The mitochondrial anti-apoptotic dependencies of hematologic malignancies: from disease biology to advances in precision medicine

Mitochondria are critical organelles in the regulation of intrinsic apoptosis. As a general feature of blood cancers, different anti-apoptotic members of the BCL-2 protein family localize at the outer mitochondrial membrane to sequester variable amounts of pro-apoptotic activators, and hence protect cancer cells from death induc-tion. However, the impact of distinct anti-apoptotic members on apop-tosis prevention, a concept termed anti-apoptotic dependence, differs remarkably across disease entities. Over the last two decades, several genetic and functional methodologies have been established to uncover the anti-apoptotic dependencies of the majority of blood cancers, inspiring the development of a new class of small molecules called BH3 mimetics. In this review, we highlight the rationale of targeting mito-chondrial apoptosis in hematology, and provide a comprehensive map of the anti-apoptotic dependencies that are currently guiding novel therapeutic strategies. Cell-extrinsic and -intrinsic mechanisms confer-ring resistance to BH3 mimetics are also examined, with insights on potential strategies to overcome them. Finally, we discuss how the field of mitochondrial apoptosis might be complemented with other dimen-sions of precision medicine for more successful treatment of ‘highly complex’ hematologic malignancies

The Evolving Knowledge on T and NK Cells in Classic Hodgkin Lymphoma: Insights into Novel Subsets Populating the Immune Microenvironment

Classic Hodgkin lymphoma (cHL) is a unique lymphoid neoplasm characterized by extensive immune infiltrates surrounding rare malignant Hodgkin Reed-Sternberg (HRS) cells. Different subsets of T and NK cells have long been recognized in the cHL microenvironment, yet their distinct contribution to disease pathogenesis has remained enigmatic. Very recently, novel platforms for high dimensional analysis of immune cells, such as single-cell RNA sequencing and mass cytometry, have revealed unanticipated insights into the composition of T- and NK-cell compartments in cHL. Advances in imaging techniques have better defined specific T-helper subpopulations physically interacting with neoplastic cells. In addition, the identification of novel cytotoxic subsets with an exhausted phenotype, typically enriched in cHL milieu, is shedding light on previously unrecognized immune evasion mechanisms. This review examines the immunological features and the functional properties of T and NK subsets recently identified in the cHL microenvironment, highlighting their pathological interplay with HRS cells. We also discuss how this knowledge can be exploited to predict response to immunotherapy and to design novel strategies to improve PD-1 blockade efficacy

Oncogenic Mutations of MYD88 and CD79B in Diffuse Large B-Cell Lymphoma and Implications for Clinical Practice

Simple SummaryA diagnosis of diffuse large B-cell lymphoma in our therapeutic era should be implemented by the definition of the cell of origin, additional immunohistochemistry (i.e., BCL2 and MYC), and by fluorescent in-situ hybridization. The next step, suggested by the seminary works we will discuss in this review, will be to implement the definition of sub-categories by the recognition of single gene mutations and pathways that may be targetable by newer drugs. We here describe the impact that MYD88 and CD79B activating mutations, two of the most frequent mutations in several DLBCL subtypes, may achieve in the next future in the diagnosis and therapeutics of such a relevant lymphoma subtype.Diffuse large B-cell lymphoma (DLBCL) is the most common non-Hodgkin's lymphoma in adults. Despite the recognition of transcriptional subtypes with distinct functional characteristics, patient outcomes have not been substantially altered since the advent of chemoimmunotherapy (CIT) twenty years ago. Recently, a few pivotal studies added to the disease heterogeneity by describing several activating mutations, which have been associated with disease presentation, B-cell function and behavior, and final outcome. DLBCL arises from antigen exposed B-cells, with the B-cell receptor (BCR) playing a central role. BCR-activity related mutations, such as CD79B and MYD88, are responsible for chronic activation of the BCR in a substantial subset of patients. These mutations, often coexisting in the same patient, have been found in a substantial subset of patients with immune-privileged (IP) sites DLBCLs, and are drivers of lymphoma development conferring tissue-specific homing properties. Both mutations have been associated with disease behavior, including tumor response either to CIT or to BCR-targeted therapy. The recognition of CD79B and MYD88 mutations will contribute to the heterogeneity of the disease, both in recognizing the BCR as a potential therapeutic target and in providing genetic tools for personalized treatment

Management of patients with lymphoma and COVID-19: Narrative review and evidence-based practical recommendations

Patients with hematologic malignancies can be immunocompromized because of their disease, anti-cancer therapy, and concomitant immunosuppressive treatment. Furthermore, these patients are usually older than 60 years and have comorbidities. For all these reasons they are highly vulnerable to infection with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and have an increased risk of developing severe/critical Coronavirus disease 2019 (COVID-19) compared to the general population. Although COVID-19 vaccination has proven effective in reducing the incidence of severe/critical disease, vaccinated patients with lymphoma may not be protected as they often fail to develop a sufficient antiviral immune response. There is therefore an urgent need to address the management of patients with lymphoma and COVID-19 in the setting of the ongoing pandemic. Passive immunization with monoclonal antibodies against SARS-CoV-2 is a currently available complementary drug strategy to active vaccination for lymphoma patients, while monoclonal antibodies and antiviral drugs (remdesivir, ritonavir-boosted nirmatrelvir, and molnupiravir) have proven effective in preventing the progression to severe/critical COVID-19. In this narrative review we present the most recent data documenting the characteristics and outcomes of patients with concomitant lymphoma and COVID-19. Our ultimate goal is to provide practice-oriented guidance in the management of these vulnerable patients from diagnosis to treatment and follow-up of lymphoma. To this purpose, we will first provide an overview of the main data concerning prognostic factors and fatality rate of lymphoma patients who develop COVID-19; the outcomes of COVID-19 vaccination will also be addressed. We will then discuss current COVID-19 prophylaxis and treatment options for lymphoma patients. Finally, based on the literature and our multidisciplinary experience, we will summarize a set of indications on how to manage patients with lymphoma according to COVID-19 exposure, level of disease severity and former history of infection, as typically encountered in clinical practice

