PI3K-AKT-mTOR pathway and cancer

PI3K/AKT/mTOR pathway is an intracellular signalling pathway composed of different kinases. Many protein mutations are described in that pathway, and are responsible of dysregulation of cell growth, proliferation, survival and angiogenesis. Rapamycin is an antibiotic inhibiting mTOR. Different analogs of rapamycin are developed or being developed in antitumoral therapy, in which temsirolimus, everolimus and deforolimus, demonstrated antitumoral activity in renal cancer and mantle cell lymphoma, and many clinical trials are in progress in other tumors. In the future, predictive factors of response need to be identified; patient selection and associations with chemotherapy or with other targeted therapies should be explored.     

Histone deacetylase inhibitors in the treatment of hematological malignancies

Histone deacetylases inhibitors (HDACi) represent a new epigenetic targeting therapy class, which is widely investigated in fundamental research and clinical trials. They are able to restore and increase tumor suppressor genes expression and to play an anti-tumoral activity through numerous targets, which are distributed all over the main differentiation, proliferation and survival cellular pathways. Their use in hematology led to vorinostat (SAHA) and romidepsin approval by FDA for the treatment of refractory cutaneous T-cell lymphomas. Preclinical and preliminary clinical results show a promising antineoplasic activity in most hematologic malignancies. This review will focus on the HDACi recent developments and current investigations, highlighted by recent communications.     

Risk of infections in renal cell carcinoma (RCC) and non-RCC patients treated with mammalian target of rapamycin inhibitors

Background:

Mammalian target of rapamycin (mTOR) inhibitors are used in a variety of malignancies. Infections have been reported with these drugs. We performed an up-to-date meta-analysis to further characterise the risk of infections in cancer patients treated with these agents.

Methods:

Pubmed and oncology conferences'' proceedings were searched for studies from January 1966 to June 2012. Studies were limited to phase II and III randomised controlled trials (RCTs) of everolimus or temsirolimus reporting on cancer patients with adequate safety profiles. Summary incidences, relative risks (RRs), and 95% confidence intervals (CIs) were calculated.

Results:

A total of 3180 patients were included. The incidence of all-grade and high-grade infections due to mTOR inhibitors was 33.1% (95% CI, 24.5–43.0%) and 5.6% (95% CI, 3.8–8.3%), respectively. Compared with controls, the RR of all-grade and high-grade infections due to mTOR inhibitors was 2.00 (95% CI, 1.76–2.28, P<0.001) and 2.60 (95% CI, 1.54–4.41, P<0.001), respectively. Subgroup analysis found no difference in incidences or risks between everolimus and temsirolimus or between different tumour types (renal cell carcinoma (RCC) vs non-RCC). Infections included respiratory tract (61.7%), genitourinary (29.4%), skin/soft tissue (4.2%), and others (4.9%).

Conclusion:

Treatment with mTOR inhibitors is associated with a significant increase in risk of infections. Close monitoring for any signs of infections is warranted.     

Prise en charge des troubles métaboliques observés avec évérolimus chez les patients atteints de tumeurs neuroendocrines bien différenciées non résécables : propositions d’experts

Medical management of pancreatic neuroendocrine tumors has recently been improved by new molecules of which the mTOR inhibitor everolimus. If digestive neuroendocrine tumors are rare, the incidence is in constant increase and the prevalence in digestive cancers put them right behind colorectal cancers. Everolimus has demonstrated efficacy in unresectable and progressive pancreatic neuroendocrine tumors, by doubling the median progression free survival (11 versus 4.6 months), with a median time of exposure to everolimus of nine months. Everolimus is generally maintained until progression or intolerance and some patients are treated during several years. Potential metabolic disorders induced by everolimus (dyslipidemia, hyperglycemia) in patients with life expectancy of several years, justify monitoring of these parameters and accurate treatment management algorithm. These will avoid worsening patient's prognostic, but also prematurely discontinue potentially effective treatment or contraindicate other therapeutic weapons, in a pathology in which there are multiple therapeutic options in metastatic phase. We propose a standard practice in terms of initial assessment, monitoring, care threshold, and therapeutic objectives to manage metabolic disorders, fitted to our patients with advanced pancreatic neuroendocrine tumors.     

