A Phase II Trial of the WEE1 Inhibitor Adavosertib in SETD2-Altered Advanced Solid Tumor Malignancies (NCI 10170).

PURPOSE: Evaluate the efficacy of WEE1 inhibitor adavosertib in patients (pts) with solid tumor malignancies (cohort A) and clear cell renal cell carcinoma (ccRCC; cohort B). PATIENTS AND METHODS: NCT03284385 was a parallel cohort, Simon two-stage, phase II study of adavosertib (300 mg QDAY by mouth on days 1-5 and 8-12 of each 21-day cycle) in pts with solid tumor malignancies harboring a pathogenic SETD2 mutation. The primary endpoint was objective response rate (ORR). Correlative assays evaluated loss of H3K36me3 by immunohistochemistry (IHC), a downstream consequence of SETD2 loss, in archival tumor tissue. RESULTS: Eighteen pts were enrolled (9/cohort). Median age was 60 years (range 45 - 74). The median duration of treatment was 1.28 months (range 0 - 24+). No objective responses were observed in either cohort; accrual was halted following stage 1. Minor tumor regressions were observed in 4/18 (22%) evaluable pts. Stable disease (SD) was the best overall response in 10/18 (56%) pts, including three pts with SD >4 months. One pt with ccRCC remains on treatment for >24 months. The most common adverse events (AE) of any grade were nausea (59%), anemia (41%), diarrhea (41%), and neutropenia (41%). Nine pts (50%) experienced a Grade ≥ 3 AE. Of 8 evaluable archival tissue samples, 6 (75%) had loss of H3K36me3 by IHC. CONCLUSIONS: Adavosertib failed to exhibit objective responses in SETD2-altered ccRCC and other solid tumor malignancies though prolonged stable disease was observed in a subset of pts. Combination approaches may yield greater depth of tumor response.

NCI 7977: A Phase I Dose-Escalation Study of Intermittent Oral ABT-888 (Veliparib) plus Intravenous Irinotecan Administered in Patients with Advanced Solid Tumors.

Purpose: Veliparib is a PARP inhibitor (PARPi) with activity in BRCA 1/2/PALB2-deficient tumors. Preclinical observations reveal topoisomerase inhibitors like irinotecan are synergistic with PARPi irrespective of homologous recombination deficiency (HRD), potentially expanding the role for PARPi. Experimental Design: NCI 7977 was a multicohort phase I clinical trial evaluating the safety and efficacy of multiple dose schedules of veliparib with irinotecan for solid tumors. In the intermittent veliparib cohort, escalating doses of veliparib were given twice daily at dose level (DL) 1 (50 mg) and DL 2 (100 mg) days 1-4 and 8-11 with irinotecan 100 mg/m2 days 3 and 10 in 21-day cycles. Results: Fifteen patients enrolled, 8 of 15 (53%) received ≥4 prior systemic treatments. At DL1, 1 of 6 patients experienced a dose-limiting toxicity (DLT) of diarrhea. At DL2, 9 patients were treated, with 3 unevaluable for DLT, and 2 of 6 evaluable patients experienced a DLT of grade 3 neutropenia. Irinotecan 100 mg/m2 and veliparib 50 mg twice daily was the MTD. No objective responses were observed, although 4 patients had progression-free survival >6 months. Conclusions: The MTD of intermittent veliparib is 50 mg twice daily days 1-4 and 8-11 with weekly irinotecan 100 mg/m2 days 3 and 10 every 21 days. Multiple patients experienced prolonged stable disease irrespective of HRD and prior irinotecan. However, due to the toxicities with higher dose intermittent veliparib and irinotecan, this schedule was determined too toxic for further development and the arm was closed prematurely. Significance: The combination of intermittent veliparib with weekly irinotecan was deemed too toxic for further development. Future PARPi combinations should focus on agents with nonoverlapping toxicities to improve tolerability. The treatment combination showed limited efficacy with prolonged stable disease observed in multiple heavily pretreated patients, but no objective responses were seen.

