohistochemistry. These findings suggest the combined evaluation of FGFR1 status by immunohistochemistry and fluorescence in situ hybridization may need to be incorporated into the selection of patients for trials with FGFR inhibitors.

Review of potential medical treatments for middle ear cholesteatoma

Middle ear cholesteatoma (MEC), is a destructive, and locally invasive lesion in the middle ear driven by inflammation with an annual incidence of 10 per 100,000. Surgical extraction/excision remains the only treatment strategy available and recurrence is high (up to 40%), therefore developing the first pharmaceutical treatments for MEC is desperately required. This review was targeted at connecting the dysregulated inflammatory network of MEC to pathogenesis and identification of pharmaceutical targets. We summarized the numerous basic research endeavors undertaken over the last 30+ years to identify the key targets in the dysregulated inflammatory pathways and judged the level of evidence for a given target if it was generated by in vitro, in vivo or clinical experiments. MEC pathogenesis was found to be connected to cytokines characteristic for Th1, Th17 and M1 cells. In addition, we found that the inflammation created damage associated molecular patterns (DAMPs), which further promoted inflammation. Similar positive feedback loops have already been described for other Th1/Th17 driven inflammatory diseases (arthritis, Crohn’s disease or multiple sclerosis). A wide-ranging search for molecular targeted therapies (MTT) led to the discovery of over a hundred clinically approved drugs already applied in precision medicine. Based on exclusion criteria designed to enable fast translation as well as efficacy, we condensed the numerous MTTs down to 13 top drugs. The review should serve as groundwork for the primary goal, which is to provide potential pharmaceutical therapies to MEC patients for the first time in history.

Gene signature and connectivity mapping to assist with drug prediction for pancreatic ductal adenocarcinoma

INTRODUCTION

The prognosis of patients with pancreatic ductal adenocarcinoma (PDAC) is highly variable and there is a paucity of effective treatment options for patients with PDAC. Genome-wide analyses may allow for potential drugs to be identified using differentially expressed genes, as well as constructing protein interaction networks and molecule-gene connectivity mapping.

METHODS

Microarray data of RNA expression profiling of PDAC and normal pancreas tissues were downloaded from the Gene Expression Omnibus (GEO). Functional and pathway enrichment information of the DEGs was obtained using the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes databases. Corresponding homologous proteins were analyzed by protein-protein interaction analysis. Survival-related hub genes were screened and potential therapeutic drugs for PDAC were identified using the connectivity mapping (cMap).

RESULTS

Of 18,229 PDAC genes assessed using RNA expression profiling from 118 PDAC tumor samples and 13 normal pancreatic tissue samples, 1502 and 744 genes were upregulated and downregulated, respectively, versus normal pancreas tissue. Protein-protein interaction analysis revealed 10 upregulated hub genes (ITGB1, ITGAV, SDC1, KRAS, CCNB2, COL1A2, AURKA, CDC20, COL1A1, COL3A1) and 10 downregulated hub genes (CPB1, CPA1, CPA2, CTRB2, CTRC, CELA3A, CELA2B, PRSS3, CELA2A, REG1A). The connectivity mapping score related to this hub gene list was used to generate the candidate drugs for PDAC treatment, which includes tyrosine kinase inhibitors (lucitanib, lapatinib, ceritinib and CYT-387), serine/threonine protein kinase inhibitors (roscovitine, BS-181, purvalanol-a, MK-2206 and palomid-529) and other small molecules.

CONCLUSION

Using available genetic atlas data, potential drug candidates for treatment of PDAC were identified based on differentially expressed genes, protein interaction analysis and connectivity mapping. These results may help focus efforts on identifying targeted agents with potential therapeutic efficacy for evaluation in prospective clinical trials of patients with PDAC.

Population Pharmacokinetic Modeling of Lucitanib in Patients with Advanced Cancer

Background

Lucitanib is an oral, potent, selective inhibitor of the tyrosine kinase activity of vascular endothelial growth factor receptors 1‒3, fibroblast growth factor receptors 1‒3, and platelet-derived growth factor receptors alpha/beta.

Objective

We aimed to develop a population pharmacokinetics (PopPK) model for lucitanib in patients with advanced cancers.

Methods

PopPK analyses were based on intensive and sparse oral pharmacokinetic data from 5 phase 1/2 clinical studies of lucitanib in a total of 403 patients with advanced cancers. Lucitanib was administered at 5‒30 mg daily doses as 1 of 2 immediate-release oral formulations: a film-coated tablet or a hard gelatin capsule.

