Synergistic Drug Combinations Prevent Drug Resistance In Anaplastic Large Cell Lymphoma Preclinical Models.

Abstract Neoplastic cells are characterized by genetic instability, leading to the random accumulation of mutations in different tumor subpopulations, which therefore respond differently to treatments. Given the average mutational rate of tumors, the probability to acquire resistance to a single drug usually exceeds the number of cells present at diagnosis, making drug resistance a fact in most cases. Statistically, the chance of a cell being resistant to two simultaneous treatments is much lower, suggesting that drug combinations may help prevent resistance. Anaplastic large cell lymphoma (ALCL) is an aggressive type of Non-Hodgkin Lymphoma, characterized by expression of the NPM/ALK oncogenic fusion tyrosine kinase. ALK+ ALCL patients resistant or relapsed (R/R) to front-line chemotherapy have a very poor prognosis. The therapeutic activity of the ALK inhibitor crizotinib has been shown in patients with R/R ALK+ ALCL. However, 30-40% of patients develop resistance to crizotinib monotherapy and relapse within short time, leaving no further therapeutic option than bone marrow transplant, when feasible. This highlights the need to identify new first-line therapies for high-risk patients.We explored the potential of upfront drug combinations to prevent the rise of resistant disease, in vitro and in vivo. Crizotinib was combined with CHOP chemotherapy, an epigenetic drug (decitabine), another targeted inhibitor (trametinib- MEK inhibitor), or a second-generation ALK inhibitor. ALK+ ALCL cells were kept in culture for ~100 days in the presence of different single or combined drugs. We found that in most cases, combined treatments were more effective than single agents in the long-term control of cells expansion. Upon further functional characterization using quantitative PCR and western blot, we found that combination treatments upregulated cell cycle inhibitors and pro-apoptotic genes as well as modulated survival factors to induce deeper inhibition of oncogenic signalling and higher rates of apoptosis. Crizotinib+decitabine combination treatment promoted downregulation of DNMT1 and increase of TGFB1, both of which indirectly affect cell cycle progression. In murine model, crizotinib+decitabine significantly delayed tumour growth, compared to single treatments. Our results indicate that combining a selective drug with a less specific anticancer agent, which allows unspecific killing of resistant clones that might potentially arise, would be beneficial.In conclusion, our data suggest that a polypharmacology approach combining ALK inhibition with other agents could be a valuable therapeutic option for ALK+ ALCL patients, to prevent relapses and improve outcomes. Citation Format: Geeta G. Sharma, Giulia Arosio, Matteo Villa, Mario Mauri, Marina Zappa, Vera Magistroni, Monica Ceccon, Sara Redaelli, Ilaria Crespiatico, Diletta Fontana, Cristina Mastini, Anna Garbin, Federica Lovisa, Lara Mussolin, Rocco Piazza, Carlo Gambacorrti-Passerini, Luca Mologni. Synergistic drug combinations prevent drug resistance in anaplastic large cell lymphoma preclinical models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1113.