A Phase 2 study of prexasertib (LY2606368) in platinum resistant or refractory recurrent ovarian cancer.

OBJECTIVE: High-grade serous ovarian cancer, the most frequent type of ovarian cancer, has a poor prognosis and novel treatments are needed for patients with platinum resistant/refractory disease. New therapeutic strategies targeting cell cycle checkpoints, including CHK1 inhibition with prexasertib, may help improve clinical response and overcome resistance. METHODS: Patients with ovarian cancer (N = 169) were assigned to 4 cohorts as part of the Phase 2 multicenter trial (NCT03414047): Cohort 1: platinum resistant, BRCA-wildtype with ≥3 lines prior therapy; Cohort 2: platinum resistant BRCA-wildtype with <3 lines prior therapy; Cohort 3: platinum resistant, BRCA-mutated with prior PARP inhibitor therapy; Cohort 4: platinum refractory, BRCA-mutated, or BRCA-wildtype with any number of prior therapy lines. The primary endpoint was objective response rate (ORR) and secondary endpoints included disease control rate (DCR), and safety. DNA from tumor biopsies was sequenced to identify biomarkers. RESULTS: The ORR in platinum resistant patients (Cohorts 1--3) was 12.1%, and 6.9% in platinum refractory patients. In platinum resistant patients, DCR was 37.1%, and consistent across cohorts. In platinum refractory patients, DCR was 31.0%. Consistent with the prexasertib mechanism of action, the most common treatment related adverse events of all grades included thrombocytopenia, neutropenia, fatigue, nausea, and anemia. CONCLUSIONS: Prexasertib demonstrated durable single agent activity in a subset of patients with recurrent ovarian cancer regardless of clinical characteristics, BRCA status, or prior therapies, including PARPi. There was no obvious correlation with genomic alterations in responders vs non-responders, emphasizing the need for alternative biomarker approaches for responder identification.

Therapeutic high affinity T cell receptor targeting a KRASG12D cancer neoantigen.

Neoantigens derived from somatic mutations are specific to cancer cells and are ideal targets for cancer immunotherapy. KRAS is the most frequently mutated oncogene and drives the pathogenesis of several cancers. Here we show the identification and development of an affinity-enhanced T cell receptor (TCR) that recognizes a peptide derived from the most common KRAS mutant, KRASG12D, presented in the context of HLA-A*11:01. The affinity of the engineered TCR is increased by over one million-fold yet fully able to distinguish KRASG12D over KRASWT. While crystal structures reveal few discernible differences in TCR interactions with KRASWT versus KRASG12D, thermodynamic analysis and molecular dynamics simulations reveal that TCR specificity is driven by differences in indirect electrostatic interactions. The affinity enhanced TCR, fused to a humanized anti-CD3 scFv, enables selective killing of cancer cells expressing KRASG12D. Our work thus reveals a molecular mechanism that drives TCR selectivity and describes a soluble bispecific molecule with therapeutic potential against cancers harboring a common shared neoantigen.

A Phase 1b Trial of Prexasertib in Combination with Standard-of-Care Agents in Advanced or Metastatic Cancer.

