Individual variation in drug metabolism is a major cause of unpredictable side effects during therapy. Drug metabolism is controlled by a class of orphan nuclear receptors (NRs), which regulate expression of genes such as CYP (cytochrome)3A4 and MDR-1 (multi-drug resistance-1), that are involved in this process. We have found that xenobiotic-mediated induction of CYP3A4 and MDR-1 gene transcription was inhibited by ketoconazole, a commonly used antifungal drug. Ketoconazole mediated its effect by inhibiting the activation of NRs, human pregnenolone X receptor and constitutive androstene receptor, involved in regulation of CYP3A4 and MDR-1. The effect of ketoconazole was specific to the group of NRs that control xenobiotic metabolism. Ketoconazole disrupted the interaction of the xenobiotic receptor PXR with the co-activator steroid receptor co-activator-1. Ketoconazole treatment resulted in delayed metabolism of tribromoethanol anesthetic in mice, which was correlated to the inhibition of PXR activation and downmodulation of cyp3a11 and mdr-1 genes and proteins. These studies demonstrate for the first time that ketoconazole represses the coordinated activation of genes involved in drug metabolism, by blocking activation of a specific subset of NRs. Our results suggest that ketoconazole can be used as a pan-antagonist of NRs involved in xenobiotic metabolism in vivo, which may lead to novel strategies that improve drug effect and tolerance.

Background: Adoptive immunotherapy using CD19-targeted Chimeric Antigen Receptor T-cells (CAR-T) has revolutionized the treatment of relapsed/refractory diffuse large B-cell lymphoma (DLBCL). We have demonstrated the efficacy of FDA-approved axicabtagene ciloleucel (Yescarta) in a multiethnic New York City underserved population with 80% complete response (CR) rate in the first ten patients treated at our institution (Abbasi et al., 2020). There is limited data on the propensity of infections and lymphohematopoietic reconstitution after Day 30 (D30) following CAR-T cell therapy. In this study, we evaluated the prevalence and nature of infectious complications in an expanded cohort of DLBCL patients treated with CD19 CAR-T therapy and its association with the dynamics of leukocyte subpopulation reconstitution post-CAR-T cell therapy. Methods: We conducted a retrospective study of patients who received CAR-T therapy at our institution between 2018-2020. Variables collected include patient demographics, absolute neutrophil (ANC), lymphocyte (ALC) and monocyte counts (AMC) at Day 30, hematologic reconstitution (ANC≥ 1500/µL) at Day 90 (D90), presence or absence of infections after D30 by clinical and/or microbiological parameters. Associations between presence of infection and D30 ANC, ALC, AMC, ANC/ALC ratio, AMC/ALC ratio were assessed using Kruskal-Wallis test. Association between infection and hematologic reconstitution at D90 was done using Chi-square test. Kaplan-Meier curves with log-rank test were used to evaluate overall survival (OS) and progression-free survival (PFS). Results: Nineteen patients were evaluated in our study, consisting of 42% (8) Hispanic, 32% (6) Caucasian, 21% (4) African-American, and 5% (1) Asian subjects. Based on clinical and microbiologic data, 47% (9) developed an infection after D30 (infection group) while 53% (10) of subjects remained infection-free after D30 (non-infection group). The most common infection type observed was viral (11 patients) followed by bacterial (8 patients) and fungal (3 patients) (Table 1). Of 25 total infectious events, 44% (11) were grade 1 or 2 and 48% (12) were grade 3 with 10 being viral in etiology. Two deaths occurred due to an infectious process. Three patients tested SARS-CoV-2 positive and were hospitalized with COVID-19 pneumonia. Median OS and PFS has not been reached in either group. To determine the kinetics of lymphohematopoietic reconstitution and its association with infection risk, we evaluated the relationship between cytopenias and rates of infection after D30. Notably, compared to non-infection group, infection group had a higher median ALC (1000/µL vs 600/µL p=0.04), a lower median ANC/ALC ratio (1.4 vs 4.5 p<0.01) and a lower median AMC/ALC at D30 (0.36 vs 1.33, p=0.01) (Table 2). In addition, patients in the infection group had a lower rate of hematologic reconstitution (ANC >1500/µL) at D90. We observed that only 22% (2) of patients had recovered ANC > 1500/µLin the infection group as opposed to 80% (8) in the non-infection group at D90 (p= 0.038). Rates of cytokine release syndrome (CRS) were comparable between the two groups (55.6% vs 70% p=0.52). Surprisingly, rates of immune-effector cell associated neurotoxicity syndrome (ICANS) was lower (55.6%) in the infection group compared to (90%) non-infection group (p=0.09). Fourteen of 19 patients had follow-up over one year, of which 8 (57%) remained in complete remission (CR). Conclusions: We demonstrate an infection rate of 47% (9) beyond D30 in patients undergoing CD19 CAR-T. Increased ALC, lower ANC/ALC and AMC/ALC ratios at D30 may be predictive of infectious complications. Median OS has not been reached in our cohort. Given the potential clinical impact, our observations should be corroborated using larger datasets. Disclosures Steidl: Pieris Pharmaceuticals: Consultancy; Bayer Healthcare: Research Funding; Stelexis Therapeutics: Consultancy, Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees; Aileron Therapeutics: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Janakiram:ADC Therapeutics, FATE therapeutics, TAKEDA pharmaceuticals: Research Funding. Verma:BMS: Consultancy, Research Funding; acceleron: Consultancy, Honoraria; Janssen: Research Funding; stelexis: Current equity holder in private company; Medpacto: Research Funding.