Immune response to anti-SARS-CoV-2 prime-vaccination in patients with cancer: a systematic review and meta-analysis.

PURPOSE: This systematic review and meta-analysis aimed to evaluate the immune response to anti-SARS-CoV-2 prime-vaccination in patients with cancer. METHODS: We performed a systematic literature search using PubMed, Embase, and Cochrane Library until 28/09/2021, and conference proceedings from ASCO and ESMO 2021 annual meetings. We screened for observational or interventional studies including subjects ≥ 16 years old with cancer diagnosis who were vaccinated against SARS-CoV-2. Prime-vaccination was defined as one dose of Ad26.COV2-S vaccine or two doses of BNT162b2, mRNA-1273, ChAdOx1-S or inactivated SARS-CoV-2 vaccine. The outcomes were humoral and adaptive immune responses (proportion of subjects with positive titers of antibody anti-SARS-CoV-2 spike protein and anti-SARS-CoV-2 cellular responses, respectively). RESULTS: We included 89 records reporting data from 30,183 subjects. The overall seropositive rate within the first month after complete anti-SARS-CoV-2 prime-vaccination was 80% [95% confidence interval (CI), 72-86%], 60% (95%CI, 53-67%) in patients with hematological malignancies (HM) versus 94% (95%CI, 88-97%) in patients with solid malignancies (SM). The diagnosis of HM was significantly associated with a lower seropositive rate on multivariate meta-regression (odds ratio 0.35, 95% CI 0.18-0.69, HM versus both, p = 0.002). The overall humoral response was 49% (95% CI, 42-56%) after incomplete prime-vaccination and 79% (95% CI, 70-86%) at 2 months after complete prime-vaccination. These responses were also lower in patients with HM at these time points. The overall cellular response rate at any time after vaccination was 61% (95% CI, 44-76%). CONCLUSION: This meta-analysis provides compelling evidence of humoral and adaptive immune responses against SARS-CoV-2 in patients with cancer, which last for at least 2 months following complete prime-vaccination.

New Perspectives in Treating Acute Myeloid Leukemia: Driving towards a Patient-Tailored Strategy.

For decades, intensive chemotherapy (IC) has been considered the best therapeutic option for treating acute myeloid leukemia (AML), with no curative option available for patients who are not eligible for IC or who have had failed IC. Over the last few years, several new drugs have enriched the therapeutic arsenal of AML treatment for both fit and unfit patients, raising new opportunities but also new challenges. These include the already approved venetoclax, the IDH1/2 inhibitors enasidenib and ivosidenib, gemtuzumab ozogamicin, the liposomal daunorubicin/cytarabine formulation CPX-351, and oral azacitidine. Venetoclax, an anti BCL2-inhibitor, in combination with hypomethylating agents (HMAs), has markedly improved the management of unfit and elderly patients from the perspective of improved quality of life and better survival. Venetoclax is currently under investigation in combination with other old and new drugs in early phase trials. Recently developed drugs with different mechanisms of action and new technologies that have already been investigated in other settings (BiTE and CAR-T cells) are currently being explored in AML, and ongoing trials should determine promising agents, more synergic combinations, and better treatment strategies. Access to new drugs and inclusion in clinical trials should be strongly encouraged to provide scientific evidence and to define the future standard of treatment in AML.

Factors associated with SARS-CoV-2 infection and outcome in patients with solid tumors or hematological malignancies: a single-center study.

BACKGROUND: Immunocompromised cancer patients are presumed to be at high risk of developing COVID-19 infection. Predisposing factors to contracting COVID-19 and to severe outcomes have been described in registries but were not compared between solid tumors and hematological malignancies. METHOD: This retrospective single oncologic center study included adults with solid tumors or hematological malignancies referred to testing by naso-pharyngeal swab for a SARS-CoV-2 RT-PCR from March 10 to May 18, 2020. RESULTS: A total of 212 patients were included in the study. Forty-five (21%) were tested positive with SARS-CoV-2. The univariate analysis with positive SARS-CoV-2 PCR as a dependent variable reveals significant odds ratios (ORs) for age-with a mean of 62.5 years-(OR: 1.05, 95% CI: 1.02-1.08), performance status ≥2 (OR: 2.38, 95% CI: 1.22-4.70), inpatient status (OR: 2.36, 95%CI: 1.11-4.91), and hematological malignancies (OR: 2.48, 95% CI: 1.23-4.96). In contrast, OR for solid tumors reveals a negative association (OR: 0.40, 95% CI: 0.20-0.81). When integrating severe outcome (ICU admission or COVID-19-related death) as a dependent variable, the univariate logistic regression model shows significant ORs for pre-existing lymphopenia (OR: 4.0, 95% CI: 1.17-15.04), hematological malignancies (OR: 3.73, 95% CI: 1.09-13.80), and a negative association for solid tumors (OR: 0.27; 95% CI: 0.07-0.92). CONCLUSION: In patients referred for SARS-CoV-2 testing, hematological malignancies were associated with a higher risk of COVID-19 infection and severe outcomes. Other factors were age and inpatient status.

