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Despite the recent progress, multiple myeloma (MM) is still essentially incurable and there is a need for additional effective treatments with good tolerability. RO7297089 is a novel bispecific BCMA/CD16A-directed innate cell engager (ICE

Introduction: Fc receptor-homolog 5 (FcRH5) is an immunoglobulin (Ig) domain-containing type I membrane protein that is expressed exclusively in the B-cell lineage. FcRH5 expression is retained in myeloma cells, with near 100% prevalence, and is elevated vs normal B cells. BFCR4350A is a humanized IgG-based T-cell-engaging bispecific antibody. Binding of BFCR4350A to the most membrane-proximal domain of FcRH5 on myeloma cells and to cluster of differentiation 3 (CD3) on T cells results in efficient immunological synapse formation and potent T-cell-directed killing of myeloma cells (Li, et al. Cancer Cell 2017). An ongoing Phase I dose-escalation study (GO39775; NCT03275103) is investigating the safety, activity, pharmacodynamics (PD) and pharmacokinetics of BFCR4350A monotherapy in patients (pts) with relapsed/refractory (R/R) multiple myeloma (MM). In Arm A, clinical activity was observed at the 3.6mg/20mg (step/target) dose level and above, and toxicity was manageable (Cohen, et al. ASH 2020). We present preliminary biomarker data that demonstrate the mode of action (MOA) of BFCR4350A, provide support for Cycle (C) 1 step-up dosing, and offer preliminary insights into markers that may predict response. Methods: In Arm A, R/R MM pts receive BFCR4350A by intravenous infusion in 21-day cycles. In C1, a single step-up dosing approach is used to mitigate the risk for cytokine release syndrome (CRS), with the step dose given on C1 Day (D) 1 and the target dose given on C1D8. The target dose is then administered on D1 of each subsequent cycle. PD changes in peripheral blood (PB) are assessed at baseline and at multiple time points within C1 by whole blood flow cytometry, plasma cytokine electrochemiluminescence and digital ELISA. Tumor biomarkers are assessed at baseline and pre-C2 by bone marrow (BM) biopsy dual CD138/CD8 immunohistochemistry staining and BM aspirate flow cytometry. The clinical cut-off date used for the current analyses was April 13, 2020. Results: At cut-off, all pts in Arm A (n=51) were biomarker evaluable. FcRH5 expression on myeloma cells was detected in all pts. Dose-dependent PD changes in PB were observed 24-192 hrs after the C1D1 infusion. Variable reduction in circulating T cells was observed 24 hrs after the 0.3-1.8mg C1D1 doses, while consistent reduction was observed after the 3.6mg C1D1 dose, with recovery by C1D8 (192 hrs). T-cell activation was detected 24 hrs post-infusion by upregulation of CD69 in CD8 and CD4 T cells and elevation of IFN-γ in plasma (median increase of ~150-fold from baseline), while T-cell proliferation (Ki67+) peaked by C1D8. At the 3.6mg C1D1 dose, CD8 T-cell activation and proliferation were up to 20-fold higher than at baseline. Minimal elevation of IL-6 was observed post-infusion in pts who received doses below 3.6mg on C1D1, while more consistent increases (≥100pg/ml) were observed in pts who received 3.6mg. IL-6 levels peaked within 24 hrs of the C1D1 dose and the kinetics of IL-6 increase were associated with dose and risk for CRS. Step-up dosing mitigated the risk for severe CRS, as evidenced by lower IL-6 levels after the C1D8 target dose compared to the 3.6mg C1D1 step dose in 27/33 (82%) pts (see Cohen, et al. ASH 2020 for corresponding clinical data). Preliminary data suggest that pts who respond to BFCR4350A have more pronounced T-cell expansion in PB, irrespective