Agnieszka Czechowicz

All Publications

• Immune Sparing Conditioning for BMT/HSCT Using Anti-Ckit Immunotoxins Czechowicz, A., Palchaudhuri, R., Scheck, A., Hu, Y., Winau, F., Hoggatt, J., Saez, B., Mansour, M. K., Sykes, D., Scadden, D., Rossi, D. ELSEVIER SCIENCE INC. 2018: S60–S61

  View details for Web of Science ID 000425476000058

• Efficient transplantation via antibody-based clearance of hematopoietic stem cell niches SCIENCE Czechowicz, A., Kraft, D., Weissman, I. L., Bhattacharya, D. 2007; 318 (5854): 1296-1299

  Abstract

  Upon intravenous transplantation, hematopoietic stem cells (HSCs) can home to specialized niches, yet most HSCs fail to engraft unless recipients are subjected to toxic preconditioning. We provide evidence that, aside from immune barriers, donor HSC engraftment is restricted by occupancy of appropriate niches by host HSCs. Administration of ACK2, an antibody that blocks c-kit function, led to the transient removal of >98% of endogenous HSCs in immunodeficient mice. Subsequent transplantation of these mice with donor HSCs led to chimerism levels of up to 90%. Extrapolation of these methods to humans may enable mild but effective conditioning regimens for transplantation.

  View details for DOI 10.1126/science.1149726

  View details for Web of Science ID 000251086600042

  View details for PubMedID 18033883

  View details for PubMedCentralID PMC2527021

• Selective HSC-Ablation Using CD117 Antibody-Drug-Conjugates Enables Safe and Effective Murine and Human Hematopoietic Stem Cell Transplantation Czechowicz, A., Palchaudhuri, R., Scheck, A., Hu, Y., Hoggatt, J., Saez, B., Pang, W. W., Mansour, M. K., Shizuru, J. A., Winau, F., Scadden, D. T., Rossi, D. J. CELL PRESS. 2018: 23–24

  View details for Web of Science ID 000435342200045

• Safe and Effective Platelet-Targeted Gene Therapy of Hemophilia A Enabled Using Non-Genotoxic, Antibody-Drug-Conjugate Conditioning Gao, C., Schroeder, J., Czechowicz, A., Shi, Q. CELL PRESS. 2018: 25

  View details for Web of Science ID 000435342200048

• Anti-Human CD117 Antibodies Mediate Clearance of Myelodysplastic Syndrome Hematopoietic Stem Cells and Facilitate Establishment of Normal Hematopoiesis in Transplantation Pang, W. W., Czechowicz, A., Poyser, J., Park, C. Y., Weissman, I. L., Shizuru, J. A. ELSEVIER SCIENCE INC. 2018: S230–S231

  View details for Web of Science ID 000425476000317

• Non-genotoxic conditioning for hematopoietic stem cell transplantation using a hematopoietic-cell-specific internalizing immunotoxin NATURE BIOTECHNOLOGY Palchaudhuri, R., Saez, B., Hoggatt, J., Schajnovitz, A., Sykes, D. B., Tate, T. A., Czechowicz, A., Kfoury, Y., Ruchika, F. N., Rossi, D. J., Verdine, G. L., Mansour, M. K., Scadden, D. T. 2016; 34 (7): 738-?

  Abstract

  Hematopoietic stem cell transplantation (HSCT) offers curative therapy for patients with hemoglobinopathies, congenital immunodeficiencies, and other conditions, possibly including AIDS. Autologous HSCT using genetically corrected cells would avoid the risk of graft-versus-host disease (GVHD), but the genotoxicity of conditioning remains a substantial barrier to the development of this approach. Here we report an internalizing immunotoxin targeting the hematopoietic-cell-restricted CD45 receptor that effectively conditions immunocompetent mice. A single dose of the immunotoxin, CD45-saporin (SAP), enabled efficient (>90%) engraftment of donor cells and full correction of a sickle-cell anemia model. In contrast to irradiation, CD45-SAP completely avoided neutropenia and anemia, spared bone marrow and thymic niches, enabling rapid recovery of T and B cells, preserved anti-fungal immunity, and had minimal overall toxicity. This non-genotoxic conditioning method may provide an attractive alternative to current conditioning regimens for HSCT in the treatment of non-malignant blood diseases.

