How we use cytoreductive drugs in patients with ET who need a cytoreductive treatment according to the risk stratification reported in Table 4
| Patient’s age* . | First-line treatment† . | Second-line treatment . |
|---|---|---|
| <40 y: Only 15% of patients under the age of 40 y need a cytoreductive treatment, either because of previous thrombosis or a PLT count ≥1500 × 109/L | Interferon α: Interferon α targets the mutant clone and therefore is a potential disease-modifying drug; in addition, it has no gonadal toxicity and no teratogenic or mutagenic effect | Hydroxyurea (or anagrelide‡) |
| 40-60 y: Only 20% of patients between the age of 40 and 60 y need a cytoreductive treatment, either because of previous thrombosis or a PLT count ≥1500 × 109/L | Interferon α or hydroxyurea: The choice depends on the patient’s occupation, lifestyle, desires, and expectations | Hydroxyurea or interferon α (or anagrelide‡) |
| >60 y: All patients need a cytoreductive treatment because of age | Hydroxyurea: Hydroxyurea involves fewer side-effects than interferon α and findings of observational studies suggest that this drug does not increase the risk of leukemic transformation. In our experience, significant side effects are found in <5% of patients and resistance to treatment is relatively uncommon | Busulfan (or interferon α§) |
| Patient’s age* . | First-line treatment† . | Second-line treatment . |
|---|---|---|
| <40 y: Only 15% of patients under the age of 40 y need a cytoreductive treatment, either because of previous thrombosis or a PLT count ≥1500 × 109/L | Interferon α: Interferon α targets the mutant clone and therefore is a potential disease-modifying drug; in addition, it has no gonadal toxicity and no teratogenic or mutagenic effect | Hydroxyurea (or anagrelide‡) |
| 40-60 y: Only 20% of patients between the age of 40 and 60 y need a cytoreductive treatment, either because of previous thrombosis or a PLT count ≥1500 × 109/L | Interferon α or hydroxyurea: The choice depends on the patient’s occupation, lifestyle, desires, and expectations | Hydroxyurea or interferon α (or anagrelide‡) |
| >60 y: All patients need a cytoreductive treatment because of age | Hydroxyurea: Hydroxyurea involves fewer side-effects than interferon α and findings of observational studies suggest that this drug does not increase the risk of leukemic transformation. In our experience, significant side effects are found in <5% of patients and resistance to treatment is relatively uncommon | Busulfan (or interferon α§) |
We use regular interferon α for treatment of ET following the indications and reimbursement criteria of the Italian Medicines Agency (AIFA): it should be noted, however, that pegylated forms of interferon α with better tolerance are used in many countries worldwide. Considering age distribution and proportions of patients who need a cytoreductive treatment at different age intervals (left column), with our approach the vast majority of patients are given hydroxyurea, and <1 in 10 are given interferon α.
Proportion of patients needing treatment based on the experience of the Department of Hematology Oncology, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy.
Rationale for the use of the specific cytoreductive drug.
We consider anagrelide as a second-line treatment in patients who refuse our proposal (hydroxyurea or interferon α).
We consider interferon α as a second-line treatment in patients over the age of 60 y who refuse treatment with busulfan.