Supplementary Figure S1 shows mean (+SD) plasma concentrations of nemtabrutinib vs time following single (C1D1) oral doses of MK-1026 (linear and semi-log plots) nM

Abstract Nemtabrutinib is an orally bioavailable, reversible inhibitor of Bruton tyrosine kinase (BTK) and C481S mutant BTK. We evaluated the safety, pharmacology, and antitumor activity of nemtabrutinib in relapsed/refractory hematologic malignancies. Forty-eight patients with chronic lymphocytic leukemia (CLL), B-cell non–Hodgkin lymphoma (NHL), or Waldenström macroglobulinemia (WM), relapsed/refractory after ≥2 prior therapies were enrolled in the open-label, single-arm, phase I MK-1026-001 study (NCT03162536) to receive nemtabrutinib 5 to 75 mg once daily in 28-day cycles. Dose finding progressed using a 3 + 3 dose escalation design. Primary endpoints were safety and the recommended phase II dose (RP2D). Among 47 treated patients, 29 had CLL, 17 had NHL, and 1 had WM. Grade ≥3 treatment-emergent adverse events occurred in 37 (89%), most commonly neutropenia (11; 23.4%), febrile neutropenia (7; 14.9%), and pneumonia (7; 14.9%). The RP2D was 65 mg daily. An overall response rate of 75% was observed in patients with CLL at 65 mg daily. Significance: This first-in-human phase I study demonstrates the safety and preliminary efficacy of nemtabrutinib in patients with relapsed/refractory B-cell malignancies. These data support further exploration of nemtabrutinib in larger clinical studies. This article is featured in Selected Articles from This Issue, p. 5

Abstract Background: Dysregulation of the PI3K/AKT signaling pathway is associated with various types of cancers. AKT can be activated through activated receptor tyrosine kinases, gain-of-function mutations of PIK3CA, PTEN deficiency, or AKT amplification or activating mutations such as AKT1-E17K. It has been shown that the PI3K/AKT pathway has contributed to the resistance of conventional chemotherapy, radiation and other targeted therapies. AKT inhibitors have been extensively studied in the clinic and enhance the effects of targeted therapy, chemotherapy and radiation therapy. ARQ 751 is a second-generation AKT inhibitor, which has distinct physico-chemical properties as compared to ArQule’s first-generation inhibitor, miransertib (ARQ 092). ARQ 751 is currently in a phase 1 clinical study in molecularly defined cancer patients. In this study, we assessed the combined effect of ARQ 751 with PARP inhibitors, CDK4/6 inhibitors, an estrogen receptor antagonist and a chemotherapeutic agent both in vitro and in vivo. Methods: In vitro anti-proliferative studies were performed using MTS or Celltiter-Glo as either single agents or in combination with other therapeutic agents. The combination index was calculated based on Cho-Talalay method. In vivo efficacy was tested in patient-derived breast cancer tumors bearing AKT1-E17K mutations and breast cancer cells with PIK3CA mutations. Reverse phase protein arrays (RPPA) were performed on xenograft tumor tissues. Results: ARQ 751 in combination with the PARP inhibitors exhibited enhanced anti-proliferative activity in MDA-MB-468 breast cancer cells. The combination of ARQ 751 and olaparib also suppressed anchorage-independent growth in MDA-MB-231 and HCC1143 cells. In combination with the CDK4/6 inhibitor, ribociclib, ARQ 751 demonstrated superior cell growth inhibition in comparison to the single agents. A synergistic effect was observed at a majority of combination concentration points. In the in vivo efficacy study in a xenograft model with HCC-1954 breast cancer cells, combined treatment of ARQ 751 at 25 mg/kg and paclitaxel at 15 mg/kg showed enhanced antitumor activity with TGI of (90%) in comparison to ARQ 751 alone (46%) or paclitaxel alone (44%) after 3-weeks of treatment. Furthermore, an estrogen receptor positive patient-derived tumor xenograft model harboring the AKT1-E17K mutation was used to assess the effect of ARQ 751 in combination with either fulvestrant or palbociclib or both agents. Combination of ARQ 751 at 25 mg/kg with either fulvestrant at 2.5 mg/kg or palbociclib