Utility of clinical and MR imaging parameters for prediction and monitoring of response to capecitabine and temozolomide (CAPTEM) therapy in patients with liver metastases of neuroendocrine tumors

BACKGROUND

This study explores the predictive and monitoring capabilities of clinical and multiparametric MR parameters in assessing capecitabine and temozolomide (CAPTEM) therapy response in patients with neuroendocrine tumors (NET).

PATIENTS AND METHODS

This retrospective study (n = 44) assessed CAPTEM therapy response in neuroendocrine liver metastases (NELM) patients. Among 33 monitored patients, as a subgroup of the overall study cohort, pretherapeutic and follow-up MRI data (size, apparent diffusion coefficient [ADC] values, and signal intensities), along with clinical parameters (chromogranin A [CgA] and Ki-67%), were analyzed. Progression-free survival (PFS) served as the reference. Responders were defined as those with PFS ≥ 6 months.

RESULTS

Most patients were male (75%) and had G2 tumors (76%) with a pancreatic origin (84%). Median PFS was 5.7 months; Overall Survival (OS) was 25 months. Non-responders (NR) had higher Ki-67 in primary tumors (16.5 vs. 10%, p = 0.01) and increased hepatic burden (20% vs. 5%, p = 0.007). NR showed elevated CgA post-treatment, while responders (R) exhibited a mild decrease. ADC changes differed significantly between groups, with NR having decreased ADCmin (-23%) and liver-adjusted ADCmean/ADCmean liver (-16%), compared to R's increases of ADCmin (50%) and ADCmean/ADCmean liver (30%). Receiver operating characteristic (ROC) analysis identified the highest area under the curve (AUC) (0.76) for a single parameter for ∆ ADC mean/liver ADCmean, with a cut-off of < 6.9 (76% sensitivity, 75% specificity). Combining ∆ Size NELM and ∆ ADCmin achieved the best balance (88% sensitivity, 60% specificity) outperforming ∆ Size NELM alone (69% sensitivity, 65% specificity). Kaplan-Meier analysis indicated significantly longer PFS for ∆ ADCmean/ADCmean liver < 6.9 (p = 0.024) and ∆ Size NELM > 0% + ∆ ADCmin < -2.9% (p = 0.021).

CONCLUSIONS

Survival analysis emphasizes the need for adapted response criteria, involving combined evaluation of CgA, ADC values, and tumor size for monitoring CAPTEM response in hepatic metastasized NETs.

Neuroendocrine Tumor Therapy Response Assessment

Peptide receptor radionuclide therapy has become an integral part of management of neuroendocrine neoplasms. Gallium-68- and lutetium-177-labeled somatostatin receptor analogues have replaced yttrium-90- and 111-indium-based tracers. Several newer targeted therapies are also being used in clinical and research settings. It is imperative to accurately evaluate the response to these agents. The characteristics of NENs and the response patterns of the targeted therapies make response assessment in this group challenging. This article provides an overview of the strengths and weaknesses of the various biomarkers available for response assessment.

Resistance to targeted treatment of gastroenteropancreatic neuroendocrine tumors

The mammalian target of rapamycin (mTOR) is part of the phosphoinositide-3-kinase (PI3K)/protein kinase B (Akt)/mTOR signaling. The PI3K/Akt/mTOR pathway has a pivotal role in the oncogenesis of neuroendocrine tumors (NETs). In addition, vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) drive angiogenesis in NETs and therefore contributes to neuroendocrine tumor development. Hence, mTOR and angiogenesis inhibitors have been developed. Everolimus, a first-generation mTOR inhibitor, has shown significant survival benefit in advanced gastroenteropancreatic NETs. Sunitinib, a pan-tyrosine kinase inhibitor that targets the VEGF receptor, has proven to increase progression-free survival in advanced pancreatic NETs. Nevertheless, primary and acquired resistance to rapalogs and sunitinib has limited the clinical benefit for NET patients. Despite the identification of multiple molecular mechanisms of resistance, no predictive biomarker has made it to the clinic. This review is focused on the mTOR signaling and angiogenesis in NET, the molecular mechanisms of primary and acquired resistance to everolimus and sunitinib and how to overcome this resistance by alternative drug compounds.

