Potential utility of a longitudinal relative dose intensity of molecularly targeted agents in phase 1 dose-finding trials.

Phase 1 trials of molecularly targeted agents (MTA) often do not use toxicity data beyond the first cycle of treatment to determine a recommended phase 2 dose (RP2D). We investigated the potential utility of longitudinal relative dose intensity (RDI) that may be a better new way of determining a more accurate RP2D as a lower dose that is presumably more tolerable over the long term without compromising efficacy. All consecutive patients who were initially treated using a single MTA at the conventional RP2D or at one level lower dose (OLLD) of that RP2D in 9 phase 1 trials sponsored by the National Cancer Institute were included. The associations between longitudinal RDI, time to first progression, and response rate were analyzed. The RDI of the conventional RP2D group were maintained a rate of ≥70% throughout 10 cycles, and were higher than those of the OLLD group, although in both groups the RDI gradually decreased with additional treatment cycles. The RP2D group was similar to the OLLD group with respect to time to first progression and response rate. In both groups, however, the decreasing RDI over time was significantly associated with shorter time to first disease progression; therefore, the longitudinal RDI, which takes into account lower grade toxicity occurrences, may be useful in determining a more desirable dose to use in phase 2 and 3 studies.

The Effect of Hepatic Impairment on Outcomes in Phase I Clinical Trials in Cancer Subjects.

PURPOSE: The NCI Cancer Therapy Evaluation Program sponsors hepatic dysfunction phase I clinical trials (HDCT) and phase 1 clinical trials (P1CT) to determine safe doses and schedules of antineoplastic therapeutics. We sought to compare clinical outcomes between these trial types while stratifying by hepatotoxic agents. EXPERIMENTAL DESIGN: Individual subject data were extracted from the records of 51 NCI-sponsored HDCT and P1CT. The NCI's Organ Dysfunction Working Group's hepatic impairment categorization and two drug-induced liver injury (DILI) scales (FDA R ratio and Hy's law) were used to classify subjects. The number of cycles administered and treatment discontinuation reason were also evaluated and compared between groups. RESULTS: There were 513 and 1,328 subjects treated on HDCT (n = 9) and P1CT (n = 42), respectively. There were differing patterns of DILI with significant worsening of total bilirubin in subjects on HDCT, and worsening of alanine aminotransferase (ALT) in subjects on P1CT. Cholestatic peak patterns of liver impairment (predominant increases in alkaline phosphatase rather than transaminases) were more frequent in HDCT. Criteria for Hy's law were met by 11 subjects on P1CT, but not by any subjects on HDCT. Disease progression was the most common reason for treatment discontinuation, followed by adverse events at similar frequencies in both HDCT and P1CT. CONCLUSIONS: The differential effects on hepatotoxicity suggest that underlying hepatic function may affect susceptibility to and patterns of DILI. The incorporation of additional measures of hepatic function may help identify those at highest risk of hepatotoxicity in future trials because baseline liver tests did not. Clin Cancer Res; 22(22); 5472-9. ©2016 AACR.

Targeting Notch, Hedgehog, and Wnt pathways in cancer stem cells: clinical update.

During the past decade, cancer stem cells (CSCs) have been increasingly identified in many malignancies. Although the origin and plasticity of these cells remain controversial, tumour heterogeneity and the presence of small populations of cells with stem-like characteristics is established in most malignancies. CSCs display many features of embryonic or tissue stem cells, and typically demonstrate persistent activation of one or more highly conserved signal transduction pathways involved in development and tissue homeostasis, including the Notch, Hedgehog (HH), and Wnt pathways. CSCs generally have slow growth rates and are resistant to chemotherapy and/or radiotherapy. Thus, new treatment strategies targeting these pathways to control stem-cell replication, survival and differentiation are under development. Herein, we provide an update on the latest advances in the clinical development of such approaches, and discuss strategies for overcoming CSC-associated primary or acquired resistance to cancer treatment. Given the crosstalk between the different embryonic developmental signalling pathways, as well as other pathways, designing clinical trials that target CSCs with rational combinations of agents to inhibit possible compensatory escape mechanisms could be of particular importance. We also share our views on the future directions for targeting CSCs to advance the clinical development of these classes of agents.

