Showing papers in "Nature Reviews Clinical Oncology in 2010"

Delivering nanomedicine to solid tumors

Abstract: Recent advances in nanotechnology have offered new hope for cancer detection, prevention, and treatment. While the enhanced permeability and retention effect has served as a key rationale for using nanoparticles to treat solid tumors, it does not enable uniform delivery of these particles to all regions of tumors in sufficient quantities. This heterogeneous distribution of therapeutics is a result of physiological barriers presented by the abnormal tumor vasculature and interstitial matrix. These barriers are likely to be responsible for the modest survival benefit offered by many FDA-approved nanotherapeutics and must be overcome for the promise of nanomedicine in patients to be realized. Here, we review these barriers to the delivery of cancer therapeutics and summarize strategies that have been developed to overcome these barriers. Finally, we discuss design considerations for optimizing the delivery of nanoparticles to tumors.

Triple-negative breast cancer: disease entity or title of convenience?

Abstract: This Review outlines the understanding and management of triple-negative breast cancer (TNBC). TNBC shares morphological and genetic abnormalities with basal-like breast cancer (BLBC), a subgroup of breast cancer defined by gene-expression profiling. However, TNBC and BLBC tumors are heterogeneous and overlap is incomplete. Breast cancers found in BRCA1 mutation carriers are also frequently triple negative and basal like. TNBC and BLBC occur most frequently in young women, especially African Americans, and tend to exhibit aggressive, metastatic behavior. These tumors respond to conventional chemotherapy but relapse more frequently than hormone receptor-positive, luminal subtypes and have a worse prognosis. New systemic therapies are urgently needed as most patients with TNBC and/or BLBC relapse with distant metastases, and hormonal therapies and HER2-targeted agents are ineffective in this group of tumors. Poly (ADP-ribose) polymerase inhibitors, angiogenesis inhibitors, EGFR-targeted agents, and src kinase and mTOR inhibitors are among the therapeutic agents being actively investigated in clinical trials in patients with TNBC and/or BRCA1-associated tumors. Increased understanding of the genetic abnormalities involved in the pathogenesis of TNBC, BLBC and BRCA1-associated tumors is opening up new therapeutic possibilities for these hard-to-treat breast cancers.

Microsatellite instability in colorectal cancer—the stable evidence

Abstract: Microsatellite instability (MSI) is the molecular fingerprint of a deficient mismatch repair system. Approximately 15% of colorectal cancers (CRC) display MSI owing either to epigenetic silencing of MLH1 or a germline mutation in one of the mismatch repair genes MLH1, MSH2, MSH6 or PMS2. Methods to detect MSI are well established and routinely incorporated into clinical practice. A clinical and molecular profile of MSI tumors has been described, leading to the concept of an MSI phenotype in CRC. Studies have confirmed that MSI tumors have a better prognosis than microsatellite stable CRC, but MSI cancers do not necessarily have the same response to the chemotherapeutic strategies used to treat microsatellite stable tumors. Specifically, stage II MSI tumors might not benefit from 5-fluorouracil-based adjuvant chemotherapy regimens. New data suggest possible advantages of irinotecan-based regimens, but these findings require further clarification. Characterization of the molecular basis of MSI in CRC is underway and initial results show that mutations in genes encoding kinases and candidate genes with microsatellite tracts are over-represented in MSI tumors. Transcriptome expression profiles of MSI tumors and systems biology approaches are providing the opportunity to develop targeted therapeutics for MSI CRC.

Advanced pancreatic carcinoma: current treatment and future challenges.

Abstract: Pancreatic adenocarcinoma is the most lethal of the solid tumors and the fourth leading cause of cancer-related death in North America. Most patients present with locally advanced or metastatic disease that precludes curative resection. These patients have an extremely poor prognosis. In the absence of effective screening methods, considerable efforts have been made during the past decade to identify better systemic treatments. Unfortunately most trials have not shown a survival advantage for most therapies. In tandem with this increased clinical research, there has also been an expansion of preclinical laboratory investigation. These preclinical studies revealed many of the molecular mechanisms involved in pancreatic cancer development, which has provided insights into why current therapies are ineffective. These new discoveries provide some optimism that new agents inhibiting specific targets will improve outcome and overcome the resistance of pancreatic cancer to most standard treatments. We review the current standards of care for patients with locally advanced and metastatic pancreatic carcinoma and outline some future directions for the development of new treatment strategies.

