Individual HLA heterogeneity and its implications for cellular immune evasion in cancer and beyond

Structural and functional variability of human leukocyte antigen (HLA) is the foundation for competent adaptive immune responses against pathogen and tumor antigens as it assures the breadth of the presented immune-peptidome, theoretically sustaining an efficient and diverse T cell response. This variability is presumably the result of the continuous selection by pathogens, which over the course of evolution shaped the adaptive immune system favoring the assortment of a hyper-polymorphic HLA system able to elaborate efficient immune responses. Any genetic alteration affecting this diversity may lead to pathological processes, perturbing antigen presentation capabilities, T-cell reactivity and, to some extent, natural killer cell functionality. A highly variable germline HLA genotype can convey immunogenetic protection against infections, be associated with tumor surveillance or influence response to anti-neoplastic treatments. In contrast, somatic aberrations of HLA loci, rearranging the original germline configuration, theoretically decreasing its variability, can facilitate mechanisms of immune escape that promote tumor growth and immune resistance.The purpose of the present review is to provide a unified and up-to-date overview of the pathophysiological consequences related to the perturbations of the genomic heterogeneity of HLA complexes and their impact on human diseases, with a special focus on cancer

Comprehensive transcriptomic analysis of VISTA in acute myeloid leukemia: Insights into its prognostic value

The V-domain Ig suppressor of T-cell activation (VISTA) has been recognized as a critical negative regulator of antitumor immune response and is gaining growing interest as a potential pharmacological target in immunotherapy. This molecule is highly expressed in hematopoietic stem cells and myeloid compartment, and it has been found upmodulated in acute myeloid leukemia (AML). However, VISTA-associated immune features are relatively unexplored in myeloid malignancies. Herein, we aimed to explore whether this immune checkpoint regulator could play a role in the generation of an immune escape environment in AML patients. We characterized VISTA mRNA expression levels in leukemia cell lines and in large publicly available cohorts of specimens from bone marrow of healthy individuals and AML patients at diagnosis by deploying bulk and single-cell RNA sequencing. We also defined the correlations with leukemia-associated burden using results of whole-exome sequencing of AML samples at disease onset. We showed that VISTA expression linearly increased across the myeloid differentiation tree in normal hematopoiesis. Accordingly, its transcript was highly enriched in AML cell lines as well as in AML patients at diagnosis presenting with myelomonocytic and monocytic differentiation. A strong correlation was seen wit

Prognostic Significance of New Immunohistochemical Markers in Refractory Classical Hodgkin Lymphoma: A Study of 59 Cases

Although most classical Hodgkin lymphoma patients are cured, a significant minority fail after primary therapy and may die as result of their disease. To date, there is no consensus on biological markers that add value to usual parameters (which comprise the International Prognostic Score) used at diagnosis to predict outcome. We evaluated 59 patients (18 with primary refractory or early relapse disease and 41 responders) for bcl2, Ki67, CD20, TiA1 and c-kit expression by semi-quantitative immunohistochemical study and correlated the results with the response to treatment

KIR in Allogeneic Hematopoietic Stem Cell Transplantation: Need for a Unified Paradigm for Donor Selection

Allogeneic hematopoietic stem cell transplantation (aHSCT) is a lifesaving therapy for hematological malignancies. For years, a fully matched HLA donor was a requisite for the procedure. However, new immunosuppressive strategies have enabled the recruitment of viable alternative donors, particularly haploidentical donors. Over 95% of patients have at least two potential haploidentical donors available to them. To identify the best haploidentical donor, the assessment of new immunogenetic criteria could help. To this end, the clinical benefit of KIR genotyping in aHSCT has been widely studied but remains contentious. This review aims to evaluate the importance of KIR-driven NK cell alloreactivity in the context of aHSCT and explain potential reasons for the discrepancies in the literature. Here, through a non-systematic review, we highlight how the studies in this field and their respective predictive models or scoring strategies could be conceptually opposed, explaining why the role of NK cells remains unclear in aHCST outcomes. We evaluate the limitations of each published prediction model and describe how every scoring strategy to date only partly delivers the requirements for optimally effective NK cells in aHSCT. Finally, we propose approaches toward finding the optimal use of KIR genotyping in aHSCT for a unified criterion for donor selection

Comorbidities in transplant recipients with acute myeloid leukemia receiving low-intensity conditioning regimens: an ALWP EBMT study

