Polymorphic ventricular tachycardia and cardiac arrest from abiraterone-induced hypokalemia: a case report

BACKGROUND

Polymorphic ventricular tachycardia (PMVT) is an unstable and often fatal cardiac tachyarrhythmia. While there are many causes of this rhythm, including electrolyte imbalances, ischemia, and genetic disorders, iatrogenic etiologies are important to recognize. Abiraterone is an androgen synthesis antagonist effective in treating prostate cancer, but here we describe a case of severe hypokalemia secondary to abiraterone resulting in polymorphic ventricular tachycardia and cardiac arrest. While this is a potential adverse effect of the medication, severe hypokalemia causing polymorphic ventricular tachycardia and cardiac arrest, as seen in our patient's case, has not been described.

CASE PRESENTATION

A 78-year-old African-American man with history of prostate cancer presents with polymorphic ventricular tachycardia and cardiac arrest. After resuscitation, he was found to be severely hypokalemic and refractory to large doses of repletion. Evaluation of secondary causes of hypokalemia identified the likely culprit to be adverse effects from prostate cancer treatment.

CONCLUSION

A broad differential diagnosis for polymorphic ventricular tachycardia is essential in identifying and treating patients presenting in this rhythm. Here we present a case of iatrogenic polymorphic ventricular tachycardia secondary to oncologic treatment.

Hemophagocytic lymphohistiocytosis in the setting of HELLP Syndrome

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyper activation of the immune system. Rare cases associated with HELLP syndrome and other similar conditions in pregnancy have been reported. Despite the improved survival rates with etoposide and dexamethasone-based regimens, HLH remains a challenging disease. Experience in pregnant patients is exceedingly rare.

PD-1 and PD-L1 as emerging therapeutic targets in gastric cancer: current evidence

Gastric adenocarcinoma is a leading cause of global cancer-related morbidity and mortality, and new therapeutic approaches are needed. Despite the improved outcomes with monoclonal antibodies targeting human epidermal growth factor receptor 2 and vascular endothelial growth factor receptor 2, durable responses are uncommon. Targeting immune checkpoints including PD-1, PD-L1 and CTLA-4 have led to improved survival across several tumor types, frequently characterized by prolonged benefit in responding patients. Tumoral and lymphocyte-derived immunohistochemical staining for PD-1, PD-L1, and tumor mutational burden have shown potential as predictive response biomarkers in several tumor types. Optimal incorporation of immune-mediated therapies into gastric cancer (GC) is an area of intense ongoing investigation and benefit has been demonstrated in smaller studies of advanced patients. Important questions of biomarker selection, roles for molecular characterization, optimal combinatorial approaches, and therapeutic sequencing remain. In this study, current data are reviewed for immune checkpoint inhibitors in GC, and putative biomarkers, ongoing trials, and future considerations are discussed.

Abstract A37: Blockade of ARV7:HIF1α; heterodimers after toptoecan reverses enzalutamide resistance in 22Rv1 cells

Background: Although enzalutamide (ENZ) is initially effective for the treatment of castration-resistant prostate cancer (CRPC), development of ENZ resistance is inevitable. One mechanism for resistance is the emergence of ARV7, an alternative splicing variant of the full length androgen receptor (FL AR) which lacks the androgen binding and hinge region domains. Nuclear translocation of FL AR utilizes the hinge region for coupling to tubulin or importin. ARV7 protein appears to gain nuclear entry independent of the canonical pathway. FL AR has been reported to bind to Hypoxia Inducible Factor-1α (HIF1α). We hypothesized that ARV7 may also heterodimerize with HIF1α in the cytoplasm, facilitating its nuclear localization and transcriptional activity. We previously found that TPT blocks HIF1α translation by targeting topoisomerase I resident on HIF1α mRNA. We therefor determined if ARV7 was bound to HIF1α in ENZ resistant cells and if inhibition of HIF1α translation by topotecan (TPT) could block ARV7 nuclear localization, thereby resensitizing ARV7 expressing cells to ENZ.

Methods: 22Rv1 ENZ resistant prostate cancer cells express comparable levels of full length AR and truncated ARV7 protein. 22Rv1 cells were treated with the hypoxia mimetic cobalt chloride to stabilize HIF1α. Cytoplasmic and nuclear extracts from 22Rv1 cells were used for co-immunoprecipitation (Co-IP) using anit-HIF1α antibody. The effect of TPT on HIF1α and AR/ARV7 expression, and interactions between Topo-1 and HIF1α and AR mRNA were determined by western blot and RNA-IP. The effects of ENZ and TPT on 22Rv1 cell viability were evaluated using the Luminescent cell viability assay.

