A Case Report of Drug Interactions Between Nirmatrelvir/Ritonavir and Tacrolimus in a Patient With Systemic Lupus Erythematosus.

Nirmatrelvir/ritonavir is a treatment for COVID-19 consisting of nirmatrelvir, which has anti-SARS-CoV-2 activity, and ritonavir, a booster to maintain blood levels. Ritonavir is known to be a potent inhibitor of cytochrome P450 3A (CYP3A), and interactions with CYP3A-metabolized drugs, such as the immunosuppressant tacrolimus, can be problematic. Ritonavir's inhibition of CYP3A is irreversible due to covalent binding, and its inhibitory effects are expected to persist until replaced by new CYP3A. Here, we report a case where the combination of nirmatrelvir/ritonavir and tacrolimus resulted in toxic tacrolimus blood levels. A patient on tacrolimus for systemic lupus erythematosus (SLE) developed COVID-19 and was prescribed nirmatrelvir/ritonavir. After starting the combination of nirmatrelvir/ritonavir and tacrolimus, the patient's tacrolimus blood levels became abnormally high, leading to the discontinuation of these drugs due to symptoms of tacrolimus toxicity. Even after ritonavir blood levels had fallen below the detection limit, the decline in tacrolimus blood levels was delayed. The CYP3A inhibition of ritonavir persists even when its blood concentration decreases, emphasizing the need for careful consideration of concomitant medications before starting nirmatrelvir/ritonavir therapy. Adjustments or discontinuation may be necessary.

BRCA2 represses the transcriptional activity of pS2 by E2-ERα.

Germline mutations to the breast cancer 2 (BRCA2) gene have been associated with hereditary breast cancer. In addition to estrogen uptake, BRCA2 expression increases in the S phase of the cell cycle and largely contributes to DNA damage repair associated with DNA replication. However, the role of BRCA2 in estrogen induction remains unclear. An expression plasmid was created to induce BRCA2 activation upon the addition of estradiol by introducing mutations to the binding sequences for the transcription factors USF1, E2F1, and NF-κB within the promoter region of BRCA2. Then, the estrogen receptor (ER) sites of the proteins that interact with BRCA2 upon the addition of estradiol were identified. Both proteins were bound by the helical domain of BRCA2 and activation function-2 of the ER, suggesting that this binding may regulate the transcriptional activity of pS2, a target gene of the estradiol-ER, by suppressing the binding of SRC-1, a coactivator required for activation of the transcription factor.

Use of Mycophenolate Mofetil Suspension as Part of Induction Therapy After Living-Donor Liver Transplant.

OBJECTIVES: The aim of this study was to evaluate recipient safety, tolerability, and pharmacokinetics of mycophenolate mofetil suspension compared with mycophenolate mofetil capsules as part of induction therapy after living-donor liver transplant. MATERIALS AND METHODS: Between July 2017 and April 2019, we retrospectively enrolled 20 adult primary living-donor liver transplant recipients. Recipients were divided into 3 groups: group 1 received mycophenolate mofetil suspension of 3000 mg (n = 6), group 2 received 3000 mg mycophenolate mofetil via opened capsules (n = 8), and group 3 received mycophenolate mofetil suspension of 2000 mg (n = 6). Administration was started on postoperative day 1, with tacrolimus administered on postoperative day 2 or day 3. RESULTS: The values of area under the plasma concentration time curve for 0 to 12 hours were significantly higher in the 3000 mg/day mycophenolate mofetil suspension group than in the 2000 mg/day mycophenolate mofetil suspension group (P = .024) and in the 3000mg/day mycophenolate mofetil capsule group (P = .013). Significant positive correlations were shown between blood concentration at 8 hours after administration and the plasma concentration time curve for 0 to 12 hours (r2 = 0.96; P < .001) in patients in the suspension group. No patients required mycophenolate mofetil reduction because of leukopenia and diarrhea. Only 1 biopsy-proven acute cellular rejection was recognized in the mycophenolate mofetil suspension group (at 2000 mg/day). There were no significant differences in frequency of opportunistic infections among the 3 groups. CONCLUSIONS: Mycophenolate mofetil suspension is useful as part of immunosuppressive induction therapy after living-donor liver transplant because its concentration increases greater than that of mycophenolate mofetil capsules and because of the low risk of rejection and adverse events.

Influence of POR*28 Polymorphisms on CYP3A5*3-Associated Variations in Tacrolimus Blood Levels at an Early Stage after Liver Transplantation.

