Results of a Phase III Double-Blind Study of the Addition of Tocilizumab Vs. Placebo to Cyclosporin/Methotrexate Gvhd Prophylaxis after HLA-Matched Allogeneic Stem Cell Transplantation

Abstract

Background: IL-6 mediates graft-vs.-host disease (GVHD) in experimental models of allogeneic stem cell transplantation. The addition of a humanized anti-IL-6R mAb (Tocilizumab; TCZ) to standard GVHD prophylaxis has shown in promise in reducing the incidence of acute GVHD in two prospective phase I/II clinical studies. Aims: To determine the efficacy of TCZ in preventing grade II-IV acute GVHD in patients with acute leukaemia or myelodysplasia undertaking 8/8 matched related sibling (MSD) or matched unrelated donor (MUD) allogeneic HPCT after myeloablative (MAC) or reduced intensity conditioning (RIC) across five Australian transplant centers. Methods: 145 patients (50 MSD and 95 MUD) were randomly assigned to either placebo or TCZ (8mg/kg; max dose 800mg) on day-1 of conditioning. Patients and physicians were both blinded to treatment. RIC patients all received Flu/Mel (n=81, 56%) while MAC patients received Cy/TBI (n=46, 32%) or Bu/Cy (n=18, 12%). All patients received T-replete PBPC grafts, and standard GVHD prophylaxis cyclosporine and day 1 (15mg/m2), 3, 6 and 11 (10mg/m2) methotrexate. The primary endpoint was incidence of grade II-IV acute GVHD. A planned substudy analyzed the MUD cohort. Secondary endpoints included day 180 grade II-IV acute GVHD free-survival (GVHD-FS), transplant-related mortality (TRM), progression-free survival (PFS), overall survival (OS), time to engraftment and rates of infection. The study was powered to observe a 50% reduction in the incidence of grade II-IV acute GVHD at day +100 for the entire and MUD cohorts, assuming a 50-55% baseline in the control group. Competing risk (death) regression adjusted hazard ratio (HR) was estimated to evaluate the GVHD-related outcomes in TCZ vs. placebo groups. Results: With a median follow up of 746 days, the overall incidence of grade II-IV GVHD at day 100 for the entire cohort was 36% vs. 27% for placebo vs. TCZ respectively (HR: 0.69; 95% CI 0.38-1.26; p=0.23), and 45% vs. 32% (HR: 0.61; 95% CI 0.31-1.22; p=0.16) for the MUD subgroup. The incidence of grade II-IV GVHD at day 180 for the entire cohort was 40% vs. 29% for placebo vs. TCZ respectively (HR: 0.68; 95% CI 0.38-1.22; p=0.19), and 48% vs. 32% (HR: 0.59; 95% CI 0.30-1.16; p=0.13) for the MUD subgroup. The incidence of severe grade III/IV GVHD at day 100 for the entire cohort was similar, 13% vs. 14% for placebo vs. TCZ respectively (HR: 1.04; 95% CI 0.42-2.61; p=0.93), and 10% vs. 14% for the MUD subgroup (HR: 1.42; 95% CI 0.41-4.95; p=0.59). A trend to improved GVHD-FS was noted in the TCZ-treated MUD subgroup, 52% vs. 68% for placebo vs. TCZ treated (HR: 1.70; 95% CI 0.86-3.37; p=0.13). For the entire cohort, TRM occurred in 8% of placebo-treated vs. 11% of TCZ-treated patients respectively (HR: 1.37; 95% CI 0.48-3.96; p=0.56); Progressions were similar at 25% vs. 33% (HR:1.44; CI 0.78-2.63, p=0.24) and OS was 79% vs. 71% (HR: 0.69; CI 0.35-1.34, p=0.27). No significant differences were seen in these outcomes in the MUD cohort. Day to neutrophil engraftment was marginally delayed in TCZ-treated patients, with median time to neutrophil ≥0.5 of 15 days (range 11-24 days) vs. 18 days (range 9-35 days) for placebo vs. TCZ-treated patients respectively (95% CI 1.3-4.7; p=0.001). Time to platelet engraftment was also marginally delayed in TCZ-treated patients, with median time to plts≥20 of 16 days (range 9-36 days) vs. 19 days (range 11-389 days) (95% CI 0.4-5.6; p=0.022). The median time to neutrophil and platelet engraftment in TCZ-treated patients were each 2 days slower in the MUD cohort (p=0.016 and p=0.22 for neutrophils and plts respectively). Two TCZ-treated patients died beyond day 30 (at day 31 and 32) with incomplete neutrophil recovery. The incidence of 1 or more grade 3 or higher liver toxicity (LT) was similar between groups, occurring in 14% of placebo-treated patients vs. 15% of TCZ-treated patients respectively (OR: 1.14; 95% CI 0.45-2.88; p=0.79). Grade 2 or higher infection adverse events occurred in 64% of placebo-treated patients vs. 71% of TCZ-treated patients respectively (OR: 1.34; 95% CI 0.67-2.71; p=0.41). Conclusion: In a phase III randomized, double-blind trial, TCZ administered at D-1 showed non-significant trends to reduced incidence of grade II-IV GVHD and improved acute GVHD-free survival in recipients of HLA-matched MUD donors, but no improvements in long term-survival. Study power was compromised by lower rates of acute GVHD in the control group than anticipated. Disclosures Ritchie: Novartis: Honoraria; Amgen: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy; BMS: Research Funding; Takeda: Research Funding; Beigene: Research Funding; Imago: Research Funding; Sanofi: Honoraria. Gottlieb:Novartis: Consultancy; AbbVie: Consultancy; University of Sydney: Employment; Merck: Consultancy; Gilead: Consultancy; Haemalogix P/L: Membership on an entity's Board of Directors or advisory committees, Research Funding. Paul:Novo Nordisk: Consultancy, Research Funding; Sanofi: Consultancy, Speakers Bureau; Roche: Consultancy, Research Funding; AstraZeneca: Consultancy, Research Funding, Speakers Bureau. Hill:Roche: Other: Investigator driven trial funding; Pharamcyclics: Consultancy, Research Funding; CSL: Consultancy, Research Funding; Implicit Bioscience: Consultancy, Research Funding. OffLabel Disclosure: Use of Tocilizumab for the prevention of acute GVHD

