Antitumor Activity Of Combination Research Articles

Induction of P-glycoprotein expression by dandelion in tumor and heart tissues: Impact on the anti-tumor activity and cardiotoxicity of doxorubicin

BackgroundPreviously, we have investigated the anti-tumor activity and mechanism through which dandelion acts against triple-negative breast cancer (TNBC). However, traditional Chinese medicine is mostly accepted as an adjunct therapy during chemotherapy in clinical practice. So far, little is known about the effects of dandelion in conjunction with chemotherapeutic drugs. PurposeTo investigate the effects of dandelion on the anti-tumor activity and cardiotoxicity of doxorubicin (DOX), and to further explore the molecular mechanisms through which these effects occur. Study designAt the beginning of this study, dandelion was observed to alleviate DOX-induced cardiotoxicity and reduce the anti-tumor activity of DOX. Subsequently, we investigated whether the resistance to DOX mediated by P-glycoprotein was involved in the above effects. MethodsThe cardioprotective effect of dandelion was investigated on DOX-treated mice by histological analysis, myocardial enzyme assays, and an untargeted metabolomics study based on LC-Q-TOF/MS. TNBC cell lines and 4T1 tumor-bearing mice were employed to investigate the combined anti-tumor activity. Laser scanning confocal microscope and a flow cytometry analysis were employed to measure the intracellular accumulation of DOX. A specific, sensitive, and rapid LC–MS/MS method was developed to detect the efflux of DOX from cells. Expression of P-glycoprotein in mouse tumor and heart tissues was detected via Western blotting analysis. ResultsDandelion was found to significantly alleviate DOX-induced cardiotoxicity, as was evidenced by improved cardiomyocyte morphology, decreased LDH and CK-MB release, and adjusted metabolic biomarker levels. However, in vitro and in vivo studies showed that dandelion could reduce the anti-tumor activity of DOX. This counteraction was achieved by activating of the drug efflux transporter P-glycoprotein, thereby promoting the efflux of DOX from cells and reducing the intracellular accumulation of DOX. Moreover, the activation of P-glycoprotein by dandelion in mouse heart tissue was also observed, thus suggesting that the decrease of cardiac DOX accumulation plays an important role in the cardioprotective effect of dandelion. ConclusionDandelion can activate the P-glycoprotein in heart and tumor tissues, which ameliorates DOX-induced cardiotoxicity but attenuates DOX cytotoxicity toward TNBC. Our findings have important implications for the correct clinical use of dandelion.

A phase 1/2 study of DCC-3116 as a single agent and in combination with trametinib in patients with advanced or metastatic solid tumors with RAS or RAF mutations.

TPS3178 Background: Autophagy, a catabolic process to resupply nutrients and recycle damaged organelles, is activated by cancer cells to survive hypoxia, limited nutrients, or chemotherapy. The RAS family of oncoproteins are the most commonly mutated oncoproteins in human cancer and require autophagy for tumor growth and survival. RAS activates signaling through the mitogen-activated protein kinase (MAPK) pathway that is responsible for regulating cell survival. ULK1/2 are kinases that receive and process input from nutrient and stress sensors to initiate autophagy. Inhibition of the MAPK pathway releases tonic inhibition of ULK1/2 and triggers autophagy as a survival mechanism, suggesting that ULK1/2 may provide a promising therapeutic target. DCC-3116 is a potent and selective ULK inhibitor that showed preclinical antitumor activity in combination with the MAPK kinase inhibitor trametinib (Smith et al. 2019 AACR-NCI-EORTC Poster). Here, we describe the Phase 1 study of DCC-3116 monotherapy and combination therapy with trametinib in patients with RAS or RAF mutant advanced or metastatic solid tumors. Methods: This is a Phase 1/2, multicenter, open-label, first-in-human study evaluating safety, tolerability, clinical activity, pharmacokinetics, and pharmacodynamics of DCC-3116 as a single agent and in combination with trametinib (NCT04892017). The study consists of single agent and combination dose escalation cohorts and expansion of combinations with demonstrated safety. Single-agent oral DCC-3116 will be administered twice daily (BID) in escalating cohorts in 28-day cycles until the recommended Phase 2 dose (RP2D) is determined. Subsequently, the single-agent RP2D or one level below the maximum tolerated dose (MTD) will be administered in combination with trametinib. Participants in the dose escalation phase must be ≥18 years with a histologically confirmed diagnosis of advanced or metastatic solid tumor with a documented RAS or RAF mutation, have progressed despite standard therapies, and have received ≥1 prior anticancer therapy. In the dose expansion phase, DCC-3116 will be given BID with trametinib in 28-day cycles to participants with pancreatic ductal adenocarcinoma, non-small cell lung cancer, colorectal cancer, or melanoma (Cohorts 1–4, respectively). Primary outcomes are incidence of adverse events, identification of MTD, and objective response rate per RECIST v1.1. Secondary outcomes include duration of response, clinical benefit rate, time to response, progression-free survival, and pharmacokinetic/pharmacodynamic attributes. Participants in dose expansion cohorts must be ≥18 years and meet cohort-specific criteria including histologically confirmed diagnoses, documented mutation status, and number of prior lines of systemic therapy. This study is recruiting and plans to enroll up to 130 participants. Clinical trial information: NCT04892017.

