1987;8:138-40). • Only WT1 tumors with moderate to strong immunoreactive scores (4 -12) will be considered positive. The German IRS Scale for WT1 assessment by IHC is shown below: Percentage of positive cells X Intensity of Staining = IRS (0 – 12) (multiplication product) 0 = no positive cells 0 = no color reaction 0 – 1 = negative 1 = < 10% of positive cells 1 = mild reaction 2 – 3 = mild 2 = 10 -50% positive cells 2 = moderate reaction 4 – 8 = moderate 3 = 51 -80% positive cells 3 = intense reaction 9 – 12 = strongly positive 4 = > 80% positive cells IRS – points IRS – classification SELLAS Life Sciences Group Galinpepimut -S Protocol : SLS17 -201/ MK3475 -770 Protocol v1.1 (Amendment 1.0) 12 April 2019 Page 260 0 – 1 0 = negative 2 – 3 1 = positive, weak expression 4 – 8 2 = positive, moderate expression 9 – 12 3 = positive, strong expression The data on patient’s tumor/leukemic BM deposits WT1 expression levels will be collected using the Table below: Patient Initials Patient Study ID WT1 Immunoreactive Score (IRS) Date of Score Confirmation Source of Tested Slides: Institution Date of Accession Accession Number Section/Specimen Type _______________________________ ____________________________ Pathologist’s Name and Signature Date SELLAS Life Sciences Group Galinpepimut -S Protocol : SLS17 -201/ MK3475 -770 Protocol v1.1 (Amendment 1.0) 12 April 2019 Page 261 12.4. Appendix 4.