APR 10, 2018 5:24 PM PDT

'Melting Away' Chronic Lymphocytic Leukemia (CLL)

WRITTEN BY: Nouran Amin

Chronic lymphocytic leukemia (CLL) is a form of cancer that that first occurs in the cells that become certain white blood cells (called lymphocytes) which present in the bone marrow, later the cancer spreads to the blood.

In CLL, the leukemic cells progress very slowly and many individuals don't appear to have any symptoms for at least a few years. However, as the cancer continues to progress, the cells may reach other parts of the body, including the lymph nodes, liver, and spleen.A new oncology drug, Venetoclax, which was developed to treat two types of blood cancer now holds the potential to replace chemotherapy according to lead researcher John Seymour from the Peter MacCallum Cancer Centre (PMCC) in Victoria, Australia

In a large clinical trial, 389 patients across 20 countries diagnosed with chronic lymphocytic leukemia (CLL) and who had previously been treated and then relapsed were given venetoclax in combination with a standard immunotherapy drug known as rituximab, or just rituximab on its own. The results of the clinical study showed that for at least 15 months, 78% of patients after the treatment.

When a patient relapses, CLL is untreatable. However, during the clinical trial, nearly 85% the patients who were treated with venetoclax in combination with rituximab were measured to have a few to non-detectable leukemic cells in comparison to just 36% of those patients who received the standard immunotherapeutic. “That venetoclax is able to produce such dramatic results in this hard-to-treat patient group is remarkable and has led to much excitement among blood cancer clinicians globally and the research community particularly in Melbourne where this drug was pioneered,” says Seymour. “The data shows venetoclax should replace chemotherapy altogether in patients with advanced forms of CLL—a practice-changing result which will rapidly translate into the standard of care globally.”

High-power magnification (1000x) of a blood smear showing chronic lymphocytic leukemia. Image Source: MARY ANN THOMPSON/WIKIMEDIA

During a second clinical trial, by PMCCC lead researcher Constantine Tam, venetoclax was given to previously treated and relapsed Mantle Cell lymphoma (MCL) patients in combination with the immunotherapeutic ibrutinib.

Similar to CLL, there is no cure for relapsed MCL patients. However, it is important to note that MCL is more rare and aggressive than CLL. “It’s unprecedented that we’re seeing such deep responses in a such a high proportion of patients. These drugs will almost certainly replace chemotherapy going forward. It could be game-changing if these responses are durable,” says Sunil Iyengar, who wasn't involved in the studies but a consultant hemato-oncologist at the Royal Marsden NHS Foundation Trust in the U.K.

The development of Venetoclax was based on a landmark discovery by investigators at the Walter and Eliza Hall Institute in Melbourne. The discovery was a protein now called BCL-2 that works to promote the survival of cancerous cells.

“Venetoclax selectively targets BCL-2, essentially causing cancerous cells to simply melt away, in many instances,” says clinical haematologist, Andrew Roberts researcher at Walter and Eliza Hall Institute.

Sources: The New England Journal of Medicine, Newsweek

About the Author
Doctorate (PhD)
Nouran is a scientist, educator, and life-long learner with a passion for making science more communicable. When not busy in the lab isolating blood macrophages, she enjoys writing on various STEM topics.
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