Phase I and pharmacokinetic study of pazopanib and lapatinib combination therapy in patients with advanced solid tumors

Understanding and targeting resistance mechanisms in cancer

Resistance to cancer therapies has been a commonly observed phenomenon in clinical practice, which is one of the major causes of treatment failure and poor patient survival. The reduced responsiveness of cancer cells is a multifaceted phenomenon that can arise from genetic, epigenetic, and microenvironmental factors. Various mechanisms have been discovered and extensively studied, including drug inactivation, reduced intracellular drug accumulation by reduced uptake or increased efflux, drug target alteration, activation of compensatory pathways for cell survival, regulation of DNA repair and cell death, tumor plasticity, and the regulation from tumor microenvironments (TMEs). To overcome cancer resistance, a variety of strategies have been proposed, which are designed to enhance the effectiveness of cancer treatment or reduce drug resistance. These include identifying biomarkers that can predict drug response and resistance, identifying new targets, developing new targeted drugs, combination therapies targeting multiple signaling pathways, and modulating the TME. The present article focuses on the different mechanisms of drug resistance in cancer and the corresponding tackling approaches with recent updates. Perspectives on polytherapy targeting multiple resistance mechanisms, novel nanoparticle delivery systems, and advanced drug design tools for overcoming resistance are also reviewed.

Receptor Tyrosine Kinase Inhibitors for the Treatment of Recurrent and Unresectable Bone Sarcomas

Bone sarcomas are a heterogeneous group of rare tumors with a predominance in the young population. Few options of systemic treatment are available once they become unresectable and resistant to conventional chemotherapy. A better knowledge of the key role that tyrosine kinase receptors (VEGFR, RET, MET, AXL, PDGFR, KIT, FGFR, IGF-1R) may play in the pathogenesis of these tumors has led to the development of multi-target inhibitors (TKIs) that are progressively being incorporated into our therapeutic arsenal. Osteosarcoma (OS) is the most frequent primary bone tumor and several TKIs have demonstrated clinical benefit in phase II clinical trials (cabozantinib, regorafenib, apatinib, sorafenib, and lenvatinib). Although the development of TKIs for other primary bone tumors is less advanced, preclinical data and early trials have begun to show their potential benefit in advanced Ewing sarcoma (ES) and rarer bone tumors (chondrosarcoma, chordoma, giant cell tumor of bone, and undifferentiated pleomorphic sarcoma). Previous reviews have mainly provided information on TKIs for OS and ES. We aim to summarize the existing knowledge regarding the use of TKIs in all bone sarcomas including the most recent studies as well as the potential synergistic effects of their combination with other systemic therapies.

Small Molecule Inhibitors in Adult High-Grade Glioma: From the Past to the Future

Glioblastoma is the most common primary malignant tumor in the brain and has a dismal prognosis despite patients accepting standard therapies. Alternation of genes and deregulation of proteins, such as receptor tyrosine kinase, PI3K/Akt, PKC, Ras/Raf/MEK, histone deacetylases, poly (ADP-ribose) polymerase (PARP), CDK4/6, branched-chain amino acid transaminase 1 (BCAT1), and Isocitrate dehydrogenase (IDH), play pivotal roles in the pathogenesis and progression of glioma. Simultaneously, the abnormalities change the cellular biological behavior and microenvironment of tumor cells. The differences between tumor cells and normal tissue become the vulnerability of tumor, which can be taken advantage of using targeted therapies. Small molecule inhibitors, as an important part of modern treatment for cancers, have shown significant efficacy in hematologic cancers and some solid tumors. To date, in glioblastoma, there have been more than 200 clinical trials completed or ongoing in which trial designers used small molecules as monotherapy or combination regimens to correct the abnormalities. In this review, we summarize the dysfunctional molecular mechanisms and highlight the outcomes of relevant clinical trials associated with small-molecule targeted therapies. Based on the outcomes, the main findings were that small-molecule inhibitors did not bring more benefit to newly diagnosed glioblastoma, but the clinical studies involving progressive glioblastoma usually claimed “noninferiority” compared with historical results. However, as to the clinical inferiority trial, similar dosing regimens should be avoided in future clinical trials.

