Aimee Bence Lin

Phase I Study of LY2606368, a Checkpoint Kinase 1 Inhibitor, in Patients With Advanced Cancer

PURPOSE The primary objective was to determine safety, toxicity, and a recommended phase II dose regimen of LY2606368, an inhibitor of checkpoint kinase 1, as monotherapy. PATIENTS AND METHODS This phase I, nonrandomized, open-label, dose-escalation trial used a 3 + 3 dose-escalation scheme and included patients with advanced solid tumors. Intravenous LY2606368 was dose escalated from 10 to 50 mg/m(2) on schedule 1 (days 1 to 3 every 14 days) or from 40 to 130 mg/m(2) on schedule 2 (day 1 every 14 days). Safety measures and pharmacokinetics were assessed, and pharmacodynamics were measured in blood, hair follicles, and circulating tumor cells. RESULTS Forty-five patients were treated; seven experienced dose-limiting toxicities (all hematologic). The maximum-tolerated doses (MTDs) were 40 mg/m(2) (schedule 1) and 105 mg/m(2) (schedule 2). The most common related grade 3 or 4 treatment-emergent adverse events were neutropenia, leukopenia, anemia, thrombocytopenia, and fatigue. Grade 4 neutropenia occurred in 73.3% of patients and was transient (typically < 5 days). Febrile neutropenia incidence was low (7%). The LY2606368 exposure over the first 72 hours (area under the curve from 0 to 72 hours) at the MTD for each schedule coincided with the exposure in mouse xenografts that resulted in maximal tumor responses. Minor intra- and intercycle accumulation of LY2606368 was observed at the MTDs for both schedules. Two patients (4.4%) had a partial response; one had squamous cell carcinoma (SCC) of the anus and one had SCC of the head and neck. Fifteen patients (33.3%) had a best overall response of stable disease (range, 1.2 to 6.7 months), six of whom had SCC. CONCLUSION An LY2606368 dose of 105 mg/m(2) once every 14 days is being evaluated as the recommended phase II dose in dose-expansion cohorts for patients with SCC.

Phase I study of LY2603618, a CHK1 inhibitor, in combination with gemcitabine in Japanese patients with solid tumors.

This phase I trial evaluated LY2603618, a selective inhibitor of the DNA damage checkpoint kinase 1, in combination with gemcitabine. Japanese patients with advanced solid tumors were enrolled. All patients received gemcitabine (1000 mg/m2 on days 1, 8, and 15 every 28 days) and either 170 mg (cohort 1) or 230 mg (cohort 2) of LY2603618. The primary objective was assessment of safety/tolerability. Pharmacokinetic/pharmacodynamic marker profiles were secondary objectives. Of the 17 patients enrolled, dose-limiting toxicities were observed in one patient in cohort 1 (n=7) and in two patients in cohort 2 (n=10). The most common grade 3 or more drug-related treatment-emergent adverse events were hematological. Three patients discontinued because of adverse events. Dose-dependent decreases in LY2603618 exposure were observed, but the LY2603618 pharmacokinetics at each dose were consistent within and between cycles and did not influence gemcitabine pharmacokinetics. Circulating plasma DNA decreased from baseline in all four patients who achieved a partial response. Administration of 170 or 230 mg of LY2603618 following a standard dose of gemcitabine showed acceptable safety and tolerability in Japanese patients with solid tumors.

The Checkpoint Kinase 1 Inhibitor Prexasertib Induces Regression of Preclinical Models of Human Neuroblastoma

Purpose: Checkpoint kinase 1 (CHK1) is a key regulator of the DNA damage response and a mediator of replication stress through modulation of replication fork licensing and activation of S and G2–M cell-cycle checkpoints. We evaluated prexasertib (LY2606368), a small-molecule CHK1 inhibitor currently in clinical testing, in multiple preclinical models of pediatric cancer. Following an initial assessment of prexasertib activity, this study focused on the preclinical models of neuroblastoma. Experimental Design: We evaluated the antiproliferative activity of prexasertib in a panel of cancer cell lines; neuroblastoma cell lines were among the most sensitive. Subsequent Western blot and immunofluorescence analyses measured DNA damage and DNA repair protein activation. Prexasertib was investigated in several cell line–derived xenograft mouse models of neuroblastoma. Results: Within 24 hours, single-agent prexasertib promoted γH2AX–positive double-strand DNA breaks and phosphorylation of DNA damage sensors ATM and DNA–PKcs, leading to neuroblastoma cell death. Knockdown of CHK1 and/or CHK2 by siRNA verified that the double-strand DNA breaks and cell death elicited by prexasertib were due to specific CHK1 inhibition. Neuroblastoma xenografts rapidly regressed following prexasertib administration, independent of starting tumor volume. Decreased Ki67 and increased immunostaining of endothelial and pericyte markers were observed in xenografts after only 6 days of exposure to prexasertib, potentially indicating a swift reduction in tumor volume and/or a direct effect on tumor vasculature. Conclusions: Overall, these data demonstrate that prexasertib is a specific inhibitor of CHK1 in neuroblastoma and leads to DNA damage and cell death in preclinical models of this devastating pediatric malignancy. Clin Cancer Res; 23(15); 4354–63. ©2017 AACR.

