Characteristics and prognosis of patients with COVID-19 and hematological diseases in Japan: a cross-sectional study.

The Japanese Society of Hematology performed an observational cross-sectional study to clarify the morbidity, prognosis, and prognostic factors in patients with COVID-19 with hematological diseases (HDs) in Japan. The study included patients with HDs who enrolled in our epidemiological survey and had a COVID-19 diagnosis and a verified outcome of up to 2 months. The primary endpoints were characteristics and short-term prognosis of COVID-19 in patients with HDs. A total of 367 patients from 68 institutes were enrolled over 1 year, and the collected data were analyzed. The median follow-up among survivors was 73 days (range, 1-639 days). The 60-day overall survival (OS) rate was 86.6%. In the multivariate analysis, albumin ≤ 3.3 g/dL and a need for oxygen were independently associated with inferior 60-day OS rates (hazard ratio [HR] 4.026, 95% confidence interval (CI) 1.954-8.294 and HR 14.55, 95% CI 3.378-62.64, respectively), whereas 60-day survival was significantly greater in patients with benign rather than malignant disease (HR 0.095, 95% CI 0.012-0.750). Together, these data suggest that intensive treatment may be necessary for patients with COVID-19 with malignant HDs who have low albumin levels and require oxygen at the time of diagnosis.

Rationale and protocol design of a phase II study of first-line osimertinib treatment for patients with poor performance status and EGFR mutation-positive non-small cell lung cancer (OPEN/TORG2040).

BACKGROUND: Cancer chemotherapy indications for patients with poor performance status and advanced lung cancer are limited. Molecular targeted drugs, including epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors, can be used in patients with poor performance status owing to their high efficacy and safety. The third-generation EGFR-tyrosine kinase inhibitor osimertinib has demonstrated effectiveness in the initial treatment of advanced EGFR mutation-positive non-small cell lung cancer in patients with good performance status; however, no evidence exists of the drug's effectiveness in patients with poor performance status in a prospective study. We designed a study that aims to investigate the efficacy and safety of first-line osimertinib treatment in patients with advanced non-small cell lung cancer harboring sensitive EGFR mutations and with poor performance status. METHODS: The OPEN/TORG2040 study is a multicenter, single-arm, phase II trial for patients with unresectable, advanced EGFR mutation-positive non-small cell lung cancer with a poor performance status (≥ 2). Eligible patients will receive osimertinib until disease progression or unacceptable toxicity. The primary endpoint is the objective response rate of the first-line osimertinib treatment. Considering a threshold value of 45%, expected value of 70% for objective response rate, one-sided significance level of 5%, statistical power of 80%, and ineligible patients, the sample size was set to 30. The secondary endpoints are disease control rate, performance status improvement rate, and safety and patient-reported outcomes using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core Quality of Life Questionnaire and Lung Cancer 13. Time to treatment failure, progression-free survival, and overall survival will also be assessed. DISCUSSION: Our study can determine the clinical benefits of osimertinib treatment in patients with poor performance status, since the clinical outcomes of patients with EGFR mutation-positive non-small cell lung cancer with poor performance status treated with this drug as a first-line treatment have not been sufficiently evaluated. TRIAL REGISTRATION: Japan Registry of Clinical Trials: jRCTs041200100 (registration date: February 12, 2021).

Clinical characteristics of Japanese patients with polycythemia vera: results of the JSH-MPN-R18 study.

The presence of a JAK2 V617F or JAK2 exon 12 mutation is one of the three major criteria listed for the diagnosis of polycythemia vera (PV) in the 2017 World Health Organization Classification. However, a nationwide study has not yet been conducted in Japan since the discovery of JAK2 mutations. Therefore, the Japanese Society of Hematology (JSH) retrospectively analyzed the clinical characteristics of 596 Japanese patients with PV diagnosed between April 2005 and March 2018. Among the 473 patients with complete data on JAK2 mutations available, 446 (94.3%) and 10 (2.1%) were positive for the JAK2 V617F and JAK2 exon 12 mutations, respectively. During a median follow-up of 46 months (range: 0-179 months), 47 (7.9%) deaths occurred. The major causes of death were secondary malignancies (23.4%), acute leukemia (12.8%), non-leukemic progressive disease (10.6%) and thrombotic (6.4%) and hemorrhagic complications (6.4%). Thrombotic and hemorrhagic events occurred during the clinical course in 4.0% (n = 24) and 3.5% (n = 21) of patients, respectively. These results show that the international PV prognostic score (age, venous thrombosis and leukocytosis) is applicable to Japanese patients with PV.