A phase I study of ispinesib, a kinesin spindle protein inhibitor, administered weekly for three consecutive weeks of a 28-day cycle in patients with solid tumors.

PURPOSE: To establish the maximum tolerated dose (MTD), dose-limiting toxicity (DLT), safety, and pharmacokinetic profile of ispinesib when administered as a 1-h intravenous infusion weekly for three consecutive weeks of a 28 day treatment period to patients with advanced solid tumors. EXPERIMENTAL DESIGN: Thirty patients were enrolled using an initial accelerated dose-escalation phase followed by a standard dose-escalation phase at doses ranging from 1-8 mg/m(2)/week. Pharmacokinetic samples, skin punch biopsies, and tumor biopsies (in patients with accessible tumor) were obtained during cycle 1 of treatment. Disease assessment was performed every two treatment cycles. RESULTS: The MTD was defined as 7 mg/m(2) administered as a 1-h infusion weekly for three consecutive weeks of a 28 day schedule. The MTD was exceeded at 8 mg/m(2) due to DLTs of grade 2 (one patient) and grade 3 neutropenia (one patient) that resulted in the inability to administer the Day 15 dose in Cycle 1. The neutrophil nadir occurred at approximately Day 8 with a 3-7 day recovery period. The most common toxicities were nausea, diarrhea, fatigue, and neutropenia. Alopecia, mucositis, and neuropathy were not observed. Stable disease was reported as the best response to treatment in nine patients. CONCLUSION: The recommended dose of ispinesib is 7 mg/m(2) over 1 h weekly for three consecutive weeks of a 28 day treatment cycle.

Identifying treatment options for BRAFV600 wild-type metastatic melanoma: A SU2C/MRA genomics-enabled clinical trial.

Although combination BRAF and MEK inhibitors are highly effective for the 40-50% of cutaneous metastatic melanomas harboring BRAFV600 mutations, targeted agents have been ineffective for BRAFV600wild-type (wt) metastatic melanomas. The SU2C Genomics-Enabled Medicine for Melanoma Trial utilized a Simon two-stage optimal design to assess whether comprehensive genomic profiling improves selection of molecular-based therapies for BRAFV600wt metastatic melanoma patients who had progressed on standard-of-care therapy, which may include immunotherapy. Of the response-evaluable patients, binimetinib was selected for 20 patients randomized to the genomics-enabled arm, and nine were treated on the alternate treatment arm. Response rates for 27 patients treated with targeted recommendations included one (4%) partial response, 18 (67%) with stable disease, and eight (30%) with progressive disease. Post-trial genomic and protein pathway activation mapping identified additional drug classes that may be considered for future studies. Our results highlight the complexity and heterogeneity of metastatic melanomas, as well as how the lack of response in this trial may be associated with limitations including monotherapy drug selection and the dearth of available single and combination molecularly-driven therapies to treat BRAFV600wt metastatic melanomas.

Novel therapeutic inhibitors of the c-Met signaling pathway in cancer.

A wide variety of human malignancies exhibit sustained c-Met stimulation, overexpression, or mutation, including carcinomas of the breast, liver, lung, ovary, kidney, and thyroid. Notably, activating mutations in c-Met have been positively identified in patients with a particular hereditary form of papillary renal cancer, directly implicating c-Met in human tumorigenesis. Aberrant signaling of the c-Met signaling pathway due to dysregulation of the c-Met receptor or overexpression of its ligand, hepatocyte growth factor (HGF), has been associated with an aggressive phenotype. Extensive evidence that c-Met signaling is involved in the progression and spread of several cancers and an enhanced understanding of its role in disease have generated considerable interest in c-Met and HGF as major targets in cancer drug development. This has led to the development of a variety of c-Met pathway antagonists with potential clinical applications. The three main approaches of pathway-selective anticancer drug development have included antagonism of ligand/receptor interaction, inhibition of the tyrosine kinase catalytic activity, and blockade of the receptor/effector interaction. Several c-Met antagonists are now under clinical investigation. Preliminary clinical results of several of these agents, including both monoclonal antibodies and small-molecule tyrosine kinase inhibitors, have been encouraging. Several multitargeted therapies have also been under investigation in the clinic and have demonstrated promise, particularly with regard to tyrosine kinase inhibition.

