Table 1.

Pre-FLT3i–based therapy clinical characteristics and treatment outcomes in patients with secondary resistance (N = 67)

CharacteristicsTotal N = 67 N (%) [range]First-line n = 28 N (%) [range]Relapse/refractory n = 39 N (%) [range]
Median age, years62 [19–85]64 [27–83]62 [19–85]
Male gender32 (48)12 (43)20 (51)
Type of AML
De novo52 (78)22 (79)30 (77)
 Post-MDS, MPN, MDS/MPN12 (18)4 (14)8 (20)
 Therapy related3 (4)2 (7)1 (3)
WBC, ×109/L9 [0.1–208]37.45 [0.50–208]4.70 [0.1–123.3]
Hemoglobin, g/dl9.2 [6.0–15.5]8.85 [6.90–11.1]9.40 [6.0–15.5]
Platelets, ×109/L47 [3–316]41.50 [11–316]52.0 [7–223]
Bone marrow blasts, %60 [1–95]65.50 [10.0–95.0a]64.0 [12.0–92.0]
Cytogenetics
 Diploid karyotype43 (64)21 (75)22 (56)
 Adverse14 (21)4 (14)10 (26)
 Others10 (15)3 (11)7 (18)
Number of mutations at baseline4 [1–9]4 [1–8]4 [1–9]
Number of prior therapiesN/A2 [1–5]
Prior therapies
 Low-intensity chemotherapy/HMAN/A10 (24)
 Intensive chemotherapyN/A31 (76)
 ASCTN/A7 (18)
 FLT3iN/A18 (46)
Treatment
 Single-agent FLT3i2 (3)02 (5)
 FLT3i + LIT43 (64)14 (50)29 (74)
 FLT3i + CCT22 (33)14 (50)8 (21)
Type of FLT3i
 Type II46 (69%)21 (75)25 (64)
  Sorafenib39 (58)19 (68)20 (51)
  Quizartinib7 (11)2 (7)5 (13)
 Type I21 (31%)7 (25)14 (36)
  Midostaurin7 (10)4 (14)3 (8)
  Gilteritinib12 (18)3 (11)9 (23)
  Crenolanib2 (3)02 (5)
Treatment outcome
 CR24 (36)15 (54)9 (23)
 CRp17 (25)8 (28)9 (23)
 CRi26 (39)5 (18)21 (54)
Median duration of CRc, months4.7 [3.6–6.1]8.1 [5.6–9.6]3.6 [2.3–4.3]
Median OS, months14.1 [10.5–16.3]16.9 [14.7–25.6]8.4 [7.8–12.7]
ASCT in remission21 (31)12 (43)9 (23)
  • Abbreviations: ASCT, allogeneic stem cell transplant; HMA, hypomethylating agents; MDS, myelodysplastic syndrome; MPN, myeloproliferative neoplasm; N/A, not applicable; WBC, white blood count.

  • aOne patient was newly diagnosed with FLT3-mutated AML in another hospital with initial WBC >200 × 109/L, refused chemotherapy initially, and came to us after >1 month on hydroxyurea. The patient's initial BM at our institution shows 10% blast, but outside hospital peripheral blood analysis confirmed AML with >20% circulating blasts, and the patient was treated on an AML first-line clinical trial.