A Retrospective Study of Rabbit Anti-T Lymphocyte Globulin (rATLG) as a Second-Line Therapy in Transplant-Ineligible...

Severe aplastic anemia (SAA) is a potentially fatal disorder of bone marrow failure with a high risk of life-threatening infections and bleeding. While matched sibling donor transplantation remains the preferred therapy, immunosuppressive treatment with horse anti-thymocyte globulin (hATG), cyclosporine, and eltrombopag is the standard first-line option for non-transplant candidates. However, a significant proportion of patients fail to respond, and access to allogeneic transplantation is severely restricted in resource-limited settings due to prohibitive costs and infrastructure constraints. In such scenarios, rabbit anti-T lymphocyte globulin (rATLG) emerges as an important second-line salvage therapy.

This hospital-based retrospective study included 10 patients with SAA or very severe aplastic anemia (VSAA), aged ≥13 years, treated at King George's Medical University, Lucknow, between 2020 and 2024. All patients had relapsed or refractory disease following hATG and were ineligible for transplantation. rATLG was administered at 3.5 mg/kg/day for five days alongside cyclosporine and eltrombopag. Responses were assessed at three, six, and 12 months, with survival analysed using Kaplan-Meier (KM) estimates (censoring applied for patients alive or lost to follow-up at the last contact).

The cohort had a median age of 23 years, with 70% (7/10 patients) classified as SAA and 30% (3/10 patients) as VSAA. Four had refractory disease, six had relapsed disease, and three harboured a PNH clone. At 12 months, 40% (4/10 patients) achieved partial response; no complete responses were observed. Overall survival (OS) at two years was 78% (95% CI: 40.3-94.9) by KM estimate. The most common adverse events were fever, pruritus, hepatic dysfunction, and infections.

Although modest in efficacy, rATLG offers a clinically meaningful salvage option in transplant-ineligible SAA patients, particularly in low-resource settings where curative transplantation is often inaccessible. Our findings underscore the role of rATLG as a bridge therapy, while highlighting the urgent need for wider access to definitive curative options in developing countries.