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p53 is a transcription factor that plays a central role in guarding the genomic stability of cells through cell-cycle arrest or induction of apoptosis. However, the effects of p53 in antitumor immunity are poorly understood. To investigate the role of p53 in controlling tumor-immune cell cross-talk, we studied murine syngeneic models treated with HDM201, a potent and selective second-generation MDM2 inhibitor. In response to HDM201 treatment, the percentage of dendritic cells increased, including the CD103+ antigen cross-presenting subset. Furthermore, HDM201 increased the percentage of Tbet+Eomes+ CD8+ T cells and the CD8+/Treg ratio within the tumor. These immunophenotypic changes were eliminated with the knockout of p53 in tumor cells. Enhanced expression of CD80 on tumor cells was observed in vitro and in vivo, which coincided with T-cell–mediated tumor cell killing. Combining HDM201 with PD-1 or PD-L1 blockade increased the number of complete tumor regressions. Responding mice developed durable, antigen-specific memory T cells and rejected subsequent tumor implantation. Importantly, antitumor activity of HDM201 in combination with PD-1/PD-L1 blockade was abrogated in p53-mutated and knockout syngeneic tumor models, indicating the effect of HDM201 on the tumor is required for triggering antitumor immunity. Taken together, these results demonstrate that MDM2 inhibition triggers adaptive immunity, which is further enhanced by blockade of PD-1/PD-L1 pathway, thereby providing a rationale for combining MDM2 inhibitors and checkpoint blocking antibodies in patients with wild-type p53 tumors. Significance: This study provides a mechanistic rationale for combining checkpoint blockade immunotherapy with MDM2 inhibitors in patients with wild-type p53 tumors.

Objectives Sabatolimab is a humanized monoclonal antibody (hIgG4, S228P) directed against human T-cell immunoglobulin domain and mucin domain-3 (TIM-3). Herein, we describe the development and characterization of sabatolimab. Methods Sabatolimab was tested for binding to its target TIM-3 and blocking properties. The functional effects of sabatolimab were tested in T-cell killing and myeloid cell cytokine assays. Antibody-mediated cell phagocytosis (ADCP) by sabatolimab was also assessed. Results Sabatolimab was shown to (i) enhance T-cell killing and inflammatory cytokine production by dendritic cells (DCs); (ii) facilitate the phagocytic uptake of TIM-3-expressing target cells; and (iii) block the interaction between TIM-3 and its ligands PtdSer/galectin-9. Conclusion Taken together, our results support both direct anti-leukemic effects and immune-mediated modulation by sabatolimab, reinforcing the notion that sabatolimab represents a novel immunotherapy with immuno-myeloid activity, holding promise for the treatment of myeloid cell neoplasms.

Purpose:Sabatolimab (MBG453) and spartalizumab are mAbs that bind T-cell immunoglobulin domain and mucin domain-3 (TIM-3) and programmed death-1 (PD-1), respectively. This phase I/II study evaluated the safety and efficacy of sabatolimab, with or without spartalizumab, in patients with advanced solid tumors.Patients and Methods:Primary objectives of the phase I/Ib part were to characterize the safety and estimate recommended phase II dose (RP2D) for future studies. Dose escalation was guided by a Bayesian (hierarchical) logistic regression model. Sabatolimab was administered intravenously, 20 to 1,200 mg, every 2 or 4 weeks (Q2W or Q4W). Spartalizumab was administered intravenously, 80 to 400 mg, Q2W or Q4W.Results:Enrolled patients (n = 219) had a range of cancers, most commonly ovarian (17%) and colorectal cancer (7%); patients received sabatolimab (n = 133) or sabatolimab plus spartalizumab (n = 86). The MTD was not reached. The most common adverse event suspected to be treatment-related was fatigue (9%, sabatolimab; 15%, combination). No responses were seen with sabatolimab. Five patients receiving combination treatment had partial responses (6%; lasting 12–27 months) in colorectal cancer (n = 2), non–small cell lung cancer (NSCLC), malignant perianal melanoma, and SCLC. Of the five, two patients had elevated expression of immune markers in baseline biopsies; another three had >10% TIM-3–positive staining, including one patient with NSCLC who received prior PD-1 therapy.Conclusions:Sabatolimab plus spartalizumab was well tolerated and showed preliminary signs of antitumor activity. The RP2D for sabatolimab was selected as 800 mg Q4W (alternatively Q3W or Q2W schedules, based on modeling), with or without 400 mg spartalizumab Q4W.

