EXPERT ANALYSIS FROM AIBD 2016
ORLANDO (FRONTLINE MEDICAL NEWS) – Preclinical studies and years of clinical experience using the monoclonal antibody ustekinumab (Stelara, Janssen Biotech) in psoriasis and psoriatic arthritis offer important clues to any gastroenterologist perplexed by the official Food and Drug Administration indication, dosing frequency, and intensity for Crohn’s disease. Phase II and phase III findings also reveal where the monoclonal antibody may offer particular advantages, compared with other agents.
“Ustekinumab landed in your lap in September. You’re probably all trying to figure out how to get the ID formulation paid for with insurance,” William J. Sanborn, MD, professor and chief of the division of gastroenterology at the University of California, San Diego, said at the Advances in Inflammatory Bowel Diseases meeting. “But this is now the reality that you have this in your Crohn’s practice.”
The FDA approved ustekinumab to treat adults with moderately to severely active Crohn’s disease who 1) failed or were intolerant to immune modulators or corticosteroids but did not fail tumor necrosis factor (TNF) blockers or 2) failed or were intolerant to one or more TNF blockers. Dr. Sanborn and colleagues observed a significant induction of clinical response in a subgroup of patients who previously failed a TNF blocker in an early efficacy study ( Gastroenterology. 2008;135:1130-41 ). “This is where the idea of initially focusing on TNF failures came from,” he added at the meeting sponsored by the Crohn’s & Colitis Foundation of America.
Induction dosing in Crohn’s disease is intravenous versus subcutaneous in psoriasis and psoriatic arthritis, in part because of the same study. “It looked like relatively better bioavailability and relatively better effect with intravenous dosing,” Dr. Sanborn said. “In Crohn’s disease, it’s a completely different animal.”
Official induction dosing is approximately 6 mg/kg in three fixed doses according to patient weight in Crohn’s disease. The 6-mg/kg dose yielded the most consistent response, compared with 1-mg/kg or 3-mg/kg doses in a subsequent phase IIb study ( N Engl J Med. 2012;367:1519-28 ).
The most consistent induction results at weeks 6 and 8 were observed with 6 mg/kg ustekinumab versus 1 mg/kg or 3 mg/kg.
Dr. Sanborn and coinvestigators also saw “numeric differences in drug versus placebo for remission at 6 and 8 weeks “but it was not that clear from the phase II trial what the remission efficacy was, so that needed more exploration to really understand.”
Another distinction for ustekinumab in Crohn’s disease is the approved maintenance dosing of 90 mg subcutaneously every 8 weeks versus a 12-week interval recommended for psoriasis. “Why so much more in Crohn’s disease, and is that necessary?” Dr. Sanborn asked.
Based on changes in C-reactive protein levels and a “rapid drop” in Crohn’s Disease Activity Index scores by 4 weeks, “clearly efficacy was there for induction,” he said. Ustekinumab has a “quick onset – analogous to the TNF blockers.”
“These were quite encouraging data, and paved the way to move on to phase III [studies],” Dr. Sanborn said. The preclinical studies up to this point focused on patients with Crohn’s disease who previously failed TNF blockers. However, “in clinical practice, we would be interested to know if it would work in anti-TNF naive or nonfailures as well.”
So two subsequent studies assessed safety and efficacy in a TNF blocker–failure population (UNITI-1 trial. Inflamm. Bowel Dis. 2016 Mar;22 Suppl 1:S1 ) and a non-TNF failure population of patients who did fail previous conventional therapy such as steroids or immunomodulators ( UNITI-2 trial).
Clinical response and remission steadily rose following induction up to a significant difference versus placebo at 8 weeks in the non–TNF failure population. “Remember, in the phase IIa study, the remission rates were not as clear-cut, so this really nails down this as a good drug in both patient populations,” Dr. Sanborn said.
To evaluate long-term maintenance, investigators rerandomized all participants in the UNITI-1 and UNITI-2 studies. They saw a 15% gain in clinical remission out to week 44, compared with placebo. Dr. Sanborn noted that ustekinumab has a relatively long half-life, so the difference in patients switched to placebo may not have been as striking. “In practice it’s important to know the on-time and off-time of this agent, and I think the clinical trials make that clear.”
The trials also show that 12-week dosing works, Dr. Sanborn said. “You see about 20% gain for every 8-week dosing. You get extra 5% or 10% extra on all outcome measures at 8 weeks, compared to 12 weeks dosing, with no difference in safety signals.” He added, “So more intensive dosing of 90 mg every 8 weeks is what ended up getting approved in the United States.”
So what does all the preclinical evidence suggest about safety of ustekinumab? The UNITI trials combined included more than 1,000 patients, and there were no deaths, Dr. Sanborn said. “Usually with TNF blockers in 1,000 patients you would see a few deaths.”
Patient withdrawals from the preclinical studies were also relatively low, Dr. Sanborn reported. “With ustekinumab monotherapy, drug withdrawal is only 3% or 4%, so it seems to be different from TNF blockers in that sense [too].”
In addition, the rates of adverse events were similar between placebo (83.5%) and ustekinumab’s combined every 8 week and every 12 week dosing groups through 44 weeks (81.0%), Dr. Sanborn said. The rates of serious adverse events were likewise similar, 15.0% and 11.0%, respectively. Reported malignancy included two cases of basal cell skin cancers, one in the placebo group and one in the every-8-week dosing group, he added.
“So all those black box warnings you’re used to worrying about with TNF blockers – serious infections, about opportunistic infections, malignancy – there is no black box warning with this agent around that.”
Dr. Sanborn noted that the FDA labeling reports infections. “We know Crohn’s disease patients are [also] getting azathioprine, steroids, methotrexate, so you will see some infections, but there wasn’t a consistent opportunistic infection signal.”
One case of reversible posterior leukoencephalopathy syndrome is included on the labeling. Dr. Sanborn also put this in perspective: “With all the experience in psoriasis and psoriatic arthritis, and the clinical trials [in IBD], there is just one case. So the relationship is not very clear.”
“The safety signals with ustekinumab are really very good. It seems to be an extremely safe agent – we really don’t see much in terms of infections,” Brian Feagan, MD, an internist and gastroenterologist at the University of Western Ontario in London, said in a separate presentation at the conference. “We don’t have a lot of long-term experience with ustekinumab in Crohn’s disease, but we have a lot of experience in psoriasis, and it’s a safe drug.”
“Ustekinumab may be our first really valid monotherapy, with less immunogenicity,” Dr. Feagan said.