HDAC1 and HDAC6 are essential for driving growth in IDH1 mutant glioma

Low-grade and secondary high-grade gliomas frequently contain mutations in the IDH1 or IDH2 metabolic enzymes that are hypothesized to drive tumorigenesis by inhibiting many of the chromatin-regulating enzymes that regulate DNA structure. Histone deacetylase inhibitors are promising anti-cancer agents and have already been used in clinical trials. However, a clear understanding of their mechanism or gene targets is lacking. In this study, the authors genetically dissect patient-derived IDH1 mutant cultures to determine which HDAC enzymes drive growth in IDH1 mutant gliomas. A panel of patient-derived gliomasphere cell lines (2 IDH1 mutant lines, 3 IDH1 wildtype lines) were subjected to a drug-screen of epigenetic modifying drugs from different epigenetic classes. The effect of LBH (panobinostat) on gene expression and chromatin structure was tested on patient-derived IDH1 mutant lines. The role of each of the highly expressed HDAC enzymes was molecularly dissected using lentiviral RNA interference knock-down vectors and a patient-derived IDH1 mutant in vitro model of glioblastoma (HK252). These results were then confirmed in an in vivo xenotransplant model (BT-142). The IDH1 mutation leads to gene down-regulation, DNA hypermethylation, increased DNA accessibility and H3K27 hypo-acetylation in two distinct IDH1 mutant over-expression models. The drug screen identified histone deacetylase inhibitors (HDACi) and panobinostat (LBH) more specifically as the most selective compounds to inhibit growth in IDH1 mutant glioma lines. Of the eleven annotated HDAC enzymes (HDAC1-11) only six are expressed in IDH1 mutant glioma tissue samples and patient-derived gliomasphere lines (HDAC1-4, HDAC6, and HDAC9). Lentiviral knock-down experiments revealed that HDAC1 and HDAC6 are the most consistently essential for growth both in vitro and in vivo and target very different gene modules. Knock-down of HDAC1 or HDAC6 in vivo led to a more circumscribed less invasive tumor. The gene dysregulation induced by the IDH1 mutation is wide-spread and only partially reversible by direct IDH1 inhibition. This study identifies HDAC1 and HDAC6 as important and drug-targetable enzymes that are necessary for growth and invasiveness in IDH1 mutant gliomas.

Pathways into receiving a prescription for diamorphine (heroin) for the treatment of opiate dependence in the United kingdom

In the UK, few doctors prescribe diamorphine for the treatment of opiate dependence to a small number of patients. A retrospective case note review of patients receiving diamorphine in 2000 was conducted in the UK to determine how and why these patients came to receive a prescription for diamorphine. Patient eligibility criteria were examined together with doctors' stated reasons for initiating a diamorphine (heroin) prescription. Two hundred and ten sets of patients' case notes were reviewed at 27 of the 42 (64%) drug clinics in England and Wales where diamorphine was prescribed by the doctor. There appeared to be a general consensus among the few doctors who had prescribed diamorphine that it was a treatment of last resort, for those with long histories of heroin use and injecting, and those who had not responded sufficiently well to previous other treatments. However, there was also a small number of patients initiated on diamorphine without ever having previously received opiate treatments and some because they were experiencing problems injecting methadone. This reflects the UK history of the individual doctor's clinical autonomy in deciding when diamorphine is appropriate and the previous lack of nationally agreed patient eligibility criteria.

Patients receiving a prescription for diamorphine (heroin) in the United Kingdom

The United Kingdom is unusual internationally in that it is one of few countries able to prescribe diamorphine for the treatment of opiate dependence. Prescribing diamorphine has been part of the UK response to drug problems since the 1920s. Despite this, little is known about who receives diamorphine and how treatment is delivered. This study aims to describe the characteristics and treatment regimes of opiate-dependent drug users receiving a prescription for diamorphine in the United Kingdom in 2000, and report on their status in 2002. A retrospective case-note review was conducted in England and Wales. Two hundred and ten (72%; 210/292) patients' sets of case-notes were reviewed at 27 of the 42 (64%) drug clinics where diamorphine was prescribed by the doctor. Patients had been receiving a prescription for diamorphine for a median length of six years. The majority were unemployed white males, with a median age of 44 years. Illicit drug use and criminal activity, while low, had not been eliminated totally. The majority were prescribed ampoules and few had significant health problems. In some cases patients had been transferred to injectable diamorphine from injectable methadone to reduce injection related problems. There were wide variations in dose. The majority of patients had no serious drug, health or social problems. Diamorphine prescribing was a long-term commitment. The experience from the United Kingdom has been one of long-term prescribing with the aim of retaining patients in treatment and reducing the harms caused by illicit drug use. Prospective studies are needed to determine the long-term consequences of receiving a diamorphine prescription.

The dynamics of heroin use; implications for intervention

STUDY OBJECTIVE

To use a readily available dataset to detect periods of epidemic change and to examine the progression of heroin epidemics in different geographical areas. To consider the implications of epidemic change for strategies to tackle drug misuse.

DESIGN

Comparison of trends in new treatment demand, observed incidence, and age specific population rates for treated heroin users in two geographical areas.

PARTICIPANTS

Heroin users recorded to have sought treatment.

MAIN RESULTS

The areas studied seem to show differences with respect to trends in new treatment demand, incidence of heroin use and distribution of age specific population rates; indicating that they may be at different epidemic stages.

CONCLUSIONS

These analyses show how areas may differ with respect to epidemic progression of heroin use. It is essential that government strategies, and local responses to these, should be cognisant of these dynamics.

Zolpidem tolerance and dependence--two case reports

Two cases of zolpidem tolerance and dependence are reported. The literature is reviewed for other reported cases, and the potential for abuse of zolpidem is discussed.

Randomised double-blind comparison of lofexidine and clonidine in the out-patient treatment of opiate withdrawal

This study compares the clinical response to lofexidine and clonidine in the out-patient treatment of opiate withdrawal in 50 opiate addicts, using a randomised double-blind study design. Patients were taking 40 mg or less methadone daily, or equivalent amounts of other opiates. Fifty-eight percent of those starting treatment completed detoxification, and were opiate free at 4 weeks: more patients completed withdrawal in the lofexidine group, but the difference was not significant. Clonidine produced more hypotensive effects: more home visits were also required by medical staff. There was no other significant difference in side effects. Both drugs can be used successfully in out-patient detoxification, but lofexidine is more economical in regard to staff time.

Switching on the work force--computerizing a drug team

Shortage of medical time and an increasing number of clients led to difficulties in handling the heavy prescribing load of a community drug team. A computer program was developed to help with this. The program was soon expanded and now plays a key role in the general administration of the team, and in data collection. Its enthusiastic use by team workers not accustomed to computers suggests that similar initiatives could play an important role in future research.