Single-cell analysis of the multiple myeloma microenvironment after gamma-secretase inhibition and CAR T-cell therapy.

Chimeric antigen receptor (CAR) T-cells and bispecific antibodies (BsAb) targeting B-cell maturation antigen (BCMA) have significantly advanced the treatment of relapsed and refractory multiple myeloma (MM). Resistance to BCMA-targeting therapies, nonetheless, remains a significant challenge. BCMA shedding by gamma-secretase is a known resistance mechanism, and preclinical studies suggest that inhibition may improve anti-BCMA therapy. Leveraging a phase I clinical trial of the gamma-secretase inhibitor (GSI), crenigacestat, with anti-BCMA CAR T-cells (FCARH143), we utilized single-nuclei RNA sequencing and Assay for Transposase-Accessible Chromatin (ATAC) sequencing to characterize the effects of GSI on the tumor microenvironment. The most significant impacts of GSI involved effects on monocytes, which are known to promote tumor growth. In addition to observing a reduction in the frequency of non-classical monocytes, we also detected significant changes in gene expression, chromatin accessibility, and inferred cell-cell interactions following exposure to GSI. Although many genes with altered expression are associated with gamma-secretase-dependent signaling, such as Notch, other pathways were affected, indicating GSI has far-reaching effects. Finally, we detected monoallelic deletion of the BCMA locus in some patients with prior exposure to anti-BCMA therapy, which significantly correlated with reduced progression-free survival (median PFS 57 days versus 861 days). GSIs are being explored in combination with the full spectrum of BCMA targeting agents, and our results reveal widespread effects of GSI on both tumor and immune cell populations, providing insight into mechanisms for enhancing BCMA-directed therapies.

Combinatorial antigen targeting strategies for acute leukemia: application in myeloid malignancy.

BACKGROUND AIMS: Efforts to safely and effectively treat acute myeloid leukemia (AML) by targeting a single leukemia-associated antigen with chimeric antigen receptor (CAR) T cells have met with limited success, due in part to heterogeneous expression of myeloid antigens. The authors hypothesized that T cells expressing CARs directed toward two different AML-associated antigens would eradicate tumors and prevent relapse. METHODS: For co-transduction with the authors' previously optimized CLL-1 CAR currently in clinical study (NCT04219163), the authors generated two CARs targeting either CD123 or CD33. The authors then tested the anti-tumor activity of T cells expressing each of the three CARs either alone or after co-transduction. The authors analyzed CAR T-cell phenotype, expansion and transduction efficacy and assessed function by in vitro and in vivo activity against AML cell lines expressing high (MOLM-13: CD123 high, CD33 high, CLL-1 intermediate), intermediate (HL-60: CD123 low, CD33 intermediate, CLL-1 intermediate/high) or low (KG-1a: CD123 low, CD33 low, CLL-1 low) levels of the target antigens. RESULTS: The in vitro benefit of dual expression was most evident when the target cell line expressed low antigen levels (KG-1a). Mechanistically, dual expression was associated with higher pCD3z levels in T cells compared with single CAR T cells on exposure to KG-1a (P < 0.0001). In vivo, combinatorial targeting with CD123 or CD33 and CLL-1 CAR T cells improved tumor control and animal survival for all lines (KG-1a, MOLM-13 and HL-60); no antigen escape was detected in residual tumors. CONCLUSIONS: Overall, these findings demonstrate that combinatorial targeting of CD33 or CD123 and CLL-1 with CAR T cells can control growth of heterogeneous AML tumors.

CD7 CAR T Cells for the Therapy of Acute Myeloid Leukemia.

Chimeric antigen receptor (CAR) T cell therapy for the treatment of acute myeloid leukemia (AML) has the risk of toxicity to normal myeloid cells. CD7 is expressed by the leukemic blasts and malignant progenitor cells of approximately 30% of AML patients but is absent on normal myeloid and erythroid cells. Since CD7 expression by malignant blasts is also linked with chemoresistance and poor outcomes, targeting this antigen may be beneficial for this subset of AML patients. Here, we show that expression of a CD7-directed CAR in CD7 gene-edited (CD7KO) T cells effectively eliminates CD7+ AML cell lines, primary CD7+ AML, and colony-forming cells but spares myeloid and erythroid progenitor cells and their progeny. In a xenograft model, CD7 CAR T cells protect mice against systemic leukemia, prolonging survival. Our results support the feasibility of using CD7KO CD7 CAR T cells for the non-myeloablative treatment of CD7+ AML.

