**BIOTECH AND PHARMA NEWS**

[Preciouslife1]

Protease inhibitors

The HCV NS3-4A serine protease has long been a desirable drug target for HCV; however, its shallow active binding site has made it difficult to design small-molecule inhibitors. Boehringer Ingelheim's BILN 2061 was the first to enter the clinic and although Phase I results were highly promising, further clinical development of this compound was halted because of cardiotoxicity in animals1.
Two other protease inhibitors are now in the clinic — Vertex's VX-950 and Schering-Plough's SCH-503034. VX-950 has shown significant potency in a 14-day Phase I trial in treatment-naive patients, either administered alone or in combination with PEG–IFN. Twelve out of twelve patients achieved undetectable levels of HCV RNA after 28 days of VX-950 and PEG–IFN and ribavirin treatment. Building on this success, the current Phase II trials are investigating 3 months of treatment with VX-950 in combination with PEG–IFN with or without ribavirin. Results are expected in late 2006.
The development of SCH-503034 has taken a different path, initially focusing on treatment non-responders. Phase I trials have indicated that the drug is not as potent as VX-950 at the doses tested so far, but higher doses are being tested in combination with PEG-Intron (Schering-Plough), with or without ribavirin in an ongoing 48-week Phase II trial. InterMune's ITMN-191 looks set to be the third protease inhibitor to enter the clinic (by year end).
Resistant variants have been identified to all these drugs in vitro and in vivo (except ITMN-191), though genotyping of patients in clinical trials has yet to show that selection of these variants (and/or others) leads to viral breakthrough. Longer trials will determine whether drug resistance is as valid a concern as it is in HIV.
Immunomodulators

Most experts agree that for the foreseeable future, HCV treatment regimens are likely to include an immunomodulator. Newer forms of IFN, such as Human Genome Sciences/Novartis' Albuferon (in Phase II) and Biolex/OctoPlus' Locteron (in Phase I), seek to reduce the frequency of dosing from once a week to once every 2 weeks and potentially once a month.
Newer approaches include the Toll-like receptor (TLR) agonists, a class of small molecules that specifically stimulate the innate immune system. In the clinic, TLR agonists include Coley's Actilon (CPG10101), a TLR9 agonist in Phase II, and Anadys' ANA-975, a TLR7 agonist in Phase I. Early results have shown signs of antiviral activity, although in the case of ANA-975 dosing was halted after preclinical data suggested prolonged dosing (13+ weeks) led to adverse events caused by intense immunological stimulation.
Future perspectives

It is evident that the way in which HCV is treated is about to change as new drugs edge towards the market. The protease inhibitors could have the greatest impact on treatment given their potential to shorten the duration of therapy, but many physicians remain cautious. SVR rates need to be improved, the holy grail being an all oral drug combination that pushes rates into the 80–90% range without the need for IFN injections. This goal remains some distance away, but in the meantime the current treatment market for HCV is likely to grow from US$3 billion per year to more than $8 billion by 2010 (Fig. 3).
Figure 3 | Current and forecasted market shares of hepatitis C treatment classes.

• <LI class=high-res minmax_bound="true">High resolution image and legend (17 KB) <LI class=fti minmax_bound="true">Figures and tables index
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Market indicators

The market for the treatment of hepatitis C virus is set to rapidly expand in the coming years as new and more effective therapies enter the market (Table 1 and Fig. 3). We believe that only a fraction of patients diagnosed with a chronic HCV infection currently receive some form of treatment. Although the initial batch of antivirals are likely to be used in combination with the undesirable combination of PEG–IFN and ribavirin, we anticipate the potential for higher SVR rates than current treatments (Fig. 2), and shorter treatment durations will make these new treatment options more appealing to patients and help improve treatment rates.
Table 1 | Selected late-stage hepatitis C drugs

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References

1. Lamarre, D. et al. An NS3 protease inhibitor with antiviral effects in humans infected with hepatitis C virus. Nature 426, 186–189 (2003).

1. Shaw-Stiffel, T. & Kim, W. R. Global epidemiology and burden of hepatitis C. Microbes Infect. 4, 1219–1225 (2002).

Links

FURTHER INFORMATION

• <LI class=first minmax_bound="true">Centers for Disease Control—Hepatitis C virus
• Hepatitis C virus treatments

[Preciouslife1]