Charged particles in radiation oncology

Abstract: Radiotherapy is one of the most common and effective therapies for cancer. Generally, patients are treated with X-rays produced by electron accelerators. Many years ago, researchers proposed that high-energy charged particles could be used for this purpose, owing to their physical and radiobiological advantages compared with X-rays. Particle therapy is an emerging technique in radiotherapy. Protons and carbon ions have been used for treating many different solid cancers, and several new centers with large accelerators are under construction. Debate continues on the cost:benefit ratio of this technique, that is, on whether the high costs of accelerators and beam delivery in particle therapy are justified by a clear clinical advantage. This Review considers the present clinical results in the field, and identifies and discusses the research questions that have resulted with this technique.

Understanding resistance to EGFR inhibitors-impact on future treatment strategies.

Abstract: EGFR is a tyrosine kinase that participates in the regulation of cellular homeostasis. Following ligand binding, EGFR stimulates downstream cell signaling cascades that influence cell proliferation, apoptosis, migration, survival and complex processes, including angiogenesis and tumorigenesis. EGFR has been strongly implicated in the biology of human epithelial malignancies, with therapeutic applications in cancers of the colon, head and neck, lung, and pancreas. Accordingly, targeting EGFR has been intensely pursued, with the development of a series of promising molecular inhibitors for use in clinical oncology. As is common in cancer therapy, challenges with respect to treatment resistance emerge over time. This situation is certainly true of EGFR inhibitor therapies, where intrinsic and acquired resistance is now well recognized. In this Review, we provide a brief overview regarding the biology of EGFR, preclinical and clinical development of EGFR inhibitors, and molecular mechanisms that underlie the development of treatment resistance. A greater understanding of the mechanisms that lead to EGFR resistance may provide valuable insights to help design new strategies that will enhance the impact of this promising class of inhibitors for the treatment of cancer.

Metronomic chemotherapy: new rationale for new directions.

Abstract: Tumor angiogenesis is recognized as a major therapeutic target in the fight against cancer. The key involvement of angiogenesis in tumor growth and metastasis has started to redefine chemotherapy and new protocols have emerged. Metronomic chemotherapy, which is intended to prevent tumor angiogenesis, is based on more frequent and low-dose drug administrations compared with conventional chemotherapy. The potential of metronomic chemotherapy was revealed in animal models a decade ago and the efficacy of this approach has been confirmed in the clinic. In the past 5 years, multiple clinical trials have investigated the safety and efficacy of metronomic chemotherapy in a variety of human cancers. While the results have been variable, clinical studies have shown that these new treatment protocols represent an interesting alternative for either primary systemic therapy or maintenance therapy. We review the latest clinical trials of metronomic chemotherapy in adult and pediatric cancer patients. Accumulating evidence suggests that the efficacy of such treatment may not only rely on anti-angiogenic activity. Potential new mechanisms of action, such as restoration of anticancer immune response and induction of tumor dormancy are discussed. Finally, we highlight the research efforts that need to be made to facilitate the optimal development of metronomic chemotherapy.

mTOR signaling and drug development in cancer

Abstract: Mammalian target of rapamycin (mTOR) is a protein kinase of the PI3K/Akt signaling pathway. Activation of mTOR in response to growth, nutrient and energy signals leads to an increase in protein synthesis, which is required for tumor development. This feature makes mTOR an attractive target for cancer therapy. First-generation mTOR inhibitors are sirolimus derivatives (rapalogs), which have been evaluated extensively in cancer patients. Everolimus and temsirolimus are already approved for the treatment of renal-cell carcinoma. Temsirolimus is also approved for the treatment of mantle-cell lymphoma. These drugs, in addition to ridaforolimus (formerly deforolimus) and sirolimus, are currently being evaluated in clinical trials of various cancers. Second-generation mTOR inhibitors are small molecules that target the kinase domain, and have also entered clinical development. Clinical trials are underway to identify additional malignancies that respond to mTOR inhibitors, either alone or in combination with other therapies. Future research should evaluate the optimal drug regimens, schedules, patient populations, and combination strategies for this novel class of agents.

