NIDA Clinical Trials Network CTN-0051, Extended-Release Naltrexone vs. Buprenorphine for Opioid Treatment (X:BOT): Study design and rationale.

For opioid-dependent patients in the US and elsewhere, detoxification and counseling-only aftercare are treatment mainstays. Long-term abstinence is rarely achieved; many patients relapse and overdose after detoxification. Methadone, buprenorphine-naloxone (BUP-NX) and extended-release naltrexone (XR-NTX) can prevent opioid relapse but are underutilized. This study is intended to develop an evidence-base to help patients and providers make informed choices and to foster wider adoption of relapse-prevention pharmacotherapies. The National Institute on Drug Abuse's Clinical Trials Network (CTN) study CTN-0051, X:BOT, is a comparative effectiveness study of treatment for 24weeks with XR-NTX, an opioid antagonist, versus BUP-NX, a high affinity partial opioid agonist, for opioid dependent patients initiating treatment at 8 short-term residential (detoxification) units and continuing care as outpatients. Up to 600 participants are randomized (1:1) to XR-NTX or BUP-NX. The primary outcome is time to opioid relapse (i.e., loss of persistent abstinence) across the 24-week treatment phase. Differences between arms in the distribution of time-to-relapse will be compared (construction of the asymptotic 95% CI for the hazard ratio of the difference between arms). Secondary outcomes include proportions retained in treatment, rates of opioid abstinence, adverse events, cigarette, alcohol, and other drug use, and HIV risk behaviors; opioid cravings, quality of life, cognitive function, genetic moderators, and cost effectiveness. XR-NTX and BUP-NX differ considerably in their characteristics and clinical management; no studies to date have compared XR-NTX with buprenorphine maintenance. Study design choices and compromises inherent to a comparative effectiveness trial of distinct treatment regimens are reviewed. NCT02032433.

Lee JD ，Nunes EV ，Mpa PN ，Bailey GL ，Brigham GS ，Cohen AJ ，Fishman M ，Ling W ，Lindblad R ，Shmueli-Blumberg D ，Stablein D ，May J ，Salazar D ，Liu D ，Rotrosen J ... -  《-》

Comparative effectiveness of extended-release naltrexone versus buprenorphine-naloxone for opioid relapse prevention (X:BOT): a multicentre, open-label, randomised controlled trial.

Extended-release naltrexone (XR-NTX), an opioid antagonist, and sublingual buprenorphine-naloxone (BUP-NX), a partial opioid agonist, are pharmacologically and conceptually distinct interventions to prevent opioid relapse. We aimed to estimate the difference in opioid relapse-free survival between XR-NTX and BUP-NX. We initiated this 24 week, open-label, randomised controlled, comparative effectiveness trial at eight US community-based inpatient services and followed up participants as outpatients. Participants were 18 years or older, had Diagnostic and Statistical Manual of Mental Disorders-5 opioid use disorder, and had used non-prescribed opioids in the past 30 days. We stratified participants by treatment site and opioid use severity and used a web-based permuted block design with random equally weighted block sizes of four and six for randomisation (1:1) to receive XR-NTX or BUP-NX. XR-NTX was monthly intramuscular injections (Vivitrol; Alkermes) and BUP-NX was daily self-administered buprenorphine-naloxone sublingual film (Suboxone; Indivior). The primary outcome was opioid relapse-free survival during 24 weeks of outpatient treatment. Relapse was 4 consecutive weeks of any non-study opioid use by urine toxicology or self-report, or 7 consecutive days of self-reported use. This trial is registered with ClinicalTrials.gov, NCT02032433. Between Jan 30, 2014, and May 25, 2016, we randomly assigned 570 participants to receive XR-NTX (n=283) or BUP-NX (n=287). The last follow-up visit was Jan 31, 2017. As expected, XR-NTX had a substantial induction hurdle: fewer participants successfully initiated XR-NTX (204 [72%] of 283) than BUP-NX (270 [94%] of 287; p<0·0001). Among all participants who were randomly assigned (intention-to-treat population, n=570) 24 week relapse events were greater for XR-NTX (185 [65%] of 283) than for BUP-NX (163 [57%] of 287; hazard ratio [HR] 1·36, 95% CI 1·10-1·68), most or all of this difference accounted for by early relapse in nearly all (70 [89%] of 79) XR-NTX induction failures. Among participants successfully inducted (per-protocol population, n=474), 24 week relapse events were similar across study groups (p=0·44). Opioid-negative urine samples (p<0·0001) and opioid-abstinent days (p<0·0001) favoured BUP-NX compared with XR-NTX among the intention-to-treat population, but were similar across study groups among the per-protocol population. Self-reported opioid craving was initially less with XR-NTX than with BUP-NX (p=0·0012), then converged by week 24 (p=0·20). With the exception of mild-to-moderate XR-NTX injection site reactions, treatment-emergent adverse events including overdose did not differ between treatment groups. Five fatal overdoses occurred (two in the XR-NTX group and three in the BUP-NX group). In this population it is more difficult to initiate patients to XR-NTX than BUP-NX, and this negatively affected overall relapse. However, once initiated, both medications were equally safe and effective. Future work should focus on facilitating induction to XR-NTX and on improving treatment retention for both medications. NIDA Clinical Trials Network.