PAK1 phosphorylation of MEK1 regulates fibronectin-stimulated MAPK activation.

Activation of the Ras-MAPK signal transduction pathway is necessary for biological responses both to growth factors and ECM. Here, we provide evidence that phosphorylation of S298 of MAPK kinase 1 (MEK1) by p21-activated kinase (PAK) is a site of convergence for integrin and growth factor signaling. We find that adhesion to fibronectin induces PAK1-dependent phosphorylation of MEK1 on S298 and that this phosphorylation is necessary for efficient activation of MEK1 and subsequent MAPK activation. The rapid and efficient activation of MEK and phosphorylation on S298 induced by cell adhesion to fibronectin is influenced by FAK and Src signaling and is paralleled by localization of phospho-S298 MEK1 and phospho-MAPK staining in peripheral membrane-proximal adhesion structures. We propose that FAK/Src-dependent, PAK1-mediated phosphorylation of MEK1 on S298 is central to the organization and localization of active Raf-MEK1-MAPK signaling complexes, and that formation of such complexes contributes to the adhesion dependence of growth factor signaling to MAPK.

Clinical experience of MEK inhibitors in cancer therapy.

Finding new therapies to assist in the treatment of cancer is a major challenge of clinical research. Small molecules that inhibit different molecular targets at the different levels of the MAPK pathway have been developed. Several MEK inhibitors have been examined in early-phase clinical trials and the current state of clinical results using these therapies is presented here.

A phase 2 study of vorinostat in locally advanced, recurrent, or metastatic adenoid cystic carcinoma.

PURPOSE: Vorinostat is a histone deacetylase inhibitor (HDACi). Based on a confirmed partial response (PR) in an adenoid cystic carcinoma (ACC) patient treated with vorinostat in a prior phase 1 trial, we initiated this phase 2 trial. METHODS: Vorinostat was administered orally 400 mg daily, 28 day cycles. The primary objective was to evaluate response rate (RR). Exploratory studies included whole exome sequencing (WES) of selected patients. RESULTS: Thirty patients were enrolled. Median age of patients was 53 years (range 21-73). Median number of cycles was 5 (range 1-66). Lymphopenia (n = 5), hypertension (n = 3), oral pain (n = 2), thromboembolic events (n = 2) and fatigue (n = 2) were the only grade 3 adverse events (AEs) that occurred in more than 1 patient. Eleven patients were dose reduced secondary to drug-related AEs. Two patients had a partial response (PR), with response durations of 53 and 7.2 months. One patient had a minor response with a decrease in ascites (for 19 cycles). Stable disease was the best response in 27 patients. Targeted and WES of 8 patients in this trial identified mutations in chromatin remodeling genes highlighting the role of the epigenome in ACC. CONCLUSION: Vorinostat demonstrated efficacy in patients with ACC supporting the inclusion of HDACi in future studies to treat ACC.

Non-rash skin toxicities associated with novel targeted therapies.

Many novel targeted agents have emerged against a variety of malignancies. Although papulopustular rash is the most commonly observed side effect associated with many of these agents, several non-rash skin toxicities have been identified that frequently result in the delay or discontinuation of anticancer therapy. These toxicities include skin hyperpigmentation, xerosis, pruritus, hair growth and color abnormalities, periungual and nail alterations, and hand-foot skin reaction. It is important to recognize these toxicities, so that they can be diagnosed early and treatment or dose modification can be initiated, if necessary. This review discusses several non-rash dermatologic toxicities observed with targeted therapeutic agents and guidelines for their diagnosis and treatment.

