The data from the trial also highlight the deficiencies of sedimentation rate and C-reactive protein (CRP) in assessing disease activity, Dr. Stone said. A third of the flares across both prednisone groups happened in those with a normal CRP.
“We tend to use these acute phase reactant measurements as a crutch, and I think these data underscore very pointedly how bad a crutch that is to use,” he said.
This reinforces the idea that GCA, and GCA flares, are clinical diagnoses.
“We will continue to look for the optimal imaging study and approach to diagnosing disease flare,” he said. “But for quite a while to come, I am sure clinical judgment is going to remain very important in taking care of patients with this disease.”
‘I would really aim to get patients off steroids completely in four months or so.’ —Dr. Stone
Quality of Life
Another striking finding from the trial was in the quality-of-life data. Improvements among patients receiving tocilizumab brought their quality-of-life measurements to levels that surpassed normative values for age- and gender-matched patients.
“I’ve never seen quality-of-life data like these,” Dr. Stone said. He mentioned these surprising improvements may have to do with the role IL-6 seems to play in depression.
Patients in the tocilizumab groups were also less likely to have serious adverse events.
As he discussed messages to be gleaned from the GIACTA data, Dr. Stone discussed the patient whose progress on tocilizumab prompted the trial. The 58-year-old man was started on prednisone, with a plan to taper over six months. He flared when the prednisone was stopped. Then he was started on tocilizumab.
At one year, Dr. Stone chose to stop the drug. “He was feeling great. He had been off prednisone for many months. He said, ‘Do I really have to continue to inject this stuff every week?’ I said, ‘Well, we should stop it and see what happens.’” His CRP and ESR are measured every month or two, and have remained low. He’s been in remission for a year since stopping tocilizumab.
Many questions remain for managing GCA patients on tocilizumab. For one thing, how should their disease activity be assessed over time?
“I think we overuse imaging in these patients,” Dr. Stone said. “I think the key will be understanding how he is feeling. His clinical symptomatology and his acute phase reactants, which are simple and easy to measure, will also be crucial.”