Table 3 Overview of interventions per drug.

From: Reasons for non-feasibility of therapeutic drug monitoring of oral targeted therapies in oncology – an analysis of the closed cohorts of a multicentre prospective study

 

All patients

Main reason for closing the cohort

 

≥ 1 low Cmin

All adequate PK levels

 

Intervention

No intervention

 

Treatment continued

Dose reduction due to toxicity

Treatment discontinued due to toxicity

Treatment interruption due to toxicity

 

Successful

Not successful

 

Toxicity

Physician adherence

Discon- tinued

Logistics

Borderline low PK levels

 

Still low PK levels

Toxicity

 

All drugs

270

127 (47)

47 (37)

30 (63.8)

17 (26.2)

9 (52.9)

8 (47.1)

80 (63)

46 (57.5)

15 (18.8)

8 (10)

6 (7.5)

5 (6.3)

143 (53)

103 (72)

16 (11.2)

12 (8.4)

12 (8.4)

Cabozantinib

25

20 (80)

5 (25)

2 (40)

3 (60)

1 (33.3)

2 (66.7)

15 (75)

14 (93.3)

0 (0)

0 (0)

1 (6.7)

0 (0)

5 (20)

4 (80)

0 (0)

1 (20)

0 (0)

Toxicity

Dabrafenib/ trametinib

65

18 (27.7)

6 (33.3)

4 (66.7)

2 (33.3)

1 (50)

1 (50)

12 (66.7)

3 (25)

3 (25)

3 (25)

1 (8.3)

2 (16.7)

47 (72.3)

33 (70.2)

2 (4.3)

0 (0)

12 (25.5)

Toxicity

Enzalutamide

42

2 (4.8)

1 (50)

1 (100)

0 (0)

0 (0)

0 (0)

1 (50)

0 (0)

0 (0)

1 (100)

0 (0)

0 (0)

40 (95.2)

32 (80)

6 (15)

2 (5)

0 (0)

PK levels above target

Erlotinib

3

0 (0)

0 (0)

0 (0)

0 (0)

0 (0)

0 (0)

0 (0)

0 (0)

0 (0)

0 (0)

0 (0)

0 (0)

3 (100)

3 (100)

0 (0)

0 (0)

0 (0)

PK levels above target

Everolimus

25

13 (52)

4 (30.8)

2 (50)

2 (50)

1 (50)

1 (50)

9 (69.2)

7 (77.8)

0 (0)

0 (0)

1 (11.1)

1 (11.1)

12 (48)

2 (16.7)

3 (25)

7 (58.3)

0 (0)

Toxicity

Olaparib

35

27 (77.1)

17 (63)

12 (70.6)

5 (29.4)

4 (80)

1 (20)

10 (37)

5 (50)

1 (10)

1 (10)

2 (20)

1 (10)

8 (22.9)

6 (75)

2 (25)

0 (0)

0 (0)

Other

Palbociclib

32

22 (68.7)

7 (31.8)

4 (57.1)

3 (42.9)

1 (33.3)

2 (66.7)

15 (68.2)

9 (60)

4 (26.7)

0 (0)

1 (6.7)

1 (6.7)

10 (31.3)

8 (80)

2 (20)

0 (0)

0 (0)

Other

Regorafenib

9

6 (66.7)

1 (16.7)

0 (0)

1 (100)

1 (100)

0 (0)

5 (83.3)

1 (20)

3 (60)

1 (20)

0 (0)

0 (0)

3 (33.3)

2 (66.7)

1 (33.3)

0 (0)

0 (0)

Toxicity

Tamoxifen

22

7 (31.8)

5 (71.4)

4 (80)

1 (20)

0 (0)

1 (100)

2 (28.6)

2 (100)

0 (0)

0 (0)

0 (0)

0 (0)

15 (68.2)

13 (86.7)

0 (0)

2 (13.3)

0 (0)

Other

Vismodegib

12

12 (100)

1 (8.3)

1 (100)

0 (0)

0 (0)

0 (0)

11 (91.7)

5 (45.5)

4 (36.4)

2 (18.2)

0 (0)

0 (0)

0 (0)

0 (0)

0 (0)

0 (0)

0 (0)

Toxicity

  1. Data are expressed as number (%). Due to rounding, total percentages could be deviating from 100%. Cmin: minimum plasma concentration; PK Pharmacokinetic.
  2. Patients had ≥ 1 low Cmin or all adequate PK levels. If patients had ≥ 1 low Cmin they did or did not have an intervention. If they had an intervention, it was described as successful when median Cmin after intervention was above target and there was no dose-limiting toxicity within one month, or otherwise as a not successful intervention. If not a successful intervention, it was stated why. If no intervention was performed, the reason why was also stated. If patients had all adequate PK levels, it was stated if patients continued with the standard dose or if toxicity led to dose reduction, treatment discontinuation or treatment interruption. Lastly, the main reason for closing the cohort was stated.
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