at 50 mg/kg exerted tumor growth inhibition of 91% or 93%, respectively, as compared to 69% for ARQ 751, 68% for fulvestrant and 38% for palbociclib. When the three agents were combined, tumor regression (TGI >100%) was observed. In order to understand the molecular mechanism involved in the superiority of the combined effect, a RPPA study from xenograft tumor tissues is being performed to assess any alterations in several key pathways. Conclusions: ARQ 751, a highly potent and selective next-generation AKT inhibitor, is combinable with various therapeutic agents including PARP inhibitors, an ER antagonist, CDK4/6 inhibitors, and a chemotherapeutic agent, in vitro and in vivo. The data support the rationale for testing these combinations in the clinic. Citation Format: Yi Yu, Alden Harring, Eva Volckova, Ronald E Savage, Brian Schwartz. In vitro and in vivo combination of ARQ 751 with PARP inhibitors, CDK4/6 inhibitors, Fulvestrant and Paclitaxel [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr C076. doi:10.1158/1535-7163.TARG-19-C076

Abstract Background: AKT, a critical node in the PI3K/AKT/mTOR pathway, is one of the most frequently activated protein kinases in human cancers. ARQ 751 is a potent and highly selective pan-AKT inhibitor against AKT1, AKT2, and AKT3, and is currently in a phase 1b clinical trial as a single agent, or combination with paclitaxel or fluvestrant. Inhibition of the PI3K/AKT pathway is known to cause increases in serum glucose and insulin in patients. Recent advances in next generation sequencing technologies are providing physicians and researchers with access to tumor genomic data, including circulating tumor DNA (ctDNA), to support and evaluate treatment strategies. Methods: Samples were collected for pharmacokinetic, pharmacodynamic, and genetic analysis. PK samples were collected on Days 1 and 22 to generate PK profiles. Samples were analyzed, and PK parameters generated, including Cmax, AUC, and t1/2 (where possible). Biomarkers evaluated for target engagement were serum glucose and insulin. Finally, whole blood was collected and mutational status of ctDNA was analyzed using Guardant360. Results: The Recommended Phase 2 Dose (RP2D) of ARQ 751 was determined to be 75 mg QD, with a mean Cmax of 263 ng/mL and an AUClast 2240 h*ng/mL on Day 22. Changes in both serum insulin and glucose were observed, and these increases correlated with ARQ 751 exposure. In patients with detectable levels of ctDNA (matching tumor); 6 (1PR, 4SD, 1PD) showed a decrease between Cycle 1, Day 1 and Cycle, 2 Day 1, and 3 showed an increase (1PR, 1SD, 1 PD). Conclusions: Preliminary PK, PD, and ctDNA data support the selection of 75 mg QD as the RP2D for ARQ 751. ARQ 751 plasma levels at this dose produced increases in both serum insulin and glucose, confirming target engagement. Additionally, an evaluation of a limited set of pre and post treatment ctDNA data provides interesting new insights on patient’s responses to therapy. Additional data to be presented at the meeting. Citation Format: Shubham Pant, Maria Lamar, Julia Kazakin, Ronald Savage, Brian Schwartz, terence hall. The use of biomarkers and ctDNA in a phase 1 trial of ARQ 751 [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr A034. doi:10.1158/1535-7163.TARG-19-A034

Background:The BTK inhibitor ibrutinib has been approved for multiple indications based on marked treatment benefit in B cell lymphoma/leukemia. Although ibrutinib provides durable, disease control, resistance is emerging as an area of unmet medical need. ARQ 531 is a reversible ATP competitive inhibitor of BTK that inhibits both wild type and ibrutinib‐resistant BTK‐C481S mutant CLL cells and has demonstrated antitumor activity in CLL, Richter's transformation, and DLBCL mouse models.Aims:The primary objectives of the clinical study are to assess the safety and tolerability of ARQ 531, and to determine the recommended Phase 2 dose and schedule. The secondary objectives are to assess the pharmacokinetic (PK) profile, pharmacodynamic (PD) activity, and preliminary evidence of anti‐tumor activity.Methods:This