Optimization of Covalent MKK7 Inhibitors via Crude Nanomole-Scale Libraries

High-throughput nanomole-scale synthesis allows for late-stage functionalization (LSF) of compounds in an efficient and economical manner. Here, we demonstrated that copper-catalyzed azide-alkyne cycloaddition could be used for the LSF of covalent kinase inhibitors at the nanoscale, enabling the synthesis of hundreds of compounds that did not require purification for biological assay screening, thus reducing experimental time drastically. We generated crude libraries of inhibitors for the kinase MKK7, derived from two different parental precursors, and analyzed them via the high-throughput In-Cell Western assay. Select inhibitors were resynthesized, validated via conventional biological and biochemical methods such as western blots and liquid chromatography-mass spectrometry (LC-MS) labeling, and successfully co-crystallized. Two of these compounds showed over 20-fold increased inhibitory activity compared to the parental compound. This study demonstrates that high-throughput LSF of covalent inhibitors at the nanomole-scale level can be an auspicious approach in improving the properties of lead chemical matter.

Site-Specific Labeling of Endogenous Proteins Using CoLDR Chemistry

Chemical modifications of native proteins can affect their stability, activity, interactions, localization, and more. However, there are few nongenetic methods for the installation of chemical modifications at a specific protein site in cells. Here we report a covalent ligand directed release (CoLDR) site-specific labeling strategy, which enables the installation of a variety of functional tags on a target protein while releasing the directing ligand. Using this approach, we were able to label various proteins such as BTK, K-Ras^G12C, and SARS-CoV-2 PL^pro with different tags. For BTK we have shown selective labeling in cells of both alkyne and fluorophores tags. Protein labeling by traditional affinity methods often inhibits protein activity since the directing ligand permanently occupies the target binding pocket. We have shown that using CoLDR chemistry, modification of BTK by these probes in cells preserves its activity. We demonstrated several applications for this approach including determining the half-life of BTK in its native environment with minimal perturbation, as well as quantification of BTK degradation by a noncovalent proteolysis targeting chimera (PROTAC) by in-gel fluorescence. Using an environment-sensitive “turn-on” fluorescent probe, we were able to monitor ligand binding to the active site of BTK. Finally, we have demonstrated efficient CoLDR-based BTK PROTACs (DC₅₀ < 100 nM), which installed a CRBN binder onto BTK. This approach joins very few available labeling strategies that maintain the target protein activity and thus makes an important addition to the toolbox of chemical biology.

SARS-CoV-2 infects the human kidney and drives fibrosis in kidney organoids

Kidney failure is frequently observed during and after COVID-19, but it remains elusive whether this is a direct effect of the virus. Here, we report that SARS-CoV-2 directly infects kidney cells and is associated with increased tubule-interstitial kidney fibrosis in patient autopsy samples. To study direct effects of the virus on the kidney independent of systemic effects of COVID-19, we infected human-induced pluripotent stem-cell-derived kidney organoids with SARS-CoV-2. Single-cell RNA sequencing indicated injury and dedifferentiation of infected cells with activation of profibrotic signaling pathways. Importantly, SARS-CoV-2 infection also led to increased collagen 1 protein expression in organoids. A SARS-CoV-2 protease inhibitor was able to ameliorate the infection of kidney cells by SARS-CoV-2. Our results suggest that SARS-CoV-2 can directly infect kidney cells and induce cell injury with subsequent fibrosis. These data could explain both acute kidney injury in COVID-19 patients and the development of chronic kidney disease in long COVID.