A use-case analysis of Clinical Data Interchange Standards Consortium/Study Data Tabulation Model in academia in an investigator-initiated clinical trial.

Submitting data compliant with the Clinical Data Interchange Standards Consortium (CDISC) standards is mandatory for new drug applications (NDAs). The standards set by CDISC are widely adopted in the pharmaceutical business world. Introduction of CDISC standards in academia can be necessary to reduce labor, resolve the shortage of data managers in academia, and gain new knowledge through standardized data accumulation. However, the introduction of CDISC standards has not progressed in communities within the academia that do not apply for NDAs. Therefore, herein, we created study data tabulation model (SDTM)-compliant datasets within the academia, without outsourcing, to reduce costs associated with investigator-initiated clinical trials. First, we input data from paper case report forms (CRFs) into an electronic data capture system with minimal function for paper CRFs, "Ptosh," which is compatible with SDTM. Then, we developed a generic program to convert data exported from Ptosh into fully SDTM-compliant datasets. The consistency was then verified with an SDTM validator, Pinnacle21 Community V3.0.1 (P21C). This resulted in generation of SDTM datasets, resolving all "Rejects" in P21C, thereby achieving the required quality level. Although Ptosh directly exports data in SDTM format, manual mapping of items on CRFs to SDTM variables prepared in Ptosh is necessary. SDTM mapping requires extensive knowledge and skills, and it was assumed that mapping is challenging for the staff without in-depth knowledge of CDISC standards and datasets. Therefore, for CDISC dissemination in academia, it is crucial to secure the staff, time, and funding to acquire the knowledge.

Use of Clinical Data Interchange Standards Consortium (CDISC) Standards for Real-world Data: Expert Perspectives From a Qualitative Delphi Survey.

BACKGROUND: Real-world data (RWD) and real-world evidence (RWE) are playing increasingly important roles in clinical research and health care decision-making. To leverage RWD and generate reliable RWE, data should be well defined and structured in a way that is semantically interoperable and consistent across stakeholders. The adoption of data standards is one of the cornerstones supporting high-quality evidence for the development of clinical medicine and therapeutics. Clinical Data Interchange Standards Consortium (CDISC) data standards are mature, globally recognized, and heavily used by the pharmaceutical industry for regulatory submissions. The CDISC RWD Connect Initiative aims to better understand the barriers to implementing CDISC standards for RWD and to identify the tools and guidance needed to more easily implement them. OBJECTIVE: The aim of this study is to understand the barriers to implementing CDISC standards for RWD and to identify the tools and guidance that may be needed to implement CDISC standards more easily for this purpose. METHODS: We conducted a qualitative Delphi survey involving an expert advisory board with multiple key stakeholders, with 3 rounds of input and review. RESULTS: Overall, 66 experts participated in round 1, 56 in round 2, and 49 in round 3 of the Delphi survey. Their inputs were collected and analyzed, culminating in group statements. It was widely agreed that the standardization of RWD is highly necessary, and the primary focus should be on its ability to improve data sharing and the quality of RWE. The priorities for RWD standardization included electronic health records, such as data shared using Health Level 7 Fast Health care Interoperability Resources (FHIR), and the data stemming from observational studies. With different standardization efforts already underway in these areas, a gap analysis should be performed to identify the areas where synergies and efficiencies are possible and then collaborate with stakeholders to create or extend existing mappings between CDISC and other standards, controlled terminologies, and models to represent data originating across different sources. CONCLUSIONS: There are many ongoing data standardization efforts around human health data-related activities, each with different definitions, levels of granularity, and purpose. Among these, CDISC has been successful in standardizing clinical trial-based data for regulation worldwide. However, the complexity of the CDISC standards and the fact that they were developed for different purposes, combined with the lack of awareness and incentives to use a new standard and insufficient training and implementation support, are significant barriers to setting up the use of CDISC standards for RWD. The collection and dissemination of use cases, development of tools and support systems for the RWD community, and collaboration with other standards development organizations are potential steps forward. Using CDISC will help link clinical trial data and RWD and promote innovation in health data science.

