RESUMEN
BACKGROUND: Cancer immunotherapy approaches that elicit immune cell responses, including T and NK cells, have revolutionized the field of oncology. However, immunosuppressive mechanisms restrain immune cell activation within solid tumors so additional strategies to augment activity are required. METHODS: We identified the co-stimulatory receptor NKG2D as a target based on its expression on a large proportion of CD8+ tumor infiltrating lymphocytes (TILs) from breast cancer patient samples. Human and murine surrogate NKG2D co-stimulatory receptor-bispecifics (CRB) that bind NKG2D on NK and CD8+ T cells as well as HER2 on breast cancer cells (HER2-CRB) were developed as a proof of concept for targeting this signaling axis in vitro and in vivo. RESULTS: HER2-CRB enhanced NK cell activation and cytokine production when co-cultured with HER2 expressing breast cancer cell lines. HER2-CRB when combined with a T cell-dependent-bispecific (TDB) antibody that synthetically activates T cells by crosslinking CD3 to HER2 (HER2-TDB), enhanced T cell cytotoxicity, cytokine production and in vivo antitumor activity. A mouse surrogate HER2-CRB (mHER2-CRB) improved in vivo efficacy of HER2-TDB and augmented NK as well as T cell activation, cytokine production and effector CD8+ T cell differentiation. CONCLUSION: We demonstrate that targeting NKG2D with bispecific antibodies (BsAbs) is an effective approach to augment NK and CD8+ T cell antitumor immune responses. Given the large number of ongoing clinical trials leveraging NK and T cells for cancer immunotherapy, NKG2D-bispecifics have broad combinatorial potential.
Asunto(s)
Neoplasias de la Mama , Linfocitos T CD8-positivos , Células Asesinas Naturales , Subfamilia K de Receptores Similares a Lectina de Células NK , Humanos , Animales , Subfamilia K de Receptores Similares a Lectina de Células NK/metabolismo , Subfamilia K de Receptores Similares a Lectina de Células NK/inmunología , Ratones , Linfocitos T CD8-positivos/inmunología , Células Asesinas Naturales/inmunología , Femenino , Neoplasias de la Mama/inmunología , Neoplasias de la Mama/terapia , Receptor ErbB-2/inmunología , Línea Celular Tumoral , Inmunoterapia/métodos , Activación de Linfocitos/inmunología , Linfocitos Infiltrantes de Tumor/inmunología , Linfocitos Infiltrantes de Tumor/metabolismoRESUMEN
Disulfide-linked bioconjugates allow the delivery of pharmacologically active or other cargo to specific tissues in a redox-sensitive fashion. However, an understanding of the kinetics, subcellular distribution, and mechanism of disulfide cleavage in such bioconjugates is generally lacking. Here, we report a modular disulfide-linked TAMRA-BODIPY based FRET probe that can be readily synthesized, modified, and conjugated to a cysteine-containing biomolecule to enable real-time monitoring of disulfide cleavage during receptor-mediated endocytosis in cells. We demonstrate the utility of this probe to study disulfide reduction during HER2 receptor-mediated uptake of a Cys-engineered anti-HER2 THIOMAB antibody. We found that introduction of positive, but not negative, charges in the probe improved retention of the BODIPY catabolite. This permitted the observation of significant disulfide cleavage in endosomes or lysosomes on par with proteolytic cleavage of a similarly charged valine-citrulline peptide-based probe. In general, the FRET probe we describe should enable real-time cellular monitoring of disulfide cleavage in other targeted delivery systems for mechanistic or diagnostic applications. Furthermore, modifications to the released BODIPY moiety permit evaluation of physicochemical properties that govern lysosomal egress or retention, which may have implications for the development of next-generation antibody-drug conjugates.
