Spectrum Selective Kinase Inhibitor Research Articles

Abstract 514: Salt-inducible kinase inhibitor OMX-0407 drives cell-cycle arrest in vitro and in vivo: An in-depth MoA analysis by phospho-proteomics

Abstract Based on iOmx’ proprietary iOTargTM genetic screening platform, salt-inducible kinase (SIK) 3 was identified as a novel cell signaling modulator in cancer biology. OMX-0407, an orally available, spectrum-selective kinase inhibitor targets several members of the SIK family and is known to prevent tumor-promoting function of the SIK-family through repolarization of the tumor microenvironment by enhancing caspase-mediated apoptosis upon death-receptor signaling. In addition, OMX-0407 inhibits individual key members of the tyrosine and tyrosine-like kinase family that are involved in cancer cell proliferation and cell cycle regulation. Via this dual mode of action, OMX-0407 has the potential to effectively fight solid tumors as exemplified by its striking single-agent efficacy in multiple pre-clinical tumor models. A comprehensive anti-tumor viability screen of >200 human cancer cell lines revealed striking effects of OMX-0407 on cancer cell viability across various cancer indications, resulting in a distinct sensitivity profile across various tumor indications with particularly strong effects on renal cell carcinoma (RCC) and squamous non-small cell lung cancer (sqNSCLC). Phospho-proteomics screening demonstrated pharmacodynamic activity of OMX-0407 in sensitive tumor cell lines via inhibition of key cellular processes such as cell motility, proliferation, and cell cycle regulation across different indications. Orthogonal functional in vitro assays confirmed the association of the OMX-0407-mediated anti-tumor efficacy with the arrest of G1/S transition and corresponding downregulation of cell cycle associated proteins PAK1/2 and ARHGAP35. The profound impact of OMX-0407 on fundamental regulatory mechanisms of cell division and cancer cell apoptosis translates into dose-dependent single-agent, anti-tumor efficacy in various pre-clinical tumor models of selected indications. Combination with Axitinib, a selective orally available inhibitor of vascular endothelial growth factor receptor 2, significantly enhanced anti-tumor efficacy and pharmacodynamic inhibition of cell growth as well as angiogenesis. These data further strengthen the potential of OMX-0407 in the treatment of RCC as well as other indications. In summary, OMX-0407 is a novel spectrum selective kinase inhibitor, currently under evaluation in a clinical Phase I trial (NCT05826600). OMX-0407 demonstrates strong anti-tumor efficacy in monotherapy in selected sensitive indications through a dual-pronged MoA, by modulating the tumor microenvironment and exerting direct anti-tumor activity in solid tumor indications with high unmet medical need. Citation Format: Ilona-Petra Maser, Marisa Stebegg-Wagner, Bettina Bauer, Filippos Konstantinidis, Andreas Schirmer, Moritz Zulley, Sonja Lacher, Barbara Kracher, Parastou Kohvaei, Murray Yule, Hannes Loferer, Stefan Bissinger. Salt-inducible kinase inhibitor OMX-0407 drives cell-cycle arrest in vitro and in vivo: An in-depth MoA analysis by phospho-proteomics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 514.

A phase I study with exploratory pharmacodynamic endpoints of XL647, a novel spectrum selective kinase inhibitor, administered orally daily to patients (pts) with advanced solid malignancies