Stereotactic body radiation therapy: A novel treatment modality

Abstract: Stereotactic body radiation therapy has emerged as a novel cancer therapy in the past 10–15 years This review article gives an overview of the background, radiobiologic, technical and clinical aspects of stereotactic body radiation therapy. Stereotactic body radiation therapy (SBRT) involves the delivery of a small number of ultra-high doses of radiation to a target volume using very advanced technology and has emerged as a novel treatment modality for cancer. The role of SBRT is most important at two cancer stages—in early primary cancer and in oligometastatic disease. This modality has been used in the treatment of early-stage non-small-cell lung cancer, prostate cancer, renal-cell carcinoma, and liver cancer, and in the treatment of oligometastases in the lung, liver, and spine. A large body of evidence on the use of SBRT for the treatment of primary and metastatic tumors in various sites has accumulated over the past 10–15 years, and efficacy and safety have been demonstrated. Several prospective clinical trials of SBRT for various sites have been conducted, and several other trials are currently being planned. The results of these clinical trials will better define the role of SBRT in cancer management. This article will review the radiobiologic, technical, and clinical aspects of SBRT.

Biomarkers and surrogate end points—the challenge of statistical validation

Abstract: Biomarkers and surrogate end points have great potential for use in clinical oncology, but their statistical validation presents major challenges, and few biomarkers have been robustly confirmed. Provisional supportive data for prognostic biomarkers, which predict the likely outcome independently of treatment, is possible through small retrospective studies, but it has proved more difficult to achieve robust multi-site validation. Predictive biomarkers, which predict the likely response of patients to specific treatments, require more extensive data for validation, specifically large randomized clinical trials and meta-analysis. Surrogate end points are even more challenging to validate, and require data demonstrating both that the surrogate is prognostic for the true end point independently of treatment, and that the effect of treatment on the surrogate reliably predicts its effect on the true end point. In this Review, we discuss the nature of prognostic and predictive biomarkers and surrogate end points, and examine the statistical techniques and designs required for their validation. In cases where the statistical requirements for validation cannot be rigorously achieved, the biological plausibility of an end point or surrogate might support its adoption. No consensus yet exists on processes or standards for pragmatic evaluation and adoption of biomarkers and surrogate end points in the absence of robust statistical validation.

The molecular pathology of cancer.

Abstract: Rapid technical advances in DNA sequencing and genome-wide association studies are driving the discovery of the germline and somatic mutations that are present in different cancers. Mutations in genes involved in cellular signaling are common, and often shared by tumors that arise in distinct anatomical locations. Here we review the most important molecular changes in different cancers from the perspective of what should be analyzed on a routine basis in the clinic. The paradigms are EGFR mutations in adenocarcinoma of the lung that can be treated with gefitinib, KRAS mutations in colon cancer with respect to treatment with EGFR antibodies, and the use of gene-expression analysis for ER-positive, node-negative breast cancer patients with respect to chemotherapy options. Several other examples in both solid and hematological cancers are also provided. We focus on how disease subtypes can influence therapy and discuss the implications of the impending molecular diagnostic revolution from the point of view of the patients, clinicians, and the diagnostic and pharmaceutical companies. This paradigm shift is occurring first in cancer patient management and is likely to promote the application of these technologies to other diseases.

Targeted therapy in non-small-cell lung cancer—is it becoming a reality?

Abstract: Treatment outcomes in advanced or metastatic non-small-cell lung cancer (NSCLC) remain unsatisfactory, with low long-term survival rates. Palliative chemotherapy offers a median survival not exceeding 1 year. To date, various combinations of cytotoxic drugs have not improved treatment results beyond what has been observed with platinum doublets. By contrast, molecular targeted drugs may block important pathways that drive cancer progression and achieve long-term disease control. Conflicting results have demonstrated marginal benefit with EGFR inhibitors, anti-EGFR monoclonal antibodies and antiangiogenic strategies in unselected populations of patients with advanced NSCLC. However, patients with an EGFR mutation are likely to respond to agents that target this gene. Novel targeted therapies that interfere with insulin-like growth factor 1 receptor, or the EML4-ALK fusion protein have shown promising activity. Aberrations in other key signaling pathways and molecules, such as RAS/RAF/MEK, PI3K/AKT/mTOR, or MET kinase, have been identified as crucial targets, especially in resistant patients. Novel drugs aimed at these abnormalities are already in the clinic. This Review outlines the current state-of-the-art research for targeted therapy in NSCLC.