Phase I Safety, Pharmacokinetic, and Pharmacodynamic Study of the Poly(ADP-ribose) Polymerase (PARP) Inhibitor Veliparib (ABT-888) in Combination with Irinotecan in Patients with Advanced Solid Tumors.

PURPOSE: PARP is essential for recognition and repair of DNA damage. In preclinical models, PARP inhibitors modulate topoisomerase I inhibitor-mediated DNA damage. This phase I study determined the MTD, dose-limiting toxicities (DLT), pharmacokinetics (PK), and pharmacodynamics (PD) of veliparib, an orally bioavailable PARP1/2 inhibitor, in combination with irinotecan. EXPERIMENTAL DESIGN: Patients with advanced solid tumors were treated with 100 mg/m(2) irinotecan on days 1 and 8 of a 21-day cycle. Twice-daily oral dosing of veliparib (10-50 mg) occurred on days 3 to 14 (cycle 1) and days -1 to 14 (subsequent cycles) followed by a 6-day rest. PK studies were conducted with both agents alone and in combination. Paired tumor biopsies were obtained after irinotecan alone and veliparib/irinotecan to evaluate PARP1/2 inhibition and explore DNA damage signals (nuclear γ-H2AX and pNBS1). RESULTS: Thirty-five patients were treated. DLTs included fatigue, diarrhea, febrile neutropenia, and neutropenia. The MTD was 100 mg/m(2) irinotecan (days 1 and 8) combined with veliparib 40 mg twice daily (days -1-14) on a 21-day cycle. Of 31 response-evaluable patients, there were six (19%) partial responses. Veliparib exhibited linear PK, and there were no apparent PK interactions between veliparib and irinotecan. At all dose levels, veliparib reduced tumor poly(ADP-ribose) (PAR) content in the presence of irinotecan. Several samples showed increases in γ-H2AX and pNBS1 after veliparib/irinotecan compared with irinotecan alone. CONCLUSIONS: Veliparib can be safely combined with irinotecan at doses that inhibit PARP catalytic activity. Preliminary antitumor activity justifies further evaluation of the combination. Clin Cancer Res; 22(13); 3227-37. ©2016 AACR.

Protein expression of DNA damage repair proteins dictates response to topoisomerase and PARP inhibitors in triple-negative breast cancer.

Patients with metastatic triple-negative breast cancer (TNBC) have a poor prognosis. New approaches for the treatment of TNBC are needed to improve patient survival. The concept of synthetic lethality, brought about by inactivating complementary DNA repair pathways, has been proposed as a promising therapeutic option for these tumors. The TNBC tumor type has been associated with BRCA mutations, and inhibitors of Poly (ADP-ribose) polymerase (PARP), a family of proteins that facilitates DNA repair, have been shown to effectively kill BRCA defective tumors by preventing cells from repairing DNA damage, leading to a loss of cell viability and clonogenic survival. Here we present preclinical efficacy results of combining the PARP inhibitor, ABT-888, with CPT-11, a topoisomerase I inhibitor. CPT-11 binds to topoisomerase I at the replication fork, creating a bulky adduct that is recognized as damaged DNA. When DNA damage was stimulated with CPT-11, protein expression of the nucleotide excision repair enzyme ERCC1 inversely correlated with cell viability, but not clonogenic survival. However, 4 out of the 6 TNBC cells were synergistically responsive by cell viability and 5 out of the 6 TNBC cells were synergistically responsive by clonogenic survival to the combination of ABT-888 and CPT-11. In vivo, the BRCA mutant cell line MX-1 treated with CPT-11 alone demonstrated significant decreased tumor growth; this decrease was enhanced further with the addition of ABT-888. Decrease in tumor growth correlated with an increase in double strand DNA breaks as measured by γ-H2AX phosphorylation. In summary, inhibiting two arms of the DNA repair pathway simultaneously in TNBC cell lines, independent of BRCA mutation status, resulted in un-repairable DNA damage and subsequent cell death.

