Adoptive cell therapy for high grade gliomas using simultaneous temozolomide and intracranial mgmt-modified γδ t cells following standard post-resection chemotherapy and radiotherapy: current strategy and future directions.

Cellular therapies, including chimeric antigen receptor T cell therapies (CAR-T), while generally successful in hematologic malignancies, face substantial challenges against solid tumors such as glioblastoma (GBM) due to rapid growth, antigen heterogeneity, and inadequate depth of response to cytoreductive and immune therapies, We have previously shown that GBM constitutively express stress associated NKG2D ligands (NKG2DL) recognized by gamma delta (γδ) T cells, a minor lymphocyte subset that innately recognize target molecules via the γδ T cell receptor (TCR), NKG2D, and multiple other mechanisms. Given that NKG2DL expression is often insufficient on GBM cells to elicit a meaningful response to γδ T cell immunotherapy, we then demonstrated that NKG2DL expression can be transiently upregulated by activation of the DNA damage response (DDR) pathway using alkylating agents such as Temozolomide (TMZ). TMZ, however, is also toxic to γδ T cells. Using a p140K/MGMT lentivector, which confers resistance to TMZ by expression of O(6)-methylguanine-DNA-methyltransferase (MGMT), we genetically engineered γδ T cells that maintain full effector function in the presence of therapeutic doses of TMZ. We then validated a therapeutic system that we termed Drug Resistance Immunotherapy (DRI) that combines a standard regimen of TMZ concomitantly with simultaneous intracranial infusion of TMZ-resistant γδ T cells in a first-in-human Phase I clinical trial (NCT04165941). This manuscript will discuss DRI as a rational therapeutic approach to newly diagnosed GBM and the importance of repeated administration of DRI in combination with the standard-of-care Stupp regimen in patients with stable minimal residual disease.

Ex vivo T-cell depletion in allogeneic hematopoietic stem cell transplant: past, present and future.

The most common cause of post-transplant mortality in patients with hematological malignancy is relapse, followed by GvHD, infections, organ toxicity and second malignancy. Immune-mediated complications such as GvHD continue to be challenging, yet amenable to control through manipulation of the T-cell compartment of the donor graft with subsequent immunomodulation after transplant. However, risk of both relapse and infection increase concomitantly with T-cell depletion (TCD) strategies that impair immune recovery. In this review, we discuss the clinical outcome of current and emerging strategies of TCD in allogeneic hematopoietic stem cell transplant that have developed during the modern transplantation era, focusing specifically on ex vivo strategies that target selected T-cell subsets.

Long term disease-free survival in acute leukemia patients recovering with increased gammadelta T cells after partially mismatched related donor bone marrow transplantation.

Allogeneic stem cell transplantation (ASCT) has improved leukemia-free survival (LFS) in many but not all patients with acute leukemia. This is an eight-year follow-up to our previous study showing a survival advantage to patients with an increased gammadelta T cells following ASCT. gammadelta T cell levels were collected prospectively in 153 patients (acute lymphoblastic leukemia (ALL) n = 77; acute myelogenous leukemia (AML) n = 76) undergoing partially mismatched related donor ASCT. Median age was 22 years (1-59), and 62% of the patients were in relapse at transplant. Patient-donor human leukocyte antigen (HLA) disparity of three antigens was 37% in the graft-versus-host disease (GvHD) and 29% in the rejection directions. All patients received a partially T cell-depleted graft using T10B9 (n = 46) or OKT3 (n = 107). Five years LFS and overall survival (OS) of patients with increased gammadelta compared to those with normal/decreased numbers were 54.4 vs 19.1%; P < 0.0003, and 70.8 vs 19.6% P < 0.0001, respectively, with no difference in GvHD (P = 0.96). In a Cox multivariate analysis, normal/decreased gammadelta (hazard ratio (HR) 4.26, P = 0.0002) and sex mismatch (HR 1.45 P=0.049) were associated with inferior LFS. In conclusion, gammadelta T cells may facilitate a graft-versus-leukemia (GvL) effect, without causing GvHD. Further evaluations of this effect may lead to specific immunotherapy for patients with refractory leukemia.