Asunto(s)
Cisteína/química , Disulfuros/química , Transferencia Resonante de Energía de Fluorescencia , Colorantes Fluorescentes/química , Animales , Compuestos de Boro , Monitoreo de Drogas/métodos , Endocitosis , Endosomas/metabolismo , Transferencia Resonante de Energía de Fluorescencia/tendencias , Humanos , Inmunoconjugados , Lisosomas/metabolismo , Receptor ErbB-2/inmunología , RodaminasRESUMEN
This work discloses the first examples of antibody-drug conjugates (ADCs) that are constructed from linker-drugs bearing dimeric seco-CBI payloads (duocarmycin analogs). Several homogeneous, CD22-targeting THIOMAB antibody-drug conjugates (TDCs) containing the dimeric seco-CBI entities are shown to be highly efficacious in the WSU-DLCL2 and BJAB mouse xenograft models. Surprisingly, the seco-CBI-containing conjugates are also observed to undergo significant biotransformation in vivo in mice, rats, and monkeys and thereby form 1:1 adducts with the Alpha-1-Microglobulin (A1M) plasma protein from these species. Variation of both the payload mAb attachment site and length of the linker-drug is shown to alter the rates of adduct formation. Subsequent experiments demonstrated that adduct formation attenuates the in vitro antiproliferation activity of the affected seco-CBI-dimer TDCs, but does not significantly impact the in vivo efficacy of the conjugates. In vitro assays employing phosphatase-treated whole blood suggest that A1M adduct formation is likely to occur if the seco-CBI-dimer TDCs are administered to humans. Importantly, protein adduct formation leads to the underestimation of total antibody (Tab) concentrations using an ELISA assay but does not affect Tab values determined via an orthogonal LC-MS/MS method. Several recommendations regarding bioanalysis of future in vivo studies involving related seco-CBI-containing ADCs are provided based on these collective findings.
Asunto(s)
alfa-Globulinas/química , Antineoplásicos/farmacología , Inmunoconjugados/farmacología , Animales , Antineoplásicos/química , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Dimerización , Haplorrinos , Humanos , Inmunoconjugados/química , Ratones , Ratas , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Carfilzomib (CFZ) is a proteasome inhibitor used for oncology indications including treating multiple myeloma. CFZ is a potent cytotoxic agent with an IC50 value in the nanomolar range in various cancer cell lines and was considered as a potential payload for antibody drug conjugates (ADCs); however, the conjugated CFZ to anti-CD22 or anti-HER2 antibody totally abolishes the in vitro potency. This was a surprise since with other payloads such as monomethyl auristatin E (MMAE), where potent antiproliferation efficacy was retained as MMAE alone or as a payload in an ADC. Further investigations were conducted using CFZ alone, CFZ with a linker, and CFZ-ADC with tissue matrices including lysosomal enzymes. With CFZ linked to the ADC, cathepsin B (a lysosomal enzyme) was efficient in liberating CFZ from the ADC by cleavage of the valine-citrulline linker. At the same time, the liberated CFZ in the lysosome was inactivated due to further metabolism by lysosomal enzymes. The products from epoxide and amide hydrolysis were identified from these incubations. These results suggested that the CFZ-ADC upon uptake and internalization specifically delivers CFZ payload to the lysosomes, where CFZ was inactivated. On the other hand, CFZ by itself is not as vulnerable and could reach its target. Therefore, lysosomal stability is an important criterion in the selection of a payload for making the next generation of potent ADC therapeutics.
Asunto(s)
Anticuerpos Monoclonales/farmacocinética , Antineoplásicos/farmacocinética , Inmunoconjugados/farmacocinética , Lisosomas/enzimología , Oligopéptidos/farmacocinética , Anticuerpos Monoclonales/administración & dosificación , Anticuerpos Monoclonales/química , Antineoplásicos/administración & dosificación , Antineoplásicos/química , Catepsina B/química , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Ensayos de Selección de Medicamentos Antitumorales , Estudios de Factibilidad , Humanos , Inmunoconjugados/administración & dosificación , Inmunoconjugados/química , Neoplasias/tratamiento farmacológico , Neoplasias/metabolismo , Oligopéptidos/administración & dosificación , Oligopéptidos/química , Receptor ErbB-2/antagonistas & inhibidores , Lectina 2 Similar a Ig de Unión al Ácido Siálico/antagonistas & inhibidoresRESUMEN
THIOMAB antibody technology utilizes cysteine residues engineered onto an antibody to allow for site-specific conjugation. The technology has enabled the exploration of different attachment sites on the antibody in combination with small molecules, peptides, or proteins to yield antibody conjugates with unique properties. As reported previously ( Shen , B. Q. , et al. ( 2012 ) Nat. Biotechnol. 30 , 184 - 189 ; Pillow , T. H. , et al. ( 2017 ) Chem. Sci. 8 , 366 - 370 ), the specific location of the site of conjugation on an antibody can impact the stability of the linkage to the engineered cysteine for both thio-succinimide and disulfide bonds. High stability of the linkage is usually desired to maximize the delivery of the cargo to the intended target. In the current study, cysteines were individually substituted into every position of the anti-HER2 antibody (trastuzumab), and the stabilities of drug conjugations at those sites were evaluated. We screened a total of 648 THIOMAB antibody-drug conjugates, each generated from a trastuzamab prepared by sequentially mutating non-cysteine amino acids in the light and heavy chains to cysteine. Each THIOMAB antibody variant was conjugated to either maleimidocaproyl-valine-citrulline-p-aminobenzyloxycarbonyl-monomethyl auristatin E (MC-vc-PAB-MMAE) or pyridyl disulfide monomethyl auristatin E (PDS-MMAE) using a high-throughput, on-bead conjugation and purification method. Greater than 50% of the THIOMAB antibody variants were successfully conjugated to both MMAE derivatives with a drug to antibody ratio (DAR) of >0.5 and <50% aggregation. The relative in vitro plasma stabilities for approximately 750 conjugates were assessed using enzyme-linked immunosorbent assays, and stable sites were confirmed with affinity-capture LC/MS-based detection methods. Highly stable conjugation sites for the two types of MMAE derivatives were identified on both the heavy and light chains. Although the stabilities of maleimide conjugates were shown to be greater than those of the disulfide conjugates, many sites were identified that were stable for both. Furthermore, in vitro stabilities of selected stable sites translated across different cytotoxic payloads and different target antibodies as well as to in vivo stability.