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COVID-19 patients present tubulo-interstitial kidney fibrosis compared with controls

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SARS-CoV-2 infection stimulates profibrotic signaling in human kidney organoids

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SARS-CoV-2 infection can be inhibited by a protease blocker in human kidney organoids

Sulfopin is a covalent inhibitor of Pin1 that blocks Myc-driven tumors in vivo

The peptidyl-prolyl isomerase, Pin1, is exploited in cancer to activate oncogenes and inactivate tumor suppressors. However, despite considerable efforts, Pin1 has remained an elusive drug target. Here, we screened an electrophilic fragment library to identify covalent inhibitors targeting Pin1's active site Cys113, leading to the development of Sulfopin, a nanomolar Pin1 inhibitor. Sulfopin is highly selective, as validated by two independent chemoproteomics methods, achieves potent cellular and in vivo target engagement and phenocopies Pin1 genetic knockout. Pin1 inhibition had only a modest effect on cancer cell line viability. Nevertheless, Sulfopin induced downregulation of c-Myc target genes, reduced tumor progression and conferred survival benefit in murine and zebrafish models of MYCN-driven neuroblastoma, and in a murine model of pancreatic cancer. Our results demonstrate that Sulfopin is a chemical probe suitable for assessment of Pin1-dependent pharmacology in cells and in vivo, and that Pin1 warrants further investigation as a potential cancer drug target.

An automatic pipeline for the design of irreversible derivatives identifies a potent SARS-CoV-2 Mpro inhibitor

Designing covalent inhibitors is increasingly important, although it remains challenging. Here, we present covalentizer, a computational pipeline for identifying irreversible inhibitors based on structures of targets with non-covalent binders. Through covalent docking of tailored focused libraries, we identify candidates that can bind covalently to a nearby cysteine while preserving the interactions of the original molecule. We found ∼11,000 cysteines proximal to a ligand across 8,386 complexes in the PDB. Of these, the protocol identified 1,553 structures with covalent predictions. In a prospective evaluation, five out of nine predicted covalent kinase inhibitors showed half-maximal inhibitory concentration (IC₅₀) values between 155 nM and 4.5 μM. Application against an existing SARS-CoV M^pro reversible inhibitor led to an acrylamide inhibitor series with low micromolar IC₅₀ values against SARS-CoV-2 M^pro. The docking was validated by 12 co-crystal structures. Together these examples hint at the vast number of covalent inhibitors accessible through our protocol.

Tunable Methacrylamides for Covalent Ligand Directed Release Chemistry

Targeted covalent inhibitors are an important class of drugs and chemical probes. However, relatively few electrophiles meet the criteria for successful covalent inhibitor design. Here we describe α-substituted methacrylamides as a new class of electrophiles suitable for targeted covalent inhibitors. While typically α-substitutions inactivate acrylamides, we show that hetero α-substituted methacrylamides have higher thiol reactivity and undergo a conjugated addition-elimination reaction ultimately releasing the substituent. Their reactivity toward thiols is tunable and correlates with the pKa/pKb of the leaving group. In the context of the BTK inhibitor ibrutinib, these electrophiles showed lower intrinsic thiol reactivity than the unsubstituted ibrutinib acrylamide. This translated to comparable potency in protein labeling, in vitro kinase assays, and functional cellular assays, with improved selectivity. The conjugate addition-elimination reaction upon covalent binding to their target cysteine allows functionalizing α-substituted methacrylamides as turn-on probes. To demonstrate this, we prepared covalent ligand directed release (CoLDR) turn-on fluorescent probes for BTK, EGFR, and K-RasG12C. We further demonstrate a BTK CoLDR chemiluminescent probe that enabled a high-throughput screen for BTK inhibitors. Altogether we show that α-substituted methacrylamides represent a new and versatile addition to the toolbox of targeted covalent inhibitor design.

Crystallographic and electrophilic fragment screening of the SARS-CoV-2 main protease

COVID-19, caused by SARS-CoV-2, lacks effective therapeutics. Additionally, no antiviral drugs or vaccines were developed against the closely related coronavirus, SARS-CoV-1 or MERS-CoV, despite previous zoonotic outbreaks. To identify starting points for such therapeutics, we performed a large-scale screen of electrophile and non-covalent fragments through a combined mass spectrometry and X-ray approach against the SARS-CoV-2 main protease, one of two cysteine viral proteases essential for viral replication. Our crystallographic screen identified 71 hits that span the entire active site, as well as 3 hits at the dimer interface. These structures reveal routes to rapidly develop more potent inhibitors through merging of covalent and non-covalent fragment hits; one series of low-reactivity, tractable covalent fragments were progressed to discover improved binders. These combined hits offer unprecedented structural and reactivity information for on-going structure-based drug design against SARS-CoV-2 main protease.

