Gastric cancer (GC) represents a major cancer burden worldwide, and remains the second leading cause of cancer-related death. Due to its insidious nature, presentation is usually late and often carries a poor prognosis. Despite having improved treatment modalities over the last decade, for most patients only modest improvements have been seen in overall survival. Recent progress in understanding the molecular biology of GC and its signaling pathways, offers the hope of clinically significant promising advances for selected groups of patients. Patients with Her-2 overexpression or amplification have experienced benefit from the integration of monoclonal antibodies such as trastuzumab to the standard chemotherapy. Additionally, drugs targeting angiogenesis (bevacizumab, sorafenib, sunitinib) are under investigation and other targeted agents such as mTOR inhibitors, anti c-MET, polo-like kinase 1 inhibitors are in preclinical or early clinical development. Patient selection and the development of reliable biomarkers to accurately select patients most likely to benefit from these tailored therapies is now key. Future trials should focus on these advances to optimize the treatment for GC patients. This article will review recent progress and current status of targeted agents in GC.
gastric cancer; molecular targeted agents; monoclonal antibody; tyrosine kinase inhibitor
An understanding of vascular endothelial growth factor (VEGF) and mammalian target of rapamycin (mTOR) pathways has greatly changed the way metastatic renal cell carcinoma (RCC) is treated. Based on available phase III randomized trials, anti-VEGF agents such as sunitinib, sorafenib, bevacizumab-based therapy, and mTOR-targeted agents such as temsirolimus and everolimus have been used in the treatment armamentarium for this disease. Now that agents directed against these pathways have largely replaced immunotherapy as the standard of care, new questions have emerged and are the subject of ongoing clinical trials. The development of new targeted therapies including axitinib, pazopanib, cediranib, volociximab, tivozanib (AV-951), BAY 73-4506, and c-met inhibitors such as GSK1363089 and ARQ197 may potentially expand the list of treatment options. Sequential and combination targeted therapies are currently under investigation in advanced disease as are adjuvant and neo-adjuvant approaches around nephrectomy.
adjuvant; combination therapy; mammalian target of rapamycin; neo-adjuvant; nonclear cell histologies; renal cell carcinoma; vascular endothelial growth factor
Several therapies targeting angiogenesis are currently in development for non-small cell lung cancer (NSCLC). This review discusses results of recent clinical trials evaluating chemotherapy plus antiangiogenic therapy for NSCLC. Bevacizumab, an anti-VEGF antibody, is currently approved for the treatment of advanced NSCLC in combination with carboplatin and paclitaxel. Completed phase III trials evaluating bevacizumab plus chemotherapy have shown prolonged progression-free survival; however, not all trials showed significant improvement in overall survival (OS). Phase III trials of the tyrosine kinase inhibitors (TKIs) vandetanib and sorafenib and the vascular disrupting agent ASA404 also failed to improve OS compared with chemotherapy alone. Clinical trials are ongoing involving several new antiangiogenic therapies, including ramucirumab, aflibercept, cediranib, nintedanib (BIBF 1120), sunitinib, pazopanib, brivanib, ABT-869, axitinib, ABT-751 and NPI-2358; several of these agents have shown promising phase I/II results. Results from recently completed and ongoing phase III trials will determine if these newer antiangiogenic agents will be incorporated into clinical practice.
non-small cell lung cancer; antiangiogenic therapy; vascular endothelial growth factor; angiogenesis; tyrosine kinase inhibitor; monoclonal antibody; chemotherapy
Brain metastases (BM) are the most common intracranial tumors and their incidence is increasing. Untreated brain metastases are associated with a poor prognosis and a poor performance status. Metastasis development involves the migration of a cancer cell from the bulk tumor into the surrounding tissue, extravasation from the blood into tissue elsewhere in the body, and formation of a secondary tumor. In the recent past, important results have been obtained in the management of patients affected by BM, using surgery, radiation therapy, or both. Conventional chemotherapies have generally produced disappointing results, possibly due to their limited ability to penetrate the blood–brain barrier. The advent of new technologies has led to the discovery of novel molecules and pathways that have better depicted the metastatic process. Targeted therapies such as bevacizumab, erlotinib, gefitinib, sunitinib and sorafenib, are all licensed and have demonstrated improved survival in patients with metastatic disease. In this review, we will report current data on targeted therapies. A brief review about brain metastatic process will be also presented.
