Characterization of immune responses to anti-PD-1 mono and combination immunotherapy in hematopoietic humanized mice implanted with tumor xenografts

Background

The success of agents that reverse T-cell inhibitory signals, such as anti-PD-1/PD-L1 therapies, has reinvigorated cancer immunotherapy research. However, since only a minority of patients respond to single-agent therapies, methods to test the potential anti-tumor activity of rational combination therapies are still needed. Conventional murine xenograft models have been hampered by their immune-compromised status; thus, we developed a hematopoietic humanized mouse model, hu-CB-BRGS, and used it to study anti-tumor human immune responses to triple-negative breast cancer (TNBC) cell line and patient-derived colorectal cancer (CRC) xenografts (PDX).

Methods

BALB/c-Rag2^nullIl2rγ^nullSIRPα^NOD (BRGS) pups were humanized through transplantation of cord blood (CB)-derived CD34+ cells. Mice were evaluated for human chimerism in the blood and assigned into experimental untreated or nivolumab groups based on chimerism. TNBC cell lines or tumor tissue from established CRC PDX models were implanted into both flanks of humanized mice and treatments ensued once tumors reached a volume of ~150mm³. Tumors were measured twice weekly. At end of study, immune organs and tumors were collected for immunological assessment.

Results

Humanized PDX models were successfully established with a high frequency of tumor engraftment. Humanized mice treated with anti-PD-1 exhibited increased anti-tumor human T-cell responses coupled with decreased Treg and myeloid populations that correlated with tumor growth inhibition. Combination therapies with anti-PD-1 treatment in TNBC-bearing mice reduced tumor growth in multi-drug cohorts. Finally, as observed in human colorectal patients, anti-PD-1 therapy had a strong response to a microsatellite-high CRC PDX that correlated with a higher number of human CD8+ IFNγ+ T cells in the tumor.

Conclusion

Hu-CB-BRGS mice represent an in vivo model to study immune checkpoint blockade to human tumors. The human immune system in the mice is inherently suppressed, similar to a tumor microenvironment, and thus allows growth of human tumors. However, the suppression can be released by anti-PD-1 therapies and inhibit tumor growth of some tumors. The model offers ample access to lymph and tumor cells for in-depth immunological analysis. The tumor growth inhibition correlates with increased CD8 IFNγ+ tumor infiltrating T cells. These hu-CB-BRGS mice provide a relevant preclinical animal model to facilitate prioritization of hypothesis-driven combination immunotherapies.

Electronic supplementary material

The online version of this article (10.1186/s40425-019-0518-z) contains supplementary material, which is available to authorized users.

A phase II clinical trial of the Aurora and angiogenic kinase inhibitor ENMD-2076 for previously treated, advanced, or metastatic triple-negative breast cancer

Background

Triple-negative breast cancer (TNBC) remains an aggressive breast cancer subtype with limited treatment options. ENMD-2076 is a small-molecule inhibitor of Aurora and angiogenic kinases with proapoptotic and antiproliferative activity in preclinical models of TNBC.

Methods

This dual-institution, single-arm, two-stage, phase II clinical trial enrolled patients with locally advanced or metastatic TNBC previously treated with one to three prior lines of chemotherapy in the advanced setting. Patients were treated with ENMD-2076 250 mg orally once daily with continuous dosing in 4-week cycles until disease progression or unacceptable toxicity occurred. The primary endpoint was 6-month clinical benefit rate (CBR), and secondary endpoints included progression-free survival, pharmacokinetic profile, safety, and biologic correlates in archival and fresh serial tumor biopsies in a subset of patients.

Results

Forty-one patients were enrolled. The 6-month CBR was 16.7% (95% CI, 6–32.8%) and included two partial responses. The 4-month CBR was 27.8% (95% CI, 14–45.2%), and the average duration of benefit was 6.5 cycles. Common adverse events included hypertension, fatigue, diarrhea, and nausea. Treatment with ENMD-2076 resulted in a decrease in cellular proliferation and microvessel density and an increase in p53 and p73 expression, consistent with preclinical observations.

Conclusions

Single-agent ENMD-2076 treatment resulted in partial response or clinical benefit lasting more than 6 months in 16.7% of patients with pretreated, advanced, or metastatic TNBC. These results support the development of predictive biomarkers using archival and fresh tumor tissue, as well as consideration of mechanism-based combination strategies.

Trial registration

ClinicalTrials.gov, NCT01639248. Registered on July 12, 2012.

Abstract PD3-16: Clinical safety and efficacy of the aurora and angiogenic kinase inhibitor ENMD-2076 in previously treated, locally advanced or metastatic triple-negative breast cancer

Background: Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype defined by the lack of expression of the estrogen and progesterone receptors and lack of HER2 over-expression. ENMD-2076 is an orally bioavailable small molecule inhibitor of Aurora and angiogenic kinases with pro-apoptotic and antiproliferative activity in preclinical models of TNBC.

Methods: This two institution, single-arm, two-stage, phase II clinical trial enrolled patients with locally advanced or metastatic TNBC refractory to 1-3 prior lines of chemotherapy in the advanced setting. Patients had ECOG PS ≤ 1, measureable disease by RECIST 1.1 and no evidence of brain metastasis. Patients were treated with ENMD-2076 250 mg PO daily with continuous dosing in 4-week cycles until disease progression or unacceptable toxicity occurred. The primary end point was 6-month clinical benefit rate (6-CBR) and secondary endpoints included time to progression (TTP), PK profile, safety and biologic correlatives in archival and fresh serial tumor biopsies in a subset of patients.

Results: Between July 2012 and October 2016, 41 patients were enrolled (median age 54; range 30-73; female 40; male 1). Patients received a mean 1.7 prior lines of chemotherapy for locally advanced unresectable or metastatic disease and 80.5% received prior neoadjuvant or adjuvant chemotherapy (N=33). Thirty-six patients were evaluable per protocol for the primary efficacy analysis. Five patients (12.2%) were not included in the efficacy analysis due to: adverse events (AE) leading to discontinuation prior to objective efficacy assessment (N=3), not meeting eligibility criteria on day 1 (N=1) and withdraw of consent in cycle 1 (N=1). The study proceeded to the second stage of enrollment based on observing three 6-CBR events in Stage 1 (N=18 patients). The 6-CBR in the overall trial was 16.7% (95% exact CI: 6%-32.8%; 2 patients with PR and 4 patients with SD > 6 mos). The median duration of response or clinical benefit in these patients was 32 weeks (8 cycles). 4-CBR was 27.8% (95% exact CI: 14%-45.2%). Dose reduction occurred in 8 patients (20%) for fatigue, hypertension and proteinuria. The most common grade 3 treatment-related adverse events were hypertension (37.5%) and fatigue (10%). One patient experienced grade 4 hypertension. Analysis of serial tumor biopsies prior to and following 2 weeks of ENMD-2076 (N=8 patients), demonstrated a treatment-induced decrease in cellular proliferation (Ki-67) and microvessel density (CD34) as assessed by IHC. Immunofluorescence performed on a subset of samples demonstrated an increase in p53-family member expression following treatment, consistent with changes observed in preclinical TNBC patient-derived tumor xenograft models.

Conclusions: ENMD-2076 has durable clinical activity in a subset of patients with pretreated, advanced or metastatic triple-negative breast cancer. Predictive biomarker development using archival and fresh tumor tissue is underway. Exploration of lower doses of ENMD-2076 in future clinical trials may improve tolerability.

Citation Format: Diamond JR, Eckhardt SG, Pitts TM, van Bokhoven A, Aisner D, Gustafson DL, Capasso A, Elias AD, Storniolo AM, Schneider BP, Gao D, Tentler JJ, Borges VF, Miller KD. Clinical safety and efficacy of the aurora and angiogenic kinase inhibitor ENMD-2076 in previously treated, locally advanced or metastatic triple-negative breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD3-16.

