Nadim Mahmud

Induction of specific T cell immunity in patients with prostate cancer by vaccination with PSA146–154 peptide

T cell immunotherapy of prostate cancer (CaP) offers the potential for less toxic, more effective outcomes. A clinical trial was conducted in 28 patients with locally advanced or metastatic CaP to determine whether an HLA-A2 binding epitope of prostate-specific antigen, PSA146–154 (PSA-peptide), can induce specific T cell immunity. Patients were vaccinated either by intradermal injection of PSA-peptide and GM-CSF or by intravenous administration of autologous dendritic cells pulsed with PSA-peptide at weeks 1, 4 and 10. Delayed-type hypersensitivity (DTH) skin testing was performed at weeks 4, 14, 26 and 52. Fifty percent of the patients developed positive DTH responses to PSA-peptide. The size of the DTH induration progressively increased over time in the majority of responding patients. Skin biopsies from seven DTH-positive patients were available and T cells that developed in situ were also characterized. The phenotype of recovered T cells demonstrated variable proportions of CD4+CD8−, CD4−CD8+ and CD4+CD8+ T cell populations. Cytokine analysis of PSA-peptide stimulated T cells per bead array assay exhibited specific IFN-γ and TNF-α response in six of seven patients. Specific IL-4 response was observed in five patients, while IL-10 response was detected in one patient. Purified CD4−CD8+ T cells isolated from four patients demonstrated specific cytolytic activity per chromium release assay. In conclusion, immunization with PSA-peptide induced specific T cell immunity in one-half of the patients with locally advanced and hormone-sensitive, metastatic CaP. DTH-derived T cells exhibited PSA-peptide-specific cytolytic activity and predominantly expressed a type-1 cytokine profile.

Nonmyeloablative Stem Cell Transplantation with Alemtuzumab/Low-Dose Irradiation to Cure and Improve the Quality of Life of Adults with Sickle Cell Disease

Allogeneic hematopoietic stem cell transplantation (HSCT) is rarely performed in adult patients with sickle cell disease (SCD). We utilized the chemotherapy-free, alemtuzumab/total body irradiation 300 cGy regimen with sirolimus as post-transplantation immunosuppression in 13 high-risk SCD adult patients between November 2011 and June 2014. Patients received matched related donor (MRD) granulocyte colony-stimulating factor-mobilized peripheral blood stem cells, including 2 cases that were ABO incompatible. Quality-of-life (QoL) measurements were performed at different time points after HSCT. All 13 patients initially engrafted. A stable mixed donor/recipient chimerism was maintained in 12 patients (92%), whereas 1 patient not compliant with sirolimus experienced secondary graft failure. With a median follow-up of 22 months (range, 12 to 44 months) there was no mortality, no acute or chronic graft-versus-host disease (GVHD), and no grades 3 or 4 extramedullary toxicities. At 1 year after transplantation, patients with stable donor chimerism have normalized hemoglobin concentrations and improved cardiopulmonary and QoL parameters including bodily pain, general health, and vitality. In 4 patients, sirolimus was stopped without rejection or SCD-related complications. These results underscore the successful use of a chemotherapy-free regimen in MRD HSCT for high-risk adult SCD patients and demonstrates a high cure rate, absence of GVHD or mortality, and improvement in QoL including the applicability of this regimen in ABO mismatched cases (NCT number 01499888).

Differential effects of epigenetic modifiers on the expansion and maintenance of human cord blood stem/progenitor cells.

Epigenetic therapies, including DNA methyltransferase and histone deacetylase (HDAC) inhibitors, are increasingly being considered to treat hematological malignancies, but their effects on normal hematopoietic stem cells (HSCs) remain largely unexplored. We compared the effects of several HDAC inhibitors, including valproic acid (VPA) and trichostatin A (TSA), alone or in combination with 5-aza-2-deoxycytidine (5azaD) on the expansion of HSCs. VPA induced the highest expansion of CD34+CD90+ cells and progenitor cells compared with other HDAC inhibitors or the sequential addition of 5azaD/TSA in culture. Xenotransplantation studies demonstrated that VPA prevents HSC loss, whereas 5azaD/TSA treatment leads to a net expansion of HSCs that retain serial transplantation ability. 5azaD/TSA-mediated HSC expansion was associated with increased histone acetylation and transient DNA demethylation, which corresponded with higher gene transcript levels. However, some genes with increased transcript levels lacked changes in methylation. Importantly, a global microarray analysis revealed a set of differentially expressed genes in 5azaD/TSA- and VPA-expanded CD34+ cells that might be involved in the expansion and maintenance of transplantable HSCs, respectively. In summary, our data indicate that treatment of HSCs with different chromatin-modifying agents results in either the expansion or maintenance of HSCs, an observation of potential therapeutic importance.

