A trial of pembrolizumab and rituximab for Waldenstrom's macroglobulinaemia (PembroWM)

Please note - this trial is no longer recruiting patients. We hope to add results when they are available.

Cancer type:

Blood cancers
Non-Hodgkin lymphoma




Phase 2

This trial is looking at pembrolizumab and rituximab for Waldenstrom’s macroglobulinaemia (WM). It is for people whose WM has come back after treatment or treatment has stopped working.

More about this trial

Waldenstrom’s macroglobulinaemia Open a glossary item (WM) is a slow growing type of non-Hodgkin lymphoma Open a glossary item (NHL). 

Doctors treat WM with rituximab on its own or in combination with other chemotherapy drugs or targeted cancer drugs Open a glossary item.

Sometimes WM can come back during treatment. This is known as refractory WM. It can also come back after treatment has finished. This is known as relapsed WM. Researchers are looking for new treatments to help people in these situations. 

Pembrolizumab is an immunotherapy drug. It works by helping the immune system find and kill cancer cells. We know from previous clinical trials that pembrolizumab could help people with WM. 

Rituximab is a monoclonal antibody

Researchers think the combination of pembrolizumab and rituximab might help people with WM that has come back or treatment has stopped working.

The main aims in this trial are to find out:

  • how well pembrolizumab and rituximab works 
  • how safe this combination is
  • what the side effects are
  • how it affects quality of life Open a glossary item

Who can enter

The following bullet points list the entry conditions for this trial. Talk to your doctor or the trial team if you are unsure about any of these. They will be able to advise you. 

Who can take part

You may be able to join this trial if all of the following apply. You:

  • have had at least 1 type of treatment for Waldenstrom’s macroglobulinaemia (WM) 
  • have WM that continued to grow during treatment or came back after treatment had finished
  • have WM that can be measured 
  • have satisfactory blood test results
  • are up and about, can care for yourself but might not be able to work (performance status 0, 1 or 2)
  • are willing to use reliable contraception during treatment. Women should continue to use it for a year after. Men should use it for 4 months after. This is if there is any chance you or your partner could become pregnant.
  • are at least 18 years old

Who can’t take part

Cancer related
You cannot join this trial if any of these apply. You:

  • have WM that has spread to the brain or spinal cord 
  • have had rituximab and the WM got worse during treatment or within 6 months after finishing treatment
  • have had another cancer treatment within 4 weeks of agreeing to join this trial apart from certain targeted drugs Open a glossary item. These drugs are called BTK inhibitors such as ibrutinib. 
  • have had another treatment that affects the T cells Open a glossary item such as Campath within 3 months of starting treatment
  • have another cancer that is getting worse or needs treatment. This does not include successfully treated non melanoma skin cancer Open a glossary item. And it doesn’t include in situ carcinoma Open a glossary item of the cervix.

Medical conditions
You cannot join this trial if any of these apply. You:

  • have had heart problems Open a glossary item in the past 6 months. This includes a heart attack, angina that isn’t well controlled congestive cardiac failure or a heart rhythm that needs treatment.
  • have had a stroke, mini stroke (TIA) or similar in the past 6 months
  • have an infection that needs treatment
  • have an autoimmune disease Open a glossary item. This does not include type 1 diabetes or thyroid problems controlled by medication. Nor does it include skin problems such as vitiligo, psoriasis, hair loss (alopecia). It also doesn’t include a drop in platelets Open a glossary item thought to be caused by Waldenstrom’s macroglobulinaemia.
  • had a condition where your red blood cells Open a glossary item breakdown (haemolytic anaemia)
  • have inflammation of the lining of the bowel (colitis) that isn’t caused by an infection
  • had inflammation of the lungs not caused by an infection that was treated with steroids or you have inflammation of the lungs (pneumonitis)
  • have had an experimental drug within 4 weeks of starting treatment
  • have hepatitis B or hepatitis C 
  • have HIV
  • have major surgery within 4 weeks of agreeing to join the trial
  • have had a drug similar to pembrolizumab or rituximab
  • have had a bone marrow transplant using someone else’s bone marrow (allogeneic transplant Open a glossary item
  • have had an organ transplant Open a glossary item and are taking medication to damp down the immune system
  • have an immune system Open a glossary item that isn’t working well
  • are taking medication such as steroids that damps down the immune system. So you can’t have taken it within 7 days of starting treatment. This doesn’t include nasal sprays, inhalations, creams, steroid injections that affect only one area of the body.  And you can have taken a low dose of steroids, that is up to 10mg a day for 5 days of steroid tablets. 
  • are having treatment that affects your whole body for an ongoing (chronic) infection
  • have any other medical condition or mental health problem that the trial team or your doctor think could affect you taking part

