<< Return to patient support page to view other webinars and forums
HCL Regional Patient Forum (West Coast)
March 30, 2022
The Hairy Cell Leukemia Foundation thanks Dr. Alan Saven of the Scripps Clinic in La Jolla, CA for presenting on HCL during our regional HCL patient forum. Below is a summary of the presentation and discussion.
How is HCL Diagnosed?
Hairy Cell Leukemia (HCL) comes from a mutated B-cell. The hairy cells, which have a hairy-like appearance, spread throughout the bone marrow. These mutated cells leave less room for healthy cells to grow.
There are specific biomarkers (B cell antigens) present on the hairy cells. These biomarkers are CD19, CD20, and CD22. HCL cells also have a strong expression of CD11c, CD25, and CD103.
Fifty years ago, it was difficult to diagnose HCL. Today, more sophisticated technology allows us to identify these protein patterns on the hairy cells and easily diagnose the disease.
In the past, peripheral blood trap stains were frequently used to diagnose HCL, however, this method was minimally accurate. Today, a bone marrow biopsy is important for the most accurate diagnosis. The biopsy helps to identify the BRAF V600E mutation which is present in virtually all cases of classic HCL. The BRAF mutation in HCL was first described about 10 years ago by a research group led by Dr. Enrico Tiacci in Italy. BRAF inhibitors (e.g., vemurafenib) used to treat diseases such as malignant melanoma can now be used in hairy cell leukemia.
So, the BRAF mutation has diagnostic and therapeutic implications. Patients who are newly diagnosed with HCL should request the BRAF test.
What are the initial treatment options for HCL?
Not all cases of HCL need to be treated right away. Many individuals can live with HCL in their bone marrow for decades as long as it does not negatively impact their health. So, a doctor may choose to observe the patient before initiating treatment.
Treatment should be considered when blood counts are abnormal: hemoglobin levels less than 11 g/dL, platelet counts less than 100,000 uL, or an absolute neutrophil count less than 1000/uL.
Some people with HCL may experience symptoms, such as an enlarged spleen or significant fatigue, that require immediate treatment for HCL.
If a patient requires treatment, three drugs have been approved in the United States for frontline therapy.
Interferon: Interferon was approved a few decades ago to treat HCL. However, it’s not used as frequently today because it doesn’t work as well as modern therapies. Interferon gives patients partial responses rather than complete responses.
Pentostatin: A standard dose of pentostatin is 4mg taken every other week for 3-6 months until maximum response.
Cladribine: A standard dose of cladribine (2CDA) is 0.085-0.1 mg, 2 hours a day for 5 days. Cladribine used to be given through continuous infusion for one week (7 days). With cladribine, you can get a deep, complete remission with only 1 week of therapy. Lowering the dose of cladribine is not advised and completing the full therapy is recommended.
Researchers have found that pentostatin and cladribine are more effective than interferon.
However, both medications are immunosuppressant, so patients should be cautious during treatment.
What are the treatment options for relapse?
No drug can completely cure this disease, but patients with HCL are expected to have normal life expectancies.
Relapses are common, because it is difficult for the medications approved for HCL to completely clean out the bone marrow. A significant number of patients have minimal residual disease (MRD) after completing treatment, despite having normal blood counts. Many patients have received cladribine plus rituximab, but it remains to be seen whether MRD is an important endpoint.
Drugs such as cladribine become less responsive over time, so switching from one medication to another may be more effective than repeating treatment with cladribine. Cladribine alone is very immunosuppressive. It can lower a patient’s immunity for 6 to 12 months. Combining cladribine with rituximab leads to the best chances of eliminating MRD. However, this combination can make patients immunocompromised for protracted periods of time.
There has been discussion about other options for treatment, particularly in the time of COVID, but for most people, cladribine remains the standard of care.
Filgrastim (neupogen) can be used to bring up white blood counts and reduce the risk of infection. Investigators have examined results of people with HCL who received cladribine and filgrastim, compared to people who received cladribine alone. The administration of filgrastim decreased the amount of time the patient had low white blood counts. However, the number of days with fever or number of days in the hospital were unaffected.
For relapsed patients, remission durations get shorter with multiple treatments of cladribine. Doctors can switch from cladribine to pentostatin, or from pentostatin to cladribine, to achieve a response.
Newer agents to treat HCL have been introduced. Most of these weren’t developed specifically for HCL, but investigators have found application for HCL.
Rituximab (anti-CD20):
Rituximab on its own does not work as well. It is generally used in combination with other agents. However, when cladribine and rituximab are combined, the immune system is suppressed for a longer period of time. In the time of COVID, it’s dangerous for patients be immunocompromised for protracted periods.
If cladribine and rituximab are given together, there are two options. A doctor can:
First give cladribine, wait a month, then give rituximab weekly for 4 weeks; or
Give rituximab at the same time as cladribine – administering rituximab weekly for 8 weeks.
Vemurafenib (BRAF inhibitor):
Vemurafenib can be combined with rituximab as well as with other drugs, including MEK inhibitors. When a patient has an active infection, cladribine and pentostatin must be avoided. Vemurafenib can be administered in place of the nucleoside analogs.
Moxetumomab pasudotox:
A chemo-free option for relapsed or refractory patients in the United States. Moxe can also be effective in combination with other medications.
Dr. Robert Kreitman at the National Cancer Institute developed the agent. It targets CD22 which is expressed on hairy cells and interferes with how the cell divides.
Moxe works reasonably well for patients who have failed other therapies, but it can be difficult to administer. Some patients experience Capillary Leak Syndrome, a rare side effect not seen with other agents prescribed to treat HCL. Patients receiving this treatment must consume vast amounts of water each day.
There are risks for second malignancies in patients with HCL. Patients with HCL are encouraged to get their annual examinations, including a colonscopy and skin checks, and to wear sunscreen and hats to protect their skin from the sun.
How to handle symptoms and stress?
Many symptoms can arise at the same time as a diagnosis of and treatment for HCL. Some of these symptoms can be due to everyday stress, so patients are encouraged to find healthy and effective methods to cope with stress.
We also thank everyone who participated in person or remotely on March 30th. We are holding these meetings to educate and empower, and to promote regional or local connections that can be supportive to patients during their journey with hairy cell leukemia. We encourage all patients to learn more about our patient registry and sign up. >>