Review of the Mechanism of Nanocarriers and Technological Developments in the Field of Nanoparticles for Applications in Cancer Theragnostics

Cancer cannot be controlled by the usage of drugs alone, and thus, nanotechnology is an important technique that can provide the drug with an impetus to act more effectively. There is adequate availability of anticancer drugs that are classified as alkylating agents, hormones, or antimetabolites. Nanoparticle (NP) carriers increase the residence time of the drug, thereby enhancing the survival rate of the drug, which otherwise gets washed off owing to the small size of the drug particles by the excretory system. For example, for enhancing the circulation, a coating of nonfouling polymers like PEG and dextran is done. Famous drugs such as doxorubicin (DOX) are commonly encapsulated inside the nanocomposite. The various classes of nanoparticles are used to enhance drug delivery by aiding it to fight against the tumor. Targeted therapy aims to attack the cells with features common to the cancer cells while minimizing damage to the normal cell, and these therapies work in one in four ways. Some block the cancer cells from reproducing newer cells, others release toxic substances to kill the cancer cells, some stimulate the immune system to destroy the cancer cells, and some block the growth of more blood vessels around cancer cells, which starve the cells of the nutrients, which is needed for their growth. This review aims to testify the advancements nanotechnology has brought in cancer therapy, and its statements are supported with recent research findings and clinical trial results.

Diffuse Glioma Heterogeneity and Its Therapeutic Implications

Diffuse gliomas represent a heterogeneous group of universally lethal brain tumors characterized by minimally effective genotype-targeted therapies. Recent advances have revealed that a remarkable level of genetic, epigenetic, and environmental heterogeneity exists within each individual glioma. Together, these interconnected layers of intratumoral heterogeneity result in extreme phenotypic heterogeneity at the cellular level, providing for multiple mechanisms of therapeutic resistance and forming a highly adaptable and resilient disease. In this review, we discuss how glioma intratumoral heterogeneity and malignant cellular state plasticity drive resistance to existing therapies and look to a future in which these challenges may be overcome. SIGNIFICANCE: Glioma intratumoral heterogeneity and malignant cell state plasticity represent formidable hurdles to the development of novel targeted therapies. However, the convergence of genotypically diverse glioma cells into a limited set of epigenetically encoded transcriptional cell states may present an opportunity for a novel therapeutic strategy we call "State Selective Lethality." In this approach, cellular states (as opposed to genetic perturbations/mutations) are the subject of therapeutic targeting, and plasticity-mediated resistance is minimized through the design of cell state "trapping agents."

Association between clinically relevant toxicities of pazopanib and sunitinib and the use of weak CYP3A4 and P-gp inhibitors

PURPOSE

Sunitinib and pazopanib, two tyrosine kinase inhibitors (TKI), may be targets of potential pharmacokinetic drug-drug interactions (P-PK-DDIs). While strong cytochrome P4503A (CYP3A4) inhibitors or inducers should cause a clinically relevant modification in plasma TKI concentrations, the effect of weak inhibitors is unknown. The objective of this study was to evaluate the association between weak P-PK-DDI and clinically relevant toxicity in real life.

PATIENTS AND METHODS

This was a single-center retrospective study including patients treated with sunitinib or pazopanib for any malignancies, for whom a PK-DDI analysis was performed before starting TKI. The primary endpoint was the correlation between P-PK-DDIs and a dose decrease after 1 month of treatment. The secondary endpoint was the correlation between PK-DDIs and drug withdrawal due to toxicity.

RESULTS

Seventy-six patients were assessed. A P-PK-DDI with weak CYP3A4 or P-gp inhibition was found in 14 patients. In patients with P-PK-DDI or without, the dose was reduced during the first month in 57.1% and 17.7% (p = 0.003) and the drug withdrawn in 42.8% and 11.3% (p = 0.011), respectively. In multivariate analysis, a significant correlation was found between P-PK-DDI (CYP3A4 and P-gp inhibitors) and dose reduction, and between drug withdrawal and PK-DDI (CYP3A4 inhibitors).

CONCLUSION

P-PK-DDI was correlated with dose reduction and drug withdrawal due to toxicity. The causality of this relationship warrants to be assessed; therefore, therapeutic drug monitoring is necessary in patients treated with TKI.

