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\title{Successful treatment with cyclosporine and etanercept for deficiency of
adenosine deaminase 2}



\author[1]{Dai Keino}%
\author[1]{Kensuke  Kondoh}%
\author[1]{Yuhwa Kim}%
\author[1]{Akina Sudo}%
\author[1]{Ryo Ohyama}%
\author[1]{Mizuho Morimoto}%
\author[2]{Hiroshi Nihira}%
\author[2]{Kazushi Izawa}%
\author[3]{Sachiko  Iwaki-Egawa}%
\author[1]{Tetsuya Mori}%
\author[1]{Akitoshi Kinoshita}%
\affil[1]{St.marianna University School of Medicine Hospital}%
\affil[2]{Kyoto University}%
\affil[3]{Hokkaido Pharmaceutical University School of Pharmacy}%


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  \date{May 05, 2024}


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\par\null

ETHICS APPROVAL AND CONSENT TO PARTICIPATE

The study design was approved by the appropriate ethics review board.
Informed consent was obtained from the patient and parents to
participate.

CONSENT FOR PUBLICATION

Consent for publication was obtained from the patient and parents.

CONFLICT OF INTEREST

The authors have no conflicts of interest relevant to this article to
disclose.

AUTHOR CONTRIBUTIONS

\textbf{Dai Keino} : Conceptualization (lead); Writing -- original draft
(lead); Writing -- review and editing (equal).~\textbf{Kensuke Kondoh} :
Writing -- review and editing (equal).~\textbf{Yuhwa Kim} : Writing --
review and editing (equal). \textbf{Akina Sudo} : Writing -- review and
editing (equal). \textbf{Ryo Ohyama} : Writing -- review and editing
(equal). \textbf{Mizuho Morimoto} : Writing -- review and editing
(equal). \textbf{Hiroshi Nihira} : Investigation (equal).
\textbf{Kazushi Izawa} : Investigation (equal). \textbf{Sachiko
Iwaki-Egawa} : Investigation (equal). \textbf{Tetsuya Mori} : Writing --
original draft (supporting); Writing -- review and editing (equal).
\textbf{Akitoshi Kinoshita} : Conceptualization (supporting); Writing --
review and editing (equal).

Keywords: Adenosine deaminase 2 deficiency, cyclosporine, anti-tumor
necrosis factor, etanercept, pure red cell aplasia

To the Editor

Deficiency of adenosine deaminase 2 (DADA2) is an autoinflammatory
disease caused by loss-of-function homozygous or compound heterozygous
mutations in \emph{CECR1} (cat eye syndrome chromosome region
1).\textsuperscript{1,2} The phenotype of the DADA2 is widely
heterogeneous with a variable age of onset. Manifestations include
fever, early-onset lacunar stroke, livedo, portal hypertension, nodular
vasculitis, immunodeficiency, hepatospenomegaly, pure red cell aplasia
(PRCA), lymphopenia, cytopenia, and hypogammaglobulinemia. Treatment
mainly consists of anti-tumor necrosis factor (TNF) agents. Steroids are
also widely used for treatment and have shown variable success but often
with flares of inflammation and vasculitis upon tapering. Cyclosporine
(CyA), tacrolimus, cyclophosphamide, azathioprine, and methotrexate have
all been used with little success.\textsuperscript{1,2} Although
anti-TNF agents prevent strokes and improve the manifestations of
vasculitis in DADA2, their efficacy for treating PRCA and bone marrow
failure is less clear.\textsuperscript{3} Hematopoietic stem cell
transplantation may be considered for patients with severe hematologic
presentations.\textsuperscript{4}

Here, we present here a young female patient who was initially diagnosed
with idiopathic PRCA and later identified to have had compound a
heterozygous mutation in \emph{ADA2} associated with DADA2.
Administration of CyA and an anti-TNF agent (etanercept) successfully
induced and maintained remission.

