RESUMO
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.
Assuntos
Dano ao DNA/imunologia , Transplante de Células-Tronco Hematopoéticas/métodos , Células-Tronco Hematopoéticas/imunologia , Antígenos Comuns de Leucócito/imunologia , Proteínas Inativadoras de Ribossomos Tipo 1/genética , Proteínas Inativadoras de Ribossomos Tipo 1/imunologia , Animais , Anticorpos Monoclonais/genética , Anticorpos Monoclonais/imunologia , Diferenciação Celular/genética , Diferenciação Celular/imunologia , Sobrevivência Celular/genética , Sobrevivência Celular/imunologia , Células Cultivadas , Dano ao DNA/genética , Feminino , Melhoramento Genético/métodos , Fenômenos Imunogenéticos/genética , Imunotoxinas , Camundongos , Camundongos Endogâmicos C57BL , SaporinasRESUMO
BACKGROUND: B43-pokeweed antiviral protein (B43-PAP) is a high-affinity anti-CD19 immunotoxin that is capable of causing apoptotic death in B-lineage leukemic cells with a drug-resistant phenotype. B43-PAP exhibited in vivo antileukemic activity in preclinical studies as well as on a single-agent phase I clinical trial. This pediatric phase I/II study evaluated the toxicity profile and efficacy of B43-PAP immunotoxin in combination with standard induction chemotherapy in children and adolescents with relapsed CD19-positive B-lineage acute lymphoblastic leukemia (B-ALL). Pharmacokinetic profile and immunogenicity of B43-PAP were assessed. EXPERIMENTAL DESIGN: B43-PAP in combination with standard 3 and 4-drug induction chemotherapy was administered on days 9-13 and 21-25 of a 28-day treatment course with vincristine, prednisone, L-asparaginase, daunomycin, and intrathecal methotrexate. Thirty patients with relapsed B-ALL were enrolled on study CCG-0957. RESULTS: Grade III/IV nonhematologic dose-limiting toxicities were encountered in 4 patients evaluable for toxicity and included myalgias, motor dysfunction, pulmonary toxicity, and elevated liver transaminase. Dose-limiting toxicities occurred only with the 4-drug regimen. Fourteen patients achieved a complete remission at the end of induction among the 20 patients evaluable for response. CONCLUSIONS: B43-PAP in combination with standard induction chemotherapy can be safely administered and exhibits clinical antileukemic activity against relapsed B-ALL.
Assuntos
Antígenos CD19/imunologia , Antineoplásicos/uso terapêutico , Linfócitos B/imunologia , Imunotoxinas/imunologia , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Leucemia-Linfoma Linfoblástico de Células Precursoras/imunologia , Proteínas Inativadoras de Ribossomos Tipo 1/imunologia , Adolescente , Anticorpos Monoclonais/imunologia , Criança , Pré-Escolar , Quimioterapia Combinada/métodos , Estudos de Viabilidade , Feminino , Humanos , Quimioterapia de Indução/métodos , MasculinoRESUMO
Many forms of antibody-based targeted therapeutics, including antibody drug conjugates, utilize the internalizing function of the targeting antibody to gain intracellular entry into tumor cells. Ideal antibodies for developing such therapeutics should be capable of both tumor-selective binding and efficient endocytosis. The macropinocytosis pathway is capable of both rapid and bulk endocytosis, and recent studies have demonstrated that it is selectively up-regulated by cancer cells. We hypothesize that receptor-dependent macropinocytosis can be achieved using tumor-targeting antibodies that internalize via the macropinocytosis pathway, improving potency and selectivity of the antibody-based targeted therapeutic. Although phage antibody display libraries have been utilized to find antibodies that bind and internalize to target cells, no methods have been described to screen for antibodies that internalize specifically via macropinocytosis. We hereby describe a novel screening strategy to identify phage antibodies that bind and rapidly enter tumor cells via macropinocytosis. We utilized an automated microscopic imaging-based, High Content Analysis platform to identify novel internalizing phage antibodies that colocalize with macropinocytic markers from antibody libraries that we have generated previously by laser capture microdissection-based selection, which are enriched for internalizing antibodies binding to tumor cells in situ residing in their tissue microenvironment (Ruan, W., Sassoon, A., An, F., Simko, J. P., and Liu, B. (2006) Identification of clinically significant tumor antigens by selecting phage antibody library on tumor cells in situ using laser capture microdissection. Mol. Cell. Proteomics. 5, 2364-2373). Full-length human IgG molecules derived from macropinocytosing phage antibodies retained the ability to internalize via macropinocytosis, validating our screening strategy. The target antigen for a cross-species binding antibody with a highly active macropinocytosis activity was identified as ephrin type-A receptor 2. Antibody-toxin conjugates created using this macropinocytosing IgG were capable of potent and receptor-dependent killing of a panel of EphA2-positive tumor cell lines in vitro. These studies identify novel methods to screen for and validate antibodies capable of receptor-dependent macropinocytosis, allowing further exploration of this highly efficient and tumor-selective internalization pathway for targeted therapy development.
