Leukemia
Update on Idelalisib + Rituximab in
Relapsed and Elderly CLL Patients
The combination of idelalisib with rituximab prolonged
progression-free survival (PFS) for patients with relapsed
chronic lymphocytic leukemia (CLL), according to an oral
presentation at the 56th ASH Annual Meeting.
In frail patients with relapsed CLL – especially those with adverse
prognostic factors such as chromosome 17p deletion or TP53 gene
mutations – there is an unmet need for more effective therapies,
noted lead study author Jeffrey P. Sharman, MD, in his presentation
of the results. “Patients with CLL who are considered inappropriate
candidates for traditional chemotherapy can derive substantial benefit from the addition of idelalisib to rituximab,” he added.
Idelalisib, a first-in-class, targeted, oral inhibitor of PI3K delta,
a protein that is over-expressed in many B-cell malignancies, was
recently approved by the FDA in combination with rituximab for
treatment of relapsed CLL.
“There have been other PI3K drugs in development affecting all of the isoforms, but what is unique about idelalisib is its
selectivity for the PI3K-delta isoform,” said Steven E. Coutre, MD,
in his discussion of the newly approved drug during the Special
Education Session on Newly Approved Drugs. “The delta isoform is not ubiquitously expressed, but seems to be limited to the
leukocytes.”
Idelalisib received FDA approval for the treatment of relapsed
chronic lymphocytic leukemia based on a results from a clinical
trial of 220 patients who were randomly assigned to receive idelalisib + rituximab or placebo + rituximab. The trial was stopped
early after investigators observed “a rather dramatic difference
between the two arms” in terms of progression-free survival (PFS),
noted Dr. Coutre: 10.7 months vs. 5.5 months with pla