Structure and Electron-Transfer Pathway of the Human Methionine Sulfoxide Reductase MsrB3

Aims: The post-translational oxidation of methionine to methionine sulfoxide (MetSO) is a reversible process, enabling the repair of oxidative damage to proteins and the use of sulfoxidation as a regulatory switch. MetSO reductases catalyze the stereospecific reduction of MetSO. One of the mammalian MetSO reductases, MsrB3, has a signal sequence for entry into the endoplasmic reticulum (ER). In the ER, MsrB3 is expected to encounter a distinct redox environment compared with its paralogs in the cytosol, nucleus, and mitochondria. We sought to determine the location and arrangement of MsrB3 redox-active cysteines, which may couple MsrB3 activity to other redox events in the ER. Results: We determined the human MsrB3 structure by using X-ray crystallography. The structure revealed that a disulfide bond near the protein amino terminus is distant in space from the active site. Nevertheless, biochemical assays showed that these amino-terminal cysteines are oxidized by the MsrB3 active site after its reaction with MetSO. Innovation: This study reveals a mechanism to shuttle oxidizing equivalents from the primary MsrB3 active site toward the enzyme surface, where they would be available for further dithiol-disulfide exchange reactions. Conclusion: Conformational changes must occur during the MsrB3 catalytic cycle to transfer oxidizing equivalents from the active site to the amino-terminal redox-active disulfide. The accessibility of this exposed disulfide may help couple MsrB3 activity to other dithiol-disulfide redox events in the secretory pathway.

In crystallo-screening for discovery of human norovirus 3C-like protease inhibitors

Outbreaks of human epidemic nonbacterial gastroenteritis are mainly caused by noroviruses. Viral replication requires a 3C-like cysteine protease (3CLpro) which processes the 200 kDa viral polyprotein into six functional proteins. The 3CLpro has attracted much interest due to its potential as a target for antiviral drugs. A system for growing high-quality crystals of native Southampton norovirus 3CLpro (SV3CP) has been established, allowing the ligand-free crystal structure to be determined to 1.3 Å in a tetrameric state. This also allowed crystal-based fragment screening to be performed with various compound libraries, ultimately to guide drug discovery for SV3CP. A total of 19 fragments were found to bind to the protease out of the 844 which were screened. Two of the hits were located at the active site of SV3CP and showed good inhibitory activity in kinetic assays. Another 5 were found at the enzyme's putative RNA-binding site and a further 11 were located in the symmetric central cavity of the tetramer.

Rapid Covalent-Probe Discovery by Electrophile-Fragment Screening

Covalent probes can display unmatched potency, selectivity, and duration of action; however, their discovery is challenging. In principle, fragments that can irreversibly bind their target can overcome the low affinity that limits reversible fragment screening, but such electrophilic fragments were considered nonselective and were rarely screened. We hypothesized that mild electrophiles might overcome the selectivity challenge and constructed a library of 993 mildly electrophilic fragments. We characterized this library by a new high-throughput thiol-reactivity assay and screened them against 10 cysteine-containing proteins. Highly reactive and promiscuous fragments were rare and could be easily eliminated. In contrast, we found hits for most targets. Combining our approach with high-throughput crystallography allowed rapid progression to potent and selective probes for two enzymes, the deubiquitinase OTUB2 and the pyrophosphatase NUDT7. No inhibitors were previously known for either. This study highlights the potential of electrophile-fragment screening as a practical and efficient tool for covalent-ligand discovery.

cis-Proline mutants of quiescin sulfhydryl oxidase 1 with altered redox properties undermine extracellular matrix integrity and cell adhesion in fibroblast cultures

