Abstract 1807: Phase I trial of the combined targeting of the Hedgehog (GDC-0449) and EGFR pathways (erlotinib) in pancreatic cancer

We have demonstrated that crosstalk between the Hedgehog-GLI-GLI and EGFR signaling pathway exists and contribute to pancreatic tumorigenesis. This interaction can be abrogated by targeting both pathways simultaneously and results in a synergistic antitumor effect in vitro and in vivo in pancreatic tumor models. Based on these results we have undertaken a phase I trial of GDC-0449 (an orally administered Hedgehog pathway inhibitor) and erlotinib (EGFR tyrosine kinase inhibitor to: 1) determine the maximally tolerated dose (MTD) of GDC-0449 combined with erlotinib in unresectable solid tumors; 2) describe the adverse events associated with this treatment combination; 3) describe the responses of this treatment combination; and 4) to assess the effect of the erlotinib and GDC-0449 combination on selected biomarkers in circulating tumor cells (CTCs), tumor biopsies, and FDG-PET in a cohort of patients with metastatic pancreatic cancer patients treated at the MTD. During the dose escalation portion of the trial, eligible patients receive GDC-0449 150 mg p.o. daily and erlotinib 50, 75, 100, or 150 mg daily p.o. at dose levels 1, 2, 3, and 4 respectively. Eligibility criteria include: histologic proof of solid tumors that are unresectable, not amenable to any other standard therapies, or patient refused standard therapy,; ANC ≥> 1500/μL; PLT ≥> 100,000/ μL; Total bilirubin ≤< upper limit of normal (ULN); AST ≤< 3 x ULN; Creatinine ≤< 1.5 x ULN; Hemoglobin ≥> 9.0 g/dL; INR within normal limits (Cohort II [MTD Cohort] only); ECOG performance status (PS) 0, 1 or ≤ 2. For the MTD cohort, only patients with metastatic adenocarcinoma of the pancreas without prior systemic therapy for metastatic disease and tumor amenable to biopsies are eligible. Toxicity assessment is performed at each 28-day treatment cycles and response assessment every second treatment 28 day cycle. 12 patients have been entered-pancreas (3), colorectal (3), neuroendocrine (2), scc anus (2), gallbladder (1), thymoma (1). No dose-limiting toxicity (DLT) was reported at dose level 4. At the MTD, up to 20 patients with previously untreated metastatic pancreatic cancer will be entered to assess the biologic effect of GDC-0449+erlotinib. Pre- and post- treatment biopsies of metastases and FDG-PET will be performed. Weekly collection of CTCs will be undertaken and immunofluorescence microscopy of total & phosphoMAPK, EGFR, AKT, PATCHED1, GLI1, BCL-2, and quantitative PCR (Q-PCR) of PATCHED1, GLI1, and its target genes (BCL-2, BFL-1/A1, 4-1BB) will be performed. In addtion, total & phosphoMAPK, EGFR, and AKT, as well as PATCHED1, GLI1, BCL-2 by immunohistochemistry and Q-PCR of PATCHED1, GLI1, BCL-2, BFL-1/A1, 4-1BB will be analyzed in tumor biopsies. Supported by CA69912, CA136526 and CA102701.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1807.

Phase I pharmacokinetic and pharmacodynamic study of 17-dimethylaminoethylamino-17-demethoxygeldanamycin, an inhibitor of heat-shock protein 90, in patients with advanced solid tumors

PURPOSE

To define the maximum tolerated dose, toxicities, pharmacokinetics, and pharmacodynamics of 17-dimethylaminoethylamino-17-demethoxygeldanamycin (17DMAG).

METHODS

17DMAG was given intravenously over 1 hour daily for 5 days (schedule A) or daily for 3 days (schedule B) every 3 weeks. Plasma 17DMAG concentrations were measured by liquid chromatography/mass spectrometry. Heat-shock proteins (HSPs) and client proteins were evaluated at baseline and after treatment on day 1 in peripheral blood mononuclear cells (PBMCs) and in pre- and post-treatment (24 hours) biopsies done during cycle 1 at the recommended phase II dose (n = 7).

