Publications by authors named "Andrew G Polson"

31 Publications

A Novel Calicheamicin Antibody-Drug Conjugate with Improved Properties.

Mol Cancer Ther 2021 Mar 15. Epub 2021 Mar 15.

Research and Early Development, Genentech, Inc.

Calicheamicin antibody-drug conjugates (ADCs) are effective therapeutics for leukemias with two recently approved in the United States, Mylotarg (gemtuzumab ozogamicin) targeting CD33 for AML and Besponsa (inotuzumab ozogamicin) targeting CD22 for ALL. 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 to that reported for Mylotarg. Overall, we demonstrate that applying novel linker chemistry with site-specific conjugation affords an improved, next generation calicheamicin ADC.
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http://dx.doi.org/10.1158/1535-7163.MCT-20-0035DOI Listing
March 2021

Preclinical optimization of Ly6E-targeted ADCs for increased durability and efficacy of anti-tumor response.

MAbs 2021 Jan-Dec;13(1):1862452

Antibody Engineering, Genentech Inc , South San Francisco, CA, USA.

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 ) is replaced with DNA-damaging agents intended to drive increased durability of response. Comparison of a -cyclopropyl benzoindol-4-one (CBI)-dimer (compound ) to MMAE showed increased potency, activity across more cell lines, and resistance to efflux by -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 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 and with multiple cytotoxics. Conjugation of compound to the second-generation antibody results in a substantially improved ADC with promising preclinical efficacy.
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http://dx.doi.org/10.1080/19420862.2020.1862452DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7784788PMC
December 2020

An Anti-CD22--CBI-Dimer Antibody-Drug Conjugate (ADC) for the Treatment of Non-Hodgkin Lymphoma That Provides a Longer Duration of Response than Auristatin-Based ADCs in Preclinical Models.

Mol Cancer Ther 2021 02 3;20(2):340-346. Epub 2020 Dec 3.

Research and Early Development, Genentech Inc., South San Francisco, California.

We are interested in developing a second generation of antibody-drug conjugates (ADCs) for the treatment of non-Hodgkin lymphoma (NHL) that could provide a longer duration of response and be more effective in indolent NHL than the microtubule-inhibiting ADCs pinatuzumab vedotin [anti-CD22-vc-monomethyl auristatin E (MMAE)] and polatuzumab vedotin (anti-CD79b-vc-MMAE). Pinatuzumab vedotin (anti-CD22-vc-MMAE) and polatuzumab vedotin (anti-CD79b-vc-MMAE) are ADCs that contain the microtubule inhibitor MMAE. Clinical trial data suggest that these ADCs have promising efficacy for the treatment of NHL; however, some patients do not respond or become resistant to the ADCs. We tested an anti-CD22 ADC with a -CBI-dimer payload, thio-Hu anti-CD22-(LC:K149C)-SN36248, and compared it with pinatuzumab vedotin for its efficacy and duration of response in xenograft models and its ability to deplete normal B cells in cynomolgus monkeys. We found that anti-CD22-(LC:K149C)-SN36248 was effective in xenograft models resistant to pinatuzumab vedotin, gave a longer duration of response, had a different mechanism of resistance, and was able to deplete normal B cells better than pinatuzumab vedotin. These studies provide evidence that anti-CD22-(LC:K149C)-SN36248 has the potential for longer duration of response and more efficacy in indolent NHL than MMAE ADCs and may provide the opportunity to improve outcomes for patients with NHL.
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http://dx.doi.org/10.1158/1535-7163.MCT-20-0046DOI Listing
February 2021

Evaluation and use of an anti-cynomolgus monkey CD79b surrogate antibody-drug conjugate to enable clinical development of polatuzumab vedotin.

Br J Pharmacol 2019 10 24;176(19):3805-3818. Epub 2019 Aug 24.

Department of Pharmacokinetic and Pharmacodynamic Sciences, Genentech, Inc., South San Francisco, CA, USA.

Background And Purpose: Polatuzumab vedotin is an antibody-drug conjugate (ADC) being developed for non-Hodgkin's lymphoma. It contains a humanized anti-CD79b IgG1 monoclonal antibody linked to monomethyl auristatin E (MMAE), an anti-mitotic agent. Polatuzumab vedotin binds to human CD79b only. Therefore, a surrogate ADC that binds to cynomolgus monkey CD79b was used to determine CD79b-mediated pharmacological effects in the monkey and to enable first-in-human clinical trials.

Experimental Approach: Polatuzumab vedotin, the surrogate ADC, and the corresponding antibodies were evaluated in different assays in vitro and in animals. In vitro assessments included binding to peripheral blood mononuclear cells from different species, binding to a human and monkey CD79b-expressing cell line, binding to human Fcγ receptors, and stability in plasma across species. In vivo, ADCs were assessed for anti-tumour activity in mice, pharmacokinetics/pharmacodynamics in monkeys, and toxicity in rats and monkeys.

Key Results: Polatuzumab vedotin and surrogate ADC bind with similar affinity to human and cynomolgus monkey B cells, respectively. Comparable in vitro plasma stability, in vivo anti-tumour activity, and mouse pharmacokinetics were also observed between the surrogate ADC and polatuzumab vedotin. In monkeys, only the surrogate ADC showed B-cell depletion and B-cell-mediated drug disposition, but both ADCs showed similar MMAE-driven myelotoxicity, as expected.

Conclusions And Implications: The suitability of the surrogate ADC for evaluation of CD79b-dependent pharmacology was demonstrated, and anti-tumour activity, pharmacokinetics/pharmacodynamics, and toxicity data with both ADCs supported the entry of polatuzumab vedotin into clinical trials.
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http://dx.doi.org/10.1111/bph.14784DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6780994PMC
October 2019

Antibody-Drug Conjugates Derived from Cytotoxic seco-CBI-Dimer Payloads Are Highly Efficacious in Xenograft Models and Form Protein Adducts In Vivo.