It is well known that the CYP3A5*3 polymorphism is an important marker that correlates with the tacrolimus dose requirement after organ transplantation. Recently, it has been revealed that the POR*28 polymorphism affects the pharmacokinetics of tacrolimus in renal transplant patients. In this study, we examined whether POR*28 as well as CYP3A5*3 polymorphism in Japanese recipients and donors would be another biomarker for the variation of tacrolimus blood levels in the recipients during the first month after living-donor liver transplantation. We enrolled 65 patients treated with tacrolimus, who underwent liver transplantation between July 2016 and January 2019. Genomic DNA was extracted from whole-blood samples, and genotyping was performed to examine the presence of CYP3A5*3 and POR*28 polymorphisms in the recipients and donors. The CYP3A5*3/*3 genotype (defective CYP3A5) of the recipient (standard partial regression coefficient [median C/D ratio of CYP3A5 expressor vs. CYP3A5 non-expressor, p value]: Pod 1-7, ß= -0.389 [1.76 vs. 2.73, p < 0.001]; Pod 8-14, ß = -0.345 [2.03 vs. 2.83, p < 0.001]; Pod 15-21, ß= -0.417 [1.75 vs. 2.94, p < 0.001]; Pod 22-28, ß = -0.627 [1.55 vs. 2.90, p < 0.001]) rather than donor (Pod 1-7, ß = n/a [1.88 vs. 2.76]; Pod 8-14, ß = n/a [1.99 vs. 2.93]; Pod 15-21, ß = -0.175 [1.91 vs. 2.94, p = 0.004]; Pod 22-28, ß = n/a [1.61 vs. 2.67]) significantly contributed to the increase in the concentration/dose (C/D) ratio of tacrolimus for at least one month after surgery. We found that the tacrolimus C/D ratio significantly decreased from the third week after transplantation when the recipient carried both CYP3A5*1 (functional CYP3A5) and POR*28 (n = 19 [29.2%], median C/D ratio [inter quartile range] = 1.58 [1.39-2.17]), compared with that in the recipients carrying CYP3A5*1 and POR*1/*1 (n = 8 [12.3%], median C/D ratio [inter quartile range] = 2.23 [2.05-3.06]) (p < 0.001). In conclusion, to our knowledge, this is the first report suggesting that the POR*28 polymorphism is another biomarker for the tacrolimus oral dosage after liver transplantation in patients carrying CYP3A5*1 rather than CYP3A5*3/*3.

Neutrophil Gelatinase-Associated Lipocalin Is Not Associated with Tacrolimus-Induced Acute Kidney Injury in Liver Transplant Patients Who Received Mycophenolate Mofetil with Delayed Introduction of Tacrolimus.

Tacrolimus is widely used as an immunosuppressant in liver transplantation, and tacrolimus-induced acute kidney injury (AKI) is a serious complication. The urinary neutrophil gelatinase-associated lipocalin (NGAL) level has been linked to tacrolimus-induced AKI in patients starting tacrolimus treatment the morning after liver transplantation. Here we tested this association using a different immunosuppression protocol: Mycophenolate mofetil administration beginning on Postoperative Day 1 and tacrolimus administration beginning on Postoperative Day 2 or 3. Urine samples were collected from 26 living donor liver transplant recipients before (Postoperative Day 1) and after (Postoperative Day 7 or 14) tacrolimus administration. NGAL levels were measured via enzyme-linked immunosorbent assays, as were those of three additional urinary biomarkers for kidney diseases: Monocyte chemotactic protein-1 (MCP-1), liver-type fatty acid-binding protein (L-FABP), and human epididymis secretory protein 4 (HE4). HE4 levels after tacrolimus administration were significantly higher in patients who developed AKI (n = 6) than in those who did not (n = 20), whereas NGAL, MCP-1, and L-FABP levels did not differ significantly before or after tacrolimus administration. These findings indicate that NGAL may not be a universal biomarker of AKI in tacrolimus-treated liver transplant recipients. To reduce the likelihood of tacrolimus-induced AKI, our immunosuppression protocol is recommended.

[A Case of Ipsilateral Breast Tumor Recurrence with Breast Ulcer].

The patient was a 61-year-old woman with a history of treatment for breast cancer. She had undergone left breast-conserving surgery and axillary lymph node dissection followed by radiation therapy for left breast cancer when she was 43 years old and later presented to our hospital with a chief complaint of a left breast ulcer with a messy exudate. Core needle biopsy (CNB)from the ulcer showed no malignancy. PET-CT showed low FDG uptake at the left breast and high FDG uptake at a contralateral axillary lymph node. CNB of a contralateral axillary lymph node showed metastasis of breast cancer. She underwent left mastectomy and right axillary lymph node dissection for local control. Ipsilateral breast tumor recurrence in the left breast and contralateral axillary metastases were identified in the final pathological findings. The patient was treated with FEC 100 and tri-weekly docetaxel and has been recurrence-free for 2 years after surgery.

A high-sodium diet in streptozotocin-induced diabetic rats impairs endothelium-derived hyperpolarizing factor-mediated vasodilation.

We examined endothelium-derived hyperpolarizing factor (EDHF)-mediated relaxation of mesenteric arteries in high-sodium loaded streptozotocin (STZ)-induced diabetic rats. The study shows that acetylcholine (ACh)-induced, EDHF-mediated relaxation is relatively maintained in STZ-induced diabetic rats, but after a high-sodium diet was given, the function was significantly impaired in STZ-induced diabetic rats.