Reversible Hypopigmentation with Pazopanib

Tablet Pazopanib known to cause Hypo pigmentation and Hyperpigmentation as per various literature reports. We report here a case of reversible hypopigmentation with Pazopanib in a patient treated for spindle cell sarcoma. Patient did not have any clinical symptoms except for cosmetic significance.

Combined kinase inhibitors of MEK1/2 and either PI3K or PDGFR are efficacious in intracranial triple-negative breast cancer

Background

Triple-negative breast cancer (TNBC), lacking expression of hormone and human epidermal growth factor receptor 2 receptors, is an aggressive subtype that frequently metastasizes to the brain and has no FDA-approved systemic therapies. Previous literature demonstrates mitogen-activated protein kinase kinase (MEK) pathway activation in TNBC brain metastases. Thus, we aimed to discover rational combinatorial therapies with MEK inhibition, hypothesizing that co-inhibition using clinically available brain-penetrant inhibitors would improve survival in preclinical models of TNBC brain metastases.

Methods

Using human-derived TNBC cell lines, synthetic lethal small interfering RNA kinase screens were evaluated with brain-penetrant inhibitors against MEK1/2 (selumetinib, AZD6244) or phosphatidylinositol-3 kinase (PI3K; buparlisib, BKM120). Mice bearing intracranial TNBC tumors (SUM149, MDA-MB-231Br, MDA-MB-468, or MDA-MB-436) were treated with MEK, PI3K, or platelet derived growth factor receptor (PDGFR; pazopanib) inhibitors alone or in combination. Tumors were analyzed by western blot and multiplexed kinase inhibitor beads/mass spectrometry to assess treatment effects.

Results

Screens identified MEK+PI3K and MEK+PDGFR inhibitors as tractable, rational combinations. Dual treatment of selumetinib with buparlisib or pazopanib was synergistic in TNBC cells in vitro. Both combinations improved survival in intracranial SUM149 and MDA-MB-231Br, but not MDA-MB-468 or MDA-MB-436. Treatments decreased mitogen-activated protein kinase (MAPK) and PI3K (Akt) signaling in sensitive (SUM149 and 231Br) but not resistant models (MDA-MB-468). Exploratory analysis of kinome reprogramming in SUM149 intracranial tumors after MEK ± PI3K inhibition demonstrates extensive kinome changes with treatment, especially in MAPK pathway members.

Conclusions

Results demonstrate that rational combinations of the clinically available inhibitors selumetinib with buparlisib or pazopanib may prove to be promising therapeutic strategies for the treatment of some TNBC brain metastases. Additionally, effective combination treatments cause widespread alterations in kinase pathways, including targetable potential resistance drivers.

The role of pazopanib on tumour angiogenesis and in the management of cancers: A review

Pazopanib is a relatively new compound to be introduced into the chemotherapy field. It is thought to have decent anti-angiogenic properties, which gives an additional hope for the treatment of certain types of cancers. A systematic review solely discussing about pazopanib and its anti-angiogenic effect is yet to be published to date, despite several relevant clinical trials being conducted over the recent years. In this review, we aim to investigate the mechanism of pazopanib's anti-angiogenic effect and its effectiveness in treating several cancers. We have included, in this study, findings from electronically searchable data from randomized clinical trials, clinical studies, cohort studies and other relevant articles. A total of 352 studies were included in this review. From the studies, the effect of pazopanib in various cancers or models was observed and recorded. Study quality is indefinite, with a few decent quality articles. The most elaborately studied cancers include renal cell carcinoma, solid tumors, advanced solid tumors, soft tissue sarcoma, breast cancer and gynecological cancers. In addition, several less commonly studied cancers are included in the studies as well. Pazopanib had demonstrated its anti-angiogenic effect based on favorable results observed in cancers, which are caused by angiogenesis-related mechanisms, such as renal cell carcinoma, solid tumors, advanced solid tumors and soft tissue sarcoma. This review was conducted to study, analyze and review the anti-angiogenic properties of pazopanib in various cancers. The results obtained can provide a decent reference when considering treatment options for angiogenesis-related malignancies. Furthermore, the definite observations of the anti-angiogenic effects of pazopanib could provide newer insights leading to the future development of drugs of the same mechanism with increased efficiency and reduced adverse effects.