CD69 expression as an index of T-cell function: assay standardization, validation and use in monitoring immune recovery.

BACKGROUND: CD69 is a surrogate marker of T-cell responsiveness to mitogen and Ag stimulus and can be used as a measure of T-lymphocyte activation. Quantitative flow cytometric determination of CD69 expression on T lymphocytes has several advantages over traditional lymphocyte proliferation assays, but this method has not yet been standardized for clinical applications. METHODS: We qualified a commercially available assay using the manufacturer's procedures for measurement of T-cell response to a mitogen (PHA), superantigen (Staphylococcus endotoxin B; SEB) and Ca(2+) ionophore (phorbyl myristate acetate; PMA) with peripheral blood from healthy volunteers. Following this, we tested the usefulness of the assay in determining T-cell responses to PHA and SEB for six immunocompromised patients. RESULTS: Healthy volunteers showed 17-fold increases in T-cell CD69 Ab bound per cell (ABC) with PHA stimulation compared with the baseline. SEB was also an effective T-cell activating agent, increasing CD69 ABC by 5-fold, comparable with results obtained with PMA stimulation. PHA- and SEB-stimulated T-cell CD69 ABC for patients 100 days post-BM transplant were generally below 1 SD of that from healthy volunteers. SEB-stimulated T-cell CD69 expression was significantly depressed for CD8(+) T cells while CD4(+) T-cell responses to SEB were generally within 1 SD of the mean for healthy volunteers. DISCUSSION: These results suggest that quantitative measurement of CD69 surface expression by flow cytometry is a useful diagnostic tool for detailed assessment of T-lymphocyte and subset activation.

In vitro interactions between gamma deltaT cells, DC, and CD4+ T cells; implications for the immunotherapy of leukemia.

BACKGROUND: Gamma deltaT cells contribute to immune defense against infectious organisms and some malignancies, but the process of activation and proliferation of these cells is not well understood. It is known that the immune response of gamma deltaT cells is not MHC-dependent, but is likely based on direct recognition of surface peptides and non-peptide ligands. This study examined whether DCs and CD4(+) T cells can participate in the activation of gamma deltaT cells. METHOD: Peripheral blood gamma deltaT cells were co-cultured with CD34-derived autologous DCs and CD4(+) T cells using contact-dependent cultures and transwell systems. Proliferation, immunophenotyping, and cytotoxicity assays determined the extent of gamma deltaT cell proliferation and cytotoxicity. RESULTS: Human gamma deltaT cells expanded 221.3 +/- 76-fold in cultures with DCs, and 165.7 +/- 76.6-fold with CD4(+) T-cells alone. Proliferation was enhanced (1949.8 +/- 261.3-fold) when gamma deltaT cells were cultured with both DC and CD4(+) T cells. Proliferation was contact-dependent, and resulted in the expansion of V delta1+ or V delta2+ cells cytotoxic against several leukemic cell-lines, but not against allogeneic PHA-induced lymphoid blasts. Ligation of the T-cell receptor with anti-pan-delta Ab significantly up-regulated cytotoxicity against K562, KBM-5 and KG1a, and normal BM, but not against Molt-4, allogeneic EBV-transfected B cells and allogeneic PHA-blasts. Minimal cytotoxic activity was shown against allogeneic marrow colony-forming units granulocyte-macrophage and erythrocyte colony-forming units. CONCLUSION: DCs can participate in the activation of gamma deltaT cells against specific autologous targets, and cytotoxicity can be enhanced by further stimulation via the T-cell receptor.

Human gammadelta(+) T lymphocytes have in vitro graft vs leukemia activity in the absence of an allogeneic response.

