Targeted therapies in neuroendocrine tumors (NET): clinical trial challenges and lessons learned

In the past 3 years, we have witnessed the completion of four randomized phase III studies in neuroendocrine tumors and the approval of two new drugs, everolimus and sunitinib, for the treatment of patients with well-differentiated pancreatic neuroendocrine tumors. These studies demonstrate a shift from case series and single-arm studies toward prospective, randomized controlled clinical trials and evidence-based therapy in the neuroendocrine tumor field. However, the clinical development of these agents also highlights the potential challenges awaiting other new drugs in this area. Herein, we discuss the strengths and weaknesses of the most recent phase II and phase III neuroendocrine tumor studies and discuss how limitations inherent in current trial design can lead to potential pitfalls. We also discuss how trial design can be improved, with the hope of increasing the number of drugs successfully developed to treat patients with neuroendocrine tumors.

Evaluation of the WHO 2010 grading and AJCC/UICC staging systems in prognostic behavior of intestinal neuroendocrine tumors

Background

The increasing incidence and heterogeneous behavior of intestinal neuroendocrine tumors (iNETs) pose a clinicopathological challenge. Our goal was to decribe the prognostic value of the new WHO 2010 grading and the AJCC/UICC TNM staging systems for iNETs. Moreover, outcomes of patients treated with somatostatin analogs were assessed.

Methods

We collected epidemiological and clinicopathological data from 93 patients with histologically proven iNETs including progression and survival outcomes. The WHO 2010 grading and the AJCC/UICC TNM staging systems were applied for all cases. RECIST criteria were used to define progression. Kaplan-Meier analyses for progression free survival (PFS) and overall survival (OS) were performed.

Results

Mean follow-up was 58.6 months (4–213 months). WHO 2010 grading yielded PFS and disease-specific OS of 125.0 and 165.8 months for grade 1 (G1), 100.0 and 144.2 months for G2 and 15.0 and 15.8 months for G3 tumors (p = 0.004 and p = 0.001). Using AJCC staging, patients with stage I and II tumors had no progression and no deaths. Stage III and IV patients demonstrated PFS of 138.4 and 84.7 months (p = 0.003) and disease-specific OS of 210.0 and 112.8 months (p = 0.017). AJCC staging also provided informative PFS (91.2 vs. 50.0 months, p = 0.004) and OS (112.3 vs. 80.0 months, p = 0.005) measures with somatostatin analog use in stage IV patients.

Conclusion

Our findings underscore the complementarity of WHO 2010 and AJCC classifications in providing better estimates of iNETS disease outcomes and extend the evidence for somatostatin analog benefit in patients with metastatic disease.

Update on the role of somatostatin analogs for the treatment of patients with gastroenteropancreatic neuroendocrine tumors

Somatostatin analogs (SA) are the standard of care for controlling symptoms of patients with functional gastro-entero-pancreatic neuroendocrine tumors (GEP-NETs). SA control symptoms in more than 70% of patients with carcinoid syndrome. Similar results are obtained in patients with functional, hormone-secreting, pancreatic NETs. The use of SA as antiproliferative agents has been established only recently. Retrospective studies have shown stabilization of tumor growth in >50% of patients with progressive disease. The results of a recent randomized phase III trial (PROMID) demonstrated that the median time to progression in patients with midgut carcinoid tumors treated with octreotide LAR (Long-Acting-Repeatable, Novartis, Basel, Switzerland) was more than twice as long compared to that of patients treated with placebo. The results of a phase III study of lanreotide versus placebo in nonfunctional NETs are not yet available. More studies are needed to determine whether combining SA with novel targeted treatments will result in enhanced antiproliferative activity compared to treatment with a SA alone. Studies are ongoing using pan-receptor agonists (eg, pasireotide) and chimeric dimers, which possess features of somatostatin and dopamine agonists (dopastatins) and are thought to enhance symptom control by binding multiple receptors (somatostatin and dopamine receptors). Somatostatin receptor antagonists are also currently being developed for clinical use. Peptide receptor radionuclide therapy (PRRT), consisting of yttrium-90 and lutetium-177 isotopes conjugated with SA appear to be efficacious in advanced NETs. Randomized studies are needed to definitively establish the safety and efficacy of this strategy compared to other available treatments, and to determine which radiolabeled isotopes or combinations are most effective.

Systemic therapeutic options for carcinoid

"Carcinoids" are mostly slow-growing neuroendocrine neoplasms (NENs) with low proliferative activity. A wide range of therapeutic options with variable efficacy exist, including locoregional ablative strategies. Thereafter, some patients may not require medical therapy for years depending on the rate of progression or recurrence. However, the majority of patients require systemic treatment and therein lies the dilemma, since no antiproliferative agent is currently approved for carcinoids. Somatostatin analogs (SSAs), and to a lesser extent interferon-alpha, are standard therapy for carcinoids associated with the carcinoid syndrome. These drugs have some antiproliferative efficacy. SSAs rarely lead to tumor remission but may modestly prolong time to tumor progression. Chemotherapy is of limited value in carcinoids with low proliferation indices but may be useful in higher grade tumors. Peptide receptor-targeted radionuclide therapy may be of benefit and is mostly used after medical therapies fail. However, it is considered an investigational modality. More recently, targeted drugs such as mammalian target of rapamycin (mTOR) inhibitors and anti-angiogenics have been investigated. Objective remissions are rare. Their value remains to be rigorously elucidated. Increased efficacy requires a better understanding of the underlying tumor biology and identification of molecular pathological criteria to allow appropriate preselection of candidates for targeted therapies.

Angiogenic inhibitors for older patients with advanced colorectal cancer: Does the age hold the stage?