Antihormonal therapy in breast cancer and mTOR inhibitors

Hormonal dependence of breast cancer has been known for a long time, yet about half of breast cancers with estrogen receptor will not respond to antihormonal therapy. Now, we know that this resistance may be related to a dysfunction of the estrogen pathway, or that of growth factors and particularly the pathway of cell activation PI3K/Akt/mTOR. Prevention of these different mechanisms of resistance could involve combination therapies such as anti-estrogens (SERMs, aromatase inhibitors) with inhibitors of the activity of growth factors that are particularly temsirolimus and everolimus for the activation pathway cell PI3K/Akt/mTOR.     

New developments in mammalian target of rapamycin inhibitors for the treatment of sarcoma

Although sarcomas account for a small portion of solid malignancies, currently, there are few treatment options for sarcomas, particularly for advanced disease. The mammalian target of rapamycin (mTOR), a serine-threonine protein kinase in the phosphatidylinositol 3-kinase/serine/threonine protein kinase Akt signaling pathway, has an important role in the regulation of protein synthesis, cell proliferation, angiogenesis, and metabolism. Alterations of the mTOR signaling pathway are common in malignancies, including several types of sarcoma. Therefore, mTOR is a potentially important therapeutic target in these diseases. Rapamycin and its analogs (rapalogs) are effective anticancer agents in a broad range of preclinical models. Clinical trials with these agents alone and in combination with other anticancer agents, including chemotherapy and targeted therapies, have demonstrated potential clinical benefit in several types of sarcoma. The evidence from both preclinical and clinical studies supports further study of mTOR-targeting rapalogs in the treatment of various subtypes of sarcoma.     

The clinical potential of temsirolimus in second or later lines of treatment for metastatic renal cell carcinoma

An impressive variety of targeted therapies has been approved for the treatment of metastatic renal cell carcinoma (mRCC). Despite promising progress, there are still unmet clinical needs. The optimal sequence of these agents in the therapeutic setting has not yet been determined. Most available data address first- and second-line therapy of clear cell RCC. The mTOR inhibitor temsirolimus has been approved for first-line treatment of mRCC, and there are new data addressing the use of temsirolimus in later therapeutic lines. Temsirolimus has discerning features compared with other currently registered drugs, such as its intravenous administration route–providing predictable bioavailability and adherence to treatment–and potential benefit in nonclear cell histologies. Here, we review the available literature on temsirolimus, with reference to data also available for everolimus, to determine its clinical potential in mRCC.     

The role of mTOR inhibition as second-line therapy in metastatic renal carcinoma: clinical evidence and current challenges

Introduction: Sequential treatment with targeted agents is the standard of care for patients with metastatic renal cell carcinoma (mRCC). Although first-line therapy with tyrosine kinase inhibitors (TKIs) is recommended for most patients, eventually all patients become resistant to them. Therefore, optimal selection of second-line therapy is crucial.

Areas covered: We have reviewed the recent literature through pubmed search and recent congress presentations to briefly describe the clinical evidence for mTOR inhibition as a valid strategy in the treatment of mRCC after progression during anti-VEGFR therapy. In addition, we outline the management of adverse events associated with these agents, highlighting the importance of switching to an alternative mechanism of action to overcome resistance to TKI and to decrease cumulative toxicity associated with sequential treatments of the same type.

Expert commentary: The choice of subsequent therapy after progression to first-line is not clear. Although the new drugs cabozantinib and nivolumab have shown to be superior that everolimus, still it is unknown which patients may benefit from these therapies in second-line, so treatment should be personalized to each patient and should consider approaches with different mechanisms of action.     

Clinical and histopathologic characteristics of rash in cancer patients treated with mammalian target of rapamycin inhibitors

BACKGROUND:

Dermatologic adverse events stemming from anticancer therapies have become an increasingly frequent clinical problem. Inhibitors of mammalian target of rapamycin (mTOR), such as temsirolimus and everolimus, have been associated with a high rate of skin eruptions, but their clinical and histopathologic characteristics have not been explored.

