Combined Cytokine Blocking Therapy (CCBT) Using Basiliximab and Infliximab for Treatment of Steroid-Refractory Graft Versus Host Disease (SR-GvHD)

Background

Despite improved advances in graft-vs-host disease (GvHD) prophylaxis regimens and post-allogeneic hematopoietic cell transplant (HCT) supportive care, clinically significant acute GvHD still develops in approximately 30-50% of HCT recipients (Lazaryan A et al. BMT 2016) and often results in increased transplanted-related morbidity and mortality and deterioration of quality of life (Choi J et al. Blood 2012). Standard first-line treatment is high-dose glucocorticoids have been limited including recently approved JAK2 inhibitor (ruxolitinib). The utilization of combined cytokine blockade therapy (CCBT) with the monoclonal antibodies infliximab (a TNF-α inhibitor, INF) and basiliximab (an IL-2 receptor blocker, BAS), has had limited discussion in the literature despite common utilization. The primary objective of this retrospective study was to determine overall response rate (ORR) at days 7, 14 and 28 for CCBT. Secondary outcomes included non-relapse mortality (NRM), and overall survival (OS).

Methods

60 patients who met the inclusion criteria were analyzed. Patients included were ≥18 years old and had undergone HCT using any donor or graft source with any conditioning regimen between 2010-2021 at City of Hope Medical Center in Duarte, CA. Patients had steroid refractory aGvHD, according to Mount Sinai Consortium guidelines (Harris AC et al. BMT 2016) and received at least one dose of BAS and at least one dose of INF. Patients with >1 allogeneic transplant, chronic GVHD including overlap syndrome, relapse of primary disease, graft loss, and glucocorticoid treatment for indications other than GVHD were excluded.

Treatment

BAS was administered intravenously as 20mg doses given first as loading doses on days 1 and 4. Subsequent doses were given weekly starting 7 days after the final loading dose (day 4). INF was administered as 10 mg/kg doses infused weekly. Tacrolimus, sirolimus and cyclosporine dosing and monitoring were performed in accordance with institutional policies. All patients had clinical presentation of SR-GVHD defined as ≥1 of the following: GVHD increasing in stage in any organ or developing in a new organ after 3 days of ≥2 mg/kg methylprednisolone (MSPE) or equivalent, GVHD that has not improved in stage in ≥1 organ after 7 days of ≥2 mg/kg MSPE or equivalent, development of GVHD in a new organ after ≥1 mg/kg MSPE or equivalent for skin GVHD or patients who progress during tapering before a 50% decrease in glucocorticoids is achieved.

Results

The median age was 53 years (range, 5-78) at time of HCT. Of 60 patients, 65% were males and with 18.3% of male patients receiving grafts from female donor. HCT-CI at the time of HCT was 3 or more in 47% of the patients. Conditioning for those patients was ablative in 43.3% of patients with 76.7% of patients receiving PBSC grafts from mostly MSD/MUD in 75% of patients. Most patients had grade 3 or 4 overall acute GVHD (grade 3: n=35, 58.3%, grade 4: n=20, 33.3%). Median time to start of BAS after start of steroid was 7 days while time to start of INF after steroid was 11 days. Ruxolitinib was initiated in 33.3% (20/60) of patients prior to CCBT. ORR for CCBT therapy at day 7, 14, and 28 were 28.3% (17/60; CR 5.0%), 38.3% (23/60; CR 11.7%), and 38.3% (23/60; CR 23.3%), respectively. Patients who received ruxolitinib prior to CCBT had lower ORR (25%) compared to those who did not (47.5%).

37 patients died-20 of aGVHD, 4 of infection, 1 of sudden cardiac death and 1 of leukemia relapse. OS was 41.7% at 6 months and 36.5% at 12 months (Figure 1A). Cumulative incidence of NRM was 51.7% at 6 months and 55% at 12 months (Figure 1B). Cumulative incidence of any cGvHD was 33.6% at 12 months while it was 30% for extensive cGvHD at the same 12-month interval. In patients with and without ruxolitinib initiated prior to CCBT, OS at 12 months was 30% vs 40%, respectively (Figure 2A) while NRM at 12 months was 65% and 50%, respectively (Figure 2B).

Conclusion

CCBT has potential efficacy in steroid refractory aGVHD. The observed ORR is reflective of both advanced and highly refractory aGVHD with one-third of patients progressing on ruxolitinib. Given the favorable observed ORR in this difficult to treat population, CCBT is a potentially promising approach and suitable alternative in the second line or as salvage therapy in patients failing Ruxolitinib.