of baseline CD8 T-cell levels during the first week of C1. Analysis of the subset of pts with paired BM biopsies (n=19 pts) revealed that levels of CD8+ tumor infiltrating T-cells (TILs) were higher in responding pts than in non-responding pts at the end of C1. Conclusions: In this study, we demonstrated that early PD changes in T-cell activation, proliferation, and cytokine production confirm the MOA of BFCR4350A and support C1 step-up dosing for CRS mitigation in R/R MM. Early data suggest that at the end of C1, higher peripheral CD8 T-cell expansion and TILs are observed in responding pts than in non-responding pts. Additional analyses are ongoing to establish BFCR4350A response predictors and to better characterize the populations that are likely to benefit. Updated data will be presented. Disclosures Nakamura: Genentech, Inc.: Current Employment; F. Hoffmann-La Roche: Current equity holder in publicly-traded company. Lear:F. Hoffmann-La Roche: Current equity holder in publicly-traded company; Genentech, Inc.: Current Employment. Wilson:Genentech, Inc.: Current Employment. Koeppen:Genentech, Inc./ F. Hoffmann-La Roche: Current Employment; F. Hoffmann-La Roche, Pliant Therapeutics, Allogene, Jounce: Current equity holder in publicly-traded company. Vaze:Genentech, Inc./ F. Hoffmann-La Roche: Current Employment, Current equity holder in publicly-traded company. Trudel:Takeda: Honoraria; Sanofi: Honoraria; GSK: Consultancy, Honoraria, Research Funding; Genentech, Inc.: Research Funding; BMS: Consultancy, Honoraria, Research Funding; Karyopharm: Honoraria; AstraZeneca: Honoraria; Pfizer: Honoraria, Research Funding; Amgen: Consultancy, Research Funding; Janssen: Honoraria, Research Funding. Spencer:Amgen, Celgene, Haemalogix, Janssen, Servier and Takeda: Research Funding; AbbVie, Amgen, Celgene, Haemalogix, Janssen, Sanofi, SecuraBio, Specialised Therapeutics Australia, Servier and Takeda: Honoraria; AbbVie, Celgene, Haemalogix, Janssen, Sanofi, SecuraBio, Specialised Therapeutics Australia, Servier and Takeda: Consultancy; Celgene, Janssen and Takeda: Speakers Bureau. Harrison:Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; GSK: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; F. Hoffmann-La Roche: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Patents & Royalties: wrt panobinostat; Janssen: Honoraria; BMS: Consultancy, Honoraria; CRISPR Therapeutics: Consultancy, Honoraria; Haemalogix: Consultancy; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen-Cilag: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Cohen:Novartis: Other: Patents/Intellectual property licensed, Research Funding; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; Takeda,: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees; Kite Pharma: Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Genentech/Roche: Membership on an entity's Board of Directors or advisory committees. Fine:Genentech, Inc.: Current Employment; F. Hoffmann-La Roche: Current equity holder in publicly-traded company. Li:Genentech, Inc./ F. Hoffmann-La Roche: Current Employment. Cooper:Genentech, Inc./ F. Hoffmann-La Roche: Current Employment, Current equity holder in publicly-traded company. Sumiyoshi:Genentech, Inc.: Current Employment, Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months. OffLabel Disclosure: BFCR4350A is a humanized IgG-based T-cell-engaging bispecific antibody that targets the most membrane-proximal domain of FcRH5 on myeloma cells and CD3 on T cells. Dual binding facilitates efficient immunological synapse formation, resulting in T-cell activation and killing of myeloma cells. BFCR4350A is an investigational agent.