Although major progress has been achieved in the treatment of advanced colorectal cancer (CRC) with the employment of antiangiogenic agents, several questions remain on the use of these drugs in older patients. Since cardiovascular, renal and other comorbidities are common in the elderly, an accurate assessment of the patients’ conditions should be performed before a treatment decision is made. Since most CRC patients enrolled in clinical trials testing antiangiogenic drugs were aged < 65 years, the efficacy and tolerability of these agents in elderly patients has not been adequately explored. Data suggest that patients with advanced CRC derive similar benefit from bevacizumab treatment regardless of age, but the advantage of other antiangiogenic drugs in the same class of patients appears more blurred. Literature data suggest that specific antiangiogenic-related toxicities such as hypertension or arterial thromboembolic events may be higher in the elderly than in the younger patients. In addition, it should be emphasized that the patients included in the clinical studies discussed herein were selected and therefore may not be representative of the usual elderly population. Advanced age alone should not discourage the use of bevacizumab. However, a careful patients’ selection and watchful monitoring of toxicities are required to optimize the use of antiangiogenics in this population.

Critical appraisal of the use of regorafenib in the management of colorectal cancer

The lack of valid clinical management options for patients affected by metastatic colorectal cancer, which has progressed after all approved standard treatments, has lead to research into new active molecules. Regorafenib is an oral small-molecule multi kinase inhibitor, binding to several intracellular kinases, with powerful inhibitory activity against vascular endothelial growth factor receptors (VEGFR-1,VEGFR-2, and VEGFR-3), platelet-derived growth factor receptor, fibroblast growth factor receptor 1, Raf, TIE-2, and the kinases KIT, RET, and BRAF. The antitumor activity of regorafenib has been tested in vitro and in vivo, and inhibition of tumor growth has been observed in several cancer models, particularly colorectal cancer and gastrointestinal stromal tumors. The most frequent adverse events of grade 3 or higher related to regorafenib were hand-foot skin reaction, fatigue, diarrhea, hypertension, and rash or desquamation. Only a few Phase I–II trials, and most recently a Phase III trial in pretreated colorectal cancer, have been carried out to date. Several ongoing trials are testing the efficacy of regorafenib in combination with chemotherapy. At this point in time, regorafenib is the first small-molecule tyrosine kinase inhibitor to gain approval by the US Food and Drug Administration for pretreated metastatic colorectal cancer patients.

A phase I study of the combination of temsirolimus with irinotecan for metastatic sarcoma

mTOR inhibitors are emerging as important anti-neoplastic agents with a wide range of clinical applications. The topoisomerase I inhibitor irinotecan is a potent DNA damaging drug, with a broad spectrum of anticancer activities. mTOR appears to enhance cancer cell survival following DNA damage, thus the inhibition of mTOR after irinotecan could theoretically show synergistic activities in patients. Both mTOR inhibitors and irinotecan have been used as single agents in soft tissue sarcomas with limited efficacy. We completed a phase I trial of the combination of the mTOR inhibitor, temsirolimus, and irinotecan in patients with advanced soft tissue sarcoma. Seventeen patients were recruited. The Phase II recommended dose is 20 mg of temsirolimus and 80 mg/m² of irinotecan administered on weekly basis for three out of four weeks. Most frequently encountered toxicities include cytopenias, fatigue, and gastrointestinal toxicities. Two patients (one with leiomyosarcoma and one with high grade undifferentiated sarcoma) had stable disease for more than 12 months.

Regorafenib: carving a niche in the crowded therapeutic landscape

The oral multikinase inhibitor regorafenib targets both tumor cell proliferation and vasculature and is active in heavily pretreated patients with metastatic colorectal cancer, for which the US FDA granted its approval in September 2012. The benefit for regorafenib was seen in these patients in most prespecified subgroups. The drug is also being used in other tumor types where it has shown exciting potential especially in gastrointestinal stromal tumors. The drug is well tolerated but requires close monitoring during administration. Common side effects include asthenia/tiredness, loss of appetite, hand-foot skin syndrome, diarrhea, mucositis, weight loss, infections, hypertension and rash. Serious adverse events to look out for are liver toxicity, hemorrhage and gastrointestinal perforation. Biomarker data should help us to optimize the use of these drugs to select which patients are most likely to benefit.

Long-term management of a patient with well-differentiated pulmonary neuroendocrine carcinoma: a case report

Pulmonary neuroendocrine tumors (NET) are rare, and very few published reports have described the long-term treatment of patients with this disease. Current treatment options for patients with metastatic well-differentiated pulmonary NET are limited. This case report details the long-term treatment of a 62-year-old female patient with well-differentiated pulmonary NET and multiple liver metastases. The heavily pretreated patient achieved radiographic stability in measurable disease, improvement in nonmeasurable disease, and symptomatic improvement over 3 years while receiving the combination of everolimus and octreotide long-acting repeatable (LAR). Treatment was well tolerated without mucositis, rash, or pneumonitis. This case report suggests that the combination of everolimus and octreotide LAR may be a novel treatment option for heavily pretreated patients with metastatic well-differentiated pulmonary NET, but these findings require further analysis in clinical trials.

Practical management of everolimus-related toxicities in patients with advanced solid tumors

Everolimus is an orally administered inhibitor of the mammalian target of rapamycin (mTOR), an intracellular protein kinase downstream of the phosphatidylinositol 3-kinase/AKT pathway involved in key components of tumorigenesis, including cell growth, proliferation, and angiogenesis. In the advanced cancer setting, based on favorable results from phase III trials, everolimus is indicated for the treatment of advanced renal cell carcinoma, advanced neuroendocrine tumors of pancreatic origin, and advanced hormone receptor-positive, human epidermal growth factor receptor 2-negative breast cancer. Additional oncology indications for everolimus include renal angiomyolipoma with tuberous sclerosis complex and subependymal giant-cell astrocytoma. Although it is generally well tolerated, with most adverse events of mild to moderate severity and manageable, everolimus exhibits a distinct adverse event profile that warrants guidance for proper diagnostic and medical management. This guidance is particularly important given the potential for widespread long-term use of everolimus. This review will focus on the most relevant toxicities associated with mTOR inhibitors and on their management. Practical treatment recommendations are presented for stomatitis, noninfectious pneumonitis, rash, selected metabolic abnormalities, and infections. Provided these events are rapidly identified and treated, the vast majority should resolve with minimal effect on treatment outcomes and patients' quality of life.

