Visual Hallucinations and Myoclonus: Previously Unreported Neurotoxic Effects of Blinatumomab (P2.250)

Objective: To describe two unreported neurotoxic effects of blinatumomab. Background: Blinatumomab is a bispecific T-cell-engager that was granted accelerated approval by the FDA for use in Philadelphia chromosome-negative relapsed or refractory B-cell precursor acute lymphoblastic leukemia (ALL). During clinical trials, 225 patients underwent treatment with blinatumomab. Neurotoxicity was reported in about 50[percnt], with severe neurotoxicity in 13[percnt]. The cause of blinatumomab-induced neurotoxicity is not understood and was not predicted by pre-clinical studies. The most common neurological adverse effects were headache, tremor and dizziness. Other rare reactions included encephalopathy, paresthesia, aphasia/speech disorder, seizures, memory impairment and cognitive disorder. Hallucinations and myoclonus have not yet been reported. Methods: Case Report. Results: A 22-year-old male with a history of refractory B-cell precursor ALL initiated treatment with blinatumomab. He completed 7 days of the 9 mcg dose, given as a continuous infusion over 24 hours, after which the dose was increased to 28 mcg. Eight days into treatment, neurology was consulted for evaluation of possible neurotoxicity. On exam, the patient was found to be severely encephalopathic, had a coarse hand tremor, myoclonic jerking, as well as visual hallucinations. Labs and imaging were reviewed and were unremarkable. The blinatumomab infusion was discontinued. Treatment with dexamethasone and primidone was initiated, the latter agent primarily for the tremor. The patient’s clinical findings resolved within 72 hours. Conclusions: Novel anti-neoplastic agents may cause unexpected neurotoxicity. A significant proportion of blinatumomab-treated patients experience neurotoxicity. In addition to previously reported effects, visual hallucinations and myoclonus may be observed. With discontinuation of therapy and initiation of steroids, these neurotoxic effects are reversible. Disclosure: Dr. Bhangav has nothing to disclose. Dr. Schmalstieg has nothing to disclose.