Assuntos
Anticorpos Antineoplásicos/farmacologia , Antígenos de Neoplasias/imunologia , Antineoplásicos/farmacologia , Imunoglobulina G/farmacologia , Biblioteca de Peptídeos , Receptor EphA2/imunologia , Anticorpos Antineoplásicos/imunologia , Anticorpos Antineoplásicos/metabolismo , Afinidade de Anticorpos , Especificidade de Anticorpos , Complexo Antígeno-Anticorpo/genética , Complexo Antígeno-Anticorpo/imunologia , Complexo Antígeno-Anticorpo/metabolismo , Antígenos de Neoplasias/genética , Antígenos de Neoplasias/metabolismo , Antineoplásicos/imunologia , Antineoplásicos/metabolismo , Biomarcadores/metabolismo , Linhagem Celular , Linhagem Celular Tumoral , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Expressão Gênica , Células HEK293 , Ensaios de Triagem em Larga Escala , Humanos , Imunoglobulina G/imunologia , Imunoglobulina G/metabolismo , Imunotoxinas/química , Imunotoxinas/imunologia , Microdissecção e Captura a Laser , Terapia de Alvo Molecular , Pinocitose , Receptor EphA2/genética , Receptor EphA2/metabolismo , Proteínas Inativadoras de Ribossomos Tipo 1/química , Proteínas Inativadoras de Ribossomos Tipo 1/imunologia , SaporinasRESUMO
The epithelial cell adhesion molecule (EpCAM) is expressed by a wide range of human carcinomas, making it an attractive diagnostic and therapeutic target in oncology. Its recent identification on cancer stem cells has raised further interest in its use for tumor targeting and therapy. Here, we present the characterization and therapeutic potential of 3-17I, a novel human EpCAM-targeting monoclonal antibody. Strong reaction of 3-17I was observed in all lung, colon, and breast human tumor biopsies evaluated. By flow cytometry and confocal fluorescence microscopy, we demonstrate that 3-17I specifically targets EpCAM-positive cell lines. We also show evidence for mAb-sequestration in endo-/lysosomes, suggesting internalization of 3-17I by receptor-mediated endocytosis. The ribosomal-inactivating toxin saporin was linked to 3-17I, creating the per se non-toxic immunotoxin 3-17I-saporin, a promising candidate for the drug delivery technology photochemical internalization (PCI). PCI is based on a light-controlled destruction of endolysosomal membranes and subsequent cytosolic release of the sequestered payload upon light exposure. EpCAM-positive human cancer cell lines MCF7 (breast), BxPC-3 (pancreas), WiDr (colon), and the EpCAM-negative COLO320DM (colon), were treated with 3-17I-saporin in combination with the clinically relevant photosensitizer TPCS2a (Amphinex), followed by exposure to light. No cytotoxicity was observed after treatment with 3-17I-saporin without light exposure. However, cell viability, proliferation and colony-forming capacity was strongly reduced in a light-dependent manner after PCI of 3-17I. Our results show that 3-17I is an excellent candidate for diagnosis of EpCAM-positive tumors and for development of clinically relevant antibody-drug conjugates, using PCI for the treatment of localized tumors.