Everolimus plus octreotide long-acting repeatable in patients with advanced lung neuroendocrine tumors: analysis of the phase 3, randomized, placebo-controlled RADIANT-2 study

BACKGROUND

The incidence of neuroendocrine tumors (NETs) has increased approximately fivefold since the 1980s. A similar increase in the incidence of lung NETs has been reported, but therapy has not been optimized.

METHODS

This exploratory subanalysis evaluated the efficacy and safety of everolimus plus octreotide long-acting repeatable (LAR) in a cohort of patients with low- to intermediate-grade advanced lung NET from the phase 3, randomized, placebo-controlled RADIANT-2 (RAD001 in Advanced Neuroendocrine Tumors) study. The primary end point was progression-free survival (PFS). Secondary end points included objective response rate, overall survival, change from baseline in biomarker levels, and safety outcomes.

RESULTS

Patients were randomly assigned to everolimus plus octreotide LAR (n 5 33) or placebo plus octreotide LAR (n 5 11). Median PFS was 13.63 months in the everolimus plus octreotide LAR arm compared with 5.59 months in the placebo plus octreotide LAR arm (relative risk for progression: HR, 0.72; 95% CI, 0.31–1.68; P 5 .228). More patients receiving everolimus plus octreotide LAR (67%) experienced minor tumor shrinkage (not partial response as per RECIST [Response Evaluation Criteria in Solid Tumors]) than those receiving placebo plus octreotide LAR (27%). Most frequently reported adverse events (AEs) included stomatitis, rash, diarrhea, and asthenia. This was consistent with the overall RADIANT-2 trial and the safety profile of everolimus.

CONCLUSIONS

This exploratory subgroup analysis of the RADIANT-2 trial indicates that in patients with advanced lung NET, the addition of everolimus to octreotide LAR improves median PFS by 2.4-fold compared with placebo plus octreotide LAR. These clinically significant observations support the continued evaluation of everolimus treatment regimens in this patient population.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT00412061

Survival of infiltrative hepatocellular carcinoma patients with preserved hepatic function after treatment with transarterial chemoembolization

PURPOSE

Transarterial chemoembolization (TACE) is highly effective and safe therapeutic modality for unresectable hepatocellular carcinoma (HCC). However, the role of TACE for infiltrative HCC has never been elucidated owing to the concern about hepatic failure and subsequent mortality after the procedure. In this study, we aimed to document whether patients with infiltrative HCC would benefit from TACE.

METHODS

Child-Pugh class A/B patients who were newly diagnosed as infiltrative HCC and treated with curative-intent TACE were enrolled. All radiological images were reviewed by a radiologist with more than 20 years of experience in TACE.

RESULTS

Among 1,184 patients newly diagnosed as HCC, 233 (19.7 %) had infiltrative-type tumors and 128 (54.9 %) underwent curative-intent TACE. Although the median overall survival was 5.4 months (IQR 3.1-13.9 months) and 16 (12.5 %) patients had experienced significant complications, 19 (15.9 %) patients survived more than 2 years after the first diagnosis. In multivariable analysis, age >60 years old (HR 0.54, 95 % CI 0.31-0.92), Child-Pugh class A (HR 0.48, 95 % CI 0.30-0.76), and a major PVT without parasitic supply (HR 0.66, 95 % CI 0.44-0.99) were independent favorable prognostic factors. Development of significant complication after TACE was a significant hazard factor of survival (HR 1.99, 95 % CI 1.09-3.62).

CONCLUSIONS

In carefully selected patients with preserved hepatic function and good performance, TACE may achieve long-term survival of infiltrative HCC patients with major PVT without parasitic supply. However, the risk of morbidity and immediate mortality after TACE should be considered to select subjects for the procedure.

Systemic treatment in unresectable metastatic well-differentiated carcinoid tumors: consensus results from a modified delphi process

OBJECTIVES

This study aimed to develop expert consensus for the use of systemic treatments for unresectable metastatic well-differentiated (grade 1-2) carcinoid tumors using the RAND/UCLA modified Delphi process.

METHODS

After a comprehensive literature review, 404 patient scenarios addressing the use of systemic treatments for carcinoid tumors were constructed. A multidisciplinary panel of 10 physicians assessed the scenarios as appropriate, inappropriate, or uncertain (on a 1-9 scale) or as an area of disagreement before and after an extended discussion of the evidence.

RESULTS

Experts were medical and surgical oncologists, interventional radiologists, and gastroenterologists. Among rated scenarios, disagreement decreased from 14% before the meeting to 4% after. Consensus statements about midgut carcinoids included the following: (1) Somatostatin analogs are appropriate as first-line therapy for all patients; (2) In patients with uncontrolled secretory symptoms, it is appropriate to increase the dose/frequency of octreotide long-acting repeatable up to 60 mg every 4 weeks or up to 40 mg every 3 weeks as second-line therapy for refractory carcinoid syndrome. Other options may also be appropriate. Consensus was similar for non-midgut carcinoids.

CONCLUSIONS

The Delphi process provided a structured methodological approach to assist clinician experts in reaching consensus on the appropriateness of specific medical therapies for the treatment of advanced carcinoid tumors.

Sorafenib in combination with oxaliplatin, leucovorin, and fluorouracil (modified FOLFOX6) as first-line treatment of metastatic colorectal cancer: the RESPECT trial

PURPOSE

This randomized, double-blind, placebo-controlled, phase IIb study evaluated adding sorafenib to first-line modified FOLFOX6 (mFOLFOX6) for metastatic colorectal cancer (mCRC).

EXPERIMENTAL DESIGN

Patients were randomized to sorafenib (400 mg b.i.d.) or placebo, combined with mFOLFOX6 (oxaliplatin 85 mg/m(2); levo-leucovorin 200 mg/m(2); fluorouracil 400 mg/m(2) bolus and 2400 mg/m(2) continuous infusion) every 14 days. Primary endpoint was progression-free survival (PFS). Target sample was 120 events in 180 patients for >85% power (two-sided α = 0.20) to detect an HR = 0.65.