Abstract P2-09-06: The role of p53 family tumor suppressors in mediating response to aurora kinase inhibition in triple-negative breast cancer

Background: Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype defined by the lack of expression of the estrogen and progesterone receptors and lack of HER2 over-expression. TNBC carries an increased risk of developing distant metastatic disease and cancer-related death. TNBC is heterogeneous in its underlying biology, however, mutations in p53 are found in approximately 80% of tumors. The purpose of this study was to utilize TNBC cell line models to investigate the role of p53 and p73 in mediating sensitivity to MLN8237, a selective Aurora kinase A inhibitor, in the setting of mutant or wildtype p53. Additionally, we used p53 and p73 knock-down models to determine the role of p53 and p73 in mediating induction of apoptosis and cellular senescence in response to Aurora kinase inhibition.

Methods: Eighteen TNBC cell lines were exposed to MLN8237 and the effects on proliferation, apoptosis, and cell cycle distribution were evaluated. Proliferation was assessed using an SRB assay, apoptosis was analyzed using a caspase 3/7 assay and cell cycle was measured using flow cytometry. Proliferation was confirmed using a cell counting technique to control for an increase in cell size following MLN8237 exposure. The p53 wildtype TNBC cell line CAL51 was transduced with several clones of shRNA constructs targeting p53 and p73 with > 80% knockdown by RT-PCR. These clones were exposed to escalating doses of MLN8237 and the effect on proliferation was determined using an SRB assay and the effect on cellular senescence was determined using a senescence associated beta-galactosidase (SA b-gal) assay.

Results: In vitro exposure to MLN8237 resulted in robust inhibition of proliferation in TNBC cell lines which was associated with dose-dependent G2/M cell cycle arrest and induction of caspase-dependent apoptosis in a subset of sensitive cell lines. Knock-down of p53 and p73 in the CAL51 cell line resulted in an increase in the absolute 50% inhibitory concentration (IC50) calculated from the SRB proliferation assay curves from 0.04 μM to > 2 μM, 1.8 μM, > 2 μM and 1.5 μM in the CAL51scr, CAL51p5310, CAL51p5312, CAL51p7326, CAL51p7355, respectively. The sensitive p53 mutated MDA-MB-468 cell line (IC50 40 nM) and the sensitive p53 wild-type CAL51 cell line (IC50 45 nM) were selected for further experimentation. Exposure to MLN8237 at concentrations of 50 nM and 100 nM for 7 days resulted in induction of cellular senescence as detected by the SA b-gal assay in the CAL51 p53 wild-type cell line, but not in the MDA-MB-468 cell line where induction of apoptosis at 48 hours was observed using the caspase 3/7 assay. In the CAL51 p73 knock-down clones, induction of cellular senescence was not observed following exposure to MLN8237.

Conclusions: MLN8237 exhibited robust anticancer activity towards preclinical models of p53 mutated and p53 wild-type TNBC, supporting future clinical investigation of Aurora kinase inhibitors in TNBC. In p53 wild-type TNBC, both p53 and p73 mediate sensitivity to MLN8237 and p73 is essential for induction of cellular senescence following exposure to MLN8237. Biomarkers predictive of response to MLN8237 in p53 mutated TNBC are being developed.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-09-06.

Medullary thyroid cancer and pseudocirrhosis: case report and literature review

Pseudocirrhosis is a rare form of liver disease that can cause clinical symptoms and radiographic signs of cirrhosis; however, its histologic features suggest a distinct pathologic process. In the setting of cancer, hepatic metastases and systemic chemotherapy are suspected causes of pseudocirrhosis. Here, we present a patient with medullary thyroid carcinoma metastatic to the liver who developed pseudocirrhosis while on maintenance sunitinib after receiving 5-fluorouracil, leucovorin, and oxaliplatin (folfox) in combination with sunitinib. Cirrhotic change in liver morphology was accompanied by diffusely infiltrative carcinomatous disease resembling the primary tumor. We discuss the diagnosis of pseudocirrhosis in this case and review the literature regarding pseudocirrhosis in cancer.

The development of regorafenib and its current and potential future role in cancer therapy

Regorafenib is a novel multikinase inhibitor that has demonstrated broad antitumor activity across various solid tumor types, in preclinical and clinical studies. Preclinical data show inhibitory activity of angiogenic, stromal and oncogenic tyrosine kinases through the targeting of vascular endothelial growth factor receptors 1, 2 and 3, tyrosine-protein kinase receptor TIE-2, platelet-derived growth factor receptor β, fibroblast growth factor receptor 1, proto-oncogene tyrosine-protein kinase receptor Ret, mast/stem cell growth factor receptor Kit, RAF proto-oncogene serine/threonine-protein kinase and wild-type and V600E mutant serine/threonine-protein kinase B-raf. Phase I trials have shown that the drug is relatively well tolerated at doses of 160 mg daily on a 3-weeks-on/1-week-off schedule, or 100 mg daily on a continuous schedule, with adverse effects typical of other multikinase inhibitors. Phase II studies demonstrated clinical benefit in a variety of tumor types, mostly associated with prolonged stable disease. Phase III studies include the CORRECT trial, which ultimately led to FDA approval of the drug in the setting of metastatic colorectal cancer previously treated with standard therapies. There is still much work to be done to determine the role of regorafenib in the future of cancer therapy. This review will focus on the development of regorafenib, from early preclinical work through phase I, II and III trials, as well as highlighting the current role and potential future directions of this novel agent.

A phase I study of sunitinib combined with modified FOLFOX6 in patients with advanced solid tumors

PURPOSE

This phase I study assessed the safety, tolerability, maximum tolerated dose (MTD), pharmacokinetics, and preliminary antitumor effects of sunitinib combined with modified FOLFOX6 (mFOLFOX6).

METHODS

Patients with advanced solid malignancies received mFOLFOX6 in 2-week cycles with escalating sunitinib doses (25, 37.5, and 50 mg/day) on three schedules: 2 weeks on, 2 weeks off (2/2); 4 weeks on, 2 weeks off (4/2); or continuous daily dosing (CDD). Patients received up to 8 treatment cycles (Schedule 2/2 and CDD schedule) or 6 cycles (Schedule 4/2). An expansion cohort enrolled patients with metastatic colorectal cancer at the Schedule 2/2 MTD.

RESULTS

Overall, 53 patients were enrolled, with 43 evaluable for dose-limiting toxicity (DLT). On Schedule 2/2 (n = 18), DLTs occurred in three patients at 50 mg/day (grade 4 neutropenia [n = 1]; grades 3 and 4 thrombocytopenia [n = 2]) and two patients achieved partial responses (PRs). On Schedule 4/2 (n = 13), 37.5 mg/day exceeded the MTD with two DLTs (febrile neutropenia and grade 4 hypokalemia, respectively). On the CDD schedule (n = 12), the MTD was 25 mg/day; one DLT (grade 3 stomatitis) was reported and two patients achieved PRs. The most common adverse events were neutropenia, fatigue, and thrombocytopenia. No clinically significant drug-drug interactions were apparent between sunitinib, its metabolite SU12662, and mFOLFOX6.

CONCLUSIONS

Sunitinib combined with mFOLFOX6 had acceptable tolerability. The MTDs were sunitinib 50 mg/day on Schedule 2/2 and 25 mg/day on the CDD schedule. A MTD for Schedule 4/2 was not established.

P3-01-08: In Vitro and In Vivo Antitumor Activity of the Aurora and Angiogenic Kinase Inhibitor ENMD-2076 in Triple-Negative Breast Cancer Models

Background

Triple-negative breast cancer (TNBC) is an aggressive biologic subtype which lacks effective targeted anti-cancer agents and is characterized by a high mitotic index and dependence on angiogenesis. ENMD-2076 is a novel orally bioavailable Aurora and angiogenic kinase inhibitor currently in clinical development with favorable pharmacokinetics and a manageable toxicity profile. The purpose of this study was to use TNBC cell line-based in vitro and in vivo models to demonstrate the antitumor activity of ENMD-2076 towards this breast cancer subtype compared to the luminal and HER2−amplified subtypes. Additionally, we used baseline gene expression profiling and pathway analysis to explore molecular predictors of responsiveness to ENMD-2076 in TNBC.