Purpose: The JAK1/2 inhibitor ruxolitinib has demonstrated significant benefits for patients with myeloproliferative neoplasms (MPN). However, patients often lose response to ruxolitinib or suffer disease progression despite therapy with ruxolitinib. These observations have prompted efforts to devise treatment strategies to improve therapeutic efficacy in combination with ruxolitinib therapy. Activation of JAK–STAT signaling results in dysregulation of key downstream pathways, notably increased expression of cell-cycle mediators including CDC25A and the PIM kinases. Experimental Design: Given the involvement of cell-cycle mediators in MPNs, we sought to examine the efficacy of therapy combining ruxolitinib with a CDK4/6 inhibitor (LEE011) and a PIM kinase inhibitor (PIM447). We utilized JAK2-mutant cell lines, murine models, and primary MPN patient samples for these studies. Results: Exposure of JAK2-mutant cell lines to the triple combination of ruxolitinib, LEE011, and PIM447 resulted in expected on-target pharmacodynamic effects, as well as increased apoptosis and a decrease in the proportion of cells in S-phase, compared with ruxolitinib. As compared with ruxolitinib monotherapy, combination therapy led to reductions in spleen and liver size, reduction of bone marrow reticulin fibrosis, improved overall survival, and elimination of disease-initiating capacity of treated bone marrow, in murine models of MPN. Finally, the triple combination reduced colony formation capacity of primary MPN patient samples to a greater extent than ruxolitinib. Conclusions: The triple combination of ruxolitinib, LEE011, and PIM447 represents a promising therapeutic strategy with the potential to increase therapeutic responses in patients with MPN.

Background TIM-3 is expressed on leukemic stem cells (LSCs) and blasts in AML,1 2 and TIM-3 expression on MDS blasts correlates with disease progression.3 Functional evidence for TIM-3 in AML was established with an anti-TIM-3 antibody which inhibited engraftment and development of human AML in immuno-deficient murine hosts.1 TIM-3 promotes an autocrine stimulatory loop via the TIM-3/Galectin-9 interaction, supporting LSC self-renewal.4 In addition to its cell-autonomous role on LSCs/blasts, TIM-3 also has a critical role in immune system regulation, in adaptive (CD4+ and CD8+ T effector cells, regulatory T cells) and innate (macrophages, dendritic cells, NK cells) immune responses.5 MBG453 is a high-affinity, humanized anti-TIM-3 IgG4 antibody (Ab) (stabilized hinge, S228P), which blocks the binding of TIM-3 to phosphatidylserine (PtdSer). Recent results from a multi-center, open label phase Ib dose-escalation study (NCT03066648) in patients with high-risk MDS and no prior hypomethylating agent therapy evaluating MBG453 in combination with decitabine demonstrated encouraging preliminary efficacy with an overall response rate of 58%,6 and MBG453 combined with azacitidine also showed encouraging response rates.7 Preclinical experiments were undertaken to define the mechanism of action of the hypomethylating agent and anti-TIM-3 combination. Methods THP-1 cells (a human monocytic AML cell line) were pre-treated with decitabine and co-cultured with anti-CD3 activated healthy human donor peripheral blood mononuclear cells (PBMCs) in an Incucyte-based assay to measure cell killing. The ability of MBG453 to mediate antibody-dependent cellular phagocytosis (ADCP) was measured by determining the phagocytic uptake of an engineered TIM-3-overexpressing Raji cell line in the presence of MBG453 by phorbol 12-myristate 13-acetate (PMA)-activated THP-1 cells. Patient-derived AML xenograft studies were undertaken in immune-deficient murine hosts to evaluate the combination of decitabine and MBG453. Results MBG453 was determined to partially block the TIM-3/Galectin-9 interaction in a plate-based MSD (Meso Scale Discovery) assay, supported by a crystal structure of human TIM-3.8 Pre-treatment of THP-1 cells with decitabine enhanced sensitivity to immune-mediated killing in the presence of MBG453. MBG453 was determined to mediate modest ADCP, relative to controls. MBG453 did not enhance the anti-leukemic activity of decitabine in patient-derived xenograft studies in