Cord blood NK cells engineered to express IL-15 and a CD19-targeted CAR show long-term persistence and potent antitumor activity

Chimeric antigen receptors (CARs) have been used to redirect the specificity of autologous T cells against leukemia and lymphoma with promising clinical results. Extending this approach to allogeneic T cells is problematic as they carry a significant risk of graft-versus-host disease (GVHD). Natural killer (NK) cells are highly cytotoxic effectors, killing their targets in a non-antigen-specific manner without causing GVHD. Cord blood (CB) offers an attractive, allogeneic, off-the-self source of NK cells for immunotherapy. We transduced CB-derived NK cells with a retroviral vector incorporating the genes for CAR-CD19, IL-15 and inducible caspase-9-based suicide gene (iC9), and demonstrated efficient killing of CD19-expressing cell lines and primary leukemia cells in vitro, with marked prolongation of survival in a xenograft Raji lymphoma murine model. Interleukin-15 (IL-15) production by the transduced CB-NK cells critically improved their function. Moreover, iC9/CAR.19/IL-15 CB-NK cells were readily eliminated upon pharmacologic activation of the iC9 suicide gene. In conclusion, we have developed a novel approach to immunotherapy using engineered CB-derived NK cells, which are easy to produce, exhibit striking efficacy and incorporate safety measures to limit toxicity. This approach should greatly improve the logistics of delivering this therapy to large numbers of patients, a major limitation to current CAR-T-cell therapies.

Adenoviral infections in adult allogeneic hematopoietic SCT recipients: a single center experience

Disseminated adenoviral infection (AI) is associated with profound immunosuppression and poor outcome after allogeneic hematopoietic SCT (allo-HSCT). A better understanding of AI in allo-HSCT recipients can serve as a basis to develop more effective management strategies. We evaluated all adult patients who received allo-HSCT at MD Anderson Cancer Center between 1999 and 2008. Among the 2879 allo-HSCT patients, 73 (2.5%) were diagnosed with AI. Enteritis (26%) and pneumonia (24%) were the most common clinical manifestations; pneumonia was the most common cause of adenovirus-associated death. A multivariable Bayesian logistic regression showed that when the joint effects of all covariates were accounted for, cord blood transplant, absolute lymphocyte count (ALC) ≤ 200/mm(3) and male gender were associated with a higher probability of disseminated AI. The OS was significantly worse for patients with AI that was disseminated rather than localized (median of 5 months vs median of 28 months, P<0.001) and for patients with ALC ≤ 200/mm(3) (P<0.001). Disseminated AI, in patients who received allo-HSCT, is a significant cause of morbidity and mortality. Strategies for early diagnosis and intervention are essential, especially for high-risk patients.

Ex vivo expansion of cord blood

A marked increase in the utilization of umbilical cord blood (UCB) transplantation has been observed in recent years; however, the use of UCB as a hematopoietic stem cell (HSC) source is limited primarily by the number of progenitor cells contained in the graft. Graft failure, delayed engraftment and profound delay in immune reconstitution lead to significant morbidity and mortality in adults. The lack of cells available for post transplant therapies, such as donor lymphocyte infusions, has also been considered to be a disadvantage of UCB. To improve outcomes and extend applicability of UCB transplantation, one potential solution is ex vivo expansion of UCB. Investigators have used several methods, including liquid suspension culture with various cytokines and expansion factors, co-culture with stromal elements and continuous perfusion systems. Techniques combining ex vivo expanded and unmanipulated UCB are being explored to optimize the initial engraftment kinetics as well as the long-term durability. The optimal expansion conditions are still not known; however, recent studies suggest that expanded UCB is safe. It is hoped that by ex vivo expansion of UCB, a resulting decrease in the morbidity and mortality of UCB transplantation will be observed, and that the availability of additional cells may allow adoptive immunotherapy or gene transfer therapies in the UCB setting.

