Association between bridging therapy and posttransplant outcomes in patients with HCC within Milan criteria: A systematic review and meta-analysis.

Liver transplantation is the curative therapy of choice for patients with early-stage HCC. Locoregional therapies are often employed as a bridge to reduce the risk of waitlist dropout; however, their association with posttransplant outcomes is unclear. We conducted a systematic review using Ovid MEDLINE and EMBASE to identify studies published between database inception and August 2, 2023, which reported posttransplant recurrence-free survival and overall survival among patients transplanted for HCC within Milan criteria, stratified by receipt of bridging therapy. Pooled HRs were calculated for each outcome using the DerSimonian and Laird method for a random-effects model. We identified 38 studies, including 19,671 patients who received and 20,148 patients who did not receive bridging therapy. Bridging therapy was not associated with significant differences in recurrence-free survival (pooled HR: 0.91, 95% CI: 0.77-1.08; I2 =39%) or overall survival (pooled HR: 1.09, 95% CI: 0.95-1.24; I2 =47%). Results were relatively consistent across subgroups, including geographic location and study period. Studies were discordant regarding the differential strength of association by pretreatment tumor burden and pathologic response, but potential benefits of locoregional therapy were mitigated in those who received 3 or more treatments. Adverse events were reported in a minority of studies, but when reported occurred in 6%-15% of the patients. Few studies reported loss to follow-up and most had a risk of residual confounding. Bridging therapy is not associated with improvements in posttransplant recurrence-free or overall survival among patients with HCC within Milan criteria. The risk-benefit ratio of bridging therapy likely differs based on the risk of waitlist dropout.

Atypically Modified Carbapenem Antibiotics Display Improved Antimycobacterial Activity in the Absence of ß-Lactamase Inhibitors.

Commercial carbapenem antibiotics are being used to treat multidrug resistant (MDR) and extensively drug resistant (XDR) tuberculosis. Like other ß-lactams, carbapenems are irreversible inhibitors of serine d,d-transpeptidases involved in peptidoglycan biosynthesis. In addition to d,d-transpeptidases, mycobacteria also utilize nonhomologous cysteine l,d-transpeptidases (Ldts) to cross-link the stem peptides of peptidoglycan, and carbapenems form long-lived acyl-enzymes with Ldts. Commercial carbapenems are C2 modifications of a common scaffold. This study describes the synthesis of a series of atypical, C5α modifications of the carbapenem scaffold, microbiological evaluation against Mycobacterium tuberculosis (Mtb) and the nontuberculous mycobacterial species, Mycobacterium abscessus (Mab), as well as acylation of an important mycobacterial target Ldt, LdtMt2. In vitro evaluation of these C5α-modified carbapenems revealed compounds with standalone (i.e., in the absence of a ß-lactamase inhibitor) minimum inhibitory concentrations (MICs) superior to meropenem-clavulanate for Mtb, and meropenem-avibactam for Mab. Time-kill kinetics assays showed better killing (2-4 log decrease) of Mtb and Mab with lower concentrations of compound 10a as compared to meropenem. Although susceptibility of clinical isolates to meropenem varied by nearly 100-fold, 10a maintained excellent activity against all Mtb and Mab strains. High resolution mass spectrometry revealed that 10a acylates LdtMt2 at a rate comparable to meropenem, but subsequently undergoes an unprecedented carbapenem fragmentation, leading to an acyl-enzyme with mass of Δm = +86 Da. Rationale for the divergence of the nonhydrolytic fragmentation of the LdtMt2 acyl-enzymes is proposed. The observed activity illustrates the potential of novel atypical carbapenems as prospective candidates for treatment of Mtb and Mab infections.