You cannot join this trial if any of these apply. You:

  • are allergic to pembrolizumab, rituximab, another drug like rituximab or any of their ingredients
  • have a live vaccine Open a glossary item or live attenuated vaccine within 30 days of starting treatment
  • are pregnant or breastfeeding

Trial design

This is a phase 2 trial. The trial team need 42 people to join. Everyone has pembrolizumab and rituximab. 

You have pembrolizumab as a drip into a vein. You have it once every 3 weeks. 

You have rituximab as a drip into a vein. You have it once a week for 4 weeks. And then once every 12 weeks.

Your doctor checks how well treatment is working at:

  • 12 weeks
  • 24 weeks
  • 1 year

You have treatment for a year as long as it is working and the side effects aren’t too bad.

You give some extra blood samples when you join and during the trial. When you have a bone marrow test Open a glossary item the trial team take a small piece of the bone marrow sample Open a glossary item

The team ask to take a small piece of the lymph node tissue (biopsy Open a glossary item) if your cancer has spread to the lymph nodes Open a glossary item. You give this when you join the trial. 

Researchers use these samples to find out more about Waldenstrom’s macroglobulinemia and the treatment. 

Quality of life 
You fill in a questionnaire when you join the trial and twice more during the trial. The questions ask about:

  • any side effects 
  • any symptoms you have
  • how the treatment affects your daily life

This is a quality of life questionnaire

In the event of pregnancy
During the trial if you or your partner become pregnant you stop treatment.

And the trial team want to monitor any pregnancies that happen during the trial or after. They collect this information during the pregnancy and for 8 weeks after. 
Women who become pregnant during treatment or within a year of stopping treatment, should tell their doctor or the trial team. 

For men, if your partner becomes pregnant during treatment or in the 4 months after treatment has finished, tell your doctor or the trial team. 

You or your partner don’t have to agree to have the pregnancy monitored by the trial team.

Hospital visits

You see the doctor to have some tests before taking part. These include:

  • physical examination Open a glossary item
  • blood tests
  • urine test including a pregnancy test if applicable 
  • heart trace (ECG Open a glossary item
  • CT scan
  • bone marrow test

You have treatment at the hospital on the day ward. During treatment you see the doctor for the following tests:

  • physical examination
  • blood tests
  • urine test including a pregnancy test if applicable
  • heart trace

You have these before each treatment and at:

  • 12 weeks
  • 24 weeks
  • 52 weeks

You have a bone marrow test at weeks 24 and 52. You also have a CT scan if needed.

You see the doctor at 2 months and then every year after finishing treatment. 

A member of the trial team phones you 5 months after finishing treatment to talk about any side effects you might have.

Side effects

The trial team monitor you during treatment and afterwards. Contact your advice line or tell your doctor or nurse if any side effects are bad or not getting better. 

You have a contact card from the trial team with the number to call. You should carry this card with you all the time. And when you go to the GP or hospital show them the card. In case they need to contact the trial team. 

Pembrolizumab and rituximab can affect the immune system. They may cause inflammation in different parts of the body which can cause serious side effects. These could happen during treatment, or some months after treatment has finished. Rarely, these side effects could be life threatening. Your doctor or nurse can explain what these side effects are, the risk of them happening and what to look out for.

If you have any of these side effects, you should tell the doctor or nurse as soon as possible that you are on or have been on an immunotherapy.

The most common side effects of pembrolizumab and rituximab include:

  • tiredness and feeling weak (fatigue)
  • a drop in blood cells causing an increased risk of infection and tiredness
  • a reaction during or just after having treatment (infusion reaction) –signs and symptoms include pain at the injection site, shaking, chills, fever, shortness of breath, wheezing, itching, rash, hives, feeling like passing out, dizziness, flushing, tummy (abdominal) pain
  • diarrhoea
  • feeling sick
  • infection
  • high temperature (fever) and chills
  • headache
  • rash, itching
  • hair loss
  • swelling under the skin

We have more information about:

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 Jaimal Kothari

Supported by

University College London (UCL)
Merck, Sharp & Dohme
CRUK & UCL Cancer Trials Centre

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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