Achieving Precision Death with Cell-Cycle Inhibitors that Target DNA Replication and Repair

All cancers are characterized by defects in the systems that ensure strict control of the cell cycle in normal tissues. The consequent excess tissue growth can be countered by drugs that halt cell division, and, indeed, the majority of chemotherapeutics developed during the last century work by disrupting processes essential for the cell cycle, particularly DNA synthesis, DNA replication, and chromatid segregation. In certain contexts, the efficacy of these classes of drugs can be impressive, but because they indiscriminately block the cell cycle of all actively dividing cells, their side effects severely constrain the dose and duration with which they can be administered, allowing both normal and malignant cells to escape complete growth arrest. Recent progress in understanding how cancers lose control of the cell cycle, coupled with comprehensive genomic profiling of human tumor biopsies, has shown that many cancers have mutations affecting various regulators and checkpoints that impinge on the core cell-cycle machinery. These defects introduce unique vulnerabilities that can be exploited by a next generation of drugs that promise improved therapeutic windows in patients whose tumors bear particular genomic aberrations, permitting increased dose intensity and efficacy. These developments, coupled with the success of new drugs targeting cell-cycle regulators, have led to a resurgence of interest in cell-cycle inhibitors. This review in particular focuses on the newer strategies that may facilitate better therapeutic targeting of drugs that inhibit the various components that safeguard the fidelity of the fundamental processes of DNA replication and repair. Clin Cancer Res; 23(13); 3232–40. ©2017 AACR.

A randomized, phase 2 evaluation of the CHK1 inhibitor, LY2603618, administered in combination with pemetrexed and cisplatin in patients with advanced nonsquamous non‐small cell lung cancer

This phase 2 portion of a phase 1/2 study examined the efficacy and safety of LY2603618, a selective checkpoint kinase 1 inhibitor, combined with pemetrexed and cisplatin (LY+Pem+Cis) in patients with advanced nonsquamous non-small cell lung cancer (NSCLC). This multicenter, randomized, controlled, open-label study (NCT01139775) enrolled patients with stage IV nonsquamous NSCLC and an Eastern Cooperative Oncology Group performance status ≤1. Patients were randomized (2:1) to LY+Pem+Cis or pemetrexed and cisplatin (Pem+Cis). Induction therapy comprised four 21-day cycles of 500 mg/m2 pemetrexed and 75mg/m2 cisplatin on Day 1 (both arms) and 275mg LY2603618 on Day 2 (LY+Pem+Cis arm). Maintenance therapy comprised 500mg/m2 pemetrexed on Day 1 (both arms) and 275mg LY2603618 on Day 2 (LY+Pem+Cis arm) until disease progression. The primary endpoint was progression-free survival (PFS). Enrollment was permanently halted before target enrollment was met due to a greater number of thromboembolic events in the LY+Pem+Cis arm. Sixty-two patients were enrolled (LY+Pem+Cis, n=39; Pem+Cis, n=23). Bayesian and frequentist analysis demonstrated superior PFS in the LY+Pem+Cis arm vs the Pem+Cis arm (median [90% confidence interval]: LY+Pem+Cis, 4.7 months [4.-7.1]; Pem+Cis, 1.5 months [1.3-2.9]; P=0.022). Seven patients in the LY+Pem+Cis arm (vs 0 in the Pem+Cis arm) experienced serious thromboembolic events: pulmonary embolism (n=5), ischemic stroke (n=1), and cerebrovascular accident (n=1). Although the primary endpoint was met, the combination of LY2603618+Pem+Cis will not be further developed for treating advanced nonsquamous NSCLC due to the potential increased risk of thromboembolic events with this combination. ClinicalTrials.gov Identifier: NCT01139775.

