Humanized CD19-Targeted Chimeric Antigen Receptor (CAR) T Cells in CAR-Naive and CAR-Exposed Children and Young Adults With Relapsed or Refractory Acute Lymphoblastic Leukemia

Abstract

Purpose: CD19-targeted chimeric antigen receptor (CAR)-modified T cells demonstrate unprecedented responses in B-cell acute lymphoblastic leukemia (B-ALL); however, relapse remains a substantial challenge. Short CAR T-cell persistence contributes to this risk; therefore, strategies to improve persistence are needed.

Methods: We conducted a pilot clinical trial of a humanized CD19 CAR T-cell product (huCART19) in children and young adults with relapsed or refractory B-ALL (n = 72) or B-lymphoblastic lymphoma (n = 2), treated in two cohorts: with (retreatment, n = 33) or without (CAR-naive, n = 41) prior CAR exposure. Patients were monitored for toxicity, response, and persistence of huCART19.

Results: Seventy-four patients 1-29 years of age received huCART19. Cytokine release syndrome developed in 62 (84%) patients and was grade 4 in five (6.8%). Neurologic toxicities were reported in 29 (39%), three (4%) grade 3 or 4, and fully resolved in all cases. The overall response rate at 1 month after infusion was 98% (100% in B-ALL) in the CAR-naive cohort and 64% in the retreatment cohort. At 6 months, the probability of losing huCART19 persistence was 27% (95% CI, 14 to 41) for CAR-naive and 48% (95% CI, 30 to 64) for retreatment patients, whereas the incidence of B-cell recovery was 15% (95% CI, 6 to 28) and 58% (95% CI, 33 to 77), respectively. Relapse-free survival at 12 and 24 months, respectively, was 84% (95% CI, 72 to 97) and 74% (95% CI, 60 to 90) in CAR-naive and 74% (95% CI, 56 to 97) and 58% (95% CI, 37 to 90) in retreatment cohorts.

Conclusion: HuCART19 achieved durable remissions with long-term persistence in children and young adults with relapsed or refractory B-ALL, including after failure of prior CAR T-cell therapy.

Trial registration: ClinicalTrials.gov NCT02374333.