  View details for DOI 10.1038/nbt.3584

  View details for Web of Science ID 000381335400028

  View details for PubMedID 27272386

  View details for PubMedCentralID PMC5179034

• A trial of plerixafor adjunctive therapy in allogeneic hematopoietic cell transplantation with minimal conditioning for severe combined immunodeficiency PEDIATRIC TRANSPLANTATION Dvorak, C. C., Horn, B. N., Puck, J. M., Czechowicz, A., Shizuru, J. A., Ko, R. M., Cowan, M. J. 2014; 18 (6): 602-608

  View details for DOI 10.1111/petr.12309

  View details for Web of Science ID 000340530800017

• A trial of alemtuzumab adjunctive therapy in allogeneic hematopoietic cell transplantation with minimal conditioning for severe combined immunodeficiency PEDIATRIC TRANSPLANTATION Dvorak, C. C., Horn, B. N., Puck, J. M., Adams, S., Veys, P., Czechowicz, A., Cowan, M. J. 2014; 18 (6): 609-616

  Abstract

  For infants with SCID the ideal conditioning regimen before allogeneic HCT would omit cytotoxic chemotherapy to minimize short- and long-term complications. We performed a prospective pilot trial with alemtuzumab monotherapy to overcome NK-cell mediated immunologic barriers to engraftment. We enrolled four patients who received CD34-selected haploidentical cells, two of whom failed to engraft donor T cells. The two patients who engrafted had delayed T-cell reconstitution, despite rapid clearance of circulating alemtuzumab. Although well-tolerated, alemtuzumab failed to overcome immunologic barriers to donor engraftment. Furthermore, alemtuzumab may slow T-cell development in patients with SCID in the setting of a T-cell depleted graft.

  View details for DOI 10.1111/petr.12310

  View details for Web of Science ID 000340530800018

  View details for PubMedID 24977928

  View details for PubMedCentralID PMC4134761

• In utero depletion of fetal hematopoietic stem cells improves engraftment after neonatal transplantation in mice. Blood Derderian, S. C., Togarrati, P. P., King, C., Moradi, P. W., Reynaud, D., Czechowicz, A., Weissman, I. L., MacKenzie, T. C. 2014; 124 (6): 973-980

  Abstract

  Although in utero hematopoietic cell transplantation is a promising strategy to treat congenital hematopoietic disorders, levels of engraftment have not been therapeutic for diseases in which donor cells have no survival advantage. We used an antibody against the murine c-Kit receptor (ACK2) to deplete fetal host hematopoietic stem cells (HSCs) and increase space within the hematopoietic niche for donor cell engraftment. Fetal mice were injected with ACK2 on embryonic days 13.5 to 14.5 and surviving pups were transplanted with congenic hematopoietic cells on day of life 1. Low-dose ACK2 treatment effectively depleted HSCs within the bone marrow with minimal toxicity and the antibody was cleared from the serum before the neonatal transplantation. Chimerism levels were significantly higher in treated pups than in controls; both myeloid and lymphoid cell chimerism increased because of higher engraftment of HSCs in the bone marrow. To test the strategy of repeated HSC depletion and transplantation, some mice were treated with ACK2 postnatally, but the increase in engraftment was lower than that seen with prenatal treatment. We demonstrate a successful fetal conditioning strategy associated with minimal toxicity. Such strategies could be used to achieve clinically relevant levels of engraftment to treat congenital stem cell disorders.

  View details for DOI 10.1182/blood-2014-02-550327

  View details for PubMedID 24879814

• Anti-KIT monoclonal antibody inhibits imatinib-resistant gastrointestinal stromal tumor growth PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Edris, B., Willingham, S. B., Weiskopf, K., Volkmer, A. K., Volkmer, J., Muehlenberg, T., Montgomery, K. D., Contreras-Trujillo, H., Czechowicz, A., Fletcher, J. A., West, R. B., Weissman, I. L., van de Rijn, M. 2013; 110 (9): 3501-3506