Assuntos
Anticorpos Monoclonais Murinos/farmacologia , Anticorpos Antineoplásicos/farmacologia , Neoplasias da Mama/tratamento farmacológico , Neoplasias do Colo/tratamento farmacológico , Imunotoxinas/farmacologia , Neoplasias Pancreáticas/tratamento farmacológico , Proteínas Inativadoras de Ribossomos Tipo 1/farmacologia , Animais , Anticorpos Monoclonais Murinos/imunologia , Anticorpos Antineoplásicos/imunologia , Neoplasias da Mama/imunologia , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Neoplasias do Colo/imunologia , Neoplasias do Colo/patologia , Sistemas de Liberação de Medicamentos/métodos , Feminino , Humanos , Imunotoxinas/imunologia , Neoplasias Pancreáticas/imunologia , Neoplasias Pancreáticas/patologia , Fotoquímica/métodos , Proteínas Inativadoras de Ribossomos Tipo 1/imunologia , SaporinasRESUMO
Targeted endocytic uptake is a first step toward tissue-specific cytoplasmic macromolecular delivery; however, inefficient escape from the endolysosomal compartment makes this generally impractical at present. We report here a targeted cytolysin approach that dramatically potentiates endosomal release of an independently targeted potent gelonin immunotoxin. Fibronectin domains engineered for affinity to EGF receptor or carcinoembryonic antigen were fused to the plant toxin gelonin or bacterial pore-forming cytolysins. These fusion proteins display synergistic activity in both antigen-specific cytotoxicity in vitro, enhancing potency by several orders of magnitude, and in tumor growth inhibition in vivo. In addition, the number of internalized gelonin molecules required to induce apoptosis is reduced from approximately 5 × 10(6) to less than 10(3). Targeted potentiation shows promise for enhancing cytoplasmic delivery of other macromolecular payloads such as DNA, siRNA, and miRNA.
Assuntos
Antígeno Carcinoembrionário/imunologia , Citotoxinas/imunologia , Endossomos/metabolismo , Receptores ErbB/imunologia , Fibronectinas/metabolismo , Imunotoxinas/imunologia , Proteínas Inativadoras de Ribossomos Tipo 1/administração & dosagem , Proteínas Inativadoras de Ribossomos Tipo 1/imunologia , Animais , Apoptose/efeitos dos fármacos , Apoptose/genética , Linhagem Celular Tumoral , Citoplasma/imunologia , Citotoxinas/farmacologia , Sinergismo Farmacológico , Endossomos/imunologia , Fibronectinas/imunologia , Humanos , Imunotoxinas/farmacologia , Camundongos , Terapia de Alvo Molecular , Especificidade de Órgãos , Proteínas Inativadoras de Ribossomos Tipo 1/farmacologiaRESUMO
We conducted a phase 1 study of an anti-CD33 immunotoxin, humanized monoclonal antibody M195 conjugated to recombinant gelonin (HUM-195/rGEL), in patients with relapsed, refractory myeloid leukemias. Twenty-eight patients received the construct intravenously at four dose levels (12, 18, 28 and 40 mg/m(2) per course) in a "3+3" study design. The dose-limiting toxicity was infusion-related allergic reaction including hypoxia and hypotension. The 28 mg/m(2) total dose was considered the maximally tolerated dose. Four patients developed a reduction in peripheral blood blasts of at least 50%. Three patients treated with the 10, 12 and 28 mg/m(2) doses showed a 38-50% reduction in bone marrow blasts. There was normalization of platelets in one patient treated with 40 mg/m(2). Pharmacokinetic analysis demonstrated that the highest blood levels achieved were 200-300 ng/mL which cleared with a half-life of â¼20 hours. Antigenicity was low with one patient at the 12 mg/m(2) dose and one patient at the 18 mg/m(2) dose (2/23, <10%) developing antibodies to the recombinant gelonin component after 28 days. We concluded that HUM-195/rGel can be safely administered in a multi-dose cycle to patients with advanced myeloid malignancies and warrants further investigation.