Decidedly different

/**/ A new study shows that differing lesions cooperate oncogenically with Myc by discrete mechanisms that can themselves synergize with each other.
The aberrant expression of oncogenes induces tumour development, but it also triggers apoptosis or cell-cycle arrest. So, cooperating mutations are needed to overcome these barriers, but which is more cooperative: loss of apoptosis or loss of cell-cycle arrest?
Previous work from Gerard Evan's group has shown that the activation of a regulatable form of the MYC protein (MYC–ERTAM) in the insulin-secreting -islet cells (cells) of the pancreas (plns–Myc–ERTAM mice) results in the apoptosis of these cells. Inhibiting MYC-induced apoptosis through the expression of the anti-apoptotic protein BCL-XL results in an increase in cell numbers.
Other mutations, such as the loss of the tumour suppressors ARF or p53 also cooperate with MYC, but do they also work by suppressing MYC-induced apoptosis? Evan's group crossed the plns–Myc–ERTAM mice with Arf-/- or Trp53-/- mice. Surprisingly, the -cells of the plns–Myc–ERTAM/Arf-/- mice had higher rates of MYC-induced apoptosis than plns–Myc–ERTAM mice, and higher rates of proliferation than the -cells that expressed both MYC–ERTAM and BCL-XL. However, this increased proliferation in the plns–Myc–ERTAM/Arf-/- mice did not cause an expansion of the -cell population owing to the high levels of apoptosis. -cells from the plns–Myc–ERTAM/Trp53-/- mice showed an increased rate of proliferation similar to the plns–Myc–ERTAM/ Arf-/- mice, but rates of apoptosis were lower in this case than in plns–Myc–ERTAM mice.
The aberrant expression of MYC normally induces the expression of ARF, which leads to the stabilization of p53, expression of the anti-proliferative, cyclin-dependent-kinase inhibitor p21 and the induction of apoptosis. The expression of p21 does not occur in the Arf or Trp53 knockout cells, which leaves MYC-induced proliferation unchecked, but apoptosis is not affected. These data imply several important points. First, that ARF limits the oncogenicity of MYC by inhibiting proliferation; second, that this is p53 dependent; and third, that ARF does not limit the oncogenicity of MYC by inducing apoptosis. The lack of p21 expression also explains the increased proliferation in the plns–Myc–ERTAM/Trp53-/- mice. The authors suggest that MYC-induced apoptosis is partially inhibited in the p53-deficient mice because p53 is directly involved in inducing apoptosis by upregulating the expression of pro-apoptotic genes such as Puma, Noxa and BAX.
As ARF loss cooperates with MYC by increasing proliferation, and BCL-XL cooperates by suppressing MYC-induced apoptosis, will the combination of ARF loss and BCL-XL expression further increase the oncogenicity of MYC? When MYC was activated, plns–Myc–ERTAM/RIP7–Bcl-xL/Arf-/- mice rapidly developed invasive tumours in which apoptosis was suppressed. Because MYC-induced apoptosis is partially suppressed in the p53-deficient background, plns–Myc–ERTAM/Trp53-/- mice also develop invasive tumours. However, the tumours remain histologically different — there is no apoptosis in the tumours of plns–Myc–ERTAM/RIP7–Bcl-xL/Arf-/- mice, but apoptosis persists in the tumours of plns–Myc–ERTAM/Trp53-/- mice.
These results increase our understanding of how these pathways synergize in mouse models, but the relative importance of suppression of apoptosis and further increased proliferation is still unclear in the evolution and protracted development of human tumours.


Nicola McCarthy
References

1. Finch, A. et al. Bcl-xL gain of function and p19ARF loss of function cooperate oncogenically with Myc in vivo by distinct mechanisms. Cancer Cell 10, 113–130 (2006) | Article | PubMed |
2. Pelengaris, S., Khan, M. & Evan, G. c-myc: more than just a matter of life and death. Nature Rev. Cancer 2, 764–776 (2002) | Article | PubMed |

[Preciouslife1]

Mechanisms of resistance to small molecule kinase inhibition in the treatment of solid tumors

ABSTRACT
A growing number of tumors are characterized by simple genetic changes that activate important biochemical pathways, which are involved in their pathogenesis. These findings have led to the concept of targeted small molecule inhibitor treatment. The prototype for this type of therapy has been treatment of chronic myelogenous leukemia with imatinib mesylate (Gleevec), which targets BCR-ABL kinase. More recently, imatinib has been used to inhibit KIT in gastrointestinal (GI) stromal tumor, a mesenchymal tumor that arises in the GI tract. Furthermore, it has been possible to target EGFR in non-small-cell lung cancer with gefitinib and erlotinib. While initial results have been encouraging, resistance to small molecule kinase inhibitors is a substantial drawback. This paper focuses on what is known about mechanisms of resistance in the treatment of solid tumors by small molecule kinase inhibitors.

Only recently, have we fully appreciated that a subset of cancers can be largely dependent on a single oncogenic pathway. This has led to the oncogene addiction hypothesis.1 In a formal test of this hypothesis, Druker et al2 proposed that inhibition of ABL-kinase might inhibit the growth of chronic myelogenous leukemia (CML), which is characterized by the BCR-ABL fusion oncoprotein in more than 90% of the cases. This strategy has been very successful as imatinib mesylate (STI-571, Gleevec/Glivec, Novartis Pharmaceuticals, Basel, Switzerland), a small molecule inhibitor of ABL kinase, has become the treatment of choice for BCR-ABL positive CML.3 These results have been extended to solid tumors by targeting KIT in gastrointestinal stromal tumors (GIST),4 and epidermal growth factor receptor (EGFR) in non-small-cell lung cancer (NSCLC).5 Unfortunately, while these therapies have been successful initially, it has become clear that monotherapies designed to inhibit oncogenic kinases are unable to completely eradicate these tumors due to the development of resistance. This review summarizes the current state of what is known about mechanisms of resistance to small molecule inhibitors of oncogenic kinases in solid tumors.

Background
GIST is characterized by the presence of oncogenic KIT or platelet-derived growth factor receptor alpha (PDGFRA) mutations.6 KIT and PDGFRA are receptor tyrosine kinases with important roles in development, proliferation and cell death of many normal cell types, including interstitial cells of Cajal, the putative precursors to GIST. Mutations cluster within several exons of KIT (exons 9, 11, 13, and 17) and PDGFRA (exons 12, 14, and 18), preserve the open reading frame and result in ligand independent, constitutive activation of the kinase. These mutations are found within sporadic GISTs and also in rare familial GIST patients.6 Furthermore, mice harboring corresponding mutations in their germ line develop GISTs.8, 9 Imatinib mesylate, also potently inhibits KIT and PDGFRA, which led to its rapid FDA approval for treatment of ********************static GISTs after having shown considerable promise in clinical trials.
Approximately, 10% of NSCLCs are characterized by mutations in EGFR (epidermal growth factor receptor), a receptor tyrosine kinase with important roles in normal and malignant cell growth.5 Within this group, non-smoking women of East Asian background with adenocarcinoma are overrepresented.10 Mutations cluster within the ATP binding pocket in exons 18-21 of EGFR. As with GIST, these mutations preserve the open reading frame and encode constitutively active kinases. NSCLCs harboring these mutations are sensitive to the EGFR inhibitors gefitinib (Iressa, AstraZeneca, Wilmington, DE, USA) and erlotinib (Tarceva, OSI Pharmaceuticals, Melville, NY, USA).11

[Preciouslife1]

Continued from post# 33 above...


