Exagamglogene Autotemcel for Transfusion-Dependent ß-Thalassemia.

BACKGROUND: Exagamglogene autotemcel (exa-cel) is a nonviral cell therapy designed to reactivate fetal hemoglobin synthesis through ex vivo clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 gene editing of the erythroid-specific enhancer region of BCL11A in autologous CD34+ hematopoietic stem and progenitor cells (HSPCs). METHODS: We conducted an open-label, single-group, phase 3 study of exa-cel in patients 12 to 35 years of age with transfusion-dependent ß-thalassemia and a ß0/ß0, ß0/ß0-like, or non-ß0/ß0-like genotype. CD34+ HSPCs were edited by means of CRISPR-Cas9 with a guide mRNA. Before the exa-cel infusion, patients underwent myeloablative conditioning with pharmacokinetically dose-adjusted busulfan. The primary end point was transfusion independence, defined as a weighted average hemoglobin level of 9 g per deciliter or higher without red-cell transfusion for at least 12 consecutive months. Total and fetal hemoglobin concentrations and safety were also assessed. RESULTS: A total of 52 patients with transfusion-dependent ß-thalassemia received exa-cel and were included in this prespecified interim analysis; the median follow-up was 20.4 months (range, 2.1 to 48.1). Neutrophils and platelets engrafted in each patient. Among the 35 patients with sufficient follow-up data for evaluation, transfusion independence occurred in 32 (91%; 95% confidence interval, 77 to 98; P<0.001 against the null hypothesis of a 50% response). During transfusion independence, the mean total hemoglobin level was 13.1 g per deciliter and the mean fetal hemoglobin level was 11.9 g per deciliter, and fetal hemoglobin had a pancellular distribution (≥94% of red cells). The safety profile of exa-cel was generally consistent with that of myeloablative busulfan conditioning and autologous HSPC transplantation. No deaths or cancers occurred. CONCLUSIONS: Treatment with exa-cel, preceded by myeloablation, resulted in transfusion independence in 91% of patients with transfusion-dependent ß-thalassemia. (Supported by Vertex Pharmaceuticals and CRISPR Therapeutics; CLIMB THAL-111 ClinicalTrials.gov number, NCT03655678.).

Exagamglogene Autotemcel for Severe Sickle Cell Disease.

BACKGROUND: Exagamglogene autotemcel (exa-cel) is a nonviral cell therapy designed to reactivate fetal hemoglobin synthesis by means of ex vivo clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 gene editing of autologous CD34+ hematopoietic stem and progenitor cells (HSPCs) at the erythroid-specific enhancer region of BCL11A. METHODS: We conducted a phase 3, single-group, open-label study of exa-cel in patients 12 to 35 years of age with sickle cell disease who had had at least two severe vaso-occlusive crises in each of the 2 years before screening. CD34+ HSPCs were edited with the use of CRISPR-Cas9. Before the exa-cel infusion, patients underwent myeloablative conditioning with pharmacokinetically dose-adjusted busulfan. The primary end point was freedom from severe vaso-occlusive crises for at least 12 consecutive months. A key secondary end point was freedom from inpatient hospitalization for severe vaso-occlusive crises for at least 12 consecutive months. The safety of exa-cel was also assessed. RESULTS: A total of 44 patients received exa-cel, and the median follow-up was 19.3 months (range, 0.8 to 48.1). Neutrophils and platelets engrafted in each patient. Of the 30 patients who had sufficient follow-up to be evaluated, 29 (97%; 95% confidence interval [CI], 83 to 100) were free from vaso-occlusive crises for at least 12 consecutive months, and all 30 (100%; 95% CI, 88 to 100) were free from hospitalizations for vaso-occlusive crises for at least 12 consecutive months (P<0.001 for both comparisons against the null hypothesis of a 50% response). The safety profile of exa-cel was generally consistent with that of myeloablative busulfan conditioning and autologous HSPC transplantation. No cancers occurred. CONCLUSIONS: Treatment with exa-cel eliminated vaso-occlusive crises in 97% of patients with sickle cell disease for a period of 12 months or more. (CLIMB SCD-121; ClinicalTrials.gov number, NCT03745287.).