A pilot study CD34 selected haploidentical transplant using a chemotherapy-only preparative regimen and intensive antibiotic prophylaxis for treatment of advanced leukemia

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Background: We present preliminary data of haploidentical transplant for 13 patients (pts) with acute leukemia. Methods: Phase II Study Results: We present preliminary data of haploidentical transplant for 13 patients (pts) with acute leukemia using a chemotherapy-only preparative regimen of Melphalan 140 mg/m2 on day −8; Thiotepa 10 mg/kg on day −7; Fludarabine 40 mg/m2 on days −6, −5, −4, −3; 1.5 mg/kg of rabbit ATG/day days −6, −5, −4, −3. The transplant was administered on day 0 using positive selection of CD34 positive cells by the CliniMACS device as a means of T-cell depletion. All products had <1 × 104 CD3+ T-cells/kg recipient body weight and needed a minimum of 5 × 106 CD34+ cells/kg but preferably >1 × 107 CD34+ cells/kg recipient body weight. Age ranged 23–50 years/median 37 years, four patients were in advanced remission and nine were in refractory relapse. Patients received intensive PCP prophylaxis with sulfamethoxazole-trimethoprim and pentamidine prior to transplant and during pancytopenia; CMV prophylaxis with valganciclovir during the BMT prep and foscarnet while pancytopenic; and with liposomal amphotericin or cancidas for fungal prophylaxis. Two patients had primary graft failure-one survived disease free and one relapsed. One patient died of multiple organ failure prior to engraftment. Median time to engraftment was 15 days (range, 9–26) to 500 neutrophils and 14 days to platelets 20,000 (range, 13–25). Seven patients died of relapse at a median of 10 months (range 2–13 months), and one patient died of a viral infection. Two of 10 patients who engrafted developed grade one acute graft-versus-host (GVHD) and four patients had chronic GVHD (3 limited, 1 extensive). Four patients survive beyond 2 years, without recurrent disease. Conclusions: This report for haploidentical transplant demonstrates that a chemotherapy only preparative regimen can achieve a high rate of engraftment. Infectious complications were minimal with aggressive prophylaxis. Long-term remission are achievable with little risk of severe GVHD with t-cell depletion with use of CliniMACS in haploidentical stem cell transplant.

No significant financial relationships to disclose.

Intravenous (i.v.) busulfan (Bu) plus melphalan (Mel) is a well-tolerated preparative regimen for stem cell transplantation (SCT) in patients (pts) with advanced lymphoid malignancies

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Background: High dose chemotherapy and SCT is an accepted treatment option for pts with relapsed lymphoid malignancies. However, relapse remains a significant problem. A double alkylating regimen of Bu and Mel has been suggested as an effective and myeloablative pre-transplant conditioning regimen. Historically, oral Bu was used and the combination resulted in considerable mucositis and VOD. An i.v. formulation of Bu has been developed that has less pharmacokinetic variability. We are investigating i.v. Bu-Mel in pts with lymphoid malignancies undergoing auto- or allo-SCT. Patients and Methods: The conditioning regimen consists of i.v. Bu 130 mg/m2 over 3 hr daily for 4 days, either as a fixed dose per BSA, or to target an average daily AUC of 5,000 μMol-min ± 12% determined by a test dose of i.v. Bu at 32 mg/m2 given 48 hours prior to the high dose regimen. After the 4 daily Bu doses, there is a rest day, followed by 2 daily doses of Mel at 70mg/m2. Stem cells are infused the following day. Dilantin is given for seizure prophylaxis. GVHD prophylaxis is tacrolimus and methotrexate for pts receiving allo-SCT. Results: Patient characteristics, engraftment, and regimen-related toxicities are listed below: Grade I or II mucositis was the most common regimen-related toxicity. There were no cases of VOD; reversible hyperbilirubinemia was observed in 3 pts receiving allo-SCT. No grade IV toxicity was noted, and there were no regimen-related deaths with longest follow-up of 10 months. All allo-SCT pts had 100% donor chimerism by day 30. 27 pts had i.v. Bu delivered per test dose guidance; 6 pts received fixed dose Bu at 130 mg/m2. The median daily systemic Bu exposure was 4867 μMol-min. Conclusion: Intravenous Bu-Mel is well tolerated, and enables prompt neutrophil and platelet engraftment. Individualized PK-directed dosing of i.v. Bu is feasible, and likely contributes to the low toxicity profile of this regimen. Longer time is needed to assess disease control.