Refractory acute lymphoblastic leukemia (ALL) is often incurable, and relapse rates following allogeneic bone marrow transplantation (BMT) remain high. We have reported that patients who develop increased numbers of gammadelta(+) T cells soon after BMT are significantly less likely to relapse. We now show in seven donor/recipient pairs that donor-derived Vdelta1(+)CD4(-)CD8(-)gammadelta(+) T cells are activated and proliferate in response to recipient primary ALL blasts. In addition, these cells have been shown to bind and lyse the recipient ALL blasts. Separately, gammadelta(+) T cells proliferate poorly or not at all in mixed lymphocyte culture against HLA-mismatched unrelated stimulator cells. These observations suggest that allogeneic gammadelta(+) T cells could be an effective immunotherapeutic strategy against refractory disease without the risk of graft-versus-host disease.

Expression of CD134 (0X-40) on T cells during the first 100 days following allogeneic bone marrow transplantation as a marker for lymphocyte activation and therapy-resistant graft-versus-host disease.

CD134 (OX-40) is an activation-associated antigen which functions as a costimulatory receptor for CD4+ T cells. In order to determine the expression of CD134 during immune recovery following allogeneic bone marrow transplantation (BMT), we measured its expression on T cells and T cell subsets during the first 100 days following BMT in 26 patients. CD4+CD134+ T could be seen approximately 14 days following BMT cells in patients who did not develop GvHD which required therapy (n = 20). The percentage of CD4+CD134+ cells continued to increase up to the fourth week following BMT to a maximum of 40-50% of CD4+ T cells (normal = 1-8%). Two patients who developed Grade I-II GvHD and who responded to treatment with pulsed high-dose methylprednisolone (MPD) showed a decline of approximately 40% in CD4+CD134+ T cells was seen within 48 hours of treatment. Four patients who developed GvHD that was not responsive to MPD and who later developed high IV GvHD showed increasing CD4+CD134+ T cells up to 85% of the CD4+ T cells. Additionally, rapid increases in CD134+ T cells following antibody-based T cell therapy were associated with GvHD recurrence. In no cases was the percentage of CD134+ CD4+ T cells predictive of clinical GvHD. In this exploratory study, we have shown that CD134, although not predictive of the initial onset of GvHD, may be a useful tool for monitoring the response to early GvHD therapy and identification of patients at risk for reemergence of GvHD who may benefit from anti-T cell therapy. Cytometry (Comm. Clin. Cytometry) 38: 238-243, 1999.

Influence of T cell depletion method on circulating gammadelta T cell reconstitution and potential role in the graft-versus-leukemia effect.

BACKGROUND: Our laboratory previously reported that leukemia patients who developed > or = 10% gammadelta+ T cells during the first six months after receiving an anti-TCRalphabeta T-cell-depleted (TCD) graft from a partially mismatched related donor (PMRD) had a disease-free survival (DFS) advantage. These gammadelta+ T cells were V81+CD3+CD4-CD8-CD69+HLADR+ and are cytotoxic to K562 cells. METHODS: In order to determine whether the anti-alphabeta TCD regimen was associated with these findings, we compared the reconstitution of gammadelta+ T cells from patients who received TCD PMRD grafts using the anti-TCRc4 MAb TIOB9-1A31 (previously reported) with similar patients who received grafts using the anti-CD3 MAb OKT3. RESULTS: Increased cytotoxic Vdelta1+ T cells were seen in 10 of 43 T10B9 TCD patients compared to 7 of 100 in the OKT3 TCD group (23% versus 7%, p = 0.010). T10B9 patients with increased gammadelta+ T cells also exhibited a higher range of increased gammadelta+ T cells and the length of time the gammadelta+ T cells remained high was longer when compared to OKT3 patients. Patients with increased gammadelta+ T cells whose grafts were T-cell depleted with T10B9 showed a significant decrease in relapse (p = 0.038). Similar rates and reduction in relapse were seen in OKT3 TCD patients, although significance was not reached due to the small number of patients with increased gammadelta+ T cells. Estimated 3 year disease-free survival was significantly improved in T10B9 patients with increased gammadelta+ T cells (0.79 versus 0.31, p = 0.009), a trend also seen in OKT3 patients (p = 0.091). DISCUSSION: These observations indicate that Vdelta1+CD4-CD8-cytotoxic T cells are associated with lower relapse rates and improved survival, and thus may have a role in a graft-versus-leukemia effect.