Asunto(s)
Antineoplásicos Inmunológicos/química , Cisteína/química , Disulfuros/química , Inmunoconjugados/química , Maleimidas/química , Trastuzumab/química , Animales , Antineoplásicos Inmunológicos/sangre , Cisteína/sangre , Cisteína/genética , Disulfuros/sangre , Estabilidad de Medicamentos , Ensayos Analíticos de Alto Rendimiento , Humanos , Inmunoconjugados/sangre , Maleimidas/sangre , Modelos Moleculares , Mutagénesis Sitio-Dirigida , Oligopéptidos/sangre , Oligopéptidos/química , Agregado de Proteínas , Estabilidad Proteica , Ratas , Trastuzumab/sangre , Trastuzumab/genéticaRESUMEN
The valine-citrulline (Val-Cit) dipeptide and p-aminobenzyl (PAB) spacer have been commonly used as a cleavable self-immolating linker in ADC design including in the clinically approved ADC, brentuximab vedotin (Adcetris). When the same linker was used to connect to the phenol of the cyclopropabenzindolone (CBI) (P1), the resulting ADC1 showed loss of potency in CD22 target-expressing cancer cell lines (e.g., BJAB, WSU-DLCL2). In comparison, the conjugate (ADC2) of a cyclopropapyrroloindolone (CPI) (P2) was potent despite the two corresponding free drugs having similar picomolar cell-killing activity. Although the corresponding spirocyclization products of P1 and P2, responsible for DNA alkylation, are a prominent component in buffer, the linker immolation was slow when the PAB was connected as an ether (PABE) to the phenol in P1 compared to that in P2. Additional immolation studies with two other PABE-linked substituted phenol compounds showed that electron-withdrawing groups accelerated the immolation to release an acidic phenol-containing payload (to delocalize the negative charge on the anticipated anionic phenol oxygen during immolation). In contrast, efficient immolation of LD4 did not result in an active ADC4 because the payload (P4) had a low potency to kill cells. In addition, nonimmolation of LD5 did not affect the cell-killing potency of its ADC5 since immolation is not required for DNA alkylation by the center-linked pyrrolobenzodiazepine. Therefore, careful evaluation needs to be conducted when the Val-Cit-PAB linker is used to connect antibodies to a phenol-containing drug as the linker immolation, as well as payload potency and stability, affects the cell-killing activity of an ADC.
Asunto(s)
Supervivencia Celular/efectos de los fármacos , Inmunoconjugados/química , Inmunoconjugados/farmacología , Fenol/química , Fenol/farmacología , Antineoplásicos Inmunológicos/química , Antineoplásicos Inmunológicos/farmacología , Brentuximab Vedotina , Línea Celular Tumoral , Ciclopropanos/química , Ciclopropanos/farmacología , Humanos , Neoplasias/tratamiento farmacológicoRESUMEN
Previous investigations on antibody-drug conjugate (ADC) stability have focused on drug release by linker-deconjugation due to the relatively stable payloads such as maytansines. Recent development of ADCs has been focused on exploring technologies to produce homogeneous ADCs and new classes of payloads to expand the mechanisms of action of the delivered drugs. Certain new ADC payloads could undergo metabolism in circulation while attached to antibodies and thus affect ADC stability, pharmacokinetics, and efficacy and toxicity profiles. Herein, we investigate payload stability specifically and seek general guidelines to address payload metabolism and therefore increase the overall ADC stability. Investigation was performed on various payloads with different functionalities (e.g., PNU-159682 analog, tubulysin, cryptophycin, and taxoid) using different conjugation sites (HC-A118C, LC-K149C, and HC-A140C) on THIOMAB antibodies. We were able to reduce metabolism and inactivation of a broad range of payloads of THIOMAB antibody-drug conjugates by employing optimal conjugation sites (LC-K149C and HC-A140C). Additionally, further payload stability was achieved by optimizing the linkers. Coupling relatively stable sites with optimized linkers provided optimal stability and reduction of payloads metabolism in circulation in vivo.