Evaluation of prexasertib, a checkpoint kinase 1 inhibitor, in a phase ib study of patients with squamous cell carcinoma

Purpose: Prexasertib, a checkpoint kinase 1 inhibitor, demonstrated single-agent activity in patients with advanced squamous cell carcinoma (SCC) in the dose-escalation portion of a phase I study (NCT01115790). Monotherapy prexasertib was further evaluated in patients with advanced SCC. Patients and Methods: Patients were given prexasertib 105 mg/m2 as a 1-hour infusion on day 1 of a 14-day cycle. Expansion cohorts were defined by tumor and treatment line. Safety, tolerability, efficacy, and exploratory biomarkers were analyzed. Results: Prexasertib was given to 101 patients, including 26 with SCC of the anus, 57 with SCC of the head and neck (SCCHN), and 16 with squamous cell non–small cell lung cancer (sqNSCLC). Patients were heavily pretreated (49% ≥3 prior regimens). The most common treatment-related adverse event was grade 4 neutropenia (71%); 12% of patients had febrile neutropenia. Median progression-free survival was 2.8 months [90% confidence interval (CI), 1.9–4.2] for SCC of the anus, 1.6 months (90% CI, 1.4–2.8) for SCCHN, and 3.0 months (90% CI, 1.4–3.9) for sqNSCLC. The clinical benefit rate at 3 months (complete response + partial response + stable disease) across tumors was 29% (23% SCC of the anus, 28% SCCHN, 44% sqNSCLC). Four patients with SCC of the anus had partial or complete response [overall response rate (ORR) = 15%], and three patients with SCCHN had partial response (ORR = 5%). Biomarker analyses focused on genes that altered DNA damage response or increased replication stress. Conclusions: Prexasertib demonstrated an acceptable safety profile and single-agent activity in patients with advanced SCC. The prexasertib maximum-tolerated dose of 105 mg/m2 was confirmed as the recommended phase II dose. Clin Cancer Res; 24(14); 3263–72. ©2018 AACR.

Treatment patterns and health care resource use in patients receiving multiple lines of therapy for metastatic squamous cell carcinoma of the head and neck in the United Kingdom

Abstract This study evaluated the patterns of care and health care resource use (HCRU) in patients with metastatic squamous cell carcinoma of the head and neck (SCCHN) who received ≥3 lines of systemic therapy in the United Kingdom (UK). Oncologists (n = 40) abstracted medical records for patients with metastatic SCCHN who initiated third‐line systemic therapy during 1 January 2011–30 August 2014 (n = 220). Patient characteristics, treatment patterns and SCCHN‐related HCRU were summarised descriptively for the metastatic period; exploratory multivariable regression analyses were conducted on select HCRU outcomes. At metastatic diagnosis, most patients had an Eastern Cooperative Oncology Group performance status (PS) of 0/1 (95%). For patients with PS 0/1, the most common first‐line treatment was cisplatin+5‐fluorouracil (5‐FU); docetaxel was the most common second‐ and third‐line treatment. For patients with PS ≥ 2, the most common first‐, second‐, and third‐line treatments were carboplatin+5‐FU, cetuximab, and methotrexate, respectively. Most patients received supportive care during (85%) and after (89%) therapy. This study provides useful information, prior to the availability of immunotherapy, on patient characteristics, treatment patterns, HCRU, and survival in a real‐world UK population with metastatic SCCHN receiving ≥3 lines of systemic therapy. Patterns of care and HCRU varied among patients with metastatic SCCHN; specific systemic therapies varied by patient PS.

Correction to: A phase I study of LY3164530, a bispecific antibody targeting MET and EGFR, in patients with advanced or metastatic cancer

The original version of this article unfortunately contained a mistake. The co-authors’ names were incorrect.

Abstract 1778: A clinical genomic biomarker study of the CHK1 inhibitor prexasertib in advanced head and neck squamous cancer and squamous cell carcinoma of the anus