Targeting Signal 3 Extracellularly and Intracellularly in Graft-Versus-Host Disease

“…A phase II trial in which patients received busulfan-based conditioning prior to receiving tocilizumab with tacrolimus and methotrexate showed a low incidence of gastrointestinal GVHD (38). Recently, a phase III randomized and double-blinded trial observed a trend toward a reduced overall incidence of grade II-IV GVHD in patients receiving tocilizumab, but no difference in long term survival compared to controls (39).…”

GVHD Prophylaxis 2020

“…It is logical that inhibiting the very movement of effector T-lymphocytes to target organs should better prevent GVHD rather than trying to arrest the widespread inflammation and cytokine cascades which characterize the final common pathway in GVHD pathogenesis. As a testimony to that, when tocilizumab an IL-6 blocker was evaluated, despite promising phase II single-arm data, was not more effective than standard prophylaxis in a phase III RCT ( 71 ). This has in fact been the case with numerous promising prophylactic therapies which perform well in single-arm studies but have not been a home run in well-designed phase III studies.…”

“…Therefore, IL-6 blocking agents could prevent aGVHD. In a phase II trial, tocilizumab, a humanized monoclonal antibody against the IL-6 receptor (IL-6R) was found to be promising ( 70 ); however, in a placebo-controlled phase III study from Australia, there was no significant difference in grades II-IV or III-IV aGVHD ( 71 ). This is a salient reminder that given the complex pathophysiology of aGVHD, with crosstalk between myriad cytokines and immune effector cells, targeting multiple cytokine pathways will be required for efficacy.…”

Translational and clinical advances in acute graft-versus-host disease

“…Based on promising phase II data, 79 a placebo-controlled phase III study from Australia was reported, which, however, showed no significant difference in grades II-IV or III-IV aGvHD. 80 This is a salient reminder that, given the complex pathophysiology of aGvHD, with crosstalk between myriad cytokines and immune effector cells, it is possible that targeting multiple cytokine pathways will be required for efficacy.…”