Methods: Twenty-five breast cancer cell lines were exposed to ENMD-2076 and the effects on proliferation, apoptosis, and cell cycle distribution were evaluated. Proliferation was assessed using an SRB assay, apoptosis was analyzed using a caspase 3/7 assay and cell cycle was measured using flow cytometry. In vitro activity of ENMD-2076 was confirmed in 3-D cell culture and in MDA-MB-231 and MDA-MB-468 triple-negative breast cancer xenograft models and immunohistochemical analysis was performed for phosphor-histone H3 (pHH3). Gene array and gene set enrichment analysis (GSEA) was used to identify pathways differentially regulated in the sensitive and resistance cell lines, including within the triple-negative breast cancer subset.

Results: In vitro exposure to ENMD-2076 resulted in robust inhibition of proliferation in TNBC cell lines which was associated with a G2 cell cycle arrest and induction of caspase-dependent apoptosis. Of the TNBC cell lines screened, 1 of 10 had a mean IC50 value > 5 μmol/L and 7 of 10 had a mean IC50 ≤ 1 μmol/L (Fisher's exact test, p-value = 0.009). In comparison, only 1 luminal (ER+) and one UER2-amplified breast cancer cell line had an IC50 value < 1, whereas 7 and 5 resistant lines were luminal and HER2−amplified, respectively (Fisher's exact test, p-values = 0.02 and 0.11 for ER and HER2 status, respectively). ENMD-2076 exhibited antitumor activity towards MDA-MD-231 and MDA-MB-468 xenograft models of TNBC with statistically significant tumor growth inhibition compared to vehicle control (p< 0.05 and p< 0.01, respectively). A trend towards an increase in pHH3 staining cells in the MDA-MB-231 ENMD-2076 treated group compared to the vehicle control group was observed; however, this was not statistically significant (104.7 ± 36.2 positive cells/mm2 in treated vs. 79.9 ± 34.5 in control). Using significance of analysis of microarrays (SAM) analysis and GSEA, we identified Ran, a member of the mitotic spindle regulation pathway as upregulated in sensitive TNBC cell lines (p = 0.017). Interestingly, AURKA, the main target of ENMD-2076, is a core gene in this pathway.

Conclusions: ENMD-2076 exhibited robust anticancer activity towards preclinical models of TNBC, supporting future clinical investigations of this agent in TNBC with an emphasis on the continued development of biomarkers predictive of response in this breast cancer subset.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-01-08.

A Phase I study to assess the safety, tolerability, and pharmacokinetics of AZD4877, an intravenous Eg5 inhibitor in patients with advanced solid tumors

PURPOSE

Inhibition of kinesin spindle protein or Eg5 causes the formation of monoastral mitotic spindles, which leads to cell death. AZD4877 is a specific, potent inhibitor of Eg5.

METHODS

This was a Phase I, open-label, two-part study to evaluate the maximum tolerated dose (MTD) and safety and tolerability of AZD4877 in patients with advanced solid malignancies. In part A, the MTD of AZD4877, administered as three weekly 1-h intravenous (iv) infusions in a 28-day schedule, was determined by evaluating dose-limiting toxicity (DLT). In part B, the safety, tolerability, and pharmacokinetic profile of AZD4877 at the MTD were evaluated.

RESULTS

In part A, 29 patients received at least one dose of AZD4877 (5 mg, n = 4; 7.5 mg, n = 4; 10 mg, n = 3; 15 mg, n = 3; 20 mg, n = 3; 30 mg, n = 6; 36 mg, n = 3; 45 mg, n = 3). The MTD was defined as 30 mg, with the primary DLT being neutropenia. Although exposures appeared to be similar at the AZD4877 20 and 30 mg doses, dose reductions and omissions were higher in the 30-mg cohort; therefore, an intermediate dose, 25 mg, was evaluated in part B (n = 14). In part B, neutropenia remained the most commonly reported causally related adverse event. Exposure to AZD4877 was approximately dose proportional. Severity of neutropenia was related to exposure.

CONCLUSION

The MTD of AZD4877 given as a 1-h iv infusion on days 1, 8, and 15 of a 28-day cycle was 30 mg. At the selected 25 mg dose, AZD4877 had an acceptable safety profile.

Synergistic activity of histone deacetylase and proteasome inhibition against pancreatic and hepatocellular cancer cell lines

AIM

To determine the phenotypic effects of belinostat (bel) and bortezomib (bor) against pancreatic cancer (PC) and hepatocellular cancer (HCC) cell lines.

MATERIALS AND METHODS

Antiproliferative effects were assessed using a sulforhodamine B assay. Synergy was evaluated using the Chou and Talalay method. Apoptosis was measured by caspase-3/-7 activity and PARP cleavage. Downstream effector proteins were detected via immunoblotting. Quantitative nuclear magnetic resonance (NMR)-based metabolomics analysis was performed.

RESULTS

There were single-agent antiproliferative effects against PC and HCC cell lines; the combination of bel and bor (bel+bor) had a synergistic effect. There was up to a 45-fold induction of apoptosis over the control. Post-treatment cell death was associated with p21 up-regulation, more pronounced with treatment with bel+bor. Treatment with bel+bor enhanced hyperacetylation of histone H3 over single-agent bel. A metabolic signature was established for treatments with bor and bel+bor.

CONCLUSION

The combination of bel+bor displayed significant antiproliferative activity against PC and HCC cell lines, with exhibiting synergistic antiproliferative and proapoptotic patterns even at suboptimal single-agent doses.

Contribution of the epithelial-mesenchymal (EMT) phenotype to the sensitivity of colorectal cancer cell lines to the p21-activated kinase inhibitor, PF-3758309

438

Background: Increased expression of p21–activated kinase (PAK) family proteins has been observed in a range of malignancies including those of breast, ovarian, colorectal (CRC), and pancreatic origin. PAK (PAK 1-6) proteins are critical mediators of cell proliferation, motility, transcription, and translation. In initial studies, we demonstrated that the PAK4 inhibitor, PF-3758309, exhibited robust single agent efficacy against selected CRC cell lines, with IC50s of less than 0.015 uM, whereas some cell lines were relatively resistant to the agent, with IC50s of greater than 1 uM. In subsequent gene array analyses, CRC cell lines sensitive or resistant to PF-3758309 exhibited overexpression of core genes associated with a mesenchymal or epithelial phenotype, respectively. Thus, the goal of this study was to assess the functional consequences of altering the expression of EMT-associated genes and to seek rational combination partners in CRC.

Methods: CRC cell lines that were sensitive to PF-3758309 (IC50=0.015 uM) were transfected with selected short hairpin- (sh)RNAs or micro-(mi)RNAs that are known to regulate EMT. Semi-quantitative RT-PCR and immunoblotting were performed to confirm target knockdown. The transfected cell lines were then exposed to increasing concentrations of PF-3758309 to determine the functional role of these genes in conferring responsiveness to PF-3758309.

Results: Sensitive CRC cell lines were transfected with shRNAs to Zeb1, vimentin, and caldesmon, genes that are associated with a mesenchymal phenotype. Interestingly, when the cell lines were exposed to increasing concentrations of PF- 3758309 they demonstrated a ′right shift′ towards a more resistant phenotype. Likewise, transfection with miRNA 200c, a known suppressor of Zeb1, resulted in a similar shift towards resistance.

Conclusions: These data suggest that the EMT phenotype may play a functional role in determining CRC sensitivity to the PAK4 inhibitor PF-3758309, and in addition, a rational combination targeting the epithelial phenotype with epidermal growth factor receptor inhibitors, may be warranted.

[Table: see text]

Evaluation of antiproliferative and apoptotic effects of the rational combination of the MEK1/2 inhibitor selumetinib (AZD6244) and inhibitors of the hedgehog pathway in colorectal cancer (CRC) cell lines

422

Background: The MAPK pathway is a crucial regulator of cell proliferation, survival, and resistance to apoptosis. Hyperactivation of this pathway due to mutations in KRAS have been reported in up to 50% of CRC cases. Clinical trials have shown that KRAS patients do not benefit from therapies targeting EGFR, highlighting the need for new therapeutic options. Utilizing differential gene array analyses, we have identified the hedgehog (HH) signaling pathway as a potential mediator of resistance to AZD6244. Based on these results, we tested the rational combination of selumetinib and the HH inhibitor, cyclopamine against human CRC cell lines.