[Table: see text]

No significant financial relationships to disclose.

Acute heart failure in bone marrow transplantation: Impact of intravenous immune globulin as adjuvant therapy

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Background: Little is known regarding management or treatment of cardiac failure after bone marrow transplantation. We investigated the management, treatment and outcome of new onset acute decompensated heart failure (ADHF) after bone marrow transplantation (BMT) with beta blockers, ace-inhibitors and adjuvant intravenous immune globulin (IVIG) therapy. Methods: We retrospectively examined 25 patients with ADHF. Eleven of these patients developed congestive heart failure within 100 days of BMT. Baseline echocardiograms were normal prior to admission and all patients were hospitalized and evaluated for left ventricular ejection fraction (LVEF), and New York Heart Association (NYHA) class. Patients with acute heart failure were treated with standard heart failure medications and patients post-BMT were treated with standard heart failure therapy plus adjuvant (IVIG) (500mg/Kg/day) for 48 hours. Baseline LVEF and NYHA class of 11 patients pre- and post-BMT were compared with LVEF and NYHA class of 14 patients with ADHF that did not receive a BMT. Results: The baseline diagnosis for all patients in the BMT group was NYHA class 4 and post-therapy improved to class 1.2. The baseline diagnosis for all patients in the non-BMT group were NYHA class 3.7 and improved to class 1.2 with medical therapy. The mean LVEF in the BMT group at diagnosis of ADHF was 27.5% and the mean post-therapy with IVIG was 57.6%. The mean baseline LVEF in the group not undergoing BMT and at diagnosis of ADHF was 28.2% and improved post-therapy to 45.2%. Conclusions: Acute decompensated heart failure in the cancer patient is highly treatable with aggressive medical management. Patients with ADHF after BMT and treated with IVIG may have potential clinical benefits with IVIG and standard medical therapy. Significant improvement in LVEF and NYHA were present in the BMT group versus the non-BMT group. These data suggest that BMT outcomes may be improved with routine heart failure management. Further randomized studies should be conducted.

[Table: see text]

No significant financial relationships to disclose.

Ex vivo expansion of umbilical cord blood

The efficacy of cord blood (CB) transplantation is limited by the low cell dose available. Low cell doses at transplant are correlated with delayed engraftment, prolonged neutropenia and thrombocytopenia and elevated risk of graft failure. To potentially improve the efficacy of CB transplantation, approaches have been taken to increase the cell dose available. One approach is the transplantation of multiple cord units, another the use of ex vivo expansion. Evidence for a functional and phenotypic heterogeneity exists within the HSC population and one concern associated with ex vivo expansion is that the expansion of lower 'quality' hematopoietic progenitor cells (HPC) occurs at the expense of higher 'quality' HPC, thereby impacting the reserve of the graft. There is evidence that this is a valid concern while other evidence suggests that higher quality HPC are preserved and not exhausted. Currently, ex vivo expansion processes include: (1) liquid expansion: CD34+ or CD133+ cells are selected and cultured in medium containing factors targeting the proliferation and self-renewal of primitive hematopoietic progenitors; (2) co-culture expansion: unmanipulated CB cells are cultured with stromal components of the hematopoietic microenvironment, specifically mesenchymal stem cells (MSC), in medium containing growth factors; and (3) continuous perfusion: CB HPC are cultured with growth factors in 'bioreactors' rather than in static cultures. These approaches are discussed. Ultimately, the goal of ex vivo expansion is to increase the available dose of the CB cells responsible for successful engraftment, thereby reducing the time to engraftment and reducing the risk of graft failure.

