Generation and optimization of off-the-shelf immunotherapeutics targeting TCR-Vβ2+ T cell malignancy

Current treatments for T cell malignancies encounter issues of disease relapse and off-target toxicity. Using T cell receptor (TCR)Vβ2 as a model, here we demonstrate the rapid generation of an off-the-shelf allogeneic chimeric antigen receptor (CAR)-T platform targeting the clone-specific TCR Vβ chain for malignant T cell killing while limiting normal cell destruction. Healthy donor T cells undergo CRISPR-induced TRAC, B2M and CIITA knockout to eliminate T cell-dependent graft-versus-host and host-versus-graft reactivity. Second generation 4-1BB/CD3zeta CAR containing high affinity humanized anti-Vβ scFv is expressed efficiently on donor T cells via both lentivirus and adeno-associated virus transduction with limited detectable pre-existing immunoreactivity. Our optimized CAR-T cells demonstrate specific and persistent killing of Vβ2+ Jurkat cells and Vβ2+ patient derived malignant T cells, in vitro and in vivo, without affecting normal T cells. In parallel, we generate humanized anti-Vβ2 antibody with enhanced antibody-dependent cellular cytotoxicity (ADCC) by Fc-engineering for NK cell ADCC therapy.

Integrated transcriptome and trajectory analysis of cutaneous T-cell lymphoma identifies putative precancer populations

The incidence of cutaneous T-cell lymphoma (CTCL) increases with age, and blood involvement portends a worse prognosis. To advance our understanding of the development of CTCL and identify potential therapeutic targets, we performed integrative analyses of paired single-cell RNA and T-cell receptor (TCR) sequencing of peripheral blood CD4+ T cells from patients with CTCL to reveal disease-unifying features. The malignant CD4+ T cells of CTCL showed highly diverse transcriptomic profiles across patients, with most displaying a mature Th2 differentiation and T-cell exhaustion phenotype. TCR-CDR3 peptide prediction analysis suggested limited diversity between CTCL samples, consistent with a role for a common antigenic stimulus. Potential of heat diffusion for affinity-based trajectory embedding transition analysis identified putative precancerous circulating populations characterized by an intermediate stage of gene expression and mutation level between the normal CD4+ T cells and malignant CTCL cells. We further revealed the therapeutic potential of targeting CD82 and JAK that endow the malignant CTCL cells with survival and proliferation advantages.

BET inhibition in advanced cutaneous T cell lymphoma is synergistically potentiated by BCL2 inhibition or HDAC inhibition

While several systemic therapies are approved for cutaneous T cell lymphoma (CTCL), a non-Hodgkin lymphoma of skin-homing T cells that may involve lymph nodes and peripheral blood in advanced stages, relapses are common. Mutational analysis of CTCL cells has revealed frequent amplification of the MYC oncogene, and bromodomain and extraterminal (BET) protein inhibitors have been shown to repress MYC expression in various malignancies. Towards a potential novel therapy, we thus sought to examine the effect of BET inhibition on CTCL cells in vitro. Each of the four tested BET inhibitors (JQ1, ABBV-075, I-BET762, CPI-0610) consistently induced dose-dependent decreases in viability of isolated patient-derived CTCL cells and established CTCL cell lines (MyLa, Sez4, HH, Hut78). This effect was synergistically potentiated by combination of BET inhibition with BCL2 inhibition (e.g. venetoclax) or histone deacetylase (HDAC) inhibition (e.g. vorinostat or romidepsin). There was also a marked increase in caspase 3/7 activation when JQ1 was combined with either vorinostat or romidepsin, confirming that the observed synergies are due in major part to induction of apoptosis. Furthermore, MYC and BCL2 expression were each synergistically repressed when CTCL cells were treated with JQ1 plus HDAC inhibitors, suggesting cooperative activities at the level of epigenetic regulation. Taken together, these data indicate that targeting BET proteins in CTCL represents a promising novel therapeutic strategy that may be substantially potentiated by combination with BCL2 or HDAC inhibition.