Older age and a high burden of comorbidities often drive the selection of low-intensity conditioning regimens in allogeneic hematopoietic stem cell transplantation recipients. However, the impact of comorbidities in the low-intensity conditioning setting is unclear. We sought to determine the contribution of individual comorbidities and their cumulative burden on the risk of nonrelapse mortality (NRM) among patients receiving low-intensity regimens. In a retrospective analysis of adults (≥18 years) who underwent transplantation for acute myeloid leukemia in the first complete remission between 2008 and 2018, we studied recipients of low-intensity regimens as defined by the transplantation conditioning intensity (TCI) scale. Multivariable Cox models were constructed to study associations of comorbidities with NRM. Comorbidities identified as putative risk factors in the low-TCI setting were included in combined multivariable regression models assessed for overall survival, NRM, and relapse. A total of 1663 patients with a median age of 61 years received low-TCI regimens. Cardiac comorbidity (including arrhythmia/valvular disease) and psychiatric disease were associated with increased NRM risk (hazard ratio [HR], 1.54; 95% confidence interval [CI], 1.13-2.09 and HR, 1.69; 95% CI, 1.02-2.82, respectively). Moderate pulmonary dysfunction, though prevalent, was not associated with increased NRM. In a combined model, cardiac, psychiatric, renal, and inflammatory bowel diseases were independently associated with adverse transplantation outcomes. These findings may inform patient and regimen selection and reinforce the need for further investigation of cardioprotective transplantation approaches.</p

Outcomes of subsequent neoplasms after umbilical cord blood transplantation in Europe

Subsequent neoplasms (SNs) compromise long-term survivors after hematopoietic cell transplantation. We performed a retrospective analysis of SNs in 10 358 recipients of umbilical cord blood transplantation (UCBT) from 1988 to 2018. SNs developed in 233 patients and 84 were of pediatric age. Indications for UCBT were malignant hematological diseases in 199 patients (85%). Three groups of SNs were observed. Posttransplant lymphoproliferative disorders (PTLD) were reported in 145 patients in a median of 4 months after UCBT. Of these, 9 patients died from relapse, 83 from PTLD, and 24 from transplant-related causes. At last follow-up, 29 were alive; 5-year overall survival (OS) after PTLD diagnosis was 21%. Acute leukemia/myelodysplasia (AL/MDS) was diagnosed in 23 patients in a median of 28 months after UCBT and included 3 donor-cell AL. Four of 23 patients died from relapse of primary disease, 8 from progression of SNs, and 4 from TRM. Seven patients remain alive; the 5-year OS after AL/MDS diagnosis was 36%. Solid tumors (ST) were reported in 65 patients in a median of 54 months after UCBT. Most common tumor sites were lung, thyroid, bone, and soft tissue. A total of 33 patients died (26 owing to ST, 6 to relapse of primary disease, and 1 cause missing). At last follow-up, 32 of 65 patients were alive; the 5-year OS after the diagnosis of ST was 51%. In conclusion, despite their poor outcomes, SNs that occur after UCBT are extremely rare. Identification of risk factors and early detection may help to improve OS

Depletion of CD11c+ cells in the CD11c.DTR model drives expansion of unique CD64+ Ly6C+ monocytes that are poised to release TNF-α

Dendritic cells (DCs) play a vital role in innate and adaptive immunities. Inducible depletion of CD11c+ DCs engineered to express a high-affinity diphtheria toxin receptor has been a powerful tool to dissect DC function in vivo. However, despite reports showing that loss of DCs induces transient monocytosis, the monocyte population that emerges and the potential impact of monocytes on studies of DC function have not been investigated. We found that depletion of CD11c+ cells from CD11c.DTR mice induced the expansion of a variant CD64+ Ly6C+ monocyte population in the spleen and blood that was distinct from conventional monocytes. Expansion of CD64+ Ly6C+ monocytes was independent of mobilization from the BM via CCR2 but required the cytokine, G-CSF. Indeed, this population was also expanded upon exposure to exogenous G-CSF in the absence of DC depletion. CD64+ Ly6C+ monocytes were characterized by upregulation of innate signaling apparatus despite the absence of inflammation, and an increased capacity to produce TNF-α following LPS stimulation. Thus, depletion of CD11c+ cells induces expansion of a unique CD64+ Ly6C+ monocyte population poised to synthesize TNF-α. This finding will require consideration in experiments using depletion strategies to test the role of CD11c+ DCs in immunity

Outcomes of Advanced Hodgkin Lymphoma after Umbilical Cord Blood Transplantation: A Eurocord and EBMT Lymphoma and Cellular Therapy & Immunobiology Working Party Study