Methods: CRC cell lines were exposed to varying concentrations of selumetinib and cyclopamine. For AZD6244, cell lines with IC50≤ 0.1 μM were considered extremely sensitive (ES) and those with IC50≥ 1μM were deemed extremely resistant (ER). Four KRAS mutant cell lines (2ES, 2ER) were selected for combination studies. The antiproliferative effects were assessed using the sulforhodamine B (SRB) cell viability assay, and potential synergy was evaluated using the Chou and Talalay method. Apoptosis was analyzed using bioluminescent caspase 3/7 detection.

Results: In all four cell lines tested, synergistic antiproliferative effects of selumetinib and cyclopamine were observed, including resistant lines to selumetinib. We observed significant induction of apoptosis when cell lines were exposed to the combination treatment, independent of their responsiveness to selumetinib in the SRB assay.

Conclusions: Treatment of KRAS mutant CRC cell lines with selumetinib and cyclopamine resulted in synergistic inhibition of proliferation, regardless of sensitivity to selumetinib. Interestingly, a significant increase in apoptosis was observed in response to the combination, which may explain the synergy observed by the combination index (CI). In vivo analyses of this combination in cell lines and human CRC explants are ongoing to further validate these results. These preclinical data may suggest a rational combination strategy for patients with KRAS mutant CRC.

No significant financial relationships to disclose.

Final results of a dose escalation (DE), pharmacokinetic (PK), and pharmacodynamic (PD) study of two schedules of OSI-930 in patients (pts) with advanced solid tumors

3564

Background: OSI-930 is an oral TKI with potent activity against Kit, VEGFR2, and PDGFR. Preclinical studies demonstrate tumor regression with long-term remissions across multiple xenograft models. Methods: Sequential cohorts of pts with advanced solid tumors received continuous daily OSI-930 to determine the maximum tolerated dose (MTD) and to evaluate safety, PK/PD and efficacy of OSI-930 with both QD and BID dosing. An expansion cohort was enrolled for detailed PD analysis including sVEGFR2 plasma levels, PET imaging in GIST pts or DCE-MRI in selected pts. Results: A total of 58 pts were treated (20M/38F; median 60 years (range 19–83)). OSI-930 was dosed up to 1600 mg QD without reaching MTD. 46 pts received BID dosing [mg(# pts treated)]; 400(7), 500 (31) and 600(8). DLT's were seen in 3/8 pts at 600 mg BID; G3 rash (2 pts) and G4 GGT; and 3/31 at 500 mg BID; G3 myalgia, G3 fatigue and G3 lipase. G3 hypertension was noted in 3/46 pts but not dose-limiting. Common G1/2 toxicities were fatigue (37%), diarrhea (27%), nausea (31%), and rash (24%). Objective (CA125) responses were seen in platinum-resistant ovarian cancer (2 PR/8) while in heavily pretreated GIST (median 4 prior therapies including imatinib/sunitinib), 8/18 pts achieved SD ≥12 w. Median therapy duration in the BID arm was 9 w and 18/46 pts with SD ≥12 w. PK indicated that Css were achieved after ∼7d with BID dosing. PET scans showed reduction in glycolytic activity in 4/9 pts and DCE-MRI response was seen in 4/6 pts. A trend in decreased sVEGFR levels was seen at higher doses. Conclusions: At the MTD level of 500 mg BID OSI-930 is an active, well-tolerated compound with clinically relevant antitumor activity and exposure levels consistent with antitumor activity in preclinical models. PD data indicate mechanistic proof of concept for OSI-930. OSI-930/erlotinib combination phase I study is currently enrolling.

[Table: see text]

A single-center, open-label, dose escalation, safety, and pharmacokinetic study of ENMD-1198 administered orally to patients (pts) with advanced cancer

3562

Background: ENMD-1198 (2-methoxyestra-1, 3, 5, (10) 16-tetraene-3-carboxamide), an analog of 2-methoxyestradiol (2ME2), has both antiangiogenic and antiproliferative effects in various tumor types. ENMD-1198 inhibits MT polymerization by binding to β-tubulin at the colchicine-binding site and inhibits HIF-1alpha. This Phase 1 study is evaluating the safety of ENMD-1198 to determine the maximum tolerated dose. Methods: Eligible pts had advanced cancer for which no effective therapy exists that is either evaluable by RECIST criteria or tumor markers that could be monitored for clinical benefit. Phase 1 dose escalation in 3+3 design for first 5 cohorts; modified to 1 pt cohorts for subsequent cohorts until Grade 2 treatment related toxicity, and then standard 3+3 design. All pts treated with once daily oral ENMD-1198 in 28-day cycles (with post-treatment drug-free observation period of 7–14 days in Cycle 1 only). Pts are treated until the appearance of significant treatment-emergent toxicities or disease progression (PD) occurs. Results: To date, 27 pts have been enrolled in 12 dose cohorts (range 5 to 550 mg/m2/d). Median age/performance status is 61/1. Total # of treatment cycles to date is 68, with a median of 2 cycles (range <1 to 15 cycles). Most frequent toxicities (all grades, n=22) were pain (77%), fatigue (55%), constipation (36%), neuropathy and nausea (both 32%), and anemia (27%). 4 pts have experienced stable disease (SD) for more than 2 cycles. There have been no objective responses to date. 2 pts experienced dose limiting toxicity with Grade 4 neutropenia in the 550 mg/m2/d cohort. Following drug holiday, pts restarted at 425 mg/m2/d and continued for at least 1–2 more cycles before being removed from study for PD. One pt (neuroendocrine ca pancreas) is experiencing prolonged SD at 60 mg/m2/d >14 cycles and a 2nd pt (prostate ca) experienced SD at 30mg/m2/d for 10 cycles. ENMD-1198 was absorbed rapidly after oral administration. There was a linear relationship between dose and drug exposure as measured by AUC across all doses (5 - 550 mg/m2). The elimination half-life of ENMD- 1198 averaged more than 12 hours after a single dose. Conclusions: DLT was identified at 550 mg/m2/d. Cohort expansion at 425mg/m2/d is ongoing.

[Table: see text]

Phase I trial of PX-866, a novel phosphoinositide-3-kinase (PI-3K) inhibitor

3542

Background: PX-866 is an orally available nanomolar pan-inhibitor of PI-3K whose administration results in antitumor activity and pathway (AKT, S6 and mTOR) inhibition in animal models. Loss of PTEN and/or PI 3K mutations have been associated with enhanced susceptibility to PX-866. PX-866 is being evaluated in a phase 1 clinical trial to determine the MTD, and measure safety, pharmacokinetic (PK) and pharmacodynamic (PD) endpoints in PBMCs and tumor tissue in patients with solid tumors. Methods: Patients with advanced metastatic cancers receive PX-866 orally once daily for 5 of 7 days for 2 weeks in a 28-day cycle. Dose levels of 0.5, 1, 2, 3, 4.5, 6, 8, and 10 mg are planned. PK and PD samples are collected days 1, 2, 5, 8, 12, and 15 of cycle one and days 1 and 12 of cycle two. A PD assay has been developed that utilizes flow cytometry to test the inhibition of S6RP and mTOR in PBMC. Once the MTD of this PX-866 schedule of administration has been identified, an expansion cohort is planned to investigate tumor PD events and correlate tumor and PBMC endpoints with efficacy. Results: Four cohorts (0.5, 1, 2, 3 mg) comprising 12 patients (age 42–74, median PS 1) have completed accrual, with the 4.5 mg cohort actively enrolling. The total number of cycles to date is 30 (median 2, range 1–5+). Abdominal discomfort and mild diarrhea have been possibly associated with PX-866. No drug-related severe adverse events or dose-limiting toxicities have occurred. Of the 6 patients treated in the first 2 cohorts, 3 previously progressing patients had stable disease (SD) as best response and were on study for 105, 147 and 162+ (still active) days. Two patients (squamous cell skin cancer and melanoma) had decrease in pain allowing discontinuation of analgesics. Proof-of-concept PD studies in PBMCs evidenced a dose dependent inhibition of both p-S6RP and p-mTOR levels. Conclusions: PX-866 is a novel oral PI-3K inhibitor that is undergoing development in a clinical trial with built-in PD endpoints. PX-866 has shown to have a mild side effect profile while inducing stabilization of disease in previously progressing cancer patients. Oral PX-866 provides target inhibition even at low drug doses and inhibition is maintained for an extended time following the last dose. Updated clinical, PK and PD results will be presented.