Cutaneous T-cell lymphoma (CTCL): Current practices in blood assessment and the utility of T-cell receptor (TCR)-Vβ chain restriction

BACKGROUND

Accurate quantification of malignant cells in the peripheral blood of patients with cutaneous T-cell lymphoma is important for early detection, prognosis, and monitoring disease burden.

OBJECTIVE

We sought to determine the spectrum of current clinical practices; critically evaluate elements of current International Society for Cutaneous Lymphomas (ISCL) B1 and B2 staging criteria; and assess the potential role of T-cell receptor-Vβ analysis by flow cytometry.

METHODS

We assessed current clinical practices by survey, and performed a retrospective analysis of 161 patients evaluated at Yale (2011-2014) to compare the sensitivity, specificity, positive predictive value, and negative predictive value of parameters for ISCL B2 staging.

RESULTS

There was heterogeneity in clinical practices among institutions. ISCL B1 criteria did not capture 5 Yale cohort cases with immunophenotypic abnormalities that later progressed. T-cell receptor-Vβ testing was more specific than polymerase chain reaction and aided diagnosis in detecting clonality, but was of limited benefit in quantification of tumor burden.

LIMITATIONS

Because of limited follow-up involving a single center, further investigation will be necessary to conclude whether our proposed diagnostic algorithm is of general clinical benefit.

CONCLUSION

We propose further study of modified B1 criteria: CD4/CD8 ratio 5 or greater, %CD4(+) CD26(-) 20% or greater, or %CD4(+) CD7(-) 20% or greater, with evidence of clonality. T-cell receptor-Vβ testing should be considered in future diagnostic and staging algorithms.

A transient epidermolysis bullosa simplex-like phenotype associated with bexarotene treatment in a G138E KRT5 heterozygote

Basal keratinocyte lysis is the hallmark histopathological finding of epidermolysis bullosa simplex (EBS), a group of rare heritable mechanobullous disorders characterized by intraepidermal blister formation and skin fragility. Over 100 mutations, found predominantly in the genes encoding keratins 5 and 14 (KRT5, KRT14), have been described to account for a variety of clinical subtypes. EBS with mottled pigmentation (EBS-MP) is a rare variant featuring childhood-onset reticulate hyperpigmentation and focal palmoplantar keratoderma, typically associated with a P25L KRT5 mutation. In this report, we present the case of a 77-year-old woman with a history of palmoplantar keratoderma who developed a transient EBS-MP-like phenotype associated with bexarotene treatment for cutaneous T-cell lymphoma. Genetic sequencing revealed a heterozygous G138E KRT5 variant, present in approximately 10% of the European population and only rarely associated with pathology. Bexarotene, which has been reported to alter keratin synthesis, caused vesiculobullous reactions with similar frequency in clinical trials. We propose that the cumulative effect of drug treatment and underlying G138E polymorphism resulted in transient basal keratinocyte lysis in our patient and provides a plausible explanation for this unusual bexarotene side effect.

FDG-PET/CT for the evaluation of response to therapy of cutaneous T-cell lymphoma to vorinostat (suberoylanilide hydroxamic acid, SAHA) in a phase II trial

INTRODUCTION

Harnessing the power of molecular imaging in particular positron emission tomography (PET) to assess response to therapy in early clinical trials has the potential to yield crucial data on efficacy and streamline drug development. Vorinostat (also known as SAHA, suberoylanilide hydroxamic acid) is a histone deacetylase (HDAC) inhibitor which alters gene transcription to inhibit proliferation and promote apoptosis.

METHODS

In a phase II trial of vorinostat for cutaneous T cell lymphoma (CTCL), 2-deoxy-2-[F-18]fluoro-D-glucose (FDG)-PET/computed tomography (CT) was performed on patients with both cutaneous and nodal disease. FDG-PET/CT fuses the power of metabolic imaging from FDG-PET with the anatomic detail of CT. Scans were conducted on subjects pre-therapy and during therapy.

