David Hagerty

Rational Development of LEA29Y (belatacept), a High‐Affinity Variant of CTLA4‐Ig with Potent Immunosuppressive Properties

Current success in organ transplantation is dependent upon the use of calcineurin‐inhibitor‐based immunosuppressive regimens. Unfortunately, current immunotherapy targets molecules with ubiquitous expression resulting in devastating non‐immune side effects. T‐cell costimulation has been identified as a new potential immunosuppressive target. The best characterized pathway includes CD28, its homologue CTLA4 and their ligands CD80 and CD86. While an immunoglobulin fusion protein construct of CTLA4 suppressed rejection in rodents, it lacked efficacy in primate transplant models. In an attempt to increase the biologic potency of the parent molecule a novel, modified version of CTLA4‐Ig, LEA29Y (belatacept), was constructed. Two amino acid substitutions (L104E and A29Y) gave rise to slower dissociation rates for both CD86 and CD80. The increased avidity resulted in a 10‐fold increase in potency in vitro and significant prolongation of renal allograft survival in a pre‐clinical primate model. The use of immunoselective biologics may provide effective maintenance immunosuppression while avoiding the collateral toxicities associated with conventional immunsuppressants.

Rituximab inhibits structural joint damage in patients with rheumatoid arthritis with an inadequate response to tumour necrosis factor inhibitor therapies

OBJECTIVE To determine if treatment with a B cell-targeted therapy can inhibit the progression of structural joint damage in patients with rheumatoid arthritis (RA), exhibiting an inadequate response to tumour necrosis factor (TNF) inhibitors. METHODS In this phase III study, patients with an inadequate response to a TNF inhibitor and receiving methotrexate were randomised to rituximab or placebo. Radiographs were obtained at baseline, week 24 and week 56 after randomisation. Patients with an inadequate response to their randomised therapy could receive rescue medication from week 16. From week 24, eligible patients from both treatment arms could receive open-label rituximab. Patients were analysed according to their original treatment group. Radiographs were scored using the Genant-modified Sharp method. The primary radiographic endpoint was change in total Genant-modified Sharp score at week 56. RESULTS Rituximab treatment caused significant reduction in joint damage progression compared with placebo. The mean change from baseline in the total Genant-modified Sharp score at week 56 was significantly lower for patients treated with rituximab than for patients treated with placebo (1.00 vs 2.31; p = 0.005), and was supported by changes in erosion score (0.59 and 1.32 for rituximab plus methotrexate vs placebo plus methotrexate, respectively; p = 0.011) and joint space narrowing score (0.41 and 0.99, respectively; p<0.001). CONCLUSIONS This study provides the first evidence that a B cell-targeted therapy-rituximab-can significantly inhibit the progression of structural joint damage in patients with RA with long-standing, active and treatment-resistant disease.

Development of a Chimeric Anti-CD40 Monoclonal Antibody That Synergizes with LEA29Y to Prolong Islet Allograft Survival

In recent years, reagents have been developed that specifically target signals critical for effective T cell activation and function. Manipulation of the CD28/CD80/86 and CD40/CD154 pathways has exhibited extraordinary efficacy, particularly when the pathways are blocked simultaneously. Despite the reported efficacy of anti-CD154 in rodents and higher models, its future clinical use is uncertain due to reported thromboembolic events in clinical trials. To circumvent this potential complication, we developed and evaluated a chimeric Ab targeting CD40 (Chi220, BMS-224819) as an alternative to CD154. Although Chi220 blocks CD154 binding, it also possesses partial agonist properties and weak stimulatory potential. The anti-CD40 was tested alone and in combination with a rationally designed, high affinity variant of CTLA4-Ig, LEA29Y (belatacept), in a nonhuman primate model of islet transplantation. Although either agent alone only modestly prolonged islet survival (Chi220 alone: 14, 16, and 84 days; LEA29Y alone: 58 and 60 days), their combination (LEA29Y and Chi220) dramatically facilitated long term survival (237, 237, 220, >185, and 172 days). We found that the effects of Chi220 treatment were not mediated solely through deletion of CD20-bearing cells and that the combined therapy did not significantly impair established antiviral immunity.

Continued inhibition of structural damage over 2 years in patients with rheumatoid arthritis treated with rituximab in combination with methotrexate

Background Rituximab inhibited structural damage at 1 year in patients with rheumatoid arthritis (RA) who had had a previous inadequate response to tumour necrosis factor (TNF) inhibitors. Objective To assess structural damage progression through 2 years. Methods Intention-to-treat patients with one post-baseline radiograph (rituximab n=281; placebo n=187) received background methotrexate (MTX) and were randomised to rituximab (2×1000 mg infusions, 2 weeks apart) or placebo; patients were eligible for rituximab re-treatment every 6 months. By week 104, 82% of the placebo population had received ≥1 dose of rituximab. Radiographic end points included the change in total Sharp score (TSS), erosion and joint space narrowing scores at week 104. Results At week 104, significantly lower changes in TSS (1.14 vs 2.81; p<0.0001), erosion score (0.72 vs 1.80; p<0.0001) and joint space narrowing scores (0.42 vs 1.00; p<0.0009) were observed with rituximab plus MTX vs placebo plus MTX. Within the rituximab group, 87% who had no progression of joint damage at 1 year remained non-progressive at 2 years. Conclusions Rituximab plus MTX demonstrated significant and sustained effects on joint damage progression in patients with RA and a previously inadequate response to TNF inhibitors.