Cyberknife stereotactic radiosurgery and denosumab for giant cell tumour of the skull base: Case report

Giant cell tumours (GCT) of the skull is a rare entity with only small number of cases reported in literature and optimal treatment is yet to be determined. These tumours have shown high recurrence rates after incomplete surgery, usually occurring during the first year. Even with new surgical techniques a complete resection in skull base tumours is not always possible without functional compromise. Therefore, adjuvant therapy is essential to enhance local control and quality of life. We report a rare case of a 34-year-old male with giant cell tumour (GCT) of the skull base involving the petrous bone, clivus and sphenoid body. The patient received Cyberknife stereotactic radiosurgery (CK SRS) and denosumab after surgery. This combined therapy allowed local control and tumour reduction with secondary neurological improvement during a 4-year follow up.

Combine and conquer: challenges for targeted therapy combinations in early phase trials

Our increasing understanding of cancer biology has led to the development of molecularly targeted anticancer drugs. The full potential of these agents has not, however, been realised, owing to the presence of de novo (intrinsic) resistance, often resulting from compensatory signalling pathways, or the development of acquired resistance in cancer cells via clonal evolution under the selective pressures of treatment. Combinations of targeted treatments can circumvent some mechanisms of resistance to yield a clinical benefit. We explore the challenges in identifying the best drug combinations and the best combination strategies, as well as the complexities of delivering these treatments to patients. Recognizing treatment-induced toxicity and the inability to use continuous pharmacodynamically effective doses of many targeted treatments necessitates creative intermittent scheduling. Serial tumour profiling and the use of parallel co-clinical trials can contribute to understanding mechanisms of resistance, and will guide the development of adaptive clinical trial designs that can accommodate hypothesis testing, in order to realize the full potential of combination therapies.

Clinical pharmacology, drug-drug interactions and safety of pazopanib: a review

INTRODUCTION

In the past decade, treatment options for metastatic renal cell carcinoma and soft-tissue sarcoma have expanded. Pazopanib was discovered during the screening of compounds that suppressed vascular endothelial growth factor receptor-2 (VEGFR-2). As other tyrosine kinase inhibitors (TKI), pazopanib is not totally specific for one target since it also inhibits stem-cell factor receptor (cKIT), platelet-derived growth factor receptors (PDGFRα, β), VEGFR-1 and -3. Areas covered: Clinical pharmacology, drug-drug interactions and safety data published on pazopanib, between January 2006 and April 2016, are reviewed. Expert opinion: This new therapy has been shown to improve progression-free survival compared with previous approaches, in renal cell cancer and soft-tissue sarcoma. However, some specific sub-populations, such as elderly patients, patients with brain metastases or with Eastern Cooperative Oncology Group Performance Status (ECOG PS) 2 or comorbidities, are poorly represented in pivotal pazopanib phase III studies. Pazopanib meets criteria defining therapies as candidates for therapeutic drug monitoring: large intra- and inter-patient pharmacokinetic variability, potential pharmacokinetic drug-drug interactions, pharmacokinetic/pharmacodynamic relationship and narrow therapeutic index. Knowledge of predictors that can be used to guide dosing regimens in the target population and in special populations needs to be improved.

Systemic therapy for selected skull base sarcomas: Chondrosarcoma, chordoma, giant cell tumour and solitary fibrous tumour/hemangiopericytoma

This review highlights the data currently available on the activity of systemic therapy in chondrosarcoma, chordoma, giant cell tumour of the bone (GCTB) and solitary fibrous tumour, i.e., four rare sarcomas amongst mesenchymal malignancy arising from the skull base.

Preclinical Modeling of Tumor Growth and Angiogenesis Inhibition to Describe Pazopanib Clinical Effects in Renal Cell Carcinoma

The objective was to leverage tumor size data from preclinical experiments to propose a model of tumor growth and angiogenesis inhibition for the analysis of pazopanib efficacy in renal cell carcinoma (RCC) patients. We analyzed tumor data in mice with RCC CAKI‐2 cell line treated with pazopanib. Clinical tumor size data obtained in a subset of patients with RCC were also analyzed. A model accounting for the processes of tumor growth, angiogenesis, and drug effect was developed. The final tumor model was composed of two variables: the tumor and its vasculature. Our results show that, both in mice and in humans, pazopanib exhibits a dual mechanism of action, and parameter estimation values highlight the inherent difference between mice and humans on the time scale of tumor size response. We developed a semimechanistic tumor growth inhibition model that takes into account tumor angiogenesis in order to describe the effects of pazopanib in mice. Analyzing rich preclinical data with a semimechanistic model may be a relevant approach to facilitate the description of sparse clinical longitudinal tumor size data and to provide insights for the understanding of the drug mechanisms of action in patients.