METHODS:

A retrospective analysis of patients who were referred to the Dermatology Service for diagnosis and management of rash in the setting of therapy with the mTOR inhibitors everolimus and temsirolimus was performed. The parameters that were studied included the time to onset, clinical presentation at the time of dermatologic evaluation, associated symptoms, evolution, results of microbiologic studies, concomitant medications, the need for dose reduction and/or treatment interruption because of rash, and routine histopathology.

RESULTS:

In total, 13 patients were analyzed. Most rashes were mild (grade 1; 31%) and moderate (grade 2; 54%) in severity, and grade 3 rashes were observed only in 2 patients (15%). The trunk was the most frequently affected region (77%), with the scalp (23%), face (38%), neck (54%), and extremities (69%) also commonly involved. Erythematous papules and pustules constituted the predominant primary lesion morphology (62%). No unique or uniform histopathologic reaction pattern was observed. The most common reaction pattern was that of a mixed, spongiotic interface and perivascular dermatitis, which was observed in 7 of 11 patients (63%).

CONCLUSIONS:

Although mTOR inhibitors may commonly induce erythematous papules and pustules, they are associated with a spectrum of lesion morphologies and a variety of histopathologic findings. Further clinicohistologic correlation studies are needed. Cancer 2012. © 2012 American Cancer Society.     

Aspects of mTOR biology and the use of mTOR inhibitors in non-Hodgkin's lymphoma

The mammalian target of rapamycin (mTOR) is a large and highly conserved kinase that integrates growth factor stimulation, energy and nutrient availability to modulate translation of proteins responsible for cellular growth and proliferation. Its importance in malignant cells provides strong rationale for the development of mTOR inhibitors (mTORi) in a broad variety of solid tumors and hematological malignancies. However several questions regarding mTOR biology and its interaction with pharmacological inhibitors remain unanswered and are relevant for further development of this novel family of cancer drugs. Nevertheless, mTORi have demonstrated activity in lymphoma cells either alone or in combination with cytotoxic agents. The most promising results have been seen in mantle cell lymphoma (MCL), likely because of its dependence on Cyclin D, the translation of which is largely regulated by mTOR activity. The currently knowledge of mTOR biology will here be reviewed along with the status of clinical development of mTORi in non-Hodgkin's lymphomas.     

Advances in mechanisms of resistance to aromatase inhibitors

Clinically, there are two distinct types of aromatase inhibitor (AI) resistance, namely acquired and innate resistance. Because the underlying mechanisms of these two types of resistance may not be mutually exclusive, strategies to tackle these resistances may not be effective when used interchangeably. Activation of growth factor receptor pathways is the hallmark of acquired AI resistance. These pathways can be targeted either at the cell surface receptor level or their downstream signaling cascades. Currently, everolimus in combination with exemestane represents a new standard of care for patients progressing on non-steroidal AIs. HDAC inhibitors have also shown promising results For innate resistance, the combination of fulvestrant and AI in the front line setting represents a new treatment option, particularly for patients who present with de novo metastatic disease. A Phase III trial is currently ongoing to evaluate the benefit of CDK 4/6 inhibitor, palbociclib, in the first line setting in combination with AI.     

Noninfectious pneumonitis with the use of mTOR inhibitors in breast cancer

The mammalian target of rapamycin (mTOR) inhibitor class of drugs represents the newest addition to the armamentarium of therapies for hormonally driven breast cancer. It has recently been shown that the addition of mTOR inhibitor everolimus to aromatase inhibitors in hormone receptor–positive breast cancers improves progression-free survival. However, a clinically significant toxicity associated with this class of drugs is the development of noninfectious pneumonitis (NIP). Although generally mild and manageable, everolimus-induced NIP requires prompt diagnosis and management. This article will provide a brief overview of data relating to dysregulation of the phosphatidylinositol-3-kinase/protein kinase B/mTOR pathway in breast cancer; review the literature relating to the efficacy and safety of mTOR inhibitors in breast cancer; and evaluate the incidence, severity, and optimal management of mTOR inhibitor–related NIP in breast cancer.     

