First IgG4-Related Disease Guidelines Presented

Marcia Frellick

October 24, 2018

CHICAGO — Classification criteria for IgG4-related disease, the first criteria drafted for the recently recognized condition, were presented during a press conference here at the American College of Rheumatology (ACR) 2018 Annual Meeting.

The very treatable disease "tends to present with mass lesions," and is often mistaken for pancreatic cancer, another cancer, or Sjögren's syndrome — with severe consequences, said John Stone, MD, from Harvard Medical School and Massachusetts General Hospital in Boston.

John Stone presenting at ACR 2018. (Source: Darbe Rotach, Medscape)

Stone himself has seen nearly 20 patients who have undergone a modified Whipple procedure because they were mistakenly diagnosed with pancreatic cancer.

"You've never seen a happier patient than one who wakes up after a modified Whipple procedure and is told they don't have cancer," he reported. However, "they have diabetes and pancreatic insufficiency as a result of the surgery. The same is true for renal cancers and a variety of lymphomas that commonly mimic IgG4-related disease. So recognition of this is really, really important."

Recognition of this is really, really important.

IgG4-related disease has only been widely recognized in the past 10 years, and it is estimated that 180,000 people are affected in the United States.

"Every organ in the body has been described as possibly being affected by what we now call IgG4-related disease," Stone said.

The classification guidelines, which were developed by 79 experts from five continents, are awaiting approval by ACR and the European League Against Rheumatism (EULAR).

The guidelines will help rheumatologists be aware, for instance, that granulomatosis with polyangiitis is a very good mimicker of IgG4-related disease but the treatment and clinical considerations are different, Stone said.

According to the guidelines, to arrive at a diagnosis of IgG4-related disease, physicians must integrate clinical findings, bloodwork, radiologic findings, and any pathology.

"Any one of those alone is insufficient," he explained.

A patient has to have manifestation in one of 10 organs and must meet the exclusion criteria for other mimickers and the inclusion criteria. There are no separate diagnostic criteria for IgG4-related disease because the cause is not yet known.

"We've made a remarkable amount of progress in a short time, and recently have identified a couple of antigens that might trigger it. But it's really not possible to say there are diagnostic criteria for a disease that you don't know the cause of," said Stone.

However, "the classification criteria are, I believe, very good and will — as the high sensitivity and specificity indicate -— be a good way of getting most of the patients, and the right patients, into clinical study," he noted.

As drafted, the classification criteria have a sensitivity for this diagnosis of 85.5% and a specificity of 99.2%.

"We are preparing to do the first multicenter, international clinical trials, so the timing of the ACR–EULAR validated classification criteria for this disease is really perfect," he added.

Christopher Mecoli moderating the press conference at ACR 2018. (Source: Darbe Rotach, Medscape)

"It's often hard to tease out what the true diagnosis is," said Christopher Mecoli, MD, from Johns Hopkins School of Medicine in Baltimore, who moderated the press conference and who has seen these patients in his practice.

"I think it's a step in the right direction," he told Medscape Medical News. "We need classification criteria for clinical trial design. They are integral for developing a well thought-out clinical trial. In using them, you'll be able to have a better study and a higher likelihood of meeting the primary end point, whether that's looking at a new drug or a treatment outcome."

Stone and Mecoli have disclosed no relevant financial relationships.

American College of Rheumatology (ACR) 2018 Annual Meeting. Presented October 24, 2018.

Follow Medscape Rheumatology on Twitter @MedscapeRheum and Marcia Frellick @mfrellick

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