Interest of a Targeted Therapy for the Treatment of a Severe Form of Hypersensitivity to Drug (DRESS Syndrome)

Inclusion criteria

• Adult patients (minimum 18year-old)
• diagnosed at D0 (= baseline and inclusion) with DRESS defined by:

• with a REGIScar score at D0 calculated at at least 4 (4 or 5: probable DRESS; >5: definite case of DRESS), see Annex: REGIScar criteria
• Skin eruption with an onset considered as compatible with a DRESS syndrome according to the investigator's opinion after the uptake of one or several drug(s)
• AND Fever ≥ 38°C at the time of the examination or notion of a thermal peak ≥ 38°C in the preceding 72 hours.
• At least 1 organ disorder compatible with the diagnosis of DRESS syndrome among the following disorders:

• Adenopathies present in at least 2 different sites and ≥ 1 cm in size
• Acute hepatitis defined by :

• Elevation of liver enzymes in serum: ALAT (Alanine Aminotransferase) and/or ASAT (Aspartate Aminotransferase)
• AND/OR an increase in serum total bilirubin, according to the standards of the local analysis laboratory (in the absence of a history of liver disease: ASAT and/or ALAT ≥ 3N (=3 times normal)
• AND/OR total bilirubin ≥ 2N
• Acute renal failure defined by :

• An increase in creatinine according to local laboratory standards
• AND a sterile cytobacteriological examination (in the absence of a history of renal disease: creatininaemia ≥ 1.5N
• AND/OR increase in creatinine ≥ 0.3 mg/dl (or ≥ 26.5 mol/L)
• AND/OR urine output < 0.3 ml/kg/h (over ≥ 24h).
• Pulmonary impairment defined by:

• Oxygen saturation (SpO2) measured by pulse oximetry ≤ 95% in room air
• And/or the presence of an interstitial syndrome on a standard chest X-ray or a CT scan of the chest (in the absence of any other cause of lung damage).
• With eosinophilia (blood eosinophil count ≥ 500/mm3 or ≥0.5 G/L).
• Patient having given written informed consent
• patient with social insurance

Exclusion criteria

• Patients <18 year-old
• Patients with DRESS with REGIScar score <4
• Patients without skin eruption at baseline
• Eosinophils blood count <500/mm3 or < 0.5 G/L at baseline
• Patients with contra-indication to blood samples dedicated to the biocollection, according to the investigator's opinion
• Patients with contra-indication to stop the culprit drug(s) involved in DRESS
• Past history of hypersensitivity to biological drugs
• Patients who received a previous anti-IL5 or anti-IL5 receptor therapy within 5 half lives (= 4 months) before inclusion
• Patients with a contra-indication of topical corticosteroids (mainly a past history of contact eczema with clobetasol propionate)
• Pregnancy and lactation