Anti-CD19 chimeric antigen receptor T cells preceded by low-dose chemotherapy to induce remissions of advanced lymphoma.

Abstract

LBA3010 Background: T cells genetically-modified to express chimeric antigen receptors (CARs) targeting CD19 have potent activity against a variety of B-cell malignancies. Chemotherapy is administered prior to CAR T cells because depletion of recipient leukocytes enhances the anti-malignancy efficacy of adoptively-transferred T cells; an increase in serum interleukin (IL)-15 is one mechanism for this enhancement. Previously, we (Kochenderfer et al. Journal of Clinical Oncology, 2015) and others have reported patients treated with high-dose chemotherapy prior to anti-CD19 CAR T-cell infusions. This report describes treatment of 22 patients with low-dose conditioning chemotherapy followed by infusion of anti-CD19 CAR T-cells. Methods: Eighteen of 22 treated patients received 300 mg/m2 of cyclophosphamide (cy) daily for 3 days; 4 patients received 500 mg/m2 of cy on the same schedule. All patients received fludarabine 30 mg/m2daily for 3 days on the same days as cy. Patients received a single dose of CAR T cells 2 days after completion of chemotherapy. Blood CAR T cells and serum cytokines were analyzed in all patients. Results: Nineteen patients with various subtypes of diffuse large B-cell lymphoma (DLBCL) had the following responses: 8 CR, 5 PR, 2 SD, and 4 PD. One patient with mantle cell lymphoma obtained a CR. Two patients with follicular lymphoma both obtained CRs. Durations of response currently range from 1 to 20 months; 10 remissions are ongoing. All but 4 patients had either chemotherapy-refractory lymphoma or lymphoma that had relapsed after autologous stem cell transplant. The most prominent toxicities were various neurological toxicities. Other toxicities included fever and hypotension. The median peak blood CAR+ cell level was 47/μL (range 4-1217/μL). Patients obtaining CRs or PRs had higher peak blood CAR+ cell levels than patients experiencing SD or PD. The mean serum IL-15 level was 4 pg/mL before the conditioning chemotherapy and 32 pg/mL after chemotherapy (P < 0.0001). Conclusions: Anti-CD19 CAR T cells can induce remissions of advanced B-cell lymphoma when administered after low-dose chemotherapy. In the near future, CAR T cells will likely be a standard therapy for lymphoma. Clinical trial information: NCT00924326.