RESULTS

Fifty-six patients were entered: 26 on schedule A; 30 on schedule B. The recommended phase II doses for schedules A and B were 16 mg/m(2) and 25 mg/m(2), respectively. Grade 3/4 toxicities included liver function test elevation (14%), pneumonitis (9%), diarrhea (4%), nausea (4%), fatigue (4%) and thrombocytopenia (4%). There were no objective responses. Four patients had stable disease. 17DMAG half-life was 24 +/- 15 hours. 17DMAG area under the curve (range, 0.7 to 14.7 mg/mL x h) increased linearly with dose. The median HSP90, HSP70, and integrin-linked kinase levels were 87.5% (n = 14), 124% (n = 20), and 99.5% (n = 20) of baseline. Changes in HSPs and client proteins in tumor biopsies were not consistent between baseline and 24 hours nor did they change in the same direction as those in PBMCs collected at the time of biopsy.

CONCLUSION

The recommended phase II doses of 17DMAG (16 mg/m(2) x 5 days or 25 mg/m(2) x 3 days, every 3 weeks) are well tolerated and suitable for further evaluation.

Phase I study of 17-allylamino-17 demethoxygeldanamycin, gemcitabine and/or cisplatin in patients with refractory solid tumors

PURPOSE

To determine the maximum tolerated dose (MTD) and characterize the dose-limiting toxicities (DLT) of 17-AAG, gemcitabine and/or cisplatin. Levels of the proteins Hsp90, Hsp70 and ILK were measured in peripheral blood mononuclear cell (PMBC) lysates to assess the effects of 17-AAG.

EXPERIMENTAL DESIGN

Phase I dose-escalating trial using a "3 + 3" design performed in patients with advanced solid tumors. Once the MTD of gemcitabine + 17-AAG + cisplatin was determined, dose escalation of 17-AAG with constant doses of gemcitabine and cisplatin was attempted. After significant hematologic toxicity occurred, the protocol was amended to evaluate three cohorts: gemcitabine and 17-AAG; 17-AAG and cisplatin; and gemcitabine, 17-AAG and cisplatin with modified dosing.

RESULTS

The 39 patients enrolled were evaluable for toxicity and response. The MTD for cohort A was 154 mg/m(2) of 17-AAG, 750 mg/m(2) of gemcitabine, and 40 mg/m(2) of cisplatin. In cohort A, DLTs were observed at the higher dose level and included neutropenia, hyperbilirubinemia, dehydration, GGT elevation, hyponatremia, nausea, vomiting, and thrombocytopenia. The MTD for cohort C was 154 mg/m(2) of 17-AAG and 750 mg/m(2) of gemcitabine, with one DLT observed (alkaline phosphatase elevation) observed. In cohort C, DLTs of thrombocytopenia, fever and dyspnea were seen at the higher dose level. The remaining cohorts were closed to accrual due to toxicity. Six patients experienced partial responses. Mean Hsp90 levels were decreased and levels of Hsp70 were increased compared to baseline.

CONCLUSIONS

17-AAG in combination with gemcitabine and cisplatin demonstrated antitumor activity, but significant hematologic toxicities were encountered. 17-AAG combined with gemcitabine is tolerable and has demonstrated evidence of activity at the MTD. The recommended phase II dose is defined as 154 mg/m(2) of 17-AAG and 750 mg/m(2) of gemcitabine, and is currently being investigated in phase II studies in ovarian and pancreatic cancers. There is no recommended phase II dose for the cisplatin-containing combinations.