Metabolism-related pharmacokinetic drug-drug interactions with tyrosine kinase inhibitors: current understanding, challenges and recommendations

Drug-drug interactions (DDIs) occur when a patient's response to the drug is modified by administration or co-exposure to another drug. The main cytochrome P450 (CYP) enzyme, CYP3A4, is implicated in the metabolism of almost all of the tyrosine kinase inhibitors (TKIs). Therefore, there is a substantial potential for interaction between TKIs and other drugs that modulate the activity of this metabolic pathway. Cancer patients are susceptible to DDIs as they receive many medications, either for supportive care or for treatment of toxicity. Differences in DDI outcomes are generally negligible because of the wide therapeutic window of common drugs. However for anticancer agents, serious clinical consequences may occur from small changes in drug metabolism and pharmacokinetics. Therefore, the objective of this review is to highlight the current understanding of DDIs among TKIs, with a focus on metabolism, as well as to identify challenges in the prediction of DDIs and provide recommendations.

A phase 1 study of intermittently administered pazopanib in combination with continuous daily dosing of lapatinib in patients with solid tumors

PURPOSE

Preclinically, pazopanib/lapatinib combination acted synergistically to suppress the activity of multiple tyrosine kinases, including VEGFR-1, 2, 3, PDGFR and c-kit (pazopanib), HER1/EGFR and HER2 (lapatinib), and several other tyrosine kinases including c-Met through, plausibly, network inhibition effects. Clinically, continuous dosing of pazopanib/lapatinib combination was associated with a higher response rate than with lapatinib monotherapy, with poor tolerance. We explored multiple intermittent dose levels of pazopanib combined with continuous daily dosing of lapatinib in patients with solid tumors.

METHODS

The present study used a phase 1, modified 3 + 3, dose-escalation design to evaluate the safety and tolerability of the combination of orally received pazopanib once every other day with continuous daily dosing of lapatinib for 28 days. In the expansion phase, tumor response was evaluated in patients with specific genetic alterations (HER2 amplification, HER2 mutation, c-Met amplification, c-Met mutation, and EGFR mutation).

RESULTS

Twenty-four patients were treated. The most common drug-related adverse events were fatigue 7/24 (29%), skin rash 5/21 (21%), and diarrhea 3/24 (17%), with 4/24 (16%) patients experiencing grade ≥3 drug-related adverse events. Escalation to the FDA-approved dose (800 mg daily for pazopanib and 1500 mg every day for lapatinib) was not feasible due to toxicities. Pazopanib 200 mg every other day + lapatinib 500 mg daily was considered the maximum tolerated dose (MTD). No tumor response was observed, including in patients with the specific molecular genetic alterations tested.

CONCLUSION

Every other day dosing of pazopanib combined with daily lapatinib was tolerated at the established MTD, but no complete or partial tumor responses were observed at these dose levels.

Mechanism-based inactivation of CYP450 enzymes: a case study of lapatinib

Mechanism-based inactivation (MBI) of CYP450 enzymes is a unique form of inhibition in which the enzymatic machinery of the victim is responsible for generation of the reactive metabolite. This precondition sets up a time-dependency for the inactivation process, a hallmark feature that characterizes all MBI. Yet, MBI itself is a complex biochemical phenomenon that operates in different modes, namely, covalent binding to apoprotein, covalent binding of the porphyrin group and also complexation of the catalytic iron. Using lapatinib as a recent example of toxicological interest, we present an example of a mixed-function MBI that can confound clinical drug-drug interactions manifestation. Lapatinib exhibits both covalent binding to the apoprotein and formation of a metabolite-intermediate complex in an enzyme-selective manner (CYP3A4 versus CYP3A5), each with different reactive metabolites. The clinical implication of this effect is also contingent upon genetic polymorphisms of the enzyme involved as well as the co-administration of other substrates, inhibitors or inducers, culminating in drug-drug interactions. This understanding recapitulates the importance of applying isoform-specific mechanistic investigations to develop customized strategies to manage such outcomes.