Results

Lucitanib pharmacokinetics were best described by a 2-compartment model with zero-order release into the dosing compartment, followed by first-order absorption and first-order elimination. Large between-subject pharmacokinetic variability was partially explained by body weight. No effects of demographics or tumor type on lucitanib pharmacokinetics were observed. The model suggested that the formulation impacted release duration (tablet, 0.243 h; capsule, 0.814 h), but the effect was not considered clinically meaningful. No statistically significant effects were detected for concomitant cytochrome P450 (CYP) 3A4 inhibitors or inducers, CYP2C8 or P-glycoprotein inhibitors, serum albumin, mild/moderate renal impairment, or mild hepatic impairment. Concomitant proton pump inhibitors had no clinically significant effect on lucitanib absorption.

Conclusions

The PopPK model adequately described lucitanib pharmacokinetics. High between-subject pharmacokinetic variability supports a safety-based dose-titration strategy currently being used in an ongoing clinical study of lucitanib to optimize drug exposure and clinical benefit.

Trial Registration

ClinicalTrials.gov Identifier: NCT01283945, NCT02053636, ISRCTN23201971, NCT02202746, NCT02109016.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13318-022-00773-w.

New [1,2,4]triazolo[4,3-c]quinazoline derivatives as vascular endothelial growth factor receptor-2 inhibitors and apoptosis inducers: Design, synthesis, docking, and antiproliferative evaluation

In continuation of our previous efforts in the field of design and synthesis of vascular endothelial growth factor receptor (VEGFR)-2 inhibitors, a new series of [1,2,4]triazolo[4,3-c]quinazoline derivatives were designed and synthesized as modified analogs of some reported VEGFR-2 inhibitors. The synthesized compounds were designed to have the essential pharmacophoric features of VEGFR-2 inhibitors. Antiproliferative activities of the synthesized compounds were investigated against two tumor cell lines (HepG2 and HCT-116) using sorafenib as a positive control. Compound 10k emerged as the most promising antiproliferative agent with IC₅₀ values of 4.88 and 5.21 µM against HepG2 and HCT-116 cells, respectively. Also, it showed the highest inhibitory activity against VEGFR-2 with an IC₅₀ value of 53.81 nM compared to sorafenib (IC₅₀  = 44.34 nM). Cell cycle analysis revealed that compound 10k can arrest HepG2 cells at both the S and G2/M phases. In addition, this compound produced a tenfold increase in apoptotic cells compared to the control. Furthermore, the effect of compound 10k on the expression level of BAX, Bcl-2, and caspase-3 was assessed. This compound caused a 3.35-fold increase in BAX expression levels and a 1.25-fold reduction in Bcl-2 expression levels. The BAX/Bcl-2 ratio was calculated to be 4.57, indicating a promising apoptotic effect. It also showed a significant increase in the level of caspase-3 (4.12-fold) compared to the control cells. In silico docking, absorption, distribution, metabolism, excretion, and toxicity, and toxicity studies were performed for the synthesized compounds to investigate their binding patterns against the proposed biological target (VEGFR-2) and to assess the drug-likeness characters.

Recent progress on vascular endothelial growth factor receptor inhibitors with dual targeting capabilities for tumor therapy

Vascular endothelial growth factor receptors (VEGFRs) are a family of receptor protein tyrosine kinases that play an important role in the regulation of tumor-induced angiogenesis. Currently, VEGFR inhibitors have been widely used in the treatment of various tumors. However, current VEGFR inhibitors are limited to a certain extent due to limited clinical efficacy and potential toxicity, which hinder their clinical application. Thus, the development of new strategies to improve the clinical outcomes and minimize the toxic effects of VEGFR inhibitors is required. Given the synergistic effect of VEGFR and other therapies in tumor development and progression, VEGFR dual-target inhibitors are becoming an attractive approach due to their favorable pharmacodynamics, low toxicity, and anti-resistant effects. This perspective provides an overview of the development of VEGFR dual-target inhibitors from multiple aspects, including rational target combinations, drug discovery strategies, structure–activity relationships and future directions.

The Multi-Kinase Inhibitor Lucitanib Enhances the Antitumor Activity of Coinhibitory and Costimulatory Immune Pathway Modulators in Syngeneic Models

Lucitanib is a multi-tyrosine kinase inhibitor whose targets are associated with angiogenesis and other key cancer and immune pathways. Its antiangiogenic properties are understood, but lucitanib's immunomodulatory activity is heretofore unknown. Lucitanib exhibited such activity in vivo, increasing CD3+, CD8+, and CD4+ T cells and decreasing dendritic cells and monocyte-derived suppressor cells in mouse spleens. Depletion of CD8+ T cells from syngeneic MC38 colon tumor-bearing mice reduced the antitumor efficacy of lucitanib and revealed a CD8+ T-cell-dependent component of lucitanib's activity. The combination of lucitanib and costimulatory immune pathway agonists targeting 4-1BB, glucocorticoid-induced TNFR (GITR), inducible T-cell co-stimulator (ICOS), or OX40 exhibited enhanced antitumor activity compared with each single agent in immunocompetent tumor models. Lucitanib combined with blockade of cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) or programmed cell death protein-1 (PD-1) coinhibitory immune pathways also showed enhanced antitumor activity over the single agents in multiple models. In CT26 tumors, lucitanib, alone or combined with anti-PD-1, reduced CD31+ vessels and depleted F4/80+ macrophages. Combination treatment also increased the number of intratumoral T cells. Gene expression in pathways associated with immune activity was upregulated by lucitanib in MC38 tumors and further potentiated by combination with anti-PD-1. Accordingly, lucitanib, alone or combined with anti-PD-1, increased intratumoral CD8+ T-cell abundance. Lucitanib's antitumor and pharmacodynamic activity, alone or combined with anti-PD-1, was not recapitulated by specific vascular endothelial growth factor receptor-2 (VEGFR2) inhibition. These data indicate that lucitanib can modulate vascular and immune components of the tumor microenvironment and cooperate with immunotherapy to enhance antitumor efficacy. They support the clinical development of lucitanib combined with immune pathway modulators to treat cancer.

