A trial of pacritinib for myelofibrosis (PERSIST- 1)

Cancer type:

Blood cancers




Phase 3

This trial compared pacritinib with other available treatments for myelofibrosis.

Myelofibrosis (pronounced my-eh-lo-fy-bro-sis) is a rare blood disorder. A small number of people with myelofibrosis go on to develop acute myeloid leukaemia.

More about this trial

Myelofibrosis can develop without having had any other condition. This is called primary myelofibrosis (PMF). It can also develop in people who have polycythaemia vera or thrombocythaemia. This is called secondary myelofibrosis. This trial was for people with either primary or secondary myelofibrosis.

Doctors treat myelofibrosis with chemotherapy, targeted cancer drugs and other drugs.

Pacritinib is a type of targeted cancer drug called a cancer growth blocker. It stops signals that cancer cells use to divide and grow.

The aim of this study was to see if pacritinib helped people with myelofibrosis more than other available treatments.

Summary of results

The trial team found that pacritinib was safe and could be a treatment for people with myelofibrosis.

327 people took part in this international phase 3 trial.

It was a randomised trial. Everyone was put in to 1 of 2 treatment groups. Neither you or your doctor could choose which group you were in.

2 out of every 3 people were put into the pacritinib group.

  • 220 people had pacritinib
  • 107 people had best available therapy (BAT)

Length of time treatment was taken

The average length of time people took pacritinib was just over 15½ (15.9) months.

The average length of time people took BAT was just under 6 (5.9) months.

After an average time of just over 6 (6.3) months, 90 people who were taking BAT stopped treatment and started to take pacritinib. The average length of time they continued taking pacritinib was just over 13½ (13.8) months.

An enlarged spleen is a symptom of myelofibrosis. The team wanted to know after 24 weeks of treatment how many people’s spleen had reduced by more than a third (35%). 

They found that the spleen had reduced in:

  • 42 people who had pacritinib
  • 5 people who had BAT

The team also looked at the 6 most common symptoms. These are:

  • fatigue and tiredness
  • feeling full early during a meal
  • tummy (abdominal) discomfort
  • night sweats
  • itching
  • bone pain

They also wanted to know how many people had a reduction in these symptoms by at least half (50%) after 24 weeks of treatment.

The symptoms had reduced by half for:

  • 54 people (25%) in the pacritinib group
  • 7 people (7%) in the BAT group

Symptoms improved quickly for those having pacritinib. After 4 weeks of treatment a fifth (20%) of the people in this group had their symptoms reduced by at least half.

At 48 weeks of treatment the team found that the number of people whose symptoms had reduced by at least half had increased by:

  • 42 people in the pacritinib group
  • 1 person in the BAT group

Side effects
The most common side effects of pacritinib included:

  • diarrhoea
  • feeling sick
  • a low amount of red blood cells
  • a low amount of platelets
  • being sick
  • tiredness
  • tummy (abdominal) pain

The most common side effects of BAT included:

  • diarrhoea
  • a low amount of red blood cells
  • a low amount of platelets
  • swelling of the hands and feet
  • a high temperature

The trial team concluded that pacritinib was safe and could be used as treatment for myelofibrosis. Because it reduced the symptoms, in particular an enlarged spleen, and kept their symptoms under control.

We have based this summary on information from the research team. The information they sent us has been reviewed by independent specialists (peer reviewed Open a glossary item) and published in a medical journal. The figures we quote above were provided by the trial team who did the research. We have not analysed the data ourselves.

Recruitment start:

Recruitment end:

How to join a clinical trial

Please note: In order to join a trial you will need to discuss it with your doctor, unless otherwise specified.

Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Chief Investigator

Dr Adam Mead

Supported by

Cell Therapeutics Inc (CTI)
NIHR Clinical Research Network: Cancer

If you have questions about the trial please contact our cancer information nurses

Freephone 0808 800 4040

Last review date

CRUK internal database number:


Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Last reviewed:

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