[Table: see text]

Time-dependent effects of imatinib in human leukaemia cells: a kinetic NMR-profiling study

The goal of this study was to evaluate the time course of metabolic changes in leukaemia cells treated with the Bcr-Abl tyrosine kinase inhibitor imatinib. Human Bcr-Abl⁺ K562 cells were incubated with imatinib in a dose-escalating manner (starting at 0.1 μM with a weekly increase of 0.1 μM imatinib) for up to 5 weeks. Nuclear magnetic resonance spectroscopy and liquid-chromatography mass spectrometry were performed to assess a global metabolic profile, including glucose metabolism, energy state, lipid metabolism and drug uptake, after incubation with imatinib. Initially, imatinib treatment completely inhibited the activity of Bcr-Abl tyrosine kinase, followed by the inhibition of cell glycolytic activity and glucose uptake. This was accompanied by the increased mitochondrial activity and energy production. With escalating imatinib doses, the process of cell death rapidly progressed. Phosphocreatine and NAD⁺ concentrations began to decrease, and mitochondrial activity, as well as the glycolysis rate, was further reduced. Subsequently, the synthesis of lipids as necessary membrane precursors for apoptotic bodies was accelerated. The concentrations of the Kennedy pathway intermediates, phosphocholine and phosphatidylcholine, were reduced. After 4 weeks of exposure to imatinib, the secondary necrosis associated with decrease in the mitochondrial and glycolytic activity occurred and was followed by a shutdown of energy production and cell death. In conclusion, monitoring of metabolic changes in cells exposed to novel signal transduction modulators supplements molecular findings and provides further mechanistic insights into longitudinal changes of the mitochondrial and glycolytic pathways of oncogenesis.

A dose-ranging study of the pharmacokinetics and pharmacodynamics of the selective apoptotic antineoplastic drug (SAAND), OSI-461, in patients with advanced cancer, in the fasted and fed state

PURPOSE

To evaluate the safety, pharmacokinetics and determine the recommended dose of the selective apoptotic antineoplastic drug, OSI-461 administered on a twice-daily regimen to patients with advanced solid malignancies.

METHODS

In this phase I trial, 33 patients were treated with OSI-461 doses ranging from 400 to 1,200 mg given twice daily in 4-week cycles. Pharmacokinetic studies were performed to characterize the plasma disposition of OSI-461 and the effect of food intake on OSI-461 absorption. Secondary biomarker studies were performed to assess the biologic activity of OSI-461 including the measurement of pGSK-3beta, a PKG substrate, and pharmacogenetic studies to identify polymorphisms of CYP3A that influence drug metabolism and of ABCG2, involved in drug resistance.

RESULTS

Thirty-three patients were treated with 86 courses of OSI-461. The dose-limiting toxicities were grade 3 abdominal pain, found in one patient at the 1,000 mg BID fed dose level and all patients at the 1,200 mg BID fed dose level. There was also one episode each of grade 3 fatigue and grade 3 constipation at the 1,000 and 1,200 mg BID fed dose levels, respectively. Other common toxicities included mild to moderate fatigue, nausea, anorexia and mild elevation in bilirubin. Pharmacokinetic studies of OSI-461 revealed approximately a twofold increase in AUC(0-24) when OSI-461 was administered with food. An increase in pGSK-3beta post-dose was seen in the majority of patients and was greater at higher dose levels. No patients exhibited CYP3A4 polymorphisms, while 100% of patients were found to have the CYP3A5*3/CYP3A5*3 polymorphism. Two known polymorphisms of the ABCG2 gene, G34 --> A34 and C421 --> A421, occurred at frequencies of 11.76 and 29%, respectively.

CONCLUSIONS

Toxicity and pharmacodynamic data show that the recommended oral dose of OSI-461 is 800 mg twice daily administered with food. The drug appears to be well-tolerated, and overall bioavailability appears to be markedly increased when the drug is administered with food. These results support further disease-directed evaluations of OSI-461 at a dose of 800 mg BID in combination with other chemotherapeutic agents.

Sequence-dependent antiproliferative effects of cytotoxic drugs and epidermal growth factor receptor inhibitors

BACKGROUND

Epidermal growth factor receptor (EGFR) inhibitors are in clinical development in cancer treatment. Preclinical studies have shown potential antitumor efficacy of these agents in combination with chemotherapy or with radiotherapy. However, controversial results have been obtained in different clinical trials.

MATERIALS AND METHODS

The effects on proliferation, cell cycle distribution and induction of apoptosis of three different anti-EGFR agents (gefitinib, ZD6474, cetuximab) were evaluated in different sequences of combination with either a platinum derivative (cisplatin, carboplatin, oxaliplatin) or a taxane (docetaxel, paclitaxel) in KYSE30 cells, a model of a human cancer cell line with a functional EGFR autocrine pathway.

RESULTS

The combination of a cytotoxic drug with an EGFR inhibitor caused different antiproliferative effects on KYSE30 cancer cells depending on the treatment schedule. An antagonistic effect was observed when treatment with each EGFR inhibitor was done before chemotherapy. In contrast, a synergistic antiproliferative activity was obtained when chemotherapy was followed by treatment with EGFR antagonists. This effect was accompanied by potentiation of apoptosis and arrest of the surviving cancer cells in the G(2)/M phases of the cell cycle.

CONCLUSIONS

This study provides a rationale for the evaluation of a potentially synergistic sequence of cytotoxic drugs and EGFR inhibitors in a clinical setting.

Assessment of the biological and pharmacological effects of the ανβ3 and ανβ5 integrin receptor antagonist, cilengitide (EMD 121974), in patients with advanced solid tumors

BACKGROUND

Cilengitide, an antiangiogenic agent that inhibits the binding of integrins alpha(nu)beta(3) and alpha(nu)beta(5) to the extracellular matrix, was studied at two dose levels in cancer patients to determine the optimal biological dose.

PATIENTS AND METHODS

The doses of cilengitide were 600 or 1200 mg/m(2) as a 1-h infusion twice weekly every 28 days. A novel dose escalation scheme was utilized that relied upon the biological activity rate.

RESULTS

Twenty patients received 50 courses of cilengitide with no dose-limiting toxic effects. The pharmacokinetic (PK) profile revealed a short elimination half-life of 4 h, supporting twice weekly dosing. Of the six soluble angiogenic molecules assessed, only E-selectin increased significantly from baseline. Analysis of tumor microvessel density and gene expression was not informative due to intrapatient tumor heterogeneity. Although several patients with evaluable tumor biopsy pairs did reveal posttreatment increases in tumor and endothelial cell apoptosis, these results did not reach statistical significance due to the aforementioned heterogeneity.

CONCLUSIONS

Cilengitide is a well-tolerated antiangiogenic agent. The biomarkers chosen in this study underscore the difficulty in assessing the biological activity of antiangiogenic agents in the absence of validated biological assays.