Bioconjug Chem 2019 05 22;30(5):1356-1370. Epub 2019 Apr 22.

Genentech Inc. , 1 DNA Way , South San Francisco , California 94080 , United States.

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.
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http://dx.doi.org/10.1021/acs.bioconjchem.9b00133DOI Listing
May 2019

Phase I study of the anti-FcRH5 antibody-drug conjugate DFRF4539A in relapsed or refractory multiple myeloma.

Blood Cancer J 2019 02 4;9(2):17. Epub 2019 Feb 4.

Sarah Cannon Research Institute, Nashville, TN, USA.

FcRH5 is a cell surface marker enriched on malignant plasma cells when compared to other hematologic malignancies and normal tissues. DFRF4539A is an anti-FcRH5 antibody-drug conjugated to monomethyl auristatin E (MMAE), a potent anti-mitotic agent. This phase I study assessed safety, tolerability, maximum tolerated dose (MTD), anti-tumor activity, and pharmacokinetics of DFRF4539A in patients with relapsed/refractory multiple myeloma. DFRF4539A was administered at 0.3-2.4 mg/kg every 3 weeks or 0.8-1.1 mg/kg weekly as a single-agent by intravenous infusion to 39 patients. Exposure of total antibody and antibody-conjugate-MMAE analytes was linear across the doses tested. There were 37 (95%) adverse events (AEs), 8 (21%) serious AEs, and 15 (39%) AEs ≥ grade 3. Anemia (n = 10, 26%) was the most common AE considered related to DFRF4539A. Two cases of grade 3 acute renal failure were attributed to DFRF4539A. There were no deaths; the MTD was not reached. DFRF4539A demonstrated limited activity in patients at the doses tested with 2 (5%) partial response, 1 (3%) minimal response, 18 (46%) stable disease, and 16 (41%) progressive disease. FcRH5 was confirmed to be expressed and occupied by antibody post-treatment and thus remains a valid myeloma target. Nevertheless, this MMAE-based antibody-drug-conjugate targeting FcRH5 was unsuccessful for myeloma.
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http://dx.doi.org/10.1038/s41408-019-0178-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6362066PMC
February 2019

Preclinical pharmacokinetics and pharmacodynamics of DCLL9718A: An antibody-drug conjugate for the treatment of acute myeloid leukemia.

MAbs 2018 Nov-Dec;10(8):1312-1321. Epub 2018 Oct 2.

a Preclinical Translational Pharmacokinetics Department , Genentech Inc. , South San Francisco , CA , USA.

Few treatment options are available for acute myeloid leukemia (AML) patients. DCLL9718A is an antibody-drug conjugate that targets C-type lectin-like molecule-1 (CLL-1). This receptor is prevalent on monocytes, neutrophils, and AML blast cells, and unlike CD33, is not expressed on hematopoietic stem cells, thus providing possible hematopoietic recovery. DCLL9718A comprises an anti-CLL-1 IgG1 antibody (MCLL0517A) linked to a pyrrolobenzodiazepine (PBD) dimer payload, via a cleavable disulfide-labile linker. Here, we characterize the in vitro and in vivo stability, the pharmacokinetics (PK) and pharmacodynamics (PD) of DCLL9718A and MCLL0517A in rodents and cynomolgus monkeys. Three key PK analytes were measured in these studies: total antibody, antibody-conjugated PBD dimer and unconjugated PBD dimer. In vitro, DCLL9718A, was stable with most (> 80%) of the PBD dimer payload remaining conjugated to the antibody over 96 hours. This was recapitulated in vivo with antibody-conjugated PBD dimer clearance estimates similar to DCLL9718A total antibody clearance. Both DCLL9718A and MCLL0517A showed linear PK in the non-binding rodent species, and non-linear PK in cynomolgus monkeys, a binding species. The PK data indicated minimal impact of conjugation on the disposition of DCLL9718A total antibody. Finally, in cynomolgus monkey, MCLL0517A showed target engagement at all doses tested (0.5 and 20 mg/kg) as measured by receptor occupancy, and DCLL9718A (at doses of 0.05, 0.1 and 0.2 mg/kg) showed strong PD activity as evidenced by notable reduction in monocytes and neutrophils.
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http://dx.doi.org/10.1080/19420862.2018.1517565DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6284592PMC
June 2019

An Anti-CLL-1 Antibody-Drug Conjugate for the Treatment of Acute Myeloid Leukemia.

Clin Cancer Res 2019 02 29;25(4):1358-1368. Epub 2018 Jun 29.

Research and Early Development, Genentech Inc., South San Francisco, California.

Purpose: The treatment of acute myeloid leukemia (AML) has not significantly changed in 40 years. Cytarabine- and anthracycline-based chemotherapy induction regimens (7 + 3) remain the standard of care, and most patients have poor long-term survival. The reapproval of Mylotarg, an anti-CD33-calicheamicin antibody-drug conjugate (ADC), has demonstrated ADCs as a clinically validated option to enhance the effectiveness of induction therapy. We are interested in developing a next-generation ADC for AML to improve upon the initial success of Mylotarg.

Experimental Design: The expression pattern of CLL-1 and its hematopoietic potential were investigated. A novel anti-CLL-1-ADC, with a highly potent pyrrolobenzodiazepine (PBD) dimer conjugated through a self-immolative disulfide linker, was developed. The efficacy and safety profiles of this ADC were evaluated in mouse xenograft models and in cynomolgus monkeys.

Results: We demonstrate that CLL-1 shares similar prevalence and trafficking properties that make CD33 an excellent ADC target for AML, but lacks expression on hematopoietic stem cells that hampers current CD33-targeted ADCs. Our anti-CLL-1-ADC is highly effective at depleting tumor cells in AML xenograft models and lacks target independent toxicities at doses that depleted target monocytes and neutrophils in cynomolgus monkeys.