Asunto(s)
Anticuerpos/química , Inmunoconjugados/química , Factores Inmunológicos/química , Preparaciones Farmacéuticas/química , Antígenos/inmunología , Sitios de Unión , Estabilidad de Medicamentos , Humanos , Inmunoconjugados/administración & dosificación , Inmunoconjugados/farmacocinética , Factores Inmunológicos/administración & dosificación , Factores Inmunológicos/farmacocinéticaRESUMEN
A novel strategy to attach indole-containing payloads to antibodies through a carbamate moiety and a self-immolating, disulfide-based linker is described. This new strategy was employed to connect a selective estrogen receptor down-regulator (SERD) to various antibodies in a site-selective manner. The resulting conjugates displayed potent, antigen-dependent down-regulation of estrogen receptor levels in MCF7-neo/HER2 and MCF7-hB7H4 cells. They also exhibited similar antigen-dependent modulation of the estrogen receptor in tumors when administered intravenously to mice bearing MCF7-neo/HER2 tumor xenografts. The indole-carbamate moiety present in the new linker was stable in whole blood from various species and also exhibited good inâ vivo stability properties in mice.
Asunto(s)
Indoles/química , Animales , Anticuerpos Monoclonales/química , Línea Celular Tumoral , Humanos , Inmunoconjugados/administración & dosificación , Células MCF-7 , RatonesRESUMEN
A number of cytotoxic pyrrolobenzodiazepine (PBD) monomers containing various disulfide-based prodrugs were evaluated for their ability to undergo activation (disulfide cleavage) in vitro in the presence of either glutathione (GSH) or cysteine (Cys). A good correlation was observed between in vitro GSH stability and in vitro cytotoxicity toward tumor cell lines. The prodrug-containing compounds were typically more potent against cells with relatively high intracellular GSH levels (e.g., KPL-4 cells). Several antibody-drug conjugates (ADCs) were subsequently constructed from PBD dimers that incorporated selected disulfide-based prodrugs. Such HER2 conjugates exhibited potent antiproliferation activity against KPL-4 cells in vitro in an antigen-dependent manner. However, the disulfide prodrugs contained in the majority of such entities were surprisingly unstable toward whole blood from various species. One HER2-targeting conjugate that contained a thiophenol-derived disulfide prodrug was an exception to this stability trend. It exhibited potent activity in a KPL-4 in vivo efficacy model that was approximately three-fold weaker than that displayed by the corresponding parent ADC. The same prodrug-containing conjugate demonstrated a three-fold improvement in mouse tolerability properties in vivo relative to the parent ADC, which did not contain the prodrug.
Asunto(s)
Benzodiazepinas/química , Disulfuros/química , Inmunoconjugados/química , Profármacos/química , Pirroles/química , Línea Celular Tumoral , Cisteína/metabolismo , Glutatión/metabolismo , Humanos , Inmunoconjugados/metabolismo , Estructura MolecularRESUMEN
Conjugation of small molecule payloads to cysteine residues on proteins via a disulfide bond represents an attractive strategy to generate redox-sensitive bioconjugates, which have value as potential diagnostic reagents or therapeutics. Advancement of such "direct-disulfide" bioconjugates to the clinic necessitates chemical methods to form disulfide connections efficiently, without byproducts. The disulfide connection must also be resistant to premature cleavage by thiols prior to arrival at the targeted tissue. We show here that commonly employed methods to generate direct disulfide-linked bioconjugates are inadequate for addressing these challenges. We describe our efforts to optimize direct-disulfide conjugation chemistry, focusing on the generation of conjugates between cytotoxic payloads and cysteine-engineered antibodies (i.e., THIOMAB antibody-drug conjugates, or TDCs). This work culminates in the development of novel, high-yielding conjugation chemistry for creating direct payload disulfide connections to any of several Cys mutation sites in THIOMAB antibodies or to Cys sites in other biomolecules (e.g., human serum albumin and cell-penetrating peptides). We conclude by demonstrating that hindered direct disulfide TDCs with two methyl groups adjacent to the disulfide, which have heretofore not been described for any bioconjugate, are more stable and more efficacious in mouse tumor xenograft studies than less hindered analogs.