Lee JD ，Nunes EV Jr ，Novo P ，Bachrach K ，Bailey GL ，Bhatt S ，Farkas S ，Fishman M ，Gauthier P ，Hodgkins CC ，King J ，Lindblad R ，Liu D ，Matthews AG ，May J ，Peavy KM ，Ross S ，Salazar D ，Schkolnik P ，Shmueli-Blumberg D ，Stablein D ，Subramaniam G ，Rotrosen J ... -  《-》

Buprenorphine-naloxone vs. extended-release naltrexone for opioid use disorder in individuals with and without criminal legal involvement: A secondary analysis of the X:BOT randomized controlled trial.

There is uncertainty about whether criminal legal involvement (CLI) impacts the effectiveness of medications for opioid use disorder (MOUD). We aimed to determine whether CLI modifies the association between buprenorphine-naloxone (BUP-NX) vs. extended-release naltrexone (XR-NTX) and MOUD treatment outcomes. We conducted a secondary analysis of X:BOT, a 24-week multi-center randomized controlled trial comparing treatment outcomes between BUP-NX (n = 287) and XR-NTX (n = 283) in the general population. We used baseline Additional Severity-Index Lite responses to identify patients with recent CLI (n = 342), defined as active CLI and/or CLI in the past 30 days, and lifetime incarceration (n = 328). We explored recent CLI and lifetime incarceration as potential effect modifiers of BUP-NX vs. XR-NTX effectiveness on relapse, induction, and overdose. We conducted both intention-to-treat and per-protocol analyses for each outcome. In intention-to-treat analyses, recent CLI modified the effect of BUP-NX vs. XR-NTX on odds of successful induction (p = 0.03) and hazard of overdose (p = 0.04), but it did not modify the effect on hazard of relapse (p = 0.23). All participants experienced lower odds of successful induction with XR-NTX compared to BUP-NX, but the relative likelihood of successful induction with BUP-NX was lower than XR-NTX among individuals with recent CLI (OR: 0.25, 95 % CI: 0.13-0.47, p < 0.001) compared to those without recent CLI (OR: 0.04, 95 % CI: 0.01-0.19, p < 0.001). Participants with recent CLI experienced similar hazard of overdose with XR-NTX and BUP-NX (HR: 1.12, 95 % CI: 0.42-3.01, p = 0.82), whereas those without recent CLI experienced greater hazard of overdose with XR-NTX compared to BUP-NX (HR: 12.60, 95 % CI: 1.62-98.03, p = 0.02). In per-protocol analyses, recent CLI did not modify the effect of MOUD on hazard of overdose (p = 0.10) or relapse (p = 0.41). Lifetime incarceration did not modify any outcome. Compared to individuals without recent CLI, individuals with recent CLI experienced decreased relative effectiveness of BUP-NX compared to XR-NTX for induction and overdose outcomes. This highlights the importance of considering the impact of recent CLI on opioid use disorder treatment outcomes. Future research should explore the mechanisms through which recent CLI modifies MOUD effectiveness and aim to improve MOUD effectiveness for individuals with recent CLI.