angiogenesis; blood-brain barrier; brain metastases; cancer stem cells; microRNA; targeted therapy
Background and purpose
Targeted drugs have augmented the cancer treatment armamentarium. Based on the molecular specificity, it was initially believed that these drugs had significantly less side effects. However, currently it is accepted that all of these agents have their specific side effects. Based on the given multimodal approach, special emphasis has to be placed on putative interactions of conventional cytostatic drugs, targeted agents and other modalities. The interaction of targeted drugs with radiation harbours special risks, since the awareness for interactions and even synergistic toxicities is lacking. At present, only limited is data available regarding combinations of targeted drugs and radiotherapy. This review gives an overview on the current knowledge on such combined treatments.
Materials and methods
Using the following MESH headings and combinations of these terms pubmed database was searched: Radiotherapy AND cetuximab/trastuzumab/panitumumab/nimotuzumab, bevacizumab, sunitinib/sorafenib/lapatinib/gefitinib/erlotinib/sirolimus, thalidomide/lenalidomide as well as erythropoietin. For citation crosscheck the ISI web of science database was used employing the same search terms.
Several classes of targeted substances may be distinguished: Small molecules including kinase inhibitors and specific inhibitors, antibodies, and anti-angiogenic agents. Combination of these agents with radiotherapy may lead to specific toxicities or negatively influence the efficacy of RT. Though there is only little information on the interaction of molecular targeted radiation and radiotherapy in clinical settings, several critical incidents are reported.
The addition of molecular targeted drugs to conventional radiotherapy outside of approved regimens or clinical trials warrants a careful consideration especially when used in conjunction in hypo-fractionated regimens. Clinical trials are urgently needed in order to address the open question in regard to efficacy, early and late toxicity.
radiotherapy; molecular targeted drugs; antibodies; TKI; toxicity
Chemotherapy and immunotherapy failed to deliver decisive results in the systemic treatment of metastatic
renal cell carcinoma. Agents representing the current standards operate on members of the RAS signal transduction
pathway. Sunitinib (targeting vascular endothelial growth factor), temsirolimus (an inhibitor of the mammalian target of
rapamycin - mTOR) and pazopanib (a multi-targeted receptor tyrosine kinase inhibitor) are used in the first line of
recurrent disease. A combination of bevacizumab (inhibition of angiogenesis) plus interferon α is also first-line therapy.
Second line options include everolimus (another mTOR inhibitor) as well as tyrosine kinase inhibitors for patients who
previously received cytokine. We review the results of clinical investigations focusing on survival benefit for these agents.
Additionally, trials focusing on new agents, including the kinase inhibitors axitinib, tivozanib, dovitinib and cediranib and
monoclonal antibodies including velociximab are also discussed. In addition to published outcomes we also include
follow-up and interim results of ongoing clinical trials. In summary, we give a comprehensive overview of current
advances in the systemic treatment of metastatic renal cell carcinoma.
Biomarkers; everolimus; renal cell cancer; sunitinib; temsirolimus; tyrosine kinase inhibitors.
Epidermal growth factor receptor tyrosine kinase inhibitors gefitinib and erlotinib have been widely used in patients with non-small-cell lung cancer. Unfortunately, the efficacy of EGFR-TKIs is limited because of natural and acquired resistance. As a novel cytoprotective mechanism for tumor cell to survive under unfavorable conditions, autophagy has been proposed to play a role in drug resistance of tumor cells. Whether autophagy can be activated by gefitinib or erlotinib and thereby impair the sensitivity of targeted therapy to lung cancer cells remains unknown. Here, we first report that gefitinib or erlotinib can induce a high level of autophagy, which was accompanied by the inhibition of the PI3K/Akt/mTOR signaling pathway. Moreover, cytotoxicity induced by gefitinib or erlotinib was greatly enhanced after autophagy inhibition by the pharmacological inhibitor chloroquine (CQ) and siRNAs targeting ATG5 and ATG7, the most important components for the formation of autophagosome. Interestingly, EGFR-TKIs can still induce cell autophagy even after EGFR expression was reduced by EGFR specific siRNAs. In conclusion, we found that autophagy can be activated by EGFR-TKIs in lung cancer cells and inhibition of autophagy augmented the growth inhibitory effect of EGFR-TKIs. Autophagy inhibition thus represents a promising approach to improve the efficacy of EGFR-TKIs in the treatment of patients with advanced non-small-cell lung cancer.
