Subcutaneous Anti-D as Treatment of Idiopathic Thrombocytopenic Purpura in Children; Clinical Observations.
Authors: Kjaersgaard Mimi , Hasle Henrik 
Published: April 2020

Abstract
Treatment options for patients suffering from idiopathic thrombocytopenic purpura (ITP) mostly involve intravenous IgG (IVIG) or intravenous anti-D. Subcutaneous (s.c.) anti-D may be an attractive alternative; easy to administer and with less side effects. We present the clinical experience from treating six children suffering from ITP with s.c. anti-D.
Five of the six patients had chronic ITP. One patient (patient number 3) had acute ITP. All patients with chronic ITP had been treated with IVIG prior to s.c. anti-D treatment, but not within four weeks before. Platelet counts (PLT) increased after all IVIG treatments, but for patient number 1 and 2 the increase was limited with repeated courses. Patient number 4 had also been treated with steroid with no effect.
The number of anti-D treatments varied from 1–12. Only patient number 2 received 12 treatments. Doses were 50μg/kg or 75μg/kg anti-D. When treated, all patients had cutaneous bleeding. In patient number 1, episodes with epistaxis and gum bleeding also occurred.
After s.c. anti-D cutaneous bleeding manifestations were reduced in five patients. In patient number 3 symptoms remained unchanged after the second treatment. Patient number 4 had no detectable clinical effect of the s.c anti-D.
The effect on PLT varied greatly (table 1). Repeated increases in PLT to above 20•109/L were achieved in patient number 1. After the first treatment of patient number 2, PLT increased from 10•109/L to 37•109/L associated with a marked reduction in petechiae and bruising. In patient number 3 PLT increased only after the first treatment from 10•109/L to 67•109/L.
Time till relapse also varied. Relapse is here defined as; the first day after treatment where PLT was continuously below 10*109/L for two weeks or more. For patient number 1 time till relapse after treatment increased. In patient number 2 bleeding tendency was reduced with regular treatments. Therefore, he was treated every four weeks for six months, and received, in total, 12 treatments over a 32 months period. Patient number 5 was treated twice. After the last treatment PLT has remained stable. Soreness and minor bruising at injection site were reported side effects.
The average decrease in hemoglobin (Hgb) was 0.77 g/dL (range 0–2.4 g/dL). Lactate dehydrogenase (LDH) was not measured for all patients after every treatment, but the results available (table 1) indicated no or only minor degree of hemolysis. Patient number 3 reported dark morning urine 10 days after the second treatment. Dip-slide showed no hematuria. His Hgb was 11.0 g/dL and had decreased 0.5 g/ dL. LDH was not measured.
Subcutaneous anti-D treatment was clinical effective with few side effects in five of six patients. Four of the five patients had been treated with IVIG prior to s.c. anti-D. Subcutaneous anti-D may be an attractive therapy, and the effect is under further investigation in a multi center trial.
Demographic and paraclinical data Patient number Sex Age at onset of ITP (Years) S.C. Anti-D Duration of ITP at treatment (months) PLT (start/end) [•109/L] Relapse (day after treatment) LDH (before →after) [U/I] * After first treatment 1 M 3 19 2–4 / 58–334 56–125 (no control) 2 M 2 17 6–16 / (no control) (no control) 571→732 3 M 10 0 3- 10 / 7–67 78* 502→523 4 M 4 67 1 / 7 n/a 230→227 5 F 4 9 7–19/ 67–93 n/a 240→257 6 F 7 10 3 / 62 22 292→321