Abrupt onset of severe parkinsonism in a patient with metastatic gastrointestinal stromal tumor receiving treatment with avapritinib: A case report.

Gastrointestinal stromal tumors (GISTs) are tumors of the digestive tract. To date, there have been no neurological paraneoplastic syndromes or symptoms associated with metastatic GISTs. Tyrosine kinase inhibitors (TKIs) are the typical class of agents used in management of this malignancy. Avapritinib, a new TKI, has been associated with myriad neurological adverse events with fairly rapid resolution in clinical trials. Herein, we present the case of a patient with metastatic GIST who, after starting treatment with avapritinib, developed rapidly progressive and persisting severe neuropsychiatric symptoms, including profound parkinsonism and encephalopathy, while concurrently receiving therapy with the antipsychotic olanzapine. We posit that the patient could be conceptualized as having a relative vulnerability to medication effects in the setting of metastatic GIST - possibly driven by an immune-mediated process - and that the addition of avapritinib triggered an overtly evident, clinically significant cascade of neurological deterioration.

An Intradermal Inoculation Mouse Model for Immunological Investigations of Acute Scrub Typhus and Persistent Infection.

Scrub typhus is a neglected tropical disease, caused by Orientia tsutsugamushi, a Gram-negative bacterium that is transmitted to mammalian hosts during feeding by Leptotrombidium mites and replicates predominantly within endothelial cells. Most studies of scrub typhus in animal models have utilized either intraperitoneal or intravenous inoculation; however, there is limited information on infection by the natural route in murine model skin or its related early host responses. Here, we developed an intradermal (i.d.) inoculation model of scrub typhus and focused on the kinetics of the host responses in the blood and major infected organs. Following ear inoculation with 6 x 104 O. tsutsugamushi, mice developed fever at 11-12 days post-infection (dpi), followed by marked hypothermia and body weight loss at 14-19 dpi. Bacteria in blood and tissues and histopathological changes were detected around 9 dpi and peaked around 14 dpi. Serum cytokine analyses revealed a mixed Th1/Th2 response, with marked elevations of MCP-1/CCL2, MIP-1α/CCL3 and IL-10 at 9 dpi, followed by increased concentrations of pro-inflammatory markers (IL-6, IL-12, IFN-γ, G-CSF, RANTES/CCL5, KC/CCL11, IL-1α/ß, IL-2, TNF-α, GM-CSF), as well as modulatory cytokines (IL-9, IL-13). Cytokine levels in lungs had similar elevation patterns, except for a marked reduction of IL-9. The Orientia 47-kDa gene and infectious bacteria were detected in several organs for up to 84 dpi, indicating persistent infection. This is the first comprehensive report of acute scrub typhus and persistent infection in i.d.-inoculated C57BL/6 mice. This is a significant improvement over current murine models for Orientia infection and will permit detailed studies of host immune responses and infection control interventions.