A review of late complications of allogeneic hematopoietic stem cell transplantations.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is an effective and curative treatment of different malignant and non-malignant diseases. Early transplant-related mortality after allo-HSCT has decreased with reduced-intensity conditioning regimens and effective anti-infectious treatments, but late transplant-related mortality is still a problem. Physicians are now paying more attention to late complications that may worsen the quality of life of many transplant recipients. Chronic graft versus host disease (cGVHD) is one of the major causes of late transplant-related mortality after allo-HSCT. This review discusses recent advances that have been made in clinical evaluation and treatment of late transplant-related complications including cGVHD. The different sites of involvement are organs, especially the skin and eye, and the gastrointestinal, endocrinologic, metabolic, renal, cardiologic, pulmonary, connective tissue, and neurological systems. In addition, this review includes infections and secondary malignancies in post-transplant settings that worsen quality of life in long-term follow-ups.

A review of infectious complications after haploidentical hematopoietic stem cell transplantations.

BACKGROUND: Allogeneic hematopoietic stem cell transplantation from haploidentical donor is a feasible option for patients with hematological diseases who lack a suitable HLA-matched donor, but viral and fungal infections are still the most common causes of morbidity and mortality in haploidentical transplantation setting because of delayed immune reconstitution, increased risk of graft vs host disease (GvHD) or systemic steroid use. Therefore, this review will focus on the infectious complications after haploidentical hematopoietic stem cell transplantation (HSCT). MATERIALS AND METHODS: Electronic publications were searched until February 2017 throughout databases, including Pubmed, Cochrane, and Embase. The following keywords were used 'haploidentical transplantation', 'infection', 'T cell replete', and 'T cell deplete'. RESULTS: An increased incidence of bacterial, fungal, or viral infections is detected in haplo-HSCT compared to related, unrelated, or cord blood transplantations. Neutropenia and use of systemic steroid for GvHD and delayed immune reconstitution are important risk factors for infection after haplo-HSCT. CONCLUSION: A shift towards T cell repletes haplo-HSCT with post-transplant cyclophosphamide (CY) for GvHD has been emerged in recent years, in which the incidence of viral and fungal infections is detected to be lower. Prophylaxis and pre-emptive treatment strategies should be applied according to patient status.

An overview of infectious complications after allogeneic hematopoietic stem cell transplantation.

Infections are the most common and significant cause of mortality and morbidity after allogeneic hematopoietic stem cell transplantation (allo-HSCT). The presence of neutropenia and mucosal damage are the leading risk factors in the early pre-engraftment phase. In the early post-engraftment phase, graft versus host disease (GvHD) induced infection risk is increased in addition to catheter related infections. In the late phase, in which reconstitution of cellular and humoral immunity continues, as well as the pathogens seen during the early post-engraftment phase, varicella-zoster virus and encapsulated bacterial infections due to impaired opsonization are observed. An appropriate vaccination schedule following the cessation of immunosuppressive treatment after transplantation, intravenous immunoglobulin administration, and antimicrobial prophylaxis with penicillin or macrolide antibiotics during immunosuppressive treatment for GvHD might decrease the risk of bacterial infections. Older age, severe mucositis due to toxicity of chemotherapy, gastrointestinal tract colonization, prolonged neutropenia, unrelated donor and cord blood originated transplantations, acute and chronic GvHD are among the most indicative clinical risk factors for invasive fungal infections. Mold-active anti-fungal prophylaxis is suggested regardless of the period of transplantation among high risk patients. The novel serological methods, including Aspergillus galactomannan antigen and beta-D-glucan detection and computed tomography are useful in surveillance. Infections due to adenovirus, influenza and respiratory syncytial virus are encountered in all phases after allo-HSCT, including pre-engraftment, early post-engraftment and late phases. Infections due to herpes simplex virus-1 and -2 are mostly seen during the pre-engraftment phase, whereas, infections due to cytomegalovirus and human herpes virus-6 are seen in the early post-engraftment phase and Epstein-Barr virus and varicella-zoster virus infections often after +100th day. In order to prevent mortality and morbidity of infections after allo-HSCT, the recipients should be carefully followed-up with appropriate prophylactic measures in the post-transplant period.

Are we there yet? cellular therapies for cutaneous T cell lymphoma.