First-in-human study of pelcitoclax (APG-1252) in combination with paclitaxel in patients (pts) with relapsed/refractory small-cell lung cancer (R/R SCLC).

e20612 Background: Targeting BCL-2/BCL-xL proteins is considered an important approach for anticancer drug development. Investigational pelcitoclax (APG-1252) as a single agent is a novel BCL-2/BCL-xL dual inhibitor, which has demonstrated synergistic antitumor activity in combination with chemotherapy preclinically through targeting both BCL-xL and MCL-1 pathways. The phase I study of pelcitoclax suggested promising antitumor activity and a favorable safety profile. Methods: The primary aim of this study was to determine the safety and preliminary efficacy of pelcitoclax combined with paclitaxel in patients with R/R SCLC. Patients received pelcitoclax 160 mg or 240 mg IV infusion on Days 1, 8, and 15 plus paclitaxel 80 mg/m2 on Days 1 and 8 of a 21-day cycle. The primary endpoint of phase Ib was to characterize the safety and tolerability of the combination. The primary endpoint of phase 2 was the objective response rate (ORR) of pelcitoclax at the RP2D plus paclitaxel using RECIST v1.1. Results: On December 20, 2021, 28 pts (median age, 63 [range, 37-77] years) were enrolled. The median (range) duration of treatment was 84 (7-259) days. The RP2D of pelcitoclax was determined to be 240 mg. A total of 26 pts experienced any grade treatment-related adverse events (TRAEs), including anemia (32.1%); ALT or AST elevation (28.6% each); neutropenia (25%); fatigue, leukopenia, or thrombocytopenia (21.4% each); peripheral neuropathy, nausea, or alopecia (17.9% each); peripheral sensory neuropathy or decreased appetite (14.3% each); and lymphopenia, hyponatremia, or dizziness (10.7% each). A total of 15 pts had at least one ≥ grade 3-4 TRAE, and 11 (39.3%) had serious AEs. No dose-limiting toxicity was reported. A total of 5 of 20 evaluable pts (4 pts in the 240 mg cohort and 1 in the 160 mg cohort) reported PR (ORR 25%), with a median response duration of 83 days. The pharmacokinetics profile showed that pelcitoclax systemic exposure increased between 160 and 240 mg, with an average terminal half-life of 3.7 to 7.4 hours and without any drug-drug interaction. Conclusions: Pelcitoclax was well tolerated at doses of up to 240 mg/week. Treatment with pelcitoclax 240 mg and paclitaxel 80 mg/m2 demonstrated modest antitumor activity in pts with R/R SCLC. Further clinical exploration, preferably in selected patient populations with relevant biomarkers, is warranted to fully elucidate the clinical activity of pelcitoclax. Clinical trial information: NCT04210037.

Phase Ib/II Trial of Ribociclib in Combination with Binimetinib in Patients with NRAS-mutant Melanoma.

Enhanced MAPK pathway signaling and cell-cycle checkpoint dysregulation are frequent in NRAS-mutant melanoma and, as such, the regimen of the MEK inhibitor binimetinib and the selective CDK4/6 inhibitor ribociclib is a rational combination. This is a phase Ib/II, open-label study of ribociclib + binimetinib in patients with NRAS-mutant melanoma (NCT01781572). Primary objectives were to estimate the MTD/recommended phase II dose (RP2D) of the combination (phase Ib) and to characterize combination antitumor activity at the RP2D (phase II). Tumor genomic characterization and pharmacokinetics/pharmacodynamics were also evaluated. Ten patients (16.4%) experienced dose-limiting toxicities in cycle 1 of phase Ib. Overall response rate in the phase II cohort (n = 41) for the selected RP2D (binimetinib 45 mg twice daily + ribociclib 200 mg once daily, 21 days on/7 days off) was 19.5% [8/41; 95% confidence interval (CI), 8.8-34.9]. The response rate was 32.5% (13/40; 95% CI, 20.1-48.0) in patients with NRAS mutation with concurrent alterations of CDKN2A, CDK4, or CCND1. Median progression-free survival was 3.7 months (95% CI, 3.5-5.6) and median overall survival was 11.3 months (95% CI, 9.3-14.2) for all patients. Common treatment-related toxicities included creatine phosphokinase elevation, rash, edema, anemia, nausea, diarrhea, and fatigue. Pharmacokinetics and safety were consistent with single-agent data, supporting a lack of drug-drug interaction. Ribociclib + binimetinib can be safely administered and is clinically active in patients with NRAS-mutant melanoma. Co-mutations of cell-cycle genes may define a population with greater likelihood of treatment benefit. See related commentary by Moschos, p. 2977.

Abstract OT1-14-01: Zanidatamab in combination with ALX148 in advanced human epidermal growth factor receptor 2 (HER2)-expressing cancers, including breast cancer: A phase 1b/2, multicenter, open-label, dose-finding and cohort-expansion study (ZWI-ZW25-204)

