Pyrrolobenzodiazepine Dimer Antibody–Drug Conjugates: Synthesis and Evaluation of Noncleavable Drug-Linkers

Gregson, Stephen J.; Masterson, Luke A.; Wei, BinQing; Pillow, Thomas H.; Spencer, Susan D.; Kang, Gyoung‐Dong; Yu, Shang‐Fan; Raab, Helga; Lau, Jeffrey; Li, Guangmin; Phillips, Gail D. Lewis; Gunzner-Toste, Janet; Safina, Brian S.; Ohri, Rachana; Darwish, Martine; Kozak, Katherine R.; Cruz-Chuh, Josefa dela; Polson, Andrew G.; Flygare, John A.; Howard, Philip W.

doi:10.1021/acs.jmedchem.7b00736

Cited by 31 publications

(23 citation statements)

References 48 publications

(106 reference statements)

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“…Attenuation of ADC potency arises because non-cleavable linkers lack a defined cleavage mechanism; after intracellular protein degradation, final active metabolites retain the linker component. It has been demonstrated that this drawback can be circumvented in some cases by fine-tuning the chemical structures of the linker and payload 42 , 43 . However, the success of such efforts depends on the choice of the linker installation sites, conjugation modality, and payload.…”

Section: Discussionmentioning

confidence: 99%

Glutamic acid–valine–citrulline linkers ensure stability and efficacy of antibody–drug conjugates in mice

et al. 2018

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Valine–citrulline linkers are commonly used as enzymatically cleavable linkers for antibody–drug conjugates. While stable in human plasma, these linkers are unstable in mouse plasma due to susceptibility to an extracellular carboxylesterase. This instability often triggers premature release of drugs in mouse circulation, presenting a molecular design challenge. Here, we report that an antibody–drug conjugate with glutamic acid–valine–citrulline linkers is responsive to enzymatic drug release but undergoes almost no premature cleavage in mice. We demonstrate that this construct exhibits greater treatment efficacy in mouse tumor models than does a valine–citrulline-based variant. Notably, our antibody–drug conjugate contains long spacers facilitating the protease access to the linker moiety, indicating that our linker assures high in vivo stability despite a high degree of exposure. This technology could add flexibility to antibody–drug conjugate design and help minimize failure rates in pre-clinical studies caused by linker instability.

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Section: Discussionmentioning

confidence: 99%

Glutamic acid–valine–citrulline linkers ensure stability and efficacy of antibody–drug conjugates in mice

et al. 2018

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“…PBD dimers are a class of compounds that form sequence-selective DNA crosslinks in the minor groove of DNA, leading to cell death (28,29) and thereby offering an alternative mechanism of action for tumor targeting. New classes of PBD payloads with noncleavable linkers (30), including the benzyl tether-linked PBD SG3376 (31), are also being synthesized.…”

Section: Introductionmentioning

confidence: 99%

SLC46A3 as a Potential Predictive Biomarker for Antibody–Drug Conjugates Bearing Noncleavable Linked Maytansinoid and Pyrrolobenzodiazepine Warheads

Kinneer¹,

Meekin²,

Tiberghien

et al. 2018

Clinical Cancer Research

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Antibody-drug conjugates (ADC) utilizing noncleavable linker drugs have been approved for clinical use, and several are in development targeting solid and hematologic malignancies including multiple myeloma. Currently, there are no reliable biomarkers of activity for these ADCs other than presence of the targeted antigen. We observed that certain cell lines are innately resistant to such ADCs, and sought to uncover the underlying mechanism of resistance. The expression of 43 lysosomal membrane target genes was evaluated in cell lines resistant to ADCs bearing the noncleavable linker, pyrrolobenzodiazepine payload SG3376, The functional relevance of SLC46A3, a lysosomal transporter of noncleavable ADC catabolites whose expression uniquely correlated with SG3376 resistance, was assessed using EPHA2-, HER2-, and BCMA-targeted ADCs and isogenic cells overexpressing or genetically inactivated for expression was also examined in patient-derived xenograft and models of acquired T-DM1 resistance and multiple myeloma bone marrow samples by RT-PCR. Loss of expression was found to be a mechanism of innate and acquired resistance to ADCs bearing DM1 and SG3376. Sensitivity was restored in refractory lines upon introduction of, suggesting that expression of may be more predictive of activity than target antigen levels alone. Interrogation of primary multiple myeloma samples indicated a range of expression, including samples with undetectable levels like multiple myeloma cell lines resistant to BCMA-targeting DM1 and SG3376 ADCs. Our findings support as a potential patient selection biomarker with immediate relevance to clinical trials involving these ADCs.