Umbilical cord blood-derived cells for tissue repair

Hematopoietic tissue-derived cells, including stem cells, have been shown to generate solid organ tissue-specific cells. Besides bone marrow and peripheral blood, umbilical cord blood (UCB) has the advantage of being an easily accessible stem cell source provided as a banked cell product. Using the xenogeneic human into NOD/SCID mouse stem cell transplant model preliminary data suggest UCB-derived tissue-specific cells generated in liver, pancreas, CNS and endothelium. In a clinical sex-mismatched UCB transplant setting Y-positive, UCB-derived gastrointestinal epithelial cells and CNS-specific cells have been identified in female patients. The potential therapeutic use of UCB cells for tissue repair is, however, limited by a low total stem cell number available and by HLA-disparity.

Autologous transplantation of ex vivo expanded bone marrow cells grown from small aliquots after high-dose chemotherapy for breast cancer

The collection of small aliquots of bone marrow (BM), followed by ex vivo expansion for autologous transplantation may be less morbid, and more cost-effective, than typical BM or blood stem cell harvesting. Passive elimination of contaminating tumor cells during expansion could reduce reinoculation risks. Nineteen breast cancer patients underwent autotransplants exclusively using ex vivo expanded small aliquot BM cells (900-1200 x 10(6)). BM was expanded in media containing recombinant flt3 ligand, erythropoietin, and PIXY321, using stromal-based perfusion bioreactors for 12 days, and infused after high-dose chemotherapy. Correlations between cell dose and engraftment times were determined, and immunocytochemical tumor cell assays were performed before and after expansion. The median volume of BM expanded was 36.7 mL (range 15.8-87.0). Engraftment of neutrophils greater than 500/microL and platelets greater than 20,000/microL were 16 (13-24) and 24 (19-45) days, respectively; 1 patient had delayed platelet engraftment, even after infusion of back-up BM. Hematopoiesis is maintained at 24 months, despite posttransplant radiotherapy in 18 of the 19 patients. Transplanted CD34(+)/Lin(-) (lineage negative) cell dose correlated with neutrophil and platelet engraftment, with patients receiving greater than 2.0 x 10(5) CD34(+)/Lin(-) cells per kilogram, engrafting by day 28. Tumor cells were observed in 1 of the 19 patients before expansion, and in none of the 19 patients after expansion. It is feasible to perform autotransplants solely with BM cells grown ex vivo in perfusion bioreactors from a small aliquot. Engraftment times are similar to those of a typical 1000 to 1500 mL BM autotransplant. If verified, this procedure could reduce the risk of tumor cell reinoculation with autotransplants and may be valuable in settings in which small stem cell doses are available, eg, cord blood transplants. (Blood. 2000;95:2169-2174)

High-dose therapy with autologous hematopoietic cell support as salvage treatment for patients with breast cancer who have relapsed after previous high-dose chemotherapy

Twenty-six patients with breast cancer who had relapsed after previously receiving high-dose chemotherapy and autologous hematopoietic cell support received a second course of high-dose cytoreductive therapy and autologous hematopoietic cell support as salvage therapy. Several different high-dose therapy regimens were employed for the second transplant, including a radiolabeled immunoconjugate. Two patients died of treatment-related complications. The remaining 24 patients relapsed a median of 126 (range 22-635) days after salvage transplant. All have since died. The median survival after salvage transplant was 362 (range 31-931) days. We conclude that second courses of high-dose therapy as salvage treatment are generally well-tolerated but their efficacy is modest. Alternative treatment strategies are needed for these patients.

Ex-vivo expansion of bone marrow progenitor cells for hematopoietic reconstitution following high-dose chemotherapy for breast cancer