14044 Background: XL647 is an orally bioavailable small molecule inhibitor of multiple receptor tyrosine kinases involved in tumorigenesis, angiogenesis, and metastasis, including EGFR/ErbB1, ErbB2/HER2, VEGFR2/KDR, and EphB4. In a previous Phase I study, the MTD was 350 mg when XL647 was dosed orally for 5 consecutive days every 14 days. Of 41 pts treated, one pt with NSCLC achieved a PR and 14 pts had prolonged stable disease (3.5–14+ months). The purpose of the present study is to determine the MTD of XL647 administered orally on a continuous daily schedule. Methods: Pts are enrolled in successive cohorts to receive XL647 daily for repeated 28 day cycles. PK sampling is performed to determine Cmax, and AUC at each dose level. Plasma samples are analyzed by ELISA for mechanism-of-action related molecules. Eyebrow hair bulbs are being evaluated by IHC to monitor effects of XL647 on signal transduction pathways downstream of EGFR. Tumor response is assessed every 8 weeks by RECIST. Pts remain on study until PD or unacceptable AEs. Results: Twelve pts have been enrolled. The starting dose was 75 mg (n=3) and has been escalated to150 mg (n=3), 200 mg (n=3) and 300 mg (n=3). To date, dose escalation continues as no DLTs have occurred and the MTD has not been determined. Ten pts remain on study, including 4 with stable disease for at least 3 months. In cohort 2, eyebrow samples from 3 pts were analyzed. XL647 caused a significant reduction in the phosphorylation of the EGFR downstream signaling kinases AKT (up to 73%) and ERK (up to 78%) in 2/3 and 3/3 pts, respectively. Preliminary analysis of potential plasma protein biomarkers from pts in cohorts 1 and 2 showed a trend towards upregulation of PlGF plasma levels in 4/6 pts during XL647 treatment. Conclusions: XL647 is well-tolerated when administered daily at doses tested to date. Dose escalation will continue until the MTD is defined. Analysis of eyebrow samples demonstrated its feasibility as a potential surrogate epidermal tissue for assessing inhibition of EGFR downstream targets by XL647. Updated safety, PK and pharmacodynamic results will be presented. [Table: see text]

Inhibition of the T790M Gatekeeper Mutant of the Epidermal Growth Factor Receptor by EXEL-7647

Agents inhibiting the epidermal growth factor receptor (EGFR) have shown clinical benefit in a subset of non-small cell lung cancer patients expressing amplified or mutationally activated EGFR. However, responsive patients can relapse as a result of selection for EGFR gene mutations that confer resistance to ATP competitive EGFR inhibitors, such as erlotinib and gefitinib. We describe here the activity of EXEL-7647 (XL647), a novel spectrum-selective kinase inhibitor with potent activity against the EGF and vascular endothelial growth factor receptor tyrosine kinase families, against both wild-type (WT) and mutant EGFR in vitro and in vivo. The activity of EGFR inhibitors against WT and mutant EGFRs and their effect on downstream signal transduction was examined in cellular assays and in vivo using A431 and MDA-MB-231 (WT EGFR) and H1975 (L858R and T790M mutant EGFR) xenograft tumors. EXEL-7647 shows potent and long-lived inhibition of the WT EGFR in vivo. In addition, EXEL-7647 inhibits cellular proliferation and EGFR pathway activation in the erlotinib-resistant H1975 cell line that harbors a double mutation (L858R and T790M) in the EGFR gene. In vivo efficacy studies show that EXEL-7647 substantially inhibited the growth of H1975 xenograft tumors and reduced both tumor EGFR signaling and tumor vessel density. Additionally, EXEL-7647, in contrast to erlotinib, substantially inhibited the growth and vascularization of MDA-MB-231 xenografts, a model which is more reliant on signaling through vascular endothelial growth factor receptors. These studies provide a preclinical basis for clinical trials of XL647 in solid tumors and in patients bearing tumors that are resistant to existing EGFR-targeted therapies.

342 POSTER A phase I dose-escalation and pharmacokinetic (PK) study of XL647, a novel spectrum selective kinase inhibitor, administered orally to patients with advanced solid malignancies (ASM)

342 POSTER A phase I dose-escalation and pharmacokinetic (PK) study of XL647, a novel spectrum selective kinase inhibitor, administered orally to patients with advanced solid malignancies (ASM)

404 POSTER Pharmacodynamics (pd) of x1880, a novel spectrum selective kinase inhibitor (SSKI), administered orally to patients (pts) with advanced solid tumors (AST)

404 POSTER Pharmacodynamics (pd) of x1880, a novel spectrum selective kinase inhibitor (SSKI), administered orally to patients (pts) with advanced solid tumors (AST)

