Immune Checkpoint Inhibitor-Induced Guillain Barre Syndrome: A Single-Institution Case Report and Narrative Review.

Guillain-Barré syndrome (GBS) resulting from the use of immune checkpoint inhibitors (ICIs) is relatively uncommon but has been reported. Herein, we discuss a case of a 67-year-old patient who received neoadjuvant ICI for treatment of non-small cell lung cancer and then presented with lower extremity weakness and areflexia, progressing to respiratory muscle and upper extremity weakness. Given the increasing use of ICI in cancer management, awareness of neurological autoimmune side effects is essential. ICI-mediated GBS can be severe and fatal if not diagnosed promptly. We discuss a case of ICI-induced GBS and review literature on current management approaches.

Microcystic/reticular Schwannoma: morphological features causing diagnostic dilemma on fine-needle aspiration cytology.

BACKGROUND: Schwannoma is a common, benign, peripheral nerve sheath tumor. Fine-needle aspiration (FNA) has been very useful for diagnosing classic Schwannoma. Recently, a new morphological variant, the so-called microcystic/reticular Schwannoma, has been recognized. Although histological features of microcystic/reticular Schwannoma have been described, there are no available reports on its FNA cytological appearance. CASE REPORT: A 28-year-old male presented with right arm and finger tingling and numbness. Physical examination found a right lower neck mass. He underwent FNA, followed by needle core biopsy. A diagnosis of microcystic/reticular schwannoma was made. In this case report, we focused on the FNA diagnostic features, thoroughly searched the literature, and discussed relevant information for differential diagnosis. CONCLUSIONS: Unlike classic Schwannoma, microcystic/reticular variant has unique cytological features which can mimic those of several morphologically similar mass lesions, making the FNA interpretation more challenging. Cytopathologists should be aware of this new variant of Schwannoma when evaluating FNA cytology of mass lesions showing low-grade, paucicellular, and myxoid features.

Signal transducer and activator of transcription 3 mutation with invasive eosinophilic disease.

Hyper-IgE syndrome (HIES), or Jobs disease, is a rare immunologic disorder characterized by the triad of staphylococcal abscesses, pneumonia with pneumatocele formation, and elevated IgE. It has been shown to have multiple modes of inheritance, autosomal dominant being more common than autosomal recessive, with sporadic cases as well. A mutation in signal transducer and activator of transcription 3 (STAT3) gene has been linked to the development of the sporadic and dominant forms of HIES. Peripheral eosinophilia, typically greater than two standard deviations from the normal population, is often seen in association with HIES. Despite these elevated levels of blood eosinophils, there have been no reported cases of invasive eosinophilic disease, such as eosonophilic esophagitic. Here we report the first description, to our knowledge, of a patient with HIES with a STAT3 mutation involving exon 12, Thr389Ile, and invasive eosinophilic disease of the esophagus. STAT3 modulates the expression of several genes that control central cell processes such as growth and death in response to external soluble stimuli. A mutation in the STAT3 molecule may affect the eosinophil's response to IL-5 and thus reduce the chemotaxic ability of those cells to migrate into tissues. This may then explain the paucity of eosinophilic infiltrative disease in patients with STAT3 mutations. The level of eosinophilic involvement may be related to the site or type of mutation within the STAT3 molecule. As more data are collected, we may be able to assess whether certain mutations dictate different clinical outcomes, which could prove helpful in directing therapy.

MET-independent lung cancer cells evading EGFR kinase inhibitors are therapeutically susceptible to BH3 mimetic agents.

Targeted therapies for cancer are inherently limited by the inevitable recurrence of resistant disease after initial responses. To define early molecular changes within residual tumor cells that persist after treatment, we analyzed drug-sensitive lung adenocarcinoma cell lines exposed to reversible or irreversible epidermal growth factor receptor (EGFR) inhibitors, alone or in combination with MET-kinase inhibitors, to characterize the adaptive response that engenders drug resistance. Tumor cells displaying early resistance exhibited dependence on MET-independent activation of BCL-2/BCL-XL survival signaling. Further, such cells displayed a quiescence-like state associated with greatly retarded cell proliferation and cytoskeletal functions that were readily reversed after withdrawal of targeted inhibitors. Findings were validated in a xenograft model, showing BCL-2 induction and p-STAT3[Y705] activation within the residual tumor cells surviving the initial antitumor response to targeted therapies. Disrupting the mitochondrial BCL-2/BCL-XL antiapoptotic machinery in early survivor cells using BCL-2 Homology Domain 3 (BH3) mimetic agents such as ABT-737, or by dual RNAi-mediated knockdown of BCL-2/BCL-XL, was sufficient to eradicate the early-resistant lung-tumor-cells evading targeted inhibitors. Similarly, in a xenograft model the preemptive cotreatment of lung tumor cells with an EGFR inhibitor and a BH3 mimetic eradicated early TKI-resistant evaders and ultimately achieved a more durable response with prolonged remission. Our findings prompt prospective clinical investigations using BH3-mimetics combined with targeted receptor kinase inhibitors to optimize and improve clinical outcomes in lung-cancer treatment.