Primary resistance
Primary resistance refers to patients who either do not achieve stable disease or who progress within 6 months after an initial clinical response. In GIST, primary resistance to imatinib is seen predominantly in tumors with a KIT exon 9 mutation, most PDGFRA mutations, or no detectable kinase mutation (KIT and PDGFRA wild-type tumors).12, 13 At this point, the mechanism for primary resistance due to exon 9 mutations is unknown. However, there is some evidence that increasing the dose of imatinib might be able to overcome this resistance.14 In contrast to KIT mutations, primary PDGFRA mutations often affect the kinase domain, presumably leading to conformational changes that confer primary imatinib resistance.15
Similar to what is seen in GIST without KIT or PDGFRA mutations, NSCLC without EGFR mutations are also refractory to treatment with EGFR inhibitors.11 K-ras mutations are found in approximately 30% of NSCLC and these tumors do not contain EGFR mutations.16 K-ras, is known to be a downstream signaling molecule in the EGFR pathway. Tumors harboring K-ras mutations appear to be insensitive to therapy with EGFR inhibitors.16

Secondary resistance
Secondary resistance to small molecule inhibition typically occurs after prolonged treatment, and several molecular mechanisms have been suggested to contribute to the resistance phenotype. However, only a few have been experimentally proven. The most common mechanism leads to structural alterations in the kinase domain of the originally affected kinase. This results in the inability of the inhibitor to bind to and inhibit the catalytic activity of the kinase. The primary kinase mutation is always maintained.
Secondary mutations in the kinase domain of KIT or EGFR arise in approximately 50% of patients with GIST or NSCLC that have acquired clinical resistance to imatinib or gefitinib/erlotinib therapy, respectively.12, 17, 18, 19, 20, 21, 22, 23, 24
Different regions of the kinase domain are affected by secondary mutations, and much of what has been described in imatinib-resistant CML also applies to GIST and NSCLC. A common mutation affects the so-called gatekeeper residue of the BCR-ABL fusion kinase, which is conserved in KIT and EGFR and is also found to be mutated in GIST and NSCLC, respectively (see Figure 1).25 The gatekeeper residue consists of a threonine outside the actual catalytic core of the kinase. It is important for high-affinity binding to the inhibitor with which it forms a critical hydrogen bond. Most mutations at this site are predicted to abolish the ability to form this hydrogen bond. Additionally, a larger amino-acid side chain is introduced, leading to sterical hindrance.25 Threonine to methionine mutations of the gatekeeper residue of EGFR (T790M) were seen in all but one NSCLC that developed resistance to gefitinib to date.22, 23, 24 In GIST, the gatekeeper residue is mutated in about 20% of cases with a known resistance mutation and typically leads to substitutions of the original threonine by isoleucine (T670I) or phenylalanine (T670F).12, 17, 20, 21 This codon is located in a region (exon 14) where no primary KIT mutations have been found so far.
Figure 1
(a) Diagrammatic representation of oncogenically activated receptor tyrosine kinase, (b) inhibition of oncogenically activated kinase by small molecule inhibitor (KI), (c) resistance to small molecule inhibition secondary to a mutation that disrupts a critical hydrogen bond between the kinase inhibitor and the receptor tyrosine kinase and has a bulky side chain that interferes with binding ('gatekeeper mutation').full size figure (310k)download PowerPoint slide (865k)

[Preciouslife1]

Contininued from Post#34 above..

The most common secondary mutations in GISTs are found in KIT exons 13 and 17, both with a frequency of approximately 40%.12, 18, 19, 20, 21 These regions correspond to the ATP-binding and phosphotransferase domains, also referred to as p-loop and activation loop. Similar mutations have been detected in CML patients, but are less common. These mutations presumably destabilize the closed (or inactive) conformation of the kinase and remove hydrophobic contacts.25, 26 As imatinib preferentially binds the inactive conformation of KIT, this is a potential 'Achilles' heel' that the cancers have exploited to develop resistance.25 While the p-loop mutation in GIST is always a valine to alanine substitution at residue 654 (V654A), which is never seen in primary GIST, exon 17 mutations are variable. They cluster around codon 820 (816-823) and have been found in primary GISTs. Of note, a mutation involving KIT codon 816 (D816V) is also known to be associated with mast cell neoplasms and is resistant to imatinib inhibition.27
No secondary PDGFRA mutations have been described to date in GISTs that present with a primary PDGFRA mutation. The reason for this might lie in the fact that these mutations are less common and that PDGFRA mutations more frequently show primary resistance to imatinib.
Another mechanism that can also contribute to the development of resistance is generically known as 'kinase switch'.28 This mechanism, in which tumor cells activate a different kinase than the primary, targeted kinase, has been seen in GIST. Cases have been described that presented with a primary mutation in KIT exon 11 and acquired a secondary mutation in the kinase domain of PDGFRA,12, 28 a mutation that is also found in primary imatinib-resistant GISTs.7, 15 It is therefore likely that other, yet to be determined kinases including downstream effectors could also be activated in a similar manner in tumors targeted by kinase inhibitors.
Gene amplifications of BCR-ABL have been shown to contribute to secondary resistance in CML25 and were recently described for KIT and PDGFRA in GISTs.12, 28 These presumably lead to higher expression levels, resulting in the need for higher doses of inhibitor to sufficiently inhibit the target. The situation is not as clear in NSCLC where EGFR gene amplifications can already be detected in tumors before onset of treatment.29
EGFR receptor internalization, however, has been experimentally shown to play a role in secondary resistance in NSCLC.24 Drug-resistant cells showed altered receptor trafficking and demonstrated continued dependence on EGFR signaling without containing secondary EGFR mutations.
Additional mechanisms that can at least contribute to the resistant phenotype have been proposed, but most of them still need to be better defined. These include extracellular sequestration of the drug by plasma proteins as well as an enhanced active efflux by transmembrane pump proteins such as multidrug resistance (MDR)/p-glycoprotein.25, 30

