Valspodar

In this study, we compared outcomes of intensified myeloablative conditioning regimens using large registry data from Japan (Japanese Society for Transplantation and Cellular Therapy) and the United States (Center for International Blood and Marrow Transplant Research).

Adult patients who underwent their first myeloablative allogeneic hematopoietic stem cell transplantation (HSCT) for acute leukemia in remission between 2010 and 2018 using conditioning regimens of cyclophosphamide plus total‐body irradiation (CY/TBI), CY/TBI+cytarabine (AraC), or CY/TBI+etoposide (VP16) were included.

The acute myeloid leukemia (AML) cohort (N = 480, 38.8%) indicated that overall survival (OS) was poorer in CY/TBI+AraC (hazard ratio [HR] 1.46, p < 0.001) and CY/TBI+VP16 (HR 1.39, p = 0.059) compared to CY/TBI. Relapse was not suppressed, while treatment‐related mortality (TRM) was significantly higher (HR 1.78 and 1.74, p < 0.001 and 0.018, respectively). In the acute lymphoblastic leukemia (ALL) cohort (N = 3901, 61.2%), OS was comparable among these regimens. With intensified regimens, relapse was significantly suppressed in CY/TBI+VP16 (HR 0.74, p = 0.005), while TRM was higher (HR 1.21, p = 0.077). No interactions were observed regarding the country.

In AML adding AraC and VP16 to CY/TBI had an adverse effect on OS. Conversely, in ALL, adding VP16 or AraC to CY/TBI did not affect survival, but the addition of VP16 reduced the risk of relapse.

The authors have confirmed clinical trial registration is not needed for this submission.

The membrane efflux transporter P-glycoprotein (P-gp, [ABCB1, MDR1]) exports a wide range of xenobiotic compounds, resulting in a continuous first line of defense against toxicant accumulation at basal expression levels, and contributing to the multixenobiotic resistance (MXR) phenotype at elevated expression levels. Relatively little information exists on P-gp inhibition in fish by chemosensitizers, compounds which lower toxicity thresholds for harmful P-gp substrates in complex mixtures. The effects of four known mammalian chemosensitizers (cyclosporin A [CsA], quinidine, valspodar [PSC833], and verapamil) on the P-gp-mediated transport of rhodamine 123 (R123) and cortisol in primary cultures of rainbow trout (Oncorhynchus mykiss) hepatocytes were examined. Competitive accumulation assays using 25 µM R123 or cortisol and varying concentrations of chemosensitizers (0-500 µM) were used. CsA, quinidine, and verapamil inhibited R123 export (IC50 values ± SE: 132 ± 60, 83.3 ± 27.2, and 43.2 ± 13.6 µM, respectively). CsA and valspodar inhibited cortisol export (IC50 values: 294 ± 106 and 92.2 ± 34.9 µM, respectively). In an ATP depletion assay, hepatocytes incubated with all four chemosensitizers resulted in lower free ATP concentrations, suggesting that they act via competitive inhibition. Chemosensitizers that inhibit MXR transporters are an important class of environmental pollutant, and these results show that rainbow trout transporters are inhibited by similar chemosensitizers (and mostly at similar concentrations) as seen in mammals and other fish species.