is a first in human, Phase 1 dose escalation study in patients with relapsed/refractory CLL/SLL, B‐cell NHL or Waldenstrom's macroglobulinemia who received at least 2 prior lines of systemic therapy. Prior therapy must have included a BTK inhibitor. Dose escalation was performed according to a 3+3 study design. Treatment emergent adverse events (TEAEs) were assessed per NCI CTCAE v.4.03. Tumor responses were evaluated per disease specific guidelines.Results:As of February 15, 2019, a total of 26 patients have been treated: CLL/SLL (n = 19), DLBCL (n = 2), FL (n = 4), MCL (n = 1). Baseline demographics were: median age 65 (48–82) years, male/female 24/2 and median number of prior lines of therapy 5 (range 2–12). Enrolled patients received ARQ 531 orally once daily in 28‐day cycles at doses of 5, 10, 15, 20, 30, 45 and 65 mg QD.Drug related TEAEs that occurred in ≥2 subjects were nausea (15.4%), neutrophil count decreased (11.5%), constipation, diarrhea, vomiting, fatigue, decreased appetite, arthralgia, dizziness, dysgeusia and headache (7.7% each). The majority of the TEAEs were grade 1 or 2. Drug related grade 3 or worse TEAEs included neutrophil count decreased (11.5%), platelet count decreased (3.8%), lipase increased (3.8%), and rash (3.8%). The only grade 3 TEAE of rash occurred in one subject treated with 65 mg QD and was a SAE and assessed as a dose limiting toxicity (DLT). The 65 mg QD cohort was expanded to enroll more subjects. The maximum tolerated dose (MTD) has not been reached.Preliminary PK data show that cohorts receiving ≥ 45 mg QD of ARQ 531 exhibited steady‐state trough concentrations (Cmin) of above 1 micromolar; the estimated plasma half‐life generally ranged from 20–30 hours and was associated with complete pBTK inhibition and CCL3 suppression. Furthermore, increasing tumor suppression seen at higher dose levels was also correlated with higher Cmin concentrations.Among the 14 subjects who have received doses ≥ 45 mg QD, either as starting dose or dose escalated, 9 were evaluable for response (on study treatment for at least one cycle and had at least one post‐treatment tumor measurement). Among them, 2 patients had partial responses (1 CLL with BTK C481S mutation who had received 3 prior lines of therapy including acalabrutinib, 1 FL who had received 3 prior lines of therapy and is on study for >83 weeks) and 5 achieved stable disease with tumor reduction between 30% to 49% with median lines of prior therapy of 9.Summary/Conclusion:Based on the emerging data, ARQ 531 has a manageable safety profile and shows preliminary anti‐tumor activity as a single agent in heavily treated B‐cell NHL and BTK inhibitor resistant CLL patients. Dose escalation continues, updated safety, PK, biomarker and anti‐tumor activity data will be presented at the meeting.

Proteus syndrome is a life-threatening segmental overgrowth syndrome caused by a mosaic gain-of-function AKT1 variant. There are no effective treatments for Proteus syndrome. Miransertib is an AKT1 inhibitor that, prior to this study, has been evaluated only in adult oncology trials. We designed a non-randomized, phase 0/1 pilot study of miransertib in adults and children with Proteus syndrome to identify an appropriate dosage starting point for a future efficacy trial using a pharmacodynamic endpoint. The primary endpoint was a 50% reduction in the tissue levels of AKT phosphorylation from biopsies in affected individuals. We also evaluated secondary efficacy endpoints. We found that a dose of 5 mg/m(2)/day (1/7 the typical dose used in oncology) led to a 50% reduction in phosphorylated AKT (pAKT) in affected tissues from five of six individuals. This dose was well tolerated. Two of the six efficacy endpoints (secondary objectives) suggested that this agent may be efficacious. We observed a decrease in a cerebriform connective tissue nevus and a reduction in pain in children. We conclude that 5 mg/m(2)/day of miransertib is an appropriate starting point for future efficacy trials and that this agent shows promise of therapeutic efficacy in children with Proteus syndrome.