Abstract Background: HER2-targeted therapies have led to marked improvements in survival for patients with HER2-positive breast cancer. Despite the gains obtained with current HER2-targeted therapies, an unmet medical need remains for patients with HER2-expressing (high or low expression) advanced breast cancer that has progressed after prior treatments. Zanidatamab is a novel HER2-targeted bispecific antibody that has multiple mechanisms of action, including immune clearance of HER2-expressing tumor cells through antibody-dependent cellular phagocytosis. Zanidatamab has been shown to be well-tolerated and has demonstrated antitumor activity, both as monotherapy and in combination with chemotherapy, across HER2-expressing solid tumors in a Phase 1 study. ALX148 is a high affinity CD47-blocking fusion protein with an inactive human immunoglobulin Fc region designed to enhance the activity of anticancer therapies, including antibodies, with minimal added hematologic toxicity. Treatment with zanidatamab in combination with ALX148 has the potential to augment the immune clearance of HER2-expressing cancer cells by blocking the CD47-SIRPa interaction that inhibits phagocytosis of the same cancer cells. In a Phase 1 study, ALX148 demonstrated antitumor activity when combined with trastuzumab in patients whose disease had progressed on prior HER2-targeted therapies. Here, we describe a Phase 1b/2 study to investigate the safety and antitumor activity of a chemotherapy-free combination of zanidatamab plus ALX148 in advanced HER2-expressing cancers, including breast cancer. Methods: ZWI-ZW25-204 is a Phase 1b/2, 2-part, open-label, multicenter study to evaluate the safety and antitumor activity of zanidatamab administered in combination with ALX148 in patients with locally advanced/inoperable and/or metastatic HER2-expressing cancer. Part 1 of this study will evaluate safety and tolerability and will establish the recommended doses (RDs) of zanidatamab plus ALX148. It will include patients with either HER2-positive (defined per ASCO/CAP guidelines) or HER2-low (defined as immunohistochemistry [IHC] 1+ or IHC 2+/in situ hybridization (ISH) negative) breast cancer. Part 2 will evaluate the antitumor activity of zanidatamab plus ALX148 (at their combination therapy RDs) in 3 expansion cohorts: HER2-positive breast cancer (Cohort 1), HER2-low breast cancer (Cohort 2) and other HER2-overexpressing advanced malignancies (Cohort 3). Other key eligibility criteria include: prior use of approved agents known to confer clinical benefit, disease progression on or after the most recent systemic therapy, measurable disease per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1). Patients will receive zanidatamab and ALX148, each administered intravenously once every 2 weeks in a 28-day treatment cycle. Response assessments will be performed every 8 weeks. Primary endpoints include safety and tolerability assessments (Part 1) and confirmed objective response rate per RECIST 1.1 (Part 2). Secondary endpoints in Part 2 include disease control rate, clinical benefit rate, duration of response, progression-free survival, overall survival, safety, pharmacokinetics, and immunogenicity assessments. The study is currently open for enrollment in the United States and may enroll up to 93 patients (NCT: 05027139). Citation Format: Sara A. Hurvitz, Jorge Chaves, Adam Brufsky, Alberto J. Montero, Bruno Fang, Kay Yeung, Manish R. Patel, Ritesh Parajuli, Adam Omidpanah, Elaina Gartner, Abraham Fong, Sophia Randolph, Funda Meric-Bernstam. Zanidatamab in combination with ALX148 in advanced human epidermal growth factor receptor 2 (HER2)-expressing cancers, including breast cancer: A phase 1b/2, multicenter, open-label, dose-finding and cohort-expansion study (ZWI-ZW25-204) [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr OT1-14-01.

Nivolumab (NIVO) + 5-fluorouracil/leucovorin/oxaliplatin (mFOLFOX6)/bevacizumab (BEV) versus mFOLFOX6/BEV for first-line (1L) treatment of metastatic colorectal cancer (mCRC): Phase 2 results from CheckMate 9X8.

8 Background: Standard 1L therapies for mCRC include a fluoropyrimidine with oxaliplatin and/or irinotecan, and a biologic agent. NIVO may enhance antitumor activity in combination with 1L standard therapies within a subset of patients (pts) with mCRC. CheckMate 9X8 evaluated NIVO + mFOLFOX6/BEV vs mFOLFOX6/BEV in 1L mCRC (NCT03414983). Methods: Adults with previously untreated, unresectable, mCRC were randomized 2:1 to NIVO 240 mg + mFOLFOX6/BEV Q2W (NIVO + standard-of-care [SOC]) or mFOLFOX6/BEV Q2W (SOC). Primary endpoint was progression-free survival (PFS) assessed by blinded independent central review (BICR) per RECIST v1.1. Key secondary endpoints included objective response rate (ORR), disease control rate (DCR), time to response (TTR), duration of response (DOR), overall survival (OS), and safety. Results: 195 pts were randomized to NIVO + SOC (n = 127) or SOC (n = 68). Median (range) follow-up was 23.7 (0–33.2) months (mo; NIVO + SOC) vs 23.2 (0–32.3) mo (SOC). Median (range) duration of therapy was 9.9 (0.1–31.8+) mo (NIVO + SOC) and 7.7 (0.1–26.7+) mo (SOC). The HR (95% CI) for PFS was 0.81 (0.53–1.23; P = 0.30), which did not meet the prespecified threshold for statistical significance (median PFS, 11.9 mo in both arms; Table). PFS rates after 12 mo were higher with NIVO + SOC vs SOC (Table). ORR was 60% (NIVO + SOC) and 46% (SOC; odds ratio 1.72 [95% CI 0.96–3.10]) and median (95% CI) DOR was 12.9 (9.0–13.1) mo (NIVO + SOC) and 9.3 (7.5–11.3) mo (SOC; Table). Rates of grade 3−4 treatment-related adverse events (TRAEs) were higher with NIVO + SOC; however, no new safety signals were identified (Table). Biomarker analyses, including tumor mutational burden and baseline CD8 levels, will be presented. Conclusions: The primary endpoint of PFS was not met; however, NIVO + SOC showed higher PFS rates after 12 mo, a higher response rate, and more durable responses compared with SOC, along with acceptable safety, in 1L mCRC. Clinical trial information: NCT03414983. [Table: see text]

Fc-based Duokines: dual-acting costimulatory molecules comprising TNFSF ligands in the single-chain format fused to a heterodimerizing Fc (scDk-Fc)