Antifungal treatment strategies in patients with haematological diseases or cancer: from prophylaxis to empirical, pre-emptive and targeted therapy

Immunocompromised patients have a high risk for invasive fungal diseases (IFDs). These infections are mostly life-threatening and an early diagnosis and initiation of appropriate antifungal therapy are essential for the clinical outcome. Empirical treatment is regarded as the standard of care for granulocytopenic patients who remain febrile despite broad-spectrum antibiotics. However, this strategy can bear a risk of overtreatment and subsequently induce toxicities and unnecessary treatment costs. Pre-emptive antifungal therapy is now increasingly used to close the time gap between delayed initiation for proven disease and empirical treatment for anticipated infection without further laboratory or radiological evidence of fungal disease. Currently, some new non-invasive microbiological and laboratory methods, like the Aspergillus-galactomannan sandwich-enzyme immunoassay (Aspergillus GM-ELISA), 1,3-β-D-glucan assay or PCR techniques have been developed for a better diagnosis and determination of target patients. The current diagnostic approaches to fungal infections and the role of the revised definitions for invasive fungal infections, now IFDs, will be discussed in this review as well as old and emerging approaches to empirical, pre-emptive and targeted antifungal therapies in patients with haemato-oncological malignancies.     

Inhibition of mTOR pathway by everolimus cooperates with EGFR inhibitors in human tumours sensitive and resistant to anti-EGFR drugs

Inhibition of a single transduction pathway is often inefficient due to activation of alternative signalling. The mammalian target of rapamycin (mTOR) is a key intracellular kinase integrating proliferation, survival and angiogenic pathways and has been implicated in the resistance to EGFR inhibitors. Thus, mTOR blockade is pursued to interfere at multiple levels with tumour growth. We used everolimus (RAD001) to inhibit mTOR, alone or in combination with anti-EGFR drugs gefitinib or cetuximab, on human cancer cell lines sensitive and resistant to EGFR inhibitors, both in vitro and in vivo. We demonstrated that everolimus is active against EGFR-resistant cancer cell lines and partially restores the ability of EGFR inhibitors to inhibit growth and survival. Everolimus reduces the expression of EGFR-related signalling effectors and VEGF production, inhibiting proliferation and capillary tube formation of endothelial cells, both alone and in combination with gefitinib. Finally, combination of everolimus and gefitinib inhibits growth of GEO and GEO-GR (gefitinib resistant) colon cancer xenografts, activation of signalling proteins and VEGF secretion. Targeting mTOR pathway with everolimus overcomes resistance to EGFR inhibitors and produces a cooperative effect with EGFR inhibitors, providing a valid therapeutic strategy to be tested in a clinical setting.     

Potential clinical impact of therapeutic education in patients treated with anticancer drugs

The aim of our work was to assess the potential clinical impact of therapeutic education in patients treated with anticancer drugs. One hundred-one ambulatory adult patients (mean age: 60 years, range: 24-88) treated by anticancer chemotherapy were included. The occurrence of adverse events was reported by 83% of the patients. Twenty-one percent (14/67) of the patients were not compliant with their supportive care treatment, 60% (60/101) took over-the-counter medications (one contraindication identified) and 14% (14/101) claimed they had received no counsel on risk behaviour (UV exposure, lack of contraception, driving) from health care professionals. Overall, 11% (44/397) of adverse events were associated with a lack of information. Twelve percent (4/33) of the calls to the doctor, 6% (1/17) of the visits to the physician and 21% (3/14) of the hospitalizations could be associated with a lack of therapeutic education. These data enlighten the importance of therapeutic education of cancer patients treated by chemotherapy.     