Biologic and Clinical Efficacy of LentiGlobin for Sickle Cell Disease.

BACKGROUND: Sickle cell disease is characterized by the painful recurrence of vaso-occlusive events. Gene therapy with the use of LentiGlobin for sickle cell disease (bb1111; lovotibeglogene autotemcel) consists of autologous transplantation of hematopoietic stem and progenitor cells transduced with the BB305 lentiviral vector encoding a modified ß-globin gene, which produces an antisickling hemoglobin, HbAT87Q. METHODS: In this ongoing phase 1-2 study, we optimized the treatment process in the initial 7 patients in Group A and 2 patients in Group B with sickle cell disease. Group C was established for the pivotal evaluation of LentiGlobin for sickle cell disease, and we adopted a more stringent inclusion criterion that required a minimum of four severe vaso-occlusive events in the 24 months before enrollment. In this unprespecified interim analysis, we evaluated the safety and efficacy of LentiGlobin in 35 patients enrolled in Group C. Included in this analysis was the number of severe vaso-occlusive events after LentiGlobin infusion among patients with at least four vaso-occlusive events in the 24 months before enrollment and with at least 6 months of follow-up. RESULTS: As of February 2021, cell collection had been initiated in 43 patients in Group C; 35 received a LentiGlobin infusion, with a median follow-up of 17.3 months (range, 3.7 to 37.6). Engraftment occurred in all 35 patients. The median total hemoglobin level increased from 8.5 g per deciliter at baseline to 11 g or more per deciliter from 6 months through 36 months after infusion. HbAT87Q contributed at least 40% of total hemoglobin and was distributed across a mean (±SD) of 85±8% of red cells. Hemolysis markers were reduced. Among the 25 patients who could be evaluated, all had resolution of severe vaso-occlusive events, as compared with a median of 3.5 events per year (range, 2.0 to 13.5) in the 24 months before enrollment. Three patients had a nonserious adverse event related or possibly related to LentiGlobin that resolved within 1 week after onset. No cases of hematologic cancer were observed during up to 37.6 months of follow-up. CONCLUSIONS: One-time treatment with LentiGlobin resulted in sustained production of HbAT87Q in most red cells, leading to reduced hemolysis and complete resolution of severe vaso-occlusive events. (Funded by Bluebird Bio; HGB-206 ClinicalTrials.gov number, NCT02140554.).

Lack of IFN-γ Receptor Signaling Inhibits Graft-versus-Host Disease by Potentiating Regulatory T Cell Expansion and Conversion.

IFN-γ is a pleiotropic cytokine that plays a controversial role in regulatory T cell (Treg) activity. In this study, we sought to understand how IFN-γ receptor (IFN-γR) signaling affects donor Tregs following allogeneic hematopoietic cell transplant (allo-HCT), a potentially curative therapy for leukemia. We show that IFN-γR signaling inhibits Treg expansion and conversion of conventional T cells (Tcons) to peripheral Tregs in both mice and humans. Mice receiving IFN-γR-deficient allo-HCT showed markedly reduced graft-versus-host disease (GVHD) and graft-versus-leukemia (GVL) effects, a trend associated with increased frequencies of Tregs, compared with recipients of wild-type allo-HCT. In mice receiving Treg-depleted allo-HCT, IFN-γR deficiency-induced peripheral Treg conversion was effective in preventing persistent GVHD while minimally affecting GVL effects. Thus, impairing IFN-γR signaling in Tcons may offer a promising strategy for achieving GVL effects without refractory GVHD. Similarly, in a human PBMC-induced xenogeneic GVHD model, significant inhibition of GVHD and an increase in donor Tregs were observed in mice cotransferred with human CD4 T cells that were deleted of IFN-γR1 by CRISPR/Cas9 technology, providing proof-of-concept support for using IFN-γR-deficient T cells in clinical allo-HCT.