Allogeneic stem cell transplantation is an alternative for patients with relapsed or refractory Hodgkin lymphoma (HL), but only limited data on unrelated umbilical cord blood transplantation (UCBT) are available. We analyzed 131 adults with HL who underwent UCBT in European Society for Blood and Marrow Transplantation centers from 2003 to 2015. Disease status at UCBT was complete remission (CR) in 59 patients (47%), and almost all patients had received a previous autologous stem cell transplantation. The 4-year progression-free survival (PFS) and overall survival (OS) were 26% (95% confidence interval [CI], 19% to 34%) and 46% (95% CI, 37% to 55%), respectively. Relapse incidence was 44% (95% CI, 36% to 54%), and nonrelapse mortality (NRM) was 31% (95% CI, 23% to 40%) at 4 years. In multivariate analysis refractory/relapsed disease status at UCBT was associated with increased relapse incidence (hazard ratio [HR], 3.14 [95% CI, 1.41 to 7.00], P = .005) and NRM (HR, 3.61 [95% CI, 1.58 to 8.27], P = .002) and lower PFS (HR, 3.45 [95% CI, 1.95 to 6.10], P < .001) and OS (HR, 3.10 [95% CI, 1.60 to 5.99], P = .001). Conditioning regimen with cyclophosphamide + fludarabine + 2 Gy total body irradiation (Cy+Flu+2GyTBI) was associated with decreased risk of NRM (HR, .26 [95% CI, .10 to .64], P = .004). Moreover, Cy+Flu+2GyTBI conditioning regimen was associated with a better OS (HR, .25 [95% CI, .12 to .50], P < .001) and PFS (HR, .51 [95% CI, .27 to .96], P = .04). UCBT is feasible in heavily pretreated patients with HL. The reduced-intensity conditioning regimen with Cy+Flu+2GyTBI is associated with a better OS and NRM. However, outcomes are poor in patients not in CR at UCBT

Impact of prior JAK-inhibitor therapy with ruxolitinib on outcome after allogeneic hematopoietic stem cell transplantation for myelofibrosis: a study of the CMWP of EBMT.

JAK1/2 inhibitor ruxolitinib (RUX) is approved in patients with myelofibrosis but the impact of pretreatment with RUX on outcome after allogeneic hematopoietic stem cell transplantation (HSCT) remains to be determined. We evaluated the impact of RUX on outcome in 551 myelofibrosis patients who received HSCT without (n = 274) or with (n = 277) RUX pretreatment. The overall leukocyte engraftment on day 45 was 92% and significantly higher in RUX responsive patients than those who had no or lost response to RUX (94% vs. 85%, p = 0.05). The 1-year non-relapse mortality was 22% without significant difference between the arms. In a multivariate analysis (MVA) RUX pretreated patients with ongoing spleen response at transplant had a significantly lower risk of relapse (8.1% vs. 19.1%; p = 0.04)] and better 2-year event-free survival (68.9% vs. 53.7%; p = 0.02) in comparison to patients without RUX pretreatment. For overall survival the only significant factors were age > 58 years (p = 0.03) and HLA mismatch donor (p = 0.001). RUX prior to HSCT did not negatively impact outcome after transplantation and patients with ongoing spleen response at time of transplantation had best outcome

Outcome after allogeneic stem cell transplantation with haploidentical versus HLA-matched donors in patients with higher-risk MDS.

peer reviewedAllogeneic hematopoietic stem cell transplantation remains the best curative option for higher-risk myelodysplastic syndrome. The presence of monosomal karyotype and/or complex karyotype abnormalities predicts inferior survival after allo-SCT in MDS patients. Haploidentical allo-SCT has been increasingly used in acute leukemia (AL) and has similar results as using HLA-matched donors, but data on higher-risk MDS is sparse. We compared outcomes in 266 patients with higher-risk MDS after HLA-matched sibling donor (MSD, n = 79), HLA-matched unrelated donor (MUD, n = 139) and HLA haploidentical donor (HID, n = 48) from 2010 to 2019. Median donor age differed between the three groups (p < 0.001). The overall survival was significantly different between the three groups with a better OS observed in the MUD group (p = 0.014). This observation could be explained by a higher progression-free survival with MUD (p = 0.014). The cumulative incidence of grade 2-4 acute GvHD was significantly higher in the HID group (p = 0.051). However, in multivariable analysis, patients transplanted using an HID had comparable mortality to patients transplanted using a MUD (subdistribution hazard ratio [sHR]: 0.58 [0.32-1.07]; p = 0.080) and a MSD ([sHR]: 0.56 [0.28-1.11]; p = 0.094). MUD do not remain a significant positive predictor of survival, suggesting that beyond the donor-recipient HLA matching, the donor age might impact recipient outcome