The survival rates of patients with squamous cell carcinoma of the head and neck (HNSCC) have not improved significantly despite multi-modality therapy, including surgery, radiation therapy, and chemotherapy. Recently, molecular targeted agents have shown significant improvement in clinical outcomes; for example, in chronic myelogeneous leukemia with imatinib, breast cancer with trastuzumab, colon cancer with bevacizumab and cetuximab, and renal cell cancer with sorafenib and sunitinib. In HNSCC, the epidermal growth factor receptor antibody cetuximab has shown promising results in combination with radiation. Targeted agents including cetuximab induce stresses to activate prosurvival autophagy. Combining autophagy inhibitors with agents that induce autophagy as a prosurvival response may therefore increase their therapeutic efficacy. Whether autophagy contributes to the prosurvival response or to the antitumor effect of chemotherapeutic drugs is largely unknown. This review will discuss the possible role of autophagy as a novel target for anticancer therapy agents in HNSCC.
head and neck squamous cell carcinoma; molecular targeted agents; epidermal growth factor; autophagy; autophagic cell death; autophagic resistance; apoptosis
Treatment of metastatic renal cell carcinoma (mRCC) has evolved rapidly over the last two decades as major pathways involved in pathogenesis have been elucidated. These include the vascular endothelial growth factor (VEGF) axis and mammalian target of rapamycin (mTOR). Therapies targeting the VEGF pathway include bevacizumab, sorafenib, sunitinib, pazopanib, and axitinib, whereas temsirolimus and everolimus inhibit the mTOR pathway. All of these novel therapies—VEGF and mTOR inhibitors—are associated with a variety of unique toxicities, some of which may necessitate expert medical management, treatment interruption, or dose reduction. Common adverse events with newer drugs include hypertension, skin reactions, gastrointestinal disturbances, thyroid dysfunction, and fatigue. Skilled management of these toxicities is vital to ensure optimal therapeutic dosing and maximize patient outcomes, including improved survival and quality of life. This review describes and compares the toxicity profiles of novel molecularly targeted agents used in the treatment of mRCC and presents guidance on how best to prevent and manage treatment-related toxicities. Particular attention is given to axitinib, the newest agent to enter the armamentarium. Axitinib is a second-generation receptor tyrosine kinase inhibitor with potent VEGF receptor inhibition that provides durable responses and superior progression-free survival in advanced RCC compared with sorafenib.
Axitinib; Renal cell carcinoma; Tyrosine kinase inhibitor; Toxicity; Adverse events
With the increasing understanding of the biology of the disease and the development of targeted therapy, there has been a paradigm shift in the treatment of clear cell metastatic renal cell carcinoma (mRCC). Traditionally patients with metastatic RCC have been treated with immunotherapy which has limited efficacy. The multikinase inhibitors sunitinib, sorafenib and pazopanib, the VEGF antibody bevacizumab in combination with interferon and the mTOR inhibitor temsirolimus have all been shown to prolong progression-free survival in phase III studies. Here we review another mTOR inhibitor, everolimus (Afinitor®; Novartis, USA) which was approved in March 2009 by the US FDA for treatment of targeted-therapy refractory metastatic renal cell cancer. The phase III study of everolimus (the RECORD study) was terminated early after a significant difference in efficacy was noted in the treatment arm with everolimus (progression-free survival of 4.0 months in patients on the treatment arm vs 1.9 months in the placebo arm). The most common adverse events were stomatitis, pneumonitis, fatigue and infections. We review Phase I–III data with a particular emphasis on safety data and patient focused outcomes.