A 13-year-old girl was admitted to our hospital with fatigability and
pallor. She has past histories of rash on her extremities at 8 months
old and erythema multiforme at 11 years old. Her physical examination
revealed palpebral conjunctival pallor and livedo reticularis of the
lower limbs. Laboratory examinations indicated anemia (white blood cell
count, 2900/\selectlanguage{greek}μ\selectlanguage{english}L; neutrophils, 70.0\%; lymphocyte, 21.5\%; blasts, 0.0\%;
hemoglobin (Hb), 4.6 g/dL; mean corpuscular volume, 81 fL; HbF, 0.4\%;
Reticuro, 1.9 \selectlanguage{ngerman}× 10\textsuperscript{4}/\selectlanguage{greek}μ\selectlanguage{english}L; and platelet count, 25.8 \selectlanguage{ngerman}×
10\textsuperscript{4}/\selectlanguage{greek}μ\selectlanguage{english}L). Transaminase and lactate dehydrogenase were
within normal ranges. IgA, IgM, and IgG were 42, 46, and 848 mg/dL,
respectively. Erythropoietin was 4,650 mIU/mL. Parvovirus, Epstein-Barr
virus, and cytomegalovirus were serologically negative.

Bone marrow aspirate and biopsy indicated marked erythroid hypoplasia,
and her nucleated cell count was 10.8 \selectlanguage{ngerman}× 10\textsuperscript{4}/\selectlanguage{greek}μ\selectlanguage{english}L.
Chromosomal banding of bone marrow cells was 46,XX{[}14/14{]}. Bone
marrow examination indicated no T cell receptor rearrangement. Computed
tomography of the chest revealed no thymoma. Mutations affecting genes
encoding ribosomal proteins causing Diamond Blackfan anemia were not
detected.

She was diagnosed with idiopathic pure red cell aplasia (PRCA).
Cyclosporine A (CyA) 4.5 mg/kg/day was started at approximately 1.5
months after admission because she was dependent on red blood cell
transfusion. Biopsy of the skin of the lower limb revealed necrotizing
vasculitis, and a diagnosis of cutaneous polyarteritis nodosa (cPAN) was
made (Fig 1). She responded to treatment with CyA and became
transfusion-independent. The dose of CyA was gradually reduced, and
approximately 10 months after diagnosis, she self-interrupted treatment
with CyA. Six months after self-interruption, she became
transfusion-dependent again. Resumption of CyA improved her anemia.

At the age of 17 years, no ADA2 enzyme activity was detected in the
patient's plasma (0.0 nmole/min/mL, normal range 2.38 \selectlanguage{ngerman}± 0.95
nmole/min/mL). The results of \emph{CECR1} sequencing revealed compound
heterozygous mutations: c.744delG p.Arg248fs and c.278T\textgreater{}C
p.lle93Thr. Thus, the patient was diagnosed with DADA2. Both parents and
her sister were not carriers. Magnetic resonance imaging of the head
showed no abnormal findings.

She continued to administer CyA but cPAN did not improve. She started
administration of an anti-TNF agent (etanercept) in combination with CyA
and noted improvement in her symptom sof cPAN such as livedo, edema, and
fatigue in the lower limbs. More than a year has passed since starting
etanercept with no adverse effects. Because Hb has remained at 11--12
g/dL, the amount of CyA has been tapered and is currently 0.5 mg/kg/day.

PRCA is a rare hematological disease characterized by bone marrow
erythroid aplasia. PRCA may be congenital or acquired; the acquired form
of chronic PRCA may present as a primary hematological disease in the
absence of any other diseases or secondary to thymoma,
lymphoproliferative disorders, infections, and collagen vascular
diseases or after exposure to various drugs or chemicals. PRCA
associated with DADA2 was described initially in three patients by
Hashem et al. and Ben-Ami et al. and further confirmed in additional
reports.\textsuperscript{5,6} A very early age of onset has been
reported for PRCA (median, 0.3 years; range, 0.1--12
years).\textsuperscript{7}

Initial treatment for PRCA includes the cessation of potentially
deleterious drugs and careful observation for one month while making
efforts to identify the cause of PRCA. Sawada et al. reported that CyA
and corticosteroids induced remission in 74\% and 60\% of patients,
respectively, and that discontinuance of maintenance therapy was
strongly correlated with relapse.\textsuperscript{8} Although PRCA and
other types of hematologic dysfunction associated with DADA2 generally
do not respond well to immunosuppressive agents such as azathioprine and
CyA,\textsuperscript{9} our patient achieved a response to CyA. CyA may
be useful for treating PRCA associated with DADA2.

