Pharmacokinetics of Ombitasvir, Paritaprevir, Ritonavir, and Dasabuvir in Healthy Chinese Subjects and HCV GT1b-Infected Chinese, South Korean and Taiwanese Patients

Drug-Drug Interactions With Cyclosporine in the Anti-Hepatitis C Viral PrOD Combination Regimen of Paritaprevir/Ritonavir-Ombitasvir and Dasabuvir in Organ Transplant Recipients With Severe Hepatic Fibrosis or Cirrhosis

BACKGROUND

The clinical guidelines suggest that the dosing of cyclosporine (CsA), during combination therapy with paritaprevir/ritonavir-ombitasvir and dasabuvir (PrOD), would be only one-fifth of the pre-PrOD total daily dose to be administered once daily. However, this dosing may not be applicable to all patients depending on their clinical condition. This study focuses on the pharmacokinetic dynamics of PrOD with CsA in Asian organ transplant recipients with severe liver fibrosis or cirrhosis who undergo concurrent treatment with PrOD treatment and CsA. The efficacy and safety of PrOD treatment was also evaluated.

METHODS

Data from 7 patients obtained between January 2017 and September 2017 were retrospectively analyzed. Determinations of the blood concentrations of CsA were made, whether used as a single treatment or in combination therapy with PrOD.

RESULTS

The combination regimen compared with CsA administered alone resulted in a 4.53-fold and 5.52-fold increase in the area under the concentration-time curve from time 0-12 hours (AUC0-12 h) of CsA on days 1 and 15, respectively. In addition, the maximal concentration, time to maximum concentration, and terminal phase elimination half-life (t1/2) of CsA were increased during the combined treatment of PrOD and CsA. The authors proposed reducing the CsA dosage during PrOD treatment to one-seventh of that of the pre-PrOD treatment of the total daily dose to maintain target CsA levels. All patients achieved sustained virologic responses at week 12. There were no episodes of serious adverse events or graft rejections observed.

CONCLUSIONS

Although the combination with PrOD significantly affects the pharmacokinetics of CsA, it is effective and safe with regular monitoring of the CsA blood concentrations and appropriate CsA dose adjustment.

Pharmacological induction of selective endoplasmic reticulum retention as a strategy for cancer therapy

The integrated stress response (ISR) converges on eIF2α phosphorylation to regulate protein synthesis. ISR is activated by several stress conditions, including endoplasmic reticulum (ER) stress, executed by protein kinase R-like endoplasmic reticulum kinase (PERK). We report that ER stress combined with ISR inhibition causes an impaired maturation of several tyrosine kinase receptors (RTKs), consistent with a partial block of their trafficking from the ER to the Golgi. Other proteins mature or are secreted normally, indicating selective retention in the ER (sERr). sERr is relieved upon protein synthesis attenuation and is accompanied by the generation of large mixed disulfide bonded complexes, including ERp44. sERr was pharmacologically recapitulated by combining the HIV-protease inhibitor nelfinavir with ISRIB, an experimental drug that inhibits ISR. Nelfinavir/ISRIB combination is highly effective to inhibit the growth of RTK-addicted cell lines and hepatocellular (HCC) cells in vitro and in vivo. Thus, pharmacological sERr can be utilized as a modality for cancer treatment.

Inhibition of PERK, an endoplasmic reticulum (ER) unfolded protein response (UPR) protein, is a potential pharmacological target for cancer treatment. Here, the authors show that inhibition of PERK under ER stress affects trafficking from the ER to the surface of several key receptor tyrosine kinases, suggesting a selective ER retention.