Cancer Chemotherapy and Pharmacology

, Volume 67, Issue 4, pp 967–969

Durable remission after treatment with very low doses of imatinib for FIP1L1-PDGFRα-positive chronic eosinophilic leukaemia

  • Grzegorz Helbig
  • Andrzej Moskwa
  • Marek Hus
  • Jarosław Piszcz
  • Alina Swiderska
  • Alina Urbanowicz
  • Małgorzata Całbecka
  • Ilona Seferyńska
  • Małgorzata Raźny
  • Marek Rodzaj
  • Ewa Żuk
  • Sławomira Kyrcz-Krzemień
Open AccessLetter to the Editor

DOI: 10.1007/s00280-011-1582-3

Cite this article as:
Helbig, G., Moskwa, A., Hus, M. et al. Cancer Chemother Pharmacol (2011) 67: 967. doi:10.1007/s00280-011-1582-3

To the Editor,

The exquisite response to imatinib mesylate in patients with chronic eosinophilic leukaemia (CEL) harbouring the FIP1L1-PDGFRα (F/P) fusion transcript has been well documented [14]. In the up-to-date largest multicentre study, all 27 patients with detectable F/P mutation achieved complete haematological and molecular remission after imatinib therapy and have remained in continuous remission after median of 25 months [2].

The initial daily doses of imatinib ranged from 100 to 400 mg in a majority of published reports, but maintained imatinib doses were not fully established [2, 5]. It was also demonstrated that imatinib dose reduction or temporary discontinuation was associated with molecular and clinical relapse [6, 7]. Additionally, single cases of imatinib-resistant F/P-positive CEL have been reported [8].

As the response rate after imatinib is close to 100%, the current issue is (1) to establish a minimal effective imatinib dose needed to remission maintenance and (2) to evaluate the duration of imatinib response.

Recently, we reported on high efficacy of weekly imatinib schedule in 13 F/P-positive CEL patients. Imatinib at weekly dosage seemed to be sufficient to maintain haematological and molecular remission with a median of 21 months of follow-up in this studied subgroup [9].

Herein, we present long-term results of F/P-positive CEL after imatinib. The data were collected from ten centres in Poland. All patients gave written informed consent. Twenty male and two female patients at median age of 52 years (range 22–80 years) were included in this partially retrospective study. Organ involvement was demonstrated in 91% of patients, and splenomegaly was the most common clinical manifestation. At diagnosis, 23% of patients were asymptomatic. Median blood eosinophilia and median bone marrow eosinophil infiltration were 12 × 109/l (range 2.5–40) and 39.5% (range 7.0–80), respectively. The starting, de-escalated and maintained imatinib doses were left to the physician’s discretion. The initial imatinib doses were as follows: 100 mg/day (n = 18), 400 mg/day (n = 3) and 300 mg/day (n = 1). All treated patients achieved haematological remission after median of 13 days (range 3–90). Complete molecular remission by nested RT-PCR was confirmed after median of 10 months (range 3–24). They became free of symptoms. The maintained imatinib doses were following: 100 mg per week (n = 11), 200 mg per week (n = 2), 400 mg per week (n = 1), 100 mg twice a week (n = 2), 100 mg thrice a week (n = 2) and 100 mg a day (n = 4). Imatinib doses and duration of treatment were shown in Table 1. All studied patients remained in complete haematological and molecular remission after median follow-up of 41 months (range 11–71). Median time at maintained imatinib doses was 27 months (range 2–61). Imatinib plasma levels were measured using high-performance liquid chromatography-tandem mass spectrometry method [10]. Blood samples were taken 24 h after the last imatinib intake from eleven patients: from 9 patients on 100 mg weekly imatinib and from 2 on imatinib at 200 mg a week. Imatinib plasma levels appeared to be extremely low and ranged between 44 and 164 ng/ml and 103–203 ng/ml, respectively, for both analysed groups. Of note is that F/P negativity was confirmed at the same time points by nested RT-PCR.
Table 1

