DeVries, Todd

2537 Background: Orva-cel is a B-cell maturation antigen–targeted chimeric antigen receptor (CAR) T cell therapy being evaluated in the phase 1/2 EVOLVE study (NCT03430011) in pts with RRMM who had at least 3 prior lines of therapy (Tx). We previously reported safety and efficacy in the phase 1 study and established the recommended dose (RD) of orva-cel as 600 × 106 CAR+ T cells (Mailankody et al, ASCO 2020). Cytokine release syndrome (CRS), a dominant toxicity of CAR T cell therapy, is mediated in part by IL-1. We explore the role of ppx with AKR, an IL-1 signaling inhibitor, on reducing the incidence of grade (G) ≥2 CRS after orva-cel treatment at the RD. Methods: Fourteen pts were enrolled sequentially for AKR ppx and treated with orva-cel at the RD. The non-AKR ppx control group comprised the remainder of the phase 1 pts receiving orva-cel at the RD (n = 19). The median follow-up (range) was 3.0 mo (1.8–6.2) for the AKR ppx group and 8.8 mo (5.3–12.2) for the non-AKR ppx group. AKR was administered as 100 mg SC the night before orva-cel infusion, 3 h before the infusion (Day 1), and q24 h on Days 2–5. Dosing was increased to q12 h if CRS developed. CRS was graded by Lee (2014) criteria. Tocilizumab (T) and steroids (S) were used per protocol-specified treatment management guidelines. Results: Disease characteristics and outcomes are shown in the table. In AKR ppx and non-AKR ppx groups, median number of prior regimens was 6 and 5, and bridging Tx was used in 57% and 68% of pts, respectively. The total frequency of CRS was similar in the 2 groups, but with less G 2 in the AKR ppx pts; relative risk (95% CI) = 0.54 (0.21, 1.38). No G ≥3 CRS was seen in either group. The incidence of neurological events (NE), G ≥3 infection, and macrophage activation syndrome/hemophagocytic lymphohistiocytosis (MAS/HLH) was similar. T and S use was numerically lower with AKR ppx. Orva-cel expansion kinetics were similar in the 2 groups. All pts had a 2-month efficacy assessment, with ORR in 100% of AKR ppx and 95% of non–AKR ppx pts. Conclusions: In this nonrandomized evaluation of AKR ppx with orva-cel treatment, the incidence of G ≥2 CRS was lower in pts receiving AKR ppx. The use of AKR ppx produced no adverse effect on the incidence of NE, infection, or MAS/HLH, nor on orva-cel expansion or disease response. These results warrant further study of AKR ppx in CAR T cell therapy. Clinical trial information: NCT03430011. [Table: see text]

Abstract Background: Atacicept (TACI-Ig) is a recombinant fusion protein that inhibits BLyS (B lymphocyte stimulator) and APRIL (a proliferation-inducing ligand), cytokines that are involved in B-cell homeostasis and immunoglobulin (Ig) expression and are overexpressed in B-cell malignancies. In vitro, atacicept decreases the survival of lymphoma cells and in vivo, atacicept decreases serum immunoglobulin levels. Based on its effects on B cells, atacicept may offer a novel treatment for B-cell malignancies. Methods: A Phase 1, open-label, dose-escalation study of atacicept in patients with relapsed or refractory B-cell lymphoma was performed. Atacicept was administered subcutaneously for 5 weeks in single weekly doses of 2, 4, 7, or 10 mg/kg to sequential patient cohorts. After 8 weeks, patients with responding or stable disease were eligible for treatment on an extension study at the dose previously received for up to 24 weeks or until disease progression. The primary study objective was evaluation of overall safety and the maximum tolerated dose. Pharmacokinetics and biomarkers were also investigated. Results: As of July 2006, 15 patients with relapsed and refractory diffuse large B-cell lymphoma (7), follicular lymphoma (4), small lymphocytic lymphoma/chronic lymphocytic leukemia (2), and mantle-cell lymphoma (2) received 2, 4, or 7 mg/kg atacicept (4 patients per dose cohort) or 10 mg/kg atacicept (3 patients). All patients were heavily pretreated (median number of previous treatments was 5, range 1–10) and 4 patients had previously received a stem cell transplant. All patients completed study treatment (5 doses), except 2 who withdrew due to disease progression after receiving 2 and 4 doses. Atacicept was well tolerated at all doses. The most common adverse events (AEs) that occurred in ≥20% of patients were fatigue (47%) and injection site bruising (20%). Three AEs with ≥ grade 3 severity were reported for 1 patient including pain in jaw, gastrointestinal hemorrhage, and sepsis; all were considered unrelated to atacicept. Four SAEs considered unrelated to atacicept were reported for 2 patients who withdrew due to disease progression. Pharmacokinetic results were nonlinear and consistent with observations in other indications. Five weekly doses produced low to moderate accumulation of free total atacicept and atacicept/BLyS complex in serum. IgA, IgG, and IgM concentrations decreased in a dose-related pattern with a mean decrease of 15–40% from baseline after 4 weeks of atacicept. Peripheral B-cell numbers were variable and were difficult to evaluate due to low B-cell values at baseline in the majority of patients. At the 8-week evaluation, no objective responses were observed. Two patients had stable disease (1 with mantle cell lymphoma and 1 with follicular lymphoma) at 8 weeks, entered the extension study, and received additional doses of atacicept with no safety or tolerability concerns. Both patients however later discontinued treatment due to disease progression. Conclusion: Atacicept at doses of up to 10 mg/kg was well tolerated and demonstrated biological activity by decreasing Ig concentrations in this heavily pretreated cohort of patients with refractory B-cell lymphoma, although tumor responses were not observed.

Abstract Purpose: B-lymphocyte stimulator and a proliferation-inducing ligand regulate B-cell homeostasis and immunoglobulin production and are overexpressed in B-cell malignancies. Atacicept (TACI-Ig), a recombinant fusion protein that inhibits both B-lymphocyte stimulator and a proliferation-inducing ligand, may be a novel treatment for B-cell malignancies. Experimental Design: A phase 1, open-label, dose-escalation study of atacicept in patients with relapsed or refractory B-cell lymphoma was done. Atacicept was given s.c. weekly for 5 weeks to sequential patient cohorts at doses of 2, 4, 7, or 10 mg/kg. Patients responding or with stable disease were eligible for treatment on an extension study for up to 24 weeks or until disease progression. Results: All patients were heavily pretreated (median number of previous treatments, 5; range, 1-10), and four patients had previously received a stem cell transplant. Four patients were treated at the 2, 4, or 7 mg/kg dose levels, and three patients received 10 mg/kg of atacicept. Atacicept was well tolerated at all doses. Three adverse events with grade 3 severity were reported for one patient, including jaw pain, gastrointestinal hemorrhage, and sepsis; all were considered unrelated to atacicept. Pharmacokinetic results were nonlinear, and treatment with atacicept resulted in dose-dependent decreases in immunoglobulin concentrations. Two patients had stable disease at 8 weeks, entered the extension study, and received additional doses of atacicept with no safety or tolerability concerns. Conclusion: Atacicept at doses of up to 10 mg/kg was well tolerated and showed biological activity by decreasing immunoglobulin concentrations, although tumor responses were not observed.