The applications of plasma cell-free DNA in cancer detection: Implications in the management of breast cancer patients

Liquid biopsy probes DNA, RNA, and proteins in body fluids for cancer detection and is one of the most rapidly developing areas in oncology. Tumor-derived DNA (circulating tumor DNA, ctDNA) in the context of cell-free DNA (cfDNA) in blood has been the main target for its potential utilities in cancer detection. Liquid biopsy can report tumor burden in real-time without invasive interventions, and would be feasible for screening tumor types that lack standard-of-care screening approaches. Two major approaches to interrogating ctDNA are genetic mutation and DNA methylation profiling. Mutation profiling can identify tumor driver mutations and guide precision therapy. Targeted genomic profiling of DNA methylation has become the main approach for cancer screening in the general population. Here we review the recent technological development and ongoing efforts in clinical applications. For clinical applications, we focus on breast cancer, in which subtype-specific biology demarcates the applications of ctDNA.

Results of the phase IIa RADICAL trial of the FGFR inhibitor AZD4547 in endocrine resistant breast cancer

We conducted a phase IIa, multi-centre, open label, single arm study (RADICAL; NCT01791985) of AZD4547 (a potent and selective inhibitor of Fibroblast Growth Factor Receptor (FGFR)-1, 2 and 3 receptor tyrosine kinases) administered with anastrozole or letrozole in estrogen receptor positive metastatic breast cancer patients who had become resistant to aromatase inhibitors. After a safety run-in study to assess safety and tolerability, we recruited 52 patients. The primary endpoint was change in tumour size at 12 weeks, and secondary endpoints were to assess response at 6 weeks, 20 weeks and every 8 weeks thereafter and tolerability of the combined treatment. Two partial responses (PR) and 19 stable disease (SD) patients were observed at the 12-week time point. At 28 weeks, according to centrally reviewed Response Evaluation Criteria in Solid Tumours (RECIST) criteria, five PR and 8 SD patients were observed in 50 assessable cases. Overall, objective response rate (5 PR) was of 10%, meeting the pre-specified endpoint. Fourteen patients discontinued due to adverse events. Eleven patients had retinal pigment epithelial detachments which was asymptomatic and reversible in all but one patient. Exploratory ribonucleic acid sequencing (RNA-Seq) analysis was done on patients' samples: 6 differentially-expressed-genes could distinguish those who benefited from the addition of AZD4547.

Serial Tumor Molecular Profiling of Newly Diagnosed HER2-Negative Breast Cancers During Chemotherapy in Combination with Angiogenesis Inhibitors

Background

Breast cancers are heterogeneous with variable clinical courses and treatment responses.

Objective

We sought to evaluate dynamic changes in the molecular landscape of HER2-negative tumors treated with chemotherapy and anti-angiogenic agents.

Patients and Methods

Newly diagnosed HER2-negative breast cancer patients received low-dose sunitinib or bevacizumab prior to four 2-weekly cycles of dose-dense doxorubicin and cyclophosphamide. Tumor biopsies were obtained at baseline, after 2 weeks and after 8 weeks of chemotherapy. Next-generation sequencing was performed to assess for single nucleotide variants (SNVs) and copy number alterations (CNAs) of 440 cancer-related genes (ACTOnco^®). Observed genomic changes were correlated with the Miller-Payne histological response to treatment.

Results

Thirty-four patients received sunitinib and 18 received bevacizumab. In total, 77% were hormone receptor positive (HER2−/HR+) and 23% were triple negative breast cancers (TNBC). New therapy-induced mutations were infrequent, occurring only in 13%, and appeared early after a single cycle of treatment. Seventy-two percent developed changes in the variant allele frequency (VAF) of pathogenic SNVs; the majority (51%) of these changes occurred early at 2 weeks and were sustained for 8 weeks. Changes in VAF of SNVs were most commonly seen in the PI3K/mTOR/AKT pathway; 13% developed changes in pathogenic mutations, which potentially confer sensitivity to PIK3CA inhibitors. Tumors with poor Miller-Payne response to treatment were less likely to experience changes in VAF of SNVs compared with those with good response (50% [7/14] vs 15% [4/24] had no changes observed at any timepoint, p = 0.029).

