COSMOS: a phase 2 trial testing idelalisib and a new antibody drug MOR00208 in people with relapsed and refractory chronic lymphocytic leukaemia (CLL) or small lymphocytic lymphoma (SLL)

This trial is testing whether the combiination of idelalisib and a new antibody treatment is safe and effective for treating people with chronic lymphocytic leukaemia (CLL) or small lymphocytic lymphoma (SLL) who have already had ibruitnib or a similar drug.

Purpose of trial

The aim of this trial is to see if the combination of idelalisib and a new antibody treatment called MOR00208 can help people with CLL or SLL that has relapsed (come back) or is refractory (does not respond well to treatment).

You can only enter this study if your most recent treatment included a type of cell signal blocker called a ‘Bruton’s tyrosine kinase (BTK) inhibitor’, for example ibrutinib.


Idelalisib is a newer, targeted drug that is starting to be used for some people with lymphoma. It is a type of cell signal blocker called a PI3K inhibitor.

MOR00208 is an experimental treatment. It is an antibody that targets a protein called CD19 found on B lymphocytes (B cells), which are the cells that are abnormal in CLL and SLL.

Everyone in this trial receives both idelalisib and MOR00208. Treatment is given in 4-week cycles:

  • Idelalisib is taken by mouth twice a day, every day.
  • MOR00208 is given by intravenous infusion (into a vein). You have it once a week for the first 3 cycles, except for the first week of cycle 1 when you have it twice, on Day 1 and Day 4. You then have it once every 2 weeks for the next 3 cycles, followed by once every 4 weeks for all subsequent cycles.

The number of cycles of treatment you have depends on how you are responding to treatment.

Who can enter

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

Around 120 people are needed for this trial.

You may be able to enter if

  • You have CLL or SLL that has relapsed while receiving a BTK inhibitor or that was refractory to a BTK inhibitor.
  • Your most recent treatment included a BTK inhibitor alone or in combination with other treatments and you received this treatment for at least 1 month.
  • You need more treatment.
  • Your lymphoma is measurable by the tests used in the trial.
  • You are well enough to look after yourself and are up and about more than 50% of your waking hours, even if you are not well enough to work.
  • Your blood counts have fully recovered if you have had a stem cell transplant .
  • You and your partner are willing to use reliable contraception if there is any chance of you or your partner becoming pregnant.
  • Your blood and other health test results are satisfactory.
  • You are 18 or over.

You will not be able to enter if

  • You have a type of lymphoma other than CLL or SLL.
  • Your CLL or SLL has transformed (changed) into a more aggressive type of lymphoma, for example Richter’s transformation.
  • You have low blood counts.
  • You’ve had any other treatment in the 14 days before starting the trial treatment, including anti-cancer treatment, steroid treatments above 20 mg/day prednisone, or a live vaccine (except flu or pneumoccal vaccines).
  • You have been treated with a similar drug before, including anti-CD19 antibodies or a PI3K inhibitor.
  • You have previously had a bad reaction to a similar drug or any of the ingredients.
  • You have not recovered sufficiently from the side effects of your previous treatment.
  • You have certain bowel or lung problems, including ulcerative colitis, Crohn’s disease, chronic diarrhoea, severe chronic obstructive pulmonary disease (COPD), pulmonary emphysema or drug-induced pneumonitis.
  • You have any other health problems that your doctor thinks make it unsafe for you to take part in the trial.

Further information

More information about this trial is available at