Table 2 Initiation dose of palbociclib and patterns of dose reductions among patients treated with palbociclib + letrozole

Total patients (n (%)

612

(100)

336

(54.9)

445

(72.7)

524

(85.6)

Patients with known starting dose

417

(68.1)

269

(80.1)

323

(72.6)

367

(70.0)

Patients with unknown starting dose

195

(31.9)

67

(19.9)

122

(27.4)

157

(30.0)

Starting dose (n (% of patients with known starting dose))

 125 mg

367

(88.0)

237

(88.1)

283

(87.6)

321

(87.5)

 100 mg

46

(11.0)

30

(11.2)

38

(11.8)

42

(11.4)

 75 mg

4

(1.0)

2

(0.7)

2

(0.6)

4

(1.1)

Number of dose reductions (n (% of patients with known dose))

 None

333

(79.9)

185

(68.8)

240

(74.3)

309

(84.2)

  ≥ =1

84

(20.1)

84

(31.2)

83

(25.7)

58

(15.8)

Type of first dose reduction (n (% of patients with known dose))

 Reduction from 125 mg to 100 mg

65

(15.6)

65

(24.2)

64

(19.8)

45

(12.3)

 Reduction from 100 mg to 75 mg

6

(1.4)

6

(2.2)

6

(1.9)

5

(1.4)

 Reduction from 125 mg to 75 mg

13

(3.1)

13

(4.8)

13

(4.0)

8

(2.2)

Days to first dose reduction (mean, SD)

48

(31)

48

(31)

48

(31)

46

(31)