Clinical characteristics, prognostic factors, and outcomes of patients with essential thrombocythemia in Japan: the JSH-MPN-R18 study.

We conducted a large-scale, nationwide retrospective study of Japanese patients who were diagnosed with essential thrombocythemia based on the diagnostic criteria in the World Health Organization classification. We investigated clinical characteristics, survival rates, and the incidence of thrombohemorrhagic events as well as risk factors for these events. A total of 1152 patients were analyzed in the present study. Median age at diagnosis was 65 years, the median platelet count was 832 × 109/L, and the positive mutation rates of JAK2V617F, CALR, and MPL were 62.8, 25.1, and 4.1%, respectively. Compared with European and American patients, Japanese patients were more likely to have cardiovascular risk factors and less likely to have systemic symptoms including palpable splenomegaly. Thrombocytosis was identified as a risk factor for hemorrhagic events and prognosis, but not for thrombotic events. The prognostic factors and risk classifications reported in Europe and the United States were generally applicable to Japanese patients. Regarding transformations, secondary myelofibrosis progressed in a time-dependent manner, but progression to acute leukemia was low in "true" ET patients. Skin cancers were less common and gastrointestinal cancers more common as secondary malignancies in Japanese patients, suggesting ethnic differences.

Phase II Clinical Trial of Combination Therapy with Favipiravir and Methylprednisolone for COVID-19 with Non-Critical Respiratory Failure.

INTRODUCTION: The administration of systemic corticosteroids is a key strategy for improving COVID-19 outcomes. However, evidence is lacking on combination therapies of antiviral agents and systemic corticosteroids. The objective of this study was to investigate the efficacy and safety of the combination therapy of favipiravir and methylprednisolone in preventing respiratory failure progression in patients with COVID-19 and non-critical respiratory failure. METHODS: We conducted a multicenter, open-label, single-arm phase II study. The patients received favipiravir 3600 mg on the first day, followed by 1600 mg for a total of 10-14 days. Methylprednisolone was administered intravenously at 1 mg/ideal body weight (IBW)/day from days 1 to 5, followed by 0.5 mg/IBW/day from days 6 to 10 if clinically indicated. The primary endpoint was the proportion of patients requiring mechanical ventilation (MV) (including noninvasive positive pressure ventilation) or those who met the criteria for tracheal intubation within 14 days of the study treatment initiation (MVCTI-14). RESULTS: Sixty-nine patients were enrolled and underwent the study treatment. Of them, the MVCTI-14 proportion was 29.2% (90% confidence interval 20.1-39.9, p = 0.200). The proportion of patients who required MV or who died within 30 days was 26.2%, and 30-day mortality was 4.9%. The most significant risk factor for MVCTI-14 was a smoking history (odds ratio 4.1, 95% confidence interval 1.2-14.2). The most common grade 3-4 treatment-related adverse event was hyperglycemia, which was observed in 21.7%. CONCLUSION: The MVCTI-14 proportion did not reach a favorable level in the clinical trial setting with the threshold of 35%. However, the proportion of MV or death within 30 days was 26.6%, which might be close to the findings (28.1%) of the RECOVERY trial, which showed the efficacy of dexamethasone for patients with COVID-19 and non-critical respiratory failure. Further evaluation of this combination therapy is needed. CLINICAL TRIAL REGISTRATION: Japan Registry of Clinical Trials (jRCT) identifier jRCTs041200025.

A survey of blood transfusion errors in Aichi Prefecture in Japan: Identifying major lapses threatening the safety of transfusion recipients.