immuno-deficient hosts. Conclusions Taken together, these results support both direct anti-leukemic effects and immune-mediated modulation by MBG453. Further studies are ongoing to determine: (1) whether MBG453 can mediate physiologically relevant ADCP of TIM-3-expressing leukemic cells; and (2) the potential of MBG453 to impact the autocrine feedback loop of TIM-3/Galectin-9. Ethics Approval The human tissue used in these studies was under the Novartis Institutes of BioMedical Research Ethics Board IRB, Approval Number 201252867. References Kikushige Y, Shima T, Takayanagi S, et al. TIM-3 is a promising target to selectively kill acute myeloid leukemia stem cells. Cell Stem Cell 2010;7(6):708–717. Jan M, Chao MP, Cha AC, et al. Prospective separation of normal and leukemic stem cells based on differential expression of TIM3, a human acute myeloid leukemia stem cell marker. Proc Natl Acad Sci USA 2011; 108(12): 5009–5014. Asayama T, Tamura H, Ishibashi M, et al. Functional expression of Tim-3 on blasts and clinical impact of its ligand galectin-9 in myelodysplastic syndromes. Oncotarget 2017;8(51): 88904–88917. Kikushige Y, Miyamoto T, Yuda J, et al. A TIM-3/Gal-9 autocrine stimulatory loop drives self-renewal of human myeloid leukemia stem cells and leukemic progression. Cell Stem Cell 2015; 17(3):341–352. Acharya N, Sabatos-Peyton C, Anderson AC. Tim-3 finds its place in the cancer immunotherapy landscape. J Immunother Cancer 2020; 8(1):e000911. Borate U, Esteve J, Porkka K, et al. Phase Ib Study of the Anti-TIM-3 Antibody MBG453 in combination with decitabine in patients with high-risk myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). Blood 2019;134 (Supplement_1):570. Borate U, Esteve J, Porkka K, et al. Abstract S185: Anti-TIM-3 antibody MBG453 in combination with hypomethylating agents (HMAs) in patients (pts) with high-risk myelodysplastic syndrome (HR-MDS) and acute myeloid leukemia (AML): a Phase 1 study. EHA 2020. Sabatos-Peyton C. MBG453: A high affinity, ligand-blocking anti-TIM-3 monoclonal Ab. AACR 2016.

Background MBG453 and spartalizumab are humanized IgG4 mAbs that block binding of TIM-3 to PtdSer and PD-1 to PD-L1/2, respectively. In Ph I dose escalation, MBG453 + spartalizumab showed preliminary antitumor activity in advanced solid tumors. Here we report Ph II MBG453 + spartalizumab dose expansion in pts with NSCLC and melanoma (NCT02608268). Methods Pts with melanoma or NSCLC who had progressive disease (PD) on/after anti–PD-1/L1 therapy received MBG453 (800 mg, Q4W) + spartalizumab (400 mg, Q4W) until unacceptable toxicity, PD, or investigator/pt decision. On prior anti–PD-1/L1 therapy clinical benefit (CB) was defined as durable (DCB) if pts had a complete or partial response, or stable disease (SD) for ≥6 months, or non-durable (NDCB) if pts had SD for Results As of Feb 15, 2019, 33 pts received MBG453 + spartalizumab (melanoma: n = 16; NSCLC: n = 17); 5 (15.2%) pts were ongoing (melanoma: n = 3 [18.8%]; NSCLC: n = 2 [11.8%]); 28 (84.8%) pts discontinued, mainly due to PD (60.6%) and death due to underlying disease (12.1%). Anti–PD-1/L1 was the last therapy before enrollment in 21 (63.6%) pts (melanoma: n = 10 [62.5%]; NSCLC: n = 11 [64.7%]). On prior anti–PD-1/L1 therapy, 6 (37.5%) melanoma and 7 (41.2%) NSCLC pts had DCB and 10 (62.5%) melanoma and 9 (52.9%) NSCLC pts had NDCB; CB was unknown (UNK) in 1 NSCLC pt. On MBG453 + spartalizumab, 3/16 (18.8%) melanoma pts (prior anti-PD-1/L1: DCB n = 2; NDCB n = 1) and 7/17 (41.2%) NSCLC pts (prior anti-PD-1/L1: DCB n = 3; NDCB n = 3; UNK n = 1) had SD per RECIST 1.1. Baseline tumor PD-L1 appears higher in pts with SD vs PD. Data suggest a trend of inverse association between tumor reduction and CD163 tumor expression. Common treatment-related adverse events (TRAEs) were fatigue, nausea, and pruritus (n = 3 each [9.1%]); 0 melanoma and 2 (11.8%) NSCLC pts (pruritus, amylase, lipase, and increased ALT) had Grade 3/4 TRAEs. Conclusions MBG453 (800 mg, Q4W) + spartalizumab (400 mg, Q4W) was well tolerated but with limited efficacy in pts with melanoma and NSCLC who had PD on/after prior anti–PD-1/L1 therapy. Further evaluation of MBG453 in other indications/combinations is needed to assess the clinical