A phase II trial of everolimus,temozolomide, and radiotherapy in patients with newly diagnosed glioblastoma: NCCTG N057K

BackgroundThe mammalian target of rapamycin (mTOR) functions within the phosphatidylinositol-3 kinase (PI3K)/Akt pathway as a critical modulator of cell survival. This clinical trial evaluated the combination of the mTOR inhibitor everolimus with conventional temozolomide (TMZ)-based chemoradiotherapy.MethodsNewly diagnosed patients with glioblastoma multiforme were eligible for this single arm, phase II study. Everolimus (70 mg/wk) was started 1 week prior to radiation and TMZ, followed by adjuvant TMZ, and continued until disease progression. The primary endpoint was overall survival at 12 months, and secondary endpoints were toxicity and time to progression. Eleven patients were imaged with 3′-deoxy-3′-¹⁸F-fluorothymidine (¹⁸FLT)–PET/CT before and after the initial 2 doses of everolimus before initiating radiation/TMZ. Imaged patients with sufficient tumor samples also underwent immunohistochemical and focused exon sequencing analysis.ResultsThis study accrued 100 evaluable patients. Fourteen percent of patients had grade 4 hematologic toxicities. Twelve percent had at least one grade 4 nonhematologic toxicity, and there was one treatment-related death. Overall survival at 12 months was 64% and median time to progression was 6.4 months. Of the patients who had ¹⁸FLT-PET data, 4/9 had a partial response after 2 doses of everolimus. Focused exon sequencing demonstrated that ¹⁸FLT-PET responders were less likely to have alterations within the PI3K/Akt/mTOR or tuberous sclerosis complex/neurofibromatosis type 1 pathway compared with nonresponders.ConclusionCombining everolimus with conventional chemoradiation had moderate toxicity. ¹⁸FLT-PET studies suggested an initial antiproliferative effect in a genetically distinct subset of tumors, but this did not translate into an appreciable survival benefit compared with historical controls treated with conventional therapy.     

Major therapeutic advances in the treatment of metastatic melanoma

The treatment of metastatic melanoma is presently in complete revolution. Two molecules have recently been authorized for this indication. These treatments have a very different mechanism of action compared to previous chemotherapies. Vemurafenib is a targeted therapy, which blocks BRAF selectively. This molecule induces objective responses in more than 50 % of the patients with V600E mutated melanoma and a benefit in terms of overall survival. However, many patients relapse after about 6 to 8 months of treatment. Many mechanisms are evoked to explain these secondary resistances to therapy. Ipilimumab is an immunotherapy that blocks CTLA4, a physiological brake of lymphocyte activation. With ipilimumab, the objective responses are less frequent than with vemurafenib but are more prolonged over time. Two phases III have demonstrated that ipilimumab treatment is effective on the overall survival of patients with metastatic melanoma. New combination therapies and additional targeted and immunotherapy agents are exciting perspectives that make us more optimistic for the future of metastatic melanoma treatment.     

Developments in the use of tyrosine kinase inhibitors in the treatment of renal cell carcinoma

Introduction: Renal cell carcinoma (RCC) is among the most commonly diagnosed solid malignancies, but until recently there were few systemic treatment options for advanced disease. Since 2005, the treatment landscape has been transformed by the development of several novel systemic therapies. In particular, tyrosine kinase inhibitors (TKIs) targeting the vascular endothelial growth factor (VEGF) pathway have been instrumental in improving outcomes in patients with metastatic disease.

Areas covered: The armamentarium of TKIs available for the treatment of RCC has expanded in recent years. The most active area of research at this time is the development of treatment regimens combining newer-generation TKIs and immune checkpoint inhibitors. Emerging data point to a role for combination therapy in the frontline management of advanced RCC. Other ongoing areas of research include the use of TKIs in the adjuvant setting and the role of cytoreductive nephrectomy within a changing treatment landscape.

Expert opinion: Although TKIs and immune checkpoint inhibitors have incrementally improved outcomes for patients with advanced RCC, long-term survival remains poor. The development of regimens combining these agents represents the next step in the evolution of the field. For the clinician, this will offer exciting possibilities and novel challenges.     

乳腺癌芳香化酶抑制剂治疗的现状与存在问题

当前乳腺癌内分泌治疗的重大进步是新一代芳香化酶抑制剂（AIs）的研发使用。从1998年开始,先后有第二代的兰他隆（福美斯坦）、第三代的弗隆（来曲唑）、瑞宁得（阿那曲唑）、阿诺新（依西美坦）等在我国临床应用,正确的内分泌治疗理念也随之为大家逐渐接受。