PAN is considered a disease of adulthood with a median age of disease
onset of approximately the 4th to 5th decade of life. The annual
incidence of childhood vasculitis is estimated to be 20 per 100,000
individuals under 17 years of age.\textsuperscript{10} Many children
with PAN were found to have biallelic mutations in\emph{ADA2}
.\textsuperscript{1,2,9} The mainstay of treatment for
vasculitis/vasculopathy consists of anti-TNF agents (etanercept,
infliximab, adalimumab). Although CyA was ineffective for cPAN in our
patient, anti-TNF agents (etanercept) was effective, and at the age of
20 years, our patient has no neurological complications such as ischemic
strokes, intracranial hemorrhage, and a wide range of neuropathies.

REFERENCES

1. Zhou Q, Yang D, Ombrello AK, et al. Early-onset stroke and
vasculopathy associated with mutations in ADA2. \emph{N Engl J Med} .
2014;370:911-20.

2. Navon Elkan P, Pierce SB, Segel R, et al. Mutant adenosine deaminase
2 in a polyarteritis nodosa vasculopathy. \emph{N Engl J Med} .
2014;370:921-31.

3. Ombrello AK, Qin J, Hoffmann PM, et al. Treatment strategies for
deficiency of adenosine deaminase 2. \emph{N Engl J Med} .
2019;380:1582-4.

4. Hashem H, Kumar AR, Muller I, et al. Hematopoietic stem cell
transplantation rescues the hematological, immunological, and vascular
phenotype in DADA2. \emph{Blood} . 2017;130:2682-8.

5. Ben-Ami T, Revel-Vilk S, Brooks R, et al. Extending the clinical
phenotype of adenosine deaminase 2 deficiency. \emph{J Pediatr} .
2016;177:316-20.

6. Hashem H, Egler R, Dalal J. Refractory pure red cell aplasia
manifesting as deficiency of adenosine deaminase 2. \emph{J Pediatr
Hematol Oncol} . 2017;39:e293-6.

7. Lee PY, Kellner ES, Huang Y, et al. Genotype and functional
correlates of disease phenotype in deficiency of adenosine deaminase 2
(DADA2). \emph{J Allergy Clin Immunol} 2020; doi:
10.1016/j.jaci.2019.12.908.

8. Sawada K, Hirokawa M, Fujishima N, et al. PRCA Collaborative Study
Group: Long-term relapse-free survival and overall survival of patients
with acquired primary idiopathic PRCA receiving cyclosporine A: A
nationwide cohort study in Japan for the PRCA Collaborative Study
Group.\emph{Haematologica} . 2007;92:1021-8.

9. Hashem H, Kelly SJ, Ganson NJ, et al. Deficiency of Adenosine
Desminase 2 (DADA2), an Inherited Cause of Polyarteritis Nodosa and a
Mimic of Other Systemic Rheumatologic Disorders. \emph{Curr Rheumatol
Rep} . 2017;19:70.

10. Gardner-Medwin JM, Dolezalova P, Cummins C, et al. Incidence of
Henoch-Schonlein purpura, Kawasaki disease, and rare vasculitides in
children of di\selectlanguage{english}fferent ethnic origins. \emph{Lancet} . 2002;360:1197-202.

Figure legend

FIGURE 1. Skin of lower limb biopsy

Livedo reticularis was observed in both lower limbs to the acrotarsiums.

B, C. Necrotizing vasculitis (fibrinoid necrosis) accompanied by
neutrophil infiltration was found in the subcutaneous fatty tissue.\selectlanguage{english}
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