Allogeneic transplantation after PD-1 blockade for classic Hodgkin lymphoma.

Anti-PD-1 monoclonal antibodies yield high response rates in patients with relapsed/refractory classic Hodgkin lymphoma (cHL), but most patients will eventually progress. Allogeneic hematopoietic cell transplantation (alloHCT) after PD-1 blockade may be associated with increased toxicity, raising challenging questions about the role, timing, and optimal method of transplantation in this setting. To address these questions, we assembled a retrospective cohort of 209 cHL patients who underwent alloHCT after PD-1 blockade. With a median follow-up among survivors of 24 months, the 2-year cumulative incidences (CIs) of non-relapse mortality and relapse were 14 and 18%, respectively; the 2-year graft-versus-host disease (GVHD) and relapse-free survival (GRFS), progression-free survival (PFS), and overall survival were 47%, 69%, and 82%, respectively. The 180-day CI of grade 3-4 acute GVHD was 15%, while the 2-year CI of chronic GVHD was 34%. In multivariable analyses, a longer interval from PD-1 to alloHCT was associated with less frequent severe acute GVHD, while additional treatment between PD-1 and alloHCT was associated with a higher risk of relapse. Notably, post-transplant cyclophosphamide (PTCy)-based GVHD prophylaxis was associated with significant improvements in PFS and GRFS. While awaiting prospective clinical trials, PTCy-based GVHD prophylaxis may be considered the optimal transplantation strategy for this patient population.

Chimeric antigen receptor T-cell lymphoma immunotherapy: the next questions.

PURPOSE OF REVIEW: Chimeric antigen receptor (CAR) T-cell therapy is an innovative form of adoptive cellular immunotherapy targeting CD19 in its most advanced form. Up to 30% of infused patients achieve long-term survival, meaning that 70% of patients still fail to respond or relapse after therapy. This review will address the unresolved issues relating to responders' characterization, relapse prediction, and prevention, CAR T-cell construct optimization, rational combination with other therapies and treatment toxicity, focusing on the management of relapsed/refractory lymphoma patients. RECENT FINDINGS: Many new antigenic targets are currently investigated and raise the hope of broader successes. However, literature data report that treatment failure is not only related to CAR T construct and infusion but is also due to hostile tumor microenvironment and poor interaction with the host effector cells. Further research should not only target CAR T structure, toxicity and associated therapies, but also tumor-related and host-related microenvironment interactions that lead to treatment failure in relapsed/refractory lymphoma patients. SUMMARY: Poor persistence of CAR T and loss of CD19 antigen are well established mechanisms of relapse in Acute Lymphoblastic Leukemia (ALL). A fourth generation of CAR T construct is currently investigated to overcome this issue. In non-Hodgkin lymphoma, mechanisms of treatment failure remain poorly understood but tumor and host microenvironment are undoubtedly involved and should be further investigated. A deeper understanding of CAR T-cell therapy failure in individuals will help personalize CAR T-cell therapy in the future.

Donor-Derived Myeloid Heme Oxygenase-1 Controls the Development of Graft-Versus-Host Disease.