RESULTS

Changes in the values of FDG uptake and measurements of nodal dimensions and thickness of cutaneous lesions were tabulated. FDG-PET/CT provided an objective measure of the response (or lack thereof) of both cutaneous and nodal disease to therapy with vorinostat. The results of this study are encouraging for the potential utility of FDG-PET/CT in future trials with HDAC inhibitors for other diseases and for CTCL with other therapies.

CONCLUSION

Further study will be required to determine the prognostic value of the initial PET/CT scan and response on follow-up scans.

Correct utilization and management of peripherally inserted central catheters and midline catheters in the alternate care setting

Based on patient condition, intravenous therapies, caregiver support, and organizational policy, correct device selection plays an integral part in the overall care and management of the alternate care setting i.v. therapy patient. This paper will identify the various aspects of appropriate device selection for i.v. therapy prescriptions.

Ethanol and cocaine intake by rats selectively bred for oral opioid acceptance

Lines which accept or reject the potent opioid etonitazene, and a randomly bred control line, were assessed for the specificity of selective breeding. Drug-naive subjects from generation 8 were offered a continuous choice between water and 10% ethanol for 20 days. There was no difference between the accepting and rejecting lines in preference for one fluid, or in amount of ethanol consumed. The same rats were then given a choice between water and increasing concentrations (0.08-0.64 mg/ml) of cocaine, 7 days at each concentration. There were no differences among the lines in preference for the drug, but the rejecting line drank more of the cocaine solution than the accepting line. Finally, these rats were subjected to the regimen used in choosing rats for selective breeding, 4 days of a water-etonitazene choice. In their preference for etonitazene the order of the lines was as expected: accepting > control > rejecting. In addition, the accepting line drank more of the etonitazene solution than the other two lines. These data suggest that selection has been rather specific and not for a generalized tendency to become intoxicated.

Selective breeding for oral opioid acceptance or rejection in rats

Lines of rats were selectively bred to diverge bidirectionally from a randomly bred control line in the propensity to self-administer an opioid orally. These lines seek or avoid the high-potency opioid etonitazene in a situation in which it is presented continuously as a choice with water. Over seven generations, preferences were measured and selection pressure imposed to develop the accepting and rejecting lines. These animals represent the only contemporary selective breeding program for opioid preference or self-administration, and hold the promise of being a useful resource in the drug-abuse field.

Etonitazene: an opioid selective for the mu receptor types

Specific radioligand binding protocols were utilized to compare the affinity of morphine and the high-potency opioid etonitazene at mu 1, mu 2, delta, kappa 1 and sigma receptors. Both etonitazene and morphine displayed a mu 1-selective binding profile; however, etonitazene had a 2500-fold higher affinity at this receptor type. The latter result is consistent with the relative potencies or morphine and etonitazene in various behavioral tests.

Augmentation of morphine-induced changes in brain monoamine metabolism after chronic naltrexone treatment

To investigate the role of opioid mechanisms in the regulation of cerebral monoaminergic neurons, male Wistar rats were continuously infused with naltrexone via an Alzet osmotic minipump, or were sham-implanted, for 14 days. Twenty-four hours after removal of the pumps or sham implants, the rats were given s.c. morphine (3, 10 or 30 mg/kg) or saline and were sacrificed 2 hr postinjection. Eight brain regions were assayed for dopamine, 5-hydroxytryptamine, noradrenaline and their respective metabolites. Chronic naltrexone treatment per se caused only small changes in cerebral monoamines. Morphine elevated dose-dependently the cerebral concentrations of the acidic dopamine metabolites, 3,4-dihydroxyphenylacetic acid and homovanillic acid, as well as that of the 5-hydroxytryptamine metabolite, 5-hydroxyindoleacetic acid, and that of the noradrenaline metabolite, free 3-methoxy-4-hydroxyphenylethyleneglycol. In naltrexone-pretreated rats these elevations were significantly larger. Furthermore, in the naltrexone-pretreated rats 10 mg/kg of morphine significantly decreased the concentration of the dopamine metabolite 3-methoxytyramine both in the striatum and in the limbic forebrain, whereas in the control rats the 3-methoxytyramine content fell first after the 30-mg/kg dose and only in the striatum. Thus, both the stimulatory and the inhibitory effects of morphine on cerebral monoaminergic neurons seem to be potentiated by chronic naltrexone treatment. These data suggest that the activity of cerebral monoaminergic systems is to some degree regulated by an endogenous opioid input. When that input is chronically blocked, the basal metabolism of monoamines is not much altered but the systems' responsiveness to agonist challenge is increased.