The pivotal role of mammalian target of rapamycin inhibition in the treatment of patients with neuroendocrine tumors

Significant advances have been made toward understanding the biology of neuroendocrine tumors (NET) in terms of defining prognosis and improving clinical management; however, many unmet needs remain. The treatment landscape for NET has evolved, with the approval of the targeted agents everolimus and sunitinib for the treatment of advanced pancreatic NET in 2011 followed by the approval of everolimus for the treatment of advanced nonfunctional gastrointestinal and lung NET in 2016. Mammalian target of rapamycin (mTOR) and components of the mTOR pathway play pivotal roles in NET pathogenesis. Effects of the mTOR inhibitor everolimus have been well documented in preclinical and clinical studies, both as monotherapy and combination therapy. mTOR inhibition as backbone therapy within the NET treatment landscape is a focus of continuing research, which includes evaluation of the growing armamentarium of approved and investigational agents as potential combination partners. Data evaluating the clinical benefits of agents targeting mTOR and related pathways (alone and in combination) in the treatment of patients with NET continue to increase. Many of the findings to date are encouraging.

Challenges in the Diagnosis and Management of Well-Differentiated Neuroendocrine Tumors of the Lung (Typical and Atypical Carcinoid): Current Status and Future Considerations

Neuroendocrine tumors (NET) of the lung represent approximately 25% of all primary lung tumors and can be classified as low grade (typical carcinoids), intermediate grade (atypical carcinoids), or high grade (large cell neuroendocrine carcinoma or small cell lung carcinoma). Low- and intermediate-grade lung NET are increasingly recognized as biologically distinct from high-grade lung NET based on clinical behavior and underlying molecular abnormalities. This review summarizes current knowledge and challenges in the diagnosis and management of low- and intermediate-grade lung NET. Accurate histopathologic classification of lung NET is critical to determining appropriate treatment options but can be challenging even for experts. For low- and intermediate-grade lung NET, surgery remains the mainstay of treatment for localized disease. Although no standard systemic therapy has been established for the treatment of advanced, unresectable disease, a number of promising treatment options are emerging, including somatostatin analogs, temozolomide-based chemotherapy, targeted therapy with mammalian target of rapamycin or vascular endothelial growth factor inhibitors, and peptide receptor radionuclide therapy. Given the difficulty in accurately diagnosing these tumors, and the paucity of data supporting establishment of standard systemic therapy options, management of patients within the setting of a multidisciplinary team, including specialists with expertise in NET, is recommended. Ongoing and future clinical trials hopefully will provide stronger evidence to support treatment recommendations for low- and intermediate-grade lung NET.

An Overview on the Sequential Treatment of Pancreatic Neuroendocrine Tumors (pNETs)

Patients suffering from pancreatic neuroendocrine tumors (pNETs) are now candidates to receive novel approved drugs that have demonstrated benefit in disease control rate and delay the time taken for tumor progression in Phase III clinical trials; for example, sunitinib, everolimus and lanreotide. Though pNETs represent a rare and heterogeneous disease, recent approaches are being taken to better understand the molecular pathways involved in carcinogenesis. Consequently, new treatment strategies are now available and others still under investigation show promising results. However, some questions around how to approach patients with pNETs are still unresolved, such as what the best sequence of treatments we can offer to each of our patients in the clinic at any time of their disease would be. Therapeutic decisions are, at the moment, guided by clinical judgment, based on different parameters coming from retrospective analysis and non-randomized clinical trials. However, advances in genomic research would lead to a more precise approach using therapeutic targets that would also allow the development of new agents, prognostic or predictive biomarkers and a better understanding of resistance mechanisms. The following article is a comprehensive review of the approved and investigational drugs in pNET, and highlights the current concerns about treatment sequencing, but also provides an update of some of the present and future efforts for an improvement in the therapeutic algorithm of the disease.

Pancreatic neuroendocrine tumors: targeting the molecular basis of disease. Curr Opin Oncol. 2015;27:38-43. [PMID: 25390554 DOI: 10.1097/cco.0000000000000146]

PURPOSE OF REVIEW

Pancreatic neuroendocrine tumors (pNETs) are a rare and heterogeneous group of neoplasia. Presentation of these tumors can vary widely. Current treatment modalities range from potentially curative surgical interventions in localized disease to the use of varied hormonal analogues, cytotoxic agents and targeted therapy for the management of locally advanced and metastatic disease. With such a wide variety of therapeutic modalities, clinicians are faced with the task of building an effective and comprehensive treatment strategy for their patients.