Conclusions: Collectively, our data suggest that an anti-CLL-1-ADC has the potential to become an effective and safer treatment for AML in humans, by reducing and allowing for faster recovery from initial cytopenias than the current generation of ADCs for AML.
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http://dx.doi.org/10.1158/1078-0432.CCR-18-0333DOI Listing
February 2019

Prediction of non-linear pharmacokinetics in humans of an antibody-drug conjugate (ADC) when evaluation of higher doses in animals is limited by tolerability: Case study with an anti-CD33 ADC.

MAbs 2018 07 18;10(5):738-750. Epub 2018 May 18.

a Preclinical Translational Pharmacokinetics Department.

For antibody-drug conjugates (ADCs) that carry a cytotoxic drug, doses that can be administered in preclinical studies are typically limited by tolerability, leading to a narrow dose range that can be tested. For molecules with non-linear pharmacokinetics (PK), this limited dose range may be insufficient to fully characterize the PK of the ADC and limits translation to humans. Mathematical PK models are frequently used for molecule selection during preclinical drug development and for translational predictions to guide clinical study design. Here, we present a practical approach that uses limited PK and receptor occupancy (RO) data of the corresponding unconjugated antibody to predict ADC PK when conjugation does not alter the non-specific clearance or the antibody-target interaction. We used a 2-compartment model incorporating non-specific and specific (target mediated) clearances, where the latter is a function of RO, to describe the PK of anti-CD33 ADC with dose-limiting neutropenia in cynomolgus monkeys. We tested our model by comparing PK predictions based on the unconjugated antibody to observed ADC PK data that was not utilized for model development. Prospective prediction of human PK was performed by incorporating in vitro binding affinity differences between species for varying levels of CD33 target expression. Additionally, this approach was used to predict human PK of other previously tested anti-CD33 molecules with published clinical data. The findings showed that, for a cytotoxic ADC with non-linear PK and limited preclinical PK data, incorporating RO in the PK model and using data from the corresponding unconjugated antibody at higher doses allowed the identification of parameters to characterize monkey PK and enabled human PK predictions.
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http://dx.doi.org/10.1080/19420862.2018.1465160DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6150628PMC
July 2018

Intratumoral Payload Concentration Correlates with the Activity of Antibody-Drug Conjugates.

Mol Cancer Ther 2018 03 18;17(3):677-685. Epub 2018 Jan 18.

Drug Metabolism & Pharmacokinetics, Genentech Inc., South San Francisco, California.

Antibody-drug conjugates (ADC) have become important scaffolds for targeted cancer therapies. However, ADC exposure-response correlation is not well characterized. We demonstrated that intratumor payload exposures correlated well with the corresponding efficacies of several disulfide-linked ADCs, bearing an DNA alkylating agent, pyrrolo[2,1-c][1,4]benzodiazepine-dimer (PBD), in HER2-expressing xenograft models. The correlation suggests that a threshold concentration of intratumor payload is required to support sustained efficacy and an ADC can deliver an excessive level of payload to tumors that does not enhance efficacy ("Plateau" effect). In contrast to tumor PBD concentrations, related assessments of systemic exposures, plasma stability, and drug-to-antibody ratio changes of related ADCs did not consistently rationalize the observed ADC efficacies. A minimal efficacious dose could be determined by ADC dose-fractionation studies in the xenograft models. Mechanistic investigations revealed that both linker immolation and linker disulfide stability are the key factors that determine intratumor PBD concentrations. Overall, this study demonstrates how a linker design can impact ADC efficacy and that the intratumor exposure of a payload drug as the molecular mechanism quantitatively correlate with and predict the antitumor efficacy of ADCs. .
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http://dx.doi.org/10.1158/1535-7163.MCT-17-0697DOI Listing
March 2018

Design, synthesis, and biological evaluation of pyrrolobenzodiazepine-containing hypoxia-activated prodrugs.

Bioorg Med Chem Lett 2017 12 13;27(23):5300-5304. Epub 2017 Oct 13.

Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA.

The ability of various pyrrolobenzodiazepine(PBD)-containing cytotoxic compounds to function as hypoxia-activated prodrugs was assessed. These molecules incorporated a 1-methyl-2-nitro-1H-imidazole hypoxia-activated trigger (present in the clinically evaluated compound TH-302) in a manner that masked a reactive imine moiety required for cytotoxic activity. Incubation of the prodrugs with cytochrome P450-reductase under normoxic and hypoxic conditions revealed that some, but not all, were efficient substrates for the enzyme. In these experiments, prodrugs derived from PBD-monomers underwent rapid conversion to the parent cytotoxic compounds under low-oxygen conditions while related PBD-dimers did not. The ability of a given prodrug to function as an efficient cytochrome P450-reductase substrate correlated with the ratio of cytotoxic potencies measured for the compound against NCI460 cells under normoxic and hypoxic conditions.
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http://dx.doi.org/10.1016/j.bmcl.2017.10.023DOI Listing
December 2017

Stabilizing a Tubulysin Antibody-Drug Conjugate To Enable Activity Against Multidrug-Resistant Tumors.

ACS Med Chem Lett 2017 Oct 5;8(10):1037-1041. Epub 2017 Sep 5.

Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, United States.

