Cryopreserved Ex Vivo-Expanded Allogeneic Myeloid Progenitor Cell Product Protects Neutropenic Mice From a Lethal Fungal Infection.

Severe neutropenia induced by chemotherapy or conditioning for hematopoietic cell transplantation often results in morbidity and mortality due to infection by opportunistic pathogens. A system has been developed to generate ex vivo-expanded mouse myeloid progenitor cells (mMPCs) that produce functional neutrophils in vivo upon transplantation in a pathogen challenge model. It has previously been demonstrated that transplantation of large numbers of freshly isolated myeloid progenitors from a single donor provides survival benefit in radiation-induced neutropenic mice. In the present work, an ex vivo-expanded and cryopreserved mMPC product generated from an allogeneic donor pool retains protective activity in vivo in a lethal fungal infection model. Infusion of the allogeneic pooled mMPC product is effective in preventing death from invasive Aspergillus fumigatus in neutropenic animals, and protection is dose dependent. Cell progeny from the mMPC product is detected in the bone marrow, spleen, blood, and liver by flow cytometry 1 week postinfusion but is no longer evident in most animals 4 weeks posttransplant. In this model, the ex vivo-generated pooled allogeneic mMPC product (i) expands and differentiates in vivo; (ii) is functional and prevents death from invasive fungal infection; and (iii) does not permanently engraft or cause allosensitization. These data suggest that an analogous ex vivo-expanded human myeloid progenitor cell product may be an effective off-the-shelf bridging therapy for the infectious complications that develop during hematopoietic recovery following hematopoietic cell transplantation or intensive chemotherapy.

Comparative cost-effectiveness analysis of voriconazole and fluconazole for prevention of invasive fungal infection in patients receiving allogeneic hematopoietic cell transplants.

PURPOSE: The cost-effectiveness of voriconazole versus fluconazole prophylaxis against fungal infections in hematopoietic cell transplant (HCT) recipients is investigated. METHODS: A decision-analytic model was developed to estimate the drug costs associated with planned or supplemental prophylaxis and empirical therapy and the costs of treating suspected or documented invasive fungal infections (IFIs) in HCT recipients. Published clinical trial data on 599 patients who received 100-180 days of prophylactic therapy with voriconazole or fluconazole were used to model specified IFI-prevention and mortality outcomes; 6-month, 12-month, and lifetime incremental cost-effectiveness ratios (ICERs) were estimated, with a bootstrap analysis performed to reffect the uncertainty of the clinical trial data. RESULTS: Estimated mean total prophylaxis and IFI-related costs associated with voriconazole versus fluconazole prophylaxis over 12 months were higher in the entire study population and among patients receiving HCT for diagnoses other than acute myeloid leukemia (AML) but were not significantly different for patients with AML. The cost per IFI avoided ($66,919) and the cost per life-year gained ($5,453) were lower among patients with AML who received voriconazole relative to the full study population. ICERs were more favorable for voriconazole over a 6-month time frame and when modeling was conducted using generic price data. Assuming a threshold value of $50,000 for one year of life gained, the calculated probability of voriconazole being cost-effective was 33% for the full study population and 85% for the AML subgroup. CONCLUSION: The decision model indicated that voriconazole prophylaxis was cost-effective for patients undergoing allogeneic HCT for AML.

Cryptococcal osteomyelitis and meningitis in a patient with non-hodgkin's lymphoma treated with PEP-C.

The authors present the first case report of a patient with lymphoma who developed disseminated cryptococcal osteomyelitis and meningitis while being treated with the PEP-C (prednisone, etoposide, procarbazine and cyclophosphamide) chemotherapy regimen. During investigation of fever and new bony lesions, fungal culture from a rib biopsy revealed that the patient had cryptococcal osteomyelitis. Further evaluation demonstrated concurrent cryptococcal meningitis. The patient's disseminated cryptococcal infections completely resolved after a full course of antifungal treatment. Cryptococcal osteomyelitis is itself an extremely rare diagnosis, and the unique presentation with concurrent cryptococcal meningitis in our patient with lymphoma was likely due to his PEP-C treatment. It is well recognised that prolonged intensive chemotherapeutic regimens place patients at risk for atypical infections; yet physicians should recognise that even chronic low-dose therapies can put patients at risk for fungal infections. Physicians should consider fungal infections as part of the infectious investigation of a lymphopaenic patient on PEP-C.

Treatment of acyclovir-resistant herpes simplex virus with continuous infusion of high-dose acyclovir in hematopoietic cell transplant patients.