RECENT FINDINGS

Targeted therapy for pNET is limited to sunitinib and everolimus. There have been a number of important studies assessing the efficacy of other targeted agents, in addition to the conjugation of these agents in the management of advanced pNET. This review will stand to highlight currently available targeted therapies for the treatment of advanced pNET.

SUMMARY

The use of targeted agents in the management of advanced pNET has significant potential to change the current standard of care. In addition to the use of long-acting somatostatin analogues, targeting the mammalian target of rapamycin and vascular endothelial growth factor pathways can be well tolerated and may lead to long periods of disease control in a wide variety of neuroendocrine tumors involving the pancreas.

Dual inhibition of mTOR pathway and VEGF signalling in neuroendocrine neoplasms: from bench to bedside

After years of limited progress in the treatment of neuroendocrine neoplasms (NENs), an increasing number of therapeutic targets have recently emerged as potential tools to improve disease outcome. The mammalian target of rapamycin (mTOR) pathway and vascular endothelial growth factor (VEGF) signalling are implicated in the regulation of cell growth, proliferation, neo-angiogenesis and tumour cell spread. Their combined blockade, in a simultaneous or sequential strategy, represents an intriguing biological rationale to overcome the onset of resistance mechanisms. However, is becoming increasingly imperative to find the optimal sequential strategy according to the best toxicity profile, and also to identify predictive biomarkers. We will provide an overview of the pre-clinical and clinical data relating to mTOR pathway/VEGF signalling as a potential targets of treatment in NENs.

A tale of two tumors: treating pancreatic and extrapancreatic neuroendocrine tumors

Despite their perceived rarity, gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are rising in incidence and prevalence. The biology, natural history, and therapeutic options for GEP-NETs are heterogeneous: NETs arising in the pancreas can be distinguished from those arising elsewhere in the gastrointestinal tract, and therapy is dichotomized between these two groups. Somatostatin analogues are the mainstay of oncologic management of bowel NETs; everolimus, streptozocin, and sunitinib are approved to treat pancreatic NETs. There are significant differences in molecular genetics between pancreatic and extrapancreatic NETs, and studies are evaluating whether additional NET patients may benefit from targeted agents. We discuss the distinguishing features of these two groups of tumors, as well as the therapeutic implications of the distinction. We also examine the evolving therapeutic landscape and discuss the likelihood that treatment will be developed independently for pancreatic and extrapancreatic gastrointestinal NETs, with novel therapeutics effective for newly identified pathologically or molecularly defined subgroups.

Targeting the mTOR signaling pathway in neuroendocrine tumors

OPINION STATEMENT

Neuroendocrine tumors (NETs) are a heterogeneous group of malignancies characterized by variable but most often indolent biologic behavior. Well-differentiated NETs can be broadly classified as either carcinoid or pancreatic NET. Although they have similar characteristics on routine histologic evaluation, the 2 tumor subtypes have different biology and respond differently to treatment, with most therapeutic agents demonstrating higher response rates in pancreatic NETs compared with carcinoid. Until recently, systemic treatment options for patients with advanced NETs were limited. However, improvements in our understanding of signaling pathways involved in the pathogenesis, growth, and spread of NETs have translated into an expansion of treatment options. Aberrant signaling through the mechanistic pathway of rapamycin (mTOR) pathway has been implicated in neuroendocrine tumorigenesis. Additionally, altered expression of mTOR pathway components has been observed in NETs and has been associated with clinical outcomes. Targeting the mTOR pathway has emerged as an effective treatment strategy in the management of advanced NETs. In a randomized, placebo-controlled study of patients with advanced pancreatic NET, treatment with the mTOR inhibitor everolimus was associated with improved progression-free survival (PFS). Largely based upon these data, everolimus has been approved in the United States and Europe for the treatment of patients with advanced pancreatic NET. The activity of everolimus remains under investigation in patients with carcinoid tumors. In a randomized study of patients with advanced carcinoid tumors associated with carcinoid syndrome, the addition of everolimus to octreotide was associated with improved PFS compared with octreotide. However, the results did not meet the prespecified level of statistical significance based on central review of radiographic imaging. Results from a randomized study examining the efficacy of everolimus in patients with nonfunctional gastrointestinal and lung NETs are awaited. In addition, further investigation is needed to determine whether primary tumor site or other clinical and molecular factors can impact response to mTOR inhibition. Although everolimus can slow tumor progression, significant tumor reduction is rarely obtained. Targeting multiple signaling pathways is a treatment strategy that may provide better tumor control and overcome resistance mechanisms involved with targeting a single pathway. Results of ongoing and future studies will provide important information regarding the added benefit of combining mTOR inhibitors with other targeted agents, such as VEGF pathway inhibitors, and cytotoxic chemotherapy in the treatment of advanced NETs.