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“…The next set of experiments used PBD SG3552 and its linker-derivative SG3376 (45, 46) (Figure 1B). This toxin-linker combination was chosen as it was designed to have fewer off-target effects (45, 47) and was shown to be more potent against trypanosomes in preliminary experiments.…”

Section: Resultsmentioning

confidence: 99%

A single dose of antibody-drug conjugate cures a stage 1 model of African trypanosomiasis

MacGregor¹,

González-Muñoz²,

Jobe³

et al. 2019

Preprint

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22Infections of humans and livestock with African trypanosomes are treated with drugs 23 introduced decades ago that are not always fully effective and often have severe 24 side effects. Here, the trypanosome haptoglobin-haemoglobin receptor (HpHbR) has 25 been exploited as a route of uptake for an antibody-drug conjugate (ADC) that is 26 completely effective against Trypanosoma brucei in the standard mouse model of 27 infection. Recombinant human anti-HpHbR monoclonal antibodies were isolated and 28 shown to be internalised in a receptor-dependent manner. Antibodies were 29 conjugated to a pyrrolobenzodiazepine (PBD) toxin and killed T. brucei in vitro at 30 picomolar concentrations. A single therapeutic dose (0.25 mg/kg) of a HpHbR 31 antibody-PBD conjugate completely cured a T. brucei mouse infection within 2 days 32 with no re-emergence of infection over a subsequent time course of 77 days. These 33 experiments provide a demonstration of how ADCs can be exploited to treat 34 protozoal diseases that desperately require new therapeutics. 35 36 Author Summary 37Here we show that antibody-drug conjugates (ADCs) can be re-purposed from 38 cancer immunotherapeutics to anti-protozoals by changing the specificity of the 39 immunoglobulin to target a trypanosome cell surface receptor. Trypanosomes were 40 used as a model system due to the availability of receptor null cell lines that allowed 41 the unambiguous demonstration that ADCs targeted to a parasite surface receptor 42 could be specifically internalised via receptor-mediated endocytosis. A single low 43 dose of the resulting ADC was able to cure a stage 1 mouse model of trypanosome 44 infection. We have used toxins and conjugation chemistry that are identical to anti-45 3 cancer ADCs demonstrating the ability to piggy-back onto the huge research efforts 46 and resources that are being invested in the development of such ADCs. 47The potential for development of ADCs against a wide range of human pathogens is 48 vast, where only epitope binding sites need vary in order to provide selectivity. This 49 provides a far-reaching opportunity for the rapid development of novel anti-50 protozoals for the targeted killing of a wide range of pathogens that cause disease 51 worldwide, especially in developing countries.

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Pyrrolobenzodiazepine Dimer Antibody–Drug Conjugates: Synthesis and Evaluation of Noncleavable Drug-Linkers

Cited by 31 publications

References 48 publications

Glutamic acid–valine–citrulline linkers ensure stability and efficacy of antibody–drug conjugates in mice

Glutamic acid–valine–citrulline linkers ensure stability and efficacy of antibody–drug conjugates in mice

SLC46A3 as a Potential Predictive Biomarker for Antibody–Drug Conjugates Bearing Noncleavable Linked Maytansinoid and Pyrrolobenzodiazepine Warheads

A single dose of antibody-drug conjugate cures a stage 1 model of African trypanosomiasis

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