Pazopanib for the treatment of renal cell carcinoma

The incidence and mortality from renal cell cancer (RCC) is increasing. RCC tumors are particularly vascular in nature as a result of disruption of the VHL gene and/or its upstream pathway leading to upregulation of the hypoxia-inducible factor transcription factor. The hypoxia-inducible factor pathway drives angiogenesis by upregulating VEGF and bFGF, amongst other proangiogenic downstream target genes. Therapies which target angiogenesis have been successful in treating metastatic RCC (mRCC) and the receptor tyrosine kinase inhibitor, pazopanib, is licensed for first line treatment of mRCC. This review details the past, current and future roles of pazopanib in the treatment of mRCC.

Pharmacokinetic interaction of entinostat and lapatinib following single and co-oral administration in rats

1. Entinostat, also known as SNDX-275 or MS-275, is a novel, potent, orally bioavailable, class I selective histone deacetylase inhibitor. Pre-clinical data has show that MS-275 can enhance the activity of lapatinib in HER(2+) metastatic inflammatory and non-inflammatory breast cancer. This study examined whether oral administration of MS-275 to the rats with lapatinib led to any pharmacokinetic interactions. 2. To evaluate pharmacokinetic interaction of MS-275 and lapatinib in rat, a sensitive and simple LC-MS method was developed to simultaneously determine MS-275 and lapatinib in rat plasma with carbamazepine as internal standard (IS). Eighteen rats were divided randomly into three groups, lapatinib group (lapatinib 15 mg/kg, n = 8), MS-275 group (MS-275 15 mg/kg, n = 8) and co-administration group (MS-275 15 mg/kg and lapatinib 15 mg/kg, n = 8). 3. There was no statistical pharmacokinetics difference for MS-275 in MS-275 group and co-administration group; the lapatinib could not influence the pharmacokinetic profile of MS-275 in rats. However, there is a statistical pharmacokinetics difference between lapatinib in the lapatinib group and co-administration group, when co-oral administration MS-275 with lapatinib, AUC increased from 2375.5 to 9900.3 ng/mL h (p < 0.05), Cmax increased from 538.0 to 2578.2 ng/mL (p < 0.01), CL decreased from 6.2 to 1.7 L/h/kg (p < 0.01). 4. These data indicate MS-275 could obviously influence the pharmacokinetic profile of lapatinib in rats, which might cause drug-drug interactions in humans when using lapatinib with MS-275. Further investigations should be carried out to elucidate the synergistic mechanisms between the two drugs.

Phase I study of weekly paclitaxel in combination with pazopanib and lapatinib in advanced solid malignancies

Background:

We assessed the maximum tolerated regimen (MTR) and dose-limiting toxicities of pazopanib and lapatinib in combination with weekly paclitaxel, and the effect of pazopanib and lapatinib on paclitaxel pharmacokinetics.

Methods:

Patients received intravenous paclitaxel on days 1, 8, and 15 of a 28-day cycle concurrently with daily pazopanib and lapatinib. Dose levels of paclitaxel (mg m⁻²)/pazopanib(mg)/lapatinib(mg) were 50/400/1000, 50/800/1000, 80/800/1000, and 80/400/1000. At the MTR, additional patients were enrolled to further evaluate tolerability, and the potential effects of pazopanib and lapatinib, inhibitors of cytochrome P450 (CYP)3A4, on the pharmacokinetics of paclitaxel, a CYP2C8 and CYP3A4 substrate.

Results:

Twenty-six patients were enrolled. Dose-limiting toxicities at the MTR (80/400/1000) included grade 4 thrombosis and grade 3 aspartate aminotransferase elevation. Other toxicities included diarrhoea, neutropenia, fatigue, and liver enzyme elevations. Coadministration of pazopanib 400 mg and lapatinib 1000 mg increased paclitaxel maximum plasma concentration (38%) and area under the curve (37%) relative to paclitaxel alone. One patient with a salivary gland tumour had a partial response; three patients had stable disease (⩾6 months).