Strategies to overcome resistance
A number of strategies to overcome secondary drug resistance are currently being tested (summarized in Table 1). They can be divided into a search for compounds that target oncogenically activated kinases or drugs that inhibit downstream effectors. Interference with the activity of the oncogenic kinase can be accomplished through (i) more specific kinase inhibitors, (ii) multitargeted kinase inhibitors, (iii) compounds that act differently from classical ATP-competitive binding, and (iv) compounds that reduce kinase expression or protein levels.
Table 1
Known mechanisms of resistance to kinase inhibitionfull size table
New kinase inhibitors have been developed that have an increased specificity for their target and the ability to inhibit kinases with resistance mutations. The rationale to design these more effective inhibitors is clear, especially in the case of imatinib. Compounds that bind to the oncogenic kinase in its active state (in contrast to imatinib) would be envisioned to be more efficient in target inhibition. New ABL-specific inhibitors have been developed that are 30- to 300-times more potent than imatinib and that bind to ABL in its active conformation.25, 31 Some of these compounds also inhibit KIT and PDGFRA and have entered clinical trials for GIST.32, 33

[Preciouslife1]

Continued from Post#35 above...

A number of compounds are being developed that intentionally inhibit a broader spectrum of kinases (multitargeted inhibitors). The underlying principle is to reduce the formation of resistant cell clones by inhibiting two unrelated oncogenic mechanisms. For example, simultaneously targeting the desired oncogenic kinase plus vascular endothelial growth factor (VEGF) and PDGF receptors to inhibit the formation of new blood vessels is thought to increase the antitumor effects. Sunitinib malate (Sutent, SU11248, Pfizer, NY, USA), a multitargeted inhibitor that effectively blocks KIT, PDGF and VEGF receptors, RET and FLT3, was recently FDA-approved for the treatment of imatinib-resistant GIST (and ********************static renal cell carcinoma). It has also entered a phase II clinical trial for patients with advanced NSCLC.31, 34
Several new compounds aim at inhibiting kinases by means other than competitively binding to the ATP-binding region. EGFR inhibitors that irreversibly bind to the receptor seem to be especially useful in NSCLC. A few compounds of this class have been shown to successfully inhibit the T790M resistance mutation, and some are in clinical trials.22, 24, 35 A new group of allosteric inhibitors that impede the kinase by binding distantly to the active site have recently gained interest.36 They putatively bind to the myristoyl pocket, exhibit exceptional target specificity and have synergistic antiproliferative effects when combined with imatinib.
A last group of compounds, characterized by heat shock protein (HSP) 90 inhibitors, does not target the phosphorylation mechanism of oncogenic kinases. HSPs are molecular chaperones that guide the normal folding, intracellular disposition and proteolytic turnover of many proteins.37 Oncogenic mutations often lead to conformationally unstable proteins that need excessive amounts of chaperones to be stabilized. Consequently, inhibition of these chaperones should lead to increased proteasomal degradation of these mutant proteins.37 HSP90 inhibitors have shown promising results in preclinical studies with GIST and NSCLC, and clinical trials have been initiated.38, 39
A growing group of compounds that might help to overcome secondary resistance aims at the inhibition of signaling molecules downstream of oncogenically activated kinases. Important effectors of most tyrosine kinases are the PI3K/AKT/mTOR and RAS/RAF/MAPK pathways, respectively.31, 40 Examples in this category are inhibitors that target mTOR and are currently being tested in clinical trials for GIST.41 Moreover, inhibitors of PI3K and RAS are currently under investigation in gefitinib-resistant NSCLC.42, 43
Finally, there are several possibilities of combination therapies that have in part found their way into clinical trials. These include regimens of the original compound plus conventional radio- or chemotherapy as well as treatments with the original drug plus the addition of one of the new compounds described above.

Summary
We have now entered the era of targeted therapy with small molecule inhibition of solid tumors. While primary resistance and secondary resistance will continue to be a problem, what we have learned so far has paved the way for further advances in this exciting area. The future looks bright for the treatment of solid tumors.

[Preciouslife1]

http://yahoo.reuters.com/news/articlehybrid.aspx?storyID=urn:newsml:reuters.com: 20060924:MTFH72416_2...

Schwarz Pharma Says in Sale Talks With UCB

FRANKFURT, Sept 24 (Reuters) - Germany's Schwarz Pharma AG (SRZG.DE) is in talks to be taken over by Belgian drugmaker UCB SA (UCBBt.BR), Schwarz Pharma said late on Sunday.

"Schwarz Pharma AG is in negotiations with UCB S.A., Brussels, concerning a business combination of both companies by an offer to all shareholders of Schwarz Pharma AG," it said in a statement. "A finalisation of these talks is expected in the near-term."