Taste vs. CNS effects in voluntary oral opiate intake: studies with a novel device and technique

An apparatus is described which negates the influence of rats' position preferences by presenting alternative solutions at the same location. The licks for both solutions were monitored over consecutive short intervals by lick detectors with computer capture of data. Rats given a choice between water and dilute solutions of the high-potency opiates etonitazene (1.0-5.0 micrograms/ml) or fentanyl (10-50 microgram/ml) either licked equally for the two solutions, or gradually developed a preference or aversion regarding the opiate over the course of several days. In contrast, preferential licking for solutions with a definite taste, saccharin or quinine, was established in hours. These data indicate that the taste per se of these opiates is not aversive to rats, and that preferences for or aversions to the opiates have some other base, presumably one or more actions on the central nervous system.

Changes in brain monoamine metabolism during withdrawal from chronic oral self-administration of morphine and in response to a morphine challenge in the withdrawn state

Although p.o. self-administration of morphine is a reliable and convenient means of inducing physical dependence, its effects on brain monoamine metabolism have not been determined. Accordingly, in the present experiment young Wistar rats drank increasing concentrations (0.1-0.5 mg/ml) of morphine in water, or water alone, for 37 days. Half the rats in each group were challenged with morphine (10 mg/kg s.c.) when 27 to 29 hr withdrawn, and half with saline. Rats were sacrificed 2 hr postinjection. Seven brain regions were analyzed for noradrenaline (NA), dopamine (DA), or 5-hydroxytryptamine (5-HT), and their respective metabolites. In all cases in which a comparison could be made with prior work utilizing repeated injections to produce dependence, the p.o. regimen produced the same effects. Thus, the mode of administration does not seem to modify the response of monoaminergic neurons to chronic morphine. In withdrawal, NA turnover increased but DA and 5-HT turnovers decreased. Acute morphine accelerated the turnover of all three monoamines. The NA response was attenuated in some brain regions of withdrawn rats, indicating the development of tolerance to the turnover-enhancing effect of acute morphine in noradrenergic neurons. In contrast, the effect of acute morphine on cerebral 5-HT turnover was not altered, and its effect on cerebral DA turnover was enhanced in withdrawn rats. Our results suggest that there are fundamental differences among the three monoaminergic systems in their capacities for adapting to chronic morphine treatment.

Morphine dependence and protracted abstinence: regional alterations in CNS radioligand binding

