Hydroxyurea-Refractory and -Intolerant ET

The optimal second-line therapy is unclear and there is a lack of large-scale controlled clinical trials. The situation in New Zealand is further complicated by the lack of funding for treatments commonly recommended by overseas experts.

Anagrelide

The PT-1 trial⁴ found anagrelide plus aspirin to be inferior to hydroxyurea plus aspirin, although the platelet counts were similar in both groups. Patients who received anagrelide had higher rates of arterial thrombosis, major haemorrhage, and myelofibrotic transformation, but lower rates of venous thrombosis.

The ANAHYDRET study⁴ did not find anagrelide to be inferior to hydroxyurea, but the patients' numbers and follow-up were both less than in the PT-1 trial. The non-inferiority design in this study has also been questioned.

Anagrelide has been used in conjunction with hydroxyurea. Fibrosis has been seen with anagrelide, and was reversible in a small number of patients. Some experts recommend follow-up trephine biopsies every 2–3 years.

See Beer PA, Green AR (2009)⁴ for further reading about treatment and treatment rationale.

Pegylated interferon-2-alpha

This has shown similar efficacy in ET to PV, and may be considered preferable in patients <40 years – although it is not funded in New Zealand. See Hydroxyurea-Refractory and -Intolerant PV for additional information.

Pipobroman, phosphorus-31 and bulsulfan

These are other options that can be considered, especially in older patients who are refractory to hydroxyurea and anagrelide. See Hydroxyurea-Refractory and -Intolerant PV for additional information.


About this Canterbury DHB document (6217):
Document Owner:	Bridgett McDiarmid (see Who's Who)
Last Reviewed:	August 2018
Next Review:	April 2021
Keywords:
Note: Only the electronic version is controlled. Once printed, this is no longer a controlled document. Disclaimer The Haematology Department Protocols and Guidelines (the Red Book) are intended as a guide for registered health professionals to communicate guidelines and share best practices with supporting health professionals within New Zealand district health boards. They are not intended to be provided to or used as a reference for patients or non-registered health professionals. All health professionals must exercise their own clinical judgement and use pertinent clinical data when treating patients. The authors and editors of this publication have checked with sources believed to be reliable in their effort to provide information that is complete and in accord with the standards accepted at the time of publication. However, in view of the possibility of human error or changes in medical science, neither the authors, editors, publisher, nor any other party who has been involved in preparing or publishing this work warrants that the information contained in it is accurate or complete in every respect. They therefore have no liability (whether in tort (including negligence) or otherwise) for any loss or damage arising out of any reliance on this information. This publication has been compiled by the staff and contractors of Canterbury District Health Board (CDHB) and as such CDHB has copyright for this book. Amendments must be authorised in accordance with the documented process. No release of part of, or all of, this publication to any other party or organisation is permissible without the prior approval of the designated document owner.
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