metastatic renal cell carcinoma; targeted therapy; mTOR; everolimus
With an explosion of available treatments for metastatic renal cell carcinoma (mRCC) in recent years, it is important to recognize that approved targeted therapies fall broadly into only two mechanistic categories. The first category, vascular endothelial growth factor (VEGF)-directed therapies, includes sunitinib, pazopanib, sorafenib and bevacizumab. The second category includes inhibitors of the mammalian target of rapamycin (mTOR), namely everolimus and temsirolimus. A pivotal trial of ever-olimus supports use of the agent in patients with mRCC refractory to VEGF- tyrosine kinase inhibitors (TKI) therapy, while pivotal data for temsirolimus supports use in poor-prognosis patients as first-line therapy. Multiple reviews exist to delineate the laboratory and clinical development of mTOR inhibitors. This paper will outline the future applications of these therapies. It will explore ongoing trials evaluating combinations of mTOR inhibitors with other targeted therapies, along with sequencing strategies and biomarker discovery efforts. The application of mTOR inhibitors in unique populations is also described.
mTOR; Everolimus; Temsirolimus; Deferolimus; INTORACT; TORAVA; BeST; Biomarkers; Clinical trials
Metastatic clear cell renal cell cancer has traditionally been treated with cytokines (interferon or interleukin-2). Improved understanding of biology has engendered novel targeted therapeutic agents that have altered the natural history of this disease. The vascular endothelial growth factor and its related receptor and the mTOR signal transduction pathway have particularly been exploited. Sunitinib malate, sorafenib tosylate, temsirolimus, and bevacizumab have improved clinical outcomes in randomized trials. Other multitargeted tyrosine kinase inhibitors (lapatinib, axitinib, pazopanib) and antiangiogenic agents (VEGF Trap, lenalidomide) have also demonstrated activity in early studies. Combinations of these agents are being evaluated. The future of the therapy of renal cancer appears promising owing to the efficacy of these novel agents.
The epidermal growth factor receptor (EGFR) is an established target for anti-cancer treatment in different tumour types. Two different strategies have been explored to inhibit this pivotal molecule in epithelial cancer development: small molecules TKIs and monoclonal antibodies. ErbB/HER-targeting by monoclonal antibodies such as cetuximab and trastuzumab or tyrosine-kinase inhibitors as gefitinib or erlotinib has been proven effective in the treatment of advanced NSCLC.
In this study we explored the potential of combining either erlotinib with cetuximab or trastuzumab to improve the efficacy of EGFR targeted therapy in EGFR wild-type NSCLC cell lines. Erlotinib treatment was observed to increase EGFR and/or HER2 expression at the plasma membrane level only in NSCLC cell lines sensitive to the drug inducing protein stabilization. The combined treatment had marginal effect on cell proliferation but markedly increased antibody-dependent, NK mediated, cytotoxicity in vitro. Moreover, in the Calu-3 xenograft model, the combination significantly inhibited tumour growth when compared with erlotinib and cetuximab alone.
Our results indicate that erlotinib increases surface expression of EGFR and/or HER2 only in EGFR-TKI sensitive NSCLC cell lines and, in turns, leads to increased susceptibility to ADCC both in vitro and in a xenograft models. The combination of erlotinib with monoclonal antibodies represents a potential strategy to improve the treatment of wild-type EGFR NSCLC patients sensitive to erlotinib.