97 POSTER A phase I dose-escalation study of the safety and pharmacokinetics of a novel spectrum selective kinase inhibitor, XL820, administered orally to patients with solid tumors

KINASE INHIBITOR, XL820, ADMINISTERED ORALLY TO PATIENTS WITH SOLID TUMORS Kyriakos P. Papadopoulos, Jordi Rodon, Alain Mita, Patricia O’Rourke, Amita Patnaik, Eric Rubin, Anthony W. Tolcher, Mark Stein 2 Institute for Drug Development, Cancer Therapy and Research Center, San Antonio, Texas, USA; Cancer Institute of New Jersey, Robert Wood Johnson University Hospital, New Brunswick, New Jersey, USA

A phase I study examining weekly dosing and pharmacokinetics (PK) of a novel spectrum selective kinase inhibitor, XL999, in patients (pts) with advanced solid malignancies (ASM)

13024 Background: XL999 is a small molecule inhibitor of multiple kinases involved in tumor cell growth, angiogenesis, and metastasis, including VEGFR2 (KDR), PDGFRα/β, FGFR1/3, FLT-3, and SRC. A phase I study of XL999 administered as a 4 hr infusion every 2 weeks in pts with ASM showed that the maximum tolerated dose (MTD) was 3.2 mg/kg and the plasma t1/2 was approximately 24 hrs. Three pts dosed at 0.2–1.6 mg/kg (anaplastic thyroid cancer [1], renal cell carcinoma [1], hepatic squamous cell carcinoma [1]) had partial responses and 9 pts had stable disease for 3 to 11 months. Based on these data, a weekly (wkly) dosing schedule with PK monitoring was explored. Methods: XL999 at 3.2 mg/kg was administered to pts as a 4 hr infusion on day (d) 1 and 8 with toxicity assessment. Pts received further doses of XL999 wkly in the absence of unacceptable toxicity, disease progression, or accumulation based on PK results. Results: Overall 15 pts were enrolled and 7 were initially dosed at 3.2 mg/kg. Two of these pts experienced severe drug related toxicities, including 1 pt with G3 fatigue who was able to continue wkly XL999 at 2.4 mg/kg and another pt who was discontinued after developing reversible cardiac dysfunction on d1. The next 8 pts were treated at 2.4 mg/kg and none of these has experienced any G2 or worse drug related adverse events. One asymptomatic pt with non-specific ECG changes after d1 was discontinued from study. Four of 11 evaluable pts had SD. In 7 evaluable pts treated at the 2.4 dose level, the mean Cmax was 519 ng/mL with moderate interpatient variability (coefficient of variation, CV) of 38%. Intrapatient variability in the Cmax values on d1 and d15 was moderate (≤3-fold); however, there was no evidence of drug accumulation on repeat dosing. Conclusions: XL999 administered wkly as a 4 hr infusion at a dose of 2.4 mg/kg appears to be well tolerated with no evidence of drug accumulation. The safety and PK data suggest that 2.4 mg/kg on a wkly schedule is appropriate for phase 2 studies. [Table: see text]

A phase I study of a novel spectrum selective kinase inhibitor (SSKI), XL880, administered orally in patients (pts) with advanced solid tumors (STs)