The use of hematopoietic growth factors, stromal monolayers, and frequent medium exchange allows the expansion of hematopoietic progenitors ex-vivo. We evaluated the use of ex-vivo expanded progenitor cells for hematopoietic reconstitution following high dose chemotherapy (HDC) in breast cancer patients. Patients with high-risk Stage II or metastatic breast carcinoma underwent bone marrow aspirations using general anesthesia. A total of 675-1125 x 10(6) mononuclear cells (MNC) were seeded for ex-vivo expansion for 12 days in controlled perfusion bioreactors (Aastrom Biosciences, Inc.). The bone marrow cultures, which included the stromal cells collected with the aspirate, were supplemented with erythropoietin, granulocyte-macrophage-colony stimulating factor (GM-CSF)/IL-3 fusion protein (PIXY 321), and flt3 ligand. Stem cell transplant was performed with expanded cells after HDC. A median bone marrow volume of 52.9 mL (range 42-187 mL) was needed to inoculate the bioreactors. Median fold expansion of nucleated cells (NC) and colony forming unit granulocyte-macrophage (CFU-GM) was 4.9 and 9.5, respectively. The median fold expansion of CD34+lin- and long-term culture-initiating culture (LTC-IC) was 0.42 and 0.32, respectively. Five patients were transplanted with ex-vivo expanded NC. Median days to an absolute neutrophil count > 500/microL was 18 (range 15-22). Median days to a platelet count > 20,000/microl was 23 (range 19-39). All patients had sustained engraftment of both neutrophils and platelets. Immune reconstitution was similar to that seen after HDC and conventional stem cell transplantation. We conclude that ex-vivo expansion of progenitor cells from perfusion cultures of small volume bone marrow aspirates, allows hematopoietic reconstitution after HDC.

Microchimerism and tolerance following intrauterine transplantation and transfusion for alpha-thalassemia-1

A fetus homozygous for alpha-thalassemia-1 was given haploidentical paternal CD34 cells at 13, 19 and 24 weeks' gestation and supported through pregnancy by blood transfusion. The fetal hematocrit ranged between 27 and 47% and between one half and three quarters of this hemoglobin was of recipient (Bart's) type. Intrauterine growth proceeded normally and no significant fetal hydrops was detected. Tests for donor HLA antigens, and alpha-globin DNA, were negative on fetal blood samples drawn before birth. A positive signal for alpha-globin DNA was obtained from cord blood and from marrow obtained at 3 months of age, suggesting that some donor stem cells had persisted in the recipient. The infant's blood mononuclear cells showed little proliferative and no cytotoxic response to the donor while responses to a third party were present. Additional paternal CD34 cells given at 3 months age did not reduce transfusion dependency in the subsequent 6 months. Our results show that repeated transfusions can support an alpha-thalassemia-1 fetus through pregnancy, in this instance without significant birth defects or apparent hypoxic tissue injury. The donor stem cells did not have a survival advantage compared with endogenous stem cells, but appeared to survive in the recipient as judged by the persistence of an alpha-globin DNA signal. In vitro studies of alloreactivity suggest tolerization of the host to the donor's MHC disparity. Future efforts will focus on exploiting this tolerance to improve the level of donor chimerism.

High-dose chemotherapy and autologous bone marrow support as consolidation after standard-dose adjuvant therapy for high-risk primary breast cancer

PURPOSE

We studied high-dose cyclophosphamide, cisplatin, and carmustine (CPA/cDDP/BCNU) with autologous bone marrow support (ABMS) as consolidation after standard-dose adjuvant chemotherapy treatment of primary breast cancer involving 10 or more axillary lymph nodes.

PATIENTS AND METHODS

One hundred two women with stage IIA, IIB, IIIA, or IIIB breast cancer involving 10 or more lymph nodes at surgery were registered; 85 were eligible, treated, and assessable. Patients were treated with four cycles of standard-dose cyclophosphamide, doxorubicin, and fluorouracil (CAF), followed by high-dose CPA/cDDP/BCNU with ABMS.

RESULTS

Actuarial event-free survival for the study patients at a median follow-up of 2.5 years is 72% (95% confidence interval, 56% to 82%). Comparison to three historical or concurrent Cancer and Leukemia Group B (CALGB) adjuvant chemotherapy trials selected for similar patients showed event-free survival at 2.5 years to be between 38% and 52%. Therapy-related mortality was 12%; pulmonary toxicity of variable severity occurred in 31% of patients. Quality-of-life evaluations indicate that patients are functioning well without major impairments.

CONCLUSION

High-dose consolidation with CPA/cDDP/BCNU and ABMS after standard-dose CAF results in a decreased frequency of relapse in patients with high-risk primary breast cancer compared with historical series at the median follow-up of 2.5 years. Evaluation in a prospective, randomized trial is warranted and currently underway.