Targeting embryonic signaling pathways in cancer therapy.

INTRODUCTION: The embryonic signaling pathways (ESP), Hedgehog, Notch and Wnt, are critical for the regulation of normal stem cells and cellular development processes. They are also activated in the majority of cancers. ESP are operational in putative cancer stem cells (CSC), which drive initial tumorigenesis and sustain cancer progression and recurrence in non-CSC bulk subpopulations. ESP represent novel therapeutic targets. A variety of inhibitors and targeting strategies are being developed. AREAS COVERED: This review discusses the rationale for targeting ESP for cancer treatment, as well as specific inhibitors under development; mainly focusing on those approaching clinical use and the challenges that lie ahead. The data sources utilized are several database search engines (PubMed, Google, Clinicaltrials.gov), and the authors' involvement in the field. EXPERT OPINION: CSC research is rapidly evolving. Expectations regarding their therapeutic targeting are rising quickly. Further definition of what constitutes a true CSC, proper validation of CSC markers, a better understanding of cross-talk among ESP and other pathways, and interactions with tumor non-CSC and the tumor microenvironment are needed. The appropriate patient population, the right clinical setting and combination strategies to test these therapies, as well as the proper pharmacodynamic markers to measure, need to be further established.

Emerging therapeutics for advanced thyroid malignancies: rationale and targeted approaches.

INTRODUCTION: Thyroid cancer is an emerging public health concern. In the USA, its incidence has doubled in the past decade, making it the eighth most commonly diagnosed neoplasm in 2010. Despite this alarming increase, most thyroid cancer patients benefit from conventional approaches (surgery, radioiodine, radiotherapy, TSH suppression with levothyroxine) and are often cured. Nevertheless, a minority have aggressive tumors resistant to cytotoxic and other historical therapies; these patients sorely need new treatment options. AREAS COVERED: Herein the biology and molecular characteristics of the common histological types of thyroid cancer are reviewed to provide context for subsequent discussion of recent developments and emerging therapeutics for advanced thyroid cancers. EXPERT OPINION: Several kinase inhibitors, especially those targeting VEGFR and/or RET, have already demonstrated promising activity in differentiated and medullary thyroid cancers (DTC, MTC). Although of minimal benefit in DTC and MTC, cytotoxic chemotherapy with anti-microtubule agents and/or anthracyclines in combination with intensity-modulated radiation therapy appears to extend survival for patients with locoregionally confined anaplastic thyroid cancer (ATC), but to have only modest benefit in metastatic ATC. Further discovery and development of novel agents and combinations of agents will be critical to further progress in treating advanced thyroid cancers of all histotypes.

Molecular conversations and the development of the hair follicle and basal cell carcinoma.

The understanding of the anatomy and development of fetal and adult hair follicles and the molecular study of the major embryonic pathways that regulate the hair follicle have led to exciting discoveries concerning the development of basal cell carcinoma (BCC). These studies have shed light on the major roles of Sonic hedgehog (Shh) signaling and its interactions with the insulin-like growth factor (IGF) axis in BCC development. New work, for example, explores a link between Shh signaling and IGF binding protein-2 (IGFBP-2) in the hair follicle as it transforms into BCC. IGFBP-2 was overexpressed in specific hair follicle cells of mice with ectopically activated Shh signaling [keratin 14 (K14)-Cre: patched homologue 1 (Cre: Ptch1)(lox/lox) mice]. Ptch1 deletion resulted in both an expansion of the stem cell niche and inhibition of cell differentiation. In transformed hair follicles, IGFBP-2 mediates epidermal progenitor cell expansion. Evidence also indicated that IGFBP-2 is expressed in human BCC.