Conclusions

Serial molecular profiling identifies early therapy-induced genomic alterations, which may guide future selection of targeted therapies in breast cancer patients who progress after standard chemotherapy.

Clinical trial registration

ClinicalTrials.gov: NCT02790580 (first posted June 6, 2016).

Supplementary Information

The online version contains supplementary material available at 10.1007/s11523-022-00886-x.

Evolution of surgical treatment of metastatic spine tumors

PURPOSE

The treatment of cancer has transformed over the past 40 years, with medical oncologists, radiation oncologists and surgeons working together to prolong survival times and minimize treatment related morbidity. With each advancement, the risk-benefit scale has been calibrated to provide an accurate assessment of surgical hazard. The goal of this review is to look back at how the role of surgery has evolved with each new medical advance, and to explore the role of surgeons in the future of cancer care.

METHODS

A literature review was conducted, highlighting the key papers guiding surgical management of spinal metastatic lesions.

CONCLUSION

The roles of surgery, medical therapy, and radiation have evolved over the past 40 years, with new advances requiring complex multidisciplinary care.

New Insights in the Interaction of FGF/FGFR and Steroid Receptor Signaling in Breast Cancer

Luminal breast cancer (BrCa) has a favorable prognosis compared with other tumor subtypes. However, with time, tumors may evolve and lead to disease progression; thus, there is a great interest in unraveling the mechanisms that drive tumor metastasis and endocrine resistance. In this review, we focus on one of the many pathways that have been involved in tumor progression, the fibroblast growth factor/fibroblast growth factor receptor (FGFR) axis. We emphasize in data obtained from in vivo experimental models that we believe that in luminal BrCa, tumor growth relies in a crosstalk with the stromal tissue. We revisited the studies that illustrate the interaction between hormone receptors and FGFR. We also highlight the most frequent alterations found in BrCa cell lines and provide a short review on the trials that use FGFR inhibitors in combination with endocrine therapies. Analysis of these data suggests there are many players involved in this pathway that might be also targeted to decrease FGF signaling, in addition to specific FGFR inhibitors that may be exploited to increase their efficacy.

FGFR1 Amplification and Response to Neoadjuvant Anti-HER2 Treatment in Early HER2-Positive Breast Cancer

HER2-positive breast cancer (BC) is an aggressive subtype that affects 20–25% of BC patients. For these patients, neoadjuvant therapy is a good option that targets a pathological complete response (pCR) and more breast-conserving surgery. In effect, the outcomes of patients with HER2-positive BC have dramatically improved since the introduction of anti-HER2 antibodies such as trastuzumab (TZ) and/or pertuzumab (PZ) added to chemotherapy. This study sought to examine whether correlation exists between copy number variations (CNVs) in several genes related to the PI3K/AKT pathway (HER2, FGFR1, PIK3CA, AKT3 and MDM2) and the efficacy of anti-HER2 neoadjuvant treatment in patients with early HER2-positive BC. Forty-nine patients received TZ or PZ/TZ and chemotherapy as neoadjuvant treatment. Gene CNVs were determined by quantitative polymerase chain reaction on paraffin-embedded biopsy specimens. The response to 6 months of therapy was assessed by Miller–Payne grading of the tumor on surgical resection; grades 4 and 5, indicating >90% tumor reduction, were defined as a good response. A good response was shown by 64.5% and a pCR by 31.2% of patients. When stratified by anti-HER2 antibody received and gene CNV, it was found that patients with FGFR1 gene amplification or those with FGFR1 amplification treated with TZ alone showed a poor response (p = 0.024 and p = 0.037, respectively). In the subset of patients treated with TZ/PZ combined, the pCR rate was significantly lower among those showing FGFR1 amplification (p = 0.021). Although based on a small sample size, our findings suggest that patients with FGFR1 amplification might benefit less from anti-HER2 antibody therapy.

FGFR signaling and endocrine resistance in breast cancer: Challenges for the clinical development of FGFR inhibitors

Fibroblast growth factors (FGFs) and their receptors (FGFRs) have been extensively investigated in solid malignancies, representing an attractive therapeutic target. In breast cancer, especially in estrogen receptor positive (ER+) subtype, FGFR signaling aberrations have been reported to contribute to proliferation, dedifferentiation, metastasis and drug resistance. However, clinical trials evaluating the use of FGFR inhibitors in breast cancer have had disappointing results. The different biological properties of distinct FGFR alterations and lack of established patient selection criteria, in addition to the early use of non-selective inhibitors, are possible reasons of this failure. Herein, we review the current knowledge regarding the role of FGFR signaling in endocrine resistance in breast cancer. We will also summarize the results from the clinical development of FGFR inhibitors in breast cancer, discussing future challenges to identify the correct cohorts of patients to enroll in trials testing FGFR inhibitors.