3041 Background: XL880 is a sub-nM inhibitor of the hepatocyte growth factor receptor (Met) and vascular endothelial growth factor (VEGF) family receptor tyrosine kinase (RTK). PDGFRβ, KIT, FLT3, and Tie-2 are also inhibited at low nM concentrations in vitro. XL880 is the 1st orally bioavailable small molecule Met inhibitor to enter the clinic. Methods: Pts with advanced STs were enrolled in successive cohorts to receive XL880 orally as a single dose on Day (D) 1 with pharmacokinetic (PK) sampling, followed by 5 consecutive daily doses (DD) starting on D 4 with additional PK sampling. Pts then continued to receive XL880 for 5 consecutive days, repeated every 14 days. Results: Nineteen pts have been treated across 5 dose levels: 0.1, 0.2, 0.4, 0.8, and 1.6 mg/kg. No dose-limiting toxicities have been observed. Two pts have demonstrated grade 2 hypertension, at 0.8 and 1.6 mg/kg respectively. PK analysis indicated that systemic drug exposure (AUC) and peak plasma levels (Cmax) increased approximately dose-proportionally (r2 values = .89 and .87 respectively) with increasing XL880 dose (0.1–1.6 mg/kg). Following 5 consecutive DD, AUC values were 175–304% higher and Cmax values were 30–203% higher than following a single XL880 dose, suggesting possible drug accumulation with repeat dosing. Terminal half-life values were ∼60 hours (hrs) following 5 consecutive DD (D 8 range: 40–66 hrs), were more variable following a single dose (D 1 range: 26–87 hrs), and appeared to be unaffected by dose. A pt with papillary renal cell carcinoma has a partial response (DD = 0.2 mg/kg) and pts with carcinoid and melanoma have had minor responses. Conclusions: XL880 is a RTK inhibitor with a novel spectrum of activity that targets both tumor cells and tumor-associated vasculature. XL880 is well tolerated up to the 1.6 mg/kg dose, with continued dose escalation ongoing. XL880 demonstrates biologic activity through hypertension and antitumor activity. [Table: see text]

A phase I dose-escalation and pharmacokinetic (PK) study of a novel spectrum selective kinase inhibitor, XL647, in patients with advanced solid malignancies (ASM)

3044 Background: XL647 is an orally bioavailable small molecule inhibitor of multiple receptor tyrosine kinases involved in tumor cell growth, angiogenesis, and metastasis, including EGFR (erbB1), erbB2, VEGFR2/KDR, and EphB4. Methods: Patients (pts) with ASM were enrolled in successive cohorts to receive XL647 orally as a single dose on day 1 with PK sampling, followed by 5 continuous daily doses starting on day 4 with additional PK sampling. Pts then continued to receive XL647 for 5 consecutive days, followed by a break, with cycles repeating every 14 days. Tumor imaging was conducted at baseline, after the first 3 or 4 cycles, and then after every 4 cycles. Pts were allowed to stay on-study in the absence of unacceptable toxicity until evidence of disease progression. Results: A total of 37 pts have been treated across 9 dose levels to date: 0.06, 0.12, 0.19, 0.28, 0.39, 0.78, 1.56, 3.12, 4.68, and 7.0 mg/kg. One pt at 3.12 mg/kg had a dose limiting toxicity (DLT) of asymptomatic QTc prolongation on electrocardiogram, resulting in expansion of that cohort. The first two pts who received 7.0 mg/kg experienced DLTs of grade 3 diarrhea, requiring dose reduction. Both pts from the 7.0 mg/kg cohort tolerated 4.68 mg/kg well. Expansion of the 4.68 mg/kg cohort to 6 pts occurred without further DLTs and this is considered the maximum tolerated dose (MTD). One serious adverse event, grade 4 pulmonary embolism, was considered possibly related to study treatment in a pt dosed at 0.28 mg/kg. PK analysis indicates that XL647 shows approximately dose-proportional exposure, a mean time to maximal concentration (tmax) of 6–9 hours and an elimination half-life of 50–70 hours. To date, 1 pt (non-small cell lung cancer [NSCLC]) from cohort 1 had a partial response and 7 others (NSCLC [2], chordoma [2], adenoid cystic carcinoma, adrenocortical carcinoma, colorectal) have had prolonged stable disease (>3 months). Conclusions: XL647 has been well tolerated. An MTD of 4.68 mg/kg oral dosing for 5 consecutive days every 14 days has been established. Exploration of additional dosing schedules is ongoing, including continuous daily dosing. [Table: see text]

141 The spectrum-selective kinase inhibitor EXEL-0999 inhibits mitogenic and angiogenic kinases, and causes rapid tumor vasculature destruction and regression in mouse xenograft models

141 The spectrum-selective kinase inhibitor EXEL-0999 inhibits mitogenic and angiogenic kinases, and causes rapid tumor vasculature destruction and regression in mouse xenograft models