Cord blood stem cell expansion is permissive to epigenetic regulation and environmental cues

OBJECTIVEnAugmentation of the number of cord blood (CB) hematopoietic stem cells (HSC) present in a unit is required before it can be considered as an alternative graft for hematopoietic reconstitution for adult patients. In order to further optimize strategies to augment HSC numbers, we examined whether expansion of HSC mediated by epigenetic mechanisms remains permissive to external environmental cues.nnnMATERIALS AND METHODSnThe chromatin-modifying agents 5-aza-2-deoxycytidine (5azaD) and trichostatin A (TSA) were used to ameliorate epigenetic alteration of CB cells during ex vivo culture by adding various cytokines. After culture, CD34(+)CD90(+) cell numbers, their division history, in vitro clonogenic potential, and in vivo hematopoietic reconstitution potential and frequency were determined.nnnRESULTSn5azaD/TSA-treated, CD34(+)CD90(+) cells were greatly influenced in terms of their degree of expansion, clonogenic potential, cell-division rate, and transplantability by the combination of cytokines used in culture. Furthermore, our current results verify that the sequential addition of 5azaD followed by TSA is crucial for expansion of HSC. We demonstrate that following 5azaD/TSA treatment, the rate of CD34(+)CD90(+) cell division is also dependent on the cytokine cocktail and that this is associated with functional changes, including alteration of in vitro clonogenic potential and in vivo reconstitution potential.nnnCONCLUSIONSnOur studies indicate there are interactions between intrinsic factors influenced by epigenetic mechanisms and external environmental signals in the regulation of HSC expansion. Epigenetic influences on HSC can be accentuated by environmental factors. Regulation of the rate of divisions may be a critical determinant for the maintenance of HSC functional potency during ex vivo expansion.

Combination of Linear Accelerator–Based Intensity-Modulated Total Marrow Irradiation and Myeloablative Fludarabine/Busulfan: A Phase I Study

Here we examined the addition of intensity-modulated total marrow irradiation (TMI) delivered using a linear accelerator to a myeloablative chemotherapy conditioning regimen before allogeneic hematopoietic stem cell transplantation (HSCT). In this phase I study, we enrolled 14 patients with high-risk hematologic malignancies who received escalating doses of TMI at 3xa0Gy (nxa0=xa03), 6xa0Gy (nxa0=xa03), 9xa0Gy (nxa0=xa06), and 12xa0Gy (nxa0=xa02) in combination with intravenous (i.v.) fludarabine 160xa0mg/m(2) and targeted busulfan (area under the curve, 4800xa0μM*minute). Peripheral blood mobilized stem cells were obtained from HLA-matched related (nxa0=xa09) or unrelated (nxa0=xa04) or 1 antigen-mismatched unrelated (nxa0=xa01) donors. All patients rapidly engrafted and recovered their immune cells. Overall, Bearman extrahematologic toxicity were limited to grades 1 or 2, with oral mucositis grade 1 in 64% and grade 2 in 36% of the patients. With a median follow-up of 1126xa0days (range, 362 to 1469) for living patients, the overall survival was 50% and relapse-free survival was 43%. Of 7 deaths, 3 were due to relapse and 4 to transplantation-related complications. We conclude that 9xa0Gy TMI can be combined with myeloablative chemotherapy in the design of new preparative regimens for HSCT. This study was registered at clinicaltrials.gov as NCT00988013.

Ex vivo expansion of human mobilized peripheral blood stem cells using epigenetic modifiers

Epigenetic modifications likely control the fate of hematopoietic stem cells (HSCs). The chromatin‐modifying agents (CMAs), 5‐aza‐2′‐deoxycytidine (5azaD) and trichostatin A (TSA), have previously been shown to expand HSCs from cord blood and marrow. Here we assessed whether CMA can also expand HSCs present in growth factor–mobilized human peripheral blood (MPB).

A phase 1 trial of autologous stem cell transplantation conditioned with melphalan 200 mg/m2 and total marrow irradiation (TMI) in patients with relapsed/refractory multiple myeloma

Abstract In this phase 1 study, we tested increasing doses of total marrow irradiation (TMI) in addition to standard intravenous melphalan at 200u2009mg/m2 (Mel200) in the conditioning regimen prior to autologous stem cell transplant (ASCT) for multiple myeloma (NCT02043847). Twelve patients aged 18–75 with relapsed myeloma were enrolled in the study and received Mel200 and TMI 3u2009Gy (nu2009=u20093), 6u2009Gy (nu2009=u20093), or 9u2009Gy (nu2009=u20096) prior to transplant. There were no grade 4 extra-hematologic toxicities and a maximum tolerated dose was not reached. Median time to neutrophil and platelet engraftment was 11 and 13 d, respectively. At day 90, 73% of patients were in CR or VGPR. Median progression free survival (PFS) was 449 d and median overall survival (OS) was 966 d. We conclude that TMI at a dose of 9u2009Gy can be safely combined with Mel200 in therapeutic regimens for autologous transplant. Initial clinical results will prompt a phase 2 study.

T Cell–Mediated Rejection of Human CD34+ Cells Is Prevented by Costimulatory Blockade in a Xenograft Model

A xenograft model of stem cell rejection was developed by co-transplantating human CD34+ and allogeneic CD3+ T cells into NOD-scid ɣ-chainnull mice. T cells caused graft failure when transplanted at any CD34/CD3 ratio between 1:50 and 1:.1. Kinetics experiments showed that 2 weeks after transplantation CD34+ cells engrafted the marrow and T cells expanded in the spleen. Then, at 4 weeks only memory T cells populated both sites and rejected CD34+ cells. Blockade of T cell costimulation was tested by injecting the mice with abatacept (CTLA4-IgG1) from day -1 to +27 (group A), from day -1 to +13 (group B), or from day +14 to +28 (group C). On day +56 groups B and C had rejected the graft, whereas in group A graft failure was completely prevented, although with lower stem cell engraftment than in controls (Pu2009=u2009.03). Retransplantation of group A mice with same CD34+ cells obtained a complete reconstitution of human myeloid and B cell lineages and excluded latent alloreactivity. In this first xenograft model of stem cell rejection we showed that transplantation of HLA mismatched CD34+ cells may be facilitated by treatment with abatacept and late stem cell boost.