Molecular mechanisms of metastasis in breast cancer--clinical applications

Abstract: The metastatic cascade is a series of biological processes that enable the movement of tumor cells from the primary site to a distant location and the establishment of a new cancer growth. Circulating tumor cells (CTCs) have a crucial role in tumor dissemination. The role of CTCs in treatment failure and disease progression can be explained by their relation to biological processes, including the epithelial-to-mesenchymal transition and 'self seeding', defined as reinfiltration of the primary tumor or established metastasis by more aggressive CTCs. CTCs are a unique and heterogeneous cell population with established prognostic and predictive value in certain clinical situations. The possibility of collecting sequential blood samples for real-time monitoring of systemic-therapy efficacy presents new possibilities to evaluate targeted therapies based on the genomic profiling of CTCs and to improve the clinical management of patients by personalized therapy. Interruption of the metastatic cascade via the targeting of CTCs might be a promising therapeutic strategy.

Mismatch repair deficient colorectal cancer in the era of personalized treatment

Abstract: The molecular and genetic subtyping of cancer has allowed the emergence of individualized therapies. This approach could potentially deliver treatments that have both increased efficacy as well as reduced toxicity. A well-defined subtype of colorectal cancer (CRC) is characterized by a deficiency in the mismatch repair (MMR) pathway. MMR deficiency not only contributes to the pathogenesis of a large proportion of CRC, but also determines the response to many of the drugs that are frequently used to treat this disease. In this Review we describe the MMR deficient phenotype and discuss how a deficiency in this DNA repair process may impact on the management of CRC, including surgery, adjuvant chemotherapy and the choice of systemic agents for the palliation of advanced disease. We also discuss how the DNA repair defect in MMR deficient CRC could be exploited in the development of novel therapeutic strategies.

Conscripts of the infinite armada: systemic cancer therapy using nanomaterials

Abstract: The field of clinical nanomaterials is enlarging steadily, with more than a billion US dollars of funding allocated to research by US government agencies in the past decade. The first generation of anti-cancer agents using novel nanomaterials has successfully entered widespread use. Newer nanomaterials are garnering increasing interest as potential multifunctional therapeutic agents; these drugs are conferred novel properties, by virtue of their size and shape. The new features of these agents could potentially allow increased cancer selectivity, changes in pharmacokinetics, amplification of cytotoxic effects, and simultaneous imaging capabilities. After attachment to cancer target reactive-ligands, which interact with cell-surface antigens or receptors, these new constructs can deliver cytolytic and imaging payloads. The molecules also introduce new challenges for drug development. While nanoscale molecules are of a similar size to proteins, the paradigms for how cells, tissues and organs of the body react to the non-biological materials are not well understood, because most cellular and metabolic processes have evolved to deal with globular, enzyme degradable molecules. We discuss examples of different materials to illustrate interesting principles for development and future applications of these nanomaterial medicines with emphasis on the possible pharmacologic and safety hurdles for accomplishing therapeutic goals.

Molecular predictors of response to trastuzumab and lapatinib in breast cancer

Abstract: Trastuzumab is a monoclonal antibody directed against the human EGFR2 (HER2) protein that has been shown to improve survival in patients with HER2-positive breast cancer. Lapatinib is an oral small-molecule tyrosine kinase inhibitor directed against EGFR and HER2. Lapatinib therapy was shown to prolong the time to progression and increase the rate of response to capecitabine in patients who had received anthracycline-based and taxane-based chemotherapy, and whose tumors had progressed on trastuzumab. HER2 status, either gene copy number or the protein expression level, is the best predictive marker available for assessing response to trastuzumab and lapatinib. Whether the power of this predictive marker is the same in advanced and early-stage cancers is unknown. There is great interest in developing diagnostic tests that predict which patients are more likely to benefit from specific HER2-directed therapies. Novel therapeutics that will overcome resistance to trastuzumab and lapatinib are under intense clinical development. In the future, it will be important to characterize mechanisms of resistance in metastatic tumors to determine which novel targeted therapy will be most appropriate for individual patients.