Asunto(s)
Cisteína , Disulfuros/química , Inmunoconjugados/química , Péptidos/química , Ingeniería de Proteínas , Animales , Línea Celular Tumoral , Transformación Celular Neoplásica , Humanos , Inmunoconjugados/genética , RatonesRESUMEN
Antibody-drug conjugates (ADCs) are target-specific anticancer agents consisting of cytotoxic drugs covalently linked to a monoclonal antibody. The number of ADCs in the clinic is growing, and therefore thorough characterization of the quantitative assays used to measure ADC concentrations in support of pharmacokinetic, efficacy, and safety studies is of increasing importance. Cytotoxic drugs such as the tubulin polymerization inhibiting auristatin, monomethyl auristatin E, have been conjugated to antibodies via cleavable linkers (MC-vc-PAB) through internal cysteines. This results in a heterogeneous mixture of antibody species with drug-to-antibody ratios (DAR) ranging from 0 to 8. In order to characterize the assays used to quantitate total MC-vc-PAB-MMAE ADCs (conjugated and unconjugated antibody), we used purified fractions with defined DARs from 6 therapeutic antibodies to evaluate different assay formats and reagents. Our investigations revealed that for quantitation of total antibody, including all unconjugated and conjugated antibody species, sandwich ELISA formats did not always allow for recovery of all purified DAR fractions (DAR 0-8) to within ±20% of the expected values at the reagent concentrations tested. In evaluating alternative approaches, we found that the recovery of DAR fractions with semihomogeneous assay (SHA) formats, in which sample, capture, and detection reagents are preincubated in solution, were less affected by the antibody's MMAE drug load as compared to traditional stepwise sandwich ELISAs. Thus, choosing the optimal assay format and reagents for total antibody assays is valuable for developing accurate quantitative assays.
Asunto(s)
Antineoplásicos/farmacocinética , Inmunotoxinas/farmacocinética , Oligopéptidos/farmacocinética , Moduladores de Tubulina/farmacocinética , Animales , Antineoplásicos/química , Ensayo de Inmunoadsorción Enzimática , Inmunotoxinas/química , Ratones , Ratones SCID , Oligopéptidos/química , Moduladores de Tubulina/químicaRESUMEN
The antibody-drug conjugate (ADC) is a well-validated modality for the cell-specific delivery of small molecules with impact expanding rapidly beyond their originally-intended purpose of treating cancer. However, antibody-mediated delivery (AMD) remains inefficient, limiting its applicability to targeting highly potent payloads to cells with high antigen expression. Maximizing the number of payloads delivered per antibody is one key way in which delivery efficiency can be improved, although this has been challenging to carry out; with few exceptions, increasing the drug-to-antibody ratio (DAR) above â¼4 typically destroys the biophysical properties and in vivo efficacy for ADCs. Herein, we describe the development of a novel bioconjugation platform combining cysteine-engineered (THIOMAB) antibodies and recombinant XTEN polypeptides for the unprecedented generation of homogeneous, stable "TXCs" with DAR of up to 18. Across three different bioactive payloads, we demonstrated improved AMD to tumors and Staphylococcus aureus bacteria for high-DAR TXCs relative to conventional low-DAR ADCs.
RESUMEN
Antibody-drug conjugates (ADCs) are designed to combine the exquisite specificity of antibodies to target tumor antigens with the cytotoxic potency of chemotherapeutic drugs. In addition to the general chemical stability of the linker, a thorough understanding of the relationship between ADC composition and biological disposition is necessary to ensure that the therapeutic window is not compromised by altered pharmacokinetics (PK), tissue distribution, and/or potential organ toxicity. The six-transmembrane epithelial antigen of prostate 1 (STEAP1) is being pursued as a tumor antigen target. To assess the role of ADC composition in PK, we evaluated plasma and tissue PK profiles in rats, following a single dose, of a humanized anti-STEAP1 IgG1 antibody, a thio-anti-STEAP1 (ThioMab) variant, and two corresponding thioether-linked monomethylauristatin E (MMAE) drug conjugates modified through interchain disulfide cysteine residues (ADC) and engineered cysteines (TDC), respectively. Plasma PK of total antibody measured by enzyme-linked immunosorbent assay (ELISA) revealed â¼45% faster clearance for the ADC relative to the parent antibody, but no apparent difference in clearance between the TDC and unconjugated parent ThioMab. Total antibody clearances of the two unconjugated antibodies were similar, suggesting minimal effects on PK from cysteine mutation. An ELISA specific for MMAE-conjugated antibody indicated that the ADC cleared more rapidly than the TDC, but total antibody ELISA showed comparable clearance for the two drug conjugates. Furthermore, consistent with relative drug load, the ADC had a greater magnitude of drug deconjugation than the TDC in terms of free plasma MMAE levels. Antibody conjugation had a noticeable, albeit minor, impact on tissue distribution with a general trend toward increased hepatic uptake and reduced levels in other highly vascularized organs. Liver uptakes of ADC and TDC at 5 days postinjection were 2-fold and 1.3-fold higher, respectively, relative to the unmodified antibodies. Taken together, these results indicate that the degree of overall structural modification in anti-STEAP1-MMAE conjugates has a corresponding level of impact on both PK and tissue distribution.