Interim results from a first-in-human study with AMG102, a fully human monoclonal antibody that neutralizes hepatocyte growth factor (HGF), the ligand to c-Met receptor, in patients (pts) with advanced solid tumors

3551

Background: AMG102 is a fully human IgG2 monoclonal antibody against HGF that prevents tumorigenesis in preclinical models through blockade of the HGF/c-Met receptor tyrosine kinase pathway. We describe interim results from the first-in-human study of AMG102. Methods: This ongoing phase 1, open-label, dose-escalation study is evaluating safety, pharmacokinetics (PK), and preliminary pharmacodynamics (PD) of AMG102 after single and multiple intravenous doses in pts with advanced solid tumors. Sequential dose cohorts of 4–6 pts were administered AMG102 at 0.5, 1, 3, 5, 10, or 20 mg/kg. Pts received a single dose, followed by a 4-wk treatment- free period during which safety and PK were assessed. If no dose-limiting toxicity (DLT) was observed, treatment was resumed every 2 wks at the same dose until pts exhibited drug intolerance or disease progression. Results: As of 10 August 2006, 31 pts have been treated with AMG102 at doses up to 20 mg/kg ( Table ). AMG102 appears to be well tolerated. One pt with non-small cell lung cancer had a grade 3 DLT of dyspnea/hypoxia after the first dose (0.5 mg/kg); a second pt with pancreatic cancer had a grade 3 DLT/serious adverse event of gastrointestinal hemorrhage after the first dose (1 mg/kg). The most frequently reported, treatment-related adverse events (AEs) have been fatigue (13%), constipation (10%), anorexia (6%), nausea (6%), and vomiting (6%). No anti-AMG102 antibodies have been detected. Initial PK analysis indicates approximately linear PK in the dose range of 0.5 to 20 mg/kg. The overall mean (SD) [median] clearance and half-life estimates based on day-1 dosing were 12.1 (5.21) [10.7] mL/hr and 15.4 (5.84) [15.5] days, respectively. Tumor response is described ( Table ). Conclusions: In this study, interim results suggest that AMG102 at doses up to 20 mg/kg appears to be well-tolerated, with preliminary PK data supporting every-2-wk administration.

[Table: see text]

No significant financial relationships to disclose.

First-in-human study of the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of PF-00299804, a small molecule irreversible panHER inhibitor in patients with advanced cancer

3599

Background: There are scientific rationale for inhibitors which provide combined and irreversible blockade of HER family members. PF-00299804 is an orally available, potent, irreversible small molecule inhibitor of the HER tyrosine kinases. Methods: The safety, tolerability, PK, PD, and efficacy of PF-00299804 administered orally once daily in 3-week cycles were assessed in patients with advanced solid tumors using an accelerated dose-escalation design. Safety assessments included adverse event (AE), laboratory, ECG, and LVEF assessments. PK parameters were determined after a single lead-in dose and on Day 14 by non-compartmental techniques. PD measures included assessment of HER-related signaling pathways via IHC analyses of serial skin and, in some patients, tumor biopsies. Serial 18F-FDG- PET/CT has been performed on a subset of patients with scans being classified according to modified EORTC criteria by a central reader. Results: 32 pts have been treated across 8 sequential dose levels ranging from 0.5 to 60 mg. The most common AEs were diarrhea, fatigue, nausea, and rash. 3/6 patients at 60 mg experienced a DLT [hand-foot syndrome (1), dehydration related to diarrhea(1), mucositis(1)]. Cmax and AUC of PF-00299804 increased with dose in an approximately proportional manner. Accumulation ranged from 3.3 to 6.8, suggesting a terminal t1/2>24 h. At the 30 mg dose level, mean Day 14 drug concentration was above the predicted efficacious concentration for tumor growth inhibition based on A431 xenograft model. Of 7 sets of PET data evaluated thus far, partial responses (PR) have been observed in 2 patients. A PR as assessed using RECIST criteria has been reported in 1 of 2 patients with advanced refractory NSCLC treated to date. Conclusions: Daily administration of PF-00299804 across many dose levels appears safe and tolerable. Diarrhea, fatigue, nausea, and rash are the most frequent AEs. Evaluation of 45 mg/d as the potential MTD is ongoing. Systemic exposures at doses = 30 mg exceed the threshold for efficacy as predicted from preclinical studies. Clinical and biological activity of PF-00299804 was observed including a PR in 1 of 2 patients with advanced refractory NSCLC.

No significant financial relationships to disclose.

Phase 1, pharmacokinetic (PK) and pharmacodynamic (PD) study of oral alvespimycin (A; KOS-1022; 17-DMAG): Two different schedules in patients with advanced malignancies

14059

Background: A is ∼3–5 fold more potent compared to 17-AAG (the first Hsp90 inhibitor to enter clinical testing), based on in vitro cytotoxicity or the MTD in toxicology studies; it is water-soluble; and oral bioavailability in dogs is estimated at 40%. Toxicity in the dog included kidney, intestinal and liver findings. This study was conducted to determine the toxicity, MTD, recommended phase 2 dose (RP2D), PK and PD of A in pts with solid tumors. Methods: Escalating doses of A were given PO on 2 different schedules: every other day or daily for 4 out of 6 weeks. An initial IV dose was given to calculate absolute bioavailability. PK was evaluated after the IV dose, Day 1 and 21 of oral dosing. PBLs were collected to investigate changes in intracellular signaling proteins by immunoblot (Days 1 and 21 at 1, 3, 24 and 48 hours post-dose). Results: 28 pts were enrolled: 24 on the QOD schedule at doses of 5 (n=4), 10 (n=4), 20 (n=8), 30 (n=5) and 40 mg (n=3); 4 pts received 10mg on the QD schedule. 50% were male, median age/ECOG PS 55 and 0; median prior regimen 3. DLT has not yet been observed. Common drug-related toxicities (n=23): fatigue 43%, nausea 24%, anorexia 19%, proteinuria 19%, and peripheral edema 14%. Of these, fatigue and peripheral edema appear to be possibly dose-related. Drug-related Grade 3–4 toxicity (one patient each) included anemia, neutropenia, peripheral edema, hypokalemia, pain in extremity and hypoxia. For pts with full PK data (n=14), bioavailability equaled 51% and 49% on Day 1 and 21, and was not dose-dependent. Mean Day 21 AUCinf for the 5 to 30 mg/m2 levels equaled 91, 166, 542 and 1889 ng*h/mL. One pt with 3-fold increase in AUCinf comparing Day 1 and 21 dose had been started on dronabinol, a CYP2C9 inhibitor. One pt with fibrosarcoma (4 prior regimens) had necrotic changes in the tumor in the axilla with improved symptoms (active at 5+ months). Additional pts with SD include hemangioendothelioma (7 months), melanoma (6+ months), and renal cell (5 months). Induction in Hsp70 at the 30 mg dose level was seen pre-dose on Day 21 with maximal induction at 24 hours post-dose. Conclusions: Dose escalation continues on both schedules in order to define a RP2D. Toxicity is acceptable. Early signs of activity have been observed.

[Table: see text]

The farnesyl transferase inhibitor, tipifarnib, is a potent inhibitor of the MDR1 gene product, P-glycoprotein, and demonstrates significant cytotoxic synergism against human leukemia cell lines

Farnesyl transferase inhibitors (FTIs) target signal-transduction pathways responsible for the proliferation and survival of hematologic malignancies, including acute myelogenous leukemias (AML). Lonafarnib has been shown to be a potent inhibitor of Pgp-mediated drug efflux. On the basis of these findings, we examined the Pgp-inhibitory properties of tipifarnib and assessed its activity when combined with anthracyclines. The effects of tipifarnib on cell proliferation, induction of apoptosis and inhibition of Pgp-mediated anthracycline efflux were analyzed in two human leukemia cell lines overexpressing Pgp (CCRF-CEM and KG1a). Measurement of residual daunorubicin (DNR)-mediated fluorescence after incubation with DNR and tipifarnib demonstrated that tipifarnib significantly inhibited DNR efflux in CCRF-CEM with an IC(50) value less than 0.5 microM. Proliferation and apoptosis assays after exposure to DNR in the presence or absence of tipifarnib demonstrated synergistic inhibition of cellular proliferation, and induction of apoptosis with the combination of tipifarnib and DNR. Similar data was obtained with an enantiomer of tipifarnib that possesses no FTI activity. Incubation with tipifarnib and DNR did not interfere with inhibition of the post-translational processing of HDJ-2. These data suggest that tipifarnib possesses Pgp-inhibitory activity in addition to its FTI activity. In high risk and refractory patients these properties may be exploited as a dual targeting mechanism in the therapy of AML.

A phase I safety, pharmacological and biological study of the farnesyl protein transferase inhibitor, tipifarnib and capecitabine in advanced solid tumors

BACKGROUND

To evaluate the toxicity and pharmacological and biological properties of the farnesyl protein transferase (FPTase) inhibitor, tipifarnib (R115777, ZARNESTRAtrade mark) and capecitabine administered for 14 days every 3 weeks.

