Table 2.
Summary of baseline characteristics.
| Baseline characteristicsa | Avapritinibb | BATb | pc |
|---|---|---|---|
| Number of unique patients | N = 176 | N = 141 | |
| Number of lines of therapy | N = 176 | N = 222 | |
| Demographic characteristics | |||
| Age (years)d | 0.817 | ||
| Mean (SD) | 66.3 (10.7) | 65.5 (11.8) | |
| Median (min, max) | 68.0 (31.0, 88.0) | 67.8 (20.9, 87.5) | |
| Sex, n (%) | |||
| Female | 73 (41.5%) | 76 (34.2%) | 0.168 |
| Male | 103 (58.5%) | 146 (65.8%) | 0.168 |
| Region, n (%) | |||
| North America | 102 (58.0%) | 34 (15.3%) | <0.001* |
| Europe | 74 (42.0%) | 188 (84.7%) | <0.001* |
| Medical history | |||
| ECOG Performance statuse | 0.093 | ||
| n (%) | 176 (100.0%) | 222 (100.0%) | |
| Mean (SD) | 1.2 (0.8) | 1.0 (0.7) | |
| Median (min, max) | 1.0 (0.0, 3.0) | 1.0 (0.0, 3.0) | |
| ECOG category, n (%) | |||
| 0 | 36 (20.5%) | 50 (22.5%) | 0.707 |
| 1 | 92 (52.3%) | 129 (58.1%) | 0.288 |
| ≥2 | 48 (27.3%) | 43 (19.4%) | 0.081 |
| Anemiaf, n (%) | 104 (59.1%) | 125 (56.3%) | 0.648 |
| Thrombocytopeniag, n (%) | 67 (38.1%) | 120 (54.1%) | <0.01* |
| Disease characteristics | |||
| AdvSM subtype diagnosis,h n (%) | |||
| SM-AHN | 119 (67.6%) | 121 (54.5%) | <0.05* |
| ASM | 29 (16.5%) | 68 (30.6%) | <0.01* |
| MCL | 28 (15.9%) | 33 (14.9%) | 0.883 |
| Any skin involvement, n (%) | 58 (33.0%) | 71 (32.0%) | 0.922 |
| Leukocyte count ≥16 × 109/l, n (%) | 33 (18.8%) | 54 (24.3%) | 0.225 |
| Serum tryptase level ≥125 ng/mli, n (%) | 132 (75.0%) | 144 (64.9%) | <0.05* |
| KIT mutationj | |||
| Patients tested, n (%) | 170 (96.6%) | 140 (99.3%) | 0.137 |
| Tested positive for KIT D816V, n (%) | 156 (91.8%) | 128 (91.4%) | 1.000 |
| SRSF2/ASXL1/RUNX1 gene panelj | |||
| Patients tested for at least one mutation, n (%) | 176 (100.0%) | 107 (75.9%) | <0.001* |
| Number of mutated genes within the SRSF2/ASXL1/RUNX1 gene panel, n (%) | |||
| 0 | 92 (52.3%) | 41 (38.3%) | 0.031 |
| 1 | 54 (30.7%) | 44 (41.1%) | 0.097 |
| ≥2 | 30 (17.0%) | 22 (20.6%) | 0.560 |
| Prior therapy | |||
| Patients with prior systemic therapy, n (%) | 110 (62.5%) | 104 (46.8%) | <0.01* |
| Number of prior systemic therapy lines received, n (%) | <0.001* | ||
| Mean (SD) | 1.0 (1.1) | 0.1 (0.3) | |
| Median (min, max) | 1.0 (0.0, 6.0) | 0.0 (0.0, 2.0) | |
| 0 | 66 (37.5%) | 118 (53.2%) | <0.01* |
| 1 | 68 (38.6%) | 69 (31.1%) | 0.142 |
| 2 | 28 (15.9%) | 24 (10.8%) | 0.177 |
| ≥3 | 14 (8.0%) | 11 (5.0%) | 0.309 |
| Prior treatments received, n (%) | |||
| TKI therapy | 92 (52.3%) | 50 (22.5%) | <0.001* |
| Cytoreductive therapy | 33 (18.8%) | 61 (27.5%) | 0.055 |
| Biologic or other systemic therapyk | 23 (13.1%) | 30 (13.5%) | 1.000 |
ASM aggressive systemic mastocytosis, BAT best available therapy, ECOG Eastern Cooperative Oncology Group, max maximum, min minimum, MCL mast cell leukemia, SD standard deviation, SM-AHN systemic mastocytosis with associated hematologic neoplasm, TKI tyrosine kinase inhibitor.
*p < 0.05.
aThe baseline period was defined as 8 weeks leading up to the index date for the avapritinib cohort and the 12 weeks leading up to the index date for the BAT cohort.
bThe trial and real-world samples were restricted to patients with available ECOG score during any time before to 3 months after the index date.
cFor categorical variables with expected counts <5, Fisher’s exact tests were used instead of chi-squared.
dOnly the year of birth was collected for the BAT cohort. Patients’ age was calculated using the mid-point of the birth year as approximate dates of birth.
eFor the BAT cohort, ECOG and Karnofsky scores assessed during 12 months before to 3 months after the index date were considered. For the lines of therapy for which patients had no ECOG score on record during this period (N = 9 lines of therapy), the Karnofsky score closest to the index date in the same period was converted to an ECOG score. The conversion was performed according to Oken et al. [37].
fFor both the avapritinib cohort and the BAT cohort, anemia included reported anemia and hemoglobin <10 g/dl.
gFor both the avapritinib cohort and the BAT cohort, thrombocytopenia included reported thrombocytopenia and platelet count less than 100 × 109/l.
hThe AdvSM subtype was assessed at the last diagnosis evaluation prior to or on the index date.
iObservations with missing serum tryptase were imputed as not having serum tryptase greater than or equal to 125 ng/ml.
jStatistics on KIT mutation and SRSF2/ASXL1/RUNX1 gene panel were reported at the patient level.
kOther systemic therapy included steroids and thalidomide or derivatives.