CRISPR-Cas9 Gene Editing for Sickle Cell Disease and ß-Thalassemia.

Transfusion-dependent ß-thalassemia (TDT) and sickle cell disease (SCD) are severe monogenic diseases with severe and potentially life-threatening manifestations. BCL11A is a transcription factor that represses γ-globin expression and fetal hemoglobin in erythroid cells. We performed electroporation of CD34+ hematopoietic stem and progenitor cells obtained from healthy donors, with CRISPR-Cas9 targeting the BCL11A erythroid-specific enhancer. Approximately 80% of the alleles at this locus were modified, with no evidence of off-target editing. After undergoing myeloablation, two patients - one with TDT and the other with SCD - received autologous CD34+ cells edited with CRISPR-Cas9 targeting the same BCL11A enhancer. More than a year later, both patients had high levels of allelic editing in bone marrow and blood, increases in fetal hemoglobin that were distributed pancellularly, transfusion independence, and (in the patient with SCD) elimination of vaso-occlusive episodes. (Funded by CRISPR Therapeutics and Vertex Pharmaceuticals; ClinicalTrials.gov numbers, NCT03655678 for CLIMB THAL-111 and NCT03745287 for CLIMB SCD-121.).

Psychiatric comorbidities in adults with sickle cell disease: A narrative review.

Although descriptions of quality of life and patient reports of mood in sickle cell disease (SCD) have become more common in the literature, less is known about psychiatric illness prevalence, presentation, and treatment, particularly for adults. We provide a narrative review of what is known about common and debilitating psychiatric conditions such as depression, anxiety, and cognitive impairment, specifically for adults with SCD. We discuss the limitations of the current evidence, make provisional recommendations, and identify opportunities for research and improved care.

First report of outcomes in patients with stage IIIb AL amyloidosis treated with Dara-VCD front-line therapy.

Although Dara-VCD (daratumumab-bortezomib-cyclophosphamide-dexamethasone) has revolutionized the treatment of newly diagnosed Amyloid Light chain (AL) amyloidosis, patients with stage IIIb disease were excluded in the pivotal trial. We performed a multicentre retrospective cohort study to investigate the outcomes of 19 consecutive patients treated with Dara-VCD front-line therapy who had stage IIIb AL at diagnosis. More than two thirds presented with New York Heart Association Class III/IV symptoms, and had a median of two organs involved (range, 2-4). The haematologic overall response rate was 100%, with 17/19 patients (89.5%) achieving a very good partial response (VGPR) or better. Haematologic responses were achieved rapidly, as evidenced by 63% of evaluable patients with involved serum free light chains (iFLC) < 2 mg/dl and the difference between involved and uninvolved serum free light chains (dFLC) <1 mg/dl at three months. Among 18 evaluable patients, 10 (56%) achieved a cardiac organ response and six (33%) cardiac VGPR or better. The median time to first cardiac response was 1.9 months (range, 0.4-7.3). At a median follow-up of 12 months for surviving patients, estimated one-year overall survival was 67.5% [95% confidence interval (CI), 43.8-84.7]. The incidence of grade 3 or higher infections was 21%, with no infection-related mortality thus far. In summary, Dara-VCD has a promising efficacy and safety profile in stage IIIb AL, and should be studied in prospective trials.

Targeting the GCK pathway: a novel and selective therapeutic strategy against RAS-mutated multiple myeloma.