BACKGROUND: The checkpoint kinase 1 (CHK1) inhibitor prexasertib exhibited modest monotherapy antitumor activity in prior trials, suggesting that combination with chemotherapy or other targeted agents may be needed to maximize efficacy. OBJECTIVES: The aim of this study was to determine the recommended phase II dose and schedule of prexasertib in combination with either cisplatin, cetuximab, pemetrexed, or 5-fluorouracil in patients with advanced and/or metastatic cancer, and to summarize preliminary antitumor activity of these combinations. PATIENTS AND METHODS: This phase Ib, nonrandomized, open-label study comprised dose-escalation phase(s) with multiple sub-arms evaluating different prexasertib-drug combinations: Part A, prexasertib + cisplatin (n = 63); Part B, prexasertib + cetuximab (n = 41); Part C, prexasertib + pemetrexed (n = 3); Part D, prexasertib + 5-fluorouracil (n =8). Alternate dose schedules/regimens intended to mitigate toxicity and maximize dose exposure and efficacy were also explored in sub-parts. RESULTS: In Part A, the maximum tolerated dose (MTD) of prexasertib in combination with cisplatin (75 mg/m2) was declared at 80 mg/m2, with cisplatin administered on Day 1 and prexasertib on Day 2 of a 21-day cycle. The overall objective response rate (ORR) in Part A was 12.7%, and 28 of 55 evaluable patients (50.9%) had a decrease in target lesions from baseline. The most frequent treatment-related adverse events (AEs) in Part A were hematologic, with the most common being white blood cell count decreased/neutrophil count decreased, experienced by 73.0% (any grade) and 66.7% (grade 3 or higher) of patients. In Part B, an MTD of 70 mg/m2 was established for prexasertib administered in combination with cetuximab (500 mg /m2), both administered on Day 1 of a 14-day cycle. The overall ORR in Part B was 4.9%, and 7 of 31 evaluable patients (22.6%) had decreased target lesions compared with baseline. White blood cell count decreased/neutrophil count decreased was also the most common treatment-related AE (56.1% any grade; 53.7% grade 3 or higher). In Parts A and B, hematologic toxicities, even with the addition of prophylactic granulocyte colony-stimulating factor, resulted in frequent dose adjustments (> 60% of patients). In Part C, evaluation of prexasertib + pemetrexed was halted due to dose-limiting toxicities in two of the first three patients; MTD was not established. In Part D, the MTD of prexasertib in combination with 5-fluorouracil (label dose) was declared at 40 mg /m2, both administered on Day 1 of a 14-day cycle. In Part D, overall ORR was 12.5%. CONCLUSIONS: This study demonstrated the proof-of-concept that prexasertib can be combined with cisplatin, cetuximab, and 5-fluorouracil. Schedule was a key determinant of the tolerability and feasibility of combining prexasertib with these standard-of-care agents. Reversible hematologic toxicity was the most frequent AE and was dose-limiting. Insights gleaned from this study will inform future combination strategies for the development of prexasertib and next-generation CHK1 inhibitors. CLINICALTRIALS. GOV IDENTIFIER: NCT02124148 (date of registration 28 April 2014).

A Phase II Trial of Prexasertib (LY2606368) in Patients With Extensive-Stage Small-Cell Lung Cancer.

BACKGROUND: This study assessed the checkpoint kinase 1 inhibitor prexasertib in patients with extensive-stage small-cell lung cancer (ED-SCLC). PATIENTS AND METHODS: This was a parallel-cohort phase II study of 105 mg/m2 prexasertib once every 14 days for patients who progressed after no more than two prior therapies and had platinum-sensitive (Cohort 1) or platinum-resistant/platinum-refractory (Cohort 2) disease. The primary endpoint was objective response rate (ORR). Secondary endpoints included disease control rate (DCR), progression-free survival (PFS), overall survival (OS), safety, and pharmacokinetics. Exploratory endpoints included biomarker identification and assessment of an alternative regimen (Cohort 3: 40 mg/m2 days 1-3, 14-day cycle). RESULTS: In Cohort 1 (n = 58), ORR was 5.2%; DCR, 31%; median PFS, 1.41 months (95% confidence interval [CI], 1.31-1.64); and median OS, 5.42 months (95% CI, 3.75-8.51). In Cohort 2 (n = 60), ORR was 0%; DCR, 20%; median PFS, 1.36 months (95% CI, 1.25-1.45); and median OS, 3.15 months (95% CI, 2.27-5.52). The most frequent all-grade, related, treatment-emergent adverse events were decreased neutrophil count (Cohort 1, 69.6%; Cohort 2, 73.3%), decreased platelet count (Cohort 1, 51.8%; Cohort 2, 50.0%), decreased white blood cell count (Cohort 1, 28.6%; Cohort 2, 40.0%), and anemia (Cohort 1, 39.3%; Cohort 2, 28.3%). Eleven patients (19.6%) in Cohort 1 and one patient (1.7%) in Cohort 2 experienced grade ≥3 febrile neutropenia. Prexasertib pharmacokinetics were consistent with prior studies. Cohort 3 outcomes were similar to those of Cohorts 1 and 2. No actionable biomarkers were identified. CONCLUSION: Prexasertib did not demonstrate activity to warrant future development as monotherapy in ED-SCLC.

Phase III study of selpercatinib versus chemotherapy ± pembrolizumab in untreated RET positive non-small-cell lung cancer.