Donor leukocyte infusion for treatment of graft rejection post partially mismatched related donor bone marrow transplant.

Graft rejection following bone marrow transplantation is more common in patients who receive their grafts from alternative donors and whose marrow is T cell depleted. Rejection in these patients is mediated by persistent host cells that interfere with successful establishment of donor-derived hematopoietic recovery. We describe a patient with chronic myelogenous leukemia in accelerated phase who rejected a T cell-depleted bone marrow graft, 2 months following partially mismatched related donor bone marrow transplant. Unmanipulated peripheral blood donor leukocyte infusion, without additional chemotherapy or immunosuppressive therapy resulted in complete hematopoietic recovery. Cytogenetics and RFLP demonstrated hematopoietic donor chimerism. The patient did not develop graft-versus-host disease.

Phenotypic and functional reconstitution of peripheral blood lymphocytes following T cell-depleted bone marrow transplantation from partially mismatched related donors.

Myeloablative chemotherapy followed by transplantation of a T cell-depleted bone marrow graft from a partially mismatched related donor provides a potentially curative option for patients with leukemia and other disorders of hematopoiesis, although the patient is faced with a period of sustained immunodeficiency as well as pharmacologic immunosuppression as a result of prophylaxis against graft-versus-host disease. Thirty patients who received one to three antigen T cell-depleted mismatched grafts were evaluated for immune reconstitution. The percentage and numbers of cells expressing lymphocyte subset antigens were determined by flow cytometry at 14, 28, 60, 100, 180, 270 and 365 days post-BMT and at 6 month intervals thereafter. Lymphocyte reconstitution was characterized by the early appearance of natural killer cells and a low percentage of both T and B cells. During the first year after BMT, the number of NK cells remained constant while T and B cells gradually returned to normal numbers and proportions. Response to the lymphocyte mitogen phytohemagglutinin returned to normal over the course of 2 years, while the response to concanavalin A was slightly depressed and the response to pokeweed mitogen became supranormal at about 1.5 years and continued to increase. These data suggest the need for long-term immunophenotypic monitoring as well as prolonged infection surveillance and prophylaxis.

Flow cytometric cell sorting combined with molecular chimerism analysis to detect minimal recurrent leukemia: good news and bad news.

Allogeneic BMT offers the possibility of cure for a variety of hematopoietic malignancies, but disease relapse remains a major cause of treatment failure. This report describes two cases in which flow cytometric cell sorting (FACS) and molecular chimerism analysis were combined to increase the sensitivity of minimal residual disease (MRD) detection. In the first case this approach was used to demonstrate that a suspicious phenotype was not recurrent leukemia, thus preventing the use of potentially toxic therapy. In the second case the recurrence of a leukemia which was undetectable by conventional analysis was confirmed. The potential benefits of combining these MRD detection methods are discussed.

De novo chronic graft-versus-host disease presenting as hemolytic anemia following partially mismatched related donor bone marrow transplant .

Chronic graft-versus-host disease (cGVHD) is a disease of immune dysregulation that resembles an autoimmune disease. It usually involves the skin, mucosal and serosal surfaces and, less commonly, the hematopoietic system. We report hemolytic anemia (HA) as the primary manifestation of de novo cGVHD in recipients of partially mismatched related donor transplants. Five of 40 eligible patients developed HA at a median of 168 days post-transplant. Recipients were mismatched for one to three major HLA antigens. Conditioning therapy consisted of total body irradiation, etoposide, Ara-C, cycle-phosphamide and steroids. GVHD prophylaxis included partial T cell depletion, using anti alpha/beta CD3 antibody (T10B9) and complement, in addition to post-transplant immunosuppression. At presentation, all patients were receiving cyclosporine with or without low-dose steroids. Along with a mean Hb of 7.1 g%, patients had an increased reticulocyte count, a mild raised lactic dehydrogenase and a positive Coombs' test (in 2/5 patients). Four patients had also demonstrated a decrease in platelet count. Treatment was initiated with high-dose steroids and intravenous gamma globulin and response was observed within 1 week. Awareness of this presentation of cGVHD and early therapeutic intervention can result in successful reversal of presumed immune-mediated red cell and platelet destruction.