The thioredoxin superfamily has expanded and diverged extensively throughout evolution such that distant members no longer show appreciable sequence homology. Nevertheless, redox-active thioredoxin-fold proteins functioning in diverse physiological contexts often share canonical amino acids near the active-site (di-)cysteine motif. Quiescin sulfhydryl oxidase 1 (QSOX1), a catalyst of disulfide bond formation secreted by fibroblasts, is a multi-domain thioredoxin superfamily enzyme with certain similarities to the protein disulfide isomerase (PDI) enzymes. Among other potential functions, QSOX1 supports extracellular matrix assembly in fibroblast cultures. We introduced mutations at a cis-proline in QSOX1 that is conserved across the thioredoxin superfamily and was previously observed to modulate redox interactions of the bacterial enzyme DsbA. The resulting QSOX1 variants showed a striking detrimental effect when added exogenously to fibroblasts: they severely disrupted the extracellular matrix and cell adhesion, even in the presence of naturally secreted, wild-type QSOX1. The specificity of this phenomenon for particular QSOX1 mutants inspired an investigation of the effects of mutation on catalytic and redox properties. For a series of QSOX1 mutants, the detrimental effect correlated with the redox potential of the first redox-active site, and an X-ray crystal structure of one of the mutants revealed the reorganization of the cis-proline loop caused by the mutations. Due to the conservation of the mutated residues across the PDI family and beyond, insights obtained in this study may be broadly applicable to a variety of physiologically important redox-active enzymes. IMPACT STATEMENT: We show that mutation of a conserved cis-proline amino acid, analogous to a mutation used to trap substrates of a bacterial disulfide catalyst, has a dramatic effect on the physiological function of the mammalian disulfide catalyst QSOX1. As the active-site region of QSOX1 is shared with the large family of protein disulfide isomerases in humans, the effects of such mutations on redox properties, enzymatic activity, and biological targeting may be relevant across the family.

Burden of copy number variation in common variable immunodeficiency

Common variable immunodeficiency (CVID) has been associated recently with a dramatic increase in total copy number variation burden, the cause of which is unclear. In order to explore further the origin and clinical relevance of this finding, we quantified the total genomic copy number variation (CNV) burden in affected patients and evaluated clinical details in relationship to total CNV burden. No correlation was found between total CNV burden and either patient age or time elapsed since symptom onset, and higher total burden did not correlate with incidence of malignancy or other subphenotypes. These findings suggest that the increased CNV burden is static and intrinsic to CVID as a disease.

Differential teratogenesis of all-trans-retinoic acid administered on gestational day 9.5 to SWV and C57BL/6N mice: Emphasis on limb dysmorphology

BACKGROUND

Mouse strain differences in teratologic response are well documented. However, because retinoids cause similar malformation syndromes across many species, the strain differences may be predicted to be minimal. The goals of this study were to characterize and explain the differences between the C57BL/6N and SWV mouse strains in terms of all-trans-retinoic acid (RA)-induced teratologic effects at the time of gestation that cause postaxial forelimb ectrodactyly.

METHODS

Visceral and skeletal malformations were determined by Wilson's sectioning and double-staining techniques, respectively; developmental staging was performed according to the somite count; and retinoid concentrations were assessed by HPLC.

RESULTS

C57BL/6N mice were more susceptible than SWV mice to induction of embryolethality, cardiovascular defects, and forelimb ectrodactyly, whereas the opposite was true for the induction of ear, thymus, and tail agenesis, and cleft palate, gastroschisis, and anal atresia. As determined by somite counts, 1 strain intercross was developmentally advanced compared to the parental strains and the reciprocal cross. Retinoid susceptibility was equivalent between the reciprocal crosses for some malformations and determined by the maternal genotype for others. Toxicokinetic experiments showed that whole-embryo peak retinoid concentrations did not differ between the strains, but the area under the curve (AUC) for all-trans-RA was 1.3 times higher in C57BL/6N than in SWV embryos.

CONCLUSIONS

The malformation spectrum induced by RA was strain-specific, and the strain sensitivity for forelimb ectrodactyly was consistent with all previously tested teratogenic agents (i.e., C57BL/6N was more sensitive than SWV). The strain differences in teratologic effects were not explained by developmental timing differences or toxicokinetic differences at the whole-embryo level.