RESULTS

Of 198 patients randomized, median PFS for sorafenib plus mFOLFOX6 was 9.1 months versus 8.7 months for placebo plus mFOLFOX6 (HR = 0.88; 95% CI, 0.64-1.23; P = 0.46). There was no difference between treatment arms for overall survival. Subgroup analyses of PFS and overall survival showed no difference between treatment arms by KRAS or BRAF status (mutant and wild type). The most common grade 3/4 adverse events in the sorafenib and placebo arms were neutropenia (48% vs. 22%), peripheral neuropathy (16% vs. 21%), and grade 3 hand-foot skin reaction (20% vs. 0%). Treatment discontinuation because of adverse events was 9% and 6%, respectively. Generally, dose intensity (duration and cumulative doses) was lower in the sorafenib arm than in the placebo arm.

CONCLUSION

This study did not detect a PFS benefit with the addition of sorafenib to first-line mFOLFOX6 for mCRC. KRAS and BRAF status did not seem to impact treatment outcomes but the subgroups were small. These results do not support further development of sorafenib in combination with mFOLFOX6 in molecularly unselected patients with mCRC.

Regorafenib in combination with FOLFOX or FOLFIRI as first- or second-line treatment of colorectal cancer: results of a multicenter, phase Ib study

Background

Metastatic colorectal cancer (mCRC) is commonly treated with 5-fluorouracil, folinic acid, and oxaliplatin or irinotecan. The multitargeted kinase inhibitor, regorafenib, was combined with chemotherapy as first- or second-line treatment of mCRC to assess safety and pharmacokinetics (primary objectives) and tumor response (secondary objective).

Patients and methods

Forty-five patients were treated every 2 weeks with 5-fluorouracil 400 mg/m² bolus then 2400 mg/m² over 46 h, folinic acid 400 mg/m², and either oxaliplatin 85 mg/m² or irinotecan 180 mg/m². On days 4–10, patients received regorafenib 160 mg orally once daily.

Results

The median duration of treatment was 108 (range 2–345 days). Treatment was stopped for adverse events or death (17 patients), disease progression (11 patients), and consent withdrawal or investigator decision (11 patients). Six patients remained on regorafenib at data cutoff (two without chemotherapy). Drug-related adverse events occurred in 44 patients [grade ≥3 in 32 patients: mostly neutropenia (17 patients) and leukopenia, hand–foot skin reaction, and hypophosphatemia (four patients each)]. Thirty-three patients achieved disease control (partial response or stable disease) for a median of 126 (range 42–281 days).

Conclusion

Regorafenib had acceptable tolerability in combination with chemotherapy, with increased exposure of irinotecan and SN-38 but no significant effect on 5-fluorouracil or oxaliplatin pharmacokinetics.

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.

Angiopoietin-2: an attractive target for improved antiangiogenic tumor therapy

Anti-VEGF pathway therapies primarily target immature blood vessels in tumors. However, emerging approaches to combine with targeted therapies impacting the later stages of remodeling and vessel maturation are expected to improve clinical efficacy by expanding the target vessel population. The angiopoietin/Tie ligand/receptor system is a prototypic regulator of vessel remodeling and maturation. Angiopoietin-2 (Ang2) appears to be a particularly attractive therapeutic target. In fact, the experimental proof-of-concept showing improved efficacy when VEGF and Ang2-targeting therapies are combined has been solidly established in preclinical models, and several Ang2-targeting drugs are in clinical trials. However, rational development of these second-generation combination therapies is hampered by a limited understanding of the biological complexity that is generated from agonistic and antagonistic Ang/Tie signaling. This review discusses recent mechanistic advances in angiopoietin signaling, particularly in light of the recent study published on REGN910 and summarizes the status quo of Ang2-targeting therapies. In light of the clarified partial agonist function of Ang2, we propose that clarity on the expression profile of the angiopoietin ligands and Tie1 and Tie2 receptors in subsets of cancer vessels and cancer cells will provide clearer hypotheses for more focused rational clinical trials to exploit this seminal pathway and improve current antiangiogenic therapies.

Current and Novel Treatment Options for Metastatic Colorectal Cancer: Emphasis on Aflibercept

Worldwide, colorectal cancer (CRC) is the third most frequently diagnosed cancer in men and the second in women. Metastatic disease develops in more than half of the patients and carries a poor prognosis. Over the past three decades, significant advances have been made in the treatment of metastatic colorectal cancer (mCRC). The development of new cytotoxic agents and the incorporation of target-specific agents in first-, second-, third-, and nowadays even fourth-line treatment has prolonged median overall survival up to 24–28 months. However, 5-year survival rates remain disappointingly low. This review summarizes the currently available cytotoxic treatment options for mCRC, and highlights the further emerging role of vascular endothelial growth factor (VEGF)-inhibiting strategies, emphasizing the role of aflibercept. Aflibercept is a recombinant fusion protein with high VEGF affinity, and is the second antiangiogenic agent to obtain registration in the treatment of mCRC.

Promoter CpG island hypermethylation of the DNA repair enzyme MGMT predicts clinical response to dacarbazine in a phase II study for metastatic colorectal cancer

PURPOSE

O(6)-methylguanine-DNA-methyltransferase (MGMT) is a DNA repair protein removing mutagenic and cytotoxic adducts from O(6)-guanine in DNA. Approximately 40% of colorectal cancers (CRC) display MGMT deficiency due to the promoter hypermethylation leading to silencing of the gene. Alkylating agents, such as dacarbazine, exert their antitumor activity by DNA methylation at the O(6)-guanine site, inducing base pair mismatch; therefore, activity of dacarbazine could be enhanced in CRCs lacking MGMT. We conducted a phase II study with dacarbazine in CRCs who had failed standard therapies (oxaliplatin, irinotecan, fluoropyrimidines, and cetuximab or panitumumab if KRAS wild-type).

EXPERIMENTAL DESIGN

All patients had tumor tissue assessed for MGMT as promoter hypermethylation in double-blind for treatment outcome. Patients received dacarbazine 250 mg/m(2) intravenously every day for four consecutive days, every 21 days, until progressive disease or intolerable toxicity. We used a Simon two-stage design to determine whether the overall response rate would be 10% or more. Secondary endpoints included association of response, progression-free survival, and disease control rate with MGMT status.