High FGFR1-4 mRNA expression levels correlate with response to selective FGFR inhibitors in breast cancer

PURPOSE

FGFR1 amplification (FGFR1amp) is recurrent in metastatic breast cancer (BC) and is associated with resistance to endocrine therapy (ET) and CDK4/6 inhibitors (CDK4/6i). Multi-tyrosine kinase inhibitors (MTKI) and selective pan-FGFR inhibitors (FGFRi) are being developed for FGFR1amp BC. High-level FGFR amplification and protein expression by IHC have identified BC responders to FGFRi or MTKI, respectively.

EXPERIMENTAL DESIGN

Here, we used preclinical models and patient samples to identify predictive biomarkers to these drugs. We evaluated the antitumor activity of an FGFRi and an MTKI in a collection of seventeen BC patient-derived xenografts (PDXs) harboring amplification in FGFR1/2/3/4 and in ten patients receiving either an FGFRi/MTKI. mRNA levels were measured on FFPE tumor samples using two commercial strategies. Proliferation and angiogenesis were evaluated by detecting Ki-67 and CD31 in viable areas by immunofluorescence.

RESULTS

High FGFR1-4 mRNA levels but not copy number alteration (CNA) associated with FGFRi response. Treatment with MTKI showed higher response rates than with FGFRi (86% vs 53%), regardless of the FGFR1-4 mRNA levels. FGFR-addicted PDXs exhibited an antiproliferative response to either FGFRi or MTKI, and PDXs exclusively sensitive to MTKI exhibited an additional anti-angiogenic response. Consistently, clinical benefit of MTKI was not associated with high FGFR1-4 mRNA levels and it was observed in patients previously treated with anti-angiogenic drugs.

CONCLUSION

Tailored therapy with FGFRi in molecularly-selected metastatic BC based on high FGFR1-4 mRNA levels warrants prospective validation in luminal BC CDK4/6i-resistant patients and in TNBC patients without targeted therapeutic options.

Combined endocrine and targeted therapy in luminal breast cancer

Introduction: For decades, endocrine therapy has been the cornerstone of management for luminal breast cancer. Despite the substantial benefit derived by patients from endocrine therapy, primary and secondary resistances to endocrine therapy are serious clinical issues.Areas covered: Today, in the advanced setting, three distinct classes of targeted agents mTOR, CDK 4/6, and PI3K inhibitors, are approved for use. CDK 4/6 inhibitors have improved outcomes substantially, changing the natural history of advanced luminal breast cancer. Current studies seek to bring CDK 4/6 inhibitors to the early setting. This review will cover all available data on target therapy combinations with endocrine therapy for both the early and advanced settings, including approved drugs and agents in development.Expert opinion: Combined endocrine and target therapy has changed the landscape in advanced disease. In early disease, it is possible to have a large impact, particularly in patients with higher risk of relapse. Trials like ADAPTCYCLE seek to leverage neoadjuvant data to de-escalate treatment, substituting chemotherapy for CDK 4/6 inhibitors. In advanced diseases, studies such as PADA-1 point toward a future in which ctDNA will be used to define management before clinical progression occurs.

TNBC: Potential Targeting of Multiple Receptors for a Therapeutic Breakthrough, Nanomedicine, and Immunotherapy

Triple-negative breast cancer (TNBC) is a heterogeneous, recurring cancer associated with a high rate of metastasis, poor prognosis, and lack of therapeutic targets. Although target-based therapeutic options are approved for other cancers, only limited therapeutic options are available for TNBC. Cell signaling and receptor-specific targets are reportedly effective in patients with TNBC under specific clinical conditions. However, most of these cancers are unresponsive, and there is a requirement for more effective treatment modalities. Further, there is a lack of effective biomarkers that can distinguish TNBC from other BC subtypes. ER, PR, and HER2 help identify TNBC and are widely used to identify patients who are most likely to respond to diverse therapeutic strategies. In this review, we discuss the possible treatment options for TNBC based on its inherent subtype receptors and pathways, such as p53 signaling, AKT signaling, cell cycle regulation, DNA damage, and programmed cell death, which play essential roles at multiple stages of TNBC development. We focus on poly-ADP ribose polymerase 1, androgen receptor, vascular endothelial growth factor receptor, and epidermal growth factor receptor as well as the application of nanomedicine and immunotherapy in TNBC and discuss their potential applications in drug development for TNBC.

Novel Regulatory Factors and Small-Molecule Inhibitors of FGFR4 in Cancer

Fibroblast growth factor receptor 4 (FGFR4) is a tyrosine kinase receptor that is a member of the fibroblast growth factor receptor family and is stimulated by highly regulated ligand binding. Excessive expression of the receptor and its ligand, especially FGF19, occurs in many types of cancer. Abnormal FGFR4 production explains these cancer formations, and therefore, this receptor has emerged as a potential target for inhibiting cancer development. This review discusses the diverse mechanisms of oncogenic activation of FGFR4 and highlights some currently available inhibitors targeting FGFR4.

