Binding characteristics of the doxepin E/Z-isomers to the histamine H1 receptor revealed by receptor-bound ligand analysis and molecular dynamics study.

Doxepin is an antihistamine and tricyclic antidepressant that binds to the histamine H1 receptor (H1R) with high affinity. Doxepin is an 85:15 mixture of the E- and Z-isomers. The Z-isomer is well known to be more effective than the E-isomer, whereas based on the crystal structure of the H1R/doxepin complex, the hydroxyl group of Thr1123.37 is close enough to form a hydrogen bond with the oxygen atom of the E-isomer. The detailed binding characteristics and reasons for the differences remain unclear. In this study, we analyzed doxepin isomers bound to the receptor following extraction from a purified H1R protein complexed with doxepin. The ratio of the E- and Z-isomers bound to wild-type (WT) H1R was 55:45, indicating that the Z-isomer was bound to WT H1R with an approximately 5.2-fold higher affinity than the E-isomer. For the T1123.37V mutant, the E/Z ratio was 89:11, indicating that both isomers have similar affinities. Free energy calculations using molecular dynamics (MD) simulations also reproduced the experimental results of the relative binding free energy differences between the isomers for WT and T1123.37V. Furthermore, MD simulations revealed that the hydroxyl group of T1123.37 did not form hydrogen bonds with the E-isomer, but with the adjacent residues in the binding pocket. Analysis of the receptor-bound doxepin and MD simulations suggested that the hydroxyl group of T1123.37 contributes to the formation of a chemical environment in the binding pocket, which is slightly more favorable for the Z-isomer without hydrogen bonding with doxepin.

Prognostic model for relapsed/refractory transplant-ineligible diffuse large B-cell lymphoma utilizing the lymphocyte-to-monocyte ratio.

We conducted a multi-institutional retrospective study in 100 transplant-ineligible (TI) patients with diffuse large B-cell lymphoma (DLBCL) that relapsed or progressed after first-line R-CHOP (or -like) therapy to develop a robust predictive model for TI relapsed/refractory (r/r) DLBCL, which has a heterogeneous but poor prognosis by currently available treatment modalities other than chimeric antigen receptor T-cell (CAR-T) therapy or bispecific antibodies. The median age at relapse or progression was 76 years. The median progression-free survival (PFS) and overall survival (OS) from the first progression were 11.5 months and 21.9 months, respectively. Multivariate analysis identified low lymphocyte-to-monocyte ratio (LMR), elevated high lactate dehydrogenase, and elevated C-reactive protein at progression as independent predictors of OS. A predictive model based on these three factors, here designated as the Kyoto Prognostic Index for r/r DLBCL (KPI-R), successfully stratified their OS and PFS with statistical significance. In addition, event-free survival less than 24 months for R-CHOP and low LMR were identified as significant predictive factors for non-response in any sequence of salvage therapy. We concluded that LMR is a bonafide predictor of treatment response and prognosis in patients with TI r/r DLBCL, and may be helpful in treatment decision-making.

Clinical impacts of severe thrombocytopenia in the first cycle of azacitidine monotherapy and cytogenetics in patients with myelodysplastic syndrome: The Kyoto Conditional Survival Scoring System.

Azacitidine (AZA) has been one of the standard treatments for transplantation-ineligible patients with myelodysplastic syndrome (MDS); however, hematological toxicities frequently cause treatment interruption in the early phase of the therapy. The present study conducted a multicenter retrospective study to investigate the prognostic impacts of various factors, including factors included in the Revised International Prognostic Scoring System (IPSS-R) and severe cytopenia in the early phase of AZA monotherapy in 212 patients with MDS. Severe cytopenia was evaluated after the initiation of therapy by absolute neutrophil counts on the 29th day after AZA (ANC29) initiation, and red cell concentrates (RCC) and platelet concentrate (PC) transfusion units required within 28 days from the start of AZA, designated in the present study as RCC28 and PC28, respectively. The survival period was determined from the 29th day of AZA treatment to death from any cause as the conditional survival period after the first cycle of AZA (CS-AZA1). Multivariate analysis demonstrated that severe thrombocytopenia defined by >30 units of PC28 and very poor risk cytogenetics according to IPSS-R were independent prognostic factors for CS-AZA1. The Kyoto Conditional Survival Scoring System was subsequently developed by incorporating severe thrombocytopenia defined by PC28 and very poor risk cytogenetics, which successfully stratified the risks of the patients in CS-AZA1. In conclusion, extreme PC transfusion dependency during the first cycle of AZA and very poor risk cytogenetics are important prognostic factors in AZA monotherapy for MDS.