relevance of TIM-3 inhibition. Editorial acknowledgement Jenny Winstanley, PhD, of Articulate Science Ltd. Legal entity responsible for the study Novartis Pharmaceuticals. Funding Novartis Pharmaceuticals. Disclosure G. Curigliano: Honoraria (self), Advisory Board: Novartis; Honoraria (self), Advisory Board: Roche; Speaker Bureau / Expert testimony, Expert talk: Pfizer; Speaker Bureau / Expert testimony, Expert talk: Eli Lilly; Advisory / Consultancy, Scientific consultation: Ellipsis. A. Santoro: Speaker Bureau / Expert testimony: Takeda; Advisory / Consultancy, Speaker Bureau / Expert testimony: BMS; Speaker Bureau / Expert testimony: Roche; Speaker Bureau / Expert testimony: AbbVie; Speaker Bureau / Expert testimony: Amgen; Speaker Bureau / Expert testimony: Celgene; Advisory / Consultancy, Speaker Bureau / Expert testimony: Servier; Advisory / Consultancy, Speaker Bureau / Expert testimony: Gilead; Speaker Bureau / Expert testimony: AstraZencea; Advisory / Consultancy, Speaker Bureau / Expert testimony: Pfizer; Advisory / Consultancy, Speaker Bureau / Expert testimony: Arquile; Speaker Bureau / Expert testimony: Lilly; Speaker Bureau / Expert testimony: Sandoz; Advisory / Consultancy, Speaker Bureau / Expert testimony: Eisai; Speaker Bureau / Expert testimony: Novartis; Advisory / Consultancy, Speaker Bureau / Expert testimony: Bayer; Advisory / Consultancy, Speaker Bureau / Expert testimony: MSD. D. Kim: Research grant / Funding (institution): Alpha Biopharm; Research grant / Funding (institution): AstraZeneca/MedImmune; Research grant / Funding (institution): Hanmi; Research grant / Funding (institution): Janssen; Research grant / Funding (institution): Merus; Research grant / Funding (institution): Mirati Therapeutics; Research grant / Funding (institution): MSD; Research grant / Funding (institution): Novartis; Research grant / Funding (institution): ONO Pharmaceutical; Research grant / Funding (institution): Pfizer; Research grant / Funding (institution): Roche/Genentech; Research grant / Funding (institution): Takeda; Research grant / Funding (institution): TP Therapeutics; Research grant / Funding (institution): Xcovery; Research grant / Funding (institution): Yuhan. S. Hodi: Honoraria (self), Advisory / Consultancy, Research grant / Funding (institution): Bristol Mysers Squibb; Advisory / Consultancy: Merck; Advisory / Consultancy: EMD Serono; Advisory / Consultancy, Research grant / Funding (institution): Novartis; Advisory / Consultancy: Takeda; Advisory / Consultancy: Surface; Advisory / Consultancy: Genentech/Roche; Advisory / Consultancy: Compass Therapeutics; Advisory / Consultancy: Apricity; Advisory / Consultancy: Bayer; Advisory / Consultancy: Aduro; Advisory / Consultancy: Partners Therapeutics; Advisory / Consultancy: Sanofi; Advisory / Consultancy: Pfizer; Advisory / Consultancy: Pionyr; Advisory / Consultancy: 7 Hills Pharma; Advisory / Consultancy: Verastem; Advisory / Consultancy: Torque; Advisory / Consultancy: Rheos. T. Doi: Research grant / Funding (institution): Lilly ; Research grant / Funding (institution): Taiho; Research grant / Funding (institution): Novartis; Research grant / Funding (institution): Merck Serono; Research grant / Funding (institution): MSD; Research grant / Funding (institution): Boehringer Ingelheim ; Research grant / Funding (institution): Quintiles; Research grant / Funding (institution): Pfizer; Advisory / Consultancy, Research grant / Funding (institution): Dainippon Sumitomo; Research grant / Funding (institution): Kyowa Hakko Kirin; Advisory / Consultancy, Research grant / Funding (institution): Daiichi Sankyo; Research grant / Funding (institution): BMS; Advisory / Consultancy, Research grant / Funding (institution): AbbVie; Advisory / Consultancy, Research grant / Funding (institution): Takeda; Advisory / Consultancy: Otsuka. T. Longmire: Full / Part-time employment: Novartis. H. Sun: Full / Part-time employment: Novartis. A. Xyrafas: Full / Part-time employment: Novartis. S. Gutzwiller: Shareholder / Stockholder / Stock options, Full / Part-time employment: Novartis. L. Manenti: Shareholder / Stockholder / Stock options, Full / Part-time employment: Novartis. All other authors have declared no conflicts of interest.

