Molecular Biology and Therapeutic Targets of Primitive Tracheal Tumors: Focus on Tumors Derived by Salivary Glands and Squamous Cell Carcinoma

Primary tracheal tumors are rare, constituting approximately 0.1-0.4% of malignant diseases. Squamous cell carcinoma (SCC) and adenoid cystic carcinoma (ACC) account for about two-thirds of these tumors. Despite most primary tracheal cancers being eligible for surgery and/or radiotherapy, unresectable, recurrent and metastatic tumors may require systemic treatments. Unfortunately, the poor response to available chemotherapy as well as the lack of other real therapeutic alternatives affects the quality of life and outcome of patients suffering from more advanced disease. In this condition, target therapy against driver mutations could constitute an alternative to chemotherapy, and may help in disease control. The past two decades have seen extraordinary progress in developing novel target treatment options, shifting the treatment paradigm for several cancers such as lung cancer. The improvement of knowledge regarding the genetic and biological alterations, of major primary tracheal tumors, has opened up new treatment perspectives, suggesting the possible role of biological targeted therapies for the treatment of these rare tumors. The purpose of this review is to outline the state of knowledge regarding the molecular biology, and the preliminary data on target treatments of the main primary tracheal tumors, focusing on salivary-gland-derived cancers and squamous cell carcinoma.

Mutation signatures to Pan-Cancer Atlas: Investigation of the genomic landscape of muscle-invasive bladder cancer

The Cancer Genome Atlas (TCGA) for bladder cancer was published in 2014 with updated annotation of over 400 patients with muscle-invasive bladder cancer (MIBC) in 2017. This tremendous work established the foundation of the genomic landscape of MIBC. The next steps to utilize information from The Cancer Genome Atlas is to (1) identify the causes of mutation, (2) determine the significant differences and sources of heterogeneity, and (3) apply these tools toward patient care. In this review, we discuss the full spectrum of the genomic landscape of MIBC toward the goal of therapeutic application.

Targeting FGFR in Squamous Cell Carcinoma of the Lung

Unlike for adenocarcinomas of the lung, no molecular targeted therapies have yet been developed for squamous cell lung cancers, because targetable oncogenic aberrations are scarce in this tumor type. Recent discoveries have established that the fibroblast growth factor (FGF) signaling pathway plays a fundamental role in cancer development by supporting tumor angiogenesis and cancer cell proliferation via different mechanisms. Through comprehensive genomic studies, aberrations in the FGF pathway have been identified in various tumor types, including squamous cell lung cancer, making FGF receptor (FGFR) a potentially druggable target in this malignancy. Several multi-targeted tyrosine kinase inhibitors include FGFR in their target spectrum and a number of these compounds have been approved for clinical use in different cancers. Novel agents selectively targeting FGFRs have been developed and are currently under investigation in clinical trials, showing promising results. This article reviews FGFR aberrations and the clinical data involving selective and multikinase FGFR inhibitors in squamous cell lung cancer.

Targeted Therapies Against Growth Factor Signaling in Breast Cancer

Breast cancer is the most prevalent female malignancy throughout the world. Conventional treatment strategies for breast cancer consist of chemotherapy, radiation, surgery, chemoradiation, hormone therapy, and targeted therapies. Among them, targeted therapies show advantages to reduce cost and toxicity for being possible for individualized treatments based on the intrinsic subtypes of breast cancer. With deeper understanding of key signaling pathways concerning tumor growth and survival, growth factor-controlled signaling pathways are frequently dysregulated in the development and progression of breast cancer. Thus, targeted therapies against growth factor-mediated signaling pathways have been shown to have promising efficacy in both preclinical animal models and human clinical trials. In this chapter, we will briefly introduce inhibitors and monoclonal antibodies that target the main growth factor-modulated scenarios including epidermal growth factor receptor (EGFR), transforming growth factor beta (TGF-β), insulin-like growth factor 1 receptor (IGF1R), and fibroblast growth factor receptor (FGFR) signaling pathways in breast cancer therapy.