Lung cancer; EGFR; Erlotinib; Cetuximab; ADCC
There are now a variety of therapies approved for the treatment of metastatic renal cell carcinoma (RCC). These include the immunotherapeutics, alfa-interferon, and interleukin-2, and agents that target the vascular endothelial growth factor receptor (VEGFR) via its tyrosine kinase, such as sorafenib, sunitinib, and pazopanib, or the mammalian target of rapamycin (mTOR), such as temsirolimus and everolimus. Bevacizumab, a monoclonal antibody directed against the ligand, VEGF, has shown activity against RCC as a single agent in patients who had failed prior cytokine therapy and as first line therapy in combination with interferon. The activity of bevacizumab in patients who had received and failed prior therapy has not been described. We report our experience in 4 patients with metastatic RCC who had failed prior cytokine, TKI, and mTOR inhibitors who were treated with bevacizumab as single agent therapy. These heavily pretreated patients sustained very prolonged periods of stable disease (median of 12 months) with very little toxicity and excellent quality of life. The activity of this agent in patients who had failed prior therapies directed against the VEGFR and mTOR suggests that therapy targeting the ligand, VEGF, is still a viable approach in these patients and deserves further study.
In this study, combination therapies using the oral fluoropyrimidine tegafur-gimeracil-oteracil (S-1) with several targeted agents or antibodies, were evaluated. First, the effects of tyrosine kinase inhibitors (erlotinib hydrochloride, sorafenib tosilate and sunitinib malate) against human non-small cell lung cancer (NSCLC), breast cancer and colorectal cancer were evaluated in vivo. The effects of the combination of S-1 and targeted antibodies (bevacizumab and cetuximab) against human colorectal cancers was also evaluated in vivo. S-1 and the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, erlotinib, showed a significant inhibition of growth in human NSCLC (Lu-99 and PC-9 cell lines). The antitumor activity of the combination of S-1 and erlotinib against Lu-99 and PC-9 cancer cell lines was significantly superior to either monotherapy (P<0.05). Combination therapy using the multi-tyrosine kinase inhibitors, sorafenib or sunitinib, with S-1 against breast cancer (MX-1 cell line) and NSCLC (NCI-H460 cell line) was significantly superior to either monotherapy (P<0.01). The combination of the anti-vascular endothelial growth factor antibody bevacizumab or the anti-EGFR antibody, cetuximab, with S-1 against human colorectal cancer [Col-1, KM20C (bevacizumab) and DLD-1 (cetuximab) cell lines] and a 5-fluorouracil (5-FU)-resistant cell line (KM12C/5-FU) was significantly superior to either monotherapy (p<0.01). In particular, the growth of the Col-1 cells was completely inhibited by the combination of S-1 and bevacizumab. No toxic mortalities and no significant difference in the body weight changes of the animals treated with S-1 combined with the targeted agents or with the mono-therapies were observed; therefore, the treatments appeared to be well-tolerated. Our preclinical findings indicate that the combination therapies of S-1 and targeted agents are promising treatment options.
S-1; combination chemotherapy; human tumor xenograft; targeted agents; growth delay period
Great strides have been made in improving the outcome of patients with metastatic colorectal cancer and targeted agents are an important part of the treatment arsenal. The approved monoclonal antibodies, bevacizumab, cetuximab and panitumumab, are part of the standard of care, yet only recently have we begun to define which patients benefit from these therapies using predictive tumor biomarkers. More recently, novel agents including aflibercept and regorafenib have had promising results and may become approved therapies. In addition, agents targeting the mTOR pathway and the TNF pathway have demonstrated early evidence of benefit. In the coming years, we may experience an influx of new therapies, possibly leading to further prolongation of patient survival or even, for some, a cure.
Bevacizumab is a monoclonal antibody that binds and neutralizes vascular endothelial growth factor (VEGF)-A, a key player in the angiogenesis pathway. Despite benefits of bevacizumab in cancer therapy, it is clear that the VEGF pathway is complex, involving multiple isoforms, receptors, and alternative ligands such as VEGF-B, and placental growth factor, which could enable escape from VEGF-A-targeted angiogenesis inhibition. Recently developed therapies have targeted other ligands in the VEGF pathway (eg, aflibercept, known as ziv-aflibercept in the United States), VEGF receptors (eg, ramucirumab), and their tyrosine kinase signaling (ie, tyrosine kinase inhibitors). The goal of the current review was to identify comparative preclinical data for the currently available VEGF-targeted therapies. Sources were compiled using PubMed searches (2007 to 2012), using search terms including, but not limited to: “bevacizumab,” “aflibercept,” “ramucirumab,” and “IMC-18F1.” Two preclinical studies were identified that compared bevacizumab and the newer agent, aflibercept. These studies identified some important differences in binding and pharmacodynamic activity, although the potential clinical relevance of these findings is not known. Newer antiangiogenesis therapies should help further expand treatment options for colorectal and other cancers. Comparative preclinical data on these agents is currently lacking.