Infection because of herpes simplex virus (HSV) that is resistant to acyclovir (ACV) poses treatment challenges in hematopoietic cell transplant (HCT) patients. We present a series of patients with ACV-resistant HSV following HCT who were successfully treated with continuous infusion high-dose ACV after failing standard treatment regimens for ACV-resistant HSV.

Utility of influenza vaccination for oncology patients.

Every fall and winter, patients with cancer and their families ask oncologists whether they should be vaccinated for influenza. This season, with escalating concerns regarding the novel H1N1 influenza virus and its recently approved vaccine, this question has become more frequent and increasingly urgent. The purpose of this article is to review evidence related to the ability of patients with cancer to mount protective immunological responses to influenza vaccination. The literature on immunogenicity in pediatric and adult patients, those with solid tumors and hematologic malignancies, untreated and actively treated patients, and patients receiving biologic agents is summarized and reviewed. In addition, we report on potential strategies to improve the efficacy of influenza vaccination in patients with cancer, such as the timing of vaccination, use of more than a one-shot series, increasing the antigen dose, and the use of adjuvant therapies. We conclude that there is evidence that patients with cancer receiving chemotherapy are able to respond to influenza vaccination, and because this intervention is safe, inexpensive, and widely available, vaccination for seasonal influenza and the novel H1N1 strain is indicated.

Comparison of polymerase chain reaction of polymorphonuclear leukocytes and plasma identifies patients who control cytomegalovirus infection after hematopoietic cell transplantation.

By use of an automated polymerase chain reaction test of plasma and a qualitative polymerase chain reaction assay on polymorphonuclear leukocytes, we identified a subgroup of hematopoietic cell transplant recipients who were able to control cytomegalovirus infection early after hematopoietic cell transplantation without antiviral therapy. Thirty-one percent of patients had cytomegalovirus DNA detected by qualitative polymerase chain reaction assay but had no cytomegalovirus DNA detected by the automated test; this group maintained a lower peak cytomegalovirus load, compared with the group of patients who had cytomegalovirus DNA detected by both tests (P = .03), suggesting a greater degree of functional immune reconstitution.

Protection against lethal Aspergillus fumigatus infection in mice by allogeneic myeloid progenitors is not major histocompatibility complex restricted.

Invasive fungal infections are a leading cause of morbidity and mortality after myelotoxic chemotherapy or radiation exposure. The resulting depletion of myeloid precursors under these conditions appears to be the factor that limits approaches to accelerate immune reconstitution. In a murine model of myeloablation after radiation exposure, we demonstrated that highly purified common myeloid and granulocyte-monocyte progenitors (CMPs/GMPs) accelerated myeloid recovery and, thus, enhanced innate immunity as measured by survival after a lethal challenge with Aspergillus fumigatus. Of greatest significance was the demonstration that the protection afforded by CMPs/GMPs was not major histocompatibility complex restricted. Furthermore, the effect of CMP/GMP cellular therapy was additive with that of liposomal amphotericin B treatment. These observations greatly expand the potential donor pool and, thus, the clinical utility of CMP/GMP cellular therapy in patients with myeloid depletion.

Stepwise development of committed progenitors in the bone marrow that generate functional T cells in the absence of the thymus.

We identified committed T cell progenitors (CTPs) in the mouse bone marrow that have not rearranged the TCRbeta gene; express a variety of genes associated with commitment to the T cell lineage, including GATA-3, T cell-specific factor-1, Cbeta, and Id2; and show a surface marker pattern (CD44+ CD25- CD24+ CD5-) that is similar to the earliest T cell progenitors in the thymus. More mature committed intermediate progenitors in the marrow have rearranged the TCR gene loci, express Valpha and Vbeta genes as well as CD3epsilon, but do not express surface TCR or CD3 receptors. CTPs, but not progenitors from the thymus, reconstituted the alphabeta T cells in the lymphoid tissues of athymic nu/nu mice. These reconstituted T cells vigorously secreted IFN-gamma after stimulation in vitro, and protected the mice against lethal infection with murine CMV. In conclusion, CTPs in wild-type bone marrow can generate functional T cells via an extrathymic pathway in athymic nu/nu mice.

The influence of the conditions of hematopoietic cell transplantation on infectious complications.