In multiple myeloma (MM), frequent mutations of NRAS, KRAS, or BRAF are found in up to 50% of newly diagnosed patients. The majority of the NRAS, KRAS, and BRAF mutations occur in hotspots causing constitutive activation of the corresponding proteins. Thus, targeting RAS mutation in MM will increase therapeutic efficiency and potentially overcome drug resistance. We identified germinal center kinase (GCK) as a novel therapeutic target in MM with RAS mutation. GCK knockdown (KD) in MM cells demonstrated in vitro and in vivo that silencing of GCK induces MM cell growth inhibition, associated with blocked MKK4/7-JNK phosphorylation and impaired degradation of IKZF1/3, BCL-6, and c-MYC. These effects were rescued by overexpression of a short hairpin RNA (shRNA)-resistant GCK, thereby excluding the potential off-target effects of GCK KD. In contrast, overexpression of shRNA-resistant GCK kinase-dead mutant (K45A) inhibited MM cell proliferation and failed to rescue the effects of GCK KD on MM growth inhibition, indicating that GCK kinase activity is critical for regulating MM cell proliferation and survival. Importantly, the higher sensitivity to GCK KD in RASMut cells suggests that targeting GCK is effective in MM, which harbors RAS mutations. In accordance with the effects of GCK KD, the GCK inhibitor TL4-12 dose-dependently downregulated IKZF1 and BCL-6 and led to MM cell proliferation inhibition accompanied by induction of apoptosis. Here, our data identify GCK as a novel target in RASMut MM cells, providing a rationale to treat RAS mutations in MM. Furthermore, GCK inhibitors might represent an alternative therapy to overcome immunomodulatory drug resistance in MM.

Phase 1a/b study of monoclonal antibody CAEL-101 (11-1F4) in patients with AL amyloidosis.

Systemic immunoglobulin light-chain amyloidosis is characterized by pathologic deposition of immunoglobulin light chains as amyloid fibrils in vital organs, leading to organ impairment and eventual death. That the process is reversible was evidenced in an in vivo experimental model in which fibril-reactive chimeric monoclonal antibody (mAb) 11-1F4 directly targeted human light-chain amyloid deposits and affected their removal via a phagocyte-mediated response. To determine the tolerability and potential amyloidolytic effect of this agent (now designated mAb CAEL-101), we conducted a phase 1a/b study involving 27 patients, most of whom had manifestations of organ involvement. This was an open-label study in which phase 1a patients received mAb CAEL-101 as a single intravenous infusion with escalating dose levels from 0.5 mg/m2 to 500 mg/m2 to establish the maximum tolerated dose (MTD). In phase 1b, the antibody was administered as a graded series of 4 weekly infusions. For both phases, there were no drug-related serious adverse events or dose-limiting toxicities among recipients, and the MTD was not reached. The majority of patients had deep hematologic responses but persistent organ disease prior to treatment. Fifteen of 24 patients (63%) who manifested cardiac, renal, hepatic, gastrointestinal, or soft tissue involvement had a therapeutic response to mAb CAEL-101 as evidenced by serum biomarkers or objective imaging modalities with a median time to response of 3 weeks. Infusions of mAb CAEL-101 were well tolerated and, for the majority, resulted in improved organ function, notably for those with cardiac impairment. This trial was registered at www.clinicaltrials.gov as #NCT02245867.

Improved serologic responses to DTaP over Tdap vaccination in adult hematopoietic cell transplant recipients.

BACKGROUND: Hematopoietic cell transplantation (HCT) recipients have reduced antibody titers to tetanus, diphtheria, and pertussis. Tdap is approved for revaccinating adult HCT recipients in the United States, whereas DTaP is not approved in this population. To our knowledge, no studies to date have compared responses to DTaP versus Tdap in adult HCT patients. We conducted a retrospective study comparing responses to DTaP versus Tdap vaccines in otherwise similar adult HCT patients in order to determine if one of these vaccines elicits superior antibody responses. METHODS: We evaluated 43 allogeneic and autologous transplant recipients as a combined cohort and as separate subsets for vaccine specific antibody titers and proportion of strong vaccine responders. Subset analysis focused on the autologous transplant recipients. RESULTS: Higher median antibody titers were found to all vaccine components among DTaP recipients (diphtheria p = .021, pertussis p = .020, tetanus p = .007). DTaP recipients also had more strong responders to diphtheria and pertussis (diphtheria p = .002, pertussis p = .006). Among the autologous HCT recipient subset, there were more strong responders to diphtheria (p = .036). CONCLUSIONS: Our data shows that post-HCT vaccination with DTaP leads to higher antibody titers and more strong responders, which suggests that DTaP is more effective than Tdap in HCT recipients.