A source familiar with the situation told Reuters late on Friday the Schwarz-Schuette family that controls Schwarz Pharma had started a process to sell its stake of around 60 percent in the company. The source said talks were started some weeks ago. A second source said a decision on a possible sale was nearing.

The Schwarz-Schuette family expect a price of around 4 billion euros ($5.1 billion), the first source said.

If a sale is completed, it will be the third major transaction involving a German drugmaker in four days. [*Four* recent transactions involving German drug companies if you count the takeover of Schering AG by Bayer.] On Thursday, Merck KGaA (MRCG.DE) unveiled a surprise $13.3 billion bid for Swiss biotech company Serono SA (SEO.VX) and another German group, Altana AG (ALTG.DE), said it agreed to sell its drugs unit to unlisted Danish company Nycomed for around 4.5 billion euros.

Squeezed by the spiralling cost of developing new drugs and the financial muscle of industry giants such as Pfizer Inc. (PFE) and GlaxoSmithKline Plc (GSK), smaller players are having to bulk up or sell out.

Industry analysts say the fact that medium-size European drug companies such as Merck, Altana and Serono have been controlled by families has made them slow to change. Now they are finding that the middle ground in the drugs business is shrinking as big pharmaceutical companies at one end of spectrum cosy up to small biotech firms at the other end. UCB moved early in the consolidation game, buying British biotech company Celltech in 2004.

Schwarz Pharma has been making the transition from a generic drugmaker to one that develops its own drugs and analysts like the company for its pipeline, which features neurology drugs. The company rose to prominence in 2003 as the only seller in the U.S. market of a generic version of AstraZeneca Plc's (AZN) Prilosec anti-ulcerant. It raked in windfall profits from the product, but was forced to start developing new drugs when rival generic drugmakers unexpectedly launched their versions of Prilosec, eating into its market share.

[Preciouslife1]

World-wide Warning Of Highly Drug-resistant Tuberculosis

New forms of highly drug-resistant tuberculosis are emerging and action must be taken soon before they become widespread globally, says an editorial in this week's BMJ.

The authors say that urgent action is needed to implement effective tuberculosis control strategies, especially in countries where tuberculosis control practices have been inadequate.
Research is also needed to assess the extent of the spread of these highly drug resistant strains of tuberculosis worldwide and improved means of diagnosis of tuberculosis and early detection of drug resistance are urgently required, they add.
Among 536 cases of tuberculosis confirmed at a rural hospital in South Africa earlier this year, 41% were multi-drug resistant and of those, 24% met the exact definition of being extensively drug resistant tuberculosis (also referred to as XDR tuberculosis). Such tuberculosis is almost untreatable.
All patients in this outbreak who were tested were HIV positive and 52 of the 53 died after an average of 25 days.
Strains of extensively drug resistant tuberculosis have also been noted in Europe, Asia and North and South America. It appears that there are several strains of this tuberculosis.
Author Dr Stephen Lawn, senior lecturer in infectious and tropical diseases at the University of Cape Town, South Africa, says that drug resistance to tuberculosis results largely from poorly managed and control of the disease.
Poor prescribing practices, low drug quality (or erratic supply) and poor adherence to drugs can all contribute to this resistance to drugs. Where HIV rates are high, this allows particularly rapid spread of the disease within hospital settings and the community.
Dr Lawn says several responses to this problem are required including urgent assessment of the scale of the problem and an increase in laboratory capacity.
"Detection rates for cases of tuberculosis need to be improved, highlighting the need for a new diagnostic test," he writes. "Technologies that can determine the presence of drug-resistance at the point of care are needed as are new drug treatments.

[Preciouslife1]

Apoptosis: Death by granzyme B

Olive Leavy

The death of effector T cells following activation is an important process in the termination of an immune response. However, the mechanisms that are involved in this activation-induced cell death (AICD) through engagement of the T-cell receptor (TCR) are not well understood. Now, new research published in Immunity shows that granzyme B has an important role in AICD of T helper 2 (TH2) cells.
Examination of the kinetics of AICD, by staining for annexin V and assessing membrane permeability to propidium iodide, showed that the death of TH1 cells occurred more rapidly than that of TH2 cells following TCR engagement. This finding indicates that AICD is likely to involve different mechanisms in these two cell populations. Therefore, the authors examined the role of several pro-apoptotic ligands and effector molecules in AICD of TH1 cells and TH2 cells. Blocking the pro-apoptotic molecule CD95 ligand (also known as FAS ligand) with specific agents inhibited AICD of TH1 cells, as previously reported. However, these agents had no effect on the death of TH2 cells. Similarly, blocking the activity of several caspases affected only TH1-cell death, whereas inhibition of TRAIL (tumour-necrosis-factor-related apoptosis-inducing ligand) did not affect either cell type. Therefore, none of the classic pro-apoptotic pathways seems to be involved in the death of TH2 cells.
Granzyme B is a serine protease that is an important mediator of target-cell apoptosis by cells such as natural killer cells and cytotoxic CD8+ T cells. However, granzyme B has also been shown to exert its function on certain cells that produce it, indicating that it might be involved in AICD. Interestingly, Devadas and colleagues showed that inhibition of granzyme B blocked AICD of TH2 cells but not TH1 cells. Cells that were isolated from granzyme-B-deficient mice and cultured in TH2-cell-polarizing conditions before activation showed a similar resistance to AICD.
So why are TH2 cells, but not TH1 cells, sensitive to granzyme-B-mediated AICD? Using northern-blotting analysis and real-time PCR, the authors determined that resting and activated TH1 cells and activated TH2 cells express large amounts of this protease, indicating that the sensitivity of TH2 cells to granzyme-B-mediated apoptosis is not due to preferential expression of granzyme B. The authors then examined the release of granzyme B by degranulation. Colocalization of granzyme B with lysosomal-associated membrane protein 1 (LAMP1; a marker of granules) was observed in both resting TH1 cells and resting TH2 cells. However, following TCR engagement, colocalization was observed only in TH1 cells, indicating that granzyme B is released from the granules on activation of TH2 cells but not TH1 cells. Interestingly, the amount of SPI6, which is a protease inhibitor that specifically inhibits the activity of granzyme B, was found to be increased in activated TH1 cells but not activated TH2 cells. Therefore, in contrast to TH2 cells, TH1 cells do not release granzyme B from their granules, and they express a protein that might protect them from granzyme-B-mediated AICD.
Following restimulation in vitro, CD4+ T cells from granzyme-B-deficient mice that had been immunized with ovalbumin formulated in alum produced large amounts of the TH2 cytokines interleukin-4 (IL-4), IL-5 and IL-13, but interferon- was undetectable. In a mouse model of ovalbumin-induced allergic lung inflammation, which depends on a TH2-cell response, mice deficient in granzyme B had considerably more cellular infiltrate in the lungs and more IL-4 and IL-5 in bronchoalveolar-lavage fluid than did granzyme-B-sufficient (control) mice.
So the data show that granzyme B is crucial for AICD of TH2 cells but not TH1 cells and might therefore have a role in regulating TH2-cell responses in vivo.