Selpercatinib, a novel, highly selective and potent, inhibitor of RET, demonstrated clinically meaningful antitumor activity with manageable toxicity in heavily pretreated and treatment-naive RET fusion-positive non-small-cell lung cancer patients in a Phase I/II clinical trial. LIBRETTO-431 (NCT04194944) is a randomized, global, multicenter, open-label, Phase III trial, evaluating selpercatinib versus carboplatin or cisplatin and pemetrexed chemotherapy with or without pembrolizumab in treatment-naive patients with locally advanced/metastatic RET fusion-positive nonsquamous non-small-cell lung cancer. The primary end point is progression-free survival by independent review. Key secondary end points include overall survival, response rate, duration of response and progression-free survival. Clinical trial registration: NCT04194944 (ClinicalTrials.gov).

A pan-cancer transcriptome analysis identifies replication fork and innate immunity genes as modifiers of response to the CHK1 inhibitor prexasertib.

The combined influence of oncogenic drivers, genomic instability, and/or DNA damage repair deficiencies increases replication stress in cancer. Cells with high replication stress rely on the upregulation of checkpoints like those governed by CHK1 for survival. Previous studies of the CHK1 inhibitor prexasertib demonstrated activity across multiple cancer types. Therefore, we sought to (1) identify markers of prexasertib sensitivity and (2) define the molecular mechanism(s) of intrinsic and acquired resistance using preclinical models representing multiple tumor types. Our findings indicate that while cyclin E dysregulation is a driving mechanism of prexasertib response, biomarkers associated with this aberration lack sufficient predictive power to render them clinically actionable for patient selection. Transcriptome analysis of a pan-cancer cell line panel and in vivo models revealed an association between expression of E2F target genes and prexasertib sensitivity and identified innate immunity genes associated with prexasertib resistance. Functional RNAi studies supported a causal role of replication fork components as modulators of prexasertib response. Mechanisms that protect cells from oncogene-induced replication stress may safeguard tumors from such stress induced by a CHK1 inhibitor, resulting in acquired drug resistance. Furthermore, resistance to prexasertib may be shaped by innate immunity.

Broad Spectrum Activity of the Checkpoint Kinase 1 Inhibitor Prexasertib as a Single Agent or Chemopotentiator Across a Range of Preclinical Pediatric Tumor Models.

PURPOSE: Checkpoint kinase 1 (CHK1) inhibitors potentiate the DNA-damaging effects of cytotoxic therapies and/or promote elevated levels of replication stress, leading to tumor cell death. Prexasertib (LY2606368) is a CHK1 small-molecule inhibitor under clinical evaluation in multiple adult and pediatric cancers. In this study, prexasertib was tested in a large panel of preclinical models of pediatric solid malignancies alone or in combination with chemotherapy. EXPERIMENTAL DESIGN: DNA damage and changes in cell signaling following in vitro prexasertib treatment in pediatric sarcoma cell lines were analyzed by Western blot and high content imaging. Antitumor activity of prexasertib as a single agent or in combination with different chemotherapies was explored in cell line-derived (CDX) and patient-derived xenograft (PDX) mouse models representing nine different pediatric cancer histologies. RESULTS: Pediatric sarcoma cell lines were highly sensitive to prexasertib treatment in vitro, resulting in activation of the DNA damage response. Two PDX models of desmoplastic small round cell tumor and one malignant rhabdoid tumor CDX model responded to prexasertib with complete regression. Prexasertib monotherapy also elicited robust responses in mouse models of rhabdomyosarcoma. Concurrent administration with chemotherapy was sufficient to overcome innate resistance or prevent acquired resistance to prexasertib in preclinical models of neuroblastoma, osteosarcoma, and Ewing sarcoma, or alveolar rhabdomyosarcoma, respectively. CONCLUSIONS: Prexasertib has significant antitumor effects as a monotherapy or in combination with chemotherapy in multiple preclinical models of pediatric cancer. These findings support further investigation of prexasertib in pediatric malignancies.

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.