Development of T-cell immunity in a liver and hematopoietic stem cell transplant recipient following coronavirus disease 2019 infection.

The outbreak of coronavirus disease 2019 (COVID-19) has disproportionately affected patients with comorbidities, including recipients of solid organ and hematopoietic stem cell transplants (SCT). Upon recovery from COVID-19, the degree of the immunological protection from reinfection remains unclear. Here we describe a 33-year-old patient with erythropoietic protoporphyria (EPP) who had undergone liver transplantation with splenectomy followed by allogeneic SCT in 2013 after an initial failed liver and umbilical cord transplant. The patient developed mild upper respiratory symptoms in the spring of 2020 and was found to have anti-SARS-CoV2 antibodies suggesting past infection. A comprehensive analysis of T cell functionality in peripheral blood from this patient revealed robust in vitro responses against SARS CoV2 antigens Spike (S) 1 and 2, membrane (M) and nucleoprotein (NP), comparable to the reactivity against common antigens from CMV, EBV, Ad and BK viruses, while only low reactivity was seen in healthy donors without documented history of COVID-19. Moreover, the patient displayed a marked recognition of counterpart antigens from related human coronaviruses (hCoVs) 229E, OC43, NL63 and HKU1. Thus, despite lifelong immunosuppression, this survivor of COVID-19 retained a remarkable degree of immunocompetence and showed broad-spectrum T cell memory specific for SARS-CoV2 and related hCoVs including less studied hCoV M and NP antigens. The study highlights the role of cellular immunity after natural COVID-19 infection, suggesting broader use of T cell assays as a tool for risk stratification, measurement of immunocompetence and/or post-infection or post-vaccination protection, and possible T cell-based adoptive immunotherapy strategies in high-risk patients.

Gastrointestinal toxicity of high-dose melphalan in autologous hematopoietic stem cell transplantation: identification of risk factors and a benchmark for experimental therapies.

Gastrointestinal side effects are the dose-limiting toxicity of high-dose melphalan (HDM) in autologous hematopoietic stem-cell transplantation, but there are limited contemporary data on the incidence and severity of gastrointestinal toxicity associated with this regimen. We retrospectively studied 100 consecutive patients who received HDM alone or in combination with other conditioning agents. Patients had a median age of 56 (range 20-73); underlying diseases were myeloma (42%), lymphoma (42%), or amyloidosis (16%) and melphalan dosages were 200 (40%), 140 (59%), or 100 mg/m2 (1%). Ninety-seven percent of patients experienced diarrhea with a range of 1-18 bowel movements per day, 88% developed nausea, and 60% experienced vomiting. Abdominal CT scans rarely altered patient management, but stool studies were useful in identifying a treatable infectious source. Grade ≥ 2 diarrhea was associated with longer duration of diarrhea, longer length of stay, worse hypoalbuminemia, higher use of antibiotics, abdominal imaging, electrolyte repletions, and anti-diarrheal agents. Risk factors for severe diarrhea were female sex, melphalan dose, age > 50, creatinine clearance < 60 ml/min, and having a plasma cell neoplasm as opposed to lymphoma. Female sex was also associated with more severe nausea and vomiting. In summary, diarrhea remains an important toxicity of HDM and novel therapies for chemotherapy-induced diarrhea for patients undergoing stem-cell transplantation are needed. Grade 2 or higher diarrhea is associated with significant clinical consequences and should be used as the primary endpoint in prospective clinical trials.

Extended letermovir administration, beyond day 100, is effective for CMV prophylaxis in patients with graft versus host disease.