The Oncofertility Consortium—addressing fertility in young people with cancer

Abstract: The number of young cancer survivors is increasing owing to advances in cancer therapeutics, but many face infertility as a result of their treatment. Technologies that already exist for cancer patients concerned about their future fertility include sperm banking for men and hormonal intervention followed by in vitro fertilization and embryo cryopreservation for women. However, logistical barriers to timely patient referral and coordination of care between specialties can limit patient access to all the available options. Moreover, there are few alternatives for young women and girls who cannot delay their cancer treatment, or who are unable to undergo hormonal intervention. The Oncofertility Consortium is a network of researchers, physicians and scholars who are advancing fertility preservation options for young cancer patients. Research into the societal, ethical, and legal implications is also an important part of the work performed by the Oncofertility Consortium, which is providing new perspectives on patient decision-making about how to access these emerging reproductive technologies. Experts in the fields of oncology, reproductive medicine, the social sciences, law, education, and the humanities are working together to develop next-generation reproductive interventions and promote communication between scholars, clinicians, patients, and the public to ensure that young cancer patients are equipped with the most appropriate information and options for having a family in the future.

Gene-expression-based prognostic assays for breast cancer.

Abstract: Several gene-expression-based reference laboratory tests are now available for prognostication of patients diagnosed with breast cancer. For clinical oncologists, it is important to understand the clinical contexts for which these assays were developed in order to use them properly. This Review is aimed at providing a conceptual and technical overview of the steps involved in the development of gene-expression profiling-based prognostic assays. MammaPrint and Oncotype DX, two widely utilized assays, are compared with respect to differences in the clinical contexts for their development, technologies used, and clinical utilities with the aim of providing a guide to clinical oncologists for utilization of these assays.

Management of breast cancer with targeted agents: importance of heterogenicity

Abstract: Breast cancer is a heterogeneous disease with different molecular drivers regulating its growth, survival and treatment response. Drug development efforts have resulted in agents against new molecular targets that are active against only those tumors with the targeted molecular alteration or phenotype. The authors critically discuss the recently established and investigational strategies for the treatment of the main breast cancer subtypes. Breast cancer is a heterogeneous disease with different molecular drivers regulating its growth, survival and response to therapy. Breast cancer is divided in three major subtypes based on the pattern of expression of hormone receptors and HER2: luminal tumors (or HR positive), HER2 amplified tumors, and the remaining subtypes being collectively referred to as triple-negative breast cancer. While tumors within these subtypes have similar gene-expression patterns, clinical outcomes, and response to therapy, this division is far from perfect and subgroups within these groups are beginning to be identified. In terms of therapy, an increasingly rational drug development effort has resulted in agents against new molecular targets that are active against only those tumors with the targeted molecular alteration or phenotype. These agents include receptor and non-receptor tyrosine kinase inhibitors (HER1, HER2, HER3, insulin-like growth factor receptor, c-met, fibroblast growth factor receptor and HSP 90 inhibitors), intracellular signaling pathways (PI3K, AKT, mTOR), angiogenesis inhibitors and agents that interfere with DNA repair (PARP inhibitors). Thus, the overall management of breast cancer will increasingly require an understanding of breast cancer heterogeneicity, the biological nature of any given tumor as well the existence of increased personalized treatment options.

Intraperitoneal therapy for peritoneal tumors: biophysics and clinical evidence

Abstract: In patients with tumors confined to the peritoneal cavity, there is established pharmacokinetic and tumor biology-related evidence that intraperitoneal drug administration is advantageous. Three large randomized trials in patients with stage III ovarian cancer who underwent optimal cytoreduction have demonstrated a significant survival benefit when intraperitoneal chemotherapy was added to systemic therapy. Although intraperitoneal therapy is associated with locoregional toxic effects, recent trials suggest that with some modification of the local delivery methods this approach is safe in 80% of patients in an ambulatory setting. Surgical cytoreduction immediately followed by intraoperative hyperthermic intraperitoneal chemoperfusion (HIPEC) ensures intraperitoneal delivery of the drug to all peritoneal surfaces and the advantages of combined hyperthermia to be exploited. An increasing number of centers are initiating this multimodality therapy in ovarian cancer and colorectal cancer. Clearly, intraperitoneal drug delivery is an important adjunct to surgery and systemic chemotherapy in selected patients. The optimal drug, dose and schedule for intraperitoneal delivery, the exact role of added HIPEC compared with cytoreduction alone, and the potential role of HIPEC in ovarian cancer and peritoneal mesothelioma are still undefined. Several randomized controlled trials addressing these uncertainties have been initiated.

BRCA mutations in the management of breast cancer: the state of the art.