ABSTRACT Targeting costimulatory receptors of the tumor necrosis factor superfamily (TNFSF) to activate T-cells and promote anti-tumor T-cell function have emerged as a promising strategy in cancer immunotherapy. Previous studies have shown that combining two different members of the TNFSF resulted in dual-acting costimulatory molecules with the ability to activate two different receptors either on the same cell or on different cell types. To achieve prolonged plasma half-life and extended drug disposition, we have developed novel dual-acting molecules by fusing single-chain ligands of the TNFSF to heterodimerizing Fc chains (scDuokine-Fc, scDk-Fc). Incorporating costimulatory ligands of the TNF superfamily into a scDk-Fc molecule resulted in enhanced T-cell proliferation translating in an increased anti-tumor activity in combination with a primary T-cell-activating bispecific antibody. Our data show that the scDk-Fc molecules are potent immune-stimulatory molecules that are able to enhance T-cell mediated anti-tumor responses.

AMEERA-5: a randomized, double-blind phase 3 study of amcenestrant plus palbociclib versus letrozole plus palbociclib for previously untreated ER+/HER2- advanced breast cancer.

Background:For estrogen receptor–positive (ER+)/human epidermal growth factor receptor 2–negative (HER2–) advanced breast cancer (ABC), the current standard first-line treatment includes an aromatase inhibitor in combination with a cyclin-dependent kinase 4/6 inhibitor. When resistance occurs, often related to the occurrence of ESR1 mutations, selective estrogen receptor modulators or degraders (SERDs) may be used, alone or in combination regimens. Amcenestrant (SAR439859), an optimized oral SERD, has shown clinical antitumor activity in combination with palbociclib in patients with ER+/HER2– ABC and, as monotherapy, in patients with and without ESR1 mutations. Here, we describe the study design of AMEERA-5, an ongoing, prospective, phase 3, randomized, double-blind, multinational study comparing the efficacy and safety of amcenestrant plus palbociclib versus letrozole plus palbociclib in patients with advanced (locoregional recurrent or metastatic) ER+/HER2– breast cancer.Methods:Patients are pre-/postmenopausal women and men with no prior systemic therapy for ABC. The planned enrollment is 1066 patients. Patients are randomized 1:1 to either amcenestrant 200 mg plus palbociclib 125 mg or letrozole 2.5 mg plus palbociclib 125 mg. Amcenestrant, letrozole, and their matching placebos are taken once daily continuously; palbociclib is taken once daily for 21 days, followed by 7 days off-treatment for a 28-day cycle. Treatment continues until disease progression, unacceptable toxicity, or decision to stop treatment. Pre-/perimenopausal women and men receive goserelin subcutaneously. Randomization is stratified by de novo metastatic disease, menopausal status, and visceral metastases. The primary endpoint is progression-free survival. The key secondary endpoint is overall survival; others are safety, pharmacokinetics, and quality of life.Conclusions:AMEERA-5 is evaluating the efficacy and safety of amcenestrant in combination with palbociclib as first-line therapy in pre-/postmenopausal women and men with ER+/HER2– ABC.ClinicalTrials Identifier:NCT04478266.

Antitumor immune effects of preoperative sitravatinib and nivolumab in oral cavity cancer: SNOW window-of-opportunity study

BackgroundSitravatinib, a tyrosine kinase inhibitor that targets TYRO3, AXL, MERTK and the VEGF receptor family, is predicted to increase the M1 to M2-polarized tumor-associated macrophages ratio in the tumor microenvironment...

264P AMEERA-1: Subgroup analyses of phase I/II study of amcenestrant (SAR439859), an oral selective estrogen receptor (ER) degrader (SERD), with palbociclib in postmenopausal women with ER+/ human epidermal growth factor receptor 2-negative (HER2–) advanced breast cancer (aBC)

Amcenestrant is an optimized, oral SERD that has shown favorable safety and encouraging antitumor activity in combination with palbociclib (palbo) in ER+/HER2– aBC. Here, we report updated data, including antitumor activity by subgroups.

Intratumoral injection of TLR9 agonist promotes an immunopermissive microenvironment transition and causes cooperative antitumor activity in combination with anti-PD1 in pancreatic cancer

BackgroundComplex tumor and immune microenvironment render pancreatic ductal adenocarcinoma (PDAC) resistant to immune checkpoint inhibitors (ICIs). Therefore, a strategy to convert the immune hostile into an immunopermissive tumor is required....

Green tea catechins in combination with irinotecan attenuates tumorigenesis and treatment-associated toxicity in an inflammation-associated colon cancer mice model

BackgroundAdministration of green tea (GT) catechins has been reported to ensue antitumor activity in combination with chemotherapeutic drugs against different cancer types. Irinotecan (IRN) is a highly effective chemotherapeutic drug against various types of cancer including colon cancer along with its analogous dose-limiting side effects viz. diarrhea, neutropenia, leucopenia, and non-alcoholic fatty liver disease (NAFLD) as major toxicities.MethodsIn this study, we investigated the antitumor effects of GT alone or in combination with IRN in inflammation-associated colon cancer mouse model induced by azoxymethane (AOM) and dextran sulfate sodium (DSS). We also evaluated the effect of GT- on IRN-induced toxicity and histopathological alterations. Animals were divided into six groups (n = 5 per group). After induction of cancer model, animals were treated with GT and/or IRN. We observed the inflammation, tumor progression, and ameliorative effects of GT and IRN alone or in combination.ResultsBecause of antioxidant potential of GT, IRN-induced toxicity ameliorative effect of GT was also studied in combined treated groups. It was found that co-administration of IRN and GT significantly decreased number of tumors and simultaneously was found to ameliorate diarrhea along with leucopenia and neutropenia. Besides these, mitigation of adenomatous characters and NAFLD was also observed in the IRN- and GT-treated group when analyzed histologically.ConclusionsGT significantly reduced the toxicity induced by IRN in terms of diarrhea, neutropenia, leucopenia, and NAFLD and works as an effective anticancer agent as it mitigates histopathology of colon adenocarcinoma.Graphical abstract

