Hypogammaglobulinemia and Infection Risk in Chronic Lymphocytic Leukemia (CLL) Patients Treated with CD19-Directed Chimeric Antigen Receptor T (CAR-T) Cells
Authors: Uy Natalie F. , Pequignot Edward , Frey Noelle V. , Davis Megan , Hexner Elizabeth O. , Schuster Stephen J. , Gill Saar , Loren Alison W. , Grupp Stephan A , Melenhorst J. Joseph , Lacey Simon F , Fraietta Joseph A , Gilmore Joan , Lledo Lester , Hwang Wei-Ting , Siegel Don L. , Levine Bruce L , June Carl H , Porter David L. 
Published: November 2020

INTRODUCTION
Anti-CD19 CAR T-cell immunotherapy is promising for patients with relapsed/refractory CLL. Hypogammaglobinemia can result from normal CD19+ B-cell depletion by CAR-T cells. CLL patients are already at risk for infections due to impaired immune function, lymphodepletion prior to CAR-T cells infusion, and immunosuppressive therapies. Intravenous immunoglobulin (IVIG) is used to manage hypogammaglobulinemia, although standard criteria for IVIG administration in this setting has not been established. We studied the incidence of hypogammaglobinemia and report infectious complications, risk factors, IVIG use, and clinical outcomes for CLL patients treated with anti-CD19 CAR-T cells.
METHODS
Adult CLL patients who received CD19-directed CAR-T therapy in 3 clinical trials (NCT01029366, NCT01747486, NCT02640209) from July 2010 to February 2020 were included. We reviewed demographics, available IgG levels, IVIG use, and clinical outcomes with a particular focus on infectious complications. Hypogammaglobulinemia was defined as IgG &lt;4.5 g/L. Infections during the first 28 days after CAR-T were excluded to account for chemotherapy-induced neutropenia. CLL response was based on the 2008 International Workshop Group on CLL as per study protocols. The use of IVIG for hypogammaglobulinemia was at the discretion of investigator or treating physician. Fisher's test, Wilcoxon test and logrank were used for data analysis.
RESULTS
Records of 71 adult patients with CLL were reviewed; 4 were excluded from further analysis as they did not have IgG levels after CAR-T. The median age at time of CAR-T was 63 years (range 43-78 years). 31 patients (46%) were alive, 31 (46%) were deceased, and 5 (7%) were lost to follow up at time of review. Median follow up for all patients was 33 months (range 2-114 months).
Of the 55 patients with an IgG level prior to CAR-T infusion, 24 (44%) had hypogammaglobulinemia at baseline After CAR-T infusion, 54 of 67 patients (81%) developed new or persistent hypogammaglobulinemia, and 40 of these patients (74%) received IVIG (Table 1). Forty-eight patients (72%) received at least one infusion of IVIG after CAR-T. Median time to initiation of IVIG after CAR-T infusion was 2.8 months (range 0.1-71.2 months). IVIG was used in 29 of 35 (83%) responders (defined as PR or CR) vs 19 of 32 (59%) in non-responders (defined as NR or PD) (p=0.056). There was no difference in survival observed based on whether or not patients had hypogammaglobulinemia (Figure).
42 patients (63%) had documented infections not related to chemotherapy-induced neutropenia. Fifteen (22%) had one documented infection, and 27 (40%) had more than one documented infection. There were 13 infections documented in patients who did not have hypogammaglobulinemia; the most common were ENT/sinus infections (5), bacteremia (2), URI (2), and other (2). There were 94 infections documented in patients who developed or had persistent hypogammaglobulinemia; the most common were lower respiratory tract infection/pneumonia (21), URI (20), and ENT/sinus infections (13). Complete and partial responders had more infections compared to non-responders or those who progressed (p = 0.01). Patients with hypogammaglobulinemia after CAR-T had an average of 1.74 (range 0-15) infections vs 1 (range 0-3) in patients without hypogammaglobulinemia. Patients who received IVIG had more infections (p=0.003); without IVIG the average number of infections was 0.58 (range 0-3), and with IVIG, the average number of infections was 2.00 (range 0-15).
CONCLUSION
Evaluating clinical outcomes with infections after CAR-T and potential strategies to minimize infection risk may improve morbidity and mortality in CLL patients. Use of IVIG was driven by individual practice, with heterogeneity regarding indication, frequency, and duration of treatment, though there was no difference in patient characteristics or response in patients who did or did not develop hypogammaglobulinemia. Patients who responded to CAR-T had more frequent infections, as might be expected in the setting of transient or persistent B- cell aplasia or hypoplasia. Patients who had more infections were more likely to receive IVIG. Further studies to define criteria for IVIG repletion in CLL patients treated with CD19-directed CAR-T cells may be incorporated in a standard clinical management algorithm.
Table 1