Co-senior authors Andrew Brunner and Andrew H. Wei contributed equally to this work Background: MBG453 is a high-affinity humanized anti-TIM-3 (T-cell immunoglobulin domain and mucin domain-3) IgG4 antibody in development for the treatment of MDS, AML, and other malignancies. TIM-3 is an immune checkpoint with a complex regulatory role in both adaptive and innate immune responses and is also preferentially expressed on leukemic stem and progenitor cells, making it a potential target in MDS and AML. MBG453 has been shown to enhance immune cell-mediated killing of AML cells in vitro. Hypomethylating agents (HMAs) have been shown to increase immune checkpoint expression in MDS and AML, providing rationale to study the combination of HMAs with MBG453. Methods: Patients with Revised International Prognostic Scoring System (IPSS-R) high or very high-risk (HR) MDS and newly diagnosed, or relapsed/refractory (R/R), AML following ≥ 1 prior therapy who were not candidates for standard chemotherapy and who were HMA naive were enrolled in this multi-center, open label phase Ib dose-escalation study (NCT03066648). Escalating doses of MBG453 were administered i.v. every 2 weeks (Q2W; days 8, 22) or every four weeks (Q4W; day 8) in combination with decitabine (20 mg/m2; i.v. days 1-5). The primary objectives were to characterize the safety and tolerability of MBG453 in combination with decitabine and to identify recommended doses for future studies. Secondary objectives included assessing preliminary efficacy and pharmacokinetics of the combination. Dose escalation followed a Bayesian logistic regression model based on dose-limiting toxicities (DLTs). Adverse events (AEs) were graded using NCI-CTCAE v4.03. The International Working Group criteria for MDS (Cheson et al, 2006) or AML (Cheson et al, 2003) were used to assess efficacy. Results: As of March 25, 2019, 17 HR-MDS, 4 chronic myelomonocytic leukemia (CMML), and 38 AML patients have received decitabine and MBG453 at 240 mg Q2W (n=22), 400 mg Q2W (n=21), or 800 mg Q4W (n=16). MTD has not been reached. Median age was 70 years (range 23-87 years). 24 patients are ongoing (duration of exposure 1.1 to 18.6 months) with 35 patients discontinued (disease progression [n=19, 32%], AE [n=1, 2%], patient/physician decision [n=13, 22%], death [n=2, 3%]). There was one DLT consisting of a grade 3 ALT elevation that was corticosteroid responsive. The most common treatment emergent grade 3/4 AEs were febrile neutropenia (39%), neutropenia (34%), thrombocytopenia (31%), and anemia (29%). A total of 8 patients (14%) developed ≥ grade 2 suspected immune related AEs (irAEs) considered to be MBG453 related; 4 of whom (7%) presented with grade 3/4 events: ALT elevation (n=2), arthritis (n=1), and GGT increase (n=1). No study treatment-related deaths were observed. 16 HR-MDS and 31 AML patients have had post-baseline disease response assessments. Median duration of decitabine and MBG453 is 3.9 months (range 0.7-18.6 months). Evidence of activity with MBG453 in combination with decitabine has been seen at doses ranging from 240 mg Q2W to 800 mg Q4W. 8 of 16 (50%) HR-MDS patients achieved mCR or CR. None of the responding HR-MDS patients has had disease recurrence with exposure durations currently ranging from 3.4 to 18.6 months; two patients in mCR underwent allogeneic stem cell transplant. 4 of 14 (29%) newly diagnosed AML patients have achieved a response of PR or better (2 PR, 2 CR), with 3 additional patients exhibiting ≥ 50% bone marrow blast reduction, and 10 of 14 (71%) continuing on study. 