Inhibition of FGF-FGFR and VEGF-VEGFR signalling in cancer treatment

The sites of targeted therapy are limited and need to be expanded. The FGF‐FGFR signalling plays pivotal roles in the oncogenic process, and FGF/FGFR inhibitors are a promising method to treat FGFR‐altered tumours. The VEGF‐VEGFR signalling is the most crucial pathway to induce angiogenesis, and inhibiting this cascade has already got success in treating tumours. While both their efficacy and antitumour spectrum are limited, combining FGF/FGFR inhibitors with VEGF/VEGFR inhibitors are an excellent way to optimize the curative effect and expand the antitumour range because their combination can target both tumour cells and the tumour microenvironment. In addition, biomarkers need to be developed to predict the efficacy, and combination with immune checkpoint inhibitors is a promising direction in the future. The article will discuss the FGF‐FGFR signalling pathway, the VEGF‐VEGFR signalling pathway, the rationale of combining these two signalling pathways and recent small‐molecule FGFR/VEGFR inhibitors based on clinical trials.

Targeting Drugs Against Fibroblast Growth Factor(s)-Induced Cell Signaling

BACKGROUND

The fibroblast growth factor (FGF) family is comprised of 23 highly regulated monomeric proteins that regulate a plethora of developmental and pathophysiological processes, including tissue repair, wound healing, angiogenesis, and embryonic development. Binding of FGF to fibroblast growth factor receptor (FGFR), a tyrosine kinase receptor, is facilitated by a glycosaminoglycan, heparin. Activated FGFRs phosphorylate the tyrosine kinase residues that mediate induction of downstream signaling pathways, such as RAS-MAPK, PI3K-AKT, PLCγ, and STAT. Dysregulation of the FGF/FGFR signaling occurs frequently in cancer due to gene amplification, FGF activating mutations, chromosomal rearrangements, integration, and oncogenic fusions. Aberrant FGFR signaling also affects organogenesis, embryonic development, tissue homeostasis, and has been associated with cell proliferation, angiogenesis, cancer, and other pathophysiological changes.

OBJECTIVE

This comprehensive review will discuss the biology, chemistry, and functions of FGFs, and its current applications toward wound healing, diabetes, repair and regeneration of tissues, and fatty liver diseases. In addition, specific aberrations in FGFR signaling and drugs that target FGFR and aid in mitigating various disorders, such as cancer, are also discussed in detail.

CONCLUSION

Inhibitors of FGFR signaling are promising drugs in the treatment of several types of cancers. The clinical benefits of FGF/FGFR targeting therapies are impeded due to the activation of other RTK signaling mechanisms or due to the mutations that abolish the drug inhibitory activity on FGFR. Thus, the development of drugs with a different mechanism of action for FGF/FGFR targeting therapies is the recent focus of several preclinical and clinical studies.

Exploration of structural requirements for the inhibition of VEGFR-2 tyrosine kinase: Binding site analysis of type II, 'DFG-out' inhibitors

The conserved three-dimensional structure of receptor tyrosine kinases (RTKs) has been varyingly observed in prokaryotes to humans that actively participate in the phosphorylation process of tyrosine residues in the protein, which results in the alteration of protein's function. Mutation and transcriptional or post-translational modifications lead to a deregulation of kinases, which ultimately fallout into the development of pathological conditions like cancer. The human genome encodes two kinds of tyrosine kinases: non-receptor tyrosine kinases (NRTKs) and receptor tyrosine kinases (RTKs). Among these kinases, VEGF/VEGFR-2 signaling cascade is an important target to develop novel small-molecule inhibitors for the therapy of abnormal angiogenesis incorporated with cancer. Due to advances in the knowledge of the catalytic domain and 'DFG-motif' region, selective 'DFG-in' (type I) and 'DFG-out' (type II) VEGFR-2/KDR inhibitors were successfully developed, and some are in different phases of a clinical trial. 'DFG-out' (inactive) confirmation has significant advantages over 'DFG-in' (active) confirmation concerning the affinity of the ATP at the catalytic domain. Further, in the catalytic domain, between front and back cleft, smaller gatekeeper residue (Val916) present; therefore, selectivity against VEGFR-2 could be precisely achieved. In this review, small molecule type II/'DFG-out' inhibitors, their conformation, interaction at receptor binding pocket, and structural requirements to inhibit VEGFR-2 at the molecular level are discussed.HighlightsVEGFR-2 is a type of membrane-bound receptor tyrosine kinases (RTKs) that regulates the process of vasculogenesis and angiogenesis.Small molecule first-generation type I, 'DFG-in' and second-generation type II, 'DFG-out' VEGFR-2 inhibitors exhibit clinical benefits in the treatment of aberrant angiogenesis associated with cancer.Molecular docking of FDA approved and novel type II inhibitors were performed using X-ray crystal structures of VEGFR-2; binding site analysis was carried out.Structural requirements for the inhibition of VEGFR-2 were identified.