Ex vivo dendritic cell-based (DC) vaccine pulsed with a low dose of liposomal antigen and CpG-ODN improved PD-1 blockade immunotherapy

Lack of pre-existing tumor infiltrated T cells resulting in resistance to programmed cell death protein 1 (PD-1) blockade therapies can be solved by combining with anti-cancer vaccines and CpG-ODN in increasing T cell expansion and infiltration. Therefore, we prepared an ex vivo dendritic cell-based (DC) vaccine pulsed with a low dose of either liposomal or non-liposomal gp100 antigen (2.8 µg) plus CpG-ODN (800 ng) formulations and evaluated its anti-tumor activity in combination with anti-PD-1 therapy. Our results showed a combination of liposomal peptide plus CpG-ODN pulsed DC with anti-PD-1 antibody was more efficacious, as evidenced by a significant increase in Teff/Treg TILs with a marked fourfold elevation of IFN-γ expression level in the tumor site of treated mice which reversed resistance to PD-1 blockade in a CD8 T cell-dependent manner. Furthermore, this combination also led to a remarkable tumor remission and prolonged survival rate in melanoma-bearing mice compared to non-liposomal peptide plus CpG-ODN or single-treated liposomal peptide formulations. Our results provide essential insights to devise combining regimens to improve the efficacy of immune checkpoint blockers even by a low dose of peptide and CpG-ODN.

P-135 Pembrolizumab/quavonlimab coformulation in combination with lenvatinib in advanced hepatocellular carcinoma: Phase 2 trial in progress

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death worldwide. Although advances in immunotherapy have improved clinical outcomes, the rate of death and disease is high, and there is an unmet need for new treatment approaches. PD-1/PD-L1 and CTLA-4 inhibitors alone or in combination have shown antitumor activity in advanced HCC. Additionally, lenvatinib, an inhibitor of vascular endothelial growth factor receptors 1-3, fibroblast growth factor receptors 1-4, platelet-derived growth factor receptor alpha, KIT, and RET, is a first-line treatment option in advanced HCC and has shown promising antitumor activity in combination with pembrolizumab in an early-stage study.

Abstract 1583: SEA-TGT is an empowered anti-TIGIT antibody that displays superior combinatorial activity with several therapeutic agents

Abstract TIGIT is an immunoregulatory receptor expressed on activated and memory T cells, Tregs, and NK cells. TIGIT binding to CD155 and CD112 on tumor cells drives an inhibitory signal resulting in decreased T cell functionality. TIGIT targeting has been reported to release these inhibitory signals, drive Treg depletion, augment CD8+ T cell generation, and promote anti-tumor responses. Anti-TIGIT therapies have come to prominence recently as new strategies for anti-cancer therapy particularly in combination with other immune checkpoint inhibitors because of their complementary mechanisms of action. We have recently developed an investigational anti-TIGIT monoclonal antibody that employs our proprietary sugar engineered antibody (SEA) technology to create a nonfucosylated antibody, termed SEA-TGT. In the present studies, we have expanded our investigation of SEA-TGT and compared it to other antibody formats to understand how differences in complementarity-determining regions (CDR) and backbone effect both in vitro activity and in vivo anti-tumor response. We also investigated how these differences affect the ability of anti-TIGIT mAbs to combine with other anti-tumor therapies. The nonfucosylated SEA-TGT demonstrates a unique activating to inhibitory FcγR binding profile. SEA-TGT demonstrates enhanced FcγRIIIA binding with concomitant reduction in inhibitory FcγRIIb receptor binding. This binding with SEA-TGT was distinct from standard IgG1 backbones and gains effector function modifications compared to other anti-TIGIT mAbs. The differential ability to engage activating vs. inhibitory Fcγ receptors translated into distinct differences in preclinical activity. The differences seen in vitro were recapitulated in vivo as SEA-TGT led to enhanced tumor activity in syngeneic tumor models. Anti-TIGIT treatments are being pursued clinically in combination with other therapeutic modalities, as such we evaluated treatment with the TIGIT mAbs with different effector function backbones with various other anti-tumor therapies. When used at sub-therapeutic doses, SEA-TGT exhibited greatly enhanced anti-tumor activity in combination with both checkpoint therapy as well as with an ICD inducing vc-MMAE antibody-drug conjugate. Collectively, these data continue to strengthen our findings that the nonfucosylated effector function enhanced backbone of SEA-TGT confers superior preclinical anti-tumor activity as a monotherapy agent and in combination with PD(L)1 agents and vc-MMAE ADCs. We have initiated a phase 1 trial testing the safety and activity of SEA-TGT alone and in combination with anti-PD-1 therapy in patients with advanced solid tumors and select lymphomas. Citation Format: Alyson Smith, Weiping Zeng, Sasha Lucas, Bryan Grogan, Amber Blackmarr, Serena Wo, Scott Peterson, Shyra Gardai. SEA-TGT is an empowered anti-TIGIT antibody that displays superior combinatorial activity with several therapeutic agents [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1583.