aflibercept; antiangiogenesis; metastatic colorectal cancer (mCRC); tyrosine kinase inhibitor (TKI); vascular endothelial growth factor (VEGF)
Over the past decade, a multitude of targeted agents have been explored in the treatment of advanced non-small cell lung cancer (NSCLC). Thus far, two broad classes of agents have been implemented in clinical practice: (1) vascular endothelial growth factor (VEGF)-directed therapies and (2) antagonists of the epidermal growth factor receptor (EGFR). In the former category, the agent bevacizumab (a monoclonal antibody) has shown landmark improvements in survival when added to cytotoxic therapy. Small molecule tyrosine kinase inhibitors (TKIs) targeting the VEGF receptor (i.e., sunitinib, sorafenib, and vandetanib) show activity in phase II clinical studies. With respect to EGFR-directed therapies, the TKIs gefitinib and erlotinib have demonstrated significant benefit, and have uncovered valuable information regarding the biology of lung cancer. Outside of therapies directed specifically at VEGF- and EGFR-mediated signaling, trials evaluating insulin-like growth factor-1 receptor (IGF-IR)-targeting agents, cyclooxygenase-2 (COX-2) inhibitors, c-met inhibitors, irreversible pan-HER inhibitors, mammalian target of rapamycin (mTOR) inhibitors, and histone deacetylase (HDAC) inhibitors are ongoing. Inhibitors of ALK show great promise in patients with the relevant gene translocation. Herein, the clinical development of novel therapies for NSCLC is described, including some discussion of relevant biomarkers and determination of synergy with both cytotoxic therapy and other targeted agents.
Epidermal growth factor receptor (EGFR) inhibitors have introduced the concept of targeted therapy to the treatment of non-small cell lung cancer (NSCLC). These agents appear most effective in patients with tumors that are highly dependent on EGFR signaling pathways, a population that disproportionately includes females, nonsmokers, individuals of East Asian origin, and patients with adenocarcinoma histology. Currently available EGFR-inhibiting drugs include the tyrosine kinase inhibitors (TKIs) erlotinib, gefitinib, and lapatinib, which are administered orally and interfere with the intracellular tyrosine kinase domain, and the monoclonal antibodies (mAbs) cetuximab and panitumumab, which are administered intravenously and interfere with extracellular ligand binding. While the use of EGFR TKIs as monotherapy prolongs survival in metastatic NSCLC, they have demonstrated no benefit when added to conventional, cytotoxic chemotherapy. In contrast, the anti-EGFR mAb cetuximab appears most effective when combined with chemotherapy or radiation. Despite dramatic initial responses to treatment in some cases, NSCLC eventually becomes resistant to EGFR inhibition. Possible mechanisms include secondary mutations that interfere with drug binding, oncogenic pathways driven by other receptor tyrosine kinases, and independent activity of downstream signaling molecules. Efforts to overcome such resistance include irreversibly binding EGFR TKIs, multi-targeted TKIs, and combinations with chemotherapy, radiation, and other targeted therapies.
