Research projects

Objective 1. To investigate preclinically the efficacy and mechanism of action of immunotherapy agents in MM. Ex vivo and in vivo studies were carried out to complement the in vitro studies performed during the previous year. Specifically, bone marrow samples from MM patients were cultured ex vivo with the combination of EDO-S101 + daratumumab and we observed that the combination significantly eliminated more tumor cells than individual treatments. Moreover, the toxicity over healthy lymphocytes was not different from that of EDO-S101 (the most toxic of individual treatments). Finally, the double combination delayed tumor growth and significantly increased the survival in comparison with individual treatments in a plasmacytoma model in NSG mice humanized with NK cells.

Objective 2. To characterize the immune system of MM patients at different stages of the disease as well as the influence of different immunotherapy treatments. On the one hand, the immune profile of 17 patients included in the GEM-Pembresid clinical trial was analyzed. Pembrolizumab reduced the percentage of NK cells in peripheral blood at cycle 3. Also, in the early progressors, a significantly lower expression of PD1 in CD8+ effector memory T cells was observed.

On the other hand, our results suggest that clarithromycin in combination with lenalidomide and dexamethasone in MM patients (GEM-Claridex clinical trial) exerts suppressor effects on the immune system, mainly on NK cells and CD8+ T lymphocytes. This suggests the necessity of adjusting drugs doses, especially for dexamethasone.

Objetivo 3. To analyze the mechanisms of resistance to immunotherapy treatments. In our model of resistance to daratumumab (RMOLP-8), 4 miRNAs downregulated in resistant cells were identified. Among them, miR-125a-5p was especially interesting since it has been previously described as a Bcl-2 regulator, and this antiapoptotic protein, which is overexpressed in RMOLP-8 cells, could be implicated in the resistance mechanism.

The standardization of the protocol to perform genome-wide CRISPR-Cas9 knockout screens was also carried out. These screens will be applied both to MOLP-8 cells (daratumumab sensitive) to identify those genes whose elimination confers resistance and to RMOLP-8 cells (daratumumab resistant) to identify genes whose elimination reverses resistance.