BACKGROUND: Despite recent progress in blood systems, transfusion errors can occur at any time from the moment of collection through to the transfusion of blood and blood products. This study investigated the actual statuses of blood transfusion errors at institutions of all sizes in Aichi prefecture. MATERIALS AND METHODS: We investigated 104 institutions that perform 98 % of the blood transfusions in Aichi prefecture, and investigated the errors (incidents/accidents) that occurred at these facilities over 6 months (April to September, 2017). Incident/accident data were collected from responses to questionnaires sent to each institution; these were classified according to the categories and risk levels. RESULTS: Ninety-seven of the 104 institutions (93.3 %) responded to the questionnaire; a total of 688 incidents/accidents were reported. Most (682 cases; 99.2 %), were classified as risk level 2; however, 6 were level 3 and over, which included problems with autologous transfusion and inventory control. Approximately one-half of the incidents/accidents (394 cases; 57.3 %), were related to verification and the actual administration of blood products at the bedside; more than half of these incidents/accidents occurred at large-volume institutions. Meanwhile, a high frequency of incidents/accidents related to transfusion examination and labeling of blood products was observed at small- or medium-sized institutions. The reasons for most of these errors were simple mistakes and carelessness by the medical staff. CONCLUSIONS: Our results emphasize the importance of education, operational training, and compliance instruction for all members of the medical staff despite advances in electronic devices meant to streamline transfusion procedures.

Reporting quality of randomized controlled trials in patients with HIV on antiretroviral therapy: a systematic review.

BACKGROUND: To allow for correct evaluation of clinical trial results, readers require comprehensive, clear, and highly transparent information on the methodology used and the results obtained. This study aimed to evaluate the quality of reporting in articles on randomized controlled trials (RCTs) of antiretroviral therapy (ART) in the field of HIV/AIDS. METHODS: We searched for original articles on RCTs of ART developed in the field of HIV/AIDS in PubMed database by 5 April 2016. Searched articles were divided into three groups based on the revision year in which the Consolidated Standards of Reporting Trials (CONSORT) guidelines were published: Period 1 (1996-2001); Period 2 (2002-2010); and Period 3 (2011-2016). We evaluated the articles using the reporting rates of the 37 items in the CONSORT 2010 checklist, five items in the protocol deviation, and the three items in the ethics. RESULTS: Fifty-two articles were extracted and included in this study. Many of the reporting rates calculated using the CONSORT 2010 checklist showed a significantly increasing trend over the successive periods (65% in Period 1, 67% in Period 2, 79% in Period 3; p < 0.0001). The items with reporting rates < 50% were "the presence or absence of a protocol change and the reason for such a change," "randomization and blinding," and "where the full trial protocol can be accessed." Reporting rates of deviations were as low as < 30%, while the reporting rates for patient compliance were the highest (>80% in Period 3) among the five items. The reporting rates for obtaining informed consent and approval by the ethics committee or institutional review board were high (>88%), regardless of the time period assessed. CONCLUSION: In terms of representative RCT articles in the field of HIV/AIDS, the reporting rate of the items defined by CONSORT was approximately 70%, improving over the successive CONSORT statement revision periods.

CDR3ß sequence motifs regulate autoreactivity of human invariant NKT cell receptors.

Invariant natural killer T (iNKT) cells are a subset of T lymphocytes that recognize lipid ligands presented by monomorphic CD1d. Human iNKT T cell receptor (TCR) is largely composed of invariant Vα24 (Vα24i) TCRα chain and semi-variant Vß11 TCRß chain, where complementarity-determining region (CDR)3ß is the sole variable region. One of the characteristic features of iNKT cells is that they retain autoreactivity even after the thymic selection. However, the molecular features of human iNKT TCR CDR3ß sequences that regulate autoreactivity remain unknown. Since the numbers of iNKT cells with detectable autoreactivity in peripheral blood is limited, we introduced the Vα24i gene into peripheral T cells and generated a de novo human iNKT TCR repertoire. By stimulating the transfected T cells with artificial antigen presenting cells (aAPCs) presenting self-ligands, we enriched strongly autoreactive iNKT TCRs and isolated a large panel of human iNKT TCRs with a broad range autoreactivity. From this panel of unique iNKT TCRs, we deciphered three CDR3ß sequence motifs frequently encoded by strongly-autoreactive iNKT TCRs: a VD region with 2 or more acidic amino acids, usage of the Jß2-5 allele, and a CDR3ß region of 13 amino acids in length. iNKT TCRs encoding 2 or 3 sequence motifs also exhibit higher autoreactivity than those encoding 0 or 1 motifs. These data facilitate our understanding of the molecular basis for human iNKT cell autoreactivity involved in immune responses associated with human disease.

