Get ready for cancer immunotherapy-induced rheumatic diseases

Rheumatologic IRAEs are seriously underdiagnosed

Back in the pre-ICI days, Dr. Bingham was coauthor of a major study which concluded that clinical trialists in oncology consistently downgrade the severity of rheumatologic adverse events, often by 1 or 2 grades (J Rheumatol. 2007 Jun;34[6]:1401-14).

Unpublished details of ICI clinical trials in melanoma that he obtained from Bristol-Myers Squibb suggest that the true rate of rheumatologic IRAEs is about 20%, or roughly double that reported in the studies. That’s because the adverse events–grading system used in oncology undercalls the severity of arthritis and autoimmune disorders.

Indeed, the National Cancer Institute’s Common Terminology Criteria for Adverse Events, used in oncology clinical trials, is confusing on the topic of musculoskeletal and connective tissue disorders as treatment-emergent adverse events, according to Dr. Bingham. He noted that an oncologist can code a swollen joint in three different ways – joint effusion, arthritis, or arthralgia – and it takes disabling interference with self-care in activities of daily living for that swollen joint to rise to the level of a Grade 3 adverse event. From a rheumatology trialist’s perspective, that would be a Grade 4 disability.

Plus, neither the product labeling nor the patient information guides for the approved immunotherapy drugs mention the importance of monitoring for rheumatologic IRAEs or their management.

“There is poor awareness of musculoskeletal and rheumatic IRAEs in the general oncology community,” Dr. Bingham asserted. “But, if you talk with any oncology nurses who work in a clinical trial, they will tell you they’re seeing these events with significant frequency and severity.”
 

Treatment and response

It’s critical to gain control of rheumatologic IRAEs quickly so that patients can get on with their cancer immunotherapy. Dr. Bingham uses intra-articular steroid injections for patients with oligoarthritis and high-dose oral prednisone for polyarticular disease. He starts methotrexate and/or leflunomide early because the conventional disease-modifying antirheumatic drugs have roughly a 2-month delay in onset of action. He has had several patients who are unable to taper steroids despite background methotrexate.

In the most severely affected patients, he has turned to biologic agents in consultation with their oncologists. Tumor necrosis factor (TNF) inhibitors are the ones he and other rheumatologists have used most often.

“Notably, we have not been able to taper down very well. We have patients who are out more than 2 years now who still require their TNF inhibitor to treat their inflammatory arthritis, and these are patients on conventional disease–modifying antirheumatic drugs as well. As soon as it’s tapered, the arthritis begins to come back,” according to Dr. Bingham.

In marked contrast, colitis as an IRAE typically clears in response to just one or two doses of a TNF inhibitor.

One audience member related that she’d encountered a roadblock in trying to get authorization for a TNF inhibitor for a patient with a rheumatologic IRAE secondary to ICI treatment for metastatic melanoma because the labeling states these agents are relatively contraindicated in melanoma patients. Dr. Bingham offered a tip: Collaborate with the patient’s oncologist.

“In most cases, oncologists can get infliximab for these patients and administer it in their infusion centers. They are able to get things authorized with very little trouble,” he said.

Besides, most of these patients with severe inflammatory arthritis meet conventional criteria for TNF inhibitor therapy, based on their number of infected joints and elevated acute phase reactants for longer than 6 weeks, Dr. Bingham noted.

“We’ve had some very interesting conversations with patients. It’s impressive to see the impact arthritis can have on people. A lot of patients have said, ‘I don’t care if I die. Get me functional right now.’ That’s pretty profound. Quality of life is still very important for people, even when dealing with life-threatening diseases,” he observed.

Oncologists are actually eager for their patients to get on steroid-sparing therapy because of concern that high doses of steroids may reduce the efficacy of cancer immunotherapy. That’s not an issue with the TNF inhibitors, the rheumatologist continued.

Turning to the utility of other classes of biologic agents, Dr. Bingham advised avoiding abatacept (Orencia) because its mechanism of action is likely to cause interference with the cancer immunotherapy. Rituximab (Rituxan) takes too long to act. Anakinra (Kineret), tofacitinib (Xeljanz), and tocilizumab (Actemra), on the other hand, are agents he is interested in using as alternatives to TNF inhibitors, although he hasn’t done so yet.
 

Use of ICIs in patients with preexisting autoimmune disease

The experience here is entirely anecdotal, since such patients have been excluded from ICI clinical trials, but the available evidence suggests physicians should be prepared for higher rheumatologic IRAE rates in this setting. Investigators at Vanderbilt University reported that 8 of 30 cancer patients with known preexisting autoimmune disease experienced flares of that disease when treated with ipilimumab, and 10 developed a new IRAE (Therap Adv Gastroenterol. 2016 Jul;9[4]:457-62).