Cutaneous T cell lymphomas (CTCLs) are a heterogenous group of skin-involved T-cell non-Hodgkin lymphoma which Mycosis Fungoides and Sezary Syndrome are the most common variants. Despite considerable progress in distinguishing the pathophysiology, the treatment options are still limited for advanced-stage disease. Recent approval of novel agents such as vorinostat, brentuximab vedotin and mogamulizumab paved a way. Allogeneic hematopoietic stem cell transplantation has been shown to be a feasible option in selected advanced-stage CTCL patients. Chimeric antigen receptor (CAR) T cells have been promising for the treatment of B-cell tumors and have been approved for second-line treatment in non-Hodgkin's lymphoma. Although several obstacles still need to be addressed, CAR T cell treatment for CTCLs seems not far off. This review discusses new discoveries in pathophysiology, the state of cellular therapies in current practice, challenges for cellular treatment in advanced CTCL, and how to overcome these challenges.

Resistance against anti-CD19 and anti-BCMA CAR T cells: Recent advances and coping strategies.

Chimeric antigen receptor T (CAR T) cell therapy is a new treatment paradigm that has revolutionized the treatment of CD19-positive B cell malignancies and BCMA-positive plasma cell malignancies. The response rates are highly impressive in comparison to historical cohorts, but the responses are not durable. The most recent results from pivotal trials show that current CAR T cell products fail to demonstrate optimal long-term disease control. Resistance to CAR T cells is related to CAR structure, T cell factors, tumor factors and the immunosuppressive microenvironment. Novel strategies are needed following failure with CAR T cell treatment. In this review, we discuss the resistance mechanisms to CAR T cell treatment according to disease and the emerging strategies to overcome resistance.

Allogeneic stem cell transplantation for relapsed primary central nervous system lymphoma: Is it feasible?

Primary central nervous system lymphoma (PCNSL), has an aggressive course and in untreated patients median survival is limited to three months. For relapsed PCNSL, the treatment options are few and results are usually unsatisfactory. Allogeneic Hematopoietic Stem Cell Transplantation (allo-HCT) has been widely used for treatment of relapsed/refractory NHL patients. However there are limited data whether graft versus lymphoma effect can work in PCNSL patients. Here, we present a relapsed refractory PCNSL case treated by allo-HCT.

Treatment with methotrexate, rituximab, and cytosine arabinoside followed by autologous stem cell transplantation in primary central nervous system lymphoma: A single-center experience.

OBJECTIVE/BACKGROUND: Primary central nervous system lymphoma (PCNSL) is associated with worst prognosis compared with other aggressive non-Hodgkin's lymphomas. However, recent trials have demonstrated that long-term progression-free survival can be achieved by immunochemotherapy. Our goal is to present our experience in aggressive PCNSL in this study. METHODS: We retrospectively evaluated the clinical features and management of 13 PCNSL patients who were diagnosed and treated between 2006 and 2015. RESULTS: Nine patients received rituximab (R) 375mg/m2/day on Day 1, methotrexate (MTX) 3.5g/m2/day and cytosine arabinoside (ARA-C) 4.4g/m2/day on Day 2, as well as ARA-C 4.4g/m2/day on Day 3 every 28days, and underwent autologous stem cell transplantation. Two patients received procarbazine instead of ARA-C. One patient relapsed, and allogeneic hematopoietic stem cell transplantation was performed. All nine patients are followed in complete remission. Two of 13 patients received one course of MTX and 36-45Gy radiotherapy and died. One patient with renal transplantation had progressive disease and died. Grade 3-4 hematological toxicity was detected in 11 (85%), Grade 3-4 mucositis in 11 (85%), and febrile neutropenia in 12 (92%) patients. The median overall survival in the R-MTX-ARA-C/procarbazine group was 28±16months. CONCLUSION: R-MTX-ARA-C followed by autologous stem cell transplantation seems a promising strategy with high response rates in PCNSL.

Upper respiratory viral infections in patients with haematological malignancies after allogeneic haematopoietic stem cell transplantation: a retrospective study.