Assuntos
Anticorpos Monoclonais/uso terapêutico , Antineoplásicos/uso terapêutico , Imunotoxinas/uso terapêutico , Leucemia Mieloide/tratamento farmacológico , Leucemia Mieloide/patologia , Proteínas Inativadoras de Ribossomos Tipo 1/uso terapêutico , Adulto , Idoso , Idoso de 80 Anos ou mais , Anticorpos Monoclonais/imunologia , Anticorpos Monoclonais/farmacologia , Antineoplásicos/farmacologia , Feminino , Humanos , Imunoglobulina G/sangue , Imunoglobulina G/imunologia , Imunotoxinas/imunologia , Imunotoxinas/farmacologia , Leucemia Mieloide/imunologia , Masculino , Pessoa de Meia-Idade , Proteínas Inativadoras de Ribossomos Tipo 1/imunologia , Proteínas Inativadoras de Ribossomos Tipo 1/farmacologia , Resultado do TratamentoRESUMO
Therapeutic agents capable of targeting tumor cells present as established tumors and micrometastases have already demonstrated their potential in clinical trials. Immunotoxins targeting hematological malignancies and solid tumors have additionally demonstrated excellent clinical activity. This review focuses on our design and characterization studies of constructs composed of recombinant gelonin toxin fused to either growth factors or single-chain antibodies targeting solid tumor cells, tumor vasculature or hematological malignancies. These agents demonstrate cytotoxicity at nanomolar or sub-nanomolar levels. All of these constructs display impressive selectivity and specificity for antigen-bearing target cells in vitro and in vivo and are excellent clinical trial candidates.
Assuntos
Membrana Corioalantoide/irrigação sanguínea , Fragmentos de Imunoglobulinas/imunologia , Imunotoxinas/imunologia , Peptídeos e Proteínas de Sinalização Intercelular/imunologia , Neoplasias/tratamento farmacológico , Neovascularização Patológica , Proteínas Inativadoras de Ribossomos Tipo 1/imunologia , Anticorpos de Cadeia Única/imunologia , Animais , Antineoplásicos Fitogênicos/imunologia , Antineoplásicos Fitogênicos/farmacologia , Linfócitos B/efeitos dos fármacos , Linfócitos B/imunologia , Linfócitos B/patologia , Embrião de Galinha , Membrana Corioalantoide/efeitos dos fármacos , Membrana Corioalantoide/metabolismo , Epitopos , Humanos , Fragmentos de Imunoglobulinas/genética , Fragmentos de Imunoglobulinas/farmacologia , Imunotoxinas/genética , Imunotoxinas/farmacologia , Peptídeos e Proteínas de Sinalização Intercelular/genética , Peptídeos e Proteínas de Sinalização Intercelular/farmacologia , Camundongos , Camundongos Nus , Terapia de Alvo Molecular/métodos , Neoplasias/imunologia , Neoplasias/patologia , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/imunologia , Proteínas Recombinantes de Fusão/farmacologia , Proteínas Inativadoras de Ribossomos Tipo 1/genética , Proteínas Inativadoras de Ribossomos Tipo 1/farmacologia , Anticorpos de Cadeia Única/genética , Anticorpos de Cadeia Única/farmacologia , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Recombinant immunotoxins, consisting of single-chain variable fragments (scFv) genetically fused to polypeptide toxins, represent potentially effective candidates for cancer therapeutics. We evaluated the affinity of various anti-Her2/neu scFv fused to recombinant gelonin (rGel) and its effect on antitumor efficacy and off-target toxicity. A series of rGel-based immunotoxins were created from the human anti-Her2/neu scFv C6.5 and various affinity mutants (designated ML3-9, MH3-B1, and B1D3) with affinities ranging from 10(-8) to 10(-11) mol/L. Against Her2/neu-overexpressing tumor cells, immunotoxins with increasing affinity displayed improved internalization and enhanced autophagic cytotoxicity. Targeting indices were highest for the highest affinity B1D3/rGel construct. However, the addition of free Her2/neu extracellular domain (ECD) significantly reduced the cytotoxicity of B1D3/rGel because of immune complex formation. In contrast, ECD addition had little impact on the lower affinity constructs in vitro. In vivo studies against established BT474 M1 xenografts showed growth suppression by all immunotoxins. Surprisingly, therapy with the B1D3-rGel induced significant liver toxicity because of immune complex formation with shed Her2/neu antigen in circulation. The MH3-B1/rGel construct with intermediate affinity showed effective tumor growth inhibition without inducing hepatotoxicity or complex formation. These findings show that while high-affinity constructs can be potent antitumor agents, they may also be associated with mistargeting through the facile formation of complexes with soluble antigen leading to significant off-target toxicity. Constructs composed of intermediate-affinity antibodies are also potent agents that are more resistant to immune complex formation. Therefore, affinity is an exceptionally important consideration when evaluating the design and efficacy of targeted therapeutics.
