Subcutaneous Alemtuzumab Is Safe and Effective for Treatment of Global or Single-Lineage Immune-Mediated Marrow Failure: A Pilot Study.

Acquired marrow failure syndromes may globally affect all hematopoietic lineages, as in severe aplastic anemia (SAA), or may selectively involve single lineages, as in pure red cell aplasia (PRCA) or in agranulocytosis (AGR). All these conditions share a cellular immune-mediated pathophysiology, which is supported by many experimental data; thus, various immunosuppressive (IS) strategies have been exploited. Alemtuzumab (MabCampath®) (ALE) is a lympholytic MoAb with strong and prolonged IS activity, more reliable than ATG or ALG as for activity, dosing and commercial availability. Here we report a phase II/III pilot study with ALE followed by low-dose cyclosporine A (CsA) on 11 patients suffering from SAA (n=4), PRCA (n=5) or AGR (n=2). All patients received ALE as s.c. injection premedicated by betamethasone, clorpheniramine and paracetamol, with a dose escalating schedule of 3-10-30-30-(30) mg in consecutive days; the total dose was 103 mg for SAA, and 73 for PRCA and AGR. Six patients received one or more additional courses as a result of relapse, so a total of 18 courses were administered. All patients on day 7 started oral low dose CsA (1 mg/kg). Valgancyclovir 450 mg bi-daily and trimethoprim-sulphamethoxazole bi-daily thrice a week were administered as anti-CMV and anti-Pneumocystis Carinii prophylaxis, respectively. All patients completed the treatment, with severe or moderate infusion-related side effect (fever, chills and/or injection site reaction) occurring in 1 (not premedicated) and 3 cases, respectively. No significant abnormality of routine biochemical testing, nor other medically significant adverse events were reported. A complete lympho-ablation was observed in all patients within 2–3 days, which persisted for several weeks; in addition, transient worsening of neutropenia (managed by occasional G-CSF support) and of thrombocytopenia were observed in some patients. At a median follow-up of 6 months, infectious events were irrelevant: in cumulative 75 patient-months, 1 HSV and 1 flu have been recorded (globally 1 day of fever), all resolving quickly. No CMV reactivation was demonstrated. Immune reconstitution was delayed up to several months, with absolute lymphocyte count ranging between 30–200/uL, 100–400/uL, 250–800/uL and 500–2000/uL at months +1, +3, +6 and +12 from the treatment. The CD4+ compartment was significantly more affected than the CD8+, with a persistent inversion of the CD4/CD8 ratio. As for efficacy, the 4 SAA patients showed 1 CR, 1 PR (both relapsing at 6 months and re-treated with additional ALE courses), 1 NR at 3 months (addressed to early stem cell transplantation due to life-threatening hemorrhages); 1 is not evaluable yet. In the 5 PRCAs, there were 4 CR and 1 NR (at 3 months); 3 responding patients relapsed and were successfully managed by further courses of ALE. The 2 AGRs showed both CR, followed by late relapse (at 18 months) in one case (now receiving a second course). In conclusion, ALE administered as subcutaneous injection is a feasible and safe IS regimen for patients suffering from immune-mediated marrow failure syndromes. Infectious complications were unremarkable, and preliminary results suggest good efficacy, especially in lineage-restricted forms; as with other IS regimens, the hematological response is late (3–4 months) and relapses may occur, which are sensitive to further ALE courses. Such favorable risk-to-benefit ratio predicts for this regimen a leading position in the future IS strategies.