Abstract 1883: Mechanism of action and biomarker strategy for HFB200301, an anti-TNFR2 agonist antibody for the treatment of cancer

Abstract Despite the success of immune check point inhibition, identification of other pathways capable of modulating the immune response against the tumor remains challenging. T-cell co-stimulation has been investigated with limited clinical success so far due in part to the fine tuning required for agonist antibodies against those co-stimulatory receptors and to the lack of biomarkers to facilitate the selection of patients likely to benefit from T-cell co-stimulation. TNFR2 belongs to the TNFR family of costimulatory molecules, and its expression on tumor infiltrating lymphocytes across a wide range of tumors make it an attractive target for T-cell co-stimulation. Recently, we identified HFB200301, an anti-TNFR2 antibody with Fc-independent agonist activity that does not block TNFR2 interaction with TNFα. HFB200301 activates CD4+, CD8+ T cells, and NK cells in vitro. In vivo, HFB200301 demonstrated potent single agent anti-tumor activity in syngeneic tumor models and can further increase the antitumor activity in combination with PD-1 blockade. To understand the immunological basis for the anti-tumor efficacy of HFB200301, we investigated the pharmacodynamic effects of HFB200301 in syngeneic mouse tumor models, including immuno-phenotyping and receptor occupancy of tumor infiltrating cells. In hTNFR2 knock-in mice bearing MC38 tumors, HFB200301 induces expansion of CD4+ and CD8+ T cells, and NK cells in the tumor micro-environment without affecting regulatory T cell numbers. We also demonstrate that the anti-tumor efficacy of HFB200301 is correlated with receptor occupancy and circulating soluble TNFR2 in a dose-dependent manner in this model. To discover predictive biomarkers of response to HFB200301, we used primary tumor samples and our proprietary Drug Intelligent Science (DIS™) single-cell platform to establish an immune-related signature. Single-cell RNA sequencing and clonotype barcoding of ex-vivo tumor cultures treated with HFB200301 were used to identify unique T cell profiles with a T cell centric gene panel. These unique T cell profiles may help identifying patients more likely to respond to HFB200301 treatment. In summary, HFB200301 exhibits a unique mechanism of action mainly relying on its agonistic activity on several effector cell types in tumor micro-environment that we expect will benefit a patient population selected with a unique biomarker signature. HFB200301 is currently in preclinical development and a biomarker-driven Phase 1 clinical study is projected for 2021. Citation Format: Shuo Wei, Ross Fulton, Yun-Yueh Lu, Qian Zhang, He Zhou, Andreas Raue, Mingjie Chen, Wenhua Xu, Xing Cai, Juliana Crivello, Zachary Duda, Zhiyuan Wang, Rebecca Silver, Alexandra Staskus, Charina Ortega, Sami Ellouze, Carine George, Sophie Foulon, Dean Lee, Monika Manne, Nicola Beltraminelli, Jinping Gan, Francisco Adrian, Liang Schweizer, Jennifer Watkins-Yoon. Mechanism of action and biomarker strategy for HFB200301, an anti-TNFR2 agonist antibody for the treatment of cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1883.

Abstract 1414: Effect of E7090, an FGFR1-3 selective inhibitor, on resistance to a CDK4/6 inhibitor and endocrine therapy in ER(+)/HER2(-) breast cancer preclinical models

Abstract Introduction: The fibroblast growth factor receptor (FGFR) signaling has a crucial role in proliferation, survival, migration, and drug resistance of cancer cells, as well as tumor angiogenesis. Moreover, gene alterations of FGF/FGFR were reported after treatment of a CDK4/6 inhibitor and endocrine therapy (ET) in ER(+)/HER2(-) breast cancer (BC) patients, suggesting FGF/FGFR signaling mediates resistance to these therapies. E7090, an orally available FGFR1-3 selective inhibitor, is currently under evaluation in a Phase 2 study in patients with unresectable advanced or metastatic cholangiocarcinoma with FGFR2 gene fusion (NCT04238715), and a Phase 1 study as a monotherapy or in combination with fulvestrant (FUL) or exemestane for ER(+)/HER2(-) BC patients (NCT04572295). In this study, we present the roles of FGF/FGFR signaling in resistance to a CDK4/6 inhibitor and/or ET, and activities of E7090 on drug resistance in preclinical ER(+)/HER2(-) BC cell lines and PDx models. Results: Antitumor activities of E7090 (25 or 50mg/kg, Q1Dx14 or x21, p.o.) were evaluated using five ER(+)/HER2(-) BC PDx models, OD-BRE-0438, -0450, -0188, -0704, and IM-BRE-556 with or without prior treatment of FUL (5 mg/mouse, Q7Dx2, s.c.)+palbociclib (PAL, 100mg/kg, Q1Dx14, p.o.). Among them, OD-BRE-0438 and -0704 showed higher sensitivities to E7090 with prior FUL+PAL than without it, and E7090 showed tumor regression in the OD-BRE-0438 model only with prior FUL+PAL. In these two models, FUL+PAL treatment upregulated expressions of several FGF ligands mRNA (qPCR) and FGFRs protein (IHC) in tumors. To evaluate the activities of FGF/FGFR signaling on sensitivities to FUL or FUL+PAL, in vitro cell proliferation assay using ER(+)/HER2(-) BC cell lines, MCF-7, ZR-75-1, and HCC1428 were performed in the presence of FGF2 and FGF10, and decreased sensitivities to FUL or FUL+PAL were observed. Furthermore, co-treatment with E7090 restored the sensitivity to those drugs in cultured cell lines. In consistent with in vitro results, FUL in combination with E7090 showed a combination antitumor activity in the OD-BRE-0438 model, in which expressions of several FGF ligands mRNA and FGFR2 protein in tumors showed a tendency of upregulation by FUL. Conclusion: In ER(+)/HER2(-) BC PDx models, FGFs/FGFRs expression in tumors were induced by treatment of FUL and/or PAL, and antitumor activity of E7090 was enhanced with prior FUL+PAL. In vitro study using cultured ER(+)/HER2(-) BC cell lines indicated that sensitivity against FUL or FUL+PAL was decreased by FGFR activation. Furthermore, a combination antitumor activity of E7090 and FUL was observed in the OD-BRE-0438 model. These data suggest that activation of FGF/FGFR signaling confer the resistance to a CDK4/6 inhibitor and/or ET, and E7090 shows antitumor activity against ER(+)/HER2(-) BC with prior a CDK4/6 inhibitor and/or ET. Citation Format: Satoshi Kawano, Sayo Fukushima, Kyoko Nishibata, Ryu Gejima, Yuki Niwa, Yasuhiro Funahashi, Saori Watanabe Miyano. Effect of E7090, an FGFR1-3 selective inhibitor, on resistance to a CDK4/6 inhibitor and endocrine therapy in ER(+)/HER2(-) breast cancer preclinical models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1414.