Assuntos
Imunotoxinas/farmacologia , Receptor ErbB-2/imunologia , Proteínas Inativadoras de Ribossomos Tipo 1/farmacologia , Anticorpos de Cadeia Única/farmacologia , Animais , Afinidade de Anticorpos , Antineoplásicos/imunologia , Antineoplásicos/farmacologia , Humanos , Imunotoxinas/química , Imunotoxinas/imunologia , Camundongos , Camundongos Nus , Neoplasias/imunologia , Proteínas Inativadoras de Ribossomos Tipo 1/imunologia , Anticorpos de Cadeia Única/imunologia , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Ribosome-inactivating proteins (RIPs) are a family of plant toxins that permanently damage ribosomes and possibly other cellular substrates, thus causing cell death. RIPs are mostly divided in two types: Type 1 RIPs that are single-chain enzymatic proteins, and type 2 RIPs that consist of an active A chain (similar to a type 1 RIP) linked to a B chain with lectin properties. RIP-containing conjugates have been used in many experimental strategies against cancer cells, often showing great efficacy in clinical trials. Saporin-S6, a type 1 RIP extracted from Saponaria officinalis L. seeds, has been extensively utilized to construct anti-cancer conjugates because of its high enzymatic activity, stability and resistance to conjugation procedures, resulting in the efficient killing of target cells. This review summarizes saporin-S6-containing conjugates and their application in cancer therapy, considering in-vitro and in-vivo studies both in animal models and in clinical trials. The review is structured on the basis of the targeting of hematological versus solid tumors and on the antigen recognized on the cell surface.
Assuntos
Anticorpos Monoclonais/uso terapêutico , Antineoplásicos/uso terapêutico , Imunotoxinas/uso terapêutico , Neoplasias/tratamento farmacológico , Proteínas Inativadoras de Ribossomos Tipo 1/química , Animais , Anticorpos Monoclonais/química , Anticorpos Monoclonais/farmacologia , Antígenos de Neoplasias/sangue , Antineoplásicos/química , Antineoplásicos/farmacologia , Linhagem Celular Tumoral , Ensaios Clínicos como Assunto , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Imunoconjugados/química , Imunoconjugados/farmacologia , Imunoconjugados/uso terapêutico , Imunotoxinas/química , Imunotoxinas/farmacologia , Neoplasias/imunologia , Proteínas Inativadoras de Ribossomos Tipo 1/imunologia , Proteínas Inativadoras de Ribossomos Tipo 1/isolamento & purificação , Saponaria/química , Saporinas , Sementes/químicaRESUMO
Gelonin-based immunotoxins vary widely in their cytotoxic potency as a function of antigen density, target cell internalization and trafficking kinetics, and conjugate properties. We have synthesized novel gelonin immunotoxins using two different binding scaffold types (single-chain antibody variable fragments and fibronectin domains) targeting two different tumor antigens (carcinoembryonic antigen and EGF receptor). Constructs were characterized using an antigen-negative cell line (HT-1080), cell lines positive for each antigen (HT-1080(CEA) for carcinoembryonic antigen and A431 for EGF receptor), and a cell line positive for both antigens (HT-29). Immunotoxins exhibited K(d) values between 8 and 15 nm and showed 20-2000-fold enhanced cytotoxicity compared with gelonin (IC(50) â¼ 0.25-30 nM versus 500 nM). Using quantitative fluorescence flow cytometry, we measured internalization of gelonin (via pinocytosis) and gelonin-based immunotoxins (via