RESULTS

Sixty-eight patients were enrolled from May 2011 to March 2012. Patients received a median of three cycles of dacarbazine (range 1-12). Grades 3 and 4 toxicities included: fatigue (41%), nausea/vomiting (29%), constipation (25%), platelet count decrease (19%), and anemia (18%). Overall, two patients (3%) achieved partial response and eight patients (12%) had stable disease. Disease control rate (partial response + stable disease) was significantly associated with MGMT promoter hypermethylation in the corresponding tumors.

CONCLUSION

Objective clinical responses to dacarbazine in patients with metastatic CRC are confined to those tumors harboring epigenetic inactivation of the DNA repair enzyme MGMT.

PI3K/Akt/mTOR pathway inhibitors in the therapy of pancreatic neuroendocrine tumors

The phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway is implicated in the pathogenesis of pancreatic neuroendocrine tumors (pNETs). Activation of this pathway is driven by aberrant tyrosine kinase receptor activities. Mutations in the PI3K/Akt/mTOR pathway occur in 15% of pNETs, and expression of genes of the PI3K/Akt/mTOR pathway is altered in the majority of pNETs. The mTOR inhibitor everolimus has been approved by the FDA for the treatment of pNET, but its efficacy may be limited by its inability to prevent mTORC2-mediated activation of Akt. Specific inhibitors of PI3K, Akt, or other pathway nodes, and their concomitant use with mTOR inhibitors, or agents with dual activity, may be more effective. Preclinical studies demonstrate that inhibitors of the PI3K pathway have antitumor activity in pNET cells, either through direct inhibition of individual pathway nodes or indirect inhibition of molecular chaperones such as heat-shock protein 90. Clinical studies are underway evaluating individual node and dual node inhibitors.

Second-line cetuximab/irinotecan versus oxaliplatin/fluoropyrimidines for metastatic colorectal cancer with wild-type KRAS

The goal of the present study was to compare the efficacy of the combination of cetuximab and irinotecan to the combination of oxaliplatin and fluoropyrimidines as second-line chemotherapy in patients with irinotecan-refractory and oxaliplatin-naïve metastatic colorectal cancer (mCRC) harboring wild-type KRAS. The study included 120 patients with mCRC who had progressed after irinotecan-containing first-line chemotherapy and were never treated with oxaliplatin; 40 patients with wild-type KRAS were accrued prospectively in the experimental arm (arm A), and 80 patients accrued retrospectively were divided into control arms B (n = 46) and C (n = 34) according to KRAS genotype. Second-line treatments consisted of cetuximab plus irinotecan for arm A, and oxaliplatin plus either 5-fluorouracil (FOLFOX) or capecitabine (CapeOX) for the control arms. The median progression-free survival (PFS) was 8.3, 5.8 and 3.9 months, for arms A, B and C, respectively, with statistical significance favoring arm A (P = 0.007). Differences in overall survival did not reach statistical significance (18.3 vs 12.6 vs 12.9, P = 0.138), although there was a trend toward longer overall survival in arm A. In terms of benefit from oxaliplatin-containing regimens either as second-line or third-line therapy, the median PFS was 5.0 months in arms B and C as second-line therapy, and 4.0 months in arm A as third-line therapy, with no statistical significance (P = 0.385). Second-line cetuximab plus irinotecan is a valid treatment strategy for mCRC patients with irinotecan-refractory and oxaliplatin-naïve tumors harboring wild-type KRAS. Oxaliplatin-containing chemotherapy resulted in equivalent PFS both as a second-line and a third-line therapy, enabling delay of the administration of FOLFOX and CapeOX until subsequent treatment cycles.

Olfactory receptor 51E1 protein as a potential novel tissue biomarker for small intestine neuroendocrine carcinomas

OBJECTIVE

Late diagnosis hinders proper management of small intestine neuroendocrine carcinoma (SI-NEC) patients. The olfactory receptor, family 51, subfamily E, member 1 (OR51E1) has been reported as a potential novel SI-NEC marker, without protein expression recognition. Thus, we further studied whether the encoded protein may be a novel SI-NEC clinical biomarker.

DESIGN

OR51E1 coding sequence was cloned using total RNA from SI-NEC patient specimens. Quantitative real-time PCR analysis explored OR51E1 expression in laser capture microdissected SI-NEC cells and adjacent microenvironment cells. Moreover, immunohistochemistry investigated OR51E1 protein expression on operation and biopsy material from primary SI-NECs, mesentery, and liver metastases from 70 patients. Furthermore, double immunofluorescence studies explored the potential co-localization of the vesicular monoamine transporter 1 (SLC18A1, generally referred to as VMAT1) and OR51E1 in the neoplastic cells and in the intestinal mucosa adjacent to the tumor.

RESULTS

OR51E1 coding sequence analysis showed absence of mutation in SI-NEC patients at different stages of disease. OR51E1 expression was higher in microdissected SI-NEC cells than in the adjacent microenvironment cells. Furthermore, both membranous and cytoplasmic OR51E1 immunostaining patterns were detected in both primary SI-NECs and metastases. Briefly, 18/43 primary tumors, 7/28 mesentery metastases, and 6/18 liver metastases were 'positive' for OR51E1 in more than 50% of the tumor cells. In addition, co-localization studies showed that OR51E1 was expressed in >50% of the VMAT1 immunoreactive tumor cells and of the enterochromaffin cells in the intestinal mucosa adjacent to the tumor.

CONCLUSION

OR51E1 protein is a potential novel clinical tissue biomarker for SI-NECs. Moreover, we suggest its potential therapeutic molecular target development using solid tumor radioimmunotherapy.

Neuroendocrine tumours in 2012: Insights into signalling pathways could individualize therapy

Neuroendocrine tumours are a heterogeneous group of neoplasms with various clinical presentations, growth rates and responses to available therapies. Studies published in 2012 have provided insights into tumour-cell signalling that will increase our knowledge of tumour biology and molecular genetics, making it possible to personalize patient care.