Evaluating digestive neuroendocrine tumor progression and therapeutic responses in the era of targeted therapies: state of the art

Well-differentiated neuroendocrine tumors (NETs) are a group of heterogeneous rare tumors. They are often slow-growing and patients can have very long survival, even at the metastatic stage. The evaluation of tumor progression and therapeutic responses is currently based on Response Evaluation Criteria In Solid Tumors v1.1 (RECIST) criteria. As for other malignancies, RECIST criteria are being reexamined for NETs in the era of targeted therapies because tumor response to targeted therapies is rarely associated with shrinkage, as opposed to prolonged progression-free survival. Therefore, size-based criteria no longer seem to be suitable to the assessment of NET progression and therapeutic responses, especially considering targeted therapies. New imaging criteria, combining morphological and functional techniques, have proven relevant for other malignancies treated with targeted therapies. To date, such studies have rarely been conducted on NETs. Moreover, optimizing the management of NET patients also requires considering clinical, biological, and pathological aspects of tumor evolution. Our objectives herein were to comprehensively review current knowledge on the assessment of tumor progression and early prediction of therapeutic responses and to broaden the outlook on well-differentiated NETs, in the era of targeted therapies.

Systemic therapy for advanced pancreatic neuroendocrine tumors

Neuroendocrine tumors (NETs) occur throughout the body, and share similar histologic characteristics. However, it has become increasingly evident that pancreatic NETs tend to respond differently to therapeutic agents than do other NET subtypes. In most cases, systemic therapy has been more effective in NETs of pancreatic origin than in NETs arising from other locations. Traditional systemic treatment options for pancreatic NETs include somatostatin analogs or cytotoxic chemotherapy. Recently, the biologically targeted agents everolimus and sunitinib were approved for use in patients with metastatic disease. Novel agents, as well as novel drug combinations, are currently under investigation.

Management of pancreatic neuroendocrine tumors

Pancreatic neuroendocrine tumors account for 1% to 2% of pancreatic neoplasms and may occur sporadically or as part of a hereditary syndrome. Patients may present with symptoms related to hormone secretion by functional tumors or to locally advanced or metastatic nonfunctional tumors. Asymptomatic pancreatic neuroendocrine tumors are increasingly detected incidentally during abdominal imaging performed for other reasons. The management of localized pancreatic neuroendocrine tumors is surgical resection. Hepatic metastases are common and their management involves a variety of liver-directed therapies, which should be tailored according to extent of disease, symptoms, presence of extrahepatic metastases, and patient performance status.

Phase I study of sorafenib in combination with everolimus (RAD001) in patients with advanced neuroendocrine tumors

PURPOSE

Sorafenib and everolimus are both active against neuroendocrine tumors (NET). Because of potential synergy between VEGF pathway and mTOR inhibitors, we performed a phase I study to evaluate the safety and feasibility of combining sorafenib and everolimus in patients with advanced NET.

METHODS

Patients were treated with everolimus 10 mg daily in combination with sorafenib (dose level 1: 200 mg twice daily; dose level 2: 200 mg per morning, 400 mg per evening) using standard phase I dose escalation design. Dose-limiting toxicity (DLT) was defined within the first cycle (28 days) of therapy. Treatment was continued until tumor progression, unacceptable toxicity, or withdrawal of consent. Twelve additional patients were treated at the maximum tolerated dose (MTD) level to further characterize safety and a preliminary assessment of activity.