5 of 17 (29%) R/R AML patients have achieved a response of CRi, with 5 additional patients exhibiting ≥ 50% bone marrow blast reduction. Exposure durations for all AML responders currently range from 2.1 to 17.9 months. Median onset of response among all patients was 2.0 months. TIM-3 expression was detected on leukemic cells, with modulation of TIM-3 expression following treatment with decitabine. Conclusions: In this ongoing study in patients with HR-MDS and AML, the combination of MBG453 and decitabine was safe and well tolerated, and exhibited evidence of anti-leukemic activity with encouraging preliminary response rates occurring at a median of 2 cycles, with durability in both HR-MDS and AML. These findings validate TIM-3 as a promising therapeutic target in MDS and AML and support further clinical development of MBG453 in combination with HMAs in patients with MDS and AML. Disclosures Borate: AbbVie: Consultancy; Daiichi Sankyo: Consultancy; Pfizer: Consultancy; Novartis: Consultancy; Takeda: Consultancy. Esteve:Novartis: Consultancy, Research Funding, Speakers Bureau; Amgen: Consultancy; Daiichi Sankyo: Consultancy; Celgene: Consultancy, Speakers Bureau; Jazz Pharmaceuticals: Consultancy; Roche: Consultancy; Astellas: Consultancy, Speakers Bureau; Pfizer: Consultancy. Porkka:Daiichi Sankyo: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Novartis: Consultancy, Research Funding. Knapper:Novartis: Consultancy, Honoraria, Research Funding, Speakers Bureau; Jazz: Consultancy, Speakers Bureau; Tolero: Consultancy; Daiichi Sankyo: Honoraria; Pfizer: Consultancy. Vey:Janssen: Honoraria; Novartis: Consultancy, Honoraria. Scholl:Novartis: Other: Project funding; Pfizer: Other: Advisory boards; Gilead: Other: Project funding; AbbVie: Other: Advisory boards; Daiichi Sankyo: Other: Advisory boards. Garcia-Manero:Amphivena: Consultancy, Research Funding; Helsinn: Research Funding; Novartis: Research Funding; AbbVie: Research Funding; Celgene: Consultancy, Research Funding; Astex: Consultancy, Research Funding; Onconova: Research Funding; H3 Biomedicine: Research Funding; Merck: Research Funding. Wermke:Novartis: Honoraria, Research Funding. Janssen:Amsterdam University Medical Center, location VUmc, Amsterdam, The Netherlands: Employment; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Other: Founder of the HematologyApp which is supported by BMS, among others, Research Funding; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Founder of the HematologyApp which is supported by Pfizer, among others; Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Founder of the HematologyApp which is supported by Incyte, among others; AbbVie: Membership on an entity's Board of Directors or advisory committees; Janssen: Other: Founder of the HematologyApp which is supported by Janssen, among others; MSD: Other: Founder of the HematologyApp which is supported by MSD, among others; Daiichi-Sankyo: Other: Founder of the HematologyApp which is supported by Daiichi-Sankyo, among others; Roche: Other: Founder of the HematologyApp which is supported by Roche, among others; Takeda: Other: Founder of the HematologyApp which is supported by Takeda, among others. Traer:AbbVie: Consultancy; Notable Labs: Equity Ownership; Agios: Consultancy; Astellas: Consultancy; Daiichi Sankyo: Consultancy. Chua:Alfred Hospital, Melbourne, Australia: Employment. Narayan:Takeda: Other: Employment (spouse); Merck: Other: Equity ownership (spouse); Genentech: Other: Equity ownership (spouse). Tovar:Hospital Clinic Barcelona: Employment. Kontro:Amgen: Consultancy; Astellas: Consultancy; AbbVie: Research Funding, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees. Ottmann:Roche: Honoraria; Pfizer: Honoraria; Fusion Pharma: Honoraria; Takeda: Honoraria; Novartis: Honoraria; Celgene: Honoraria, Research Funding; Incyte: Honoraria, Research Funding; Amgen: Honoraria, Research Funding. Sun:Novartis Institutes for BioMedical Research: Employment; Novartis: Other: Novartis stock owner (stock share as long-term employee incentive). Longmire:Novartis Pharmaceuticals: Employment, Equity Ownership, Patents & Royalties. Szpakowski:Novartis Institutes for Biomedical Research: Employment, Other: Novartis Stock. Liao:Novartis: Employment. Patel:Novartis Pharmaceuticals: Employment. Rinne:Novartis: Employment; N-Of-One, Inc: Consultancy. Brunner:Astra Zeneca: Research Funding; Forty Seven Inc: Membership on an entity's Board of Directors or advisory committees; Novartis: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Jazz Pharma: Membership on an entity's Board of Directors or advisory