Table 3 Response data in single-cell-derived myeloid progenitor cells (CFU-GM colonies) on midostaurin and avapritinib in 13 KIT D816V positive advanced systemic mastocytosis patients stratified in midostaurin + avapritinib responder (cohort #1), midostaurin non-responder + avapritinib-responder (cohort #2), midostaurin + avapritinib non-responder (cohort #3), and midostaurin responder^f (cohort 4) according to relative reduction of KIT D816V positive colonies

#	Midostaurin in vivo (months)	Response^a (Valent et al.) [3]	KIT D816V EAB change in PB on midostaurin^b (%) (Jawhar et al.) [20]	OS from diagnosis (months)	Death (yes/no)	KIT D816V positive colonies (%) (prior to treatment)	KIT D816V positive colonies (%) (on midostaurin in vivo)^c	KIT D816V positive colonies (%) (on midostaurin in vitro)^d	KIT D816V positive colonies (%) (on avapritinib in vitro)^e
Cohort #1
3	6	Yes (MPR)	82 (↓)	42	No	100	40	50	0
7	23	Yes (IR)	43 (↓)	33	No	70	10	−	0
11	13	Yes (IR)	72 (↑)	133	No	80	80	40	10
13	20	Yes (IR)	76 (↓)	283	No	30	10	10	0
Cohort #2
1	3	No (PD)	0	23	Yes	40	−	60	0
2	3	No (PD)	−	22	Yes	100	−	100	0
5	7	No (PD)	23 (↑)	21	Yes	90	90	90	10
Cohort #3
4	7	No (PD)	3 (↑)	13	Yes	90	90	90	70
6	6	No (PD)	0	15	Yes	100	100	100	80
8	7	No (PD)	113 (↑)	34	Yes	100	100	100	100
12	11	No (PD)	24 (↓)	20	Yes	95	95	90	100
Cohort #4
9	31	Yes (MPR)	73 (↓)	54	Yes	90	5	−	−
10	22	Yes (IR)	62 (↓)	46	Yes	100	10	−	−

CFU-GM granulocyte-macrophage colony-forming-unit, EAB expressed allele burden, IR incomplete remission, MPR minor partial response, OS overall survival, PB peripheral blood, PD progressive disease
#Patient number
^aResponse according to modified Valent response criteria
^bKIT D816V EAB change from baseline to month six
^cKIT D816V positive colonies from patients on midostaurin at month six
^dKIT D816V positive colonies incubated with midostaurin (600 nM) for two weeks
^eKIT D816V positive colonies incubated with avapritinib (75 nM) for two weeks
^fData on avapritinib was not available

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