Inclusion body myositis in a patient with chronic myeloid leukemia treated with dasatinib: a case report

INTRODUCTION Chronic myelogenous leukemia is often treated using tyrosine kinase inhibitors such as dasatinib. Here we describe a rare case of inflammatory myopathy in a patient with chronic myelogenous leukemia treated with the tyrosine kinase inhibitor dasatinib. CASE PRESENTATION A 69-year-old Caucasian man with imatinib-resistant chronic myelogenous leukemia achieved complete molecular remission in response to dasatinib therapy. However, from a normal initial serum creatine kinase level, he developed elevated serum creatine kinase levels and gradual-onset progressive muscle weakness after dasatinib therapy was initiated. Our patient was eventually diagnosed with inclusion body myositis. However, we were unable to determine the mechanism underlying the dasatinib-associated muscle weakness. Given the efficacy of dasatinib in the treatment of chronic myelogenous leukemia and our patient's mild symptoms of inclusion body myositis, he continued to receive dasatinib under close clinical and laboratory observation. CONCLUSION Despite the wide use of dasatinib and its documented safety, we report a case of severe muscle injury of unknown etiology. Therefore, patients with chronic myelogenous leukemia receiving dasatinib and perhaps all tyrosine kinase inhibitors should be carefully monitored for signs of muscle injury, especially if this is associated with significant elevations in serum creatine kinase levels.