References and links

ORIGINAL RESEARCH PAPER

1. Devadas, S. et al. Granzyme B is critical for T cell receptor-induced cell death of type 2 helper T cells. Immunity 25, 237–247 (2006

[Preciouslife1]

Autoimmunity: Human SLE B cells lack self-control

Kirsty Minton

The autoimmune disease systemic lupus erythematosus (SLE) is characterized by the inappropriate activation and proliferation of autoreactive memory B cells in the periphery. Mouse models of SLE have shown a clear association between disease susceptibility and the amount of expression of the inhibitory IgG receptor FcRIIb. Crosslinking of FcRIIb and the B-cell receptor (BCR) — with IgG, for example — would normally inhibit BCR signalling, so it has been proposed that SLE can occur when B cells lack this self-control mechanism. However, human studies have been less conclusive, owing to a lack of specific serological reagents. Also, the role of FcRIIb polymorphisms in the susceptibility of humans to SLE varies depending on the ethnicity of the population being studied.
This study used the recently developed monoclonal antibody 2B6, which can distinguish between FcRIIa and FcRIIb, to quantify the amount of FcRIIb expressed at the surface of B cells from patients with SLE compared with those from non-autoimmune control individuals. Naive B cells from both control and disease populations expressed similar amounts of FcRIIb. But, whereas memory B cells from control individuals upregulated expression of FcRIIb, memory B cells from patients with SLE failed to do so. This failure of memory B cells to upregulate expression of FcRIIb resulted in an inability to suppress the BCR-induced Ca2+ response, which activates B cells, when cells were stimulated with IgG. Therefore, decreased FcRIIb expression by the memory B cells of patients with SLE could result in increased BCR-mediated B-cell activation.
In terms of clinical correlates, the authors could not show an association between the amount of FcRIIb expressed by memory B cells and the disease course or severity. However, there was a statistically significant association between race and the amount of FcRIIb expressed by memory B cells of patients with SLE; 55% of African-American patients showed downregulated FcRIIb expression by memory B cells, in contrast to 27% of other patients. This finding indicates that failure to upregulate FcRIIb might be the result of a genetic difference. Further work is required, however, to determine whether the decreased expression of FcRIIb by memory B cells in this study is a result of one of the previously described polymorphisms of the transmembrane-encoding or promoter regions of the gene that encodes FcRIIb in humans.

References and links

ORIGINAL RESEARCH PAPER

1. Mackay, M. et al. Selective dysregulation of the FcIIB receptor on memory B cells in SLE. J. Exp. Med. 21 Aug 2006 (doi:10.1084/jem.20051503)
   • Article

[Preciouslife1]

T-cell signalling: Aiding and abetting

Sharon Ahmad

A new paper from the laboratory of Michael Lenardo reports that the movement of caspase-8 to lipid rafts following T-cell receptor (TCR) stimulation is facilitated by tumour-necrosis-factor-receptor-associated factor 6 (TRAF6).
TCR stimulation initiates a complex signalling pathway that is not yet fully understood but culminates in the activation of transcription factors, including nuclear factor-B (NF-B). Recent reports indicate that caspase-8, better known for its role in apoptosis, also has an important role in TCR-induced NF-B activation. In response to these reports, Lenardo and colleagues studied caspase-8 and TRAF6 (a signal-transduction mediator that is known to activate transcription factors such as NF-B) during TCR stimulation.
The authors found a direct interaction between caspase-8 and TRAF6 following TCR stimulation. Two putative TRAF6-binding sites were identified in the sequence of caspase-8, and after mutating specific residues in these sites, the authors found that TRAF6 was unable to bind caspase-8, resulting in reduced TCR-induced NF-B activation.
An essential step in TCR-mediated signal transduction is the enrichment of crucial molecules in plasma-membrane compartments known as lipid rafts. These molecules include caspase-8, TRAF6, protein kinase C- (PKC), caspase-recruitment domain membrane-associated guanylate kinase protein 1 (CARMA1) and B-cell lymphoma 10 (BCL-10). 'Knockdown' experiments indicated that caspase-8 first forms a complex with BCL-10 in a PKC-dependent manner in the cytosol, leading to transient activation of caspase-8. Subsequently, TRAF6 and CARMA1 participate in the shuttling of activated caspase-8 to lipid rafts, where (as part of a larger signalosome) caspase-8 propagates NF-B signalling.

the association of activated caspase-8 with TRAF6 is crucial for TCR-induced activation of NF-B

These data indicate that the association of activated caspase-8 with TRAF6 is crucial for the translocation of caspase-8 to lipid rafts and for the subsequent TCR-induced activation of NF-B. Further questions remain, such as why transient activation of caspase-8 is required for this process, but these results help to shed light on the complex molecular pathways that are involved in mounting a successful immune response.