Buprenorphine treatment of heroin dependence (detoxification and maintenance) in a private practice setting

At the conclusion of a 3-year demonstration project in a medical setting in which refusal to accept methadone was an inclusion criterion, 12 subjects were unable to detoxify from buprenorphine and remained adamant in their refusal to enroll in a MMTP. In order to study the feasibility of expanding opportunities for treatment previously unavailable to this under-served population of heroin addicts, these 12 subjects plus an additional 11 subjects (N = 23) were recruited for a 12 months trial of buprenorphine treatment conducted in an office-based setting on a fee-for-service basis. An additional cohort of 40 heroin dependent subjects were entered in a protocol for detoxification only. The findings demonstrate both feasibility and patient acceptance of office based fee-for-service buprenorphine treatment, supporting the need for (1) additional studies of this population and (2) changes in government regulations to reintroduce addiction treatment under physician auspices in private practice settings.

Exacerbation of acetazolamide teratogenesis by amiloride and its analogs active against Na+/H+ exchangers and Na+ channels

Postaxial forelimb ectrodactyly induced by acetazolamide given on Day 9.5 of murine gestation is thought to be mediated by reduced intracellular pH (pHi) within the limb bud. Coadministration of amiloride increases the incidence and severity of acetazolamide-induced forelimb malformations and further reduces limb bud pHi. These findings were hypothesized to be attributable to the action of amiloride as an inhibitor of Na+/H+ exchangers (NHEs), plasma membrane-localized proteins involved in the maintenance of cellular pH homeostasis. Here, we explored this hypothesis further by coadministering with acetazolamide, amiloride, or analogs known to preferentially inhibit NHEs 5-(N-methyl-N-isobutyl)-amiloride, 5-(N, N-hexamethylene)-amiloride, 5-(N, N-dimethyl)-amiloride, and 5-(N-ethyl-N-isopropyl)-amiloride or amiloride-sensitive Na+ channels (benzamil). The coadministration of either amiloride, benzamil, 5-(N, N-dimethyl)-amiloride, 5-(N-ethyl-N-isopropyl)-amiloride, or 5-(N-methyl-N-isobutyl)-amiloride all dose responsively increased the frequency and severity of forelimb malformations compared to acetazolamide alone. None of the analogs given alone induced forelimb ectrodactyly. The data are consistent with the original hypothesis that the exacerbation of acetazolamide teratogenesis is due to NHE inhibition. Surprisingly, benzamil was the most potent potentiator of acetazolamide teratogenesis. This result strongly suggests that amiloride-sensitive Na+ channels are also present within the murine embryo and are likely to play a role in pHi homeostasis.

Cardiovascular alterations in rat fetuses exposed to calcium channel blockers

Preclinical toxicologic investigation suggested that a new calcium channel blocker, Ro 40-5967, induced cardiovascular alterations in rat fetuses exposed to this agent during organogenesis. The present study was designed to investigate the hypothesis that calcium channel blockers in general induce cardiovascular malformations indicating a pharmacologic class effect. We studied three calcium channel blockers of different structure, nifedipine, diltiazem, and verapamil, along with the new agent. Pregnant rats were administered one of these calcium channel blockers during the period of cardiac morphogenesis and the offspring examined on day 20 of gestation for cardiovascular malformations. A low incidence of cardiovascular malformations was observed after exposure to each of the four calcium channel blockers, but this incidence was statistically significant only for verapamil and nifedipine. All four agents were associated with aortic arch branching variants, although significantly increased only for Ro 40-5967 and verapamil.