Spectrum of genomic alterations in FGFR3: current appraisal of the potential role of FGFR3 in advanced urothelial carcinoma

Molecular analysis has identified subsets of urothelial carcinoma (UC) expressing distinct genetic signatures. Genomic alterations in the oncogenic fibroblast growth factor receptor 3 (FGFR3) pathway are among the most well described in UC and have led to extensive and ongoing investigation of FGFR3-targeted therapies in this disease, although no new drugs have yet been approved. Given the unmet need for effective treatments in advanced and metastatic UC, a better understanding of the known molecular alterations of FGFR3 and of the previous and ongoing clinical investigations of this promising target in UC deserves attention. The objective of the present review is to describe the landscape of alterations and biology of FGFR3 in UC, comprehensively summarize the current state of UC clinical trials of FGFR3 inhibitors, and discuss future therapeutic applications. Using the Pubmed and Clinicaltrials.gov databases, articles describing the spectrum and biological activity of FGFR3 genomic alterations and trials of FGFR3 inhibitors in UC were identified. Search terms included 'FGFR3 genomic alterations' and 'urothelial cancer' or 'bladder cancer'. Genomic alterations, including translocations and activating mutations, are increasingly described in advanced and metastatic UC. The majority of clinical trials have been performed in unselected populations; however, recent studies have reported encouraging preliminary data. We argue that routine use of molecular genomic tumour analysis in UC may inform selection of patients for appropriate trials and we further investigate the potential of FGFR3 as a meaningful clinical target for this difficult disease.

Muscle-invasive urothelial bladder cancer: an update on systemic therapy

Urothelial carcinoma is a common malignancy that carries a poor prognosis when the disease includes muscle invasion. Metastatic urothelial carcinoma is almost uniformly fatal. The evidence behind treatment options in the neoadjuvant, adjuvant and metastatic settings are discussed in this manuscript, with a focused review of standard and investigational cytotoxic, targeted, and immunotherapy approaches. We have focused especially on neoadjuvant cisplatin-based therapy (supported by level one evidence) and on novel immunotherapy agents such as checkpoint inhibitors, which have shown great promise in early clinical studies.

Targeting FGF19/FGFR4 Pathway: A Novel Therapeutic Strategy for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a lethal cancer with limited systemic therapeutic options. Liver carcinogenesis is a complex procedure and various pathways have been found to be deregulated which are potential targets for novel treatments. Aberrant signalling through FGF19 and its receptor FGFR4 seems to be the oncogenic driver for a subset of HCCs and is associated with poor prognosis. Inhibition of the pathway in preclinical models has shown antitumour activity and has triggered further evaluation of this strategy to in vivo models. This review aims to describe the role of the FGF19/FGFR4 pathway in hepatocellular carcinoma and its role as a potential predictive biomarker for novel targeted agents against FGF19/FGFR4 signalling.

Complexity of FGFR signalling in metastatic urothelial cancer

BACKGROUND

Urothelial cancers (UC) are the fourth most common tumours worldwide after prostate (or breast), lung and colorectal cancer. Despite recent improvements in their management, UC remain an aggressive disease associated with a poor outcome. Following disease progression on first-line platinum-based chemotherapy, very few effective treatment options are available and none of them have shown significant improvement in overall survival. Alterations of the fibroblast growth factor receptor (FGFR) pathway including amplification, mutations and overexpression are common in UC. Pre-clinical data suggest that the presence of such dysregulations may confer sensitivity to FGFR inhibitors.

MATERIALS AND METHODS

We present here the case of a patient with a metastatic UC of the renal pelvis with lymph node metastases treated with the selective FGFR inhibitor AZD4547.

RESULTS

To date, the patient has been on a study drug for 32 months with acceptable tolerance and maintained radiological partial response as per RECIST 1.1 criteria. Exploratory biomarker analysis showed FGFR3, FGFR1, FGF-ligand and fibroblast growth factor receptor substrate 2 (FRS2) expression in the patient's tumour, together with the presence of a germ-line mutation in the FGFR3 extracellular binding domain. This is not a known hotspot mutation, and the functional significance remains unclear.

CONCLUSIONS

The FGFR inhibitor AZD4547 exhibits antitumour activity in a metastatic urothelial cancer displaying FGFR1, FGFR3, FGF-ligand and FRS2 expression. This lends support to the further exploration of FGFR inhibitors in urothelial cancer. Further studies are required to determinate the most effective way to select those patients most likely to respond.