Imatinib doses and duration of therapy in F/P-positive CEL patients

Patients

Starting imatinib dose (mg/day)

First de-escalated imatinib dose (mg)

Maintained imatinib dose (mg)

Plasma imatinib level at maintained imatinib dose (ng/ml)

Months on maintained imatinib dose

Total time on imatinib (months)

Patient 1

100

200 per week

100 per week

46

54

67

Patient 2

100

200 per week

100 per week

47

61

66

Patient 3

400

400 per week

100 per week

44

3

12

Patient 4

100

100 BIW

100 per week

125

18

54

Patient 5

100

100 per week

100 per week

24

34

37

Patient 6

100

100 per week

100 per week

67

31

40

Patient 7

100

100 per week

100 per week

99

29

30

Patient 8

100

100 per week

100 per week

164

56

58

Patient 9

100

100 BIW

100 per week

123

8

17

Patient 10

100

100 per week

100 per week

ND

15

51

Patient 11

100

100 per week

100 per week

ND

16

19

Patient 12

400

100 daily

200 per week

ND

41

63

Patient 13

400

100 daily

200 per week

ND

43

45

Patient 14

100

100 BIW

100 BIW

103

27

28

Patient 15

100

100 BIW

100 BIW

203

4

14

Patient 16

100

100 TIW

100 TIW

ND

16

64

Patient 17

100

100 TIW

100 TIW

ND

11

71

Patient 18

100

100 BIW

400 per week

ND

2

39

Patient 19

100

NA

100 daily

ND

NA

50

Patient 20

100

NA

100 daily

ND

NA

37

Patient 21

100

NA

100 daily

ND

NA

11

Patient 22

300

100 daily

100 daily

ND

40

41

BIW twice a week, TIW thrice a week, ND not done, NA not applicable

With this large series of F/P-positive CEL patients, we can confirm that imatinib may induce durable remission with the maximum follow-up of 71 months until last contact. Most recently, Rondoni et al. [11] presented the follow-up results of 33 F/P-positive CEL patients on imatinib with a continuous remission after median of 51 months (range 30–92). In contrary to our report, the maintained imatinib doses were 100 mg a day. It is noteworthy that 18 patients from our study group received imatinib at total maintained doses of 400 mg a week or less. We have proved that treatment with such low imatinib doses may maintain molecular remission despite low imatinib plasma levels. Nevertheless, the longer follow-up is needed to confirm our encouraging results.

Open Access

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Copyright information

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Authors and Affiliations

  • Grzegorz Helbig
    • 1
  • Andrzej Moskwa
    • 2
  • Marek Hus
    • 3
  • Jarosław Piszcz
    • 4
  • Alina Swiderska
    • 5
  • Alina Urbanowicz
    • 6
  • Małgorzata Całbecka
    • 7
  • Ilona Seferyńska
    • 8
  • Małgorzata Raźny
    • 9
  • Marek Rodzaj
    • 9
  • Ewa Żuk
    • 10
  • Sławomira Kyrcz-Krzemień
    • 1
  1. 1.Departament of Haematology and Bone Marrow TransplantationSilesian Medical UniversityKatowicePoland
  2. 2.Department of HaematologyProvincial HospitalGorzowPoland
  3. 3.Department of HaematologyMedical UniversityLublinPoland
  4. 4.Department of HaematologyMedical UniversityBiałystokPoland
  5. 5.Department of HaematologyProvincial HospitalZielona GóraPoland
  6. 6.Department of HaematologyProvincial HospitalSuwałkiPoland
  7. 7.Department of HaematologyProvincial HospitalToruńPoland
  8. 8.Institute of Haematology and Transfusion MedicineMedical UniversityWarsawPoland
  9. 9.Department of Haematology and Internal MedicineRydygier HospitalKrakówPoland
  10. 10.Department of HaematologyProvincial HospitalSzczecinPoland