PURPOSE OF REVIEW: The multitude of factors that influence the risk of infection after hematopoietic cell transplantation has been further complicated by the rapid evolution of this therapy in the past 5 years. The degree to which functional immune reconstitution has been achieved reflects the equilibrium reached by the immune systems of the recipient and donor in the context of host non-hematopoietic tissue. Thus immunomodulatory influences on the recipient and the transplanted graft, both before and after hematopoietic cell transplantation, have a profound influence on the incidence and severity of infection. This review of the recent literature contributes to our understanding of how the conditions of hematopoietic cell transplantation influence the timing and nature of infectious complications. RECENT FINDINGS: The main themes of published primary research from 2004 to the present focus on non-myeloablative conditioning regimens and their effects on immune reconstitution after hematopoietic cell transplantation. SUMMARY: A plethora of clinical trials are ongoing, focused on the outcome after conditioning regimens designed to result in less regimen-related toxicity while preserving or enhancing the graft-versus-tumor effect. Given the infancy of these new approaches, it is not possible to make definitive statements regarding the relative risk of serious infection with each therapy. It is clear that a reduction in regimen-related non-infectious complications or mortality does not necessarily ensure a reduction in clinically significant infections. Improvements in early diagnostic and therapeutic options for these infections now bring us to an era of understanding pathogens as probes of the functional reconstitution of immunity.

Exogenous administration of immunomodulatory therapies in hematopoietic cell transplantation: an infectious diseases perspective.

PURPOSE OF REVIEW: In contrast to the recipient of a solid organ transplantation, the immunological competence of recipients of hematopoietic cell transplantation does not correlate well with the administration of non-corticosteroid immunosuppressive agents. This apparent paradox reflects the unique and dynamic conglomeration of factors that affect immune reconstitution after hematopoietic cell transplantation. The following is the second part of a review of the recent primary literature regarding exogenous immunomodulatory influences as they pertain to infections in the setting of hematopoietic cell transplantation. RECENT FINDINGS: The main themes of published primary research from 2004 to the present include the influence of exogenously administered immunomodulatory agents on infectious complications after hematopoietic cell transplantation. SUMMARY: The use of immunomodulatory agents such as monoclonal antibodies directed against lymphocyte antigens in the treatment of hematopoietic malignancy has greatly expanded during the past decade. Separate trials of the potential utility of these agents, particularly in the reduction of graft-versus-host disease, in the setting of hematopoietic cell transplantation have yielded encouraging results. Given the infancy of these new approaches, it is not possible to make definitive statements regarding the relative risk of serious infection with each therapy. It is clear that a reduction in regimen-related non-infectious complications or mortality does not necessarily ensure a reduction in clinically significant infections. Improvements in early diagnostic and therapeutic options for these infections now bring us to an era of understanding pathogens such as cytomegalovirus as probes of the functional reconstitution of immunity.

Single infusion of myeloid progenitors reduces death from Aspergillus fumigatus following chemotherapy-induced neutropenia.

Hematopoietic progenitors committed to the myeloid lineage, the common myeloid and granulocyte-monocyte progenitors (CMP/GMP), have been shown to protect against opportunistic pathogens following myeloablative radiation; however, the efficacy of this approach has not been studied in the setting of chemotherapy-induced neutropenia. In this mouse model, the infusion of CMP/GMP on the day after 5-fluorouracil (5-FU) administration (D+1) resulted in a significant increase in the number of splenic neutrophils by D+8 when compared with 5-FU-only controls (P = .02), the majority of which were CMP/GMP-derived (54%). Moreover, 19% and 28% of neutrophils in the blood and bone marrow, respectively, were CMP/GMP-derived. Survival following intranasal challenge with the fungus Aspergillus fumigatus was significantly higher in CMP/GMP-infused mice than the controls (56% and 33% respectively; P = .019). Thus, a single infusion of CMP/GMP enhances tissue neutrophil content and increases survival against a lethal challenge with A fumigatus in the setting of chemotherapy-induced neutropenia.

Fungal infections in bone marrow transplant patients.

PURPOSE OF REVIEW: Invasive fungal infections have become the leading infectious cause of death in recipients of hematopoietic cell transplantation. Several factors have led to a renaissance in the study of invasive fungal infections. The growing incidence of both commonly encountered as well as emerging pathogens and the lethality of these infections coupled with the unprecedented number of available broad-spectrum antifungal drugs has lent a renewed vigor and enthusiasm to attempts to understand the pathogenesis of these diseases and, by doing so, improve prevention, diagnosis, and treatment. The following is a review of the primary research published from 2003 to the present that is pertinent to invasive fungal infection in the setting of hematopoietic cell transplantation. RECENT FINDINGS: The main themes of published primary research during 2003 to the present include the efficacy and tolerability of antifungal prophylaxis, epidemiologic analyses of risk factors following nonmyeloablative preparative regimens, and more-detailed analyses of nonmyeloid immune responses. SUMMARY: Although few definitive recommendations emerged from the studies during the review period, these investigations do contribute to a greater understanding of the immunobiology of invasive fungal infection and of the utility and limitations of newer antifungal agents in the prophylaxis or treatment of invasive fungal infection.