The tubulysins are promising anticancer cytotoxic agents due to the clinical validation of their mechanism of action (microtubule inhibition) and their particular activity against multidrug-resistant tumor cells. Yet their high potency and subsequent systemic toxicity make them prime candidates for targeted therapy, particularly in the form of antibody-drug conjugates (ADCs). Here we report a strategy to prepare stable and bioreversible conjugates of tubulysins to antibodies without loss of activity. A peptide trigger along with a quaternary ammonium salt linker connection to the tertiary amine of tubulysin provided ADCs that were potent . However, we observed metabolism of a critical acetate ester of the drug , resulting in diminished conjugate activity. We were able to circumvent this metabolic liability with the judicious choice of a propyl ether replacement. This modified tubulysin ADC was stable and effective against multidrug-resistant lymphoma cell lines and tumors.
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http://dx.doi.org/10.1021/acsmedchemlett.7b00243DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5641945PMC
October 2017

Cathepsin B Is Dispensable for Cellular Processing of Cathepsin B-Cleavable Antibody-Drug Conjugates.

Cancer Res 2017 12 18;77(24):7027-7037. Epub 2017 Oct 18.

Genentech, Inc., South San Francisco, California.

Antibody-drug conjugates (ADC) are designed to selectively bind to tumor antigens via the antibody and release their cytotoxic payload upon internalization. Controllable payload release through judicious design of the linker has been an early technological milestone. Here, we examine the effect of the protease-cleavable valine-citrulline [VC(S)] linker on ADC efficacy. The VC(S) linker was designed to be cleaved by cathepsin B, a lysosomal cysteine protease. Surprisingly, suppression of cathepsin B expression via CRISPR-Cas9 gene deletion or shRNA knockdown had no effect on the efficacy of ADCs with VC(S) linkers armed with a monomethyl auristatin E (MMAE) payload. Mass spectrometry studies of payload release suggested that other cysteine cathepsins can cleave the VC(S) linker. Also, ADCs with a nonprotease-cleavable enantiomer, the VC(R) isomer, mediated effective cell killing with a cysteine-VC(R)-MMAE catabolite generated by lysosomal catabolism. Based on these observations, we altered the payload to a pyrrolo[2,1-c][1,4]benzodiazepine dimer (PBD) conjugate that requires linker cleavage in order to bind its DNA target. Unlike the VC-MMAE ADCs, the VC(S)-PBD ADC is at least 20-fold more cytotoxic than the VC(R)-PBD ADC. Our findings reveal that the VC(S) linker has multiple paths to produce active catabolites and that antibody and intracellular targets are more critical to ADC efficacy. These results suggest that protease-cleavable linkers are unlikely to increase the therapeutic index of ADCs and that resistance based on linker processing is improbable. .
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http://dx.doi.org/10.1158/0008-5472.CAN-17-2391DOI Listing
December 2017

Modulating Therapeutic Activity and Toxicity of Pyrrolobenzodiazepine Antibody-Drug Conjugates with Self-Immolative Disulfide Linkers.

Mol Cancer Ther 2017 05 21;16(5):871-878. Epub 2017 Feb 21.

Genentech, Inc., South San Francisco, California.

A novel disulfide linker was designed to enable a direct connection between cytotoxic pyrrolobenzodiazepine (PBD) drugs and the cysteine on a targeting antibody for use in antibody-drug conjugates (ADCs). ADCs composed of a cysteine-engineered antibody were armed with a PBD using a self-immolative disulfide linker. Both the chemical linker and the antibody site were optimized for this new bioconjugation strategy to provide a highly stable and efficacious ADC. This novel disulfide ADC was compared with a conjugate containing the same PBD drug, but attached to the antibody via a peptide linker. Both ADCs had similar efficacy in mice bearing human tumor xenografts. Safety studies in rats revealed that the disulfide-linked ADC had a higher MTD than the peptide-linked ADC. Overall, these data suggest that the novel self-immolative disulfide linker represents a valuable way to construct ADCs with equivalent efficacy and improved safety. .
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http://dx.doi.org/10.1158/1535-7163.MCT-16-0641DOI Listing
May 2017

An anti-CD3/anti-CLL-1 bispecific antibody for the treatment of acute myeloid leukemia.

Blood 2017 02 1;129(5):609-618. Epub 2016 Dec 1.

Research and Early Development, Genentech, South San Francisco, CA.

Acute myeloid leukemia (AML) is a major unmet medical need. Most patients have poor long-term survival, and treatment has not significantly changed in 40 years. Recently, bispecific antibodies that redirect the cytotoxic activity of effector T cells by binding to CD3, the signaling component of the T-cell receptor, and a tumor target have shown clinical activity. Notably, blinatumomab is approved to treat relapsed/refractory acute lymphoid leukemia. Here we describe the design, discovery, pharmacologic activity, pharmacokinetics, and safety of a CD3 T cell-dependent bispecific (TDB) full-length human IgG1 therapeutic antibody targeting CLL-1 that could potentially be used in humans to treat AML. CLL-1 is prevalent in AML and, unlike other targets such as CD33 and CD123, is not expressed on hematopoietic stem cells providing potential hematopoietic recovery. We selected a high-affinity monkey cross-reactive anti-CLL-1 arm and tested several anti-CD3 arms that varied in affinity, and determined that the high-affinity CD3 arms were up to 100-fold more potent in vitro. However, in mouse models, the efficacy differences were less pronounced, probably because of prolonged exposure to TDB found with lower-affinity CD3 TDBs. In monkeys, assessment of safety and target cell depletion by the high- and low-affinity TDBs revealed that only the low-affinity CD3/CLL1 TDB was well tolerated and able to deplete target cells. Our data suggest that an appropriately engineered CLL-1 TDB could be effective in the treatment of AML.
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http://dx.doi.org/10.1182/blood-2016-08-735365DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5290988PMC
February 2017

Targeting LGR5+ cells with an antibody-drug conjugate for the treatment of colon cancer.

Sci Transl Med 2015 Nov;7(314):314ra186

Research and Early Development, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA.

