Suspect eliminated as a therapeutic target in B cell lymphoma

Walter and Eliza Hall Institute researchers have narrowed the focus on which survival proteins are important for the survival of B cell lymphomas, eliminating the protein BCL-W from the "suspect list."

Using gene editing technology, the research team showed that human B cell lymphoma cell lines can survive without BCL-W—dismissing this protein as a potential therapeutic target for these particular B cell lymphomas. The discovery upends earlier speculation that BCL-W could be an important survival factor for B cell lymphomas, and will focus future research efforts on more important targets.

The research, led by Dr. Gemma Kelly and Dr. Sarah Diepstraten, was published in the journal Blood Advances.

Lymphoma survival factors

BCL-W is a member of the BCL-2 protein family, and promotes cancer cell survival by inhibiting apoptotic cell death. Other pro-survival members of the BCL-2 family, including the proteins BCL-2 and MCL-1, have shown promise as targets for anti-cancer drugs, particularly for certain leukemias and lymphomas.

Dr. Kelly said that recent research from other groups showed that many B cell lymphomas had increased levels of BCL-W, suggesting that this protein may promote cancer cell survival.

"This led to speculation that drugs targeting BCL-W could be useful for treating B cell lymphomas," she said.

Eliminating a suspect

To investigate whether inhibiting BCL-W could be effective in treating B cell lymphomas, the team reduced the amount of BCL-W protein within B cell lymphoma cell lines.

Dr. Diepstraten said that in the B cell lymphoma cell lines tested, losing BCL-W did not impact cell survival. "We showed BCL-W was not required by these lymphoma cells, suggesting that drugs targeting BCL-W would not be effective treatments for all B cell lymphomas," Dr. Diepstraten said.

"We also investigated the possibility that high levels of BCL-W in lymphomas might cooperate with other related survival proteins, such as BCL-2 or MCL-1, to promote survival," she said. "However, this was not the case: loss of BCL-W did not sensitize lymphoma cells to drugs that inhibit BCL-2 or MCL-1."

Shifting focus

Dr. Kelly said the results showed that, at least for certain B cell lymphomas, targeting BCL-W should not be a priority for future research and drug development. "It is likely that other pro-survival proteins are much more important in these diseases," she said.

"BCL-W is considered to be a particularly appealing therapeutic target because it is not required for the function of most normal (non-cancerous) cells in the body, so we would not expect drugs targeting BCL-W to have significant side-effects.

"While BCL-W may not be a critical survival factor for B cell lymphomas, it is possible that BCL-W may contribute to the survival or drug resistance of other types of cancer—meaning that BCL-W inhibitors could be relevant in these cases," Dr. Kelly said.