Medical treatment of neuroendocrine tumours

PURPOSE OF REVIEW

This review summarizes results of recent clinical trials regarding the treatment of advanced neuroendocrine tumours (NETs) and pancreatic NETs (PNETs).

RECENT FINDINGS

Most NETs occur sporadically in the lung and the gastrointestinal tract, and their prevalence has apparently increased over the last decades. Although curative treatment can be accomplished by surgery, for some NETs, most present in advanced stages and alternative, medical therapy is indicated. Recent randomized clinical treatment trials using somatostatin analogues in well differentiated midgut NET and therapies targeting the mammalian target of rapamycin (mTOR) signalling pathway and various tyrosine kinases provided evidence of improved progression-free survival. Treatment of functional PNETs with the mTOR inhibitor everolimus also showed reduction of peptide secretion relevant to the presenting clinical syndrome.

SUMMARY

Previous work regarding the molecular pathology of NETs identified mTOR and tyrosine kinase signalling pathways as relevant targets in the neuroendocrine tumour biology. Subsequently, recent randomized clinical trials targeting these pathways with inhibitor therapies have provided encouraging results demonstrating prolonged progression-free survival and improvement of secretion-related clinical syndromes.

The phosphoinositide 3-kinase pathway is crucial for the growth of canine mast cell tumors

Mast cell tumors (MCTs) are the most common tumors in dogs, accounting for 16-21% of cutaneous tumors. Although several small molecule inhibitors, including imatinib mesylate, have been used for the treatment of MCTs, the response rate remains less than 50%. In this study, the effects of different selective signal inhibitors on MCT cell growth were evaluated using 4 different cell lines derived from dogs. We found that the phosphoinositide 3-kinase (PI3K) signaling pathway is crucial for the proliferation of MCT cells in the presence or absence of c-kit gene mutations. Here, we propose a novel therapeutic strategy to target the PI3K pathway for the treatment of canine MCTs.

Risk factors of peritoneal recurrence in eso-gastric signet ring cell adenocarcinoma: results of a multicentre retrospective study

INTRODUCTION

The poor prognosis of signet ring cell (SRC) eso-gastric adenocarcinoma (EGA) might be explained by its great affinity for the peritoneum. The aim of this study was to identify predictors of peritoneal carcinomatosis recurrence (PCR) after curative surgery and hence identify high risk patients.

METHODS

A retrospective national survey was conducted over 19 French surgical centers between 1997 and 2010. Patients with non-metastatic disease who benefited from curative surgery without postoperative death were included. Event-free patients who did not reach the time point of 24 months were excluded.

RESULTS

In a cohort of 3010 patients, 1050 were SRC EGA and 424 patients met the selection criteria. The tumor location was mainly gastric (68.9%) and a total gastrectomy was performed in 218 patients (51.4%). Chemoradiotherapy or chemotherapy alone was given preoperatively to 71 (16.7%) and postoperatively to 150 (35.4%) patients. After a median follow-up of 54 months, recurrence was diagnosed in 214 patients (50.5%) within a mean delay of 17 ± 10.7 months. PCR was diagnosed in 81 patients (19.1%). In multivariable analysis, four factors were identified as predictors of PCR: linitis plastica (p < 0.001; OR = 4.83), tumor invasion of/or through the peritoneal serosa (p = 0.022; OR = 1.58), lymph node involvement (p = 0.005; OR = 1.7) and tumors of gastric origin (p = 0.026; OR = 2.36), with PCR rates of 55%, 26%, 23% and 22%, respectively.

CONCLUSION

Identification of strong predictors for PCR among this large series of SRC EGA patients helps to identify subgroups of patients that may benefit from specific therapeutic strategies such as prophylactic hyperthermic intraperitoneal chemotherapy.

"Right drug for the right patient": hurdles and the path forward in colorectal cancer

Predictive biomarkers have been heralded as the way to develop the "right drug for the right patient." However, despite many studies incorporating novel biomarkers with targeted therapies, there has been little progress over the 5 years since the identification of KRAS mutations' ability to predict resistance to epidermal growth factor receptor (EGFR) monoclonal antibodies. Recently approved therapeutics (regorafenib, aflibercept) or label extensions for existing therapies (bevacizumab) lack companion biomarkers. The current model of biomarker development, "target-based biomarker" design, attempts to identify individual biomarkers that are closely tied to the activity of a particular treatment. There are several limitations to prospective utilization of predictive biomarkers in novel therapy development, including technical validation of the assay and the logistics of timely biomarker determination with available material that limit the options. Tumor heterogeneity, both between different regions in the tumor and as a result of changes induced over time and under the selective pressure of chemotherapy, can reduce the precision of biomarker determination. Biomarkers present in low frequencies are increasingly common in drug development and will require efficient screening infrastructure to be feasible. Although development efforts will continue in the current target-based biomarker model for the near future, it is increasingly apparent that a new model is needed. A "taxonomy-based biomarker" model has been proposed, which is less tied to novel drug development and instead attempts to classify individual tumors based on their intrinsic biology. This requires integrating multiple characteristics of the tumors, including gene mutations, amplifications, methylation, as well as RNA and protein expression. Identification of the taxonomy of colorectal cancer will then allow more efficient development of targeted agents that can leverage the distinct molecular vulnerabilities of the resulting subsets. A transition to a taxonomy-based biomarker model would provide the classification structure and biologic insights needed to advance the ultimate goal of the right drug for the right patient.

Antitumor effect of everolimus in preclinical models of high-grade gastroenteropancreatic neuroendocrine carcinomas

BACKGROUND/AIMS

While the range of therapeutic options for well-differentiated gastroenteropancreatic neuroendocrine tumors has recently increased with the emergence of targeted therapies, such as mTOR inhibitors, there is no recent progress in the treatment of poorly differentiated neuroendocrine carcinomas (PDNECs). Since PDNECs have been shown to strongly express mTOR pathway components, the aim of the present study was to assess the antitumor effect of the mTOR inhibitor everolimus in preclinical models of PDNECs.