Resistance to cyclin-dependent kinase (CDK) 4/6 inhibitors confers cross-resistance to other CDK inhibitors but not to chemotherapeutic agents in breast cancer cells

Background

Combined endocrine therapy with a cyclin-dependent kinase (CDK) 4/6 inhibitor has been indicated to improve not only progression-free survival, but also overall survival in patients with hormone receptor (HR)-positive, HER2-negative advanced breast cancer. However, resistance to this combination therapy inevitably develops. How to manage this resistant breast cancer is one of the most important clinical issues. To investigate the mechanisms of action responsible for resistance, we developed breast cancer cells resistant to CDK4/6 inhibitors, and analyzed their biological characteristics and sensitivity to different anticancer agents.

Methods

HR-positive, HER2-negative MCF-7 and KPL-1 breast cancer cells were cultivated in palbociclib (PAL) or abemaciclib (ABE)-added culture medium for over 5 months, and we successfully developed PAL- or ABE-resistant cells. The effects of PAL or ABE on the cell growth, basal RB expression, RB phosphorylation, cell cycle and cell senescence were compared between resistant and parental cells. Effects of the other CDK4/6 inhibitor, different chemotherapeutic agents and estrogen on the cell growth were also examined. The expression levels of cyclin D1, CDK2, CDK4, CDK6, cyclin E1 and estrogen receptor (ER)-ɑ were measured using RT-PCR.

Results

Long-term exposure to up to 200 nM PAL or ABE resulted in the development of PAL- or ABE-resistant MCF-7 or KPL-1 breast cancer cells. Basal expression levels of RB in both resistant cells were down-regulated. Inhibitory effects of either PAL or ABE on RB phosphorylation were reduced in both resistant cells. Accordingly, G1-S cell cycle retardation and cell senescence induced by either inhibitor were also attenuated in both resistant cells. Both resistant cells were cross-resistant to the other CDK4/6 inhibitor but almost as equally sensitive to different chemotherapeutic agents (5-fluorouracil, gemcitabine, paclitaxel, docetaxel, doxorubicin and eribulin) as the parental cells. The mRNA expression level of CDK6 significantly increased in the resistant MCF-7 cells and that of Rb1 significantly decreased in the resistant KPL-1 cells. Although both resistant cells were less sensitive to estrogen than the parental cells, the expression levels of ER-ɑ did not significantly change in either.

Conclusions

Our study suggests that acquired resistance to PAL or ABE confers cross-resistance to the other CDK4/6 inhibitor but not to chemotherapeutic agents in HR-positive, HER2-negative breast cancer cells. Down-regulation of basal RB expression and normalized RB phosphorylation reduced by CDK4/6 inhibitors may be responsible for the attenuated anti-cell growth effects of the inhibitors.

Electronic supplementary material

The online version of this article (10.1007/s12282-020-01150-8) contains supplementary material, which is available to authorized users.

Occult metastatic thyroid cancer diagnosed during breast cancer axillary sentinel node biopsy

SUMMARY

In most developed countries, breast carcinoma is the most common malignancy in women and while thyroid cancer is less common, its incidence is almost three to five times greater in women than in men. Since 1966, studies have demonstrated an association between thyroid and breast cancer and despite these studies, the mechanism/s by which they are related, remains unclear. We present a case of a 56-year-old lady who initially presented in 2014 with a screen detected left breast carcinoma but was subsequently found to have occult metastatic thyroid cancer to the axilla, diagnosed from a sentinel node biopsy from the primary breast procedure. The patient underwent a left mastectomy, left axillary dissection and total thyroidectomy followed by three courses of radioactive iodine ablation. Despite this, her thyroglobulin level continued to increase, which was secondary to a metastatic thyroid cancer parasternal metastasis. Breast and thyroid cancer presents metachronously or synchronously more often than by chance. With improving mortality in primary cancers, such as breast and differentiated thyroid cancer, it is likely that as clinicians, we will continue to encounter this association in practice.

LEARNING POINTS

There has been a long-standing observation of an association between breast and thyroid cancer although the exact mechanism of this association remains unclear. Our patient presented with thyroid cancer with an incidental diagnosis from a sentinel node biopsy during her primary breast operation for breast cancer and was also found to have a parasternal distant bony metastasis. Thyroid axillary metastases are generally rare. The interesting nature in which this patient's metastatic thyroid carcinoma behaved more like a breast carcinoma highlights a correlation between these two cancers. With improving mortality in these primary cancers, clinicians are likely to encounter this association in clinical practice. Systemic therapy for metastatic breast and thyroid cancers differ and therefore a clear diagnosis of metastasis is crucial.