References and links

ORIGINAL RESEARCH PAPER

1. Bidère, N. Snow, A. L. Sakai, K. & Zheng, L. & Lenardo, M. J. et al. Caspase-8 regulation by direct interaction with TRAF6 in T cell receptor-induced NF-B activation. Curr. Biol. 16, 1666–1671 (2006)

[Preciouslife1]

Study Shows How Herpes Infects Cornea, Evades Immune Cells

Herpes virus has an unusual strategy for infecting cornea cells that may also explain how it evades the immune system, according to a study by researchers at the University of Illinois at Chicago College of Medicine.
The study appears in the Sept. 25 issue of the Journal of Cell Biology.
Both strains of the herpes virus -- HSV-1, the strain that causes cold sores on the mouth, and HSV-2, genital herpes -- can infect the cornea, the clear, domed surface that forms the eye's outermost layer. Ocular herpes is the leading cause of infectious blindness in the United States, with 50,000 new or recurring cases each year.
In about one quarter of cases, the virus penetrates the first layer of the cornea to infect an inner layer, the stroma, making the disease much more difficult to treat.
Effective treatment is hampered by poor understanding of how the virus infects the stroma, says Deepak Shukla, assistant professor of ophthalmology and visual science and microbiology and immunology, and senior author of the paper. In their study, he and his coworkers determined that the HSV-1 virus enters stroma cells in a process similar to the way bacteria, viruses and other foreign invaders are engulfed by immune cells called phagocytes.
"In the electron microscope pictures, it looks like the stroma cells form long arms that reach out and collect the virus particles, and then wrap around them, forming a sac, and bring them into the cell body," Shukla said.
In phagocytes, ingested foreign particles are destroyed in the sacs, which are highly acidic. But even though the sacs formed by the stroma cells were similar to the phagocyte's sacs, Shukla said, the envelope containing the herpes virus genome emerges from the sac undamaged and able to infect the cell. "This raises the interesting possibility that herpes may be able to evade the immune system defenses in the same way," he said.
"Understanding herpes' unusual pathway for infecting the stroma cells opens up new strategies for developing therapies against this potentially blinding disease and has implications for understanding other herpes virus infections," Shukla said.

Christian Clement and Vaibhav Tiwari are co-first authors of the paper. Perry Scanlan, Beatrice Yue and Tibor Valyi Nagy also contributed to the study.
The study was supported by grants from the National Institutes of Health, a Career Development Award from Research to Prevent Blindness Inc. to Shukla and an American Heart Association postdoctoral fellowship to Tiwari.
UIC ranks among the nation's top 50 universities in federal research funding and is Chicago's largest university with 25,000 students, 12,000 faculty and staff, 15 colleges and the state's major public medical center. A hallmark of the campus is the Great Cities Commitment, through which UIC faculty, students and staff engage with community, corporate, foundation and government partners in hundreds of programs to improve the quality of life in metropolitan areas around the world.

[Preciouslife1]

More allergic reactions from Bayer drug Trasylol.

http://heart.healthcentersonline.com/newsstories/moreallergicreactionsfrombayerdrug.cfm?general=NL_ H...

Sep 21 (Reuters) - A higher rate of allergic reactions and deaths were reported with Bayer AG's heart-surgery drug Trasylol in 2005, U.S. Food and Drug Administration staff reviewers said in a report released on Wednesday.
The FDA staff said they had "special concerns" about the 10 fatal allergic reactions reported in 2005 and would ask an advisory panel that meets Thursday to provide its perspective and suggestions for ways to lower the risk.

The panel of outside advisers also will be asked about studies that showed Trasylol raised risks of heart attacks, stroke and kidney problems in patients undergoing heart bypass surgery, the staff summary said.

In February, the FDA urged doctors to limit Trasylol use while the agency reviewed the research.

The agency staff said they would seek input on "potential product label alterations, or other options to address safety and/or efficacy concerns" about Trasylol, which is given by injection to prevent blood loss during cardiac bypass surgery.

Bayer, in a separate statement, said Trasylol was an important tool for reducing the need for blood transfusions and that clinical trials and 10 years of post-approval use "supports a favorable benefit-risk profile."

Both the FDA staff and Bayer statements were posted on the agency Web site at http://www.fda.gov/ohrms/dockets/ac/06/briefing/2006-4234B-index.htm .

Seems that bayer has been having drug problems since Baycol,
and the adverse statin drug reactions that caused the deaths
of over 100 and Rhabdomyolysis in many that took that Statin drug.....Bayer, more then an aspirin company???

[Preciouslife1]

New drug may repair heart attack and stroke damage...