Introduction: Resistance to covalent BTK inhibitors such as ibrutinib and acalabrutinib is a common mechanism of resistance that portends a poor long-term clinical outcome. ARQ 531 is a potent, reversible inhibitor of both wild type and ibrutinib-resistant C481S-mutant BTK. ARQ 531 suppresses oncogenic BCR signaling in CLL cells resistant to ibrutinib and has demonstrated antitumor activity superior to ibrutinib in CLL, Richter's transformation, and DLBCL mouse models. Methods: The primary objectives of the clinical study were to assess the safety and tolerability of ARQ 531, and to determine the recommended Phase 2 dose (RP2D) and schedule. The secondary objectives were to assess the pharmacokinetic (PK) profile, pharmacodynamic (PD) activity, and preliminary evidence of anti-tumor activity. Eligible patients had relapsed/refractory CLL/SLL, B-cell NHL or Waldenstrom's macroglobulinemia, had received at least 2 prior lines of systemic therapy and had good organ function including creatinine clearance ≥ 60 mL/min as estimated by the Cockcroft-Gault equation or by 24-hour urine collection, absolute neutrophil count ≥ 1000/µL, platelet count ≥ 50,000/µL and hemoglobin ≥ 8.0 g/dL. Prior therapy for CLL must have included an irreversible BTK inhibitor. Dose escalation was performed according to a 3+3 study design. Treatment emergent adverse events (TEAEs) were assessed per NCI CTCAE v.4.03. Tumor responses were evaluated per disease specific guidelines. Results: As of July 19, 2019, a total of 40 patients have been treated: CLL/SLL (n=26), Richter's transformation (n=6), DLBCL (n=3), FL (n=4), MCL (n=1). Baseline demographics were: median age 65.5 (range 47-82) years, male/female 36/4 and median number of prior lines of therapy 4 (range 2-12). BTK-C481S mutation was documented in 22/26 (85%) CLL patients. Enrolled patients received ARQ 531 orally once daily, continuously, in 28- day cycles at doses of 5, 10, 15, 20, 30, 45, 65 and 75 mg QD. The most common drug-related TEAEs that occurred in > 2 patients were nausea (n=4), diarrhea (n=4), fatigue (n=3), neutrophil count decreased (n=3), dysgeusia (n=3) and rash (n=3). The majority of the drug-related TEAEs were grade 1 or 2. Drug-related grade 3 or 4 TEAEs included neutrophil count decreased (n=3), as well as febrile neutropenia, cellulitis, platelet count decreased, lipase increased, and rash (one each). One subject treated at 65 mg experienced a DLT of grade 3 rash. The 65 mg cohort was expanded to a total of 10 patients, and no other DLTs were observed. At the 75 mg QD dose level (n =4), drug-related grade 2 adverse events were reported which led to dose reduction to 65 mg QD (n=3) or treatment discontinuation (n=1). Preliminary PK data show that patients receiving ARQ 531 at 65 mg QD exhibit steady-state trough concentrations (Cmin) above 1 µM; the estimated plasma half-life generally ranged from 20-30 hours and was associated with complete pBTK inhibition. Clinical responses to ARQ 531 were observed in multiple patients with B-cell malignancies. Ten partial responses (PRs) were achieved mainly in the higher dose cohorts, and included patients with CLL (n=7), Richter's transformation (n=1), DLBCL (n=1) and follicular lymphoma (n=1). Of the 7 CLL patients who attained PRs, 5 were initiated at 65 mg, 1 was initiated at 45 mg and was dose escalated to 65 mg and 1 was initiated at 75 mg and dose reduced to 65 mg. Together, the safety, PK/PD and clinical activity results suggest that ARQ 531 at 65 mg QD is safe, well tolerated and has clear signs of anti-tumor efficacy. Thus, 65 mg QD dose has been selected as the RP2D in patients with B-cell malignancies. Conclusion: ARQ 531 has a manageable safety profile and shows anti-tumor activity as single agent therapy in heavily pre-treated patients with B-cell NHL and in patients with CLL resistant to covalent BTK inhibitor. The Phase 1 dose escalation portion of this study is complete. Enrollment of patients with multiple B-cell malignancies is ongoing at 65 mg QD in the phase 1b expansion portion of the study. Updated safety, PK, biomarker and anti-tumor activity data will be presented. Disclosures Woyach: Morphosys: Research Funding; Verastem: Research Funding; Loxo: Research Funding; Janssen: Consultancy, Research Funding; Pharmacyclics LLC, an AbbVie Company: Consultancy, Research Funding; AbbVie: Research Funding; Karyopharm: Research Funding. Stephens:Karyopharm: Research Funding; Gilead: Research Funding; Acerta: Research Funding. Flinn:F. Hoffmann-La Roche Ltd: Research Funding; TG Therapeutics, Trillum Therapeutics, Abbvie, ArQule, BeiGene, Curis, FORMA Therapeutics, Forty Seven, Merck, Pfizer, Takeda, Teva, Verastem, Gilead Sciences, Astra Zeneca (AZ), Juno Therapeutics, UnumTherapeutics, MorphoSys, AG: Research Funding; AbbVie, Seattle Genetics, TG Therapeutics, Verastem: Consultancy; TG Therapeutics, Trillum Therapeutics, Abbvie, ArQule, BeiGene, Curis, FORMA Therapeutics, Forty Seven, Merck, Pfizer, Takeda, Teva, Verastem, Gilead Sciences, Astra Zeneca (AZ), Juno Therapeutics, UnumTherapeutics, MorphoSys, AG: Research Funding; Acerta Pharma, Agios, Calithera Biosciences, Celgene, Constellation Pharmaceuticals, Genentech, Gilead Sciences, Incyte, Infinity Pharmaceuticals, Janssen, Karyopharm Therapeutics, Kite Pharma, Novartis, Pharmacyclics, Portola Pharmaceuticals: Research Funding. Bhat:Pharmacyclics: Consultancy; Janssen: Consultancy. Savage:ArQule, Inc.: Employment. Chai:ArQule, Inc.: Employment. Eathiraj:ArQule, Inc.: Employment. Granlund:ArQule, Inc.: Employment. Schwartz:ArQule, Inc.: Employment. Byrd:Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Acerta: Research Funding; Novartis: Other: Travel Expenses, Speakers Bureau; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Genentech: Research Funding; Acerta: Research Funding; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Ohio State University: Patents & Royalties: OSU-2S; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; Genentech: Research Funding; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; Acerta: Research Funding; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; BeiGene: Research Funding; BeiGene: Research Funding; Novartis: Other: Travel Expenses, Speakers Bureau; BeiGene: Research Funding; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Novartis: Other: Travel Expenses, Speakers Bureau; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Ohio State University: Patents & Royalties: OSU-2S; Ohio State University: Patents & Royalties: OSU-2S; Genentech: Research Funding.

Abstract Background: ARQ 531 is a novel, ATP competitive reversible inhibitor Bruton's tyrosine kinase (BTK). BTK is a key regulator of the B cell receptor (BCR) signaling pathway that mediates signaling from the cell surface to the cytoplasm and into the nucleus. ARQ 531 is not metabolized by any of the major drug metabolizing CYP450 enzymes. Here we report pharmacokinetic profile of ARQ 531 in a phase I study evaluating safety, pharmacokinetics and pharmacodynamics activity and clinical activity of ARQ 531 in selected subjects with relapsed/refractory B-cell malignancies. Preclinical studies in rats, dogs and monkeys are also described. Methods: Oral and intravenous single dose pharmacokinetic studies of ARQ 531 were conducted in rats, dogs, and monkeys to determine oral bioavailability and drug exposure. In a standard ‘3+3' dose-escalation study design, ARQ 531 was given orally once per day beginning at 5 mg/dose and escalating for 4 weeks [NCT03162536]. Plasma samples were collected to determine ARQ 531 concentrations and whole blood / PBMCx to quantify pBTK inhibition. Plasma samples from each species were analyzed by liquid chromatography-mass spectrometry/ mass spectrometry (LC-MS/MS). Results: Consistent with preclinical studies, patients enrolled in the phase I study showed favorable exposures, the steady state peak to trough ratio was generally 3:1 or lower. ARQ 531 had an elimination half-life at steady state of ~24 hr and Cmax occurred 2 to 3 hours after dosing. Pharmacodynamic changes included suppression of BTK phosphorylation. No drug related AEs or DLTs have been observed thus far in the study. Conclusions: ARQ 531 demonstrates a favorable PK profile in humans supporting once daily dosing. Sufficient plasma levels are attained and high levels of pBTK inhibition in peripheral blood can be achieved following oral dosing. Additional dose and schedule evaluations continue, and updated clinical and biomarker results will be presented. Citation Format: Terence Hall, Yi Yu, Sudharshan Eathiraj, Deborah Stephens, Ian Flinn, Jennifer Woyach, Brian Schwartz, Ronald E. Savage. ARQ 531, a novel and reversible inhibitor of Bruton's tyrosine kinase, displays favorable oral bioavailability and exposure in patients with B-cell malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-018.

