IVIG for Infection Prevention After CAR-T-Cell Therapy

Incidence rate of serious bacterial infections in the modified intention-to-treat (mITT) population

Grade 2 or 3 bacterial infections. Only microbiologically confirmed infections will be included. Microbiological documentation of an infection consists of isolation of the pathogen by culture from a sterile (definite) or nonsterile (probable) site (if from a nonsterile site, the organism had to be clinically judged to be pathogenic). Will describe the number and type of infections in each study arm and calculate incidence rate estimates and 95% confidence intervals (CIs) for infections. Will compare serious bacterial infection incidence rates between study arms using negative binomial regression with an offset to account for days-at-risk. Will construct multivariable Cox proportional hazards models of time-to-first serious bacterial infection.

Incidence rate of serious bacterial infections in ITT and per-protocol populations and of any serious infection or any infection after CD19 CARTx

Will use similar analytic approaches as in the primary outcome analysis to evaluate secondary outcomes (any serious infection, any infection) and all outcomes in pre-specified populations (mITT, per-protocol, ITT). Will explore outcomes restricted to early (days 0-28) and later (days 29-168) post-CARTx time periods. Plot cumulative incidence curves of time-to-first serious bacterial infection by study arm. Incidence rate ratios, hazard ratios (HR), and their 95% CIs will be reported. Will use one-sided testing to determine whether the rate of infections is significantly lower in the immunoglobulin replacement therapy (IGRT) versus placebo arms.

Levels of total IgG, IgG subclasses, and total Streptococcus (S.) pneumoniae IgG

Will graphically display mean total IgG levels, IgG subclasses, and S. pneumoniae IgG titers over time, stratified by study arm. Will use generalized estimating equations (GEE) models to compare means by randomization arm. Will test the association of each IgG metric as time-varying covariates with risk of subsequent infection (serious bacterial, any serious, any) at any time post-randomization and separately during early (days 0-28) and later (days 29-168) periods post-CARTx using Cox proportional hazard models. Model estimates will be presented as HRs with 95% CIs.

Health resource utilization (HRU)

Will describe HRU metrics by study arm (overall and by relationship to study drug infusion or infection). Will compute rates (per 1000 person-days) for each metric (e.g., days alive and out of the hospital, days of antibiotics, outpatient visits, emergency room visits, hospitalizations, adverse events) and compare between study arms using rate ratios with p-values and 95% CIs calculated by Poisson or negative binomial regression.

Incidence and severity of cytokine release syndrome (CRS) and/or immune effector cell-associated neurotoxicity syndrome (ICANS)

Will plot cumulative incidence curves, stratified by study arm, of any and grade \>= 3 CRS, ICANS, or both, and compare hazard ratios using multivariable Cox proportional hazards models to adjust for stratification variables and potential confounders. To account for multiple comparisons, we will consider the Benjamini-Hochberg procedure for controlling the false discovery rate.