A Potent Anti-CD70 Antibody–Drug Conjugate Combining a Dimeric Pyrrolobenzodiazepine Drug with Site-Specific Conjugation Technology

Jeffrey, Scott C.; Burke, Patrick; Lyon, Robert P.; Meyer, David W.; Sussman, Django; Anderson, Martha E.; Hunter, Joshua H.; Leiske, Chris; Miyamoto, Jamie B.; Nicholas, Nicole D.; Okeley, Nicole M.; Sanderson, Russell J.; Stone, Ivan J.; Zeng, Weiping; Gregson, Stephen J.; Masterson, Luke A.; Tiberghien, Arnaud; Howard, Philip W.; Thurston, David E.; Law, Che‐Leung; Senter, Peter D.

doi:10.1021/bc400217g

Cited by 225 publications

(243 citation statements)

References 38 publications

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“…For example, ADCs carrying the potent DNA interacting agent calicheamicin are tolerated by humans only at very low doses and one such ADC, gemtuzumab ozogamicin, was withdrawn from the market due to a narrow therapeutic index and related safety concerns (15). ADCs of pyrrolobenzodiazepine (PBD) dimers, potent DNA cross-linkers, have recently been advanced into clinical evaluation (16)(17)(18). These ADCs incorporate derivatives of the PBD dimer SJG-136, a highly toxic small molecule with a maximally tolerated dose (MTD) of $1.2 mg/kg in humans (19).…”

Section: Introductionmentioning

confidence: 99%

A New Class of Antibody–Drug Conjugates with Potent DNA Alkylating Activity

Miller

Fishkin

et al. 2016

Molecular Cancer Therapeutics

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The promise of tumor-selective delivery of cytotoxic agents in the form of antibody-drug conjugates (ADC) has now been realized, evidenced by the approval of two ADCs, both of which incorporate highly cytotoxic tubulin-interacting agents, for cancer therapy. An ongoing challenge remains in identifying potent agents with alternative mechanisms of cell killing that can provide ADCs with high therapeutic indices and favorable tolerability. Here, we describe the development of a new class of potent DNA alkylating agents that meets these objectives. Through chemical design, we changed the mechanism of action of our novel DNA cross-linking agent to a monofunctional DNA alkylator. This modification, coupled with linker optimization, generated ADCs that were well tolerated in mice and demonstrated robust antitumor activity in multiple tumor models at doses 1.5% to 3.5% of maximally tolerated levels. These properties underscore the considerable potential of these purpose-created, unique DNAinteracting conjugates for broadening the clinical application of ADC technology. Mol Cancer Ther; 15(8); 1870-8. Ó2016 AACR.

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Section: Introductionmentioning

confidence: 99%

A New Class of Antibody–Drug Conjugates with Potent DNA Alkylating Activity

Miller

Fishkin

et al. 2016

Molecular Cancer Therapeutics

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“…Relative to the heterogeneous mixtures created using conventional conjugation methodologies, site-specifically conjugated TDCs demonstrated equivalent in vivo potency, improved PK, and an expanded therapeutic window (6,7). Although this approach may be useful for generating site-specifically conjugated ADCs, THIOMABS produced using this process are not directly amenable to conjugation, but instead, require a multistep process that includes decapping of the engineered cysteine residues, which inevitably results in the partial breaking and reformation of structurally important internal disulfide bonds.…”