RESULTS

One patient in Cohort 1 experienced DLT (grade 3 skin rash); the cohort was expanded to 6 patients with no further DLTs. All 3 patients in Cohort 2 experienced DLT, consisting of thrombocytopenia, hand-foot skin reaction, and rash/allergic reaction. Sorafenib 200 mg twice daily in combination with everolimus 10 mg daily was established as the MTD. Independently reviewed best objective responses revealed that 62 % of patients had some degree of tumor shrinkage. By RECIST, we observed partial response in 1 patient, stable disease in 13 patients, and progressive disease in 3 patients.

CONCLUSION

Sorafenib 200 mg twice daily with everolimus 10 mg daily represents the MTD of this combination in patients with advanced NET. While the combination is active, toxicity concerns may preclude more widespread use.

Translation of molecular pathways into clinical trials of neuroendocrine tumors

Current treatment options for neuroendocrine tumors (NET) include somatostatin analogs, interferon-α, peptide receptor-targeted therapy and cytotoxic chemotherapy. Most patients undergo sequential therapies since these drugs are active only in subpopulations of patients and for a limited period of time. There is a need for novel drugs that are capable of amelioration of symptomatology (syndromic control) and/or tumor growth control. A number of diverse signaling pathways are involved in the pathogenesis of NET and tumor growth, thus many potential targets are available for drug targeting. Targeted therapies therefore represent an appropriate developmental therapeutic strategy given the multiplicity of potential targets in NET. These include but are not limited to: inhibitory or activating G protein-coupled receptors, receptor tyrosine kinases, ligands, and intracellular targets such as the mammalian target of rapamycin (mTOR). Numerous drugs that utilize single or multiple targets are currently in clinical development. Recently, two target-directed agents, the multiple tyrosine kinase inhibitor sunitinib and the mTOR inhibitor everolimus, have been approved for the treatment of progressive pancreatic NET. This review provides a broad overview of established and potential molecular targets in NET, summarizes data from phase II and III clinical trials with targeted drugs and outlines future therapeutic directions.

A shining light in the darkness for the treatment of pancreatic neuroendocrine tumors

Gastroenteropancreatic neuroendocrine tumors are rare neoplasms; past decades have seen limited research channeled into this area. Recently, 2 placebo-controlled phase III trials using 2 drugs--everolimus and sunitinib--with distinct molecular rationales achieved their principal objective of increasing survival in patients with advanced pancreatic neuroendocrine tumors (PNET). Nonetheless, several questions remain unanswered, notably defining the optimal schedule for integrating these targeted agents with conventional cytotoxics and other treatment options, and identifying appropriate biomarkers for patients with the potential to derive greater benefit. In this article, we analyze the results of the 2 largest studies ever completed in patients with PNETs and discuss the challenges for future drug development in this setting.

SUMMARY

Sunitinib and everolimus will become new treatment options for patients with PNETs and will be integrated into the complex therapeutic management of this disease. In this review, we summarize the evidence-based data of these drugs as well as the molecular-based science in this setting that will lay the groundwork for future studies.

Pancreatic neuroendocrine tumors: a comprehensive review

Pancreatic neuroendocrine tumors (NETs) are a heterogeneous group of tumors. Despite being relatively rare, representing just 1-2% of all pancreatic neoplasms, the incidence of pancreatic NET has increased over the past two decades. Although the primary treatment for localized NET is surgical resection, there is still a lack of effective therapeutic options for patients with advanced unresectable pancreatic NET. Recently, the targeted agents sunitinib malate (SUTENT®, Pfizer Inc, NYC) and everolimus (AFINITOR®, Novartis, Basel, Switzerland)-both with different mechanisms of action-received United States Food and Drug Administration approval for the treatment of progressive, well-differentiated, pancreatic NET in patients with unresectable, locally advanced or metastatic disease. SUTENT® also received approval for this indication by the European Commission in 2010. Our article presents an overview of pancreatic NET, with a focus on their diagnostic work-up, clinical presentation and treatment options. Topics for further investigation of targeted therapy are also discussed.