Cancer stem cells (CSCs) are hypothesized to actively maintain tumors similarly to how their normal counterparts replenish differentiated cell types within tissues, making them an attractive therapeutic target for the treatment of cancer. Because most CSC markers also label normal tissue stem cells, it is unclear how to selectively target them without compromising normal tissue homeostasis. We evaluated a strategy that targets the cell surface leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5), a well-characterized tissue stem cell and CSC marker, with an antibody conjugated to distinct cytotoxic drugs. One antibody-drug conjugate (ADC) demonstrated potent tumor efficacy and safety in vivo. Furthermore, the ADC decreased tumor size and proliferation, translating to improved survival in a genetically engineered model of intestinal tumorigenesis. These data demonstrate that ADCs can be leveraged to exploit differences between normal and cancer stem cells to successfully target gastrointestinal cancers.
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http://dx.doi.org/10.1126/scitranslmed.aac7433DOI Listing
November 2015

An anti-B7-H4 antibody-drug conjugate for the treatment of breast cancer.

Mol Pharm 2015 Jun 23;12(6):1717-29. Epub 2015 Apr 23.

B7-H4 has been implicated in cancers of the female reproductive system and investigated for its possible use as a biomarker for cancer, but there are no preclinical studies to demonstrate that B7-H4 is a molecular target for therapeutic intervention of cancer. We provide evidence that the prevalence and expression levels of B7-H4 are high in different subtypes of breast cancer and that only a few normal tissues express B7-H4 on the cell membrane. These profiles of low normal expression and upregulation in cancer provide an opportunity for the use of antibody-drug conjugates (ADCs), cytotoxic drugs chemically linked to antibodies, for the treatment of B7-H4 positive cancers. We have developed an ADC specific to B7-H4 that uses a linker drug consisting of a potent antimitotic, monomethyl auristatin E (MMAE), linked to engineered cysteines (THIOMAB) via a protease labile linker. We will refer to ADCs that use the THIOMAB format as TDCs to help distinguish the format from standard MC-vc-MMAE ADCs that are conjugated to the interchain disulfide bonds. Anti-B7-H4 (h1D11)-MC-vc-PAB-MMAE (h1D11 TDC) produced durable tumor regression in cell line and patient-derived xenograft models of triple-negative breast cancer. It also binds rat B7-H4 with similar affinity to human and allowed us to test for target dependent toxicity in rats. We found that our anti-B7-H4 TDC has toxicity findings similar to untargeted TDC. Our results validate B7-H4 as an ADC target for breast cancer and support the possible use of this TDC in the treatment of B7-H4(+) breast cancer.
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http://dx.doi.org/10.1021/mp5007745DOI Listing
June 2015

A Novel Anti-CD22 Anthracycline-Based Antibody-Drug Conjugate (ADC) That Overcomes Resistance to Auristatin-Based ADCs.

Clin Cancer Res 2015 Jul 3;21(14):3298-306. Epub 2015 Apr 3.

Research and Early Development, Genentech Inc., South San Francisco, California.

Purpose: We are interested in identifying mechanisms of resistance to the current generation of antibody-drug conjugates (ADC) and developing ADCs that can overcome this resistance.

Experimental Design: Pinatuzumab vedotin (anti-CD22-vc-MMAE) and polatuzumab vedotin (anti-CD79b-vc-MMAE) are ADCs that contain the microtubule inhibitor monomethyl auristatin E (MMAE) attached to the antibody by the protease-cleavable linker maleimidocaproyl-valine-citrulline-p-aminobenzoyloxycarbonyl (MC-vc-PAB). Early clinical trial data suggest that these ADCs have promising efficacy for the treatment of non-Hodgkin lymphoma (NHL); however, some patients do not respond or become resistant to the ADCs. Anthracyclines are very effective in NHL, but ADCs containing the anthracycline doxorubicin were not clinically efficacious probably due to the low drug potency and inadequate linker technology. The anthracycline analogue PNU-159682 is thousands of times more cytotoxic than doxorubicin, so we used it to develop a new class of ADCs. We used the same MC-vc-PAB linker and antibody in pinatuzumab vedotin but replaced the MMAE with a derivative of PNU-159682 to make anti-CD22-NMS249 and tested it for in vivo efficacy in xenograft tumors resistant to MMAE-based ADCs.

Results: We derived cell lines from in vivo xenograft tumors that were made resistant to anti-CD22-vc-MMAE and anti-CD79b-vc-MMAE. We identified P-gp (ABCB1/MDR1) as the major driver of resistance to the vc-MMAE-based conjugates. Anti-CD22-NMS249 was at least as effective as anti-CD22-vc-MMAE in xenograft models of the parental cell lines and maintained its efficacy in the resistant cell lines.

Conclusions: These studies provide proof of concept for an anthracycline-based ADC that could be used to treat B-cell malignancies that are resistant to vc-MMAE conjugates.
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http://dx.doi.org/10.1158/1078-0432.CCR-14-2035DOI Listing
July 2015

The cryptophycins as potent payloads for antibody drug conjugates.

Bioorg Med Chem Lett 2015 Feb 2;25(4):864-8. Epub 2015 Jan 2.

Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, United States.

The cryptophycins are a potent class of cytotoxic agents that were evaluated as antibody drug conjugate (ADC) payloads. Free cryptophycin analog 1 displayed cell activity an order of magnitude more potent than approved ADC payloads MMAE and DM1. This potency increase was also reflected in the activity of the cryptophycin ADCs, attached via a either cleavable or non-cleavable linker.
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http://dx.doi.org/10.1016/j.bmcl.2014.12.070DOI Listing
February 2015

DCDT2980S, an anti-CD22-monomethyl auristatin E antibody-drug conjugate, is a potential treatment for non-Hodgkin lymphoma.

Mol Cancer Ther 2013 Jul 18;12(7):1255-65. Epub 2013 Apr 18.

Genentech Research and Early Development, 1 DNA Way, South San Francisco, CA 94080, USA.