Post-Progression Survival after EGFR-TKI for Advanced Non-Small Cell Lung Cancer Harboring EGFR Mutations.

BACKGROUND: Non-small cell lung cancer (NSCLC) patients that harbor epidermal growth factor receptor (EGFR) mutations benefit from receiving an EGFR-tyrosine kinase inhibitor (TKI); however, post-progression survival (PPS) after EGFR-TKI treatment has not been sufficiently studied. METHODS: We retrospectively reviewed the clinical data from stage IV or recurrent NSCLC patients who harbored EGFR mutations and who received EGFR-TKI as their first-line treatment in our institute between 2009 and 2011. RESULTS: In total, 36 patients received EGFR-TKI treatment as their first-line therapy. Of those 36 patients, 30 experienced recurrence and were enrolled in this study. The median progression-free survival (PFS) of these patients was 8.2 months. Twelve patients received EGFR-TKI treatment beyond the diagnosis of progressive disease (PD), and 8 received second-line therapy. The PPS after EGFR-TKI treatment was 9.1 months, and survival after the termination of EGFR-TKI treatment in those patients treated with second-line chemotherapy was 13.9 months. The site of relapse was investigated and PFS in EGFR-TKI-treated patients with relapse in the brain (11.6 months) showed a trend toward a longer PFS compared with patients with relapse at other sites (8.2 months). The median PPS after EGFR-TKI treatment also showed the same trend in each group (12.9 and 9.2 months, respectively). CONCLUSIONS: The PPS after EGFR-TKI treatment failure was 9.1 months, while the survival of patients who underwent second-line chemotherapy after the termination of EGFR-TKI treatment was 13.9 months, comparable with the overall survival of EGFR mutation-negative patients, as previously reported. The prognosis of these NSCLC patients with EGFR mutations varied according to the sites of recurrence after first-line EGFR-TKI treatment. Of particular note was the prognosis of patients with brain metastases, which tended to be better than that of patients with metastases to other sites.

In vivo imaging of Treg cells providing immune privilege to the haematopoietic stem-cell niche.

Stem cells reside in a specialized regulatory microenvironment or niche, where they receive appropriate support for maintaining self-renewal and multi-lineage differentiation capacity. The niche may also protect stem cells from environmental insults including cytotoxic chemotherapy and perhaps pathogenic immunity. The testis, hair follicle and placenta are all sites of residence for stem cells and are immune-suppressive environments, called immune-privileged sites, where multiple mechanisms cooperate to prevent immune attack, even enabling prolonged survival of foreign allografts without immunosuppression. We sought to determine if somatic stem-cell niches more broadly are immune-privileged sites by examining the haematopoietic stem/progenitor cell (HSPC) niche in the bone marrow, a site where immune reactivity exists. We observed persistence of HSPCs from allogeneic donor mice (allo-HSPCs) in non-irradiated recipient mice for 30 days without immunosuppression with the same survival frequency compared to syngeneic HSPCs. These HSPCs were lost after the depletion of FoxP3 regulatory T (T(reg)) cells. High-resolution in vivo imaging over time demonstrated marked co-localization of HSPCs with T(reg) cells that accumulated on the endosteal surface in the calvarial and trabecular bone marrow. T(reg) cells seem to participate in creating a localized zone where HSPCs reside and where T(reg) cells are necessary for allo-HSPC persistence. In addition to processes supporting stem-cell function, the niche will provide a relative sanctuary from immune attack.

The LRF transcription factor regulates mature B cell development and the germinal center response in mice.