METHODS

The expression of mTOR pathway components and their response to everolimus were assessed in two neuroendocrine cell lines: STC-1 and GluTag. A xenograft model of intrahepatic dissemination in the nude mouse, based on the intrasplenic injection of either STC-1 and GluTag tumor cells, was used. Animals were started on everolimus treatment 3 days after injection. The effects of treatment on tumor growth, proliferative capacities, apoptosis and in situ expression of mTOR pathway components were assessed.

RESULTS

The expression of mTOR pathway components was comparable in STC-1 and GluTag cells and in human PDNECs and could be inhibited in vitro by everolimus. In vivo, the tumor volume of STC-1 and GluTag xenografts was significantly reduced in treated animals (6.05 ± 1.84% as compared to 21.76 ± 3.88% in controls). Everolimus treatment also induced a significant decrease in Ki67 index and in the phosphorylation levels of the two major effectors of mTOR, p70S6K and 4E-BP1.

CONCLUSION

Our experimental data suggest that mTOR inhibition could be considered a therapeutic option for high-grade gastroenteropancreatic neuroendocrine tumors.

[Advanced research of mTOR and lung carcinoid tumors]

Mammalian target of rapamycin (mTOR), a main protein kinase in the phosphoinositide 3-kinase (PI3K)/AKT/mTOR signaling pathway, is an important intracellular mediator involved in multiple celluar functions including proliferation, differentiation, apoptosis, tumorigenesis, and angiogenesis. Recently, the high expression of mTOR and mTOR-related kinase have been found in neuroendocrin tumors. Therefore, mTOR pathway represents an attractive target for new anticancer therapies except surgery.

Improving the diagnosis and management of neuroendocrine tumors: utilizing new advances in biomarker and molecular imaging science

Neuroendocrine tumors (NET) are malignant solid tumors that arise in hormone-secreting tissue of the diffuse neuroendocrine system or endocrine glands. Although traditionally understood to be a rare disease, the incidence and prevalence of NET have increased greatly in the past 3 decades. However, during this time, progress in diagnosis and outcome of NET has generally been modest. In order to achieve improved outcome in NET, a better understanding of NET biology combined with more reliable serum markers and better techniques to identify tumor localization and small lesions are needed. Although some NET biomarkers exist, sensitive and specific markers that predict tumor growth and behavior are generally lacking. In addition, the integration of new molecular imaging technologies in patient diagnosis and follow-up has the potential to enhance care. To discuss developments and issues required to improve diagnostics and management of NET patients, with specific focus on the latest advances in molecular imaging and biomarker science, 17 global leaders in the fields of NET, molecular imaging and biomarker technology gathered to participate in a 2-day meeting hosted by Prof. Kjell Öberg at the University of Uppsala in Sweden. During this time, findings were presented regarding methods with potential prognostic and treatment applications in NET or other types of cancers. This paper describes the symposium presentations and resulting discussions.

Treatment of metastatic neuroendocrine tumors of the thymus with capecitabine and temozolomide: a case series

BACKGROUND

Metastatic neuroendocrine tumors of the thymus are exceedingly rare with an annual incidence of approximately 0.2 per 1,000,000. They are highly resistant to therapy and there have been no reports of an objective radiographic response to treatment.

MATERIALS AND METHODS

The authors retrospectively evaluated 3 patients with progressive, metastatic neuroendocrine tumors of the thymus who were treated with a combination of capecitabine and temozolomide. Radiographic scans were evaluated and response assessed using RECIST criteria.

RESULTS

One patient experienced a partial radiographic response, another patient experienced a minor response and the third patient experienced stable disease as the best response to treatment.

CONCLUSION

The combination of capecitabine and temozolomide appears to be active in a rare neuroendocrine malignancy that is generally refractory to systemic therapy. Prospective multicenter trials are needed to validate this strategy.

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.

Risk of de novo cancers after transplantation: results from a cohort of 7217 kidney transplant recipients, Italy 1997-2009

To assess incidence and risk factors for de novo cancers (DNCs) after kidney transplant (KT), we carried out a cohort investigation in 15 Italian KT centres. Seven thousand two-hundred seventeen KT recipients (64.2% men), transplanted between 1997 and 2007 and followed-up until 2009, represented the study group. Person years (PY) were computed from 30 days after transplant to cancer diagnosis, death, return to dialysis or to study closure. The number of observed DNCs was compared to that expected in the general population of Italy through standardised incidence ratios (SIR) and 95% confidence intervals (CI). To identify risk factors, incidence rate ratios (IRR) were computed. Three-hundred ninety five DNCs were diagnosed during 39.598PYs, with Kaposi's sarcoma (KS), post-transplant lymphoproliferative disorders (PTLD), particularly non-Hodgkin' lymphoma (NHL), lung, kidney and prostate as the most common types. The overall IR was 9.98/1.000PY, with a 1.7-fold augmented SIR (95% CI: 1.6-1.9). SIRs were particularly elevated for KS (135), lip (9.4), kidney carcinoma (4.9), NHL (4.5) and mesothelioma (4.2). KT recipients born in Southern Italy were at reduced risk of kidney cancer and solid tumors, though at a higher KS risk, than those born in Northern Italy. Use of mTOR inhibitors (mTORi) exerted, for all cancers combined, a 46% significantly reduced risk (95% CI: 0.4-0.7). Our study findings confirmed, in Italy, the increased risks for cancer following KT, and they also suggested a possible protective effect of mTORi in reducing the frequency of post transplant cancers.