Antibody-drug conjugates (ADC), potent cytotoxic drugs linked to antibodies via chemical linkers, allow specific targeting of drugs to neoplastic cells. We have used this technology to develop the ADC DCDT2980S that targets CD22, an antigen with expression limited to B cells and the vast majority of non-Hodgkin lymphomas (NHL). DCDT2980S consists of a humanized anti-CD22 monoclonal IgG1 antibody with a potent microtubule-disrupting agent, monomethyl auristatin E (MMAE), linked to the reduced cysteines of the antibody via a protease cleavable linker, maleimidocaproyl-valine-citrulline-p-aminobenzoyloxycarbonyl (MC-vc-PAB). We describe the efficacy, safety, and pharmacokinetics of DCDT2980S in animal models to assess its potential as a therapeutic for the treatment of B-cell malignancies. We did not find a strong correlation between in vitro or in vivo efficacy and CD22 surface expression, nor a correlation of sensitivity to free drug and in vitro potency. We show that DCDT2980S was capable of inducing complete tumor regression in xenograft mouse models of NHL and can be more effective than rituximab plus combination chemotherapy at drug exposures that were well tolerated in cynomolgus monkeys. These results suggest that DCDT2980S has an efficacy, safety, and pharmacokinetics profile that support potential treatment of NHL.
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http://dx.doi.org/10.1158/1535-7163.MCT-12-1173DOI Listing
July 2013

FcRL5 as a target of antibody-drug conjugates for the treatment of multiple myeloma.

Mol Cancer Ther 2012 Oct 17;11(10):2222-32. Epub 2012 Jul 17.

Genentech Research and Early Development. 1 DNA Way, South San Francisco, CA 94080, USA.

Fc receptor-like 5 (FcRL5/FcRH5/IRTA2/CD307) is a surface protein expressed selectively on B cells and plasma cells. We found that FcRL5 was expressed at elevated levels on the surface of plasma cells from the bone marrow of patients diagnosed with multiple myeloma. This prevalence in multiple myeloma and narrow pattern of normal expression indicate that FcRL5 could be a target for antibody-based therapies for multiple myeloma, particularly antibody-drug conjugates (ADC), potent cytotoxic drugs linked to antibodies via specialized chemical linkers, where limited expression on normal tissues is a key component to their safety. We found that FcRL5 is internalized upon antibody binding, indicating that ADCs to FcRL5 could be effective. Indeed, we found that FcRL5 ADCs were efficacious in vitro and in vivo but the unconjugated antibody was not. The two most effective consisted of our anti-FcRL5 antibody conjugated through cysteines to monomethylauristatin E (MMAE) by a maleimidocaproyl-valine-citrulline-p-aminobenzyloxycarbonyl (MC-vcPAB) linker (anti-FcRL5-MC-vcPAB-MMAE) or conjugated via lysines to the maytansinoid DM4 through a disulfide linker (anti-FcRL5-SPDB-DM4). These two ADCs were highly effective in vivo in combination with bortezomib or lenalidomide, drugs in use for the treatment of multiple myeloma. These data show that the FcRL5 ADCs described herein show promise as an effective treatment for multiple myeloma.
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http://dx.doi.org/10.1158/1535-7163.MCT-12-0087DOI Listing
October 2012

The successes and limitations of preclinical studies in predicting the pharmacodynamics and safety of cell-surface-targeted biological agents in patients.

Br J Pharmacol 2012 Jul;166(5):1600-2

Genentech Research and Early Development, South San Francisco, CA, USA.

To improve drug development outcomes, it is important to review when preclinical pharmacodynamic and safety models have successfully predicted human responses and when they have not. In a recent issue of the BJP, Bugelski and Martin examined the concordance between preclinical and human data for biopharmaceuticals targeted to cell-surface proteins. The cases are interesting and several trends emerge. The pharmacodynamics of biopharmaceuticals in non-human primates is largely predictive; the use of surrogates in rodents may be similarly predictive, allowing for more conservative use of non-human primates. While overall concordance of preclinical toxicology data and clinical safety was poor, this is largely a reflection of the immunomodulatory biology of the majority of the biopharmaceuticals evaluated. The examples show that adverse effects in animals that were the result of direct and/or exaggerated pharmacology were modelled well, but that specific infections or other indirect outcomes of immunomodulation, along with cytokine-related events, were not modelled well in preclinical studies.
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http://dx.doi.org/10.1111/j.1476-5381.2012.01916.xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3419903PMC
July 2012

CD40 pathway activation status predicts response to CD40 therapy in diffuse large B cell lymphoma.

Sci Transl Med 2011 Mar;3(74):74ra22

Department of Biostatistics, Genentech Inc., South San Francisco, CA 94080, USA.

The primary function of B cells, critical components of the adaptive immune response, is to produce antibodies against foreign antigens, as well as to perform isotype class switching, which changes the heavy chain of an antibody so that it can interact with different repertoires of effector cells. CD40 is a member of the tumor necrosis factor superfamily of cell surface receptors that transmits survival signals to B cells. In contrast, in B cell cancers, stimulation of CD40 signaling results in a heterogeneous response in which cells can sometimes undergo cell death in response to treatment, depending on the system studied. We found an association between sensitivity to CD40 stimulation and mutation of the tumor suppressor p53 in a panel of non-Hodgkin's lymphoma cell lines. Consistent with p53's tumor suppressor role, we found that higher levels of intrinsic DNA damage and increased proliferation rates, as well as higher levels of BCL6, a transcriptional repressor proto-oncogene, were associated with sensitivity to CD40 stimulation. In addition, CD40 treatment-resistant cell lines were sensitized to CD40 stimulation after the introduction of DNA-damaging agents. Using gene expression analysis, we also showed that resistant cell lines exhibited a preexisting activated CD40 pathway and that an mRNA expression signature comprising CD40 target genes predicted sensitivity and resistance to CD40-activating agents in cell lines and mouse xenograft models. Finally, the gene signature predicted tumor shrinkage and progression-free survival in patients with diffuse large B cell lymphoma treated with dacetuzumab, a monoclonal antibody with partial CD40 agonist activity. These data show that CD40 pathway activation status may be useful in predicting the antitumor activity of CD40-stimulating therapeutic drugs.
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http://dx.doi.org/10.1126/scitranslmed.3001620DOI Listing
March 2011

Investigational antibody-drug conjugates for hematological malignancies.