Pilot Trial of Selecting Molecularly Guided Therapy for Patients with Non-V600 BRAF-Mutant Metastatic Melanoma: Experience of the SU2C/MRA Melanoma Dream Team.

Targeted therapies and immunotherapies have led to significant improvements in the treatment of advanced cancers, including metastatic melanoma. However, new strategies are desperately needed to overcome therapeutic resistance to these agents, as well as to identify effective treatment approaches for cancer patients that fall outside major targetable mutational subtypes (e.g., non-V600 BRAF melanoma). One such strategy is to extend the paradigm of individually tailored, molecularly targeted therapy into a broader spectrum of melanoma patients, particularly those bearing tumors without commonly recognized therapeutic targets, as well as having failed or were ineligible for immunotherapy. In this nontreatment pilot study, next-generation sequencing (NGS) technologies were utilized, including whole genome and whole transcriptome sequencing, to identify molecular aberrations in patients with non-V600 BRAF metastatic melanoma. This information was then rationally matched to an appropriate clinical treatment from a defined pharmacopeia. Five patients with advanced non-V600 BRAF metastatic melanoma were enrolled. We demonstrated successful performance of the following during a clinically relevant time period: patient tumor biopsy, quality DNA/RNA extraction, DNA/RNA-based sequencing for gene expression analysis, analysis utilizing a series of data integration methodologies, report generation, and tumor board review with formulated treatment plan. Streamlining measures were conducted based on the experiences of enrolling, collecting specimens, and analyzing the molecular signatures of patients. We demonstrated the feasibility of using NGS to identify molecular aberrations and generate an individualized treatment plan in this patient population. A randomized treatment study utilizing lessons learned from the conduct of this pilot study is currently underway.

Meta-analysis of the relationship between dose and benefit in phase I targeted agent trials.

BACKGROUND: To date, the primary objective of phase I trials has been to safely select the maximum tolerated dose (MTD) of a drug or drug combination for utilization in subsequent trials. Although conventional cytotoxic chemotherapy is generally more effective at the MTD than molecularly targeted agents (MTAs), recent single-institution data suggest that molecularly targeted agent may not require an MTD for efficacy. We analyzed patient outcome results in MTA phase I trials at multiple institutions throughout North America sponsored by the National Cancer Institute's Cancer Therapy Evaluation Program. METHODS: We retrospectively collected and analyzed data on patients treated on monotherapy phase I trials investigating novel MTAs with a defined MTD from 2000 to 2009. Logistic regression analysis was used to test whether there was an increase in the probability of a response as dose increased. A Cox proportional hazards model was used to determine if overall survival increased with increasing dose. All statistical tests were two-sided. RESULTS: We analyzed 1908 patients treated on 55 eligible clinical trials. The probability of both overall response (complete response plus partial response) and overall survival increased with increasing dose (odds ratio for increased response = 1.56, P = .10; hazard ratio for death = 0.37, P = .008) when controlling for study as a covariate. CONCLUSIONS: Patients treated in the context of phase I trials with MTAs continue to derive reasonable clinical benefit. Contrary to other single institution data, our data suggest clinical benefit in terms of increasing response and overall survival with increasing dose.

Accelerating cancer therapy development: the importance of combination strategies and collaboration. Summary of an Institute of Medicine workshop.

Cancer cells contain multiple genetic changes in cell signaling pathways that drive abnormal cell survival, proliferation, invasion, and metastasis. Unfortunately, patients treated with single agents inhibiting only one of these pathways--even if showing an initial response--often develop resistance with subsequent relapse or progression of their cancer, typically via the activation of an alternative uninhibited pathway. Combination therapies offer the potential for inhibiting multiple targets and pathways simultaneously to more effectively kill cancer cells and prevent or delay the emergence of drug resistance. However, there are many unique challenges to developing combination therapies, including devising and applying appropriate preclinical tests and clinical trial designs, prioritizing which combination therapies to test, avoiding overlapping toxicity of multiple agents, and overcoming legal, cultural, and regulatory barriers that impede collaboration among multiple companies, organizations, and/or institutions. More effective strategies to efficiently develop combination cancer therapies are urgently needed. Thus, the Institute of Medicine's National Cancer Policy Forum recently convened a workshop with the goal of identifying barriers that may be impeding the development of combination investigational cancer therapies, as well as potential solutions to overcome those barriers, improve collaboration, and ultimately accelerate the development of promising combinations of investigational cancer therapies.