PATIENTS AND METHODS

Patients with advanced cancers received twice daily tipifarnib (100-500 mg) and capecitabine (1000-1125 mg/m(2)) for 14 days every 3 weeks. Pharmacokinetics of tipifarnib, capecitabine and 5-fluorouracil (5-FU) were determined. Peripheral blood mononuclear cells were analyzed for farnesylation of the HDJ2 chaperone protein and FPTase activity.

RESULTS

Forty-one patients received 185 courses of treatment. Diarrhea and palmar-plantar erythrodysesthesia were dose limiting at 300 mg tipifarnib/1125 mg/m(2) capecitabine b.i.d. When the capecitabine dose was fixed at 1000 mg/m(2) b.i.d., neutropenia was dose limiting at 400 and 500 mg b.i.d. of tipifarnib. Capecitabine did not affect the pharmacology of tipifarnib at 100-300 mg b.i.d., although tipifarnib significantly increased the C(max) of 5-FU at 400 mg b.i.d. HDJ2 farnesylation and FPTase activity decreased between 200 and 400 mg b.i.d. doses of tipifarnib, without a dose-response relationship. Five patients demonstrated partial remissions and 11 patients maintained prolonged stable disease.

CONCLUSIONS

Tipifarnib and capecitabine are well tolerated at 300 mg/1000 mg/m(2) b.i.d., respectively, resulting in biologically relevant plasma concentrations and antitumor activity. The recommended dose for further disease-focused studies is 300 mg b.i.d. tipifarnib and 1000 mg/m(2) b.i.d. capecitabine, given for 14 days every 3 weeks.

Antitumor activity of the combination of cetuximab, an anti-EGFR blocking monoclonal antibody and ZD6474, an inhibitor of VEGFR and EGFR tyrosine kinases

13170

Background: The epidermal growth factor receptor (EGFR) autocrine pathway plays an important role in cancer cell growth. Vascular endothelial growth factor A (VEGF-A) is a key regulator of tumor-induced endothelial cell proliferation and vascular permeability. ZD6474 (ZACTIMA™) is an orally available, small molecule inhibitor of VEGF receptor-2 (VEGFR-2), EGFR and RET tyrosine kinase activity. We investigated the activity of ZD6474 in combination with cetuximab, an anti-EGFR blocking monoclonal antibody, to determine the antitumor activity of EGFR blockade through the combined use of two agents targeting the receptor at different molecular sites in cancer cells and of VEGFR-2 blockade in endothelial cells. Methods: The antitumor activity in vitro and in vivo of ZD6474 and/or cetuximab was tested in human cancer cell lines with a functional EGFR autocrine pathway. Results: In vitro, the combination of ZD6474 and cetuximab produced synergistic growth inhibition in all cancer cell lines tested as assessed by the Chou and Talalay method. In vivo, 4 weeks of treatment with ZD6474 (75 mg/kg p.o., days 1–5 each week) or cetuximab (1 mg i.p., days 2 and 5 each week) produced a tumor growth delay of 21–28 days (P < 0.001) in nude mice bearing established human colon carcinoma (GEO) or lung adenocarcinoma (A549) cancer xenografts compared with untreated controls. Combination treatment with ZD6474 and cetuximab for 4 weeks resulted in a more marked tumor growth delay of 120–140 days compared with controls, and this was significantly greater than with either single agent therapy (P < 0.001). Following combination treatment, 3/10 A549 xenograft-bearing mice and 4/10 GEO xenograft-bearing mice had no histologic evidence of tumor at the end of the experiment. Immunohistochemical analysis of tumor samples obtained from mice treated with the two drugs in combination demonstrated a cooperative inhibition of cancer cell proliferation and an almost complete suppression of tumor angiogenesis. Conclusions: This study provides a rationale for evaluating in a clinical setting the double blockade of EGFR in combination with inhibition of VEGFR-2 signaling as cancer therapy.

[Table: see text]

KRAS mutation analysis in patients (pts) with locally advanced pancreatic cancer (LAPC) treated with gefitinib and chemoradiation therapy (CT-RT) in a phase I trial

4106

Background: Correlative studies that incorporate biomarkers to rapidly analyze response to new agents are needed. Unique to pancreatic cancer is the high incidence of KRAS mutations (over 90%). This pilot study evaluated plasma KRAS mutations for disease monitoring in LAPC pts treated on a Phase I trial combining CT-RT with the EGFR inhibitor, gefitinib. Methods: DNA was extracted from plasma of 11 pts collected at 3 timepoints: pre-gefitinib, pre-CT-RT, and post-gefitinib+CT-RT. Matched tissue DNA was obtained from 4 pts with available paraffin blocks. KRAS codon 12 mutations were detected using a two-stage RFLP-PCR assay. Cell line controls: Calu-1 (mutant KRAS) and LNCaP (wild-type KRAS). Mutations were confirmed by direct DNA sequencing. Results were related to pt clinical data. Results: KRAS mutations were detected in the pre-gefitinib plasma of 5/11 pts, and in the matched tumor tissue of 3/4 pts. Of the 5 pts with plasma KRAS mutations, 2 pts with no detectable mutant KRAS in the plasma post-gefitinib+CT-RT had overall survival of 8 and 21 months, whereas 2 pts who retained mutant KRAS had overall survival of only 2 and 5 months, and one pt withdrew early. Of the 3 tumor tissues containing mutant KRAS, the mutations were also detectable in the matched plasma in 2 pts (67%). KRAS codon 12 mutations spectrum: 4 GGT→GAT, 2 GGT→GTT and 1 GGT→AGT. Conclusions: Plasma KRAS mutations are readily detectable in LAPC pts, and the clearance or persistence of plasma KRAS mutations after treatments reflected the clinical course in some cases. The use of plasma KRAS mutation as a marker of survival and response will be further assessed in a recently approved phase I trial using a proteasome inhibitor with chemoradiation at the University of Colorado.

No significant financial relationships to disclose.

HGS-ETR1, an antibody targeting TRAIL-R1, in combination with paclitaxel and carboplatin in patients with advanced solid malignancies: Results of a phase 1 and PK study

2515

Background: HGS-ETR1 (mapatumumab) is a fully-human monoclonal antibody agonistic to the Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand Receptor 1 (TRAIL-R1, DR4). Activation of TRAIL-R1 by HGS-ETR1 initiates a caspase cascade leading to apoptosis. HGS-ETR1 in combination with platinum or taxanes results in at least additive activity in preclinical models. Phase 1 and 2 trials have demonstrated that single agent HGS-ETR1 is well tolerated. Methods: This Phase 1 study assesses the safety, tolerability, pharmacokinetics (PK) and preliminary efficacy of HGS-ETR1 in combination with standard doses of paclitaxel and carboplatin. Patients received 3, 10 or 20 mg/kg HGS-ETR1 with paclitaxel (200 mg/m2) and carboplatin (AUC 6) every 21 days for up to 6 cycles in the absence of disease progression. Results: Enrollment is complete; 28 patients have received 106 cycles of HGS-ETR1, including 12 patients in each of the 10 mg/kg and 20 mg/kg cohorts. Fourteen of 28 pts received at least 3 cycles (median = 2.5, range 1–12). Dose-limiting toxicity has been neutropenic fever (attributed to chemotherapy) and hypersensitivity (attributed to HGS-ETR1). Other non-dose limiting adverse events at least possibly related to HGS-ETR1 include fatigue, myalgia, transaminitis, anorexia and arthralgia. Preliminary analyses reveal that carboplatin and paclitaxel PK are not affected by HGS-ETR1. Similarly, the PK profile of HGS-ETR1 is not affected by paclitaxel and carboplatin, with plasma HGS-ETR1 concentrations consistent with those observed in the Phase 1 single agent trials. Three patients with NSCLC and 1 with adenocarcinoma of an unknown primary have experienced a confirmed partial response. Conclusions: HGS-ETR1 can be safely administered with carboplatin and paclitaxel. Evaluation of HGS-ETR1 in combination with other chemotherapeutic regimens is warranted.