New strategies for advanced neuroendocrine tumors in the era of targeted therapy

Low- to intermediate-grade neuroendocrine tumor (NET) constitutes a group of indolent malignancies that share the capacity for secreting hormones and neuroamines. Until recently, there were few therapeutic options for oncologic control. The PROMID study showed that octreotide long-acting repeatable formulation can delay tumor growth in midgut NETs. And, recent phase III studies showed both everolimus and sunitinib improved progression-free survival in pancreatic NETs, validating the phosphoinositide 3-kinase/Akt/mTOR pathway and angiogenesis as important targets for further advances. Ongoing and planned pivotal studies targeting these pathways in other NET subtypes may widen their therapeutic application. Development of rational combinations may further improve therapeutic outcome. These successes and our improved understanding of the underlying molecular biology are likely to lead to further important advances on the horizon.

Novel medical therapies of recurrent and metastatic gastroenteropancreatic neuroendocrine tumors

Neuroendocrine tumors (NETs) of the gastrointestinal tract and pancreas are slow-growing but commonly advanced malignancies with increasing incidence and prevalence. While locoregional disease can be effectively managed with resection, treatment of recurrent, progressive or metastatic disease has until recently been limited to palliative embolization and cytoreducitve surgery, with cytotoxic chemotherapeutic agents being the last resort. However, novel molecular targeted therapies inhibiting malignant cell proliferation and neoangiogenesis, as well as new cytotoxic chemotherapy drugs and somatostatin analogues, are all being investigated for their potential use in advanced neuroendocrine tumors. Long-acting release forms of octreotide have been shown to not only improve symptoms in carcinoid syndrome but to also delay progression of gastrointestinal NETs. On the other hand, phase III trials have demonstrated everolimus (with octreotide) and sunitinib to increase progression-free survival in pancreatic NETs. Use of bevacizumab has also shown promise in a phase II study, and results of an ongoing phase III trial comparing it to interferon are eagerly expected. Use of radiolabeled somatostatin analogues is still under investigation, though several phase II studies are encouraging. New cytotoxic agents, most notably temozolomide and capecitabine, are already in use, but their relative effectiveness compared to streptozocin in pancreatic NETs is yet to be determined.

Role of biological targeted therapies in gastroenteropancreatic neuroendocrine tumours

Approximately two-thirds of neuroendocrine tumours (NET) occur in the gastrointestinal tract and over 60% present with metastases. With greater insight into molecular pathways involved in tumour progression, opportunities are presented for the use of targeted therapies in NET. Although a wide array of targeted agents has been investigated, only a handful has emerged as forerunners from recent clinical trials. This literature review focuses on the use of anti-angiogenic monoclonal antibody bevacizumab, as well as small molecule inhibitors sunitinib and everolimus.

Emerging therapies for advanced gastroenteropancreatic neuroendocrine tumors

Neuroendocrine tumors comprise a heterogeneous group of neoplasms derived from peptide- and amine-producing cells of the neuroendocrine system. Gastroenteropancreatic NET are differentiated into tumors and carcinomas based on their malignant potential and subdivided into those arising from the pancreas (islet cell tumors or pancreatic NET) and the more classical gut "carcinoids". Moderate to well differentiated NET have historically been considered rare tumors but recent epidemiological statistics suggest that their frequency has increased substantially over the past three decades. While the incidence of NET is increasing, data from both the US and UK demonstrate no improvement in outcomes over a similar time period. Due to the generally indolent biology of NET, most patients present with advanced disease before symptoms become apparent. In patients with localized NET, the 5-year survival rates after resection range from 60 to 90%, while regional lymph node involvement decreases the 5-year survival rates after surgery to 50-75%. Patients with distant metastases have a 5 year survival rate of approximately 25-40%. Conventional cytotoxic chemotherapy is of unclear benefit in patients with these generally slow growing tumors. Multiple agents have been tested in Phase 2 and Phase 3 trials. In general, the lack of major objective responses with significant toxicities has limited routine use of traditional chemotherapy agents and has emphasized the need to develop new agents in these diseases. This review will focus on emerging molecularly-targeted treatments with an emphasis on their underlying biologic and preclinical rationale.