An overview of the optimal planning, design, and conduct of phase I studies of new therapeutics.

Phase I clinical trials represent the first step in bringing promising new treatments from the laboratory to the clinic. Although the importance of phase I clinical trials is widely recognized, there is currently no consensus among the scientific, medical, and statistical communities on how best to do these studies in humans. With the advent of targeted therapies, it has become evident that we need to tailor the design of phase I studies for the particular drug class under investigation and any endpoints that are being defined. The National Cancer Institute (NCI) Investigational Drug Steering Committee (IDSC) provides broad external scientific and clinical input on the design and prioritization of early-phase clinical trials with agents for which the NCI Cancer Therapy Evaluation Program (CTEP) holds an Investigational New Drug (IND) application through the U.S. Food and Drug Administration (FDA). The IDSC has formed a number of task forces and working groups, including the Clinical Trial Design Task Force and the Biomarker Working Group, many with membership from within the IDSC as well as external experts, including participants from academia, the pharmaceutical industry, and regulatory authorities. The Clinical Trials Design Taskforce sponsored a Phase I Workshop with the primary goal being to develop consensus recommendations for the optimal design of phase I studies. The primary focus included (1) efficient trial designs, (2) phase I drug combinations, and (3) appropriate statistical and correlative endpoints. In this CCR Focus series, articles summarize key aspects and recommendations on phase I studies (including combination trials), such as design, use of biomarkers, the European Union and Japanese perspectives on design, requirements for first-in-human and other phase I studies, and ensuring regulatory and International Conference on Harmonization (ICH) compliance. A final article summarizes recommendations for the design and conduct of phase II studies.

Making the investigational oncology pipeline more efficient and effective: are we headed in the right direction?

Advances in our knowledge of the molecular mechanisms involved in cancer biology have contributed to an increase in novel target-specific oncology therapeutics. Unfortunately, clinical development of new drugs is an expensive and slow process, and the patient and financial resources needed to study the vast number of potential therapies are limited, requiring novel approaches to clinical trial design and patient recruitment. In addition, traditional efficacy endpoints may not be adequate to fully determine the therapeutic worth of the new classes of targeted agents. In this new era of drug development, it has become increasingly clear that new clinical trial design paradigms that examine nontraditional endpoints have become necessary to assist in prioritizing the development of the most promising agents. It is also vital that individual patient management be considered, and the subpopulations of patients most likely to derive benefit or experience harm from a new therapy be identified as early as possible. Phase I and II clinical trials allow investigators doing clinical research the opportunity to define these critical endpoints and subpopulations early on, before conducting large-scale randomized phase III clinical trials, which require an abundance of financial and patient resources.

Translating clinical trials into meaningful outcomes.

Efforts to unravel the complex biology that is necessary to develop new therapies best suited for an individual with cancer are at a crossroads with a strained health care system and an insufficient clinical trial apparatus. The resulting failures have been described as the "valley of death." Progress into the future will require new considerations and the engagement of a broad band of stakeholders. To identify novel therapeutics that are likely to succeed in late development and to be meaningful for clinical practice, investigators will need to make a paradigm shift in designing clinical trials and endpoints while adhering to scientific rigor when interpreting results and making informed decisions. Large phase III trials that show a modest incremental benefit will continue to diminish in value for patients, clinicians, payers, and industry. Outcomes that are robust in both magnitude and application to the real world will take on increasing importance. Ensuring active participation by patients, lowering barriers to health care access, and protecting patients through health care reform are requirements for the future success of the cancer clinical research enterprise. The challenge today is to develop new approaches to translate scientific discovery into cost-effective and meaningful improvements in cancer outcomes.

