Microambient immune tumoral en neoplàsies limfoides b

Resumen

The tumor immune microenvironment (TIME) plays a critical role in the early formation of tumors and their progression. Targeting the TIME has offered new therapeutic approaches and improved current ones in several cancers, including B-cell malignancies. Nonetheless, further investigation is needed in order to more deeply understand immune evasion mechanisms that lead to tumor progression and to design therapies that modulate the immune system more precisely. Here, our main objectives are to provide new insights into immune mechanisms that favor tumor progression and a pre-clinical rationale for the design of new therapeutic strategies with immunomodulatory potential. To accomplish these goals our study will focus on chronic lymphocytic leukemia (CLL) and primary central nervous system lymphoma (PCNSL). Mechanisms driving the progression of CLL from its early stages are not fully understood. This hampers detecting progression in advance and developing therapies that could intervene in the early stages. Although the limited acquisition of molecular changes suggests that CLL progression is not mainly driven by clonal evolution, a deeper analysis of the immune microenvironment that demonstrates immune variations over time that contribute to progression has not been performed. Hence, we longitudinally studied the immune and genetic landscapes of untreated progressing and non-progressing patients. Our results show that progressed CLL patients experience an increase in effector memory and terminally exhausted T-betmid/-EomeshiPDhi CD8+ T cells over time, not observed in non-progressing patients. In addition, T cells at progression acquire a distinct transcriptional profile. This is accompanied by enhanced immunosuppressive properties in leukemic cells at progression. We prove that progressed CLL cells are intrinsically more capable of inducing CD8+ T-cell exhaustion in T cells affected by CLL and healthy T cells by a mechanism dependent on soluble factors including IL-10. In addition, the reduced genetic changes we found by whole-exome sequencing in our cohort indicate these immune variations are fundamental for progression in CLL. Patients diagnosed with PCNSL often face dismal outcomes due to the limited availability of therapeutic options. PCNSL cells frequently have deregulated B-cell receptor (BCR) signaling, but its inhibition using ibrutinib only offers a brief effective response in PCNSL patients. Nonetheless, the BCR pathway can also be blocked by inhibiting the nuclear exportin XPO1 using selinexor. Selinexor is able to cross the blood–brain barrier and has shown positive clinical activity in a patient with refractory diffuse large B-cell lymphoma in the CNS. Accordingly, we evaluated the effects of selinexor alone and also combined it with ibrutinib in pre-clinical mouse models of PCNSL. Our analysis shows that selinexor blocks tumor growth and prolongs survival in a bioluminescent mouse model and its combination with ibrutinib further increases survival. We demonstrate that CNS lymphomas in mice are infiltrated by tumor-promoting M2-like macrophages expressing PD-1 and SIRPα. Moreover, the treatment with selinexor and ibrutinib favors an anti-tumoral immune response by shifting macrophage polarization toward an inflammatory phenotype and diminishing the expression of PD-1 and SIRPα in M2 tumor-associated macrophages.