CHK1 plays a critical role in DNA damage repair (DDR) pathways as well as in coordinating DNA replication. Selective CHK1/CHK2 compounds are being tested in clinical trials but predictive biomarkers of patient response are lacking. A phase 1b expansion cohort study (I4D-MC-JTJA, NCT01115790) with the CHK 1 inhibitor, prexasertib, included patients with advanced, metastatic head and neck squamous cell carcinoma (HNSCC) or squamous cell carcinoma of the anus (SCCA). To identify genomic biomarkers associated with single-agent drug response, pre-treatment tissues (archived or biopsy) from 71 consented patients (HNSCC=47, SCCA=24) were subjected to next-generation sequencing (NGS) using the FoundationOne gene panel. In this subset of patients, the disease control rate (DCR) (Complete Response (CR) + Partial Response (PR) + Stable Disease (SD) based on RECIST Criteria (v 1.1)) was 60% (28/47) and 75% (18/24), respectively. We present here the observed genetic alterations corresponding to three pathways, Cell Cycle, DNA Damage Repair (DDR) and PI3K. In addition, patients’ human papillomavirus (HPV) carrier status was inferred from DNA sequencing using HPV-specific capture probes. HPV+ was 47% for HNSCC and 87% for SCCA. HPV+ and TP53 mutations were mutually exclusive across the two patient cohorts. In HNSCC patients with evaluable progression-free survival (PFS) data, greater clinical efficacy was observed in the HPV+ cohort (median PFS: 4.5 vs 1.4 months, log-rank p = 0.0008). Known or likely loss-of-function (LOF) mutations in FBXW7 and PARK2, two genes implicated in Cyclin E1 proteolysis, were noted in patients with favorable response in both tumor types. Across both HNSCC and SCCA cohorts, mutations and/or germline variants in the DDR genes BRCA1, BRCA2, MRE11A and ATR but not in Fanconi (FANC) pathway genes, were found in patients with treatment benefit. Whereas PIK3CA mutations were infrequent in the HNSCC cohort, in SCCA, mutations occurred in 5/8 (63%) patients with disease control vs 1/6 (17%) with PD. All 7 PI3KCA mutations observed in HPV+ HNSCC and SCCA patients mapped to the helical domain suggestive of Apobec-induced mutagenesis as their source of origin. The enhanced clinical benefit to prexasertib associated with HPV+ in HNSCC may reflect a prognostic effect. Alternatively, the clinical biomarker findings may support the hypothesis that oncogene-induced replication stress (RS) (i.e. arising from HPV E6/E7 and/or FBXW7 loss-dependent Cyclin E1 dysregulation) in the context of attenuated DDR (i.e. BRCA1/2, MRE11A mutations) may sensitize patients to prexasertib monotherapy. Citation Format: Ricardo Martinez, Sameera R. Wijayawardana, David Hong, Johanna Bendell, Anna Maria Russell, Richard P. Beckmann, Aimee Bence Lin. A clinical genomic biomarker study of the CHK1 inhibitor prexasertib in advanced head and neck squamous cancer and squamous cell carcinoma of the anus [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1778. doi:10.1158/1538-7445.AM2017-1778

Abstract CT240: Checkpoint kinase (CHK) 1/2 inhibitor LY2606368 in a phase I dose-expansion study in patients with squamous cell carcinoma of the head and neck

Background: LY2606368 is a CHK1/2 inhibitor. In addition to its role in DNA damage response, CHK1 also phosphorylates multiple downstream targets that regulate DNA replication, chromosome alignment, spindle checkpoints, and exit from cytokinesis. Since potent inhibition of CHK1 is predicted to generate DNA damage and mitotic catastrophe, LY2606368 was evaluated as a single agent in expansion cohorts of patients with recurrent/metastatic squamous cell carcinoma of the head and neck (SCCHN). Methods: This was a phase I, multicenter, nonrandomized, open-label study in patients with advanced cancer (NCT01115790). Based on results from the dose-escalation phase, dose-expansion cohorts were comprised of patients with SCC given LY2606368 at the maximum tolerated dose (MTD) of 105 mg/m 2 on day 1 of a 14-day schedule. Cohorts were defined by tumor location and by line of treatment. Patients were assessed for safety, tolerability, and preliminary efficacy. Pretreatment biopsies were obtained for pharmacogenomic analysis, including human papillomavirus (HPV) status. Aggregate results from patients with recurrent/metastatic SCCHN are presented. Results: Fifty-seven patients with recurrent/metastatic SCCHN were enrolled in the dose-expansion phase. Over 50% of patients had received ≥2 prior lines of treatment (median of 3 cycles; range: 1 to 5) in the recurrent/metastatic setting. The most frequently reported adverse event (AE) was a transient (typically 10% of patients included thrombocytopenia (44%), anemia (25%), fatigue (23%), and headache (14%). The majority of non-hematologic AEs were grade 1 or 2 (per Common Terminology Criteria) in severity. Three patients (5%) had a partial response and 25 patients (44%) had stable disease for at least 3 cycles. The duration of response ranged from 4.8-7.8+ months, and the median progression-free survival (PFS) was 1.6 months (90% confidence interval: 1.4, 2.8). Biopsy samples were evaluable from 34 patients. The median PFS by HPV status was 4.5 months in 15 patients who were HPV positive, and 1.4 months in 19 patients who were HPV negative (log-rank test, p = .0012). Conclusions: LY2606368 has an acceptable safety profile and demonstrates modest preliminary activity in a subset of patients with recurrent/metastatic SCCHN. The MTD of 105 mg/m 2 is confirmed as the recommended dose for phase II testing. Citation Format: Johanna Bendell, Stefan Grant, Filip Janku, Jeffrey Infante, William N. William, Todd M. Bauer, Sarina Piha-Paul, Ricardo Martinez, Sameera Wijayawardana, Ji Lin, Lisa Golden, Aimee Bence Lin, David Hong. Checkpoint kinase (CHK) 1/2 inhibitor LY2606368 in a phase I dose-expansion study in patients with squamous cell carcinoma of the head and neck. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr CT240. doi:10.1158/1538-7445.AM2015-CT240