Rats (Fisher F-344) were given free access to a 10% sucrose solution containing 0.5 mg/ml morphine sulfate (controls received the sucrose vehicle only) as their sole source of fluid. Daily morphine intake averaged 119 +/- 21 mg/kg, an amount sufficient to induce physical dependence. After 18 days on this regimen, the control and dependent subjects were sacrificed. A protracted abstinence group was weaned from morphine by reducing its concentration in the vehicle by 20% over the next 5 days, followed by a 5-week drug-free period before sacrifice concurrent with the other groups. These subjects showed no signs of an abstinence syndrome. Binding assays for alpha-2 adrenergic sites (3H-clonidine), beta-1/beta-2 adrenergic sites (3H-dihydroalprenolol), and dopaminergic (D2)/serotonergic (5-HT2) sites (3H-spiroperidol) were performed on tissue from frontal cortex, hippocampus, striatum, and brainstem. No alterations in 3H-clonidine or 3H-dihydroalprenolol binding were observed in dependence or protracted abstinence, suggesting that noradrenergic systems are well-regulated both during dependence and in protracted abstinence. 3H-spiroperidol binding was significantly elevated in the striatum (D2 sites) and hippocampus (5-HT2 sites) during dependence. Hippocampal 3H-spiroperidol binding returned to control levels in protracted abstinence, reflecting a morphine-induced change in 5-HT2 binding sites which had normalized by 5 weeks post-drug. Striatal 3H-spiroperidol binding was significantly decreased below control levels after withdrawal, suggesting that alterations of D2 sites in this structure may play a role in protracted abstinence.

Comparison of regional CNS ligand binding in two inbred rat strains: effects of chronic morphine

Male rats of the F-344 and BUF inbred strains were given free access to a 10% sucrose solution containing 0.5 mg/ml morphine sulfate (controls received sucrose only) as their sole source of fluids. The daily intake of morphine averaged 101 +/- 13 mg/kg. After 18 days on this regimen, animals were sacrificed and assayed for 3H-clonidine (alpha-2 adrenergic), 3H-dihydroalprenolol (DHA, beta 1 and 2 adrenergic) and 3H-spiperone (SPD, 5-HT2 and D2) binding in several brain regions. In the absence of morphine treatment, BUF rats displayed higher levels of SPD binding in brainstem, as compared with the F-344 strain. In contrast, untreated F-344 rats exhibited higher levels of DHA binding in hypothalamus and SPD binding in striatum than BUF rats. Chronic morphine resulted in an increase in clonidine and DHA binding in the brainstem and hippocampus respectively of BUF, but not F-344 rats, suggesting a greater sensitivity of adrenergic function to opiate treatment in the BUF strain. The two strains differed qualitatively in the effect of morphine on striatal SPD binding, with BUF rats exhibiting a decrease, and F-344 rats an increase. The one consistent change observed in both strains was a quantitatively similar increase in hippocampal SPD binding after chronic morphine. The results demonstrate that despite strain-dependent differences in binding characteristics, chronic morphine elicits a strain-independent alteration in hippocampal 5-HT2 binding. On the basis of these preliminary findings, it may be speculated that this particular neurochemical consequence contributes to morphine-induced behaviors which are observed independent of rat strain.

Rapid determination of dopamine uptake in synaptosomal preparations

A rapid method for assay of dopamine uptake in synaptosomal preparations involving reisolation of radiolabeled synaptosomes by rapid centrifugation is described. Utilizing this technique it was found that dopaminergic synaptosomes are relatively short lived, thus emphasizing the importance of rapid assay following tissue preparation. The effects of d-amphetamine, nomifensine and amfonelic acid were tested using the new procedure. The results of these experiments show a relative potency of uptake inhibition by these compounds which is comparable to previously published data.

Interaction of opiates with dopamine receptors: receptor binding and behavioral assays

We examined the hypothesis that opiates act as dopamine (DA) receptor-blocking agents thereby inducing a compensatory increase in DA receptor density during chronic administration, and that increased receptor density could account for the behavioral hypersensitivity to DA agonists seen after treatment with opiates. Morphine and methadone did not inhibit the specific binding of 3H-spiroperidol to DA receptors in vitro, nor did they decrease affinity or apparent receptor density in the striatum when administered acutely in vivo in behaviorally effective doses. In contrast, neuroleptics had the expected inhibitory effect in both these experiments. Stereotypy and locomotion in response to apomorphine were measured before and after a 3-week treatment with saline or methadone. About half the methadone-treated rats showed significant increases over predrug baselines in stereotypy or locomotion, as did a few saline-treated animals. However, in those animals showing enhanced stereotypy or locomotion, DA receptor density was not elevated in striatum or mesolimbic areas respectively. These results indicate that opiates do not act as antagonists at DA receptor sites, and that changes in DA receptor density cannot account for opiate-induced behavioral hypersensitivity.