Fibroblast Growth Factor (FGF) Receptor/FGF Inhibitors: Novel Targets and Strategies for Optimization of Response of Solid Tumors

The fibroblast growth factor receptor (FGFR) pathway plays a major role in several biological processes, from organogenesis to metabolism homeostasis and angiogenesis. Several aberrations, including gene amplifications, point mutations, and chromosomal translocations have been described across solid tumors. Most of these molecular alterations promote multiple steps of carcinogenesis in FGFR oncogene-addicted cells, increasing cell proliferation, angiogenesis, and drug resistance. Data suggest that upregulation of FGFR signaling is a common event in many cancer types. The FGFR pathway thus arises as a potential promising target for cancer treatment. Several FGFR inhibitors are currently under development. Initial preclinical results have translated into limited successful clinical responses when first-generation, nonspecific FGFR inhibitors were evaluated in patients. The future development of selective and unselective FGFR inhibitors will rely on a better understanding of the tissue-specific role of FGFR signaling and identification of biomarkers to select those patients who will benefit the most from these drugs. Further studies are warranted to establish the predictive significance of the different FGFR-aberrations and to incorporate them into clinical algorithms, now that second-generation, selective FGFR inhibitors exist.

Detection, Characterization, and Inhibition of FGFR-TACC Fusions in IDH Wild-type Glioma

PURPOSE

Oncogenic fusions consisting of fibroblast growth factor receptor (FGFR) and TACC are present in a subgroup of glioblastoma (GBM) and other human cancers and have been proposed as new therapeutic targets. We analyzed frequency and molecular features of FGFR-TACC fusions and explored the therapeutic efficacy of inhibiting FGFR kinase in GBM and grade II and III glioma.

EXPERIMENTAL DESIGN

Overall, 795 gliomas (584 GBM, 85 grades II and III with wild-type and 126 with IDH1/2 mutation) were screened for FGFR-TACC breakpoints and associated molecular profile. We also analyzed expression of the FGFR3 and TACC3 components of the fusions. The effects of the specific FGFR inhibitor JNJ-42756493 for FGFR3-TACC3-positive glioma were determined in preclinical experiments. Two patients with advanced FGFR3-TACC3-positive GBM received JNJ-42756493 and were assessed for therapeutic response.

RESULTS

Three of 85 IDH1/2 wild-type (3.5%) but none of 126 IDH1/2-mutant grade II and III gliomas harbored FGFR3-TACC3 fusions. FGFR-TACC rearrangements were present in 17 of 584 GBM (2.9%). FGFR3-TACC3 fusions were associated with strong and homogeneous FGFR3 immunostaining. They are mutually exclusive with IDH1/2 mutations and EGFR amplification, whereas they co-occur with CDK4 amplification. JNJ-42756493 inhibited growth of glioma cells harboring FGFR3-TACC3 in vitro and in vivo. The two patients with FGFR3-TACC3 rearrangements who received JNJ-42756493 manifested clinical improvement with stable disease and minor response, respectively.

CONCLUSIONS

RT-PCR sequencing is a sensitive and specific method to identify FGFR-TACC-positive patients. FGFR3-TACC3 fusions are associated with uniform intratumor expression of the fusion protein. The clinical response observed in the FGFR3-TACC3-positive patients treated with an FGFR inhibitor supports clinical studies of FGFR inhibition in FGFR-TACC-positive patients.

Role of the fibroblast growth factor receptor axis in cholangiocarcinoma

Advanced cholangiocarcinoma (CCA) is a highly lethal disease with limited therapeutic options beyond cytotoxic chemotherapy. Molecular profiling of CCA has provided insights into the pathogenesis of this disease and identified potential therapeutic targets. The fibroblast growth factor receptor (FGFR) axis is important for maintaining tissue homeostasis. Aberrations in FGFR activity have been implicated in the development and progression of CCA and other malignancies, which has generated significant interest in exploring FGFR's therapeutic potential. FGFR2 fusion events are present in up to 17% of intrahepatic CCAs and appear to predict sensitivity to FGFR inhibitors even after progression on chemotherapy. These observations have led to a clinical trial evaluating FGFR inhibition in patients with CCA enriched for FGFR alterations. This review summarizes current knowledge about the role of the FGFR pathway in cholangiocarcinogenesis and ongoing work in developing FGFR-directed therapies as an antineoplastic strategy for CCA.