committees. Wei:Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees; Astra Zeneca: Honoraria, Research Funding; Janssen: Honoraria; Servier: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Macrogenics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties: AHW is a former employee of the Walter and Eliza Hall Institute and receives a fraction of its royalty stream related to venetoclax, Research Funding, Speakers Bureau; Astellas: Honoraria, Membership on an entity's Board of Directors or advisory committees. OffLabel Disclosure: MBG453 is an investigational anti-TIM-3 antibody that is being evaluated in hematological malignancies and solid tumors

Background: MBG453 and spartalizumab, humanized IgG4 mAbs, block binding of TIM-3 to PtdSer and PD-1 to PD-L1/2, respectively. Preclinical studies show synergistic anti-tumor activity of TIM-3 and PD-1 co-blockade. Here we report the dose escalation results from a Ph I-Ib/II study of MBG453 ± spartalizumab in metastatic solid tumors (NCT02608268). Methods: Metastatic cancer pts received intravenous MBG453 alone at 80-1200 mg Q2W or Q4W, or combination therapy (Q2W/Q4W) with MBG453 (20-800/80-1200 mg) + spartalizumab (80-240 mg/80-400 mg). The recommended Ph II dose (RP2D) was determined using an adaptive Bayesian logistic regression model guided by escalation with overdose control together with Ph I-Ib endpoints (dose-limiting toxicity [DLT] at 8 weeks). Results: As of July 26, 2018, 87 pts received MBG453 alone (14% were anti-PD-1/PD-L1 pre-treated; common tumors [≥9%]: pancreatic cancer [11%], sarcoma [10%], and colorectal cancer [CRC; 9%]) and 86 pts received MBG453 + spartalizumab (27% were anti-PD-1/PD-L1 pre-treated; common tumors [≥6%]: melanoma [8%], NSCLC [7%], CRC [7%], and ovarian cancer [6%]). One DLT (myasthenia gravis grade [G] 4) was reported in a pt with thymoma treated with MBG453 (240 mg Q4W) + spartalizumab (80 mg Q4W). Treatment-related adverse events (AEs) were reported in 40% and 59% of pts treated with MBG453 and MBG453 + spartalizumab, and G3/4 AEs in 0% and 11% of pts; the most common AE (≥10%) was fatigue in 10% and 15% of pts, respectively. MBG453 exposure generally increased in a dose-proportional manner. Maximum tolerated doses were not identified with the tested dose/schedule. MBG453 800 mg Q4W (n=9 pts treated) and MBG453 800 mg + spartalizumab 400 mg Q4W (n=6 pts treated) were declared as RP2Ds. Stable disease (SD) was seen in 25/87 (29%) pts treated with MBG453 alone (common tumors [≥2 pts]: sarcoma [n=5], and breast cancer, CRC, ovarian cancer, cholangiocarcinoma, and NSCLC [n=2 pts each]); 4 of 25 pts with SD were anti-PD-1/PD-L1 pre-treated. Of 86 MBG453 + spartalizumab pts, partial responses were seen in 4 pts (5%); 1 anti-PD-1/PD-L1 pre-treated pt (out of 6 with NSCLC; DOR: 392 d), 3 anti-PD-1/PD-L1 naïve pts (CRC [n=2 out of 6, DOR: 223 d, 109 d]; SCLC [n=1 out of 3; DOR: 112 d]). SD was seen in 34/86 (40%) MBG453 + spartalizumab pts (common tumors [≥3 pts]: melanoma [n=5; 2 cutaneous, 2 uveal, and 1 non-cutaneous], ovarian cancer [n=3], and urothelial carcinoma [n=3]); 10 of 34 pts with SD were anti-PD-1/PD-L1 pre-treated. RNAseq analysis of screening and on-treatment biopsies revealed a pharmacodynamic trend of increased IFN-γ-associated gene signatures following MBG453 + spartalizumab treatment. Conclusions: MBG453 + spartalizumab was well tolerated with preliminary signs of anti-tumor activity. MBG453 800 mg Q4W and MBG453 800 mg + spartalizumab 400 mg Q4W were selected as the RP2Ds; dose expansion is ongoing in pts with melanoma or NSCLC resistant to anti-PD-1/PD-L1. Citation Format: Giuseppe Curigliano, Hans Gelderblom, Nicolas Mach, Toshihiko Doi, Wai Meng David Tai, Patrick Forde, John Sarantopoulos, Philippe L. Bedard, Chia-Chi Lin, Stephen Hodi, Sofie Wilgenhof, Armando Santoro, Catherine Sabatos-Peyton, Tyler Longmire, Kitty Wan, Panagiotis Nikolopoulos, Luigi Manenti, Aung Naing. Phase (Ph) I/II study of MBG453± spartalizumab (PDR001) in patients (pts) with advanced malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT183.