ALX148 Is a High Affinity Sirpα Fusion Protein That Blocks CD47, Enhances the Activity of Anti-Cancer Antibodies and Checkpoint Inhibitors, and Has a Favorable Safety Profile in Preclinical Models

CD47 is a widely expressed cell surface protein thought to function as an immune checkpoint in cancer. CD47 binds SIRPα on myeloid cells, suppressing tumor cell phagocytosis and other innate immune functions. CD47-SIRPα signaling has also been implicated in the suppression of adaptive antitumor responses, but the relevant cellular functions have yet to be elucidated. Abundant CD47 expression has been observed in tumors and may aid tumor cells in the evasion of immune surveillance.Therapeutic blockade of the CD47 pathway may stimulate antitumor immunity and improve cancer therapy. To this end, the novel CD47-blocking molecule ALX148 was generated by fusing a modified SIRPα N-terminal D1 domain to an inactive Fc. Surface plasmon resonance analysis demonstrated that ALX148 binds human and murine CD47 with high affinity, with respective KDs of 0.14 nM and 12 nM. ALX148 also bound multiple CD47-expressing cell populations in flow cytometry assays. ALX148 blocks the interaction between CD47 and wild type SIRPα, enhancing antibody-dependent phagocytosis of hematologic tumor cell lines by daratumumab, rituximab, and obinutuzumab.ALX148 increased the efficacy of antibodies targeting hematologic tumors, such as rituximab and obinutuzumab, in xenograft models of hematologic malignancies. Because ALX148 also binds murine CD47 with high affinity, syngeneic tumor models were used to examine the activity of ALX148 in the context of an intact immune system. ALX148 enhanced the antitumor activities of checkpoint inhibitors. Specifically, the immune response induced by ALX148 bridged innate and adaptive immune responses. ALX148 stimulated antitumor properties of innate immune cells, promoting dendritic cell activation and a shift of tumor associated macrophages toward a proinflammatory phenotype. ALX148 in combination with checkpoint inhibitors caused increased cytotoxic T cell infiltrates, with greater CD8 to Treg ratios, and greater amounts of interferon gamma production by T cells in both tumors and the spleen. These findings reveal multiple mechanisms by which adaptive immunity is stimulated by CD47 blockade.Notably, ALX148 had no adverse effect on CD47-expressing red blood cells and platelets. In vitro, ALX148 did not induce erythrocyte hemagglutination. In non-human primate toxicology studies, ALX148 multi-dose administration was well tolerated and did not affect levels of circulating red blood cells, white blood cells, or platelets. This is in contrast to other published CD47-blocking molecules, which have caused anemia and thrombocytopenia in preclinical and clinical studies. Thus, ALX148 may have minimal hematologic toxicity in humans.ALX148 enhances adaptive and innate immune responses, demonstrates enhanced preclinical anti-tumor activity in combination with multiple standard of care cancer therapies, and is well tolerated. It is currently being investigated in a first-in-patient, phase 1 dose escalation/expansion, multi-center study in patients with advanced solid tumors and lymphoma. (NCT03013218). DisclosuresKauder:Alexo Therapeutics: Employment. Kuo:Alexo Therapeutics: Employment. Chen:Alexo Therapeutics: Employment. Harrabi:Alexo Therapeutics: Employment. Rocha:Alexo Therapeutics: Employment. Doyle:Alexo Therapeutics: Employment. Bollini:Alexo Therapeutics: Employment. Han:Alexo Therapeutics: Employment. Sangalang:Novartis: Employment; Alexo Therapeutics: Employment. Sim:Alexo Therapeutics: Employment. Randolph:VenBio: Consultancy; Carrick Therapeutics: Membership on an entity's Board of Directors or advisory committees; Alexo Therapeutics: Employment. Pons:Alexo Therapeutics: Employment, Equity Ownership. Wan:Alexo Therapeutics: Employment; Pfizer: Equity Ownership.

Trastuzumab deruxtecan (T-DXd) combinations in patients with HER2-positive advanced or metastatic breast cancer: A phase 1b/2, open-label, multicenter, dose-finding and dose-expansion study (DESTINY-Breast07).