Asunto(s)
Anticuerpos Monoclonales/química , Anticuerpos Monoclonales/farmacocinética , Antígenos de Neoplasias/inmunología , Inmunoconjugados/química , Inmunoconjugados/farmacocinética , Oligopéptidos/química , Oligopéptidos/farmacocinética , Oxidorreductasas/inmunología , Animales , Anticuerpos Monoclonales/sangre , Disulfuros/química , Humanos , Inmunoconjugados/sangre , Masculino , Modelos Moleculares , Oligopéptidos/sangre , Ratas , Ratas Sprague-Dawley , Distribución TisularRESUMEN
Early success with brentuximab vedotin in treating classical Hodgkin lymphoma spurred an influx of at least 20 monomethyl auristatin E (MMAE) antibody-drug conjugates (ADCs) into clinical trials. While three MMAE-ADCs have been approved, most of these conjugates are no longer being investigated in clinical trials. Some auristatin conjugates show limited or no efficacy at tolerated doses, but even for drugs driving initial remissions, tumor regrowth and metastasis often rapidly occur. Here we describe the development of second-generation therapeutic ADCs targeting Lymphocyte antigen 6E (Ly6E) where the tubulin polymerization inhibitor MMAE (Compound 1) is replaced with DNA-damaging agents intended to drive increased durability of response. Comparison of a seco-cyclopropyl benzoindol-4-one (CBI)-dimer (compound 2) to MMAE showed increased potency, activity across more cell lines, and resistance to efflux by P-glycoprotein, a drug transporter commonly upregulated in tumors. Both anti-Ly6E-CBI and -MMAE conjugates drove single-dose efficacy in xenograft and patient-derived xenograft models, but seco-CBI-dimer conjugates showed reduced tumor outgrowth following multiple weeks of treatment, suggesting that they are less susceptible to developing resistance. In parallel, we explored approaches to optimize the targeting antibody. In contrast to immunization with recombinant Ly6E or Ly6E DNA, immunization with virus-like particles generated a high-affinity anti-Ly6E antibody. Conjugates to this antibody improve efficacy versus a previous clinical candidate both in vitro and in vivo with multiple cytotoxics. Conjugation of compound 2 to the second-generation antibody results in a substantially improved ADC with promising preclinical efficacy.
Asunto(s)
Anticuerpos Monoclonales/inmunología , Antígenos de Superficie/inmunología , Antineoplásicos/inmunología , Inmunoconjugados/inmunología , Oligopéptidos/inmunología , Ensayos Antitumor por Modelo de Xenoinjerto/métodos , Animales , Anticuerpos Monoclonales/farmacocinética , Anticuerpos Monoclonales/farmacología , Antineoplásicos/farmacocinética , Antineoplásicos/farmacología , Antineoplásicos Inmunológicos/farmacocinética , Antineoplásicos Inmunológicos/farmacología , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Supervivencia Celular/inmunología , Femenino , Proteínas Ligadas a GPI/inmunología , Células HEK293 , Humanos , Inmunoconjugados/farmacocinética , Inmunoconjugados/farmacología , Ratones SCID , Ratas Sprague-Dawley , Carga Tumoral/efectos de los fármacos , Carga Tumoral/inmunologíaRESUMEN
Calicheamicin antibody-drug conjugates (ADCs) are effective therapeutics for leukemias with two recently approved in the United States: Mylotarg (gemtuzumab ozogamicin) targeting CD33 for acute myeloid leukemia and Besponsa (inotuzumab ozogamicin) targeting CD22 for acute lymphocytic leukemia. Both of these calicheamicin ADCs are heterogeneous, aggregation-prone, and have a shortened half-life due to the instability of the acid-sensitive hydrazone linker in circulation. We hypothesized that we could improve upon the heterogeneity, aggregation, and circulation stability of calicheamicin ADCs by directly attaching the thiol of a reduced calicheamicin to an engineered cysteine on the antibody via a disulfide bond to generate a linkerless and traceless conjugate. We report herein that the resulting homogeneous conjugates possess minimal aggregation and display high in vivo stability with 50% of the drug remaining conjugated to the antibody after 21 days. Furthermore, these calicheamicin ADCs are highly efficacious in mouse models of both solid tumor (HER2+ breast cancer) and hematologic malignancies (CD22+ non-Hodgkin lymphoma). Safety studies in rats with this novel calicheamicin ADC revealed an increased tolerability compared with that reported for Mylotarg. Overall, we demonstrate that applying novel linker chemistry with site-specific conjugation affords an improved, next-generation calicheamicin ADC.