BACKGROUND: Community respiratory viruses (CRVs) are associated with upper respiratory viral infections (URI), pneumonia or life-threatening respiratory disease in patients with allogeneic haematopoietic stem cell transplantation (allo-HSCT). Our aim is to demonstrate our URI experience related to CRVs after allo-HSCT. METHODS: From January 2013 to November 2015, 39 post allo-HSCT patients with acute URI symptoms were included in the study. We evaluated CRVs by multiplex PCR from nasopharyngeal wash and throat swabs. RESULTS: The median age of the patients was 39 (range 20-67 years). A total of 25 patients (64%) had viral panel positivity at a median 140 days post-transplant (range 3-617 days). The most common agents detected were respiratory syncytial virus (32%) and parainfluenza (32%). The patients with viral panel positivity had significantly lower lymphocyte count (1.05×109/l versus 3.09×109/l; P=0.013). During follow-up, 20 patients (80%) were diagnosed with pneumonia. Patients with concurrent bacterial or fungal infections were more likely to have pneumonia (100% versus 68%; P=0.023). 10 patients (40%) died due to pneumonia and related complications. Lower lymphocyte counts and higher C-reactive protein levels at the time of viral panel positivity were risk factors for mortality (1.5×109/l versus 0.39×109/l, P=0.007; 74.2 versus 199.7, P=0.006). CONCLUSIONS: The viral panel was positive in 64% of patients with acute URI symptoms. Lower lymphocyte count was detected in CRV-positive patients. The onset of concomitant bacterial or fungal infections increased the risk of lower respiratory infection disease. Indeed, prospective studies should be designed for risks and outcomes of CRVs in allo-HSCT recipients.

Is cytomegalovirus a risk factor for haemorrhagic cystitis in allogeneic haematopoietic stem cell transplantation recipients?

BACKGROUND: Haemorrhagic cystitis (HC) is usually a serious complication in allogeneic haematopoietic stem cell transplantation (allo-HSCT) recipients. In this study, our aim was to define risk factors and outcomes for patients with HC in an allo-HSCT setting. METHODS: We retrospectively evaluated 249 allo-HSCTs performed between 2011 and 2016 in our centre. RESULTS: HC was diagnosed in 98 patients (39%) at a median of 119 days (range 5-580) and 91 (93%) of the patients had late onset disease. In univariate analysis, HC was related to cytomegalovirus (CMV) reactivation (P<0.001) and BK viraemia (P<0.001); in multivariate analysis, the presence of CMV reactivation was determined to be an independent risk factor (odds ratio: 22.1; 95% CI 1.73, 282.44; P=0.017). There was no association detected between acute graft versus host disease and patients diagnosed with HC within 100 days of transplant. HC was significantly increased by the presence of myelo-ablative conditioning (odds ratio: 31.28; 95% CI 3.98, 246.87; P=0.001) and BK viraemia (odds ratio: 3.93; 95% Cl 1.10, 14.05; P=0.035) in patients with HC grade II and beyond. Forced hydration was recommended in all patients with grade I HC. Patients with HC and clots were treated with continuous bladder irrigation, and 14 of 44 patients with BK viraemia received cidofovir ± ribavirin. Eight of these patients (57%) responded to treatment. Refractory HC was detected in 17 patients (17%) and resolved by a variety of procedures. CONCLUSIONS: This study suggests that CMV reactivation is associated with increased risk of HC in multivariate analysis, however, this result is not confirmed in patients with HC grade II and beyond.

Current treatment strategies in relapsed/refractory mantle cell lymphoma: where are we now?

The management of relapsed/refractory mantle cell lymphoma remains challenging. Patients with relapsed mantle cell lymphoma have been treated with multi-agent salvage chemotherapies; however, outcomes are poor. Although there have been studies in the relapse/refractory setting, current data indicate that autologous hematopoietic stem cell transplantation may be an especially useful approach in the front line setting in patients in first complete or partial remission following induction chemotherapy. Allogeneic hematopoietic stem cell transplantation is the only curative option, although reduced intensity conditioning in chemo-sensitive relapse or refractory mantle cell lymphoma provides better survival rates. In addition, bortezomib, lenalidomide, temsirolimus, and ibrutinib have opened a new therapeutic era. More randomized trials should be conducted to evaluate the appropriate use of these new molecules. In this review, I discuss autologous and allo-transplant options as well as the data regarding recently approved novel agents in the relapse/refractory setting in patients with MCL.

Allogeneic hematopoietic stem cell transplantation for refractory mycosis fungoides (MF) and Sezary syndrome (SS).

Cutaneous T cell lymphoma is a heterogeneous group of lymphoproliferative disorders with different clinical behavior and prognosis in which malignant T cells accumulate in the skin. In the relapsed/refractory stage, treatment strategy varies depending on clinical perspective. We retrospectively evaluated advanced stage relapse or refractory mycosis fungoides and Sezary syndrome patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) at our hospital. The overall response rate was 25%, while the disease progressed and relapsed after transplant in 38% of patients. Allo-HSCT may be a reasonable treatment option in the relapsed/refractory stage.