Pentobarbital induces a naloxone-reversible decrease in mesolimbic self-stimulation threshold

The effects of sodium pentobarbital and naloxone were tested on intracranial self-stimulation (ICSS) in rats implanted with electrodes in the ventral tegmental area. Threshold for ICSS was determined using a rate-independent current titration paradigm. A low dose of pentobarbital (5 mg/kg) did not have a significant effect on ICSS thresholds, while a high dose (20 mg/kg) rendered the subjects too ataxic to respond reliably in the operant task. An intermediate dose (10 mg/kg) induced a highly significant lowering of threshold (17% below saline baseline levels) without apparent deterioration in response capability. The concurrent administration of naloxone (2 mg/kg) significantly reversed the pentobarbital-induced threshold decrease, while naloxone treatment alone had no effect on the ICSS threshold.

Time course of dopaminergic hypersensitivity following chronic narcotic treatment

Guinea pigs were injected SC for 3 weeks with 3 different dosage schedules of morphine or methadone, or with saline. For 8 weeks thereafter they were challenged weekly with the dopamine agonist apomorphine. Hypersensitivity was manifested in more intense stereotypies, as compared to the saline group, by all morphine and methadone groups. Hypersensitivity persisted longer after the termination of methadone treatment (maximum of 8 weeks) than after morphine administration (maximum of 3 weeks). The degree of hypersensitivity, and its duration after treatment, was positively related to methadone dosage. In some groups a period of hyposensitivity was seen following hypersensitivity. These data are interpreted with reference to the hypothesized mechanism underlying the development of hypersensitivity, the different durations of action of morphine and methadone, and the retention of methadone in brain following treatment.

Sensitivity to apomorphine in the guinea pig as a function of age and body weight

Male albino guinea pigs aged 4--10 weeks were challenged with 0.1, 0.2, and 0.4 mg/kg apomorphine. Mean stereotypy scores rose signfiicantly as a function of age. Stereotypy scores were better correlated with age than with body weight, suggesting that CNS maturation, rather than weight-related factors, were responsible. Although age and body weight were correlated, there was enough variability to make bvody weight an unreliable indicator of age.

Behavioral supersensitivity to apomorphine following chronic narcotic treatment in the guinea pig

Male albino guinea pigs were treated for 3 weeks with methadone, morphine, haloperidol, or saline. One week and 5 weeks following termination of treatment they were challenged with the directly acting dopaminergic agonist apomorphine. At the week 1 test the haloperidol and saline groups did not differ, but behavioral supersensitivity was apparent in significantly elevated mean stereotypy scores of the methadone and morphine groups relative to the saline group. The source of differences in mean scores was a higher peak score rather than increased duration of action. At the week 5 test the scores of the methadone group were even higher, the morphine group's scores were equivalent to the saline group's, and the haloperidol group's scores were significant depressed. This study indicates that a 3-week treatment period with methadone or morphine is sufficient to induce dopaminergic supersensitivity and suggests that there may be different time courses for the retention or expression of supersensitivity following these narcotics.

Effect of chronic oral methadone treatment on the growth of maturing monkeys

Three male rhesus monkeys drank methadone hydrochloride (1.0-2.5 mg/kg/day) in Tang orange drink from age two to four years. Their rate of body weight gain was faster than that found by other experimenters. In a second study one male monkey drank 2.0 mg/kg/day methadone while two others drank only Tang from age 21/2 to 31/2 years. The rate of body weight gain was identical for the three monkeys, and was the same as that found in the previous study. The apparent augmentation of body weight gain in the first study was probably due to inter-laboratory differences in housing and feeding conditions.

