Prepare for deluge of JAK inhibitors for RA
REPORTING FROM RWCS 2019
Other advantages of JAK inhibitors
Speed of onset is another advantage in addition to oral administration and efficacy greater than or equivalent to anti-TNF therapy, according to Dr. Genovese.
“As a class, JAK inhibitors have a faster onset than methotrexate in terms of improvement in disease activity and pain. So in a few weeks you can have a sense of whether folks are going to be responders,” the rheumatologist said.
Does JAK isoform selectivity really make a difference in terms of efficacy and safety?
It’s doubtful, the rheumatologists agreed. All of these oral small molecules target JAK1, and that’s what’s key.
Tofacitinib is relatively selective for JAK1 and JAK3, baricitinib for JAK1 and JAK2, upadacitinib and fibotinib for JAK1, and peficitinib is a pan-JAK inhibitor.
What are the safety concerns with this class of medications?
The risk of herpes zoster is higher than with TNF inhibitors, reinforcing the importance of varicella vaccination in JAK inhibitor candidates. Anemia occurs in a small percentage of patients. As for the risk of venous thromboembolism as a potential side effect of JAK inhibitors, a topic of great concern to the FDA, Dr. Fleischmann dismissed it as vastly overblown.
“I think VTEs are an RA effect. You see it with all the drugs, including methotrexate,” he said.
Idiosyncratic self-limited increases in creatine kinase have been seen in 2%-4% of patients on JAK inhibitors in pretty much all of the clinical trials. “I’m not aware of any cases of myositis, though,” Dr. Fleischmann noted.
As for the teratogenicity potential of JAK inhibitors, Dr. Genovese said that, as is true for most medications, it hasn’t been well studied.
“We don’t know. But I would not choose to use a JAK inhibitor in a woman who is going to conceive, has conceived, or is breastfeeding. I just don’t think that would be a good decision,” according to the rheumatologist.
Which JAK inhibitor is the best choice for treatment of RA?
It’s impossible to say because of the hazards in trying to draw meaningful conclusions from cross-study comparisons, the experts agreed.
“It’s a challenge. I think at the end of the day there will probably be one agent that looks like it might be best in class predicated on having the most number of indications, and that will probably become a preferred agent. The question is, does that happen before tofacitinib goes generic? And I don’t know the answer to that,” Dr. Genovese said.
Notably, upadacitinib is the subject of a plethora of ongoing phase 3 trials in atopic dermatitis, psoriatic arthritis, Crohn’s disease, and ulcerative colitis. It is also in earlier-phase investigation for the treatment of ankylosing spondylitis.
Do we really need all these JAK inhibitors?
“How many TNF inhibitors do you need?” Dr. Genovese retorted. “I think the reality is there’s probably a finite number and additional members add to the class, but there probably will always be one or two that are going to be best in class.”
Both rheumatologists indicated they serve as consultants to more than a dozen pharmaceutical companies and receive research grants from numerous firms.
