Table 1.

Criteria to define positive expression of the proteins of interest based on previous reports.

For the cancer testis antigens: NY-ESO-1 and MAGE-A4 high and low positive expression was defined based on the current literature. In the Spearhead-I trial the cut-off for patient screening/enrollment was initially defined as a staining intensity of ≥1+ in ≥ 10 % of cells, but was later changed to ≥2+ or 3+ in ≥ 30 % of cells [34]. For BRD9 no cut-off was previously defined in literature.

Target protein	(High) positive expression	(Low) positive expression
MAGE-A4	≥ 30 % of cells with ≥ 2+ staining intensity in at least 2 cores [13,14]	≥ 10 % of cells with 1+ staining intensity, but < 2+ or 3+ in ≥ 30 % of cells [34]
NY-ESO-1	≥ 50 % of cells with ≥ 2+ staining intensity in at least 2 cores [18]	≥ 1 % of cells with 1+ staining intensity, but < 2+ or 3+ in ≥ 50 % of cells [35]
YAP1	Nuclear staining in ≥ 30 % of cells with a staining intensity of ≥ 2+ in at least 2 cores [27]
TAZ
CXCR4	≥ 1+ staining intensity in ≥ 1 % of cells in at least 2 cores [28]
BRD9	No cut-off defined in literature
SSX	> 5 % of cells with a staining intensity of ≥ 2+ in at least 2 cores [36]
SS18-SSX

Abbreviations: MAGE-A4: melanoma-associated antigen A4, NY-ESO-1: New York esophageal squamous cell carcinoma 1, YAP1: Yes associated protein 1, TAZ: transcriptional co-activator with PDZ-binding motif, CXCR4: chemokine receptor 4, BRD9: bromodomain-containing protein 9.