Pharmacokinetic analysis driven letermovir dosing in pediatric hematopoietic cell transplantation patients with resistant CMV disease.

BACKGROUND: Reactivation of cytomegalovirus (CMV) in CMV-seropositive patients after haploidentical T-cell receptor αß+ /CD19+ depleted hematopoietic cell transplant (HCT) is common. Due to delayed CMV-specific immune reconstitution, patients may require prolonged antiviral therapy, including secondary prophylaxis (SP). We present our clinical experience with the off-label use of letermovir for SP in a severely immunocompromised 2-year-old toddler with refractory pre-B-cell ALL and bilateral retinitis caused by resistant CMV (A594V UL97 mutation) following a haploidentical TCRαß+ /CD19+ depleted HCT. METHODS: The patient underwent measurement of two separate sets of letermovir serum concentrations, drawn at pre-dose, 1 and 4 h (and 8 h during the second therapeutic drug monitoring) post-dose. Pharmacokinetic parameters, including AUC0-24 were calculated, and dose adjustment was performed based on the drug level. RESULTS: While receiving oral letermovir 240 mg once daily without cyclosporine, the observed AUC0-24 was high (75 815 ng h/mL) with a Cmin of 209 ng/mL. The dose was reduced by 25% to 180 mg once daily. Despite the dose reduction, both AUC0-24 and Cmin values further increased to 119 095 ng h/L and 959 ng/mL, respectively. The patient continued oral letermovir 180 mg once daily for about 3 months, with adequate viral suppression (CMV viral load in plasma <150 IU/mL) and no recurrent CMV end-organ disease or adverse events. CONCLUSIONS: Given limited options for anti-CMV therapy in young children with resistant CMV, letermovir could be considered as an alternative antiviral for SP. Further studies are warranted to evaluate the pharmacokinetics of letermovir in pediatric allogeneic HCT recipients.

Peritoneal and Pleural Drains in Pediatric Hematopoietic Cell Transplant Recipients with Veno-Occlusive Disease are Safe and Do Not Adversely Impact Clinical Outcomes.

There is a lack of data on the safety and efficacy of peritoneal drain (PD) and chest tube (CT) in the management of effusions in stem cell transplant recipients with veno-occlusive disease (VOD). In this retrospective pediatric study, clinical outcomes and health resource utilization (HRU) were compared in 32 patients with VOD who had a PD (PD+) post-HCT versus 27 patients who did not (PD-). Nine patients also had a CT (7 PD+ and 2 PD-). PD + patients were more likely than PD-patients to have received myeloablative conditioning (100% vs. 85.2%; p = 0.04) and have severe or very severe VOD (100% vs. 56% p < 0.01). Mechanical obstruction (38%) and hypotension (38%) were common complications, and 13% developed peritonitis. While the frequencies of cardiac dysfunction and acute kidney injury were comparable between both groups, respiratory support and its median duration were higher in PD + patients. The hospital and intensive care unit length of stay, albumin use, and the duration of defibrotide and albumin therapy was significantly longer in PD + patients. At a median follow-up of 1.04 years (range:0.03-14.6), the 2-year overall survival was similar in both groups (53.8% vs. 51.5%; p = 0.73). Although PD use was similar between 1995 and 2007 vs. 2008-2021; (47% vs. 58%; p = 0.65), day+100 mortality was improved in recent years (53.3% vs. 17.8%; p = 0.01), coinciding with the use of defibrotide (0% vs. 84%; p < 0.01). PD in pediatric patients with VOD post-HCT, although associated with increased HRU, was safe when clinically indicated and did not adversely impact clinical outcomes.

70% Ethanol for Decontamination of Central Venous Lines Exposed to Calcineurin Inhibitors.

BACKGROUND: Tacrolimus, commonly used for graft versus host disease prophylaxis is usually administered via a dedicated central venous line (CVL) and trough levels drawn from the unexposed lumen. Being an oil-based medication, it may be adsorbed to the inner lumen of the CVL and result in falsely high levels drawn from an inadvertently exposed lumen. There is no treatment for decontamination of such CVLs, and natural decay occurs over months before the CVL can be used to draw reliable trough levels. OBJECTIVE: The primary objective of the study was to estimate the effectiveness of 70% ethanol locks for decontaminating CVLs exposed to tacrolimus. METHODS: We studied the efficacy of 70% ethanol lock in decontaminating CVLs exposed to tacrolimus in patients during transplant. Trough tacrolimus levels were drawn from the exposed and unexposed (control) lumens at 8:00 am, followed by a 2-mL 70% ethanol lock instilled for a 2-hour dwell into the exposed (intervention) lumen. Trough tacrolimus levels were again drawn from both lumens at 8:00 pm and levels compared for efficacy. RESULTS: All 20 sets showed a high 8 am trough level in the exposed intervention arm (median = 30 ng/mL), significantly greater ( P < 0.0001) than that in the control arm (median = 9.05 ng/mL), and were contaminated. After the 2-hour ethanol lock, 65% of the lumens were decontaminated. The difference between the control and intervention arms was no longer found to be statistically significant ( P = 0.0826). CONCLUSION: A 2-hour 70% ethanol lock is effective for decontamination of CVLs exposed to tacrolimus.

Efficacy and safety of using L-cysteine as a catheter-clearing agent for nonthrombotic occlusions of central venous catheters in children.

Critically ill pediatric patients, especially in the intensive care unit, receive multiple medications and have a higher risk of central venous catheter (CVC) occlusion. If an occlusion occurs immediately after the administration of multiple medications or incompatible medications, either an acidic solution such as 0.1 N hydrochloric acid (HCl) or a basic solution of 1 mEq/mL sodium bicarbonate or 0.1 N sodium hydroxide can be used. However, compounding and storing of 0.1 N HCl has become more complex due to USP <797> guidelines for sterile compounding, and an alternative is needed. We report a series of cases in which L-cysteine was used instead of HCl to clear CVCs occluded due to administration of multiple medications. L-cysteine is a commercially available, sterile solution with a pH of 1­2.5. CVC occlusion was resolved in 10 of the 16 episodes in 13 patients. Two of the 16 occlusions were phenytoin related and would not have responded. An L-cysteine dose of 50 mg was used during 10 of the 16 episodes, 100 mg during 5 episodes, and 25 mg during 1 episode. A correlation between catheter clearance and dose was not observed. Occlusion resolution due to L-cysteine was not correlated to the prior use of tissue plasminogen activator. Metabolic acidosis, adverse effects, or damage to the catheters due to L-cysteine were not observed. On the basis of this limited experience, we propose L-cysteine as an effective alternative to 0.1 N HCl for clearing CVC occlusions caused by drugs with an acidic pKa.