Opioid Use Disorder Injection Drug Gets FDA Priority

The US Food and Drug Administration (FDA) has approved a Priority Review Designation for once-monthly opioid use disorder (OUD) treatment RBP-6000, which will be considered for its new drug application (NDA) in late November.

The investigational treatment, an injectable buprenorphine for adult moderate-to-severe OUD patients, was submitted for NDA in May with major consideration to a phase 3 efficacy and safety study.

The study (RBP-US-13-0001) compared 2 different doses of the injection treatment versus placebo. Eligible OUD non-placebo patients received either 300 mg buprenorphine for 6 injections, or 300 mg for two injections followed by 100 mg buprenorphine for four injections, over a 6-month period. All participating patients were not on treatment for OUD at the time of the trial, and supplementally received counseling and psychosocial support during the treatment phase.

From week 5 through week 24, RBP-6000 reached the primary endpoint of the cumulative distribution function (CDF) of the percentage of urine samples negative for opioids, combined with self-reports negative for illicit opioid use collected, versus placebo.

The secondary endpoint — treatment success defined as any patient with at least 80% of urine samples negative for opioids, combined with self-reports negative for illicit opioid use in the same trial span — was also achieved in both dosage rates versus placebo.

Results were confirmed by exposure-response analyses demonstrating a relationship between active ingredient buprenorphine primary plasma concentrations, abstinence, withdrawal symptoms and opioid cravings, Ponni Subbiah, chief medical officer of producing pharmaceutical company Indivior, said.

These successful results were what put the study “at the core” of Indivior’s NDA submission of RBP-6000, Subbiah said. Supplementally, the discovery of being able to gauge efficacy with plasma concentrations has positive implications for further OUD researcher — regardless of RBP-6000’s FDA fate.

“We’re very excited about that,” Subbiah said. “It’s very science based. It’s not just throwing a dart and hoping treatment helps the patient.”

Christian Heidbreder, PhD, Inidivior chief scientific officer, said RBP-6000 would “represent an entirely new treatment paradigm” if approved by the FDA.

“We look forward to continuing to work closely with the Agency as they review our New Drug Application and bring this potential innovative treatment option to patients and physicians,” Heidbreder said.

Subbiah acknowledged the current state of opioid abuse as an epidemic, citing a 2015 study that found that almost 10 million Americans met the criteria for prescription medicine abuse. She called for adjustments to medicinal prescription rates, the pursuit of new treatment options, and a more clear interpretation of OUD.

“It’s a chronic disease, like diabetes, asthma or hypertension,” Subbiah said. “We know that when people who have a chronic disease relapse, that doesn’t mean they have failed in their treatment.”

Subbiah noted that similar to a diabetic “relapsing” by eating a sugary meal, OUD patients who relapse should only be provided more education and information.

RBP-6000 would be considered a part of a combination therapy, along with counseling and psychosocial support. As a once-monthly treatment administered by healthcare professionals, it could simultaneously address OUD treatment frequency issues and limit opportunities of drug abuse, Subbiah said.

As researchers work towards patient optimization for this wide-scale condition, Subbiah emphasized the role RBP-6000 could play.

“What we have been advocating for is a multi-form approach,” Subbiah said. “We have new options coming in. It’s always important we look for new treatment options.”

A press release regarding the study was made available.

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