CAR T Cells Show Encouraging Early Responses in Relapsed/Refractory B-Cell NHL

The second-generation 4-1BB bi-specific chimeric antigen receptor (CAR) T-cell therapy, C-CAR039, administered as treatment of patients with relapsed/refractory B-cell non-Hodgkin lymphoma (B-NHL), demonstrated improvement in response rates and had a favorable safety profile in a phase 1 study. The results were reported during the 2021 American Society of Clinical Oncology (ASCO) Annual Meeting.

“C-CAR039 has demonstrated a favorable safety profile and highly promising efficacy in patients with relapsed/refractory B-NHL,” Aibin Liang, MD, Tongji Hospital of Tongji University, Shanghai, China, said during an oral presentation of the data.

According to the safety data, 100% of patients experienced at least 1 adverse event (AE) of any grade.

In total, 92.9% of patients reported cytokine release syndrome (CRS); however, Liang noted, that most were grade 1 or 2 and all events were reversible. Only 1 patient, who was treated in the 2.5x106 CAR T cells/kg, experienced grade 3 CRS. The most common symptoms were pyrexia (100%) and hypotension (23.1%).

The median time to onset of CRS events was 2.5 days (range, 0-10), with a median time to resolution of 4 days (range, 1-25). CRS cases were treated with tocilizumab (14.3%), corticosteroids (3.6%), or a combination of the 2 (3.6%).

Two cases of neurologic events – both in the 5.0x106 CAR T cells/kg group – occurred at a median time of onset of 16 days (range, 4-28). The median time to resolution was 31.5 days (range, 11-52).

“CRS in higher dose groups showed shorter time to onset and longer resolution time,” Liang said.

Cytopenias were common, “mostly related to Cy/Flu lymphodepletion and are reversible,” he added, noting that infection was also common, occurring in 53.6% of patients, with only 1 grade 3 event.

The most common grade 3 or higher AEs included lymphopenia (96.$%), leukopenia (89.3%), neutropenia (89.3%), anemia (32.1%), and thrombocytopenia (25%).

For efficacy, median follow-up was 7 months (range, 1.9-17.2).

The overall response rate (ORR) was 92.6% for the entire population, including an 85.2% complete response (CR) rate, 7.4% partial response (PR) rate, 3.7% with stable disease (SD), and 3.7% with progressive disease (PD). Broken down by disease subtype, ORR in those with diffuse large B-Cell Lymphoma (DLBCL), primary mediastinal B-cell lymphoma (PMBCL), follicular lymphoma (FL), and tFL were 91.7% (CR, 83.3%; PR, 8.3%), 100% (CR, 100%), 100% (CR, 100%), and 100% (CR, 100%), respectively. Liang noted that the CR rate was consistent among key subgroups, including dose level, disease type, cell or origin of cancer, age, sex, stage, IPI, double expressors, extranodal disease, prior lines of therapy, previous response status, previous ASCT, and bridging treatment.

The median time to first response was 1 month (range, 0.9-1.6), as was median time to CR (range, 0.9-6.0). Four patients relapsed at 3, 6, 8, and 9 months, respectively, after achieving CR. Median duration of response (DOR) has not been reached. The 6-month progression-free survival (PFS) was 83.2% (95% CI, 69.1-100).

“C-CAR039 proliferation and expansion in the peripheral blood correlated with B cell depletion,” Liang added.

C-CAR039 – a novel second generation 4-1BB bi-specific CAR T-cell therapy that targets both CD19 and cd20 antigens – has demonstrated in vitro anti-tumor activity against both single- and double-positive CD20/CD19-expressing tumors, as well as superior anti-tumor activity in both in vitro and in vivo to the bi-specific CAR T-cell therapy with the tandem linked scFvs of Leu16 and FMC63, Liang explained.

“This data strongly support moving this CAR design to clinic use as the lead asset,” he added.

Manufacturing the CAR T-cell therapy was carried out in a functionally closed, highly automated serum free system within a median of 6 days (range, 5-11). Median vein-to-vein time was 19 days (range, 12-67).

Dose escalation and expansion studies were conducted to evaluate the safety and efficacy of C-CAR039 in r/r B-NHL patients. C-CAR039 was administered as a single intravenous dose after a 3-day cyclophosphamide plus fludarabine conditioning regimen.

The phase 1 study is an open-label, dose escalation and expansion study conducted across 4 sites in China – designed to evaluate the safety and efficacy of this approach in patients with relapsed/refractory B-NHL.

Investigators administered C-CAR039 as a single intravenous dose after a 3-day cyclophosphamide plus fludarabine conditioning regimen.

Eligibility criteria included patients aged 18 to 75 years; relapsed/refractory B-NHL, including DLBCL, FL, and mantle cell lymphoma (MCL); either CD19- or CD20-positive disease; no active central nervous system (CNS) involvement; and have received anti-CD20 monoclonal antibodies.

The safety assessment included the incidence and severity of treatment-emergent adverse events (TRAEs), while the efficacy assessment was comprised of ORR, DOR, PFS, and OS.

In the trial, patients were treated across 3 doses: 1.0x106 CAR T cells/kg (DL1), 2.5x106 CAR T cells/kg (DL2), and 5.0x106 CAR T cells/kg (DL3).

As of April 20, 2021, 34 patients were infused with C-CAR039. In total, 28 were evaluable for safety, including 4 in the DL1 arm, 15 in the DL2 arm, and 9 in the DL3 arm; while 27 were evaluable for efficacy, including 4 in the DL1 arm, 15 in the DL2 arm, and 8 in the DL3 arm.

Median age was 55.5 years (range, 28-71). The majority of patients were male (89.3%), had diffuse large B-cell lymphoma (89.3%), an ECOG performance score of 0 (64.3%), and were Ann Arbor stage III/IV (75%). Moreover, 8 patients (28.6%) had double-expressor lymphoma.

The median number of prior lines of therapy was 3 (range, 1-5), including ASCT (17.9%), a BTK inhibitor (28.6%), and lenalidomide (Revlimid; 32.1%). Eight patients (28.6%) had never experienced a CR to prior therapies and 5 patients (17.9%) received bridging therapy.

“The early clinical efficacy signal is encouraging and compares favorably to anti-CD19 CAR T and peer therapies,” the study authors concluded. “These findings will be evaluated in more patients with longer follow-up to confirm safety, efficacy and duration of response.”

_Reference:

_{Liang A, Zhou L, Li P, et al. Safety and efficacy of a novel anti-CD20/CD19 bi-specific CAR T-cell therapy (C-CAR039) in relapsed or refractory (r/r) B-cell non-Hodgkin lymphoma (B-NHL). J Clin Oncol. 2021;39:suppl 15; abstr 2507. doi: 10.1200/JCO.2021.39.15_suppl.2507.}