Cocaine-induced embryonic cardiovascular disruption in mice

The purpose of this study was to determine whether vascular disruption is a feature of cocaine-induced teratogenicity in early murine organogenesis. The embryotoxic effects of cocaine were assessed: (1) in vivo, (2) in embryos cultured in the presence of cocaine (in vitro), and (3) after cocaine was administered in vivo and the embryos subsequently cultured in the absence of cocaine (in vivo-in vitro). When cocaine (78 mg/kg) was administered in vivo on day 8 and embryos were assessed on day 10, significant vascular perturbations, in the form of vasodilation and hemorrhage, as well as neural defects, were observed. In the in vitro system, day 8 embryos were cultured for 48 hr in the presence of 0, 10, 20, 33, and 66 micrograms/ml cocaine. At 10 and 20 micrograms/ml, vascular perturbation was not seen, while at higher cocaine concentrations, development of the yolk sac vasculature was inhibited. Hemorrhage was not a feature of in vitro cocaine embryotoxicity. However, significantly increased incidences of neural defects were seen at concentrations of 20 micrograms/ml or greater. Finally, in the in vivo-in vitro system, 78 mg/kg cocaine was administered on day 8 in vivo and embryos were dissected after 15 min and cultured for 48 hr. Marked cardiovascular perturbation, as well as neural defects, were produced using this protocol. With cocaine treatment, only 26.6% of embryos had a functioning heartbeat and yolk sac circulation, compared to 85.6% of controls. This cardiovascular disruption was associated with pooling of blood in the embryo, with 59.9% of embryos exhibiting marked vasodilation and hemorrhage compared to 12.5% in controls. Additional manifestations of cardiovascular perturbation were edema and blisters observed in cocaine-treated embryos. Neural tube defects, including open neural tube (8.3%) and microcephaly/hypoplastic prosencephalon (30.0%), were also significantly increased in cocaine-treated embryos. The cardiovascular and neural effects produced by cocaine were dose-dependent (40, 20 mg/kg). Thus, administration of cocaine in the in vivo or in vivo-in vitro systems produced marked cardiovascular effects, while in vitro treatment did not. These results suggest that cocaine may elicit cardiovascular toxicity through a maternally mediated mechanism.

Role of oxygen free radicals in cocaine-induced vascular disruption in mice

To test the hypothesis that cocaine-induced embryonic vascular disruption is mediated by oxygen free radicals, the antioxidants 2-oxothiazolidine-4-carboxylate (OTC) and alpha-phenyl-N-t-butyl nitrone (PBN) were employed. When cocaine (78 mg/kg) was administered on day 8 of gestation to ICR mice and embryos evaluated on day 10 (in vivo), 62.3% of cocaine-treated embryos showed increased vasodilation compared to 4.9% for controls, and 33.1% of the cocaine-exposed embryos showed marked hemorrhage compared to 3.3% for controls. In addition, cocaine increased the incidence of neural defects, in the form of open neural tube, hypoplastic prosencephalon, and microcephaly. Administration of OTC (0.25 and 0.5 mmol/kg) or PBN (300 mg/kg) prior to cocaine significantly reduced cocaine-induced vasodilation and hemorrhage, while not preventing neural defects. When cocaine (78 mg/kg) was administered in vivo on day 8 of gestation and embryos were dissected 15 min later and subsequently cultured for 48 hr in the absence of cocaine (in vivo-in vitro), marked vascular disruption was observed: normal yolk circulation/heartbeat was decreased to 26.6%, while edema/blisters and vasodilation/hemorrhage were increased to 45.6% and 59.6%, respectively. Administration of PBN (300 mg/kg) prior to cocaine completely prevented cocaine-induced vascular disruption. When cocaine was administered in vivo and PBN (300 micrograms/ml) was incubated with cultured embryos in vitro, the antioxidant only partially prevented cocaine-induced cardiovascular defects in this model. Neural defects produced by cocaine were not significantly affected by PBN, administered either in vivo or in vitro. Cocaine (78 mg/kg) administered in vivo stimulated lipid peroxidation maximally after 3 hr in both day 8 and day 9 embryos. When cocaine was incubated in vitro during embryo culture at 33 micrograms/ml, a concentration that produces nonspecific inhibition of growth and development, embryonic lipid peroxidation on day 9 was not affected. Finally, when PBN (300 mg/kg) was administered prior to cocaine (78 mg/kg) on day 8 of gestation, stimulation of lipid peroxidation by cocaine was prevented. These results suggest that cocaine-induced vascular disruption in early development is mediated by maternal production of oxygen free radicals.