B cells play a central role in immune system function. Deregulation of normal B cell maturation can lead to the development of autoimmune syndromes as well as B cell malignancies. Elucidation of the molecular features of normal B cell development is important for the development of new target therapies for autoimmune diseases and B cell malignancies. Employing B cell-specific conditional knockout mice, we have demonstrated here that the transcription factor leukemia/lymphoma-related factor (LRF) forms an obligate dimer in B cells and regulates mature B cell lineage fate and humoral immune responses via distinctive mechanisms. Moreover, LRF inactivation in transformed B cells attenuated their growth rate. These studies identify what we believe to be a new key factor for mature B cell development and provide a rationale for targeting LRF dimers for the treatment of autoimmune diseases and B cell malignancies.

Generation of transgenic mice on an NOD/SCID background using the conventional microinjection technique.

Humanized mice, which refers to immunodeficient mice repopulated with the human immune system, are powerful tools for study in the field of immunology. It has been difficult, however, to generate these transgenic (Tg) mice directly from such strains as the NOD/SCID mouse. In this study, we describe a method developed by us for the generation of Tg mice on an NOD/SCID background. First, we obtained fertilized eggs efficiently by means of in vitro fertilization (IVF); then, we attempted to generate CAG-EGFP Tg mice on an NOD/SCID background, finding that delayed timing of the microinjection after the IVF improved the time to development of the two-cell-stage embryos and the obtainment of newborns. We successfully generated Tg mice and confirmed the germ-line transmission in the offspring. In conclusion, we established a novel system for directly generating transgenic mice on an NOD/SCID background. This novel system is expected to allow improved efficiency of the generation of humanized mice.

Notch2 signaling is required for proper mast cell distribution and mucosal immunity in the intestine.

Notch receptor-mediated signaling is involved in the developmental process and functional modulation of lymphocytes, as well as in mast cell differentiation. Here, we investigated whether Notch signaling is required for antipathogen host defense regulated by mast cells. Mast cells were rarely found in the small intestine of wild-type C57BL/6 mice but accumulated abnormally in the lamina propria of the small-intestinal mucosa of the Notch2-conditional knockout mice in naive status. When transplanted into mast cell-deficient W(sh)/W(sh) mice, Notch2-null bone marrow-derived mast cells were rarely found within the epithelial layer but abnormally localized to the lamina propria, whereas control bone marrow-derived mast cells were mainly found within the epithelial layer. After the infection of Notch2 knockout and control mice with L3 larvae of Strongyloides venezuelensis, the abundant number of mast cells was rapidly mobilized to the epithelial layer in the control mice. In contrast, mast cells were massively accumulated in the lamina propria of the small intestinal mucosa in Notch2-conditional knockout mice, accompanied by impaired eradication of Strongyloides venezuelensis. These findings indicate that cell-autonomous Notch2 signaling in mast cells is required for proper localization of intestinal mast cells and further imply a critical role of Notch signaling in the host-pathogen interface in the small intestine.

Invariant NKT cells are required for antitumor responses induced by host-versus-graft responses.

Based on clinical observations, we have previously shown in a murine model that recipient leukocyte infusion (RLI) induces a host-versus-graft reaction in mixed bone marrow chimeras and that rejection of donor cells leads to a specific antitumor response against recipient malignancies. This response is dependent on T cells and IFN-gamma. We investigated the role of NKT cells (NKTs) in this phenomenon. Depletion of recipient NK1.1(+) cells led to loss of an anti-tumor effect induced by RLI in mixed bone marrow chimeras. In recipients specifically lacking host invariant NKT cells (iNKTs), RLI did not induce an antitumor effect, indicating a critical role for recipient iNKTs. Conversely, specific activation of iNKTs enhanced the anti-tumor effect induced by RLI. Following RLI, recipient iNKTs, NK cells, dendritic cells (DCs), and CD8 T cells were activated. CD8 T cells were the major producers of IFN-gamma. Lack of recipient iNKTs resulted in failure of activation of NK cells and DCs by RLI. Our studies demonstrate a central role for iNKTs in promoting RLI-induced anti-tumor effects and suggest that this pathway involved promotion of the activation of recipient NK cells and DCs.

