GO29781: a phase 1/1b trial testing mosunetuzumab, on its own or with atezolizumab, in people with B-cell non-Hodgkin lymphoma or chronic lymphocytic leukaemia (CLL) that has come back or has not responded to treatment

This is a phase 1 (early phase) trial of an experimental treatment. Little is known about the safety and effectiveness of this treatment. You might not benefit from the treatment, but the trial will give important information about this new treatment, which could help other people in the future.

Purpose of trial

The aim of this trial is to establish the safety, and work out the best dose, of a new treatment called mosunetuzumab, on its own or in combination with atezolizumab, for people with B-cell non-Hodgkin lymphoma or chronic lympocytic leukaemia (CLL) that has come back (relapsed) or not responded (refractory) after treatment.


Participants are assigned to receive one of the following treatments:

  • mosunetuzumab on its own
  • mosunetuzumab and atezolizumab.

You can’t choose which treatment you have and neither can your doctor. Your doctor tells you which treatment you are having and you are given information about it.

Mosunetzumuab is given either through a drip (intravenous infusion) or as an injection just underneath your skin (subcutaneous injection). Atezolizumab is given through a drip. You have treatment every 21 days. You have up to 17 cycles of treatment.

Mosunetuzumab is a type of antibody called a ‘T-cell bispecific antibody’ (TCB). Most antibody treatments attach to one target protein but TCBs can attach to two targets on different cells (they are ‘bispecific’). Mosunetuzumab attaches to a protein called CD20 on B cells and to a protein called CD3 on T cells. This brings your healthy T cells into close contact with the cancerous B cells, helping your immune system get rid of the cancer.

Atezolizumab is a checkpoint inhibitor that stops lymphoma cells hiding from your immune system. This allows your immune system to recognise and kill the lymphoma cells.

This trial is in two parts: 

  • Part 1 is to find out the highest safe dose of mosunetuzumab. This is done by ‘dose escalation’. Participants are treated with different, gradually increasing, doses of mosunetuzumab. The highest dose that doesn’t cause serious side effects is used in part 2 of the trial.
  • Part 2 is to test how well the highest safe dose of the study drugs works in people with lymphoma. People entering this part of the trial all have the same dose of mosunetuzumab.

Who can enter

Your consultant can give you advice on whether you might be suitable for this trial.

Around 665 people are needed for this trial globally.

You may be able to enter if:

  • You have a type of B-cell lymphoma or B-cell chronic lymphocytic leukaemia that is likely to make a protein called CD20. Your doctor can tell you if this is the case.
  • You have previously had at least one course of treatment for your lymphoma.
  • There are no other treatment options that are likely to improve your outlook.
  • You are well enough to take part in the trial.
  • Your blood and other health test results are satisfactory.
  • You are 18 or over.

You won’t be able to enter if:

  • You have any health problems that your doctor thinks might make it unsafe for you to have the trial treatment.
  • Your lymphoma is in your central nervous system (CNS; brain and spinal cord).
  • You have an autoimmune disease (except controlled hypothyroidism, lymphoma-related immune thrombocytopenic purpura [ITP], or haemolytic anaemia).
  • You have HIV, hepatitis C or hepatitis B.
  • You are taking or have taken certain other drugs. (For some cancer treatments, there is a minimum gap between having the treatment and starting the trial, ranging from 2 weeks to 100 days. The trial investigator can tell you about this.)
  • You had any live vaccines in the 4 weeks before the trial.
  • You have ever had an allogeneic (donor) stem cell transplant or any organ transplant.
  • You are pregnant or breastfeeding.

Further information

More information about this trial is available at clinicaltrials.gov/ct2/show/study/NCT02500407