Expert Opin Investig Drugs 2011 Jan 11;20(1):75-85. Epub 2010 Dec 11.

Genentech, Inc., Department of Translational Oncology, 1 DNA way, Mail Stop 72A, South San Francisco 94080, CA, USA.

Importance Of The Field: Antibody-drug conjugates (ADCs) consist of potent cytotoxic drugs linked to antibodies via chemical linkers. ADCs facilitate the specific targeting of drugs to neoplastic cells. This technology is showing efficacy with manageable toxicity for the treatment of hematological malignancies.

Areas Covered In This Review: ADCs for the treatment of hematological malignancies are in pre-clinical and early clinical trials. This review describes these ADCs in detail and explores the challenges of optimizing the use of this technology.

What The Reader Will Gain: The reader should understand that, although ADCs are conceptually simple, the application of this idea to practice has not been straightforward, and the challenges of developing ADCs include identifying targets with appropriate expression profiles and biology, developing successful linker chemistries, and the selection of a potent cytotoxic drug.

Take Home Message: Hematological malignancies are particularly suited to the development of ADC therapeutics as their surface proteins are well characterized, and the consequences of expression of the target in the normal tissue like the bone marrow results in manageable toxicities since, in many cases, the normal tissue can regenerate. While this technology is complex, the ADCs for hematological malignancies currently in clinical use show great promise.
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http://dx.doi.org/10.1517/13543784.2011.539557DOI Listing
January 2011

In vivo effects of targeting CD79b with antibodies and antibody-drug conjugates.

Mol Cancer Ther 2009 Oct 6;8(10):2937-46. Epub 2009 Oct 6.

Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA.

Antibodies directed against B cells are in use for the treatment of non-Hodgkin's lymphoma and autoimmune disorders. The B-cell-restricted surface antigen CD79b, a signaling component of the B-cell receptor, has been shown as a promising antibody target in mouse efficacy models of systemic lupus erythematosus. Anti-CD79b antibody-drug conjugates (ADC), cytotoxic drugs linked through specialized chemical linkers to antibodies, are effective in mouse xenograft models of non-Hodgkin's lymphoma. We were interested in evaluating the systemic effects of anti-CD79b antibodies and ADCs in normal animals as a step toward the development of these molecules as therapeutics. As we were unable to identify any cell surface binding anti-human CD79b antibodies that were cross-reactive to other species, we developed an antibody to cynomolgus monkey (Macaca fascicularis) CD79b (anti-cyCD79b). The anti-cynomolgus antibody, anti-cyCD79b (10D10), and the maytansine (tubulin inhibitor)-conjugated ADC, anti-cyCD79b (10D10)-MCC-DM1, were administered to cynomolgus monkeys at approximately 30 mg/kg (6,000 microg DM1/m(2)) for two doses 3 weeks apart. Anti-cyCD79b and anti-cyCD79b-MCC-DM1 resulted in peripheral blood B-cell depletion of approximately 65% and approximately 94%, respectively. In addition, anti-cyCD79b-MCC-DM1 resulted in near-complete absence of splenic germinal centers, an observation supporting an effect on dividing B cells. Both molecules were well tolerated, with minimal findings for the antibody and findings for the ADC limited to the lymphoid and hematopoietic systems, liver, and peripheral nerves. These preclinical data suggest that targeting CD79b with antibodies or ADCs may provide safe and effective therapies for B-cell malignancies and autoimmune diseases.
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http://dx.doi.org/10.1158/1535-7163.MCT-09-0369DOI Listing
October 2009

Therapeutic potential of an anti-CD79b antibody-drug conjugate, anti-CD79b-vc-MMAE, for the treatment of non-Hodgkin lymphoma.

Blood 2009 Sep 24;114(13):2721-9. Epub 2009 Jul 24.

Genentech Inc, South San Francisco, CA 94080, USA.

Here we describe the generation of an antibody-drug conjugate (ADC) consisting of a humanized anti-CD79b antibody that is conjugated to monomethylauristatin E (MMAE) through engineered cysteines (THIOMABs) by a protease cleavable linker. By using flow cytometry, we detected the surface expression of CD79b in almost all non-Hodgkin lymphoma (NHL) and chronic lymphocytic leukemia patients, suggesting that anti-CD79b-vcMMAE could be widely used in these malignancies. By using NHL cell lines to simulate a patient population we discovered that a minimal cell-surface expression level of CD79b was required for in vitro activity. Within the subpopulation of cell lines above this minimal threshold, we found that sensitivity to free MMAE, mutation of cancer genes, and cell doubling time were poorly correlated with in vitro activity; however, the expression level of BCL-XL was correlated with reduced sensitivity to anti-CD79b-vcMMAE. This observation was supported by in vivo data showing that a Bcl-2 family inhibitor, ABT-263, strikingly enhanced the activity of anti-CD79b-vcMMAE. Furthermore, anti-CD79b-vcMMAE was significantly more effective than a standard-of-care regimen, R-CHOP (ie, rituximab with a single intravenous injection of 30 mg/kg cyclophosphamide, 2.475 mg/kg doxorubicin, 0.375 mg/kg vincristine, and oral dosing of 0.15 mg/kg prednisone once a day for 5 days), in 3 xenograft models of NHL. Together, these data suggest that anti-CD79b-vcMMAE could be broadly efficacious for the treatment of NHL.
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http://dx.doi.org/10.1182/blood-2009-02-205500DOI Listing
September 2009

Toward an effective targeted chemotherapy for multiple myeloma.