Persistence of donor-derived protein in host myeloid cells after induced rejection of engrafted allogeneic bone marrow cells.

OBJECTIVE: In recipients of allogeneic hematopoietic stem cell transplantation to treat hematologic malignancies, we have unexpectedly observed anti-tumor effects in association with donor cell rejection in both mice and humans. Host-type CD8 T cells were shown to be required for these anti-tumor effects in the murine model. Because sustained host CD8 T-cell activation was observed in the murine bone marrow following the disappearance of donor chimerism in the peripheral blood, we hypothesized that donor antigen presentation in the bone marrow might be prolonged. MATERIALS AND METHODS: To assess this hypothesis, we established mixed chimerism with green fluorescent protein (GFP)-positive allogeneic bone marrow cells, induced rejection of the donor cells by giving recipient leukocyte infusions, and utilized in vivo microscopy to follow GFP-positive cells. RESULTS: After peripheral donor leukocytes disappeared, GFP persisted within host myeloid cells surrounding the blood vessels in the bone marrow, suggesting that the host myeloid cells captured donor-derived GFP protein. CONCLUSIONS: Because the host-vs-graft reaction promotes induction of anti-tumor responses in this model, this retention of donor-derived protein may play a role in the efficacy of recipient leukocyte infusions as an anti-tumor therapy.

Clinical relevance of recipient leukocyte infusion as antitumor therapy following nonmyeloablative allogeneic hematopoietic cell transplantation.

OBJECTIVE: Graft-versus-leukemia effects of donor lymphocytes have been considered to be central to the therapeutic benefit of nonmyeloablative allogeneic hematopoietic cell transplantation (HCT) for malignant diseases. Surprisingly, some patients who reject donor grafts following nonmyeloablative HCT have sustained remissions of advanced, chemorefractory hematologic malignancies. In murine mixed chimeras prepared with nonmyeloablative conditioning, we previously showed that recipient leukocyte infusions (RLIs) induce loss of donor chimerism and mediate antitumor responses against host-type tumors. We assessed the clinical relevance of our mouse model. METHODS: Mixed chimeric mice were generated by a nonmyeloablative protocol and some of them received host-derived tumor cells and/or RLIs or donor lymphocyte infusion (DLI). We examined chimerism, graft-versus-host disease (GVHD), and tumor survival. RESULTS: RLI is still effective when the leukocytes are obtained from tumor-bearing mice. Established mixed chimerism is required prior to the induced rejection to achieve maximum antitumor effects. The antitumor effects of RLI are not dependent on a specific donor strain or conditioning protocol. In contrast to DLI, RLI leads to donor cell rejection without the risk of GVHD. CONCLUSION: Together, these data reinforce the clinical potential of RLI therapy as a new HCT strategy that does not carry the risk of GVHD.

Mechanisms of the antitumor responses and host-versus-graft reactions induced by recipient leukocyte infusions in mixed chimeras prepared with nonmyeloablative conditioning: a critical role for recipient CD4+ T cells and recipient leukocyte infusion-derived IFN-gamma-producing CD8+ T cells.

Surprisingly, antitumor responses can occur in patients who reject donor grafts following nonmyeloablative hemopoietic cell transplantation. In murine mixed chimeras prepared with nonmyeloablative conditioning, we previously showed that recipient leukocyte infusions (RLI) induced loss of donor chimerism, IFN-gamma production, and antitumor responses against host-type tumors. However, the mechanisms behind this phenomenon remain to be determined. We now demonstrate that the effects of RLI are mediated by distinct and complex mechanisms. Donor marrow rejection is induced by RLI-derived alloactivated T cells, which activate non-RLI-derived, recipient IFN-gamma-producing cells. RLI-derived CD8 T cells induce the production of IFN-gamma by both RLI and non-RLI-derived recipient cells. The antitumor responses of RLI involve mainly RLI-derived IFN-gamma-producing CD8 T cells and recipient-derived CD4 T cells and do not involve donor T cells. The pathways of donor marrow and tumor rejection lead to the development of tumor-specific cell-mediated cytotoxic responses that are not due to bystander killing by alloreactive T cells.