Table 3.

Mechanisms of CD19 loss during blinatumomab treatment

Sample ID	CD19 LOH or CNA	CD19 mutations	Sum AF of CD19 mutations	CD19 RNA expression (log CPM)	Summary of CD19 loss
SJBALL042232_R2	Loss of chromosome 16	p.Y259fs (c.775 T>TGT)	0.79	Normal (5.3)	CD19 mutation
		p.Y259fs (c.776 A>ATTGGAGATCCC)			Loss of chromosome 16
SJALL061897_R1	Loss of chromosome 16	p.K258fs (c.773 AGTATTAT>AAAAAAA)	0.79	Normal (5.2)	CD19 mutation
					Loss of chromosome 16
SJALL061895_R1	Loss of chromosome 16	p.109fs (c.326 C>CA)	0.65	Normal (5.4)	CD19 mutation
		p.Q186sp			Loss of chromosome 16
		p.P278sp
SJALL061893_R1	No	p.P60del (c.179 CCTT>C)	0.73	Normal (6.1)	CD19 mutation
					Allele-specific expression
SJALL061894_R1	No	p.S269* (c.806 C>A)	0.15	Low (0.4)	CD19 mutation
					Allele-specific expression (low)
SJBALL042246_R2	No	None	0	Low (0.8)	Low level of CD19 expression
SJALL061896_R1	No	None	0	Normal (6.2)	CD19 wild type
					CD81 mutation

CNA, copy-number abnormality; CPM, count per million; LOH, loss of heterozygosity.