Conclusions:

Pazopanib 400 mg per day and lapatinib 1000 mg per day can be combined with paclitaxel 80 mg m⁻² in 28-day cycles. Coadministration of pazopanib and lapatinib, weak inhibitors of CYP2C8 and CYP3A4, had an inhibitory effect on paclitaxel clearance.

Profile of pazopanib and its potential in the treatment of epithelial ovarian cancer

Epithelial ovarian cancer (EOC) is the most lethal gynecological cancer. Recently, clinical trials have focused on novel antiangiogenic agents in combination with chemotherapy or alone in women with primary and recurrent ovarian cancer. Antiangiogenic agents include monoclonal antibodies, tyrosine-kinase inhibitors, and peptibodies. Many of these agents, including bevacizumab, pazopanib, nintedanib, cediranib, and trebananib, have been evaluated in randomized Phase III clinical trials, and all have demonstrated a progression-free survival (PFS) benefit. Specifically, maintenance pazopanib was shown to improve PFS in women with newly diagnosed EOC. Pazopanib, an oral TKI, inhibits several kinase receptors, including those for vascular endothelial growth factor (-1,-2,-3), platelet-derived growth factor (-α and -β), and fibroblast growth factor. It also targets stem cell-factor receptor (c-kit), interleukin 2-inducible T-cell kinase, lymphocyte-specific protein tyrosine kinase, and colony-stimulating factor 1 receptor. Pazopanib has been investigated in several Phase II and III clinical trials, with results indicating a potential role in the management of EOC. This article provides an overview of pazopanib in the treatment of EOC.

Investigational platelet-derived growth factor receptor kinase inhibitors in breast cancer therapy

INTRODUCTION

Aberrant regulation of platelet-derived growth factors (PDGFs) and their receptors (PDGFR) has been shown to be involved in many solid tumors, including breast cancer. PDGFR-α and PDGFR-β expressions were documented in breast cancer and are correlated with tumor aggressiveness and metastasis. Preclinical evidence further suggests tumor stimulatory roles of PDGFRs expressed by tumor stroma cells and indicates a deleterious effect of stromal PDGFRs on intratumoral drug uptake.

AREAS COVERED

This review summarizes the present understanding of PDGF signaling in breast cancer based on experimental studies and available clinical trials. It also provides a critical discussion of selected ongoing clinical trials in patients with breast cancer involving PDGFR inhibition with tyrosine kinase inhibitors, specifically in endocrine responsive breast cancer.

EXPERT OPINION

An increased molecular understanding of response and resistance mechanisms to endocrine therapy will be essential for therapeutic advances in PDGFR-directed cancer therapy. Future developments in the field will rely on clinical studies where prospective analyses of target expression in breast cancer cells and in the tumor stroma are included. More selective PDGFR inhibitors with reduced side effects will be crucial for combinatorial therapies. Development of sensitive diagnostics is of critical importance for patient selection and monitoring of therapeutic effects.

Retrospective analysis of patients with rare-site and metastatic giant cell tumor

A giant cell tumor occurs mainly in the proximal tibia, humerus, distal radius bone and the pelvic bone. It is rarely observed in such sites as the ribs and the temporal bone. The condition is primarily treated with surgical excision and functional reconstruction. The effect of chemotherapy on lung metastases and locally advanced giant cell tumors has remained unknown. We collected and analyzed the data of six patients with rare giant cell tumors located in the head and neck patients. After an average follow-up of 42.6 months after surgery (14 to 90 months), no local recurrence or metastasis was observed. We also collected and analyzed the data of five patients with metastatic giant cell tumors who were undergoing surgery for the primary tumor before; of three patients who had experienced multiple chemotherapy cycles, one had spontaneous regression, and one survived for long timer despite progression. The other two patients had their major metastatic lesions resected by surgery, and presented long-term survival during the follow up. In addition, this study reports one patient with locally advanced giant cell tumor of the rib, who has undergone successful surgical resection following two cycles of chemotherapy with ifosfamide and liposomal doxorubicin. Complete resection of the lesion at the head and neck is the key to relapse-free survival. The prognosis of lung metastases in patients with giant cell tumors is relatively satisfying. Neoadjuvant chemotherapy is also conducive to the surgery for locally advanced lesions and improvement of the quality of life.