– A flurry of recent impressive studies of adalimumab for psoriasis provides welcome reassurance regarding the biologic agent’s long-term safety in real-world clinical practice, identifies a simple biomarker predictive of the likelihood of a favorable PASI 75 response, and highlights a disconnect in psoriatic arthritis (PsA) patients between clinical response as reflected in disease activity and radiographic progression of joint disease, according to Kristina C. Duffin, MD.

Dr. Kristina C. Duffin, University of Utah, Salt Lake Cith Bruce Jancin/MDedge News

Dr. Kristina C. Duffin

Also, a new citrate-free version of adalimumab (Humira) is available. It requires a new prescription, and an additional prior authorization is mandated by some insurers. But this is a welcome innovation for patients bothered by significant burning and stinging with their injections of classic adalimumab, Dr. Duffin, cochair of the department of dermatology at the University of Utah, Salt Lake City, said at the Hawaii Dermatology Seminar provided by Global Academy for Medical Education/Skin Disease Education Foundation.

New long-term safety data

Adalimumab is a market leader in biologic therapy for psoriasis. But the long-term experience with biologics in dermatology is still relatively limited, so the recent publication of two large studies providing encouraging evidence of the long-term safety of adalimumab is noteworthy.

Craig L. Leonardi, MD, of Saint Louis University, St. Louis, Mo., was first author of an analysis of long-term safety data from 18 clinical trials in adults with moderate to severe plaque psoriasis. The key takeaway, in Dr. Duffin’s view, was that the rate of adverse events, including serious infections and malignancies other than nonmelanoma skin cancer, remained stable over time out to 240 weeks of follow-up in patients on continuous treatment, with no new safety signals emerging (Br J Dermatol. 2019 Jan;180[1]:76-85).

However, randomized clinical trials often paint an overly rosy safety picture because of their strict inclusion and exclusion criteria.

“We single out patients for clinical trials because they’re especially healthy. That doesn’t happen in real-world registries,” she noted.

That’s why a systematic review of adalimumab’s safety performance in 10 real-world registries of adalimumab-treated psoriasis patients is particularly informative. The registries included in the systematic review, led by Bruce E. Strober, MD, PhD, professor of dermatology at the University of Connecticut, Farmington, didn’t all measure the same outcomes. But the three registries that documented major adverse cardiovascular events showed rates of less than 0.1 to less than 1 per 100 patient-years. Rates of malignancies other than nonmelanoma skin cancer were consistently in the 0.3-0.6 events per 100 patient-years range, similar to what has been reported in studies of other systemic psoriasis therapies, biologic as well as nonbiologic (J Eur Acad Dermatol Venereol. 2018 Dec;32[12]:2126-33).

Overall infection rates reported in the real-world registries ranged from 7.7 to 14.7 events per 100 patient-years, which is actually considerably lower than in the clinical trials. Rates of serious infections ranged from less than one up to two events per 100 patient-years, with the most common ones being cellulitis and pneumonia, consistent with the randomized trial experience.

Predicting response to adalimumab

A prospective, multicenter, observational cohort study of 544 psoriasis patients on adalimumab monotherapy conducted by U.K. investigators concluded that a patient’s serum drug level is the single most important predictor of treatment response. A cut point of 3.2 mcg/mL, which is considered the minimal effective circulating drug level, was associated with a 65% probability of a 75% improvement in Psoriasis Area and Severity Index from baseline, or PASI 75 response. The higher the serum drug level, the greater the likelihood of a PASI 75 response, up to a serum level of 7 mcg/mL, which was associated with an 81% probability of achieving PASI 75. Beyond 7 mcg/mL, however, the relationship with treatment response plateaued. Importantly, drug levels measured early on – at 1-12 weeks into therapy – were predictive of response 6 months later. So were steady-state levels (J Invest Dermatol. 2019 Jan;139[1]:115-23).

This is clinically useful information, Dr. Duffin observed.