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

PURPOSE: The phase I study characterized the safety, pharmacokinetics, anti-tumor activity, and recommended phase II dose/schedule of LY3164530 in patients with advanced or metastatic cancer. METHODS: Patients received LY3164530 on days 1 and 15 (Schedule 1: 300, 600, 1000, and 1250 mg) or Days 1, 8, 15, and 22 (Schedule 2: 500 and 600 mg) of each 28 days cycle. Dose escalation used a modified toxicity probability interval model. RESULTS: Dose escalation defined a maximum tolerated dose (MTD) of 1000 mg on Schedule 1 and 500 mg on Schedule 2. Treatment-emergent adverse events related to study treatment were consistent with epidermal growth factor receptor (EGFR) inhibition and included maculopapular rash/dermatitis acneiform (83%, Grade 3/4 17%), hypomagnesemia (55%, Grade 3/4 7%), paronychia (35%), fatigue (28%, Grade 3/4 3%), skin fissures (24%), and hypokalemia (21%, Grade 3/4 7%). Partial response was achieved in three patients on Schedule 2 with colorectal cancer (n = 2) or squamous cell cancer. Overall response rate (ORR) was 10.3%, disease control rate (ORR + stable disease [SD]) was 51.7 and 17.2% of patients had SD ≥ 4 months. The in vivo stability of the bispecific antibody was confirmed. Schedule 2 provided greater and more consistent inhibition of mesenchymal-epithelial transition (MET)/EGFR throughout the dosing interval than Schedule 1. CONCLUSIONS: Although this study defined the LY3164530 MTD and pharmacokinetics on both schedules, significant toxicities associated with EGFR inhibition and lack of a potential predictive biomarker limit future development. Nonetheless, the results provide insight into the development of bispecific antibody therapy.

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.

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.

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.

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 phase II study to evaluate LY2603618 in combination with gemcitabine in pancreatic cancer patients.

BACKGROUND: The aim of this study was to determine whether checkpoint kinase 1 inihibitor (CHK1), LY2603618, and gemcitabine prolong overall survival (OS) compared to gemcitabine alone in patients with unresectable pancreatic cancer. METHODS: Patients with Stage II-IV locally advanced or metastatic pancreatic cancer were randomized (2:1) to either 230 mg of LY2603618/1000 mg/m2 gemcitabine combined or 1000 mg/m2 gemcitabine alone. OS was assessed using both a Bayesian augment control model and traditional frequentist analysis for inference. Progression-free survival (PFS), overall response rate (ORR), duration of response, pharmacokinetics (PK), and safety (Common Terminology Criteria for Adverse Events [AEs] v 3.0) were also evaluated. RESULTS: Ninety-nine patients (n = 65, LY2603618/gemcitabine; n = 34, gemcitabine) were randomized (intent-to-treat population). The median OS (months) was 7.8 (range, 0.3-18.9) with LY2603618/gemcitabine and 8.3 (range, 0.8-19.1+) with gemcitabine. Similarly, in a Bayesian analysis, the study was not positive since the posterior probability that LY2603618/gemcitabine was superior to gemcitabine in improving OS was 0.3, which did not exceed the prespecified threshold of 0.8. No significant improvements in PFS, ORR, or duration of response were observed. Drug-related treatment-emergent AEs in both arms included nausea, thrombocytopenia, fatigue, and neutropenia. The severity of AEs with LY2603618/gemcitabine was comparable to gemcitabine. The LY2603618 exposure targets (AUC(0-∞) ≥21,000 ng∙hr/mL and Cmax ≥2000 ng/mL) predicted for maximum pharmacodynamic response were achieved after 230 mg of LY2603618. CONCLUSIONS: LY2603618/gemcitabine was not superior to gemcitabine for the treatment of patients with pancreatic cancer. TRIAL REGISTRATION: NCT00839332 . Clinicaltrials.gov. Date of registration: 6 February 2009.

Two Phase 1 dose-escalation studies exploring multiple regimens of litronesib (LY2523355), an Eg5 inhibitor, in patients with advanced cancer.

PURPOSE: This first-in-human report examined the recommended Phase 2 dose and schedule of litronesib, a selective allosteric kinesin Eg5 inhibitor. METHODS: Two concurrent dose-escalation studies investigated litronesib across the dose range of 0.125-16 mg/m2/day, evaluating the following schedules of administration on a 21-day cycle: Days 1, 2, 3; Days 1, 5, 9; Days 1, 8; Days 1, 5; or Days 1, 4, with or without pegfilgrastim. Best overall response was defined per Response Evaluation Criteria in Solid Tumors (RECIST Version 1.0). Pharmacokinetic (PK) evaluations were performed. Exploratory PK/pharmacodynamic analyses investigated the relationship between litronesib plasma exposure and changes in phosphohistone H3 (pHH3) levels. RESULTS: One hundred and seventeen patients with advanced malignancies were enrolled. Neutropenia was the primary dose-limiting toxicity. Prophylactic pegfilgrastim reduced neutropenia frequency and severity, allowing administration of higher litronesib doses, but increases in the incidences of mucositis and stomatitis were observed. Among 86 response-evaluable patients, 2 patients (2%) achieved partial response, both on the Days 1, 2, 3 regimen (5 and 6 mg/m2/day with pegfilgrastim), and 17 patients (20%) maintained stable disease for ≥6 cycles. Dose-dependent increases in litronesib plasma exposure were observed, with minor intra- and inter-cycle accumulation, along with exposure-dependent increases in pHH3 expression in tumor and skin biopsies. CONCLUSIONS: On the basis of the results of these studies, two regimens were selected for Phase 2 exploration: 6 mg/m2/day on Days 1, 2, 3 plus pegfilgrastim and 8 mg/m2/day on Days 1, 5, 9 plus pegfilgrastim, both on a 21-day cycle.

