Evaluation of the novel mitotic modulator ON 01910.Na in pancreatic cancer and preclinical development of an ex vivo predictive assay

The pupose of this study was to evaluate the activity of ON 01910.Na, a mitotic inhibitor, in in vitro and in vivo models of pancreatic cancer and to discover biomarkers predictive of efficacy. Successive in vitro and in vivo models were used; these included cell line-derived and patient-derived tumors from our PancXenoBank, a live collection of freshly generated pancreatic cancer xenografts. ON 01910.Na showed equivalent activity to gemcitabine against pancreatic cancer cell lines in vitro. The activity of the agent correlated with suppression of phospho-CDC25C and cyclin B1. These markers were optimized for a fine-needle aspirate ex vivo rapid assay. Cyclin B1 mRNA evaluation yielded the most optimal combination of accuracy and reproducibility. Next, nine patient-derived tumors from the PancXenoBank were profiled using the assay developed in cell lines and treated with ON01910.Na for 28 days. Two cases were cataloged as potential responders and seven as resistants. There was a correlation between the ex vivo assay and sensitivity to the tested agent, as the two cases prospectively identified as sensitive met prespecified criteria for response. Of the seven tumors of predictive resistant, only one was found to be sensitive to ON 01910.Na. In addition, there was a good correlation between cyclin B1 downregulation ex vivo and changes in cyclin B1 protein post-treatment. The novel mitotic inhibitor, ON 01910.Na, showed activity in preclinical model of pancreatic cancer. A rapid assay was rationally developed that not only identified cases sensitive to ON 01910.Na, but also anticipated the pharmacodynamic events occurring after in vivo exposure.

Germline polymorphisms in EGFR and survival in patients with lung cancer receiving gefitinib

The purpose of this study was to evaluate associations between germline epidermal growth factor receptor (EGFR) variants involved in transcriptional regulation and overall survival in white patients with non-small-cell lung cancer (NSCLC) treated with the EGFR tyrosine kinase inhibitor, gefitinib. Of 175 consecutive patients treated with oral gefitinib (250 mg/day), 170 (median age: 67 years; 72% men) were evaluable for genotyping and survival. Fifty-five patients (33%) had stable disease and 17 (10%) had an objective response. The most common of four haplotypes was G-C (EGFR*1) at the EGFR -216G>T and -191C>A loci (frequency, 0.45). After adjusting for performance status, previous platinum-containing chemotherapy and occurrence of skin rash or diarrhea during the first treatment cycle in patients with performance status 0 or 1 (N=139), the absence of EGFR*1 was associated with significantly better survival (hazard ratio: 0.54; 95% confidence interval: 0.32-0.91; P=0.015). The results may help identify patients with NSCLC who can benefit from gefitinib treatment.

Combined EGFR targeted therapy in a novel in vivo pancreas cancer model

14063

Background: EGFR inhibitors have a definite but limited activity in pancreatic cancer (PaCa). We have reported enhanced activity of dual EGFR therapy with a small molecule inhibitor (erlotinib) plus a monoclonal antibody (cetuximab) in head and neck cancer models. Human xenografted tumors recapitulate better the pathobiology of cancer than existing cell lines. Here we explored a dual EGFR targeting approach using a direct PaCa xenograft model, and sought after markers predicting efficacy. Methods: PaCa specimens obtained at the time surgery were implanted in nude mice and expanded to develop cohorts of tumor bearing mice suitable for drug evaluation. Ten cases were expanded, and within each case 4 groups of 6–8 mice each were treated with vehicle, erlotinib, cetuximab, and the combination of both for 28 days. Gene mutation analysis, gene amplification by fluorescence-in-situ hybridization, and immunohistochemistry (IHC) were done with untreated samples. Results: Two cases were sensitive to both single agents, but the combination did not induce higher efficacy in those. Two additional cases that were resistant to both single agents became sensitive with the combination. No egfr mutations were detected. Three and four cases carried low and high egfr polysomy (defined as [[Unsupported Character - ]] 4 copies in 10–40% and [[Unsupported Character - ]] 40% of the cells, respectively). No correlation was found between egfr copy number and efficacy. By IHC sensitive cases had a lower Ki67 proliferation index, and higher EGFR and nuclear pMAPK staining than resistant cases. The degree of Ki67 decrease after therapy correlated with efficacy. In cases resistant to the single agents but sensitive to the combination nuclear pMAPK only decreased with the dual targeting. Cases with high egfr polysomy were more labile to pharmacodynamic effects after treatment (such as EGFR or pMAPK decreases). Conclusions: EGFR inhibitors showed modest single agent antitumor effect that was enhanced with dual EGFR therapy in PaCa. No genomic markers predicted efficacy, although high egfr polysomy was associated with deeper pharmacodynamic inhibition, conceivably suggesting a phenomenon of pathway addiction. Higher pathway activation by IHC was linked with higher activity.

No significant financial relationships to disclose.

Pharmacodynamic-guided, modified continuous reassessment method (mCRM)-based, dose finding study of rapamycin in adult patients with solid tumors

3020

Background: Pharmacodynamic (PD) studies, using either surrogate or tumor tissues, are frequently incorporated in Phase I trials. However, it has been less common to base dose selection, the primary endpoint in Phase I trials, in PD effects. We conducted a PD-based dose selection study with rapamycin (Rap). Methods: We used the modified continuous reassessment method (mCRM), a computer-based dose escalation algorithm, and adapted the logit function from its classic toxicity-based input data to a PD-based input. We coupled this design to a Phase I trial of Rap with 2 parts: a dose estimation phase where PD endpoints are measured in normal tissues and a confirmation phase where tumor tissue is assessed. Patients (pts) had solid tumors refractory to standard therapy. Rap was given starting at 2 mg/day continuously in 3-pt cohorts. The PD endpoint was pP70S6K in skin and tumor. Biopsies were done on days 0 and 28 of cycle 1, and a PD effect was defined as ≥ 80% inhibition from baseline. The first 2 dose levels (2 and 3 mgs) were evaluated before implementing the mCRM. The data was then fed to the computer that based on the PD effect calculated the next dose level. The mCRM was set so escalation continued until a dose level elicited a PD effect and the mCRM assigned the same dose to 8 consecutive pts, at which point the effect of that dose will be confirmed in tumor biopsies. Other correlates were PET-CT and pharmacokinetics. Results: Ten pts were enrolled at doses of 2 mg (n = 4), 3 mg (n = 3) and 6 mg (n = 3). Toxicity was anemia (4 G1, 1 G2), leucopenia (1 G1, 2 G2), low ANC (2 G2), hyperglycemia (2 G1, 1 G2), hyperlipidemia (4 G1), and mucositis (1 G1, 1 G2). PD responses were seen in 2 and 1 pt at 2 and 3 mg dose levels. Input of data to the mCRM selected a dose of 6 mg for the third cohort, where PD effect was seen in 1 pt, and thus a fourth dose around 9 mg will be tested. No responses by RECIST occurred, but 2 pts had a response by PET. The PK was consistent with prior data (t1/2 24.6 ± 10.2 h, CL 31.4 ± 12.0 L/h, vol of distribution 235 ± 65 L), and exposure increased with dose. Steady-state concentration were in the 5–20 nM range. Conclusions: mCRM-based dose escalation based on real-time PD assessment is feasible and permits the exploitation of PD effects for dose selection in a rational manner.

No significant financial relationships to disclose.