Disclosures
Frey: Amgen: Consultancy, Honoraria; Syntax: Consultancy, Honoraria; Kite Pharma: Consultancy, Honoraria. Davis:Tmunity Therapeutics, Inc.: Consultancy, Patents & Royalties, Research Funding; Cellares Corporation: Membership on an entity's Board of Directors or advisory committees; Novartis Institutes for Biomedical Research: Patents & Royalties. Hexner:Blueprint Medicines Corporation: Other: serves on a data safety monitoring committee, Research Funding; Novartis: Research Funding; Samus Therapeutics: Research Funding; American Board of Internal Medicine: Other: member of the hematology exam committee. Schuster:Novartis, Genentech, Inc./ F. Hoffmann-La Roche: Research Funding; AlloGene, AstraZeneca, BeiGene, Genentech, Inc./ F. Hoffmann-La Roche, Juno/Celgene, Loxo Oncology, Nordic Nanovector, Novartis, Tessa Therapeutics: Consultancy, Honoraria. Gill:Fate: Consultancy; Sensei: Consultancy; Aileron: Consultancy; Tmunity Therapeutics: Research Funding; Carisma Therapeutics: Patents & Royalties, Research Funding; Novartis: Research Funding. Grupp:Servier: Research Funding; Kite/Gilead: Research Funding; Roche: Consultancy; GlaxoSmithKline: Consultancy; Humanigen: Consultancy; CBMG: Consultancy; Jazz: Other: SSC; Adaptimmune: Other: SAB; TCR2: Other: SAB; Cellectis: Other; Juno/BMS: Other; Janssen/JnJ: Consultancy; CRISPR Therapeutics/Vertex Pharmaceuticals: Other; Allogene: Other; Novartis: Consultancy, Other: SSC, Research Funding. Melenhorst:Johnson & Johnson: Consultancy, Other: Speaker; Novartis: Other: Speaker, Research Funding; Kite Pharma: Research Funding; IASO Biotherapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Poseida Therapeutics: Consultancy; Simcere of America: Consultancy. Lacey:Novartis: Patents & Royalties: CAR T cells, Research Funding; Tmunity: Research Funding; Cabaletta: Research Funding; Carisma: Research Funding. Fraietta:Tmunity: Research Funding. Hwang:Novartis: Research Funding; Tmunity Therapeutics: Research Funding. Siegel:Novartis: Patents & Royalties; Tmunity: Patents & Royalties; Poseida: Membership on an entity's Board of Directors or advisory committees; Vetigenics: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees. Levine:Terumo: Consultancy; Novartis: Consultancy, Patents & Royalties: Dr. Levine has a patent Methods for treatment of cancer (US 8906682) (US 8916381)(US 9101584) with royalties paid to University of Pennsylvania, a patent Compositions for treatment of cancer (US 8911993) (US 9102761) (US 9102760) with royalties paid to U; Lilly Asia Ventures: Consultancy; Avectas: Membership on an entity's Board of Directors or advisory committees; Patheon: Membership on an entity's Board of Directors or advisory committees; Immuneel: Membership on an entity's Board of Directors or advisory committees; Incysus: Membership on an entity's Board of Directors or advisory committees; Ori Biotech: Membership on an entity's Board of Directors or advisory committees; Vycellix: Membership on an entity's Board of Directors or advisory committees; Tmunity Therapeutics: Current equity holder in private company, Research Funding. June:Bluesphere Bio: Membership on an entity's Board of Directors or advisory committees; Cabaletta Bio: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees; Carisma Therapeutics: Membership on an entity's Board of Directors or advisory committees; Cellares: Membership on an entity's Board of Directors or advisory committees; Celldex: Consultancy, Membership on an entity's Board of Directors or advisory committees; DeCART Therapeutics: Membership on an entity's Board of Directors or advisory committees; Immune Design: Membership on an entity's Board of Directors or advisory committees; Kiadis Pharma: Current equity holder in private company; Novartis: Patents & Royalties, Research Funding; Tmunity Therapeutics: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; Ziopharm Oncology: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees. Porter:Tmunity: Patents & Royalties; Novartis: Honoraria, Other: Advisory board, Patents & Royalties: CAR T cells for CD19+ malignancies, Research Funding; American Board of Internal Medicine: Other: Member, exam writing committee (end date Oct 2019); National Marrow Donor Program: Membership on an entity's Board of Directors or advisory committees; Janssen: Other: Advisory board; Genentech/Roche: Current equity holder in publicly-traded company, Other: Spouse employment (ended Sept 2020); her salary includes stock/options; Glenmark: Other: Advisory board; Adicet bio: Other: Advisory board; Incyte: Other: Advisory board; Kite/Gilead: Other: Advisory board.

OffLabel Disclosure:
CAR T cells for CLL