A phase II trial of bevacizumab plus everolimus for patients with refractory metastatic colorectal cancer

PURPOSE

For patients with metastatic colorectal cancer (mCRC), no standard therapy exists after progression on 5-fluorouracil, oxaliplatin, irinotecan, bevacizumab, and cetuximab or panitumumab. Preclinical data demonstrated that combined vascular endothelial growth factor and mammalian target of rapamycin inhibition has greater antiangiogenic and antitumor activity than either monotherapy. A phase I study of bevacizumab plus everolimus demonstrated that the combination is safe; activity was seen in several patients with refractory mCRC.

METHODS

Fifty patients with refractory mCRC were enrolled and received bevacizumab at 10 mg/kg every 2 weeks and everolimus at 10 mg orally daily.

RESULTS

Of the 50 patients enrolled, the median age was 56 years and the median number of prior regimens was four. Forty-seven patients (96%) had prior bevacizumab exposure and 42 patients (84%) had documented progression on prior bevacizumab-based therapy. Forty-nine patients were evaluable for response; eight patients had minor responses (16%) and an additional 15 patients (30%) had stable disease (SD). No complete or partial responses were seen. The median progression-free survival interval was 2.3 months; however, 26% of patients achieved prolonged SD for ≥6 months, and three patients (6%) were on study for >1 year. The median overall survival duration was 8.1 months. The most common grade 1-2 toxicities were mucositis (68%) and hyperlipidemia (64%). Clinically significant grade ≥3 toxicities included hypertension (14%), fistula/abscess/perforation (8%), mucositis (6%), and hemorrhage (2%).

CONCLUSIONS

Bevacizumab plus everolimus is generally tolerable but may have risks related to mucosal damage and/or wound healing. Bevacizumab plus everolimus appears to have modest activity in refractory mCRC in patients.

Future directions in the treatment of neuroendocrine tumors: consensus report of the National Cancer Institute Neuroendocrine Tumor clinical trials planning meeting

Neuroendocrine tumors (NETs) arise from a variety of anatomic sites and share the capacity for production of hormones and vasoactive peptides. Because of their perceived rarity, NETs have not historically been a focus of rigorous clinical research. However, the diagnosed incidence of NETs has been increasing, and the estimated prevalence in the United States exceeds 100,000 individuals. The recent completion of several phase III studies, including those evaluating octreotide, sunitinib, and everolimus, has demonstrated that rigorous evaluation of novel agents in this disease is both feasible and can lead to practice-changing outcomes. The NET Task Force of the National Cancer Institute GI Steering Committee convened a clinical trials planning meeting to identify key unmet needs, develop appropriate study end points, standardize clinical trial inclusion criteria, and formulate priorities for future NET studies for the US cooperative group program. Emphasis was placed on the development of well-designed clinical trials with clearly defined efficacy criteria. Key recommendations include the evaluation of pancreatic NET separately from NETs of other sites and the exclusion of patients with poorly differentiated histologies from trials focused on low-grade histologies. Studies evaluating novel agents for the control of hormonal syndromes should avoid somatostatin analog washout periods when possible and should include quality-of-life end points. Because of the observed long survival after progression of many patients, progression-free survival is recommended as a feasible and relevant primary end point for both phase III studies and phase II studies where a delay in progression is expected in the absence of radiologic responses.

Advances in the therapy of gastroenteropancreatic-neuroendocrine tumours (GEP-NETs)

Neuroendocrine tumours (NET) of the digestive tract comprise a broad range of malignancies. The therapeutic approach to these tumours has not evolved as it did in other tumour types in the last two decades. The deeper knowledge of the underlying molecular biology behind the growth of neuroendocrine cells has brought much information to light. We now know that somatostatin analogues may not only be considered as symptomatic treatment but also as antitumour agents. Sunitinib, a tyrosine kinase (TK) inhibitor with antiangiogenic and antitumoural properties, has been shown to induce significant improvement in progression-free survival in a randomised trial conducted in well-differentiated pancreatic islet-cell NETs. The relevance of the phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/Akt/mTOR) pathway seems to be crucial in gastroenteropancreatic (GEP)-NETs. In fact, mTOR inhibitors have shown activity in uncontrolled trials, and large, randomised trial results will be available shortly. In this article, we summarise the most recent available data on medical therapy for GEPNETs.