Susceptibility to amphetamine-elicited dyskinesias following chronic methadone treatment in monkeys

Eight rhesus monkeys that had drunk subdependence-producing doses of methadone daily for 10-22 months, and had subsequently been drug-free for 2-17 months, were injected with low doses of methamphetamine (MA). They immediately exhibited oral dyskinesias resembling the symptoms of tardive dyskinesia in humans, a condition resulting from chronic blockade of striatal dopamine receptors by neuroleptics. Eleven control monkeys failed to develop dyskinesias during prolonged MA administration. Control monkeys then received parenteral methadone, chlorpromazine, haloperidol, or saline for 45 days. Upon subsequent retest with MA, the methadone and chlorpromazine monkeys immediately displayed oral dyskinesias. Dopaminergic antagonists blocked MA-elicited dyskinesis, whereas neither a noradrenergic blocker nor sedative doses of phenobarbital and diazepam had any effect on dyskinesias. We suggest that receptor supersensitivity is produced by chronic treatment with methadone or other dopamine receptor blockers. Following treatment, stimulation of hypersensitive striatal receptors by the dopamine released by MA results in oral dyskinesias. The clinical implications for methadone maintenance treatment program patients are discussed.

Dyskinesias in monkeys: interaction of methamphetamine with prior methadone treatment

Rhesus monkeys with a history of drinking methadone, but presently drug-free, were injected with low doses of methamphetamine (MA). They immediately developed oral dyskinesias resembling the symptoms of tardive dyskinesia in humans, a condition resulting from chronic blockade of striatal dopamine receptors by neuroleptics. Nine of 11 control monkeys failed to develop dyskinesias during prolonged MA administration. A stressful stimulus intensified the MA-elicited oral dyskinesias, an effect analogous to exacerbation of tardive dyskinesias by emotional stress. Control monkeys were then injected with methadone, chlorpromazine, haloperidol, or saline for 45 days. Ten days following this chronic treatment, MA immediately elicted oral dyskinesias in the methadone and chlorpromazine monkeys. Acute administration of the dopaminergic blocking agents chlorpromazine, spiroperidol, and clozapine eliminated MA-elicited dyskinesias, whereas the alpha-adrenergic blocker phentolamine was ineffective. Physostigmine blocked the dyskinesias in 1 of 2 cases. Sedative doses of phenobarbital and diazepam had no effect on oral dyskinesias. These data indicate that chronic treatment with methadone or other dopamine receptor blocking agents leads to receptor supersensitivity to the actions of MA.

Behavioral evidence for dopaminergic supersensitivity following chronic treatment with methadone or chlorpromazine in the guinea pig

This study demonstrated the enhancement, as a consequence of prior chronic drug treatment, of two behaviors (stereotyped oral behaviors and open field locomoation) which are thought to depend primarily on the striatel dopamine system. Following a 5-week treatment with methadone (MD), chlorpromazine (CPZ), or saline, the dopamine agonist methamphetamine (MA) elicited more intense stereotypies in the MD and CPZ animals. After chronic treatment with MD, the MA-elicited stereotypies were reduced by an acute dose of MD. Stereotyped oral behaviors elicited by a stressful stimulus (foot shock) were enhanced in the MD animals both during and following chronic drug treatment. MA-elicited open field locomotion, measured 2 weeks following termination of chronic drug treatment, was enhanced in the MD and CPZ animals.

Dyskinesias elicited by methamphetamine: susceptibility of former methadone-consuming monkeys

Rhesus monkeys with a history of drinking methadone but currently drug-free and control monkeys with no drug history were injected with methamphetamine hydrochloride (2 to 5 milligrams per kilogram of body weight). In six of seven monkeys which had consumed methadone the lowest dose immediately elicited pronounced oral dyskinesias virtually identical to those of human tardive dyskinesia. The control monkeys did not exhibit oral dyskinesias even after prolonged treatment with the highest dose. The clincial implications may be related to the functioning of brain dopaminergic systems.