(HealthCentersOnline) - By quickly rallying cells in the body that are capable of creating new blood vessels, scientists hope they can more quickly heal damage caused by a heart attack or stroke.
A heart attack is scarring, or death, of heart muscle due to lack of oxygen. A stroke is a potentially fatal event in which oxygen-rich blood flow to the brain is restricted, causing damage. Both of these conditions are often the result of an obstruction in a blood vessel.
Scientists have known about the potentially therapeutic effects of angiogenic cells for some time. These cells, which reside in the bone marrow, circulate through the blood after an injury and home in on damaged tissue. These cells are capable of accelerating the healing process by stimulating the surrounding area to grow new blood vessels that supply oxygen and nutrients to the damaged site.
Unfortunately, the angiogenic cells may take days to find injuries to help patients that have suffered heart attack or stroke damage. However, a study of a new drug may have found a way to accelerate this process, allowing angiogenic cells to rapidly mobilize and treat damaged areas.
The study showed that patients treated with the drug AMD3100 had a 10- to 20-fold increase in angiogenic cells found in the blood less than four hours after the drug was administered. By quickly entering the bloodstream in large numbers, the cells were better able to rapidly find and treat injured areas.
The study was conducted by the Washington University School of Medicine in St. Louis.
AMD3100 is not the first drug to work in this way. An already developed drug, G-CSF, works in a similar manner, but not quickly enough to improve patients' recovery rate. G-CSF takes days to work, instead of hours.
"Like AMD3100, G-CSF can bring these beneficial cells from the bone marrow into the bloodstream, but with G-CSF you don't see an increase in angiogenic cells until the fourth day," explained senior author Dr. Daniel C. Link, associate professor of medicine in the Division of Oncology, in a recent press release. "In a patient who has had a heart attack, that may be too late. In fact, two clinical trials of G-SCF found the treatment doesn't improve recovery from heart attacks." The results of the report were published in a recent issue of the journal Blood.
More on AMD3100 on this Google link:

http://www.google.com/search?hl=en&q=AMD3100&btnG=Google+Search

[Preciouslife1]

Test Helps Identify Patients With Breast Cancer Who Will Likely Benefit From Chemotherapy..

A test that measures the amounts of two members of the same protein family - one of which appears to act as an oncogene, and the other as a tumor suppressor - helps identify patients with breast cancer who will likely benefit from chemotherapy and those who won't, according to researchers.

The test, known as OncoPlan™, is already commercially available, and studies have shown that it can predict the aggressiveness of the patient's tumor and the relative risk of disease recurrence following surgery in breast, colon and gastric cancers. Now, researchers in the U.S. and Canada have studied whether it also can help identify breast cancer patients who would benefit most from chemotherapy.

Results were presented at the first meeting on Molecular Diagnostics in Cancer Therapeutic Development, organized by the American Association for Cancer Research.

OncoPlan measures two forms of Shc protein, which are known to drive the formation of protein complexes involved in signal transduction pathways and have been found to be involved in many of the pathways important to development of aggressive cancer. These two forms have a “push pull” relationship with each other: tyrosine-phosphorylated (PY)-Shc helps drive these dangerous cell pathways, but p66 Shc, after initial stimulation, works to inhibit the very growth pathway the other Shc proteins promote.

“This may be one mechanism whereby normal cells prevent runaway growth,” said the study's lead author, A. Raymond Frackelton, Jr., Ph.D., a Brown University associate professor, staff scientist at Roger Williams Medical Center and Vice President of Research at Catalyst Oncology, which is marketing OncoPlan. “Perhaps more importantly, aggressive cancer cells must endure oxidative stress-stress that in normal cells triggers p66 Shc to cause cellular suicide,” he said. “Tumor cells, then, may have both growth and survival advantages if p66 Shc levels are low.”

Chemotherapy-mediated killing of tumor cells, however, does not require p66 Shc, Frackelton said, suggesting that patients whose tumor cells have low p66 Shc might respond well to chemotherapy. To test this idea, the researchers looked at the Shc proteins in tumors from 2,380 women from British Columbia who were diagnosed with invasive breast cancer, 717 of whom received chemotherapy as part of their initial treatment.

They found that, indeed, patients who had low levels of p66 Shc and did not receive chemotherapy had very poor outcomes. If similar patients received chemotherapy, however, their chances of relapsing and dying from their disease were reduced by two-fold or more, said Frackelton. Conversely, women with high levels of p66 Shc had a much higher likelihood of surviving their disease, but appeared to derive no benefit from chemotherapy, he said.

Possible additional associations between PY-Shc and chemotherapy benefit has not yet been fully explored, Frackelton said. “But even at this point, the results are very exciting because, with further validation in clinical trials, OncoPlan, which is already being used to predict disease aggressiveness, will help to ensure that individual patients receive the most beneficial therapies,” he said.

The mission of the American Association for Cancer Research is to prevent and cure cancer. Founded in 1907, AACR is the world's oldest and largest professional organization dedicated to advancing cancer research. The membership includes more than 24,000 basic, translational, and clinical researchers; health care professionals; and cancer survivors and advocates in the United States and more than 60 other countries. AACR marshals the full spectrum of expertise from the cancer community to accelerate progress in the prevention, diagnosis and treatment of cancer through high-quality scientific and educational programs. It funds innovative, meritorious research grants. The AACR Annual Meeting attracts more than 17,000 participants who share the latest discoveries and developments in the field. Special Conferences throughout the year present novel data across a wide variety of topics in cancer research, treatment, and patient care. AACR publishes five major peer-reviewed journals: Cancer Research; Clinical Cancer Research; Molecular Cancer Therapeutics; Molecular Cancer Research; and Cancer Epidemiology, Biomarkers & Prevention. Its most recent publication, CR, is a magazine for cancer survivors, patient advocates, their families, physicians, and scientists. It provides a forum for sharing essential, evidence-based information and perspectives on progress in cancer research, survivorship, and advocacy.

American Association for Cancer Research (AACR)