Abstract Background: Fibroblast growth factors (FGFs) and their receptors (FGFRs) play important roles in cell proliferation, cell differentiation, cell migration, cell survival, protein synthesis, and angiogenesis. The FGFR family consist of four genes encoding tyrosine kinase receptors (FGFR1, FGFR2, FGFR3, and FGFR4). Dysregulation of FGFR signaling has been implicated in a number of developmental syndromes as well as cancers, e.g., intrahepatic cholangiocarcinoma (iCCA), squamous non-small cell lung cancer, small cell lung cancer, gastric, liver, breast, ovarian, endometrial, and bladder carcinomas, fueling significant interest in FGFRs as targets for therapeutic intervention. In human cancers, FGFRs have been found to be dysregulated by multiple mechanisms, including aberrant expression, mutations, chromosomal rearrangements, and amplifications. Members of the FGF19 ligand subfamily, FGFs 19, 21 and 23, are involved in the regulation of bile acid synthesis, glucose and lipid metabolism, and phosphate homeostasis, respectively. Unlike other FGFR ligands that act locally, the FGF19 subfamily circulate throughout the body, and can act as endocrine hormones at organs distant from their site of synthesis. The wide circulation of FGFs 19, 21, 23 makes them excellent potential biomarkers for FGFR inhibition. Study Design: 29 patients (18 women, 11 men, median age 58.7 years, all white) with FGFR2 gene positive fusion iCCA were enrolled and treated with derazantinib (dose range 300-400mg QD) at eight sites in the United States and Italy between August 2014 and October 2017 as part of clinical trial ARQ 087-101 [NCT01752920]. Patients' plasma samples were collected (on Day 1, 8, 15, 22 of Cycle 1 and Day 1 of Cycles 2-6) and analyzed for levels of FGF & phosphate. FGF levels were quantified using commercially available ELISA kits for FGF-19 and 21 (R&D Systems, Minneapolis, MN), and FGF-23 (EMD-Millipore, Billerica, MA). Results: Preliminary data analysis showed clear increase in mean FGF19, 23, and phosphate levels in iCCa patients treated with derazantinib. On Cycle 2 Day 1, phosphate levels on average increased by 40% over baseline. FGF19 and FGF23 increased by 300% and 140%, respectively. Final results and any additional findings will be presented at the meeting. Conclusions: The changes in FGF19, FGF23, and phosphate observed during treatment suggest that at the recommended phase II dose of derazantinib (300 mg QD), clinical signs of target engagement are detectable. Additional data to demonstrate potential correlation between FGFs/phosphate levels and clinical outcomes, including response and toxicity will be presented. DeLIVERr, a pivotal study of derazantinib in patients with FGFR2 gene fusion positive iCCA is ongoing (NCT03230318). Citation Format: Terence Hall, Vincenzo Mazzaferro, Bassel El-Rayes, Christian Cotsoglou, William P. Harris, Nevana Damjanov, Gianluca Masi, Lorenza Rimassa, Nicola Personeni, Vittorina Zagonel, Kyriakos P. Papadopoulos, Sherrie Bhoori, Michele Droz-Dit-Busset, Walid Shaib, Maria Lamar, Julia Kazakin, Brian Schwartz, Yunxia Wang, Ronald E. Savage. Derazantinib (ARQ 087) pharmacodynamics: Alterations in FGF19/21/23 and phosphate in patients with cholangiocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-232.

ARQ 087 is an orally administered pan-FGFR inhibitor with multi-kinase activity. This Phase 1 study evaluated safety, pharmacokinetics, and pharmacodynamics of ARQ 087 and defined the recommended Phase 2 dose (RP2D). Patients with advanced solid tumours received ARQ 087 administered initially at 25 mg every other day and dose-escalated from 25 to 425 mg daily (QD) continuous dosing. FGF19, 21, 23, and serum phosphate were assessed as potential biomarkers of target engagement. 80 patients were enrolled, 61 in dose-escalation/food-effect cohorts and 19 with pre-defined tumour types in the expansion cohort. The most common ARQ 087-related adverse events were fatigue (49%), nausea (46%), aspartate aminotransferase (AST) increase (30%), and diarrhoea (23%). Four patients (5%) experienced grade 1 treatment-related hyperphosphataemia. Dose-limiting toxicity was reversible grade 3 AST increase. The RP2D was 300 mg QD. Pharmacokinetics were linear and dose-proportional from 25 to 325 mg QD, and were unaffected by food. Statistically significant changes (P-value<0.05) suggest phosphate and FGF19 levels as markers of target engagement. In 18 evaluable patients with FGFR genetic alterations, 3 confirmed partial responses (two intrahepatic cholangiocarcinomas (iCCA) with FGFR2 fusions and one urothelial cancer with FGFR2 and FGF19 amplification) and two durable stable disease at ⩾16 weeks with tumour reduction (FGFR2 fusion-positive iCCA and adrenocortical carcinoma with FGFR1 amplification) were observed. ARQ 087 had manageable toxicity at the RP2D of 300 mg QD, showed pharmacodynamics effects, and achieved objective responses, notably in patients with FGFR2 genetic alterations.