Conflict of interest statement

David M. BarrettTravel, Accommodations, Expenses: Therakos David T. TeacheyConsulting or Advisory Role: SobiResearch Funding: Novartis, Beam Therapeutics, NeoImmuneTech Colleen CallahanConsulting or Advisory Role: NovartisSpeakers' Bureau: Peerview Susan R. RheingoldEmployment: OptiNoseStock and Other Ownership Interests: OptiNoseConsulting or Advisory Role: PfizerResearch Funding: Pfizer Richard AplencExpert Testimony: Vorys Pamela A. ShawPatents, Royalties, Other Intellectual Property: I am part of a patent owned by UPenn and currently licensed to Novartis for an algorithm that predicts severe cytokine release syndrome for the CART 19 therapy. I receive 10% of the licensing fees Edward PequignotPatents, Royalties, Other Intellectual Property: As part of Penn's role in the FDA-approval of CAR-T therapy, and for my part as an employee of Penn involved in their research in CAR-T, I have received royalties of approximately $300 in US dollars over the past 2 years Jennifer L. BrogdonEmployment: Novartis Institutes for BioMedical ResearchStock and Other Ownership Interests: Novartis Institutes for BioMedical Research Donald L. SiegelResearch Funding: Tmunity Therapeutics IncPatents, Royalties, Other Intellectual Property: A patent, owned by the Trustees of the University of Pennsylvania, on which I am listed as an inventor is licensed to Alexion Pharmaceuticals. I receive royalties as stipulated in the University of Pennsylvania Faculty HandbookExpert Testimony: Regeneron Megan M. DavisLeadership: Cellares CorporationConsulting or Advisory Role: Tmunity Therapeutics IncResearch Funding: Tmunity Therapeutics IncPatents, Royalties, Other Intellectual Property: Novartis Institutes for Biomedical Research—royalties and milestones for patents/knowhow, Tmunity Therapeutics—royalties andmilestones from patents/knowhow Simon F. LaceyConsulting or Advisory Role: Gilead SciencesResearch Funding: Tmunity Therapeutics Inc, Cabaletta Bio, Novartis Institutes for BioMedical ResearchPatents, Royalties, Other Intellectual Property: Patents and IP related to CTL019 (Kymriah) assigned by the University of Pennsylvania to Novartis Elizabeth O. HexnerConsulting or Advisory Role: Blueprint Medicines, ABIM Subspecialty BoardResearch Funding: Blueprint Medicines, Tmunity Therapeutics Inc Gerald B. WertheimEmployment: Johnson & JohnsonStock and Other Ownership Interests: Johnson & Johnson Bruce L. LevineStock and Other Ownership Interests: Tmunity Therapeutics IncHonoraria: Novartis, TerumoConsulting or Advisory Role: Avectas, Ori Biotech, Vycellix, Immuneel Therapeutics, In8bio, Patheon/ThermoFisher Viral Vector ServicesResearch Funding: Tmunity Therapeutics IncPatents, Royalties, Other Intellectual Property: Intellectual property and patents in the field of cell and gene therapyTravel, Accommodations, Expenses: Avectas, Terumo Carl H. JuneLeadership: AC ImmuneStock and Other Ownership Interests: Celldex, Tmunity Therapeutics Inc, Cabaletta Bio, Carisma Therapeutics, DeCART Therapeutics, Bluesphere Bio, Cellares, ZIOPHARM Oncology, Decheng Capital, Posieda Therapeutics, VerismaHonoraria: PfizerConsulting or Advisory Role: Celldex, Viracta Therapeutics, Cabaletta Bio, Carisma Therapeutics, Kiadis Pharma, WIRB-Copernicus Group, Janssen OncologyResearch Funding: Novartis, Tmunity Therapeutics IncPatents, Royalties, Other Intellectual Property: IP licensed to Novartis; Royalties paid to University of Pennsylvania, Office of Naval Research; IP and patent royalties, IP licensed to Tmunity Stephan A. GruppConsulting or Advisory Role: Novartis, Jazz Pharmaceuticals, Janssen, Cellular Biomedicine Group, TCR2 Therapeutics, Humanigen, Roche, Adaptimmune, Alimera Sciences, Cabaletta Bio, CRISPR Therapeutics/VertexResearch Funding: Novartis, Kite/Gilead, Servier, Jazz Pharmaceuticals, VertexPatents, Royalties, Other Intellectual Property: UPenn Toxicity management patentExpert Testimony: Juno Therapeutics Shannon L. MaudeConsulting or Advisory Role: Novartis, Wugen IncResearch Funding: NovartisTravel, Accommodations, Expenses: Novartis, Kite, a Gilead company, Wugen IncNo other potential conflicts of interest were reported.

Figures

FIG 1.

CONSORT diagram. In addition to the excluded patients detailed, a repeat manufacture attempt failed because of poor cell growth for a patient with a CD19+ relapse after initial treatment with huCART19 in the retreatment cohort. CAR, chimeric antigen receptor; huCART19, humanized CD19 CAR T-cell product.

FIG 2.

RFS, EFS, and OS. (A) RFS by cohort, defined as the time from onset of remission to relapse in the patients who achieved a complete response. Data were censored for allogeneic hematopoietic stem-cell transplant (CAR-naive, n = 4; retreatment, n = 1) or other alternative therapy during remission (CAR-naive, n = 2; retreatment, n = 4). (B) EFS by cohort, defined as the time from huCART19 infusion to the earliest of the following events: no response (CAR-naive, n = 1; retreatment, n = 12), relapse after achieving a complete response (CAR naive, n = 12; retreatment, n = 8), or development of a subsequent malignancy (retreatment, n = 1). Data were censored for alternative therapy or allogeneic hematopoietic stem-cell transplant during remission. (C) OS by cohort, defined as the time from huCART19 to date of death from any cause. Seven CAR-naive and 14 retreatment patients died during the follow-up period. Tick marks indicate the time of censoring. CAR, chimeric antigen receptor; EFS, event-free survival; huCART19, humanized CD19 CAR T-cell product; OS, overall survival; RFS, relapse-free survival.

FIG 3.

Persistence of huCART19. (A and B) Cumulative incidence curves of the time to the first confirmed negative measurement of huCART19 in the (A) CAR-naive and (B) retreatment cohorts, as measured by flow cytometry, in the peripheral blood and bone marrow. Confirmed negative was defined as two consecutive measurements

FIG 4.

Effect of BCR on RFS. RFS, defined as the time from onset of remission to relapse in the patients who achieved a complete response, in CAR-naive patients, with BCR treated as a time-varying covariate. BCR, B-cell recovery; CAR, chimeric antigen receptor; RFS, relapse-free survival.