Surgical Management in Herpes Simplex Encephalitis: Illustrative Case Report and Systematic Review of the Literature

BACKGROUND

Herpes simplex virus (HSV) is a common cause of viral encephalitis and can result in refractory seizures. Although HSV encephalitis (HSVE) is treated primarily with acyclovir, surgery can play a role in medically intractable cases.

OBJECTIVE

To systematically review cases describing surgery for the treatment of severe HSVE. We also present an illustrative case of anterior temporal lobectomy (ATL) for refractory status epilepticus in a patient with unilateral HSVE. This case demonstrates one clinical context in which surgery can be a useful adjunct.

METHODS

We performed a systematic review using PubMed and Google Scholar, including case reports and series describing surgical interventions for HSVE. Clinical data were extracted from 54 publications that incorporated 67 patient cases.

RESULTS

Surgical decompression occurred at a wide range of times after the onset of illness, although most patients were operated on 4 or more days after HSVE symptoms began. Numerous reports indicated that decompressive craniectomy, temporal lobectomy, and hematoma removal could treat intractably elevated intracranial pressure because of HSVE with favorable long-term outcomes. We describe an additional case in which a 52-year-old woman with HSVE developed refractory right temporal lobe seizures. After ATL, the seizures resolved with significant clinical improvement.

CONCLUSION

Surgical treatment can be a useful adjunct for treatment of HSVE. There is substantial variability in the timing of surgical decompression in patients with HSVE, which can be necessary up to approximately 3 weeks after illness onset. ATL should be considered for refractory status epilepticus in HSVE with a unilateral seizure focus.

The Clinical Landscape of Cell-Free DNA Alterations in 1,671 Patients with Advanced Biliary Tract Cancer

BACKGROUND

Targeted therapies have transformed clinical management of advanced biliary tract cancer (BTC). Cell-free DNA (cfDNA) analysis is an attractive approach for cancer genomic profiling that overcomes many limitations of traditional tissue-based analysis. We examined cfDNA as a tool to inform clinical management of patients with advanced BTC and generate novel insights into BTC tumor biology.

PATIENTS AND METHODS

We analyzed next-generation sequencing data of 2,068 cfDNA samples from 1,671 patients with advanced BTC generated with Guardant360. We performed clinical annotation on a multi-institutional subset (n=225) to assess intra-patient cfDNA-tumor concordance and the association of cfDNA variant allele fraction (VAF) with clinical outcomes.

RESULTS

Genetic alterations were detected in cfDNA in 84% of patients, with targetable alterations detected in 44% of patients. FGFR2 fusions, IDH1 mutations, and BRAF V600E were clonal in majority of cases, affirming these targetable alterations as early driver events in BTC. Concordance between cfDNA and tissue for mutation detection was high for IDH1 mutations (87%) and BRAF V600E (100%), and low for FGFR2 fusions (18%). cfDNA analysis uncovered novel putative mechanisms of resistance to targeted therapies, including mutation of the cysteine residue (FGFR2 C492F) to which covalent FGFR inhibitors bind. High pre-treatment cfDNA VAF associated with poor prognosis and shorter response to chemotherapy and targeted therapy. Finally, we report the frequency of promising targets in advanced BTC currently under investigation in other advanced solid tumors, including KRAS G12C (1.0%), KRAS G12D (5.1%), PIK3CA mutations (6.8%), and ERBB2 amplifications (4.9%).

CONCLUSIONS

These findings from the largest and most comprehensive study to date of cfDNA from patients with advanced BTC highlight the utility of cfDNA analysis in current management of this disease. Characterization of oncogenic drivers and mechanisms of therapeutic resistance in this study will inform drug development efforts to reduce mortality for patients with BTC.

Hemolysis Index and Potassium Reporting

OBJECTIVES

In vitro hemolysis generates a spurious increase in potassium. Roche Diagnostics recently revised its recommended guidelines for potassium reporting on cobas analyzers. By dramatically reducing the allowable degree of hemolysis, these guidelines would increase specimen rejection rates. We attempted to balance the desire to avoid inaccurate results with the clinical implications of increased specimen rejection rates.

METHODS

We downloaded hemolytic indices (HI) for 80,795 specimens tested at our institution on cobas chemistry analyzers in 1 month and evaluated potential specimen rejection rates based on the new criteria. We also spiked nonhemolyzed samples with hemolyzed blood to assess the influence of HI values on potassium measurements.

RESULTS

The new recommendations would lead to specimen rejection rates of 76% in the neonatal intensive care unit (NICU), 41% in the emergency department (ED), 16% in inpatient specimens, and 9% in outpatient samples. Our current criteria of reporting potassium concentrations in inpatient and outpatient specimens with HI ≤100 and in NICU and ED specimens with HI ≤300 and additional interpretive guidance for HI values between 100 and 300 reduce unnecessary specimen rejections to 3% in NICU, 2% in ED and inpatients, and less than 1% in outpatients without significantly increasing the number of clinically consequential incorrect results.

CONCLUSIONS

The new recommendations would lead to unacceptably high specimen rejection rates. Laboratories should develop context-specific, evidence-based reporting criteria that minimize reporting of inaccurate results without disrupting delivery of care.

TH17 cells require ongoing classic IL-6 receptor signaling to retain transcriptional and functional identity

Acting in concert with TGF-β, interleukin-6 (IL-6) signaling induces T helper 17 (T_H17) cell development by programming T_H17-related genes via signal transducers and activators of transcription 3 (STAT3). A role for IL-6 signaling beyond the inductive phase of T_H17 cell development has not been defined because IL-23 signaling downstream of T_H17 cell induction also activates STAT3 and is thought responsible for T_H17 cell maintenance. Here, we find that IL-6 signaling is required for both induction and maintenance of mouse T_H17 cells; IL-6Rα-deficient T_H17 cells rapidly lost their T_H17 phenotype and did not cause disease in two models of colitis. Cotransfer of wild-type T_H17 cells with IL-6Rα-deficient T_H17 cells induced colitis but was unable to rescue phenotype loss of the latter. High IL-6 expression in the colon promoted classic, or cis, rather than transreceptor signaling that was required for maintenance of T_H17 cells. Thus, ongoing classic IL-6 signaling underpins the T_H17 program and is required for T_H17 cell maintenance and function.

IL2 production predicts Tfh differentiation

Naïve CD4 T cells differentiate into functionally distinct subsets in response to a set of extrinsic and intrinsic cues. Effector subsets, including Th1, Th2 and Th17 CD4s, are required for optimal cellular responses to invading pathogens, while class switched antibody responses depend on the differentiation of T follicular helper cells (Tfh). Development of both Tfh and non-Tfh occurs in parallel and involves two distinct but functionally related expression bifurcations. Upon formation of T cell receptor (TCR)/major histocompatibility (MHC) synapses with antigen-presenting cells (APC), a discrete subset of activated T cells secretes the cytokine IL2. Similarly, a portion of activated cells express the transcription factor Bcl6 and differentiate into Tfh cells, while the remainder express Blimp1 and develop into effector CD4s. However, the cellular, temporal and mechanistic relationships between these two bifurcations remain unclear. Here we show that the IL2 and Bcl6/Blimp1 expression bifurcations occur simultaneously, precede cell division, predict differentiation into Tfh and non-Tfh subsets, and are mechanistically related to antigen availability TCR density.