Novel targeted therapies for metastatic breast cancer

Metastatic breast cancer (mBC) continues to be a leading cause of cancer-related death in women. Even though mortality rates have improved over recent years, the 5-year survival rate of advanced BC is still at only 27%. As researchers and clinicians attempt to tackle this challenge, there has been extensive research and many trials studying treatment options for BC patients with metastatic disease, with numerous new therapies being discovered as a result. We review the most pertinent novel agents to enter the scope of BC treatment, including CDK4/6 inhibitors, PI3K inhibitors, mTOR inhibitors, immunotherapy, PARP inhibitors, and more.

Biologic therapy for advanced breast cancer: recent advances and future directions

INTRODUCTION

Advanced breast cancer (ABC) is a leading cause of mortality, morbidity, and disability in women worldwide. For decades, treatment of ABC has relied on chemotherapy and endocrine treatments (ET), until HER2 was recognized as a 'druggable' target in the 1990s. Thereafter, various anti-HER2 drugs have been approved for the HER2-positive subtype, but only in the last few years, biologic agents targeting different pathways have entered the therapeutic arsenal of luminal and triple-negative cancers.

AREAS COVERED

The purpose of the present review is to recapitulate the most promising novel biologic agents being developed for the treatment of ABC. New drugs for all breast cancer subtypes are discussed, as well as some potential future directions in ABC treatment.

EXPERT OPINION

Several biologic drugs have been recently approved, revolutionizing ABC treatment algorithms: key examples are CDK4/6-inhibitors and the PI3K-inhibitor alpelisib for endocrine-positive ABC; atezolizumab for triple-negative cancers; two PARP-inhibitors for HER2-negative germinal BRCA-mutated cancers. Additionally, multiple drugs are demonstrating activity in late-phase clinical trials for all subtypes. While some of these represent pharmacological evolutions of previously approved drugs, some others might pave the way for new paradigms in ABC, challenging both its classification and current treatment algorithms.

Breast Cancer: A Molecularly Heterogenous Disease Needing Subtype-Specific Treatments

Breast cancer is the most commonly occurring cancer in women. There were over two-million new cases in world in 2018. It is the second leading cause of death from cancer in western countries. At the molecular level, breast cancer is a heterogeneous disease, which is characterized by high genomic instability evidenced by somatic gene mutations, copy number alterations, and chromosome structural rearrangements. The genomic instability is caused by defects in DNA damage repair, transcription, DNA replication, telomere maintenance and mitotic chromosome segregation. According to molecular features, breast cancers are subdivided in subtypes, according to activation of hormone receptors (estrogen receptor and progesterone receptor), of human epidermal growth factors receptor 2 (HER2), and or BRCA mutations. In-depth analyses of the molecular features of primary and metastatic breast cancer have shown the great heterogeneity of genetic alterations and their clonal evolution during disease development. These studies have contributed to identify a repertoire of numerous disease-causing genes that are altered through different mutational processes. While early-stage breast cancer is a curable disease in about 70% of patients, advanced breast cancer is largely incurable. However, molecular studies have contributed to develop new therapeutic approaches targeting HER2, CDK4/6, PI3K, or involving poly(ADP-ribose) polymerase inhibitors for BRCA mutation carriers and immunotherapy.

Microfluidic Droplet Digital PCR Is a Powerful Tool for Detection of BRAF and TERT Mutations in Papillary Thyroid Carcinomas

We examined the utility of microfluidic digital PCR (dPCR) for detection of BRAF and TERT mutations in thyroid tumors. DNA extracted from 100 thyroid tumors (10 follicular adenomas, 10 follicular cancers, 5 medullary cancers, and 75 papillary thyroid cancer (PTC) were used for detection of BRAF and TERT mutations. Digital PCRs were performed using rare mutation SNP genotyping assays on QuantStudio 3D platform. In PTCs, BRAFV600E was detected by dPCR and Sanger sequencing in 42/75 (56%) and in 37/75 (49%), respectively. BRAFV600E was not detected in other tumors. The ratio of mutant/total BRAF alleles varied from 4.7% to 47.5%. These ratios were higher in classical PTCs (27.1%) as compared to follicular variant PTCs (9.4%) p = 0.001. In PTCs with and without metastases, the ratios of mutant/total BRAF alleles were 27.6% and 18.4%, respectively, (p = 0.03). In metastatic lesions percentages of mutant/total BRAF alleles were similar to those detected in primary tumors. TERTC228T and TERTC250T were found in two and one cases, respectively, and these tumors concomitantly harbored BRAFV600E. These tumors exhibited gross extra-thyroidal extension, metastases to lymph nodes, and pulmonary metastases (one case). Our results showed that dPCR allows quantitative assessment of druggable targets in PTCs and could be helpful in a molecular-based stratification of prognosis in patients with thyroid cancer.