Graft-versus-host disease (GVHD) remains a major clinical drawback of allogeneic hematopoietic stem cell transplantation (HSCT). Here, we investigated how the stress responsive heme catabolizing enzyme heme oxygenase-1 (HO-1, encoded by HMOX1) regulates GVHD in response to allogeneic hematopoietic stem cell transplantation in mice and humans. We found that deletion of the Hmox1 allele, specifically in the myeloid compartment of mouse donor bone marrow, promotes the development of aggressive GVHD after allogeneic transplantation. The mechanism driving GVHD in mice transplanted with allogeneic bone marrow lacking HO-1 expression in the myeloid compartment involves enhanced T cell alloreactivity. The clinical relevance of these observations was validated in two independent cohorts of HSCT patients. Individuals transplanted with hematopoietic stem cells from donors carrying a long homozygous (GT)n repeat polymorphism (L/L) in the HMOX1 promoter, which is associated with lower HO-1 expression, were at higher risk of developing severe acute GVHD as compared to donors carrying a short (GT)n repeat (S/L or S/S) polymorphism associated with higher HO-1 expression. In this study, we showed the unique importance of donor-derived myeloid HO-1 in the prevention of lethal experimental GVHD and we corroborated this observation by demonstrating the association between human HMOX1 (GT)n microsatellite polymorphisms and the incidence of severe acute GVHD in two independent HSCT patient cohorts. Donor-derived myeloid HO-1 constitutes a potential therapeutic target for HSCT patients and large-scale prospective studies in HSCT patients are necessary to validate the HO-1 L/L genotype as an independent risk factor for developing severe acute GVHD.

Long-term follow-up of 2 patients treated with 90 Y-rituximab radioimmunotherapy for relapse of nodular lymphocyte-predominant Hodgkin lymphoma.

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) is a rare lymphoma (<5% of Hodgkin's lymphomas) predominantly affecting the middle-aged man, with an indolent behavior. Given the rare occurrence of this lymphoma, there are currently no clear guidelines for initial treatment or relapse. In this report, we present the follow-up of 2 patients treated by radioimmunotherapy for first relapse of their NLPHL. Both patients were initially treated with rituximab and relapsed 1 year after the end of their treatment.

The cholinergic anti-inflammatory pathway delays TLR-induced skin allograft rejection in mice: cholinergic pathway modulates alloreactivity.

Activation of innate immunity through Toll-like receptors (TLR) can abrogate transplantation tolerance by revealing hidden T cell alloreactivity. Separately, the cholinergic anti-inflammatory pathway has the capacity to dampen macrophage activation and cytokine release during endotoxemia and ischemia reperfusion injury. However, the relevance of the α7 nicotinic acetylcholine receptor (α7nAChR)-dependent anti-inflammatory pathway in the process of allograft rejection or maintenance of tolerance remains unknown. The aim of our study is to investigate whether the cholinergic pathway could impact T cell alloreactivity and transplant outcome in mice. For this purpose, we performed minor-mismatched skin allografts using donor/recipient combinations genetically deficient for the α7nAChR. Minor-mismatched skin grafts were not rejected unless the mice were housed in an environment with endogenous pathogen exposure or the graft was treated with direct application of imiquimod (a TLR7 ligand). The α7nAChR-deficient recipient mice showed accelerated rejection compared to wild type recipient mice under these conditions of TLR activation. The accelerated rejection was associated with enhanced IL-17 and IFN-γ production by alloreactive T cells. An α7nAChR-deficiency in the donor tissue facilitated allograft rejection but not in recipient mice. In addition, adoptive T cell transfer experiments in skin-grafted lymphopenic animals revealed a direct regulatory role for the α7nAChR on T cells. Taken together, our data demonstrate that the cholinergic pathway regulates alloreactivity and transplantation tolerance at multiple levels. One implication suggested by our work is that, in an organ transplant setting, deliberate α7nAChR stimulation of brain dead donors might be a valuable approach for preventing donor tissue inflammation prior to transplant.

IL-17A and IL-2-expanded regulatory T cells cooperate to inhibit Th1-mediated rejection of MHC II disparate skin grafts.

Several evidences suggest that regulatory T cells (Treg) promote Th17 differentiation. Based on this hypothesis, we tested the effect of IL-17A neutralization in a model of skin transplantation in which long-term graft survival depends on a strong in vivo Treg expansion induced by transient exogenous IL-2 administration. As expected, IL-2 supplementation prevented rejection of MHC class II disparate skin allografts but, surprisingly, not in IL-17A-deficient recipients. We attested that IL-17A was not required for IL-2-mediated Treg expansion, intragraft recruitment or suppressive capacities. Instead, IL-17A prevented allograft rejection by inhibiting Th1 alloreactivity independently of Tregs. Indeed, T-bet expression of naive alloreactive CD4+ T cells and the subsequent Th1 immune response was significantly enhanced in IL-17A deficient mice. Our results illustrate for the first time a protective role of IL-17A in CD4+-mediated allograft rejection process.