Hairy cell leukemia (HCL) does not usually respond to chemotherapy. Most people with HCL have
a BRAF gene mutation. This can increase the growth of cancer cells. Vemurafenib has been
tested to treat these people. However, researchers think a combination of drugs might work
To test if treatment with a combination of encorafenib and binimetinib in BRAF mutant
HCL is more effective than treatment with vemurafenib.
People ages 18 and older with BRAF mutant HCL that did not respond to or came back after
Participants will be screened with:
Bone marrow biopsy: A needle will be injected through the participant s skin and into a bone
to remove liquid.
Blood and urine tests
Heart and lung function tests
CT or MRI scan: Participants will lie in a machine that takes pictures of the body. They may
have a contrast agent injected into a vein.
Participants will take the study drugs by mouth in 28-day cycles. They will take encorafenib
daily. They will take binimetinib twice daily. They will keep a pill diary.
Participants will take their temperature daily.
Participants will have at least 1 visit before each cycle. Visits will include repeats of
some screening tests. They will also include abdominal ultrasounds, exercise stress tests,
and skin evaluations.
Participants may continue treatment as long as their disease does not get worse and they do
not have bad side effects.
About a month after their last dose of treatment, participants will have a follow-up visit.
Then they will have annual follow-ups....
Hairy cell leukemia (HCL) is an indolent B-cell leukemia comprising 2% of all leukemias,
or approximately 1900 new cases/year in the US. The nucleoside analogs cladribine and
pentostatin are highly active as monotherapy with complete remission (CR) rates of 80 to
90%. However, there is no cure from chemotherapy and patients eventually relapse with
worse efficacy and cumulative toxicity (stem cell damage and neuropathy) with each
repeated chemotherapy course.
About 90% of classic HCL patients have the BRAF V600E mutation, which leads to
Rasindependent activation of the MAPK pathway, causing increased phosphorylation
(hyperactivation) of MEK, followed by ERK, therefore promoting the proliferation and
The BRAF inhibitor, vemurafenib, when used as a single agent for the treatment of HCL
achieved high response rate with CR rate of 38% in 50 patients reported from 2 trials,
however, treatment was limited to several months and responses lacked durability, with
median CR duration of 19 months in 1 trial. In this trial, 100% of the CRs were positive
for minimal residual disease (MRD) by immunohistochemistry (IHC), and failure to
eradicate MRD after several months of vemurafenib likely lead to the lack of CR
In a recent trial of combined inhibition of BRAF and MEK using dabrafenib and trametinib
treatment, 49% of 41 evaluable patients achieved CR, and MRD was eradicated in 15% of
patients on this trial. At NIH, we enrolled a total of 28 HCL patients on this trial and
achieved a CR rate of 68% amongst our patients by managing toxicity and allowing
patients to remain on treatment.
A major challenge in the long-term treatment of HCL patients with dabrafenib and
trametinib is managing fever, which has necessitated long-term or intermittent steroids
use for most patients.
In the COLOMBUS trial, the combination of the BRAF inhibitor, encorafenib and the MEK
inhibitor, binimetinib was found to be superior to vemurafenib for BRAF V600E+ melanoma
with respect to PFS and OS and was well tolerated with low rates of toxicities including
To our knowledge, neither encorafenib nor binimetinib has been tested in HCL, but the
low rate of pyrexia with encorafenib plus binimetinib in melanoma suggests that this
combination may be well tolerated in HCL.
-To determine if treatment with combination encorafenib and binimetinib in BRAF V600 mutant
+HCL is associated with a CR rate which exceeds that of vemurafenib.
BRAF V600 mutant HCL with at least 1 prior purine analog treatment
Need for treatment, as evidenced by any one of the following: ANC <1 x10(3)/mcL, Hgb
<10g/dL, Platelet count <100 x10(3)/mcL, leukemia cell count >5 x10(3)/mcL, symptomatic
splenomegaly, enlarging HCL mass > 2cm in short axis
Greater than or equal to 18 years of age
No uncontrolled infection, cardiopulmonary dysfunction, or secondary malignancy
No chemotherapy, immunotherapy, investigational agent or radiotherapy within 4 weeks
prior to the start of study treatment.
Phase 2 trial, single arm, non-randomized trial to determine if the combination of
encorafenib and binimetinib achieves a CR rate in HCL which is historically higher than
that of vemurafenib.
Simon optimal 2-phase design will be used to rule out an unacceptable CR rate of 35% in
favor of an improved 55% CR rate.
Initially 12 evaluable patients will be enrolled. If 5 or more achieve CR, then accrual
will continue to a total of 32 evaluable patients
Encorafenib will be given at a dose of 450mg QD and binimetinib at a dose of 45mg BID
for as long as patients can continue dosing chronically without significant toxicity
If you are confirmed eligible after full screening, you will be required to understand and sign the informed consent if you decide to enroll in the study. Once enrolled you may be asked to make scheduled visits over a period of time.
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