Clin Cancer Res 2009 Jun 9;15(12):3906-7. Epub 2009 Jun 9.

Genentech Inc, South San Francisco, California 94080, USA.

Antibody-drug conjugates (ADCs), cytotoxic drugs chemically linked to antibodies, provide a means to increase the effectiveness of chemotherapy by targeting the drug to neoplastic cells. Anti-CD138 ADCs show promising preclinical efficacy for the treatment of multiple myeloma; however, the safety aspects of targeting CD138 have yet to be explored.
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http://dx.doi.org/10.1158/1078-0432.CCR-09-0572DOI Listing
June 2009

Antibody-drug conjugates for the treatment of non-Hodgkin's lymphoma: target and linker-drug selection.

Cancer Res 2009 Mar 3;69(6):2358-64. Epub 2009 Mar 3.

Genentech, Inc., South San Francisco, California, USA.

Antibody-drug conjugates (ADC), potent cytotoxic drugs covalently linked to antibodies via chemical linkers, provide a means to increase the effectiveness of chemotherapy by targeting the drug to neoplastic cells while reducing side effects. Here, we systematically examine the potential targets and linker-drug combinations that could provide an optimal ADC for the treatment for non-Hodgkin's lymphoma. We identified seven antigens (CD19, CD20, CD21, CD22, CD72, CD79b, and CD180) for potential treatment of non-Hodgkin's lymphoma with ADCs. ADCs with cleavable linkers mediated in vivo efficacy via all these targets; ADCs with uncleavable linkers were only effective when targeted to CD22 and CD79b. In target-independent safety studies in rats, the uncleavable linker ADCs showed reduced toxicity, presumably due to the reduced release of free drug or other toxic metabolites into the circulation. Thus, our data suggest that ADCs with cleavable linkers work on a broad range of targets, and for specific targets, ADCs with uncleavable linkers provide a promising opportunity to improve the therapeutic window for ADCs in humans.
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http://dx.doi.org/10.1158/0008-5472.CAN-08-2250DOI Listing
March 2009

Antibody-drug conjugates targeted to CD79 for the treatment of non-Hodgkin lymphoma.

Blood 2007 Jul 20;110(2):616-23. Epub 2007 Mar 20.

Department of Translational Oncology, Genentech, South San Francisco, CA, USA.

Targeting cytotoxic drugs to cancer cells using antibody-drug conjugates (ADCs), particularly those with stable linkers between the drug and the antibody, could be an effective cancer treatment with low toxicity. However, for stable-linker ADCs to be effective, they must be internalized and degraded, limiting potential targets to surface antigens that are trafficked to lysosomes. CD79a and CD79b comprise the hetrodimeric signaling component of the B-cell receptor, and are attractive targets for the use of ADCs because they are B-cell-specific, expressed in non-Hodgkin lymphomas (NHL), and are trafficked to a lysosomal-like compartment as part of antigen presentation. We show here that the stable-linker ADCs anti-CD79b-MCC-DM1 and anti-CD79b-MC-MMAF are capable of target-dependent killing of nonHodgkin lymphoma cell lines in vitro. Further, these 2 ADCs are equally effective as low doses in xenograft models of follicular, mantle cell, and Burkitt lymphomas, even though several of these cell lines express relatively low levels of CD79b in vivo. In addition, we demonstrate that anti-CD79b ADCs were more effective than anti-CD79a ADCs and that, as hypothesized, anti-CD79b antibodies downregulated surface B-cell receptor and were trafficked to the lysosomal-like major histocompatibility complex class II-positive compartment MIIC. These results suggest that anti-CD79b-MCC-DM1 and anti-CD79b-MC-MMAF are promising therapeutics for the treatment of NHL.
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http://dx.doi.org/10.1182/blood-2007-01-066704DOI Listing
July 2007

Expression pattern of the human FcRH/IRTA receptors in normal tissue and in B-chronic lymphocytic leukemia.

Int Immunol 2006 Sep 18;18(9):1363-73. Epub 2006 Jul 18.

Department of Translational Oncology, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA.

A new family of Ig domain receptors referred to as the immune receptor translocation-associated (IRTA) proteins, FcR homologs (FcRHs) or FcR-like that are expressed in lymphoid cells has been recently described. RNA expression analysis suggests that FcRH1-5/IRTA1-5 are expressed exclusively in subsets of the B-cell compartment. We generated mAbs to FcRH1-5/IRTA1-5 and examined their protein expression pattern in normal tissue and in chronic lymphocytic leukemia (CLL) cells. Our data indicated that FcRH1-5/IRTA1-5 were expressed in B-cell sub-populations; however, in some cases, the protein was not expressed in the same B-cell populations as suggested by the RNA expression analysis. FcRH1/IRTA5 was expressed throughout the B-cell lineage starting at the pro-B-cell stage but was down-regulated in plasma cells. FcRH2/IRTA4 was expressed preferentially in memory B cells. FcRH3/IRTA3 was expressed at low levels in naive, germinal center (GC) and memory B cells but was also expressed in NK cells. FcRH4/IRTA1 was expressed in a sub-population of memory B cells associated with mucosal tissue. FcRH5/IRTA2 was expressed in mature B cells and memory B cells and down-regulated in GC cells and, unlike all other B-cell-specific markers, maintained its expression in plasma cells from tonsil, spleen and bone marrow. We examined the expression of FcRH1-5/IRTA1-5 on the surface of CLL cells and found a similar pattern of expression on CLL cells as in the normal mature B cells, except for FcRH3/IRTA3 which was up-regulated in CLL.
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http://dx.doi.org/10.1093/intimm/dxl069DOI Listing
September 2006