2524 Background: ARQ 092 is an oral, potent AKT inhibitor with single agent antitumor activity. P or P+C is the standard therapy or the therapy of choice for pts with various solid tumors. ARQ 092 potentiated antitumor activity of P in in vivo xenograft models, providing the rationale for this study. Methods: This is an open-label, phase Ib study of ARQ 092+C+P (CP Arm) or ARQ 092+P (P Arm) in pts with advanced solid tumors to determine safety and tolerability of these 2 combinations. Blood samples are collected for PK. Results: Enrollment into CP Arm has been completed with 13 pts (15% male; median age 62 years, 4 ovarian, 9 others) being treated in 2 dose cohorts (see table and results below). Enrollment into P Arm is ongoing. Data from P Arm (80 mg/m2 weekly) will be presented during the meeting. In CP Arm, 3 DLTs were observed in 2 pts (both received ARQ 092 at 200 mg BID, 1 day/week) including grade (G) 4 neutrophil count decreased, G 4 thrombocytopenia and G 3 diarrhea. ARQ 092-related adverse events (AEs) in ≥10% pts included diarrhea 69%, fatigue 54%, hyperglycemia 31%, maculopapular rash 31%, nausea 23%, mucosal inflammation 23%, anemia 15%, platelet count decreased 15% and hypokalemia 15%. Paclitaxel- and/or carboplatin-related AEs in ≥10% pts included fatigue 77%, alopecia 62%, thrombocytopenia 39%, platelet count decreased 39%, nausea 31%, lymphocyte count decreased 31%, neutrophil count decreased 31%, white blood cell count decreased 31%, anemia 23%, mucosal inflammation 23%, hypomagnesaemia 23%, peripheral sensory neuropathy 23%, neutropenia 15%, vomiting 15% and hypokalemia 15%. Two ovarian pts previously treated with CP achieved complete response (mutant AKT) and partial response (AKT mutation unknown) respectively and 3 pts (Gastroesophageal, pancreatic, ovarian mixed mullerian) experienced stable diseases for >12 weeks. PK data will be presented during the meeting. Conclusions: Encouraging anticancer activity was demonstrated in heavily pretreated ovarian cancer pts, but full dose CP was not tolerated by most patients. Clinical trial information: NCT02476955. [Table: see text]

Abstract Dysregulation of the PI3K-AKT signaling pathway is associated with a number of cancers. AKT can be activated through activated receptor tyrosine kinases, gain-of-function mutations of PIK3CA, PTEN deficiency, and AKT amplification or activating mutations such as AKT1-E17K. We present here the preclinical characterization of ARQ 751, which has distinct physico-chemical properties compared to our first generation inhibitor, ARQ 092. ARQ 751 has IC50 values of 0.55 nM, 0.81 nM and 1.31 nM for AKT1, 2 and 3, respectively, and does not inhibit any other kinase (out of the 245 tested) by greater than 50% at 5 μM, nor does it inhibit AKT lacking the PH domain. ARQ 751 strongly binds to wild-type AKT1 and mutant AKT1-E17K with Kd of 1.2 nM and 8.6 nM, respectively, and suppresses pAKT(S473) in 293T cells transiently transfected with AKT1-E17K. Additionally, membrane translocation of both wild-type and AKT1-E17K is inhibited in NIH 3T3 cells transiently transfected with wild-type AKT1 or mutant AKT1-E17K. Tests on 240 cancer cell lines (Oncopanel) showed the best antiproliferative effects on esophageal (100%, 3/3), breast (87.5%, 14/16), and head and neck cancer cells (67%, 4/6), with GI50 values GI50 < 1 μM. Cancer cell lines with PIK3CA/PIK3R1 mutations (73%; 33/45) are more sensitive to ARQ 751 (GI50<1μM) compared to wild-type (42%, 74/175). Interestingly, among PIK3CA/PIK3R1 wild type cell lines, the PTEN mutant (55%, 11/20) exhibited a similar sensitivity to PTEN wild-type cell lines (48%, 95/197). Of 