Treatment options for metastatic urothelial bladder cancer (UBC) are limited. Mutational complexity is known to be high in UBC and may correlate with increased immunogenicity. MPDL3280A, a human PD-L1 monoclonal antibody containing an engineered Fc-domain designed to promote a Th1-driven response, has demonstrated a RECIST response rate of 43% in diagnostically selected, pretreated patients with UBC. A total of 68 patients (67 with efficacy evaluable) were enrolled in the UBC cohort of the Phase I study; 45% were PD-L1 IHC diagnostic positive as defined by expression of PD-L1 on ≥ 5% of tumor-infiltrating immune cells. In the prescreened UBC population, the prevalence of PD-L1-positive patients was 27%. Comprehensive gene expression analyses of UBC tumors were conducted to interrogate the tumor immune microenvironment in PD-L1-positive tumors and to identify potential mechanisms associated with response or resistance to MPDL3280A. In this study, PD-L1-positive tumors exhibited a high prevalence of gene expression markers associated with T-effector cells (Teff), including perforin, IFNγ, CD8A, granzyme B, granzyme A and EOMES. Additionally, a low baseline signature of genes associated with myeloid cell markers, including IL1B and IL8, appeared to be statistically significantly associated (P

First two authors contributed equally Last two authors contributed equally Recent studies have shown that ex vivo propagation of normal tissues or patient-derived tumor cells in presence of irradiated fibroblast feeder cells and ROCK inhibitor can rapidly establish conditionally reprogramed cells (CRCs). In case of normal tissues, the induction of CRCs was reversible when the ROCK inhibitor and the feeder cells were removed, resulting in CRCs differentiating to its tissue origin (Liu et al.2012). Previous publications suggested that the establishment of such cell models provides new strategies to understand acquired resistance during treatment (Crystal et al 2015) and to predict treatment response (Liu et al. 2014). However, gene expression modulations and genomic drifting during the establishment of CRC propagation have not been thoroughly studied. The primary goal of this study is to molecularly characterize alterations between the original tumor tissues and the derived models growing with or without ROCK inhibitor. Understanding in-depth molecular fluctuations in this patient-derived ex vivo system will facilitate its appropriate use for tumor biology experimentation. Herein, tumors from prostate cancer and breast cancer patients were surgical removed and cryopreserved at the clinical site then processed and cultured as previously described (Liu et al. 2012). Gene expression profiling and next-generation sequencing were carried out on the original tumor tissues and cellular models passaged during the CRC propagation in the presence or absence of ROCK inhibitor. Gene expression analysis of the prostate cancer cells and the breast cancer cells were carried out using a 93-gene prostate cancer-focused Fluidigm panel and a 800 gene NanoString breast cancer-focused panel, respectively. Cancer hotspot mutations were analyzed using the Ion Torrent Cancer Hotspot v2 NGS assay. Through aforementioned genomic and transcriptomic interrogations, we demonstrated the extent of indication-relevant gene expression modulation during establishment and propagation of these cells. We also characterize cancer hotspot mutations in the primary tumor cells and the stability of those mutations during ex vivo propagation. These results should begin to inform the appropriate use of the CRC model for tumor biology experimentation. Citation Format: Jessica Li, Bonnie Liu, Rin Nakamura, Heidi Savage, Shoji Ikeda, Timothy Wilson, Teiko Sumiyoshi, Garret Hampton, Lukas Amler, Mark Lackner, Shih-Min A. Huang, Walter C. Darbonne. Gene expression and genomic drift comparative analysis between patient-derived conditionally reprogrammed cells and original tumors. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4257.

