PHILADELPHIA – Combining the immunomodulatory agent mycophenolate with the antifibrotic pirfenidone led to more rapid improvement and showed a trend to be more effective than mycophenolate mofetil alone for treating the signs and symptoms of scleroderma-related interstitial lung disease, but the combination therapy came with an increase in side effects, according to results from the Scleroderma Lung Study III.
Dinesh Khanna, MBBS, MSc, of the University of Michigan, Ann Arbor, presented the results at the annual meeting of the American College of Rheumatology. He noted some problems with the study – namely its small size, enrolling only 51 patients, about one-third of its original goal. But he also said it showed a potential signal for efficacy and that the study itself could serve as a “template” for future studies of combination mycophenolate mofetil (MMF) plus pirfenidone therapy for scleroderma-related interstitial lung disease (SSc-ILD).
“The pirfenidone patients had quite a bit more GI side effects and photosensitivity, and those are known side effects,” Dr. Khanna said in an interview. “So the combination therapy had more side effects but trends to higher efficacy.”
The design of SLS-III, a phase 2 clinical trial, was a challenge, Dr. Khanna explained. The goal was to enroll 150 SSc-ILD patients who hadn’t had any previous treatment for their disease. Finding those patients proved difficult. “In fact, if you look at the recent history, 70% of the patients with early diffuse scleroderma are on MMF,” he said in his presentation. Compounding low study enrollment was the intervening COVID-19 pandemic, he added.
Testing a faster-acting combination
Nonetheless, the trial managed to enroll 27 patients in the combination therapy group and 24 in the MMF-plus-placebo group and compared their outcomes over 18 months. Study dosing was 1,500 mg MMF twice daily and pirfenidone 801 mg three times daily, titrated to the tolerable dose.
Despite the study’s being underpowered, Dr. Khanna said, it still reported some notable outcomes that merit further investigation. “I think what was intriguing in the study was the long-term benefit in the patient-reported outcomes and the structural changes,” he said in the interview.
Among those notable outcomes was a clinically significant change in forced vital capacity (FVC) percentage for the combination vs. the placebo groups: 2.24% vs. 2.09%. He also noted that the combination group saw a somewhat more robust improvement in FVC at six months: 2.59% (± 0.98%) vs. 0.92% (± 1.1%) in the placebo group.
The combination group showed greater improvements in high-resolution computed tomography-evaluated lung involvement and lung fibrosis and patient-reported outcomes, including a statistically significant 3.67-point greater improvement in PROMIS-29 physical function score (4.42 vs. 0.75).
The patients on combination therapy had higher rates of serious adverse events (SAEs), and seven discontinued one or both study drugs early, all in the combined arm. Four combination therapy patients had six SAEs, compared to two placebo patients with three SAEs. In the combination group, SAEs included chest pain, herpes zoster ophthalmicus, nodular basal cell cancer, marginal zone B cell lymphoma, renal crisis, and dyspnea. SAEs in the placebo group were colitis, COVID-19 and hypoxic respiratory failure.