17 tested breast cancer cell lines, all 8 with PIK3CA mutations are sensitive to ARQ 751. An in vivo efficacy study in AN3CA endometrial cancer xenograft model shows that ARQ 751 inhibits tumor growth (by up to 92% at the well tolerated continuous daily dose of 120 mg/kg) in a dose-dependent manner. Additionally, ARQ 751 exerted dose-dependent anti-tumor activity (by up to 98% at the 5 days on, 2 days off dose of 75mg/kg) in an AKT1-E17K mutant endometrial patient-derived xenograft (PDX) model. ARQ 751 causes significant pathway inhibition in vitro (at the concentrations of 3 nM on pAKT[S473] and 70 nM on pPRAS40 [T246]) and in vivo (on both pAKT[S473] and pPRAS40[T246] after 6 hours of dosing as low as 10 mg/kg) using AN3CA models. Pharmacokinetic data from repeat doses of ARQ 751 show a plasma half-life of 4 to 5 hours and no tissue accumulation. In conclusion, ARQ 751 is a potent and selective allosteric AKT inhibitor. PIK3CA/PIK3R1 and AKT mutations but not PTEN may predict ARQ 751 sensitivity. Our analysis suggests that endometrial, breast, esophageal, and head and neck cancers may represent viable indications for ARQ 751. Both PIK3CA/PIK3R1 and AKT1 mutations could be predictive biomarkers for patient selection, regardless of tumor type. Citation Format: Yi Yu, Ronald E. Savage, Sudharshan Eathiraj, Terence Hall, Brian Schwartz, Giovanni Abbadessa. In vitro and in vivo anti-tumor activity of ARQ 751, a potent and selective AKT inhibitor. [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 374.

The work in this paper describes the optimization of the 3-(3-phenyl-3H-imidazo[4,5-b]pyridin-2-yl)pyridin-2-amine chemical series as potent, selective allosteric inhibitors of AKT kinases, leading to the discovery of ARQ 092 (21a). The cocrystal structure of compound 21a bound to full-length AKT1 confirmed the allosteric mode of inhibition of this chemical class and the role of the cyclobutylamine moiety. Compound 21a demonstrated high enzymatic potency against AKT1, AKT2, and AKT3, as well as potent cellular inhibition of AKT activation and the phosphorylation of the downstream target PRAS40. Compound 21a also served as a potent inhibitor of the AKT1-E17K mutant protein and inhibited tumor growth in a human xenograft mouse model of endometrial adenocarcinoma.

Dysregulation of Fibroblast Growth Factor Receptor (FGFR) signaling through amplifications, mutations, and gene fusions has been implicated in a broad array of cancers (e.g. liver, gastric, ovarian, endometrial, and bladder). ARQ 087 is a novel, ATP competitive, small molecule, multi-kinase inhibitor with potent in vitro and in vivo activity against FGFR addicted cell lines and tumors. Biochemically, ARQ 087 exhibited IC50 values of 1.8 nM for FGFR2, and 4.5 nM for FGFR1 and 3. In cells, inhibition of FGFR2 auto-phosphorylation and other proteins downstream in the FGFR pathway (FRS2α, AKT, ERK) was evident by the response to ARQ 087 treatment. Cell proliferation studies demonstrated ARQ 087 has anti-proliferative activity in cell lines driven by FGFR dysregulation, including amplifications, fusions, and mutations. Cell cycle studies in cell lines with high levels of FGFR2 protein showed a positive relationship between ARQ 087 induced G1 cell cycle arrest and subsequent induction of apoptosis. In addition, ARQ 087 was effective at inhibiting tumor growth in vivo in FGFR2 altered, SNU-16 and NCI-H716, xenograft tumor models with gene amplifications and fusions. ARQ 087 is currently being studied in a phase 1/2 clinical trial that includes a sub cohort for intrahepatic cholangiocarcinoma patients with confirmed FGFR2 gene fusions (NCT01752920).