The effects of ERCC1 expression levels on the chemosensitivity of gastric cancer cells to platinum agents and survival in gastric cancer patients treated with oxaliplatin-based adjuvant chemotherapy

Excision repair cross-complementing 1 (ERCC1) is reported to be involved in the sensitivity of cancer cells to platinum-based chemotherapy. The present study was designed to evaluate the effects of ERCC1 expression on the chemosensitivity of platinum agents in gastric cancer cell lines, and on survival in gastric cancer patients treated with surgery followed by oxaliplatin-based adjuvant chemotherapy. ERCC1 expression levels were measured by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and western blot analysis, respectively. The chemosensitivity of a series of gastric cancer cell lines to platinum agents in vitro was evaluated using CellTiter 96 Aqueous One Solution Cell Proliferation Assay kit. The apoptotic effect of the drugs was evaluated by double staining with Annexin-V-fluorescein isothiocyanate (FITC) and propidium iodide (PI). The results demonstrated that the expression levels of ERCC1 mRNA were correlated with the chemosensitivity of platinum agents, and depletion of ERCC1 sensitized the relatively resistant MKN45 cells to cisplatin and oxaliplatin. Univariate analyses revealed that patients with low ERCC1 levels had longer relapse-free survival (RFS) and overall survival (OS) than those with high ERCC1 levels (median RFS, 18 vs. 7 months, P=0.001; median OS, 27 vs. 11 months, P=0.001). Multivariate analyses suggested that high ERCC1 expression is an independent prognostic marker of poor RFS [hazard ratio (HR), 2.16; 95% confidence interval (CI), 1.09–4.25; P= 0.026] and OS (HR, 2.21; 95% CI, 1.07–4.55; P=0.031). These results suggest that overexpression of ERCC1 is correlated with platinum drug resistance in gastric cancer cells, and that depletion of ERCC1 sensitizes gastric cancer cell lines to cisplatin and oxaliplatin. Gastric cancer patients with low levels of ERCC1 expression demonstrate a benefit from oxaliplatin-based adjuvant chemotherapy.

A phase I study of sorafenib, oxaliplatin and 2 days of high dose capecitabine in advanced pancreatic and biliary tract cancer: a Wisconsin oncology network study

Chemotherapy has yielded minimal clinical benefit in pancreatic and biliary tract cancer. A high-dose, short course capecitabine schedule with oxaliplatin, has shown some efficacy with a lower incidence of palmar-plantar erythrodysesthesia. Achieving high exposures of the targeted agent sorafenib may be possible with this shorter schedule of capecitabine by avoiding dermatologic toxicity. All patients had pancreatic or biliary tract cancer. Patients in both cohorts received oxaliplatin 85 mg/m2 followed by capecitabine 2,250 mg/m2 PO every 8 h x 6 doses starting on days 1 and 15 of a 28 day cycle, or 2DOC (2 Day Oxaliplatin/Capecitabine). Cohort 1 used sorafenib 200 mg BID, and cohort 2 used sorafenib 400 mg BID. Sixteen patients were enrolled. Across all cycles the most common grade 1 or 2 adverse events were fatigue (10 pts), diarrhea (10 pts), nausea (9 pts), vomiting (8 pts), sensory neuropathy (8 pts), thrombocytopenia (7 pts), neutropenia (5 pts), and hand-foot syndrome (5 pts). Grade 3 toxicites included neutropenia, mucositis, fatigue, vomiting and diarrhea. Cohort 1 represented the MTD. Two partial responses were seen, one each in pancreatic and biliary tract cancers. The recommended phase II dose of sorafenib in combination with 2DOC is 200 mg BID. There were infrequent grade 3 toxicities, most evident with sorafenib at 400 mg BID.

Everolimus plus octreotide long-acting repeatable in patients with colorectal neuroendocrine tumors: a subgroup analysis of the phase III RADIANT-2 study

INTRODUCTION

The incidence of colorectal neuroendocrine tumors (NETs) is increasing, and patients with this disease have particularly poor prognoses. Treatment options are limited, and survival times have not improved in the past decade.

METHODS

A post hoc analysis of the efficacy and tolerability of everolimus plus octreotide long-acting repeatable (LAR) was conducted in patients with colorectal NETs enrolled in the phase III RAD001 in Advanced Neuroendocrine Tumors, Second Trial (RADIANT-2) study. The primary endpoint (progression-free survival [PFS]), secondary endpoints (including objective response rate), and safety were assessed.

RESULTS

Patients with colorectal NETs receiving everolimus plus octreotide LAR had a significantly longer median PFS (29.9 months; n = 19) than did those receiving placebo plus octreotide LAR (6.6 months; n = 20). Everolimus plus octreotide LAR treatment also significantly reduced the risk for disease progression (hazard ratio: 0.34; 95% confidence interval: 0.13-0.89; p = .011). Although no objective responses were observed, tumor shrinkage was more frequently noted in the everolimus plus octreotide LAR arm than in the placebo plus octreotide LAR arm (67% vs. 37%, respectively). The combination of everolimus plus octreotide LAR was generally well tolerated by patients with colorectal NETs; rash and stomatitis were the most commonly reported adverse events.

CONCLUSIONS

Everolimus plus octreotide LAR treatment had significant benefits and improved outcomes for patients with advanced colorectal NETs compared with placebo plus octreotide LAR treatment. Results of this exploratory analysis are consistent with those reported from the RADIANT-2 primary analysis. These findings support additional investigations of everolimus plus octreotide LAR in patients with colorectal NETs.

Novel molecular targets for the treatment of gastroenteropancreatic endocrine tumors: answers and unsolved problems

As more knowledge on molecular alterations favoring carcinogenesis and spreading of gastroenteropancreatic endocrine tumors has become available, a number of targeted agents interfering with key growth and angiogenic pathways have been explored in preclinical and clinical studies. The mTOR inhibitor Everolimus, and the multi-target antiangiogenetic agent Sunitinib, have been shown to be effective and thus have been approved by the FDA for treatment of pancreatic endocrine tumors. However, there is little data on the primary resistance to targeted agents on these tumors. The goals of the present review are to elucidate the possible advantage of combined treatments in overcoming induced resistances, and to identify biomarkers able to predict clinical efficacy. Moreover, the role of interesting targets for which a strong biological rationale exists, and specific inhibitors are available, such as the Src Family Kinases and the Hedgehog Pathway, are discussed. There is now need for more preclinical studies on cell lines and animal models to provide a stronger preclinical background in this field, as well as clinical trials specifically comparing one targeted therapy with another or combining different targeted agents.