FGFR3-TACC3: A novel gene fusion in cervical cancer

Cervical cancer epitomizes the success of cancer prevention through the human papillomavirus (HPV) vaccine, but significant challenges remain in the treatment of advanced disease. We report the first three cases of cervical carcinoma harboring an FGFR3-TACC3 fusion, which serves as a novel therapeutic target. The fusion, identified by comprehensive genomic profiling, activates the FGFR pathway that has been implicated in HPV-driven carcinogenesis. One of the patients whose tumor contained the FGFR3-TACC3 fusion was treated with an investigational FGFR tyrosine kinase inhibitor. Concomitant molecular alterations involving the PI3K/AKT/mTOR and RAF/MEK pathways were also identified and suggest other treatment strategies that deserve investigation. This case series highlights the role of comprehensive genomic profiling in the identification of new therapeutic targets and in targeted therapy selection for patients with cervical cancer.

[FGF/FGFR signalling: Implication in oncogenesis and perspectives]

Deregulation of FGF (fibroblast growth factor)/FGFR (fibroblast growth factor receptor) signalling leads to the promotion of several oncogenic mechanisms: proliferation, epithelial-mesenchymal transition, cytoskeleton modifications, migration and angiogenesis. Deregulation of this pathway is reported in various cancers at early stages, and can therefore be responsible for the emergence of the hallmarks of cancer. It is necessary to precise downstream pathways of FGFR signalling to understand its oncogenic potential. We will then describe its implications in different cancer types. Oncogenic mechanisms will be studied through the example of melanoma, in which deregulation of FGF/FGFR pathway is considered as a driver event and occurs in nearly 90% of cases. The FGF/FGFR signalling pathway is a putative therapeutic target. Numerous agents are in active development, operating through a selective or multi-targeted approach. Recent studies have shown rather disappointing results in non-selected patients, but promising results in patients with FGF/FGFR pathway alterations. A careful screening of patients is the key to a valuable evaluation of these new targeted molecular therapies.

Squamous cell lung cancer: from tumor genomics to cancer therapeutics

Squamous cell lung cancer (SCC) represents an area of unmet need in lung cancer research. For the past several years, therapeutic progress in SCC has lagged behind the now more common non-small cell lung cancer histologic subtype of adenocarcinoma. However, recent efforts to define the complex biology underlying SCC have begun to bear fruit in a multitude of ways, including characterization of previously unknown genomic and signaling pathways, delineation of new, potentially actionable molecular targets, and subsequent development of a large number of agents directed against unique SCC-associated molecular abnormalities. For the first time, SCC-specific prognostic gene signatures and predictive biomarkers of new therapeutic agents are emerging. In addition, recent and ongoing clinical trials, including the Lung-MAP master protocol, have been designed to facilitate approval of targeted therapy-biomarker combinations. In this comprehensive review, we describe the current status of SCC therapeutics, recent advances in the understanding of SCC biology and prognostic gene signatures, and the development of innovative new clinical trials, all of which offer new hope for patients with advanced SCC.

Precision and predictive medicine in urothelial cancer: are we making progress?

Therapy for urothelial carcinoma appears poised for a breakthrough on the basis of information regarding molecular subtypes and promising activity of PD-1/PD-L1 inhibitors. Precision medicine may be possible using rational marker-driven trial designs with enriched information from tumor genotyping and extreme responders.

Neoadjuvant chemotherapy in the management of muscle-invasive bladder cancer: bridging the gap between evidence and practice

Although cisplatin-based chemotherapy followed by radical cystectomy is the standard treatment of muscle-invasive bladder cancer, population-based studies reveal that only a small fraction of patients actually receive such treatment. A comprehensive understanding of the reasons for this gap between efficacy and effectiveness is necessary to increase the likelihood of cure of all patients with muscle-invasive bladder cancer. These reasons include systems-, provider-, and patient-level barriers that are not amenable to a single solution. Tackling each barrier will ultimately be necessary to bridge the disconnect between what is achievable and what is actually achieved.