Tumor immunotherapy is a unique therapeutic modality in our fight against human cancers. The recent success of immune-checkpoint therapies highlights the value and potential of this approach. Previous studies have demonstrated positive immune-modulatory activities of the IAP inhibitor, NVP-LCL161. In this study, we sought to further explore the immune-modulatory activities of NVP-LCL161 in connection with immune-checkpoint molecules. In PBMC stimulation assays, NVP-LCL161 potently induced IFN and enhanced proliferation, while down-modulating IL-10 production. Additionally, the role of NVP-LCL161 on immune-checkpoint modulation was revealed in CyTOF analysis of in vitro stimulated PBMCs. NVP-LCL161 treatment led to increases in TIM-3 expression on multiple T cell subsets, and on cells of the myeloid lineage. These observations illustrate potential modulation of specific immune-checkpoint molecule by NVP-LCL161, thus suggesting possible synergy between TIM-3 immunecheckpoint blockade and NVP-LCL161. NVP-LCL161 was further combined in vivo with anti-PD1 antibody in the murine syngeneic tumor model, MC38. At multiple dosing schedules, synergy was observed with this combination, which appeared to be independent of single agent efficacy. Expression profiling of MC38 tumor tissues by a customized Nanostring panel revealed elevation of gene signatures in T cells, dendritic cells, cytokines and chemokines, amongst others. In summary, the preclinical data support the hypothesis that NVP-LCL161 is an active immune modulator. Its combination activity with immune_checkpoint inhibitors would warrant further exploration in both preclinical and clinical setting. Citation Format: Maria Pinzon-Ortiz, William Hastings, Tyler Longmire, Pamela Shaw, Xianhui Rong, Masato Murakami, Benjamin H. Lee, Glenn Dranoff, Kenzie MacIsaac, Z. Alexander Cao. The immune modulatory roles of IAP inhibitor, LCL161, and its connection to immune-checkpoint molecules. [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 2343.

The JAK-STAT pathway is an important signaling pathway downstream of multiple cytokine and growth factor receptors. The genetic aberration of JAK2V617F and the associated activation of STAT in myeloproliferative neoplasia (MPN) is one example of the involvement of this pathway in human cancer. We have previously shown the combination benefits of combining ruxolitinib (Jak1,2 inhibitor), with LGH447 (PIM inhibitor) and LEE011 (CDK4/6 inhibitor) in a Ba/F3-JAK2V617F-driven MPN model. Here, we set to explore the molecular and cellular mechanisms underlying this combination benefit in the JAK2V617F UKE-1 model of MPN. The triple combination of ruxolitinib, LGH447 and LEE011 resulted in sustained tumor regression in the UKE-1 model. Ruxolitinib, LGH447 and LEE011 inhibited pSTAT5, pBAD and pRb respectively. The monotherapies and the combination of ruxolitinib + LGH447 did not affect G1-S cycle. In contrast, the combination of ruxolitinib+LEE011, LGH447+LEE011 and the triple combination resulted in significant inhibition of G1-S progression. Consequently, after 72 hours of treatment, the percentage of cells in S phase decreased from 67% under DMSO to 15.8% under ruxolitinib+LEE011, and to 1.6% under the triple combination. Furthermore, monotherapies of LGH447 or LEE011 did not affect cell viability. Ruxolitinib monotherapy and ruxolitinib+LGH447 combination reduced viable cell% by 47% and 86%, respectively. The triple combination reduced it by 91%. Our data suggest that the triple combination efficacy is the result of both cell killing and cell cycle blockade. The inhibition of JAK-PIM pathway significantly reduced cell viability. And the inclusion of CDK4/6 inhibition by LEE011 lead to more potent cell killing and cell growth arrest. Taken together, the triple combination achieves sustained tumor regression in preclinical models of MPN. Citation Format: Maria Pinzon-Ortiz, Tyler Longmire, Xianhui Rong, Giordano Caponigro, Gary Vanasse, Benjamin H. Lee, Z. Alexander Cao. Molecular and cellular mechanisms underlying the therapeutic efficacy of the combination of JAK inhibitor, ruxolitinib, PIM inhibitor, LGH447, and CDK4/6 inhibitor, LEE011, in a preclinical model of myeloproliferative neoplasia. [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 2522. doi:10.1158/1538-7445.AM2015-2522