non-small cell lung cancer; epidermal growth factor receptor; monoclonal antibodies; tyrosine kinase inhibitors; targeted therapy
Renal cell carcinoma (RCC) accounts for approximately 3% of all cancers and is refractory to cytotoxic chemotherapy – immunotherapy has until recently been the standard of care for advanced disease. Randomised trials reported in the last 5 years have demonstrated that a number of agents including the monoclonal antibody, bevacizumab, and the kinase inhibitors – sorafenib sunitinib, temsirolimus and everolimus – are active in advanced RCC. Bevacizumab is directed against the vascular endothelial growth factor (VEGF), a key mediator of angiogenesis, whilst sorafenib and sunitinib inhibit a number of targets including the VEGF and platelet-derived growth factor (PDGFR) receptor tyrosine kinases. Temsirolimus and everolimus inhibit the intracellular mammalian target of rapamycin (mTOR) kinase. Sunitinib and temsirolimus have demonstrated efficacy in comparison with immunotherapy in the first-line setting in patients with favourable and poor prognosis advanced disease respectively. In the second-line setting, everolimus has shown benefit over placebo in patients who progress following treatment with a VEGF receptor tyrosine kinase inhibitor and sorafenib has demonstrated efficacy in comparison with placebo in patients with immunotherapy-refractory disease. We review here recent clinical trial data and discuss future developments in the systemic treatment of RCC including combination and sequential therapy, adjuvant therapy, the role of biomarkers and the prospects for the development of rational mechanism-directed therapy in this disease.
renal cell carcinoma; bevacizumab; sorafenib; sunitinib; temsirolimus; everolimus
The incidence of esophagogastric cancers is increasing rapidly in the Western population. Despite better understanding of the biology and intense research in the treatment of these cancers, the long-term survival remains poor both in the locally advanced and metastatic settings. The addition of combined modality strategies has resulted in modest improvement in 5-year survival rates. A number of biologic agents targeting epidermal-derived growth factor receptor, vascular endothelial derived growth factor and its receptor, and mammalian target of rapamycin (mTOR) are being currently evaluated in Phase II and III clinical trials. Some of these, like trastuzumab, cetuximab, and bevacizumab, have shown promising results. This review provides a brief overview of the recent developments in biologic agents for the treatment of esophagogastric cancers.
adenocarcinoma; squamous cell carcinoma; VEGF; trastuzumab; Her2-positive EGC
The therapeutic options in metastatic renal cell carcinoma have been recently expanded by the discovery of the VHL gene, the mutation of which is associated with development of clear cell carcinoma, and overexpression of the angiogenesis pathway, resulting in a very vascular tumor. This breakthrough in science led to the development of a variety of small molecules inhibiting the VEGF-dependent angiogenic pathway, such as sunitinib and sorafenib. These agents prolong overall and progression-free survival, respectively. The result was the development of robust front-line therapies which ultimately fail and are associated with disease progression. In this setting, there existed an unmet need for developing second-line therapies for patients with refractory metastatic renal cell carcinoma (MRCC). Everolimus (RAD 001) is an oral inhibitor of the mammalian target of rapamycin (mTOR) pathway. The double-blind, randomized, placebo-controlled phase III trial of everolimus (RECORD-1) conducted in MRCC patients after progression on sunitinib or sorafenib, or both, demonstrated a progression-free survival benefit favoring the study drug (4.9 months vs 1.9 months, HR 0.33, 95% CI 0.25 to 0.43, P ≤ 0 0.001). Everolimus thus established itself as a standard of care in the second-line setting for patients with MRCC who have failed treatment with VEGF receptor inhibitors.
mTOR inhibitor; mammalian target of rapamycin inhibitor; signal transduction inhibitor; renal cell carcinoma; targeted therapy
Agents targeting the vascular endothelial growth factor (VEGF) pathway are being used with increasing frequency in patients with recurrent high-grade glioma. The effect of more than one antiangiogenic therapy given in succession has not been established. We reviewed the efficacy of bevacizumab, a VEGF-A monoclonal antibody, in patients who progressed following prior therapy with VEGF receptor tyrosine kinase inhibitors (R-TKi). Seventy-three patients with recurrent high-grade gliomas received VEGF R-TKi (cediranib, sorafenib, pazopanib, or sunitinib) as part of phase I or II clinical trials. Twenty-four of these patients with glioblastoma progressed and received bevacizumab-containing regimens immediately after R-TKi. Those who stopped R-TKi therapy for reasons other than disease progression, or received a treatment that did not include bevacizumab, were excluded from the analysis. The efficacy of bevacizumab-containing regimens in these 24 patients was evaluated. During R-TKi therapy, 6 of 24 patients (25%) had a partial response (PR) to treatment. The 6-month progression-free survival (APF6) was 16.7% and median time-to-progression (TTP) was 14.3 weeks. Grade III/IV toxicities were seen in 13 of 24 patients (54%). Subsequently with bevacizumab salvage therapy, 5 of 24 patients (21%) had a PR, the APF6 was 12.5%, and the median TTP was 8 weeks. Five of 24 patients had grade III/IV toxicities (21%). The median overall survival (OS) from the start of R-TKi therapy was 9.2 months (range: 2.8–34.1+), whereas the median OS after bevacizumab was 5.2 months (range: 1.3–28.9+). Bevacizumab retains modest activity in high-grade glioma patients who progress on R-TKi. However, the APF6 of 12.5% in this cohort of patients indicates that durable tumor control is not achieved for most patients.