“I’m hoping we’re going to see more real-world use of checking drug levels,” she said.

Indeed, even though the approved dosing of adalimumab for psoriasis is 40 mg by subcutaneous injection every 2 weeks, the new American Academy of Dermatology/National Psoriasis Foundation joint guidelines for treatment of psoriasis with biologics declare that “a maintenance dose of adalimumab at 40 mg/week is recommended for better disease control in some patients” (J Am Acad Dermatol. 2019 Feb 7. doi: 10.1016/j.jaad.2018.11.057. [Epub ahead of print]).

The new guidelines provide support for dermatologists who decide weekly therapy is best for a given patient, and adalimumab drug levels could prove useful in identifying the patient subgroup likely to benefit.

Dr. Duffin is often consulted by other physicians as to whether they should check for neutralizing antibodies in patients who appear to be losing therapeutic efficacy on a given biologic. She’s not a fan of the practice.

“There are commercial assays out there, but it’s very hard to interpret them because we don’t really know if they’re truly measuring neutralizing antibodies. And the cost is not insignificant; it can be hundreds of dollars,” she noted.

She believes a straightforward measurement of the serum biologic level is a better strategy.

“It makes sense: This is an indirect way of determining if there’s been neutralization of the drug, rather than trying to check the antibody that’s doing it, which is fraught with problems,” Dr. Duffin said.

Radiographic progression and clinical PsA activity on adalimumab don’t always correlate

A post hoc analysis of the randomized, double-blind, placebo-controlled ADEPT trial in PsA patients demonstrated that inhibition of radiographic progression as measured by change in modified total Sharp score from baseline through 24 weeks of adalimumab therapy was greater than expected based upon control of clinical disease activity (Rheumatology [Oxford]. 2019 Jan 3. doi: 10.1093/rheumatology/key417. [Epub ahead of print]).

One implication of the disconnect between radiographic progression and clinical disease documented in this study is that a dermatologist shouldn’t be too quick to change from adalimumab to another biologic just because a patient with PsA reports continued but bearable joint pain. And the converse is also true.

“I think that we as dermatologists probably shouldn’t be reassured when a patient says, ‘My joints feel great!” That’s because you may not necessarily be able to predict lack of progression in Sharp score based upon clinical response,” Dr. Duffin cautioned. “I think you should still have a rheumatologist check in with the patient and do x-rays periodically. The rheumatologist I work with does that, usually about on a yearly basis.”

Another key finding in the ADEPT analysis was that concomitant methotrexate had no added effect in terms of preventing joint destruction. This underscores the prescience of the first-ever collaborative American College of Rheumatology/National Psoriasis Foundation guidelines for the treatment of PsA (Arthritis Care Res (Hoboken). 2019 Jan;71[1]:2-29).

The new guidelines recommend that, in a psoriasis patient with confirmed PsA, the first-line treatment is a tumor necrosis factor (TNF) inhibitor. Agents from this class are preferred over other biologics because they are backed by a larger body of data regarding inhibition of joint disease progression. If the patient fails on the first TNF inhibitor prescribed, second-line therapy is another TNF inhibitor. So is third-line therapy.

Adalimumab citrate free

Not only does this new iteration of adalimumab do away with citrate as a buffer because it can cause pain and burning, it also utilizes a thinner 29-gauge needle rather than the standard 27-gauge. And the needle cover isn’t made with natural rubber latex. Also, both the pen and prefilled syringe contain half the volume of liquid, compared with the classic version of the biologic, so it’s 40 mg of drug in 0.4 mL rather than in 0.8 mL.

The packaging of adalimumab citrate free is different. It comes in a blue box to distinguish the product from the classic version.

Dr. Duffin reported receiving research grants from and serving as a consultant to AbbVie, which markets adalimumab, as well as close to a dozen other pharmaceutical companies.

The SDEF/Global Academy for Medical Education and this news organization are owned by the same parent company.