Common lymphoid progenitors rapidly engraft and protect against lethal murine cytomegalovirus infection after hematopoietic stem cell transplantation.

Lymphoid deficiency after allogeneic hematopoietic cell transplantation (HCT) results in increased susceptibility to infection; however, transplantation of mature lymphocytes frequently results in a serious complication known as graft-versus-host disease (GVHD). Here we demonstrate in mice that both congenic as well as allogeneic transplantation of low numbers of highly purified common lymphoid progenitors (CLPs)-a rare population of lymphoid-lineage-committed bone marrow cells-accelerates immune reconstitution after lethal irradiation and rescue with hematopoietic stem cells (HSCs). After congenic transplantation, 3 x 10(3) CLPs protected against murine cytomegalovirus (MCMV) infection at a level roughly equivalent to 107 unfractionated lymph node cells. In the allogeneic model of matched unrelated donor HSC transplantation, cotransplantation of 3 x 10(3) CLPs protected thymus-bearing as well as thymectomized hosts from MCMV infection and attenuated disease severity. Immunohistochemistry in combination with antibody depletion of T and natural killer (NK) cells confirmed that CLP-derived as well as residual host lymphocytes contribute to antiviral protection. Importantly, transplantation of allogeneic CLPs provided a durable antiviral immunity without inducing GVHD. These data support the potential for composing grafts with committed progenitors to reduce susceptibility to viral infection following HCT.

Myeloid progenitors protect against invasive aspergillosis and Pseudomonas aeruginosa infection following hematopoietic stem cell transplantation.

Myelotoxic treatments for oncologic diseases are often complicated by neutropenia, which renders patients susceptible to potentially lethal infections. In these studies of murine hematopoietic stem cell transplantation (HSCT), cotransplantation of lineage-restricted progenitors known as common myeloid progenitors (CMP) and granulocyte-monocyte progenitors (GMP) protects against death following otherwise lethal challenge with either of 2 pathogens associated with neutropenia: Aspergillus fumigatus and Pseudomonas aeruginosa. Cotransplantation of CMP/GMP resulted in a significant and rapid increase in the absolute number of myeloid cells in the spleen, most of which were derived from the donor CMP/GMP. Despite persistent peripheral neutropenia, improved survival correlated with the measurable appearance of progenitor-derived myeloid cells in the spleen. A marked reduction or elimination of tissue pathogen load was confirmed by culture and correlated with survival. Localization of infection by P aeruginosa and extent of disease was also assessed by in vivo bioluminescent imaging using a strain of P aeruginosa engineered to constitutively express a bacterial luciferase. Imaging confirmed that transplantation with a graft containing hematopoietic stem cells and CMP/GMP reduced the bacterial load as early as 18 hours after infection. These results demonstrate that enhanced reconstitution of a tissue myeloid pool offers protection against lethal challenge with serious fungal and bacterial pathogens.

Prophylactic administration of liposomal amphotericin B is superior to treatment in a murine model of invasive aspergillosis after hematopoietic cell transplantation.

With use of a novel model of invasive Aspergillus fumigatus, the efficacy of prophylactic versus therapeutic administration of liposomal amphotericin B (L-AmB) was tested in C57BL/6 mice. After lethal irradiation and transplantation of whole bone marrow (d 0), animals were challenged with conidia either intravenously or via nasal instillation on d +3 and divided into 3 groups: group I received 5% dextrose in water throughout the study period; group II received L-AmB, 5 mg/kg, beginning on d +4; and group III received L-AmB, 5 mg/kg on d -4, d -2, d 0, and d +2, then daily starting d +4. Groups I and II did not survive intravenous challenge, whereas group III had a 40% survival rate. After nasal instillation of conidia, the survival was 25%, 35%, and 85% for mice in groups I, II, and III, respectively. These results demonstrate that prophylactic administration of L-AmB increased early survival against lethal challenge with A. fumigatus, compared with therapy instituted after infection.