Difference in immunosuppressant dose requirement when transitioning to isavuconazole from other azoles in thoracic transplant recipients.

The triazole antifungal isavuconazole (ISAVU) is used for prevention and treatment of fungal infections in solid organ transplant (SOT). SOT recipients commonly need to transition from one azole to another due to breakthrough infection, toxicity, or other reasons. The purpose of our study was to evaluate the effect of ISAVU on immunosuppressant concentrations in thoracic transplant recipients when ISAVU was started de novo or transitioned from another azole. We conducted a single-center retrospective cohort study including 68 patients (51 lung, 14 heart, and 3 heart/lung transplant). Concentration to dosage ratios (C/D) of immunosuppressants were assessed at baseline, day 3, and weekly for 9 weeks. When starting ISAVU de novo, we observed a temporary doubling of tacrolimus exposure. Cyclosporine and sirolimus required dose decreases. Tacrolimus C/D increased by 110% at day 3 in patients started on ISAVU de novo then returned to baseline C/D ± 17% weeks 2-9 (n = 8). One cyclosporine patient started on ISAVU de novo had variable C/D, and C/D increased by 219% ± 72% in 2 sirolimus patients. When transitioning from other azoles, tacrolimus and cyclosporine required about twice the initial dose. After week 1, tacrolimus C/D decreased by 53% ± 6% in patients transitioned from posaconazole (n = 33), voriconazole (n = 14), or fluconazole (n = 2). Cyclosporine C/D decreased by 45% ± 16% in patients transitioning from other azoles (posaconazole [n = 2], voriconazole [n = 2], fluconazole [n = 1]). Sirolimus C/D decreased by 73% ± 13% in patients transitioned from posaconazole (n = 7). Aside from the initial loading phase, ISAVU had a lesser degree of interaction with immunosuppressants than other azoles in loading phase, ISAVU had a lesser degree of interaction with immunosuppressants than other azoles in adjustments for the 4-week period after initiating antifungal therapy with ISAVU or switching from another agent.

Low dose posaconazole delayed release tablets for fungal prophylaxis in lung transplant recipients.

In November 2013, posaconazole delayed release (DR) tablets were approved by the FDA with the labeled dose of 300 mg daily for fungal prophylaxis. There are no studies demonstrating the appropriate dose in lung transplant recipients (LTR). We performed a 2-center retrospective cohort study of LTR taking posaconazole DR tablets for prophylaxis between January 2014 and January 2017. Mean serum trough concentrations and percentage of measurements ≥0.7 mcg/mL were compared by daily dose. Forty-nine subjects with 156 steady state serum posaconazole concentrations were included. There was a significant difference in percentage of first measured concentration ≥0.7 mcg/mL by initial daily dose (P = .04). The mean serum posaconazole concentration by dose was 0.9 (±0.42) mcg/mL for 100 mg daily, 1.66 (±0.91) mcg/mL for 200 mg daily, 2.39 (±1.49) mcg/mL for 300 mg daily, and 1.75 (±0.21) mcg/mL for 400 mg daily (P < .001). Mean concentrations were at goal in 63.3%, 96.9%, 94.9%, and 100% of subjects taking 100 mg, 200 mg, 300 mg, and 400 mg daily respectively (P = .04). Our results suggest that doses less than 300 mg daily of posaconazole DR tablets may be adequate to achieve target serum concentrations in LTR. Larger studies are needed to confirm these findings.

Sirolimus Long-Term Tolerability and Impact on Kidney Function in Lung Transplantation: A Single-Center Experience.

BACKGROUND: After lung transplant, 2 common complications are calcineurin inhibitor (CNI) induced nephrotoxicity and bronchiolitis obliterans syndrome. The objective of this study was to investigate the long-term effects of sirolimus conversion after lung transplantation. METHODS: This was a retrospective cohort study of patients who had undergone lung transplantation at a single center from June 2003 to December 2016. We compared patients converted to a sirolimus-based regimen to those maintained on our standard tacrolimus-based regimen. Kidney function, pulmonary function, and immunosuppression concentrations were compared between the groups. Additionally, indications, toxicity monitoring parameters, and discontinuation rates for sirolimus were collected. RESULTS: During the study period, 176 of the 205 patients who underwent lung transplants were converted to a sirolimus-containing regimen (86%). The most common reason for sirolimus initiation was impairment of kidney function or CNI-associated neurotoxicity. Sirolimus was initiated at a median of 150 days post-transplantation and continued for a medium time of 5.02 (2.27-7.85) years. Of those patients converted to sirolimus, 39 (22%) had sirolimus subsequently discontinued secondary to an adverse event. No difference in pulmonary function was found between the groups at 1- and 3-years post-transplantation. In the sirolimus group, the median estimated glomerular filtration rate improved by 8.6 mL/min/1.73 m2 at 3 months post-conversion (P < .001), which was maintained at both 1 and 3 years (P = .014 and .025, respectively). CONCLUSION: Sirolimus is a viable immunosuppressant option after lung transplant, which successfully allows for the reduction or withdrawal of the CNI, resulting in sustained improvement in kidney function.