  Abstract

  Gastrointestinal stromal tumor (GIST) is the most common sarcoma of the gastrointestinal tract and arises from the interstitial cells of Cajal. It is characterized by expression of the receptor tyrosine kinase CD117 (KIT). In 70-80% of GIST cases, oncogenic mutations in KIT are present, leading to constitutive activation of the receptor, which drives the proliferation of these tumors. Treatment of GIST with imatinib, a small-molecule tyrosine kinase inhibitor, inhibits KIT-mediated signaling and initially results in disease control in 70-85% of patients with KIT-positive GIST. However, the vast majority of patients eventually develop resistance to imatinib treatment, leading to disease progression and posing a significant challenge in the clinical management of these tumors. Here, we show that an anti-KIT monoclonal antibody (mAb), SR1, is able to slow the growth of three human GIST cell lines in vitro. Importantly, these reductions in cell growth were equivalent between imatinib-resistant and imatinib-sensitive GIST cell lines. Treatment of GIST cell lines with SR1 reduces cell-surface KIT expression, suggesting that mAb-induced KIT down-regulation may be a mechanism by which SR1 inhibits GIST growth. Furthermore, we also show that SR1 treatment enhances phagocytosis of GIST cells by macrophages, indicating that treatment with SR1 may enhance immune cell-mediated tumor clearance. Finally, using two xenotransplantation models of imatinib-sensitive and imatinib-resistant GIST, we demonstrate that SR1 is able to strongly inhibit tumor growth in vivo. These results suggest that treatment with mAbs targeting KIT may represent an alternative, or complementary, approach for treating GIST.

  View details for DOI 10.1073/pnas.1222893110

  View details for Web of Science ID 000315841900062

  View details for PubMedID 23382202

  View details for PubMedCentralID PMC3587280

• Purified Hematopoietic Stem Cell Transplantation: The Next Generation of Blood and Immune Replacement HEMATOLOGY-ONCOLOGY CLINICS OF NORTH AMERICA Czechowicz, A., Weissman, I. L. 2011; 25 (1): 75-?

  Abstract

  Replacement of disease-causing stem cells with healthy ones has been achieved clinically via hematopoietic cell transplantation (HCT) for the last 40 years, as a treatment modality for a variety of cancers and immunodeficiencies with moderate, but increasing, success. This procedure has traditionally included transplantation of mixed hematopoietic populations that include hematopoietic stem cells (HSC) and other cells, such as T cells. This article explores and delineates the potential expansion of this technique to treat a variety of inherited diseases of immune function, the current barriers in HCT and pure HSC transplantation, and the up-and-coming strategies to combat these obstacles.

  View details for DOI 10.1016/j.hoc.2010.11.006

  View details for Web of Science ID 000287333600007

  View details for PubMedID 21236391

• Inhibition of Mac-1 (CD11b/CD18) enhances tumor response to radiation by reducing myeloid cell recruitment PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Ahn, G., Tseng, D., Liao, C., Dorie, M. J., Czechowicz, A., Brown, J. M. 2010; 107 (18): 8363-8368

  Abstract

  Despite recent advances in radiotherapy, loco-regional failures are still the leading cause of death in many cancer patients. We have previously reported that bone marrow-derived CD11b(+) myeloid cells are recruited to tumors grown in irradiated tissues, thereby restoring the vasculature and tumor growth. In this study, we examined whether neutralizing CD11b monoclonal antibodies could inhibit the recruitment of myeloid cells into irradiated tumors and inhibit their regrowth. We observed a significant enhancement of antitumor response to radiation in squamous cell carcinoma xenografts in mice when CD11b antibodies are administered systemically. Histological examination of tumors revealed that CD11b antibodies reduced infiltration of myeloid cells expressing S100A8 and matrix metalloproteinase-9. CD11b antibodies further inhibited bone marrow-derived cell adhesion and transmigration to C166 endothelial cell monolayers and chemotactic stimuli, respectively, to levels comparable to those from CD11b knockout or CD18 hypomorphic mice. Given the clinical availability of humanized CD18 antibodies, we tested two murine tumor models in CD18 hypomorphic or CD11b knockout mice and found that tumors were more sensitive to irradiation when grown in CD18 hypomorphic mice but not in CD11b knockout mice. When CD18 hypomorphism was partially rescued by reconstitution with the wild-type bone marrow, the resistance of the tumors to irradiation was restored. Our study thus supports the rationale of using clinically available Mac-1 (CD11b/CD18) antibodies as an adjuvant therapy to radiotherapy.

