Immunologic Characterization of Coronavirus Disease 2019 (COVID-19) Patients with Hematological Cancer: Biologic and Clinical Significance

Background: The immune system reacts to viral infection with cellular and humoral responses. Thus, myelo- and lympho-suppression caused by cancer itself as well as cytotoxic treatment may pose a challenge to COVID-19 patients with solid and hematological tumors, but severe events from initial onset of COVID-19 appear to be more frequent in blood malignancies vs other cancer types. Preliminary data showed lower neutrophil and lymphocyte counts in COVID-19 patients bearing hematological cancer, but there are conflicting results supporting that both worsening of lymphopenia during COVID-19 and its depth prior to infection had a beneficial impact on survival. Thus, greater knowledge on the immune status of hematological patients may be useful to optimize prevention, risk stratification and treatment strategies.

Aim: Analyze the immune status of COVID-19 patients with or without solid and hematological cancer.

Methods: We use multidimensional flow cytometry (MFC) to analyze immune profiles in peripheral blood samples of 515 COVID-19 patients at presentation. Data was analyzed with a semi-automated pipeline that performs batch-analyses of MFC data to avoid variability intrinsic to manual analysis, and unveils full cellular diversity based on unbiased clustering. In 14 cases, deep immunophenotyping of B- and T-cells was performed and six myeloid- and dendritic-cell subsets were FACSorted for transcriptome analysis using RNAseq.

Results: Of the 515 COVID-19 patients, 15 and 10 had solid and hematological tumors, respectively. Those with hematological cancer showed similar frequency of hospitalization than those with solid tumors (90% and 93%, respectively), which was modestly higher to that observed in persons without an active tumor (76%). By contrast, the frequency of hematological cases requiring intensive care (50%) and dying from COVID-19 (30%) was significantly higher to that observed in patients with no active tumor (5.5% and 4%, respectively), or with solid cancer (both 0%).

Based on semi-automated analysis of MFC data, we systematically quantified a total of 19 cell types in PB that included 6 myeloid and 13 lymphoid subsets. Patients with hematological malignancies displayed altered immune profiles with significantly decreased absolute numbers of classical and intermediate monocytes, immunoregulatory and cytotoxic NK cells, double-negative, double-positive, CD4 and CD56- γδ T cells, as well as of mature B cells when compared to those with no tumor.

Unsupervised hierarchical analysis of RNAseq data from basophils, myeloid and plasmacytoid dendritic cells, classical and non-classical monocytes and neutrophils showed considerable clustering of samples from hematological cases. Furthermore, a variable number of differentially expressed genes was found in all six cell types between COVID-19 patients with or without blood cancer. Genes related to NF-κB and STAT transcription factors as well as genes encoding toll-like receptors and proinflammatory interleukin receptors, all of which described to be implicated in the response and evasion of innate sensing by coronaviruses, were differentially expressed in many of these cell types. Deep phenotypic characterization of T- and B-cell compartments in PB of COVID-19 patients with (N = 4) or without (N = 10) hematological cancer showed that the relative distribution of antigen-dependent maturation stages within the T-cell compartment was generally similar between both groups. However, some hematological cases displayed profound alterations in virtually all of the 16 B-cell subsets analyzed, with a notorious reduction in memory B cells expressing IgG and IgA subclasses.

We next compared immune responses from presentation to last follow-up in COVID-19 patients with hematological cancer and favorable (N = 3) vs fatal (N = 3) outcome. Interestingly, we found opposite kinetics in myeloid cell types such as eosinophils and neutrophils, decreasing numbers of various T cell subsets, as well as lower mature B cells and circulating PCs at presentation together with a decrease in B cell counts in deceased cases.

Conclusions: Our study exposes for the first time that hematological patients show a constellation of immune alterations that could compromise the response to the infection caused by SARS-CoV-2, suggesting an association between impaired immune responses and poorer outcomes in COVID-19 patients with hematological malignancies.