Pembrolizumab in Platinum-Refractory or Relapsed Thymic Epithelial Tumors


Key Points

  • Pembrolizumab produced responses in both thymoma and thymic carcinoma.
  • Grade 3 or 4 immune-related adverse events were fairly common.

In a Korean single-center phase II study reported in the Journal of Clinical Oncology, Cho et al found that pembrolizumab (Keytruda) was active in advanced thymic epithelial tumors progressing after platinum-based chemotherapy.

Study Details

The study included 26 patients with thymic carcinoma and 7 with thymoma. Patients were excluded if they had an active autoimmune disease requiring systemic treatment within the past year or documented history of clinically severe autoimmune disease. Patients received pembrolizumab 200 mg every 3 weeks until tumor progression or unacceptable toxicity. Approximately 57% of patients had received ≥ 2 prior lines of therapy.

Among 7 patients with thymoma, 2 (28.6%) had partial response and 5 (71.6%) had stable disease; median duration of response was not reached. Of 26 patients with thymic carcinoma, 5 (19.2%) had partial response and 14 (53.8%) had stable disease; median duration of response was 9.7 months.

Median progression-free survival was 6.1 months in both groups. Median overall survival was not reached in thymoma patients and was 14.5 months for those with thymic carcinoma.

Adverse Events

The most common adverse events of any grade included dyspnea (33%), chest wall pain (30%), anorexia (21%), and fatigue (21%). Five patients with thymoma (71%) and 4 (15%) with thymic carcinoma had grade ≥ 3 immune-related adverse events, including hepatitis (12%), myocarditis (9%), myasthenia gravis (6%), thyroiditis (3%), antineutrophil cytoplasmic antibody–associated rapidly progressive glomerulonephritis (3%), colitis (3%), and subacute myoclonus (3%).

The investigators concluded, “Pembrolizumab showed encouraging antitumor activity in patients with advanced [thymic epithelial tumors]. Given the high incidence of autoimmunity, additional studies are needed to identify those who can benefit from pembrolizumab without immune-related adverse events.”

The study was supported by the Korea Health Industry Development Institute, funded by the Ministry of Health and Welfare, Republic of Korea.

Myung-Ju Ahn, MD, PhD, of the Samsung Medical Center, Sungkyunkwan University School of Medicine, is the corresponding author for the Journal of Clinical Oncology article.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.