  View details for DOI 10.1073/pnas.0911378107

  View details for Web of Science ID 000277310400058

  View details for PubMedID 20404138

  View details for PubMedCentralID PMC2889597

• Purified Hematopoietic Stem Cell Transplantation: The Next Generation of Blood and Immune Replacement IMMUNOLOGY AND ALLERGY CLINICS OF NORTH AMERICA Czechowicz, A., Weissman, I. L. 2010; 30 (2): 159-?

  Abstract

  Replacement of disease-causing stem cells with healthy ones has been achieved clinically via hematopoietic cell transplantation (HCT) for the last 40 years, as a treatment modality for a variety of cancers and immunodeficiencies with moderate, but increasing, success. This procedure has traditionally included transplantation of mixed hematopoietic populations that include hematopoietic stem cells (HSC) and other cells, such as T cells. This article explores and delineates the potential expansion of this technique to treat a variety of inherited diseases of immune function, the current barriers in HCT and pure HSC transplantation, and the up-and-coming strategies to combat these obstacles.

  View details for DOI 10.1016/j.iac.2010.03.003

  View details for Web of Science ID 000279115200003

  View details for PubMedID 20493393

  View details for PubMedCentralID PMC3071240

• Niche recycling through division-independent egress of hematopoietic stem cells JOURNAL OF EXPERIMENTAL MEDICINE Bhattacharya, D., Czechowicz, A., Ooi, A. G., Rossi, D. J., Bryder, D., Weissman, I. L. 2009; 206 (12): 2837-2850

  Abstract

  Hematopoietic stem cells (HSCs) are thought to reside in discrete niches through stable adhesion, yet previous studies have suggested that host HSCs can be replaced by transplanted donor HSCs, even in the absence of cytoreductive conditioning. To explain this apparent paradox, we calculated, through cell surface phenotyping and transplantation of unfractionated blood, that approximately 1-5% of the total pool of HSCs enters into the circulation each day. Bromodeoxyuridine (BrdU) feeding experiments demonstrated that HSCs in the peripheral blood incorporate BrdU at the same rate as do HSCs in the bone marrow, suggesting that egress from the bone marrow to the blood can occur without cell division and can leave behind vacant HSC niches. Consistent with this, repetitive daily transplantations of small numbers of HSCs administered as new niches became available over the course of 7 d led to significantly higher levels of engraftment than did large, single-bolus transplantations of the same total number of HSCs. These data provide insight as to how HSC replacement can occur despite the residence of endogenous HSCs in niches, and suggest therapeutic interventions that capitalize upon physiological HSC egress.

  View details for DOI 10.1084/jem.20090778

  View details for Web of Science ID 000272079300020

  View details for PubMedID 19887396

  View details for PubMedCentralID PMC2806613

• Hematopoietic stem cell quiescence attenuates DNA damage response and permits DNA damage accumulation during aging CELL CYCLE Rossi, D. J., Seita, J., Czechowicz, A., Bhattacharya, D., Bryder, D., Weissman, I. L. 2007; 6 (19): 2371-2376

  Abstract

  The aging of tissue-specific stem and progenitor cells is believed to be central to the pathophysiological conditions arising in aged individuals. While the mechanisms driving stem cell aging are poorly understood, mounting evidence points to age-dependent DNA damage accrual as an important contributing factor. While it has been postulated that DNA damage may deplete stem cell numbers with age, recent studies indicate that murine hematopoietic stem cell (HSC) reserves are in fact maintained despite the accrual of genomic damage with age. Evidence suggests this to be a result of the quiescent (G0) cell cycle status of HSC, which results in an attenuation of checkpoint control and DNA damage responses for repair or apoptosis. When aged stem cells that have acquired damage are called into cycle under conditions of stress or tissue regeneration however, their functional capacity was shown to be severely impaired. These data suggest that age-dependent DNA damage accumulation may underlie the diminished capacity of aged stem cells to mediate a return to homeostasis after acute stress or injury. Moreover, the cytoprotection afforded by stem cell quiescence in stress-free, steady-state conditions suggests a mechanism through which potentially dangerous lesions can accumulate in the stem cell pool with age.

  View details for Web of Science ID 000251085700012

  View details for PubMedID 17700071