Abstract: Genetic testing for BRCA1 and BRCA2 mutations is gaining acceptance in clinical oncology worldwide and may help target unaffected high-risk women for prevention and for close surveillance. Annual screening with MRI seems to be an effective surveillance strategy, but the long term follow-up of women with small MRI-detected breast cancers is necessary to establish its ultimate value. Women with cancer and a BRCA mutation may benefit from tailored treatments, such as cisplatin or olaparib. The treatment goals for a woman with a BRCA-associated breast cancer should be to prevent recurrence of the initial cancer and to prevent second primary breast and ovarian cancers. Mutations in BRCA1 and BRCA2 are presented throughout the world and it is important that the benefits of genetic testing and of targeted therapies be extended to women who live outside of North America and Western Europe.

Alterations in VHL as potential biomarkers in renal-cell carcinoma

Abstract: Germ line mutations in the VHL tumor-suppressor gene cause von Hippel-Lindau (VHL) disease, a hereditary neoplastic disease associated with clear-cell renal-cell carcinomas (ccRCCs), central nervous system hemangioblastomas and pheochromocytomas. Disruption of VHL, by somatic mutation, hypermethylation of its promoter or chromosomal loss, is also seen in the majority of cases of sporadic ccRCC. The protein product of VHL, pVHL, has multiple functions, the best-documented of which relates to its ability to target hypoxia-inducible factors (HIFs) for polyubiquitination and proteasomal degradation through its role in substrate recognition as part of a ubiquitin ligase complex. Consequently, pVHL-defective ccRCCs overexpress mRNAs that are under the transcriptional control of HIF. Drugs that modulate the downstream targets of the pVHL/HIF pathway, including sunitinib, sorafenib, temsirolimus and bevacizumab, have proven benefit in treating ccRCC. In VHL disease, clear evidence supports strong genotype-phenotype correlations, but the situation in sporadic ccRCC is less clear. Data indicate that VHL alterations have a potential role as prognostic and predictive markers in ccRCC. Future clinical trials should prospectively define the VHL alteration status of study participants so that the true utility of such markers can be determined.

Imaging ovarian cancer and peritoneal metastases—current and emerging techniques

Abstract: Peritoneal metastases are often the first presentation of ovarian malignancy. Evaluating the extent of disease critically determines tumor resectability and can also predict outcome. Standard CT, however, frequently fails to identify small sites of peritoneal spread. Moreover, it does not provide a quantitative index of disease response to cytotoxic therapy as it relies on macroscopic morphological changes in tumor volume, and does not reflect preceding molecular events in the microenvironment of the tumor. We describe the emerging role of functional imaging techniques, such as radioimmunoscintigraphy, PET/CT, diffusion-weighted MRI, dynamic contrast-enhanced MRI, and magnetic resonance spectroscopy in staging ovarian cancer and assessing treatment response. The combination of functional information with conventional anatomical visualization holds promise to accurately characterize peritoneal disease, and provides noninvasive biomarkers of therapeutic performance and patient prognosis.

Tumor size and survival in breast cancer--a reappraisal.

Abstract: The size of a breast cancer at diagnosis has conventionally been thought of as a fundamental and critical determinant of clinical outcome. However, the tendency of some subtypes of breast cancer to behave aggressively, despite being small (

The role of radiotherapy for metastatic epidural spinal cord compression.

Abstract: Radiotherapy alone is the most common treatment for metastatic epidural spinal cord compression (MESCC). Decompressive surgery followed by radiotherapy is generally indicated only in 10-15% of MESCC cases. Chemotherapy has an unclear role and may be considered for selected patients with hematological or germ-cell malignancies. If radiotherapy alone is given, it is important to select the appropriate regimen. Similar functional outcomes can be achieved with short-course radiotherapy regimens and longer-course radiotherapy regimens. Longer-course radiotherapy is associated with better local control of MESCC than short-course radiotherapy. Patients with a more favorable survival prognosis (expected survival of ≥6 months) should receive longer-course radiotherapy, as they may live long enough to develop a recurrence of MESCC. Patients with an expected survival of <6 months should be considered for short-course radiotherapy. A recurrence of MESCC in the previously irradiated region after short-course radiotherapy may be treated with another short-course of radiotherapy. After primary administration of longer-course radiotherapy, decompressive surgery should be performed if indicated. Alternatively, re-irradiation can be performed using high-precision techniques to reduce the cumulative dose received by the spinal cord. Larger prospective trials are required to better define the appropriate treatment for the individual patient.