The effect of administration time on malformations induced by three anticonvulsant agents in C57BL/6J mice with emphasis on forelimb ectrodactyly

Exposure of C57BL/6J mice to three anticonvulsant derivatives, namely, dimethadione, sodium valproate, and sodium diphenylhydantoin, each induced postaxial forelimb ectrodactyly. The agents were administered at gestational days 9, 9 1/3, 9 2/3, and 10. It was determined that administration at day 9 2/3 induced the highest percentage of forelimb ectrodactyly for each of the three agents. The forelimb ectrodactyly response in the C57BL/6J strain was compared with the A/J strain (Collins et al., Teratology, 41:61-70, 1990); it was found that the C57BL/6J strain was more sensitive to dimethadione and the A/J strain was more sensitive to diphenylhydantoin and sodium valproate. The position of vertebral defects induced by sodium valproate correlated with the time of drug administration. The overall syndrome of malformations induced by the three anticonvulsant agents was relatively similar in the two mouse strains and differed between each of the anticonvulsant agents.

Buprenorphine responders: a diagnostic subgroup of heroin addicts?

1. A 26-32 month follow-up of 16 heroin-dependent subjects who entered a pilot trial of treatment with buprenorphine (a mixed agonist/antagonist) suggests that positive response to treatment may identify a subgroup of untreated addicts whose levels of psychosocial functioning are intermediate between those for whom methadone (a pure agonist) or naltrexone (a pure antagonist) would be indicated. 2. Buprenorphine's pharmacologic profile provides a missing link in available modalities for opiate dependence treatment, making it acceptable for many addicts who will not accept methadone maintenance treatment, join a residential therapeutic community, or be successful on naltrexone treatment. 3. Eight of the 16 ss were abstinent from heroin while receiving 0.6-3.9 mg/day buprenorphine and counseling. Responders (mean age 34 yrs) had been heroin dependent for a mean of 9.5 years (range 6-17 yrs), all were self-supporting, 4 lived with a non-addicted spouse, 5 had no prior treatment for addiction and 3 had prior naltrexone treatment, but had discontinued it and relapsed. Non-responders (mean age 30 yrs) had been heroin dependent for a mean of 7.4 yrs (range 2-19 yrs), 7 had no regular employment, all were single and 7 had no prior treatment for addiction. 4. Levels of psychosocial functioning (work, home, leisure) and global assessments of functioning were significantly higher for buprenorphine responders than non-responders (p less than .001 and p less than .01 respectively). 5. A new formulation of buprenorphine needs to be developed for addiction treatment, ideally consisting of 0.5 mg and 2.0 mg sublingual tablets.

Methadone and naltrexone in the treatment of heroin dependence

Over the past 20 years, methadone maintenance has been shown to be a safe, effective treatment for large numbers of heroin addicts. The majority of patients derive major benefits while in treatment, most measurably in the areas of decreased use of illicit opiates, diminished criminality, increased levels of employment and more stable interpersonal relationships. An advantage of methadone maintenance over other treatments is that it attracts and retains a relatively large segment of the addict population and is reasonably cost-effective. Naltrexone is well suited as a transitional treatment for individuals who have progressed using methadone maintenance. Patients completing a course of methadone maintenance should be encouraged to use naltrexone during the postmethadone period, when symptoms of protracted abstinence often lead them to reinitiate use of heroin. Those with stable family relationships, good jobs, minimal antisocial behavior, and low drug-craving before beginning a course of naltrexone appear to benefit most from the treatment. Rates of retention improve when naltrexone is used within a comprehensive rehabilitation program. Although addicted individuals are often stereotyped, they are, in fact, a heterogeneous group representing a range of psychopathologies and life situations. Thus, within any one facility, a variety of modalities should be available to allow treatment to be tailored to the individual. No single treatment is best for all patients, and, moreover, the preferred modality for any one individual may change over time as a result of progress in treatment or varying life circumstances. Multimodality programs that include methadone and naltrexone enable the maximal number of individuals to benefit from treatment.