Asunto(s)
Antibióticos Antineoplásicos/uso terapéutico , Calicheamicinas/uso terapéutico , Inmunoconjugados/uso terapéutico , Animales , Antibióticos Antineoplásicos/farmacología , Calicheamicinas/farmacología , Modelos Animales de Enfermedad , Humanos , Inmunoconjugados/farmacología , RatonesRESUMEN
The biological and medicinal impacts of proteolysis-targeting chimeras (PROTACs) and related chimeric molecules that effect intracellular degradation of target proteins via ubiquitin ligase-mediated ubiquitination continue to grow. However, these chimeric entities are relatively large compounds that often possess molecular characteristics, which may compromise oral bioavailability, solubility, and/or in vivo pharmacokinetic properties. We therefore explored the conjugation of such molecules to monoclonal antibodies using technologies originally developed for cytotoxic payloads so as to provide alternate delivery options for these novel agents. In this report, we describe the first phase of our systematic development of antibody-drug conjugates (ADCs) derived from bromodomain-containing protein 4 (BRD4)-targeting chimeric degrader entities. We demonstrate the antigen-dependent delivery of the degrader payloads to PC3-S1 prostate cancer cells along with related impacts on MYC transcription and intracellular BRD4 levels. These experiments culminate with the identification of one degrader conjugate, which exhibits antigen-dependent antiproliferation effects in LNCaP prostate cancer cells.
Asunto(s)
Proteínas de Ciclo Celular/antagonistas & inhibidores , Dipéptidos/farmacología , Compuestos Heterocíclicos con 3 Anillos/farmacología , Inmunoconjugados/farmacología , Proteolisis/efectos de los fármacos , Factores de Transcripción/antagonistas & inhibidores , Anticuerpos Monoclonales/inmunología , Antígenos de Neoplasias/inmunología , Proteínas de Ciclo Celular/metabolismo , Proliferación Celular/efectos de los fármacos , Dipéptidos/síntesis química , Dipéptidos/farmacocinética , Compuestos Heterocíclicos con 3 Anillos/síntesis química , Compuestos Heterocíclicos con 3 Anillos/farmacocinética , Humanos , Inmunoconjugados/química , Inmunoconjugados/inmunología , Oxidorreductasas/inmunología , Células PC-3 , Factores de Transcripción/metabolismo , Proteína Supresora de Tumores del Síndrome de Von Hippel-Lindau/metabolismoRESUMEN
Heterobifunctional compounds that direct the ubiquitination of intracellular proteins in a targeted manner via co-opted ubiquitin ligases have enormous potential to transform the field of medicinal chemistry. These chimeric molecules, often termed proteolysis-targeting chimeras (PROTACs) in the chemical literature, enable the controlled degradation of specific proteins via their direction to the cellular proteasome. In this report, we describe the second phase of our research focused on exploring antibody-drug conjugates (ADCs), which incorporate BRD4-targeting chimeric degrader entities. We employ a new BRD4-binding fragment in the construction of the chimeric ADC payloads that is significantly more potent than the corresponding entity utilized in our initial studies. The resulting BRD4-degrader antibody conjugates exhibit potent and antigen-dependent BRD4 degradation and antiproliferation activities in cell-based experiments. Multiple ADCs bearing chimeric BRD4-degrader payloads also exhibit strong, antigen-dependent antitumor efficacy in mouse xenograft assessments that employ several different tumor models.