BACKGROUND: Cytomegalovirus (CMV) reactivation is associated with significant morbidity and mortality after an allogeneic hematopoietic cell transplant (AHCT), and graft versus host disease (GVHD) increases the risk of CMV reactivation. Letermovir is approved for CMV prophylaxis in CMV-seropositive patients, but has only been studied through day 100 post-transplantation in the registration trial. Its efficacy in preventing CMV in patients with GVHD requiring treatment beyond the day 100 milestone has not been studied. METHODS: We retrospectively analyzed all patients who underwent an AHCT at a single center over a period of 24 months, and identified a cohort of 20 patients who received extended duration of letermovir (beyond 100 days) after the diagnosis of GVHD. The primary end point was the incidence of clinically significant CMV infection, defined as onset of CMV disease or initiation of preemptive therapy with alternative antiviral agents. RESULTS: In this high-risk cohort, only one patient (5%) developed a clinically significant CMV infection, requiring preemptive therapy. No patients developed CMV organ disease. Three additional patients developed CMV viremia of ≥150 IU/mL while on letermovir and after the onset of GVHD, and none required additional treatment. Receipt of post-transplant cyclophosphamide (PTCy) and low CD4 count after the development of GVHD were associated with breakthrough CMV viremia while on extended duration letermovir. CONCLUSIONS: Extended duration letermovir was efficacious in preventing clinically significant CMV infections in patients with GVHD.

Fertility Concerns and Access to Care for Stem Cell Transplantation Candidates with Sickle Cell Disease.

Sickle cell disease (SCD) affects 100,000 Americans and causes significant psychiatric illness and poor quality of life in many domains, including infertility. Hematopoietic cell transplantation (HCT) is the only available cure for SCD, but it can entail chronic toxicities, including psychiatric conditions, such as depression and anxiety, and sterility in both men and women. There is scant literature on fertility or psychiatric outcomes for patients with SCD receiving HCT, and none considering the additive ramifications of the stresses of SCD, transplantation, and infertility. Financial toxicity is a significant concern for all patients undergoing HCT. Treatment for infertility is also very expensive, and access to fertility services is variable in the United States, adding to the medical and quality of life burden for this patient population. Here we review the relevant areas of SCD and infertility, SCD and psychiatric wellness, access to care, and infertility and quality of life. Collectively, these data suggest that the group of patients with SCD who undergo HCT and experience infertility are at particularly high risk for poor quality of life, worsening psychiatric health, and poor access to adequate fertility treatment.

Standardized Semi-structured Psychosocial Evaluation before Hematopoietic Stem Cell Transplantation Predicts Patient Adherence to Post-Transplant Regimen.

In patients undergoing stem cell transplantation (SCT), nonadherence has potential for significant medical impact and potentially life-threatening complications. No study thus far has demonstrated an effective way to predict adherence in SCT recipients. A structured rating scale, the Stanford Integrated Psychosocial Assessment for Transplantation (SIPAT), has been shown to predict psychosocial outcomes and medical morbidity in solid organ transplant recipients. We assessed the SIPAT in SCT recipients. We hypothesized that the SIPAT rating would be associated with nonadherence to the post-SCT regimen. We retrospectively studied SCT recipients who had psychiatric evaluations with the SIPAT before SCT. The primary outcome was nonadherence, defined a priori as at least 1 life-threatening nonadherence event in the first 6 months post-transplant. Association of the SIPAT with outcomes was evaluated by logistic regression, and an optimal cutoff score was determined using a receiver operating characteristic curve. Of 85 patients (mean age 47 years; range, 18 to 74 years), 56 (66%) were male, and 43 (50.5%) received autologous SCT. Eighteen (21%) patients were nonadherent. The SIPAT rating, treated as a continuous variable and controlling for autologous versus allogeneic SCT, was significantly associated with nonadherence (per 1 point; odds ratio [OR], 1.162; P< .0001). Allogeneic SCT also conferred a significantly increased risk of nonadherence (OR, 14.184; P= .005). Multivariate analysis stratifying for allogeneic versus autologous transplantation and controlling for age, sex, and disease confirmed an independent association between the SIPAT score and nonadherence. A cutoff score of 18 provided optimal specificity (89.6%) and sensitivity (55.6%) for nonadherence. Nonadherence rates were 58.8% and 11.8% for subjects with SIPAT ratings of 18 and above or 17 and below, respectively (relative risk = 4.98, P < .0001). Psychosocial risk as quantified by the SIPAT correlated with SCT recipients' adherence to the post-transplant regimen, suggesting that this instrument can contribute to medical risk stratification models. Further study should evaluate long-term mortality data and the effects of intervention on psychosocial risks.