[Table: see text]

Apo2L/TRAIL pharmacokinetics in a phase 1a trial in advanced cancer and lymphoma

3047

Background: Apo2L/TRAIL (Apo2L ligand/tumor necrosis factor-related apoptosis-inducing ligand) is the first recombinant human protein that selectively induces apoptosis or programmed cell death in cancer cells while sparing normal cells. The molecule used in this joint clinical development between Genentech, Inc. and Amgen, Inc., is an optimized recombinant human Apo2L/TRAIL protein produced in E. coli. It displays broad activity in preclinical models of a variety of solid and hematologic cancers. This is the first report of the pharmacokinetics of Apo2L/TRAIL in humans. Methods: Thirty-nine patients enrolled in a phase 1a study had PK assessments at dose levels ranging from 0.5–15 mg/kg in two cohorts, those with and those without liver metastases. Recombinant human Apo2L/TRAIL was administered as a 1-hr IV infusion for 5 consecutive days over a 21-day cycle. Serum concentrations were determined using a sensitive ELISA assay. PK calculations were performed using Non-compartmental analyses. Results: Currently Apo2L/TRAIL PK data are available for 27 patients, 15 in cohort 1 (no liver metastases) and 12 in cohort 2 (liver metastases). Mean (± SD) PK data for patients in cohort 1 and cohort 2 did not differ. PK data for cohort 1 are outlined in the table below. Apo2L/TRAIL clearance appeared proportional to dose and consistent with that predicted from nonclinical models. Cmax achieved at doses ≥ 4 mg/kg are equivalent to or greater than those displaying activity in preclinical models. There was no evidence of drug accumulation between day 1 and day 5 of treatment. Conclusions: Apo2L/TRAIL at doses which can be safely administered in humans produces serum concentrations consistent with those demonstrating efficacy in tumor xenograft models. Hepatic metastases with or without mild liver dysfunction do not appear to influence the PK of Apo2L/TRAIL.

[Table: see text]

[Table: see text]

ZD6474, an inhibitor of VEGFR and EGFR tyrosine kinases, blocks VEGF-C-induced activation of VEGFR-3 and cell proliferation in human colon cancer cell lines

13171

Background: Vascular endothelial growth factor receptors 1, 2 and 3 (VEGFR-1, -2 and -3) have a key role in activation and proliferation of endothelial cells, with expression of VEGFR-3 largely restricted to lymphatic endothelial cells. Although high expression of VEGFR-3 and its specific ligands, VEGF-C and VEGF-D, has been associated with an increased incidence of lymph node metastasis and a poor prognosis in different human malignancies, little is known about the role of this signaling pathway in tumor cells. This study investigated VEGFR-3 and its specific ligands in human colon cancer cells, and the antiproliferative activity of ZD6474, an inhibitor of VEGFR, epidermal growth factor receptor (EGFR) and RET tyrosine kinases, and of the EGFR inhibitors gefitinib and cetuximab. Methods: The expression of VEGFRs and EGFR was determined by RT-PCR, immunoblotting, flow cytometry and immunohistochemistry in four human colon cancer cell lines (HCT-116, HT-29, HCT-15 and SW480). Secretion of transforming growth factor-α (TGF-α), VEGF-A and VEGF-C by cancer cells was determined by ELISA. The in vitro antiproliferative effects of ZD6474, gefitinib and cetuximab were determined using an MTT assay. Results: All four human colon cancer cell lines expressed functional EGFR and secreted high levels of TGF-α. All four cell lines expressed VEGFR-1 and VEGFR-3, but not VEGFR-2, and secreted both VEGF-A and VEGF-C. Treatment with ZD6474 resulted in a dose-dependent cell growth inhibition (IC50 3–5 μM), whereas treatment with gefitinib or with cetuximab produced little growth inhibition under the same culture conditions. Addition of VEGF-C induced a 2-fold increase in cell growth in vitro in all four colon cancer cell lines. Treatment with ZD6474 blocked both basal and VEGF-C-induced phosphorylation of VEGFR-3, as well as VEGF-C-induced cell proliferation. Conclusions: Human colon cancer cell lines express VEGFR-1 and VEGFR-3, and secrete VEGF-A and VEGF-C. A potential VEGF-C/VEGFR-3 autocrine loop has been identified in human colon cancer cells, which can be inhibited by ZD6474, suggesting that ZD6474 may have direct antitumor activity through inhibition of VEGFR signaling.

[Table: see text]

A phase I dose-escalation study of weekly IMC-1121B, a fully human anti-vascular endothelial growth factor receptor 2 (VEGFR2) IgG1 monoclonal antibody (Mab), in patients (pts) with advanced cancer

3032

Background: Anti-VEGFR2 antibodies are effective in a variety of preclinical leukemia and solid tumor models. IMC-1121B is a fully human anti-VEGFR2 IgG1 Mab. Methods: Cohorts of 3–6 pts (ECOG PS ≤ 2) with advanced cancer and no significant cardiovascular, thrombotic or bleeding disorders received escalating doses of IMC-1121B. A single initial dose with extended PK sampling was followed by 4 x weekly infusions per treatment cycle starting at 2mg/kg. 7 dose levels up to a maximum of 16 mg/kg are planned. Human anti-human antibodies (HAHA) directed against IMC-1121B were assessed at baseline and before each Week 4 dose. Tumor response was assessed every 2 cycles. PD analyses include DCE-MRI, serum VEGF and sVEGFR1/2 levels, and peripheral blood mononucleocyte gene expression profiling at baseline and post-dosing. Results: 12 pts (8 M; 4 F), median age 58 years (range: 36–76), have entered the study: cohort 1 (2mg/kg) n=6, cohort 2 (4mg/kg) n=4 and cohort 3 (6mg/kg) n=2. No toxicities ≥ grade 2, considered definitely or probably related to study drug, have occurred. Toxicities ≥ grade 2 possibly drug-related include anorexia, vomiting, anemia, depression, fatigue, and insomnia. To date, there has been one unconfirmed partial response (melanoma) and 5 pts with stable disease for >3 months (colon: 2, breast, gastric, thyroid). Preliminary non-compartmental PK analysis reveals dose-dependent elimination and non-linear exposure, consistent with saturable clearance mechanism(s): mean t1/2 = 63.62, 93.46, 99.63 hrs, mean Cmax = 43.67, 80.25, 264 ug/mL, and AUC0-Inf = 3860, 9242, 27437 hr*ug/mL, at the 2, 4, and 6 mg/kg dose levels, respectively. Conclusions: Weekly administration of IMC-1121B is well tolerated at doses up to 6mg/kg/week. There is early evidence of a non-linear dose-PK relationship. Dose escalation continues. Updated safety, PK, PD, HAHA, and efficacy data will be presented.

[Table: see text]

Clinical evaluation of ZD6474, an orally active inhibitor of VEGF and EGF receptor signaling, in patients with solid, malignant tumors

BACKGROUND

ZD6474 selectively inhibits the tyrosine kinase activity of vascular endothelial growth factor receptor and epidermal growth factor receptor. The safety, tolerability and pharmacokinetics of ZD6474 were assessed in a phase I dose-escalation study of patients with advanced solid tumors.

PATIENTS AND METHODS

Adult patients with tumors refractory to standard treatments received once-daily oral ZD6474 (50-600 mg) in 28-day cycles, until disease progression or unacceptable toxicity was observed.

RESULTS

Seventy-seven patients were treated at doses of 50 mg (n=9), 100 mg (n=19), 200 mg (n=8), 300 mg (n=25), 500 mg (n=8), and 600 mg (n=8). Adverse events were generally mild, and the most common dose-limiting toxicities (DLT) were diarrhea (n=4), hypertension (n=4), and rash (n=3). The incidence of most adverse events appeared to be dose-dependant. In the 500 mg/day cohort, 3/8 patients experienced DLT and this dose was therefore considered to exceed the maximum tolerated dose. Pharmacokinetic analysis confirmed that ZD6474 was suitable for once-daily oral dosing.

CONCLUSIONS

Once-daily oral dosing of ZD6474 at 300 mg/day is generally well tolerated in patients with advanced solid tumors, and this dose is being investigated in phase II trials.