Future directions of bone-targeted therapy for metastatic breast cancer

Abstract: Bone is the most common metastatic site for breast cancer, and bone metastases can cause pain as well as risk of pathological fractures. Emerging treatments for metastatic bone disease have arisen from advances in our understanding of the unique cellular and molecular mechanisms that contribute to bone metastasis. The interaction between tumor cells and the bone microenvironment results in a 'vicious cycle' that increases both bone destruction and tumor burden. The tumor secretes factors, such as parathyroid hormone-related peptide, that stimulate osteoclastogenesis. Similarly, the bone stroma produces growth factors, such as transforming growth factor β, that promote tumor growth in bone. Therapeutic targeting of these microenvironmental factors is under intensive investigation. Other attractive therapeutic targets include signaling molecules, such as receptor activator of nuclear factor κB ligand, Src kinase, and cathepsin K, all of which regulate osteoclast function, and chemokine receptor 4, which is involved in the homing of tumor cells to bone. In this Review, we describe the progress and future directions of novel bone-targeted therapies that may reduce or prevent destructive bone metastasis from breast cancer. Novel modalities for predicting and monitoring treatment response will also be described.

Making the best of PARP inhibitors in ovarian cancer

Abstract: Drugs that inhibit the enzyme poly(ADP-ribose)polymerase (PARP) are showing considerable promise for the treatment of cancers that have mutations in the BRCA1 or BRCA2 tumor suppressors. This therapeutic approach exploits a synthetic lethal strategy to target the specific DNA repair pathway in these tumors. High-grade ovarian cancers have a generally poor prognosis, and accumulating evidence suggests that mutations in BRCA1 or BRCA2, or silencing of BRCA1 by promoter methylation, may be common in this disease. Here, we consider how the potential benefit of PARP inhibitors might be maximized in ovarian cancer. We suggest that it will be crucial to explore novel therapeutic trial strategies and drug combinations, and incorporate robust biomarkers predictive of response if these drugs are to reach their full potential.

Taxanes: optimizing adjuvant chemotherapy for early-stage breast cancer

Abstract: Taxanes are among the most widely used chemotherapy agents for advanced breast cancer. Results are now available from 21 trials that randomly allocated nearly 36,000 women with early-stage breast cancer to receive first-generation taxane-based adjuvant chemotherapy versus non-taxane-based adjuvant regimens. Three recent meta-analyses suggest that taxanes are beneficial in the adjuvant setting, irrespective of the patient's age, lymph-node involvement, hormone-receptor expression, and HER2 status. Nevertheless, the optimal role for taxanes in the adjuvant management of early-stage breast cancer remains controversial. We review the results of the first-generation taxane trials and discuss possible explanations for the differences observed in these studies, including variation in the 'strength' of anthracycline therapy in the control arms; suboptimal timing, dosing, or schedule of the taxane regimen; a masking effect of trials that included patients with relatively chemotherapy-insensitive luminal A disease; and decreased representation of the putative taxane-sensitive disease subset. Inclusion criteria for future clinical trials must be revised to account for the molecular heterogeneity of breast cancer and further optimize the role of adjuvant taxane therapy in early-stage disease.

What should physicians look for in evaluating prognostic gene-expression signatures?

Abstract: Well-developed and validated genomic signatures can lead to personalized treatment decisions resulting in improved patient management. However, the pace of acceptance of these signatures in clinical practice has been slow because many of the signatures have been developed without clear focus on the intended clinical use, and proper independent validation studies establishing their medical utility have rarely been performed. The authors of this Review focus on guidelines that physicians could refer to when evaluating studies on prognostic gene-expression signatures. Most cancer treatments benefit only a minority of patients. This has led to a widespread interest in the identification of gene-expression-based prognostic signatures. Well-developed and validated genomic signatures can lead to personalized treatment decisions resulting in improved patient management. However, the pace of acceptance of these signatures in clinical practice has been slow. This is because many of the signatures have been developed without clear focus on the intended clinical use, and proper independent validation studies establishing their medical utility have rarely been performed. The practicing physician and the patient are thus left in doubt about the reliability and medical utility of the signatures. We aim to provide guidance to physicians in critically evaluating published studies on prognostic gene-expression signatures so that they are better equipped to decide which signatures, if any, have sufficient merit for use, in conjunction with other factors in helping their patients to make good treatment decisions. A discussion of the lessons to be learned from the successful development of the Oncotype DX® genetic test for breast cancer is presented and contrasted with a review of the current status of prognostic gene-expression signatures in non-small-cell lung cancer.