RESUMEN
Although inhibiting EGFR-mediated signaling proved to be effective in treating certain types of cancers, a quickly evolved mechanism that either restores the EGFR signaling or activates an alternative pathway for driving the proliferation and survival of malignant cells limits the efficacy and utility of the approach via suppressing the EGFR functionality. Given the fact that overexpression of EGFR is commonly seen in many cancers, an EGFR-targeting antibody-drug conjugate (ADC) can selectively kill cancer cells independently of blocking EGFR-mediated signaling. Herein, we describe SHR-A1307, a novel anti-EGFR ADC, generated from an anti-EGFR antibody with prolonged half-life, and conjugated with a proprietary toxin payload that has increased index of EGFR targeting-dependent versus EGFR targeting-independent cytotoxicity. SHR-A1307 demonstrated strong and sustained antitumor activities in EGFR-positive tumors harboring different oncogenic mutations on EGFR, KRAS, or PIK3CA. Antitumor efficacy of SHR-A1307 correlated with EGFR expression levels in vitro and in vivo, regardless of the mutation status of EGFR signaling mediators and a resultant resistance to EGFR signaling inhibitors. Cynomolgus monkey toxicology study showed that SHR-A1307 is well tolerated with a wide therapeutic index. SHR-A1307 is a promising therapeutic option for EGFR-expressing cancers, including those resistant or refractory to the EGFR pathway inhibitors.
Asunto(s)
Aminobenzoatos/inmunología , Anticuerpos Monoclonales Humanizados/inmunología , Antineoplásicos Inmunológicos/inmunología , Resistencia a Antineoplásicos/efectos de los fármacos , Inmunoconjugados/farmacología , Inmunoconjugados/uso terapéutico , Neoplasias/tratamiento farmacológico , Oligopéptidos/inmunología , Animales , Anticuerpos Monoclonales Humanizados/administración & dosificación , Antineoplásicos Inmunológicos/administración & dosificación , Línea Celular Tumoral , Sistemas de Liberación de Medicamentos/métodos , Receptores ErbB/inmunología , Femenino , Células HEK293 , Humanos , Macaca fascicularis , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Desnudos , Transfección , Carga Tumoral/efectos de los fármacos , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
A convergent and stereoselective total synthesis of the previously assigned structure of azaspiracid-3 has been achieved by a late-stage Nozaki-Hiyama-Kishi coupling to form the C21-C22 bond with the C20 configuration unambiguously established from l-(+)-tartaric acid. Postcoupling steps involved oxidation to an ynone, modified Stryker reduction of the alkyne, global deprotection, and oxidation of the resulting C1 primary alcohol to the carboxylic acid. The synthetic product matched naturally occurring azaspiracid-3 by mass spectrometry, but differed both chromatographically and spectroscopically.
Asunto(s)
Productos Biológicos/química , Furanos/síntesis química , Piranos/síntesis química , Espectroscopía de Resonancia Magnética con Carbono-13 , Cromatografía Liquida , Furanos/química , Estructura Molecular , Oxidación-Reducción , Espectroscopía de Protones por Resonancia Magnética , Piranos/química , Estereoisomerismo , Espectrometría de Masas en TándemRESUMEN
Azaspiracids (AZAs) are a group of biotoxins that cause food poisoning in humans. These toxins are produced by small marine dinoflagellates such as Azadinium spinosum and accumulate in shellfish. Ovine polyclonal antibodies were produced and used to develop an ELISA for quantitating AZAs in shellfish, algal cells, and culture supernatants. Immunizing antigens were prepared from synthetic fragments of the constant region of AZAs, while plate coating antigen was prepared from AZA-1. The ELISA provides a sensitive and rapid analytical method for screening large numbers of samples. It has a working range of 0.45-8.6 ng/mL and a limit of quantitation for total AZAs in whole shellfish at 57 µg/kg, well below the maximum permitted level set by the European Commission. The ELISA has good cross-reactivity to AZA-1-10, -33, and -34 and 37-epi-AZA-1. Naturally contaminated Irish mussels gave similar results whether they were cooked or uncooked, indicating that the ELISA also detects 22-carboxy-AZA metabolites (e.g., AZA-17 and AZA-19). ELISA results showed excellent correlation with LC-MS/MS analysis, both for mussel extract spiked with AZA-1 and for naturally contaminated Irish mussels. The assay is therefore well suited to screening for AZAs in shellfish samples intended for human consumption, as well as for studies on AZA metabolism.
Asunto(s)
Bivalvos/química , Dinoflagelados/metabolismo , Ensayo de Inmunoadsorción Enzimática/métodos , Contaminación de Alimentos/análisis , Toxinas Marinas/análisis , Mariscos/análisis , Compuestos de Espiro/análisis , Animales , Bivalvos/parasitología , Toxinas Marinas/metabolismo , Mariscos/parasitología , Compuestos de Espiro/metabolismoRESUMEN
An efficient synthesis of the C1-C21 fragment of azaspiracids-1 and -3 is described. This features a Nozaki-Hiyama-Kishi reaction to couple the AB and CD ring precursors and formation of the THF-fused ABCD trioxadispiroketal system under thermodynamic conditions.
Asunto(s)
Furanos/síntesis química , Toxinas Marinas/síntesis química , Piranos/síntesis química , Compuestos de Espiro/síntesis química , Furanos/química , Toxinas Marinas/química , Estructura Molecular , Piranos/química , Compuestos de Espiro/química , Estereoisomerismo , TermodinámicaRESUMEN
The development of general, sensitive, portable, and quantitative assays for the azaspiracid (AZA) class of marine toxins is urgently needed. Use of a synthetic hapten containing rings F-I of AZA to generate antibodies that cross-react with the AZAs via their common C28-C40 domain and use of these antibodies in ELISA and immunoaffinity columns are reported. This approach has many advantages over using intact azaspiracids (AZAs) derived from environmental samples or total synthesis as haptens for antibody development. A derivative of the levorotatory C28-C40 azaspiracid domain (1) was synthesized efficiently using a one-pot Staudinger reduction/intramolecular aza-Wittig reaction-imine capture sequence to form the H-I ring spiroaminal and a double intramolecluar hetero-Michael addition to assemble the F-G ring ketal. Conjugation of the hapten 1 to cBSA and immunization in sheep generated antibodies that recognized and bound to ovalbumin-conjugated 1 in the absence of AZA1. This binding was inhibited by 1 in a concentration-dependent manner. A mixture of AZA1, AZA2, AZA3, and AZA6 caused a degree of inhibition of antibody binding consistent with its total AZA content, rather than just its content of AZA1. This result suggests that the antibodies also have a similar affinity for AZA2, AZA3, and AZA6 as they do for AZA1 and that such antibodies are suitable for analysis of AZAs in shellfish samples.