Accurately measuring the expression of genes in formalin-fixed paraffin embedded (FFPE) tumor tissues has long been a struggle due to the inherent degradation of RNA isolated from these materials. Accurate quantification of gene expression levels in FFPE samples can enable the testing of biomarker hypotheses in the clinic and can potentially be used for patient stratification or selection in clinical trials. Platforms such as Fluidigm, Nanostring and microarrays are currently the high-throughput technologies utilized. Each of these platforms has different drawbacks and challenges such as lack of sensitivity, reproducibility or dynamic range when working with degraded FFPE samples. Currently, whole transcriptome RNA sequencing (RNA-Seq) is the only platform that offers a truly high-throughput, sensitive, and reproducible method to accurately quantify mRNA levels in RNA derived from FFPE samples. RNA-Seq, however has not yet been widely evaluated and adapted for use with degraded FFPE samples. Here we report the direct comparison of whole transcriptome RNA-Seq with two platforms that are currently compatible with FFPE derived RNA, Fluidigm and Nanostring, to determine the accuracy and feasibility of using this technology on degraded RNA. Utilizing a collection of matched fresh frozen (FF) and FFPE samples we analyzed gene expression using all three platforms to allow for a direct evaluation of each technology. By comparing the results to the matching FF sample, we were able to determine the accuracy and sensitivity of each platform when using degraded FFPE derived RNA. By titrating down the input of FFPE RNA into the RNA-Seq library prep we were also able to define the optimal input of FFPE RNA needed to accurately and reproducibly quantify gene expression. This work allows for a systematic comparison of different gene expression platforms for their use with degraded FFPE RNA. Citation Format: Erica B. Schleifman, Maipelo Motlhabi, Craig Cummings, Rin Nakamura, Linda Bosch, Rajesh Patel, An Do, Andrew Watson, Thomas Sandmann, Walter Darbonne, Ian McCaffery, Eric Peters, Rajiv Raja. Comparison of gene expression platforms: RNA-Seq, Fluidigm, and Nanostring. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4901. doi:10.1158/1538-7445.AM2015-4901

PD-L1 expressed in the tumor microenvironment regulates Th1 immune responses and mediates cancer immune evasion through interactions with PD-1 or B7.1 receptors on activated T cells. MPDL3280A, an engineered human monoclonal antibody, targets PD-L1 and inhibits its function. To identify immunologic predictive and pharmacodynamic biomarkers of MPDL3280A treatment, we performed a comprehensive analysis of tumors and blood samples collected at baseline and/or on treatment from ≈280 patients with locally advanced or metastatic solid tumors, including NSCLC, RCC, melanoma and bladder cancer. Regardless of tumor type, clinical responses were characterized by PD-L1 expression, the presence of markers of T cell activation (Th1 gene signature and CTLA4), and the absence of fractalkine at baseline in the tumor microenvironment. Elevated baseline expression of IFN-γ and IFN-γ-inducible genes (e.g., IDO1 and CXCL9) was associated with MPDL3280A response in melanoma but not NSCLC or RCC. On treatment, responding tumors showed increased infiltration of Th1-dominant immune infiltrate and evidence of adaptive PD-L1 up-regulation. In contrast, progressing tumors displayed the following patterns of tumor-infiltrating lymphocytes (TILs) and PD-L1 expression: (1) few/no TILs and absent PD-L1 expression (immunologic ignorance), (2) TILs present with minimal/no PD-L1 expression (non-functional immune responses), or (3) TILs residing solely around the tumor cell mass outer edge (excluded infiltrate), suggesting that resistance to MPDL3280A may be associated with impaired T cell trafficking and/or function. Profiling of ≈180 circulating biomarkers revealed that plasma concentrations of IL-18 and interferon-inducible T cell alpha chemoattractant (ITAC) increased in all patients following MPDL3280A treatment, representing a pharmacodynamic measurement of PD-L1 inhibition. In addition, analysis of PBMC showed an increase in T cell activation, as measured by IFN-γ and granzymes A and B gene expression in responders following MPDL3280A treatment, consistent with the observations in responding tumors. Baseline soluble PD-L1 was not associated with response. Some indication-specific biomarkers, such as plasma VEGF, decreased in responders with RCC but not with other indications. In NSCLC, a decrease in tumor burden markers, CA-125 and CEA, was associated with response. Similarly, IL-6 and IL-8 were differentially expressed on treatment in responders vs non-responders. Additionally, responders exhibited a decrease in circulating tumor DNA (ctDNA) in plasma, suggesting that ctDNA may be used to monitor MPDL3280A clinical activity in NSCLC. In conclusion, these data provide general and indication-specific mechanistic insights into immune checkpoint inhibition, potential mechanisms of response and resistance, as well as identification of potential predictive and pharmacodynamic biomarkers of anti-PD-L1/PD-1 clinical activity across multiple tumor types.