A phase I study of foretinib, a multi-targeted inhibitor of c-Met and vascular endothelial growth factor receptor 2.

PURPOSE: Foretinib is an oral multikinase inhibitor targeting Met, RON, Axl, and vascular endothelial growth factor receptor. We conducted a phase I, first-time-in-human, clinical trial using escalating doses of oral foretinib. The primary objectives are to identify a maximum tolerated dose and determine the safety profile of foretinib. Secondary objectives included evaluation of plasma pharmacokinetics, long-term safety after repeated administration, preliminary antitumor activity, and pharmacodynamic activity. EXPERIMENTAL DESIGN: Patients had histologically confirmed metastatic or unresectable solid tumors for which no standard measures exist. All patients received foretinib orally for 5 consecutive days every 14 days. Dose escalation followed a conventional "3+3" design. RESULTS: Forty patients were treated in eight dose cohorts. The maximum tolerated dose was defined as 3.6 mg/kg, with a maximum administered dose of 4.5 mg/kg. Dose-limiting toxicities included grade 3 elevations in aspartate aminotransferase and lipase. Additional non-dose-limiting adverse events included hypertension, fatigue, diarrhea, vomiting, proteinuria, and hematuria. Responses were observed in two patients with papillary renal cell cancer and one patient with medullary thyroid cancer. Stable disease was identified in 22 patients. Foretinib pharmacokinetics increased linearly with dose. Pharmacodynamic evaluation indicated inhibition of MET phosphorylation and decreased proliferation in select tumor biopsies at submaximal doses. CONCLUSIONS: The recommended dose of foretinib was determined to be 240 mg, given on the first 5 days of a 14-day cycle. This dose and schedule were identified as having acceptable safety and pharmacokinetics, and will be the dose used in subsequent phase II trials.

Phase I clinical evaluation of ZD6126, a novel vascular-targeting agent, in patients with solid tumors.

BACKGROUND: ZD6126 is a novel vascular-targeting agent that disrupts the endothelial tubulin cytoskeleton causing selective occlusion of tumor vasculature and extensive tumor necrosis. This Phase I clinical study was conducted to evaluate the dose and administration schedule of ZD6126. METHODS: Adult patients with solid tumors refractory to existing treatments received a 10-min, single-dose intravenous infusion of ZD6126 every 14 or 21 days. Subsequent dose escalation was performed, based on the incidence of adverse events (AEs) within the first cycle of drug administration. Blood samples were obtained for pharmacokinetic analysis, and the effects of ZD6126 on tumor vasculature were visualized using DCE-MRI technology. RESULTS: Forty-four patients received ZD6126 (5-112 mg/m2 in the 21-day schedule, n=35; 40-80 mg/m2 in the 14-day schedule, n=9). Common AEs were similar in both groups and included abdominal pain, nausea and vomiting, which appeared to be dose related. The incidence of abdominal pain at 112 mg/m2 in the 21-day study prevented further dose escalation. Pharmacokinetic studies confirmed that ZD6126 is rapidly hydrolyzed to ZD6126 phenol. There was no difference in the pharmacokinetics of ZD6126 phenol upon repeat administration or between the two dosing regimens. DCE-MRI evaluation has demonstrated the antivascular effects of ZD6126. CONCLUSIONS: This study identified that ZD6126 administered every 2 or 3 weeks at 80 mg/m2 was well tolerated, with mild but manageable gastrointestinal AEs. In approximately 11% (5 out of 44) of patients, ZD6126 was associated with cardiac events categorized as dose limiting toxicities (one patient with asymptomatic decreased left ventricular ejection fraction (LVEF), two with increased troponin concentrations, one with myocardial ischemia, and one with ECG signs of myocardial ischemia).