Phase II evaluation of LY2603618, a first-generation CHK1 inhibitor, in combination with pemetrexed in patients with advanced or metastatic non-small cell lung cancer.

Introduction LY2603618 is a selective inhibitor of checkpoint kinase 1 (CHK1) protein kinase, a key regulator of the DNA damage checkpoint, and is predicted to enhance the effects of antimetabolites, such as pemetrexed. This phase II trial assessed the overall response rate, safety, and pharmacokinetics (PK) of LY2603618 and pemetrexed in patients with non-small cell lung cancer (NSCLC). Methods In this open-label, single-arm trial, patients with advanced or metastatic NSCLC progressing after a prior first-line treatment regimen (not containing pemetrexed) and Eastern Cooperative Oncology Group performance status ≤2 received pemetrexed (500 mg/m(2), day 1) and LY2603618 (150 mg/m(2), day 2) every 21 days until disease progression. Safety was assessed using Common Terminology Criteria for Adverse Events v3.0. Serial blood samples were collected for PK analysis after LY2603618 and pemetrexed administration. Expression of p53, as measured by immunohistochemistry and genetic variant analysis, was assessed as a predictive biomarker of response. Results Fifty-five patients were enrolled in the study. No patients experienced a complete response; a partial response was observed in 5 patients (9.1 %; 90 % CI, 3.7-18.2) and stable disease in 20 patients (36.4 %). The median progression-free survival was 2.3 months (range, 0-27.1). Safety and PK of LY2603618 in combination with pemetrexed were favorable. No association between p53 status and response was observed. Conclusions There was no significant clinical activity of LY2603618 and pemetrexed combination therapy in patients with advanced NSCLC. The results were comparable with historical pemetrexed single-agent data, with similar safety and PK profiles being observed.

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/m 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.

Preclinical analyses and phase I evaluation of LY2603618 administered in combination with pemetrexed and cisplatin in patients with advanced cancer.

LY2603618 is an inhibitor of checkpoint kinase 1 (CHK1), an important regulator of the DNA damage checkpoints. Preclinical experiments analyzed NCI-H2122 and NCI-H441 NSCLC cell lines and in vitro/in vivo models treated with pemetrexed and LY2603618 to provide rationale for evaluating this combination in a clinical setting. Combination treatment of LY2603618 with pemetrexed arrested DNA synthesis following initiation of S-phase in cells. Experiments with tumor-bearing mice administered the combination of LY2603618 and pemetrexed demonstrated a significant increase of growth inhibition of NCI-H2122 (H2122) and NCI-H441 (H441) xenograft tumors. These data informed the clinical assessment of LY2603618 in a seamless phase I/II study, which administered pemetrexed (500 mg/m(2)) and cisplatin (75 mg/m(2)) and escalating doses of LY2603618: 130-275 mg. Patients were assessed for safety, toxicity, and pharmacokinetics. In phase I, 14 patients were enrolled, and the most frequently reported adverse events included fatigue, nausea, pyrexia, neutropenia, and vomiting. No DLTs were reported at the tested doses. The systemic exposure of LY2603618 increased in a dose-dependent manner. Pharmacokinetic parameters that correlate with the maximal pharmacodynamic effect in nonclinical xenograft models were achieved at doses ≥240 mg. The pharmacokinetics of LY2603618, pemetrexed, and cisplatin were not altered when used in combination. Two patients achieved a confirmed partial response (both non-small cell lung cancer), and 8 patients had stable disease. LY2603618 administered in combination with pemetrexed and cisplatin demonstrated an acceptable safety profile. The recommended phase II dose of LY2603618 was 275 mg.