The present invention concerns a method for the identification of the presence or absence of cancer cells in a biological sample, more particularly a method for the identification of the susceptibility or resistance to a treatment with CD20 agonists of cancer cells in a biological sample, said methods comprising determining the level of expression of the gene Cyclon in said cells and comparing said level of expression to the level of expression in a non-cancer cell, wherein a level of expression higher than the level of expression in a non-cancer cell is an indication of the presence of a cancer cell, more particularly an indication of cancer cells with a resistance to treatment with antagonists. The invention also concerns kits for the determination of a level of expression of the Cyclon gene in a biological sample, a method for the identification of Cyclon expression antagonists, as well as methods for treating patients in need thereof with CD20 agonists when the patients are identified to be susceptible to such a treatment and/or treating patients in need thereof with a combination of a Cyclon inhibitor and a CD20 agonists.