Balter DR ，Puglisi LB ，Dziura J ，Fiellin DA ，Howell BA ... -  《-》

Is extended release naltrexone superior to buprenorphine-naloxone to reduce drinking among outpatients receiving treatment for opioid use disorder? A secondary analysis of the CTN X:BOT trial.

The comparative effectiveness of extended-release naltrexone versus buprenorphine-naloxone for opioid relapse prevention (X:BOT) trial showed that following induction, treatment with the sublingual agonist (buprenorphine-naloxone, BUP-NX) or injected antagonist (extended release naltrexone, XR-NTX) produced similar reductions in opioid relapse in injection users with opioid use disorder (OUD). Because XR-NTX reduces drinking in alcohol use disorder (AUD), we conducted a secondary analysis of the X:BOT sample of patients successfully inducted onto treatment to determine whether XR-NTX (n = 204) was superior to BUP-NX (n = 270) in reducing drinking or heavy drinking in patients with OUD. Standard drink units consumed were measured using the Timeline Follow-back method. Mixed-models regression was used to examine the monthly frequency of any drinking and heavy drinking over 6 months of treatment. We used a proportional hazard survival analysis to examine the time to first drink. Both treatment groups reduced drinking from baseline to posttreatment (small to medium effect), but no differences between groups were detected. However, only 29% (n = 136) of the sample had AUD and 19% (n = 26/136) of those were abstinent before treatment. Analysis of a subsample enriched for possible drinking included 136 individuals with an AUD diagnosis plus 43 who did not have AUD, but reported at least one day of heavy drinking prior to the study. However, this subsample reported only 32% of days of any drinking with a median of only 13% of days designated as "heavy." Within this subsample, at baseline, the BUP-NX group reported more mean drinks per drinking day than the XR-NTX group (p = 0.03); however, there were no other significant group differences on drinking observed before, during, or at the end of treatment. There was an overall reduction in drinking during treatment of OUD using both agonist and antagonist medications, so that the hypothesis that XR-NTX would be superior to BUP-NX was not supported. The study is limited by low levels of comorbid AUD or heavy drinking observed in X:BOT trial participants seeking treatment for OUD.

Roache JD ，Pavlicova M ，Campbell A ，Choo TH ，Peavy M ，Kermack AS ，Nunes EV Jr ，Rotrosen J ... -  《-》

Cost-effectiveness implications of increasing the efficiency of the extended-release naltrexone induction process for the treatment of opioid use disorder: a secondary analysis.

In a US randomized-effectiveness trial comparing extended-release naltrexone (XR-NTX) with buprenorphine-naloxone (BUP-NX) for the prevention of opioid relapse among participants recruited during inpatient detoxification (CTN-0051), the requirement to complete opioid detoxification prior to initiating XR-NTX resulted in lower rates of initiation of XR-NTX (72% XR-NTX versus 94% BUP-NX). This was a retrospective secondary analysis of CTN-0051 trial data, including follow-up data over 24-36 weeks. Eight community-based, inpatient-detoxification and follow-up outpatient treatment facilities in the United States. A total of 283 participants randomized to receive XR-NTX. Efficiency was estimated using a multivariable generalized structural equation model to explore simultaneous determinants of XR-NTX induction and induction duration (detoxification + residential days). Cost-effectiveness was estimated from the health-care sector perspective and included expected costs and quality-adjusted life-years (QALYs). Treatment site was the only modifiable factor that simultaneously increased the likelihood of XR-NTX induction and decreased induction duration. Incorporating the higher predicted probability of XR-NTX induction, and fewer predicted days of detoxification and subsequent residential treatment into the cost-effectiveness framework, reduced the incremental average 24-week total cost of XR-NTX treatment from $5317 more than that of BUP-NX (P = 0.01) to a non-statistically-significant difference of $1016 (P = 0.63). QALYs gained remained similar across arms. Adopting an efficient model of extended-release naltrexone initiation could result in extended-release naltrexone and buprenorphine-naloxone being of comparable economic value from the health-care sector perspective over 24-36 weeks for patients seeking treatment for opioid use disorder at an inpatient detoxification facility.

Murphy SM ，Jeng PJ ，McCollister KE ，Leff JA ，Jalali A ，Shulman M ，Lee JD ，Nunes EV ，Novo P ，Rotrosen J ，Schackman BR ... -  《-》