Immunomodulatory drugs downregulate IKZF1 leading to expansion of hematopoietic progenitors with concomitant block of megakaryocytic maturation.

The immunomodulatory drugs, lenalidomide and pomalidomide yield high response rates in multiple myeloma patients, but are associated with a high rate of thrombocytopenia and increased risk of secondary hematologic malignancies. Here, we demonstrate that the immunomodulatory drugs induce self-renewal of hematopoietic progenitors and upregulate megakaryocytic colonies by inhibiting apoptosis and increasing proliferation of early megakaryocytic progenitors via down-regulation of IKZF1. In this process, the immunomodulatory drugs degrade IKZF1 and subsequently down-regulate its binding partner, GATA1. This results in the decrease of GATA1 targets such as ZFPM1 and NFE2, leading to expansion of megakaryocytic progenitors with concomitant inhibition of maturation of megakaryocytes. The down-regulation of GATA1 further decreases CCND1 and increases CDKN2A expression. Overexpression of GATA1 abrogated the effects of the immunomodulatory drugs and restored maturation of megakaryocytic progenitors. Our data not only provide the mechanism for the immunomodulatory drugs induced thrombocytopenia but also help to explain the higher risk of secondary malignancies and long-term cytopenia induced by enhanced cell cycling and subsequent exhaustion of the stem cell pool.

CXCR4 blockade improves leukemia eradication by allogeneic lymphocyte infusion.

Persistent low levels of disease in bone marrow, an immunoprivileged tissue, are responsible for relapse following allogeneic hematopoietic cell transplantation. Using mouse models carrying primary human acute lymphoblast leukemia derived from MLL-AF9-overexpressing human hematopoietic stem cells, we demonstrate that allogeneic lymphocyte infusion (ALI)-mediated graft-vs.-leukemia effects selectively spare leukemia cells in the bone marrow. The resistance of leukemia cells to ALI within bone marrow is due to the immunosuppressive status of the tissue, as ALI achieved a significantly increased complete remission rate when leukemia cells were dislodged from bone marrow by treatment with a CXCR4 antagonist AMD3100. Adoptive transfer experiments confirmed that the frequency of leukemia-initiating cells in bone marrow was significantly decreased in the recipients treated with ALI plus AMD3100 compared to those receiving ALI only. These findings indicate that the immunoprivileged nature of bone marrow is largely responsible for relapse after immunotherapies, and that treatment with AMD3100 may offer a clinically-practical approach to improving the outcome of adoptive allogeneic cell therapy.

Filgrastim-Induced Crescentic Transformation of Recurrent IgG2λ GN.

Proliferative GN with monoclonal IgG deposits is an increasingly recognized form of GN, but its relation to hematologic malignancy remains poorly understood. Filgrastim, an analog for granulocyte colony-stimulating factor produced by recombinant DNA technology, is frequently used to stimulate bone marrow release of hematopoietic progenitor cells in preparation for stem cell transplant. We report an exceptional case of proliferative GN with monoclonal IgG2λ deposits in a young man whose disease progressed slowly to CKD, which was followed by a preemptive kidney transplant. The patient developed recurrent GN in the allograft and clinically detectable plasma cell neoplasm 9 years after the first renal manifestations. Contemporaneous with filgrastim administration for stem cell mobilization, the patient's slowly progressive GN underwent severe crescentic transformation, leading to rapidly progressive and irreversible allograft failure. This report explores the spectrum of GN with monoclonal IgG deposits and the pathophysiologic role of granulocyte colony-stimulating factor in exacerbation of preexisting GN.