In vitro expansion and characterization of dendritic cells derived from human bone marrow CD34+ cells.

Dendritic cells (DC), as professional antigen-presenting cells, play a major role in stimulating naive T cell responses in vivo and in vitro, and may exacerbate or modulate T lymphocyte-mediated reactions, such as interactions between a hematopoietic graft and the recipient, eg GVHD and graft-versus-leukemia. Here, we describe a two-stage cell culture system for expansion of functionally active human DC from CD34+ marrow precursors. Optimal outgrowth was achieved by initially culturing CD34+ cells for 5 days in medium containing GM-CSF, MGF and TNF-alpha. Substitution of CD40L and IL-4 for TNF-alpha during a subsequent 5-day subculture increased DC content, such that by 10 days the cultures contained approximately 40% DC as determined by immunophenotype and morphology. An increase in DC purity to 84% at 10 days was achieved by immunomagnetic separation for CD1a+ cells from 5-day cultures and subculturing these cells in medium with IL-4 and CD40L. Reversing the sequence of growth factors during culture and subculture decreased the yield and purity of DC. Expression of CD80 and CD86 was enhanced by adding CD40L and IL-4, and the DC showed stimulatory activity in MLC. In conclusion, we have described a simple two-stage culture system to generate functional DC from CD34+ marrow precursors.

Increased frequency of TCR gamma delta + T cells in disease-free survivors following T cell-depleted, partially mismatched, related donor bone marrow transplantation for leukemia.

Recent interest has focused on the function of gamma delta + T cells in immune responses. However, their role in allogeneic bone marrow transplantation (BMT) remains undefined. We report on a group of 43 leukemia patients who survived for at least 100 days following transplantation using partially HLA-mismatched grafts from related donors that were T cell depleted with the anti-TCR alpha beta monoclonal antibody T10B9.1A-31 and complement. Ten patients (23.2%) were found to have an increased (> or = 10%) proportion of gamma delta + T cells in the peripheral blood at 60-270 days after BMT. All of these patients remain alive, and 9 (90% of patients with > or = 10% gamma delta + cells) are free of disease at 2.5 years compared with a disease-free survival probability of 31% among patients with a normal proportion and concentration of gamma delta + T cells. No other factor was found to be independently associated with improved survival in these patients. These data suggest a possible association between an increase in the percentage and number of gamma delta + T cells and improved disease-free survival following transplantation from a partially mismatched related donor.

Acute rejection of marrow grafts in patients transplanted from a partially mismatched related donor: clinical and immunologic characteristics.

Bone marrow transplantation (BMT) from a partially mismatched related donor (PMRD) provides a treatment option for patients lacking a matched sibling donor. T lymphocyte depletion of the graft reduces the risk of severe graft-versus-host disease, but may increase the risk of graft failure. We evaluated the pattern of acute graft rejection in eight patients receiving PMRD BMT with respect to the conditioning therapy, diagnosis, age and sex of donor and recipient, degree of HLA mismatch, and peripheral blood immunophenotype at the time of graft failure. All grafts were partially depleted of T lymphocytes. Marrow grafts infused into patients who experienced acute rejection did not differ significantly in nucleated cell dose, degree of T lymphocyte depletion, T cell dose, or CFU-GM/kg infused, from those received by 31 patients who showed durable engraftment. In three of four patients who rejected their grafts, and had sufficient peripheral blood cells for immunophenotyping, a CD3+CD8+ T lymphocyte phenotype was predominant at the time of acute rejection. In one patient rejection was associated with a predominant population of CD3+CD4+ T lymphocytes. Rejection was significantly associated with chronic myelogeneous leukemia and in patients mismatched by more than two antigens.