Improved Time in Therapeutic Range with International Normalized Ratio Remote Monitoring for Patients with Left Ventricular Assist Devices.

Despite advances in therapy, bleeding and thromboembolic events are frequent complications in patients with left ventricular assist device (LVAD) support. Maintaining warfarin in therapeutic range has been shown to be more challenging in this patient population compared to other indications. Patients with LVADs on warfarin typically are within goal international normalized ratio (INR) range 36-57% of the time, compared to about 65% for other indications. The goal of this study was to evaluate if an INR remote monitoring system along with the implementation of a standardized warfarin management protocol improves warfarin time in therapeutic range (TTR) for patients with LVADs. This single-center, retrospective, observational study included 78 patients with LVADs that were followed at our academic center from January 2015 to October 2017. In October 2016, we updated our warfarin management protocol and implemented a remote monitoring system with patients' weekly INR results monitored. The primary objective of the study was to determine the difference between TTRs in remote monitoring versus standard monitoring. We found that the average TTR was significantly higher in the remote monitoring group compared to the standard monitoring cohort (61.1% vs. 40.0%, p < 0.005). However, bleeding, thrombotic incidence, and hospital readmission rates were similar between the two patient cohorts. Remote monitoring improved warfarin TTR significantly in this study and may have the potential to improve anticoagulation-related outcomes in patients with LVADs.

Drug Interaction between Sirolimus and Ranolazine in a Kidney Transplant Patient.

Purpose. The case of a kidney transplant recipient who experienced a probable drug interaction between sirolimus and ranolazine is reported. Summary. The narrow therapeutic window of immunosuppressive therapy in transplant recipients requires close monitoring for potential drug-drug interactions. The patient, a 57-year-old Caucasian male kidney transplant recipient, was stable for years on sirolimus as his primary immunosuppressive agent and had a history of chronic angina, for which he was prescribed ranolazine. Upon addition and dose escalation of ranolazine, whole blood sirolimus levels more than tripled, rising to immeasurably high concentrations. After holding sirolimus on multiple occasions and reducing dosage more than 50%, blood levels returned to therapeutic range, while continuing ranolazine. Conclusion. Since ranolazine is a documented P-GP and CYP3A inhibitor, and sirolimus a known substrate for both pathways, it is proposed that ranolazine inhibition of P-GP and CYP3A4 contributed to the significant elevation in sirolimus exposure. No alternative causes for the rise in sirolimus exposure were found, and assessment with the Drug Interaction Probability Scale finds this interaction to be probable. Clinicians should be aware of the potential for this interaction to cause elevated sirolimus exposure and subsequent increase in clinical effect or toxicity, in this case overimmunosuppression.

Increased incidence of cutaneous squamous cell carcinoma in lung transplant recipients taking long-term voriconazole.

BACKGROUND: Voriconazole has been used for prevention and treatment of fungal infections in patients after lung transplantation. We postulate that long-term use of voriconazole may increase the risk of squamous cell carcinoma of the skin in these patients. METHODS: The study included 120 patients who received lung transplantation at UC San Diego Health System between July 2000 and June 2006. All patients received a similar initial immunosuppression regimen, and 43 (35.8%) received voriconazole for treatment or prophylaxis for fungal diseases. In this retrospective study, we compared the incidence of squamous cell carcinoma in lung transplant recipients with or without voriconazole use. RESULTS: Squamous cell carcinomas developed in 39.5% of patients (17 of 43) who received voriconazole for prophylaxis or treatment of fungal disease, compared with 19.5% (15 of 77) who did not receive voriconazole (p = 0.03). Four patients died of metastatic squamous cell carcinoma, all in the voriconazole group. Multiple logistic regression analysis showed older age at the time of transplant (odds ratio [OR], OR (95% CI) 2.8 (1.5-5.5)), skin cancer pre-transplant (OR, 11.0 (1.76-68.4), and longer voriconazole therapy (OR, 1.8 (1.3-2.6)) were independent risk factors for development of skin cancer after transplant. CONCLUSIONS: Our results suggest that long-term use of voriconazole may be associated with development of cutaneous squamous cell carcinoma in patients after lung transplant. Greater clinical aggressiveness of skin cancer was also noted in these patients.