TPS1096 Background: HER2-targeted therapies have improved survival in patients (pts) with HER2+ advanced/metastatic breast cancer (mBC) but challenges remain, including resistance to current HER2-targeted therapies. Also, additional treatment options are needed in pts with brain metastases (BM). In the phase 2 DESTINY-Breast01 trial, T-DXd demonstrated efficacy, with an objective response rate (ORR) of 61.4% and median progression-free survival (mPFS) of 19.4 mo in pts with previously treated HER2+ advanced/mBC (Modi SABCS 2020); data from an earlier cutoff of this trial supported approval of T-DXd in the US, Europe, and Japan. In a subgroup analysis of 24 pts with stable BM, T-DXd showed preliminary efficacy, with mPFS of 18.1 mo (Jerusalem ESMO Breast Cancer 2020). Here, we describe a phase 1b/2 trial evaluating the safety and preliminary antitumor activity of T-DXd monotherapy and combinations in pts with HER2+ advanced/mBC, including pts with stable and active BM. Methods: DESTINY-Breast07 (NCT04538742) is a global, multicenter, open-label, phase 1b/2 trial designed to evaluate the safety, tolerability, and preliminary antitumor activity of T-DXd monotherapy and combinations in pts with HER2+ advanced/mBC. This study consists of a T-DXd monotherapy module (module 0) and 5 combination modules of T-DXd plus (1) durvalumab, (2) pertuzumab, (3) paclitaxel, (4) durvalumab + paclitaxel, or (5) tucatinib, all in pts with no or stable BM. Two additional modules consisting of (6) T-DXd + tucatinib and (7) T-DXd monotherapy will include pts with untreated BM not requiring local therapy or previously treated BM that have progressed since local therapy (active BM). The need for chronic steroids or local therapy to manage BM symptoms is exclusionary. Modules 2 to 5 will each consist of 2 parts: dose finding (part 1) and dose expansion (part 2). Modules 0, 1, 6, and 7 will include part 2 only. Part 1 of individual modules will enroll pts who have had disease progression while receiving ≥1 prior line of therapy in the metastatic setting. In part 2, pts who have received no prior therapy (modules 0 to 5) or ≤1 prior therapy (modules 6 to 7) for metastatic disease will be randomized to receive a T-DXd combination regimen or monotherapy. The primary endpoints are determination of the recommended phase 2 doses (part 1 only) and safety and tolerability of T-DXd and combinations (parts 1 and 2). Secondary endpoints include ORR, PFS, PFS2, duration of response (DoR), and overall survival (all assessed in part 2 only) and pharmacokinetics and immunogenicity (parts 1 and 2). To assess central nervous system (CNS) activity, exploratory endpoints were added, including CNS-ORR, CNS-DoR, and CNS-PFS (by RECIST version 1.1 and RANO-BM criteria) as well as cognitive and symptom assessment using CANTAB, MDASI-BT, and NANO. Clinical trial information: NCT04538742 .

Surufatinib in combination with toripalimab in patients with advanced neuroendocrine carcinoma: Results from a multicenter, open-label, single-arm, phase II trial.

e16199 Background: Patients with advanced neuroendocrine carcinoma (NEC) have a poor prognosis and limited treatment option after first-line treatment. Surufatinib, a multi-kinase inhibitor of VEGFR 1-3, FGFR 1 and CSF-1R, has been approved in patients with advanced or metastatic extra-pancreatic neuroendocrine tumors in China. Toripalimab is a monoclonal humanized IgG4 PD-1 antibody. Surufatinib modulates tumor immune microenvironment and has shown promising antitumor activity in combination with toripalimab in solid tumors, including neuroendocrine tumor and neuroendocrine carcinoma. Herein, we reported the efficacy and safety of surufatinib in combination with toripalimab in a cohort of advanced NEC patients. Methods: The multicenter, open-label, single-arm phase II clinical trial enrolled advanced NEC patients refractory to first-line chemotherapy, and received surufatinib 250 mg once a day orally plus toripalimab 240 mg intravenously on day 1 of a 21-day cycle. The primary end point is objective response rate (ORR) per RECIST 1.1. Results: Twenty-one patients enrolled and received combination therapy. At data cut-off (December 31, 2020), the average treatment cycles were 5.1±3.69 for surufatinib and 5.0±3.68 for toripalimab. Among 20 tumor evaluable patients, 4 patients achieved confirmed PR and 10 patients achieved stable disease. The ORR and disease control rate (DCR) are 20 % (95%CI: 5.7%-43.7%) and 70% (95%CI: 45.7%-88.1%) respectively. The median PFS is 3.94 months (95%CI: 1.31- unknown). OS is not mature till data cut-off. Adverse events (AEs) reported as related to treatment (TRAE) occurred in 100% of patients, of which Grade≥3 TRAEs occurred in 33.3% of patients. The reported Grade≥3 TRAEs were hypertension in 2 (9.5%) patients, and upper abdominal pain, oral mucositis, neutrophil count decreased, leukocyte count decreased, dermatitis, anemia and backache in 1 (4.8%) patient each. Immune related Grade ≥3 AEs, Gamma-glutamyl transpeptidase increased and dermatitis, occurred in 2 (9.5%) patients, respectively. TRAE caused surufatinib or toripalimab interruption occurred in 6 (28.6%) and 4 (19%) patients respectively. There were neither serious AEs nor AEs inducing treatment discontinuations or deaths. Conclusions: As there is no standard second-line treatment, this combination of surufatinib and toripalimab might offer a new promising choice to treat NEC as second-line treatment due to good efficacy and manageable treatment related toxicities. Clinical trial information: NCT04169672.