mentioning

confidence: 99%

A general approach to site-specific antibody drug conjugates

Tian

Manibusan

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Using an expanded genetic code, antibodies with site-specifically incorporated nonnative amino acids were produced in stable cell lines derived from a CHO cell line with titers over 1 g/L. Using anti-5T4 and anti-Her2 antibodies as model systems, site-specific antibody drug conjugates (NDCs) were produced, via oxime bond formation between ketones on the side chain of the incorporated nonnative amino acid and hydroxylamine functionalized monomethyl auristatin D with either protease-cleavable or noncleavable linkers. When noncleavable linkers were used, these conjugates were highly stable and displayed improved in vitro efficacy as well as in vivo efficacy and pharmacokinetic stability in rodent models relative to conventional antibody drug conjugates conjugated through either engineered surface-exposed or reduced interchain disulfide bond cysteine residues. The advantages of the oximebonded, site-specific NDCs were even more apparent when lowantigen-expressing (2+) target cell lines were used in the comparative studies. NDCs generated with protease-cleavable linkers demonstrated that the site of conjugation had a significant impact on the stability of these rationally designed prodrug linkers. In a single-dose rat toxicology study, a site-specific anti-Her2 NDC was well tolerated at dose levels up to 90 mg/kg. These experiments support the notion that chemically defined antibody conjugates can be synthesized in commercially relevant yields and can lead to antibody drug conjugates with improved properties relative to the heterogeneous conjugates formed by nonspecific chemical modification.A ntibody drug conjugates (ADCs) are emerging as a new class of anticancer therapeutics that combine the efficacy of small-molecule therapeutics with the targeting ability of an antibody (Ab) (1, 2). By combining these two components into a single molecular entity, highly cytotoxic small-molecule drugs (SMDs) can be delivered to cancerous target tissues, thereby enhancing efficacy while reducing the potential systemic toxic side effects of the SMD. Conventional ADCs are typically produced by conjugating the SMD to the Ab through the side chains of either surface-exposed lysines or free cysteines generated through reduction of interchain disulfide bonds (3, 4). Because antibodies contain many lysine and cysteine residues, conventional conjugation typically produces heterogeneous mixtures that present challenges with respect to analytical characterization and manufacturing. Furthermore, the individual constituents of these mixtures exhibit different pharmacology with respect to their pharmacokinetic, efficacy, and safety profiles, hindering a rational approach to optimizing this modality (5).Recently, it was reported that the pharmacological profile of ADCs may be improved by applying site-specific conjugation technologies that make use of surface-exposed cysteine residues engineered into antibodies (THIOMABS) that are then conjugated to the SMD, resulting in site-specifically conjugated ADCs (TDCs) with defined Ab-drug ratios. Rel...

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“…SGN-CD123A is generated by conjugation of SGD-1910, a chemical intermediate that contains both the pyrrolobenzodiazepine dimer (PBD) payload and the valine-alanine dipeptide linker, to the two engineered cysteine residues of h7G3ec (ref. 16; Fig. 2A).…”

Section: Conjugation and Characterization Of Sgn-cd123amentioning

confidence: 93%

“…S4. The conjugation of PBD dimers to antibodies with engineered cysteines (S239C) has been described previously (16). The nonbinding control ADC is composed of a recombinant humanized IgG1 with S239C-engineered cysteine mutations and PBD dimer drug linker.…”

Section: Methodsmentioning

confidence: 99%

Characterization of SGN-CD123A, A Potent CD123-Directed Antibody–Drug Conjugate for Acute Myeloid Leukemia

Sutherland

et al. 2018

Molecular Cancer Therapeutics

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Treatment choices for acute myelogenous leukemia (AML) patients resistant to conventional chemotherapies are limited and novel therapeutic agents are needed. IL3 receptor alpha (IL3Ra, or CD123) is expressed on the majority of AML blasts, and there is evidence that its expression is increased on leukemic relative to normal hematopoietic stem cells, which makes it an attractive target for antibody-based therapy. Here, we report the generation and preclinical characterization of SGN-CD123A, an antibody-drug conjugate using the pyrrolobenzodiazepine dimer (PBD) linker and a humanized CD123 antibody with engineered cysteines for site-specific conjugation. Mechanistically, SGN-CD123A induces activation of DNA damage response pathways, cell-cycle changes, and apoptosis in AML cells. In vitro, SGN-CD123A-mediated potent cytotoxicity of 11/12 CD123 þ AML cell lines and 20/23 primary samples from AML patients, including those with unfavorable cytogenetic profiles or FLT3 mutations. In vivo, SGN-CD123A treatment led to AML eradication in a disseminated disease model, remission in a subcutaneous xenograft model, and significant growth delay in a multidrug resistance xenograft model. Moreover, SGN-CD123A also resulted in durable complete remission of a patient-derived xenograft AML model. When combined with a FLT3 inhibitor quizartinib, SGN-CD123A enhanced the activity of quizartinib against two FLT3-mutated xenograft models. Overall, these data demonstrate that SGN-CD123A is a potent antileukemic agent, supporting an ongoing trial to evaluate its safety and efficacy in AML patients (NCT02848248). Mol Cancer Ther; 17(2); 554-64. Ó2017 AACR.

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A Potent Anti-CD70 Antibody–Drug Conjugate Combining a Dimeric Pyrrolobenzodiazepine Drug with Site-Specific Conjugation Technology

Cited by 225 publications

References 38 publications

A New Class of Antibody–Drug Conjugates with Potent DNA Alkylating Activity

A New Class of Antibody–Drug Conjugates with Potent DNA Alkylating Activity

A general approach to site-specific antibody drug conjugates

Characterization of SGN-CD123A, A Potent CD123-Directed Antibody–Drug Conjugate for Acute Myeloid Leukemia

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