antigen-dependent, receptor-mediated endocytosis). Results were matched with cytotoxicity measurements made at equivalent concentration and exposures. Unexpectedly, when matched internalization and cytotoxicity data were combined, a conserved internalized cytotoxicity curve was generated that was common across experimental conditions. Considerable variations in antigen expression, trafficking kinetics, extracellular immunotoxin concentration, and exposure time were all found to collapse to a single potency curve on the basis of internalized immunotoxin. Fifty percent cytotoxicity occurred when â¼ 5 × 10(6) toxin molecules were internalized regardless of the mechanism of uptake. Cytotoxicity observed at a threshold internalization was consistent with the hypothesis that endosomal escape is a common, highly inefficient, rate-limiting step following internalization by any means tested. Methods designed to enhance endosomal escape might be utilized to improve the potency of gelonin-based immunotoxins.
Assuntos
Fibronectinas/farmacologia , Imunotoxinas/farmacologia , Proteínas Recombinantes de Fusão/farmacologia , Proteínas Inativadoras de Ribossomos Tipo 1/farmacologia , Anticorpos de Cadeia Única/farmacologia , Antígeno Carcinoembrionário/imunologia , Linhagem Celular Tumoral , Ensaios de Seleção de Medicamentos Antitumorais/métodos , Receptores ErbB/imunologia , Fibronectinas/genética , Fibronectinas/imunologia , Humanos , Imunotoxinas/genética , Imunotoxinas/imunologia , Estrutura Terciária de Proteína , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/imunologia , Proteínas Inativadoras de Ribossomos Tipo 1/genética , Proteínas Inativadoras de Ribossomos Tipo 1/imunologia , Anticorpos de Cadeia Única/genética , Anticorpos de Cadeia Única/imunologiaRESUMO
BACKGROUND: Prostate-specific membrane antigen (PSMA) provides an attractive target for monoclonal antibody targeted therapies in the treatment of prostate cancer (PC). In this study, we generated an immunotoxin by linking a humanized anti-PSMA monoclonal antibody (hJ591) to the ribosome-inactivating protein toxin saporin. The hJ591-saporin immunoconjugate was evaluated for antitumor activity against PC cells. METHODS: PSMA-positive cell lines, LNCaP and CWR22Rv1 and a PSMA-negative cell line, PC-3, were used in these experiments. The hJ591 was biotinylated and mixed with streptavidin-saporin (SAZAP). The binding ability of hJ591-SAZAP and the extent of internalization into the cells were tested. The viability of cells treated with hJ591-SAZAP was also examined and the apoptotic cells were measured. Lastly, the anticancer effect of hJ591-SAZAP was investigated in vivo. RESULTS: The binding ability of hJ591-SAZAP to PSMA was equivalent to that of unconjugated J591. Internalization of hJ591-SAZAP was clearly detected in PSMA-positive, but not in PSMA-negative cell lines. IC(50) of hJ591-SAZAP was 0.14 nM, 1.99 nM, and more than 100 nM in LNCaP, CWR22Rv1, and PC-3 cells, respectively. After 72 hr of hJ591-SAZAP treatment, the percentage of apoptotic cells was 60.29% and 40.73% in LNCaP and CWR22Rv1 cells, respectively, compared to 4.70% in PC-3 cells. The hJ591-SAZAP also had anticancer activity in a LNCaP xenograft model. CONCLUSIONS: Our findings show that hJ591-SAZAP conjugate has potent and selective antitumor effects on PSMA-positive PC cells in vitro and in vivo. This study supports development of PSMA antibody-toxin conjugates for therapy of PC.