An updated portrait of monocyte-macrophages in classical Hodgkin lymphoma

Classical Hodgkin lymphoma (cHL) is a unique neoplastic ecosystem characterized by a heterogeneous immune infiltrate surrounding the rare malignant Hodgkin Reed-Sternberg cells. Though less abundant than T-cells, tumor-infiltrating macrophages play a pivotal role in supporting HRS survival through cell-to-cell and paracrine interactions. Traditional immunohistochemistry based upon the M1-M2 dichotomy yielded controversial results about the composition, functional role and prognostic impact of macrophages in cHL. More recent studies exploiting single-cell technologies and image analyses have highlighted the heterogeneity and the peculiar spatial arrangement of the macrophagic infiltrate, with the most immunosuppressive subpopulations lying in close proximity of HRS cells and the most tumor-hostile subsets kept far away from the neoplastic niches. High-throughput analysis of peripheral blood mononuclear cells in cHL patients have also identified a novel, potentially cytotoxic, subpopulation predicting better response to PD-1 blockade. This review examines the phenotypic profile, spatial localization and clinical impact of tumor-infiltrating macrophages and circulating monocytes in cHL, providing an up-do-date portrait of these innate immune cells with possible translational applications

Bendamustine plus rituximab: is it a BRIGHT idea?

Flinn et al . have reported the results of the long-term follow-up for the BRIGHT trial, an international study which compared the efficacy and the safety of bendamustine plus rituximab (BR) with either rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) or rituximab plus cyclophosphamide, vincristine, and prednisone (R-CVP) for treatment-naive patients with indolent non-Hodgkin lymphoma (iNHL) or mantle-cell lymphoma (MCL)

Integration of B-cell receptor-induced ERK1/2 phosphorylation and mutations of SF3B1 gene refines prognosis in treatment-na\uefve chronic lymphocytic leukemia

ADP-ribosyl Cyclase 1; Disease Progression; Humans; Immunoglobulin Heavy Chains; Immunoglobulin Variable[no abstract available

Life-Threatening Protein-Losing Enteropathy Due To Human Cytomegalovirus Infection Upon Immunochemotherapy

Immunochemotherapy adverse events affecting the gastrointestinal tract usually consist of self-limiting nausea/ vomiting or diarrhoea, while bleeding and perforation are rare. A 42-year-old woman treated with bendamustine/ rituximab for splenic marginal zone lymphoma developed alife-threatening protein-losing enteropathy that was a diagnosis conundrum, ranging from drug-induced, immunemediated, neoplastic and infectious forms. Suspecting opportunistic viral infection but with unremarkable immunohistochemistry and peripheral blood tests, the diagnosis of Human Cytomegalovirus enteritis was made only by means of quantitative real-time polymerase chain reaction carried out on mucosal specimens. Steroid discontinuation and a prolonged course of antiviral therapy allowed the patient to overcome the critical phase and to achieve gradual normalisation of stool frequency, body mass index, laboratory tests lasting one year, while disappearance of mucosal viral load resulted soon evident. Human Cytom-egalovirus end-organ disease localised at the gastrointestinal tract is a serious condition whose prompt diagnosis and treatment prevents poor patients prognosis

MEK1/2 regulate normal BCR and ABL1 tumor-suppressor functions to dictate ATO response in TKI-resistant Ph+ leukemia

Resistance to tyrosine kinase inhibitors (TKIs) remains a clinical challenge in Ph-positive variants of chronic myeloid leukemia. We provide mechanistic insights into a previously undisclosed MEK1/2/BCR::ABL1/BCR/ABL1-driven signaling loop that may determine the efficacy of arsenic trioxide (ATO) in TKI-resistant leukemic patients. We find that activated MEK1/2 assemble into a pentameric complex with BCR::ABL1, BCR and ABL1 to induce phosphorylation of BCR and BCR::ABL1 at Tyr360 and Tyr177, and ABL1, at Thr735 and Tyr412 residues thus provoking loss of BCR's tumor-suppression functions, enhanced oncogenic activity of BCR::ABL1, cytoplasmic retention of ABL1 and consequently drug resistance. Coherently, pharmacological blockade of MEK1/2 induces dissociation of the pentameric MEK1/2/BCR::ABL1/BCR/ABL1 complex and causes a concurrent BCRY360/Y177, BCR::ABL1Y360/Y177 and cytoplasmic ABL1Y412/T735 dephosphorylation thereby provoking the rescue of the BCR's anti-oncogenic activities, nuclear accumulation of ABL1 with tumor-suppressive functions and consequently, growth inhibition of the leukemic cells and an ATO sensitization via BCR-MYC and ABL1-p73 signaling axes activation. Additionally, the allosteric activation of nuclear ABL1 was consistently found to enhance the anti-leukemic effects of the MEK1/2 inhibitor Mirdametinib, which when combined with ATO, significantly prolonged the survival of mice bearing BCR::ABL1-T315I-induced leukemia. These findings highlight the therapeutic potential of MEK1/2-inhibitors/ATO combination for the treatment of TKI-resistant leukemia