Late Effects of CD19-Targeted CAR-T Cell Therapy
Authors: Cordeiro Ana , Bezerra Evandro D , Hill Joshua Aiden , Turtle Cameron J. , Maloney David G. , Bar Merav 
Published: October 2019

Recently two CD19-targeted CAR-T cell products were approved by the FDA for treatment of relapsed/refractory (R/R) acute lymphoblastic leukemia (ALL) and non-Hodgkin lymphoma (NHL). Excellent anti-tumor activity has been observed in patients with B cell malignancies. However, data regarding long-term effects of this therapy are very limited.

Here we report long-term effects in 59 patients (pts) with R/R NHL and chronic lymphocytic leukemia (CLL) who received a total of 85 CD19-targeted CAR-T cell infusions on a clinical trial in our institution (NCT01865617), survived more than a year, and had at least one year follow-up data after their first CAR-T cell infusion. One patient who survived more than a year was excluded from this report due to incomplete data. Median follow-up was 23 months (range, 13-57) after the first CAR-T cell infusion. We report adverse events that occurred or persisted beyond 90 days after the last CAR-T cell infusion, excluding events related to disease progression.

Median age at CAR-T cell infusion was 60 years (range, 34-73). There were 42 (71%) pts with NHL and 17 (29%) with CLL. The median number of prior lines of treatment was 4 (range, 1-8). 23 (39%) pts had received prior autologous (auto) hematopoietic cell transplantation (HCT), and 9 (15%) pts had received prior allogeneic (allo) HCT. 35 (59%) pts received one CAR-T cell infusion, 22 (37%) pts received 2 infusions, and 2 (3%) pts received 3 infusions. 3 (5%) pts received a maximum cell dose of 2x10(5)/kg, 40 (68%) pts received a maximum cell dose of 2x10(6)/kg, and 16 (27%) pts received a maximum cell dose of 2x10(7)/kg. 65 (76%) infusions were preceded by cyclophosphamide and fludarabine. CRS grade I/II occurred in 38 (64%) pts, and grade III in 4 (7%) pts (graded per Lee et al. Blood, 2014). No grade IV CRS was reported in this cohort. Acute neurotoxicity occurred in 20 (34%) pts.

At 2 months after CAR-T cell infusion complete response (CR) was documented in 34 (58%) pts, partial response (PR) in 12 (20%) pts, and disease progression (PD) in 13 (22%) pts. During the follow-up period, another 15 (25%) pts developed PD. 29 (49%) pts received salvage therapy after CAR-T cell infusion, 8 (14%) of them received allo HCT. 5 (8%) pts received allo HCT as consolidation after CAR-T cell.

5 of 25 (20%) pts who did not receive additional therapy after last CAR-T cell infusion experienced ongoing cytopenias requiring G-CSF support, or RBC or platelet transfusions, beyond 90 days after last CAR-T cells infusion.

8 (14%) pts were diagnosed with subsequent malignancies, including 3 (5%) myelodysplasia, 4 (7%) non-melanoma skin cancer, and 1 non-invasive bladder cancer. All, but 1 patient with skin cancer, had auto or allo HCT before CAR-T cell therapy. Neuropsychiatric disorders were documented in 5 (8%) pts; including major depression, suicidal attempt, myoclonic seizures, and TIA. 5 (8%) pts experienced cardiovascular events. 4 (7%) pts developed renal dysfunction. 3 (5%) pts developed respiratory disorders. One pt had gastrointestinal bleeding. Of the 9 pts who had undergone allo HCT before CAR-T cell therapy, 1 pt (11%) developed GVHD flare.

Severe hypogammaglobulinemia (IgG &lt; 400 mg/dL) or IgG replacement beyond day 90 after last CAR-T cell infusion (and before HCT if was done) were documented in 24 (41%) pts.

54 pts were included in the infection analysis. 178 suspected infection events beyond day 90 after last CAR-T cell infusion were documented in 40 (74%) pts. Antimicrobial treatments were documented for 124 infection events. 44 (25%) of the events were microbiologically proven. The most common infections were upper (92) and lower (29) respiratory tract infections. 25 (46%) pts required hospital admission due to infections, of them 8 (15%) were admitted to the ICU. When excluding infections that occurred after salvage therapy following CAR-T cell, we identified 117 infections in 28 (52%) pts.

3 pts died of non-relapse causes (2 due to infection after allo HCT, and 1 due to duodenal ulcer and gut perforation).

In conclusion, our data suggest that long-term effects of CD19-targeted CAR-T cell therapy are acceptable. Most effects identified in our cohort were not severe, and many may have been related to prior or subsequent therapies (e.g. HCT before or after CAR-T cell therapy, or subsequent salvage treatments). Our data is consistent with recent published data demonstrating excellent long-term disease outcome for this heavily pre-treated population.

Disclosures

Turtle: Juno/Celgene: Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; Nektar Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Precision Biosciences: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Eureka Therapeutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Caribu Biosciences: Membership on an entity's Board of Directors or advisory committees. Maloney:Juno Therapeutics: Research Funding; GlaxoSmithKline: Research Funding; Janssen Scientific Affairs: Honoraria; Roche/Genentech: Honoraria; Seattle Genetics: Honoraria.