bevacizumab; recurrent glioblastoma; tyrosine kinase inhibitor; vascular endothelial growth factor.
Cetuximab is an epidermal growth factor receptor (EGFR)-blocking antibody that is approved to treat several types of solid cancers in patients. We recently showed that cetuximab can induce autophagy in cancer cells by both inhibiting the class I phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway and activating the class III PI3K (hVps34)/beclin 1 pathway. In the current study, we investigated the relationship between cetuximab-induced autophagy and apoptosis and the biological roles of autophagy in cetuximab-mediated cancer therapy. We found that cetuximab induced autophagy in cancer cells that show strong or weak induction of apoptosis after cetuximab treatment but not in those that show only cytostatic growth inhibition. Inhibition of cetuximab-induced apoptosis by a caspase inhibitor prevented the induction of autophagy. Conversely, inhibition of cetuximab-induced autophagy by silencing the expression of autophagy-related genes (Atg) or treating the cancer cells with lysosomal inhibitors enhanced the cetuximab-induced apoptosis, suggesting that autophagy was a protective cellular response to cetuximab treatment. On the other hand, cotreatment of cancer cells with cetuximab and the mTOR inhibitor rapamycin resulted in an Atg-dependent and lysosomal inhibition-sensitive death of cancer cells that show only growth inhibition or weak apoptosis after cetuximab treatment, indicating that cell death may be achieved by activating the autophagy pathway in these cells. Together, our findings may guide the development of novel clinical strategies for sensitizing cancer cells to EGFR-targeted therapy.
EGFR; cetuximab; autophagy; apoptosis; cancer therapy
Cetuximab is an epidermal growth factor receptor (EGFR)-blocking antibody that is approved to treat several types of solid cancers in patients. We recently showed that cetuximab can induce autophagy in cancer cells by both inhibiting the class I phosphatidylinositol 3-kinase (PtdIns3K)/Akt/mammalian target of rapamycin (mTOR) pathway and activating the class III PtdIns3K (hVps34)/beclin 1 pathway. In the current study, we investigated the relationship between cetuximab-induced autophagy and apoptosis and the biological roles of autophagy in cetuximab-mediated cancer therapy. We found that cetuximab induced autophagy in cancer cells that show strong or weak induction of apoptosis after cetuximab treatment but not in those that show only cytostatic growth inhibition. Inhibition of cetuximab-induced apoptosis by a caspase inhibitor prevented the induction of autophagy. Conversely, inhibition of cetuximab-induced autophagy by silencing the expression of autophagy-related genes (Atg) or treating the cancer cells with lysosomal inhibitors enhanced the cetuximab-induced apoptosis, suggesting that autophagy was a protective cellular response to cetuximab treatment. On the other hand, cotreatment of cancer cells with cetuximab and the mTOR inhibitor rapamycin resulted in an Atg-dependent and lysosomal inhibition-sensitive death of cancer cells that show only growth inhibition or weak apoptosis after cetuximab treatment, indicating that cell death may be achieved by activating the autophagy pathway in these cells. Together, our findings may guide the development of novel clinical strategies for sensitizing cancer cells to EGFR-targeted therapy.
EGFR; cetuximab; autophagy; apoptosis; cancer therapy