Asunto(s)
Antineoplásicos/uso terapéutico , Proteínas de Ciclo Celular/antagonistas & inhibidores , Proliferación Celular/efectos de los fármacos , Inmunoconjugados/uso terapéutico , Neoplasias/tratamiento farmacológico , Proteolisis/efectos de los fármacos , Factores de Transcripción/antagonistas & inhibidores , Animales , Anticuerpos Monoclonales/inmunología , Anticuerpos Monoclonales/farmacocinética , Anticuerpos Monoclonales/uso terapéutico , Antígenos de Neoplasias/inmunología , Antineoplásicos/síntesis química , Antineoplásicos/farmacocinética , Proteínas de Ciclo Celular/metabolismo , Línea Celular Tumoral , Dipéptidos/síntesis química , Dipéptidos/farmacocinética , Dipéptidos/uso terapéutico , Femenino , Compuestos Heterocíclicos con 3 Anillos/síntesis química , Compuestos Heterocíclicos con 3 Anillos/farmacocinética , Compuestos Heterocíclicos con 3 Anillos/uso terapéutico , Humanos , Inmunoconjugados/inmunología , Inmunoconjugados/farmacocinética , Ratones SCID , Oxidorreductasas/inmunología , Factores de Transcripción/metabolismo , Proteína Supresora de Tumores del Síndrome de Von Hippel-Lindau/metabolismo , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
For antibody-drug conjugates to be efficacious and safe, they must be stable in circulation to carry the payload to the site of the targeted cell. Several components of a drug-conjugated antibody are known to influence stability: 1) the site of drug attachment on the antibody, 2) the linker used to attach the payload to the antibody, and 3) the payload itself. In order to support the design and optimization of a high volume of drug conjugates and avoid unstable conjugates prior to testing in animal models, we wanted to proactively identify these potential liabilities. Therefore, we sought to establish an in vitro screening method that best correlated with in vivo stability. While traditionally plasma has been used to assess in vitro stability, our evaluation using a variety of THIOMABTM antibody-drug conjugates revealed several disconnects between the stability assessed in vitro and the in vivo outcomes when using plasma. When drug conjugates were incubated in vitro for 24 h in mouse whole blood rather than plasma and then analyzed by affinity capture LC-MS, we found an improved correlation to in vivo stability with whole blood (R2 = 0.87, coefficient of determination) compared to unfrozen or frozen mouse plasma (R2 = 0.34, 0.01, respectively). We further showed that this whole blood assay was also able to predict in vivo stability of other preclinical species such as rat and cynomolgus monkey, as well as in human. The screening method utilized short (24 h) incubation times, as well as a custom analysis software, allowing increased throughput and in-depth biotransformation characterization. While some instabilities that were more challenging to identify remain, the method greatly enhanced the process of screening, optimizing, and lead candidate selection, resulting in the substantial reduction of animal studies.
Asunto(s)
Cromatografía Liquida/métodos , Inmunoconjugados/química , Espectrometría de Masas/métodos , Animales , Humanos , Técnicas In Vitro , Estabilidad ProteicaRESUMEN
Cytotoxic pyrrolobenzodiazepine (PBD)-dimer molecules are frequently utilized as payloads for antibody-drug conjugates (ADCs), and many examples are currently in clinical development. In order to further explore this ADC payload class, the physicochemical properties of various PBD-dimer molecules were modified by the systematic introduction of acidic and basic moieties into their chemical structures. The impact of these changes on DNA binding, cell membrane permeability, and in vitro antiproliferation potency was, respectively, determined using a DNA alkylation assay, PAMPA assessments, and cell-based cytotoxicity measurements conducted with a variety of cancer lines. The modified PBD-dimer compounds were subsequently incorporated into CD22-targeting ADCs, and these entities were profiled in a variety of in vitro and in vivo experiments. The introduction of a strongly basic moiety into the PBD-dimer scaffold afforded a conjugate with dramatically worsened mouse tolerability properties relative to ADCs derived from related payloads, which lacked the basic group.
Asunto(s)
Benzodiazepinas/química , Dimerización , Inmunoconjugados/efectos adversos , Inmunoconjugados/química , Pirroles/química , Seguridad , Sitios de Unión , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Fenómenos Químicos , ADN/química , ADN/metabolismo , Humanos , Inmunoconjugados/metabolismo , Inmunoconjugados/farmacología , Modelos Moleculares , Conformación de Ácido NucleicoRESUMEN
Antibody-drug conjugates (ADCs) have become an important therapeutic modality for oncology, with three approved by the FDA and over 60 others in clinical trials. Despite the progress, improvements in ADC therapeutic index are desired. Peptide-based ADC linkers that are cleaved by lysosomal proteases have shown sufficient stability in serum and effective payload-release in targeted cells. If the linker can be preferentially hydrolyzed by tumor-specific proteases, safety margin may improve. However, the use of peptide-based linkers limits our ability to modulate protease specificity. Here we report the structure-guided discovery of novel, nonpeptidic ADC linkers. We show that a cyclobutane-1,1-dicarboxamide-containing linker is hydrolyzed predominantly by cathepsin B while the valine-citrulline dipeptide linker is not. ADCs bearing the nonpeptidic linker are as efficacious and stable in vivo as those with the dipeptide linker. Our results strongly support the application of the peptidomimetic linker and present new opportunities for improving the selectivity of ADCs.