Results: Co-IP of 22Rv1 whole cell lysates and nuclear extracts with HIF1α-specific antibodies yielded both full length AR and ARV7 protein bands on western blots. Compared with control cells, TPT treatment of 22Rv1 cells under hypoxic conditions resulted in significantly reduced HIF1α accompanied by decreased ARV7 nuclear localization. Topo-I immunoprecipitation confirmed its linkage to HIF-1α mRNA. Surprisingly, we found that Topo-I RNA-IP pulled down AR mRNA as well. Dose-response curves for the TPT / ENZ combination demonstrated synergistic activity, with combination index values of 0.6. Under hypoxic conditions, TPT had an IC50 of 120 nM. pretreatment of 22Rv1 cells with a minimally toxic dose of 15 nM TPT reduced the ENZ IC50 from 93 nM to 60 nM.

Conclusions: Our data indicate that Topo I residing on HIF-1α mRNA provided a druggable target for TPT-mediated inhibition of HIF1α mRNA translation. Clinically achievable TPT concentrations caused HIF1α knockdown in hypoxic 22Rv1 cells in association with diminished nuclear localization of ARV7. 22Rv1 cells showed a synergistic dose-response to the combination of TPT and enzalutamide. These findings support further exploration of TPT modulation of ENZ resistance in the clinic.

Citation Format: John P. Fruehauf, Nathan Farrokh, Sarmen Sarkissian, Jai-Hyun Kim. Blockade of ARV7:HIF1α; heterodimers after toptoecan reverses enzalutamide resistance in 22Rv1 cells. [abstract]. In: Proceedings of the AACR Special Conference on Translational Control of Cancer: A New Frontier in Cancer Biology and Therapy; 2016 Oct 27-30; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2017;77(6 Suppl):Abstract nr A37.

Long-term follow-up of patients with thalamic deep brain stimulation for epilepsy

The authors describe long-term follow-up (mean, 5 years) in patients with anterior (AN) (n = 6) or centromedian (n = 2) thalamic deep brain stimulation (DBS) for epilepsy. Five patients (all AN) had > or = 50% seizure reduction, although benefit was delayed in two until years 5 to 6, after changes in antiepileptic drugs. DBS electrode implantation in AN patients was followed by seizure reduction 1 to 3 months before active stimulation, raising the possibility of a beneficial microthalamotomy effect.

Implementation of a change process to improve outcomes of patients admitted to epilepsy monitoring unit

A continuous quality improvement in health care, combined with measurement of patient and organizational outcomes, is an international trend that promises improvement in meeting the needs of health care consumers in a cost-effective manner. A clinical improvement workshop was conducted in our institution to study the practical methods that can be used by clinical teams to improve the quality and value of health care. This workshop enabled the Epilepsy Team to identify change strategies that potentially could accelerate clinical improvement efforts in the epilepsy monitoring unit (EMU). The Team was able to develop, plan, and test improvements and link these improvements to patient outcomes.

Effects of the acute care nurse practitioner role on epilepsy monitoring outcomes

This study demonstrated the effectiveness of the implementation of the Acute Care Nurse Practitioner (ACNP) role in the management of patients with seizure disorders in an Epilepsy Monitoring Unit. Findings indicated that the ACNP, functioning in an expanded role in the epilepsy program, can make a substantial contribution to organizational outcomes. This is achieved through patient satisfaction and reduction in the number of laboratory tests performed, hospital length of stay, and overall costs.

Clinical indicators contributing to I.C.U. length of stay in elective craniotomy patients with brain tumour

The immediate purposes of this study are (a) to indicate the I.C.U. and hospital length of stay in elective craniotomy patients with brain tumour, and (b) to identify the clinical indicators that contribute to the I.C.U. length of stay. The ultimate purpose is to contribute to a growing body of knowledge in providing quality and cost effective patient outcomes by creating appropriate vehicles for further research in the field of neuroscience. The following clinical indicators are identified: pre-op patient admission to ward or same day admit unit, O.R. cancellations, type of tumour, nursing staff availability, intubation on admission, I.C.U. length of stay, and post-op complications. The results of this pilot study, with sample size of 55 patients, could assist us in the nursing profession to develop an appropriate Care Map for craniotomy patients with brain tumour.

Length of hospital stay and contributing variables in supratentorial craniotomy patients with brain tumour: a pre-care map study

The study included 70 patients admitted to Neurosurgical ICU (NICU) with the diagnosis of Supratentorial Craniotomy for Brain Tumour. These patients were followed throughout their hospitalization in NICU, to the ward and until discharge from hospital. The purposes of the study were (a) to indicated the NICU and floor length of stay (LOS) in this group of patients, prior to the use of care map and compare it to a developed care map, and (b) to identify the variables that contribute toe overall prolonged hospital LOS. The findings indicated that, prior to the use of care map, 68.8% of Supratentorial Craniotomy Patients with Brain Tumour had an ICU LOS of one day. However, only 38.6% of these patients were discharged from hospital within the care map indicated 5 day post ICU, floor LOS. The findings also showed that the overall hospital LOS, in 71.4% of the patients, was over 7 days, as indicated on the developed care cap. Several variables such as patient complications, consults, rehab/placement, patient falls and additional diagnostic tests contributed to the overall pronged hospital LOS. Thus, by monitoring these variables with the use of a care map, may produce measurements to evaluate cost effectiveness, and allow health care professionals to provide more effective and quality patient care.