Abstract B56: A phase I trial of the combination of dasatinib and lapatinib

Src transduces activated HER tyrosine kinase and phosphorylates HER to further increase its activity. Src also is involved in osteoclast differentiation. We hypothesized that combining a HER tyrosine kinase inhibitor with a Src inhibitor would result in increased therapeutic activity. To address this hypothesis we performed a phase I trial of D and L to: 1)determine the maximally tolerated dose (MTD) of D combined with L; 2)describe the toxicities associated with this combination; 3)assess the pharmacokinetic (PK) interaction of L and D; 4) assess the effect of the L and D combination on circulating tumor cells (CTC) and on osteoclast precursor activation; 5)study the association of toxicity and/or tumor response with PK, and/or pharmacodynamic parameters; and 6)describe the responses of this combination. Eligibility criteria included ≥ 18 years of age, incurable solid tumors not amenable to other therapies, ANC ≥ 1500/ L, PLT ≥ 100,000/ L, total bilirubin ≤ ULN, AST ≤ 3 × ULN or AST ≤5 × ULN if liver involvement, creatinine ≤ 1.5 × ULN, Hgb ≥ 9.0 g/dL, K+ and Mg++ WNL, life expectancy ≥ 12 weeks, ejection fraction > 50%, ECOG PS 0–2, and able to swallow pills whole. In addition to standard phase I exclusion criteria patients could not have received erlotinib, sunitinib, sorafenib, gefitinib, imatinib ≤ 4 weeks prior to registration. Each agent was administered once daily on a 28 day schedule. At the MTD patients were treated with D day 1, and day 9–28 and L day 2–28 to assess PK interaction. Dose levels (mg) were #1 D 70, L 1000, #2 D 100, L 1000, #3 D 140, L 1000. 12 patients were entered on the dose escalation portion of the trial and 15 were entered at the MTD. 5 patients entered at the MTD are too early to be fully evaluable. Characteristics of evaluable patients were: median age, 63; 46% female; PS 0 (64%) 1 (27%), 1 (9%); ≥ 3 prior chemotherapies (59%). DLT was seen in 2 patients at # 3 (1 patient, grade 3 hypermagnesemia, 1, grade 3 rash) and 1 patient at # 2 (grade 3 dyspnea). The MTD was determined to be # 2. No grade 4 or 5 events have been observed in this study. 6 patients had stable disease in the dose escalation cohort. 1 (RCC) was stable disease for 6 cycles, 2 (colorectal) were stable for 5 cycles, 1 (esophagus) was stable for 3 cycles, and 2 (GIST & leiomyosarcoma) were stable for 2 cycles. Analysis of drug levels, CTCs and circulating osteoclast precursors is ongoing. There was a consistent increase in the percentage of CD11b (monocyte/macrophage/osteoclast lineage marker) positive cells in circulation as treatment progressed. However, the late osteoclast lineage marker c-Fms was not similarly increased, suggesting that the elevated CD11b reflects an inflammatory response and not activation of osteoclastogenesis. D and L is a tolerable combination at nearly full doses of each drug. Funded by a grant from Glaxo Smith Kline and Bristol Myers Squibb.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B56.

Phase I study of ipilimumab, an anti-CTLA-4 monoclonal antibody, in patients with relapsed and refractory B-cell non-Hodgkin lymphoma

PURPOSE

The growth of non-Hodgkin lymphomas can be influenced by tumor-immune system interactions. Cytotoxic T-lymphocyte antigen 4 (CTLA-4) is a negative regulator of T-cell activation that serves to dampen antitumor immune responses. Blocking anti-CTLA-4 monoclonal antibodies improves host resistance to immunogenic tumors, and the anti-CTLA-4 antibody ipilimumab (MDX-010) has clinical activity against melanoma, prostate, and ovarian cancers.

EXPERIMENTAL DESIGN

We did a phase I trial of ipilimumab in patients with relapsed/refractory B-cell lymphoma to evaluate safety, immunologic activity, and potential clinical efficacy. Treatment consisted of ipilimumab at 3 mg/kg and then monthly at 1 mg/kg x 3 months (dose level 1), with subsequent escalation to 3 mg/kg monthly x 4 months (dose level 2).

RESULTS

Eighteen patients were treated, 12 at the lower dose level and 6 at the higher dose level. Ipilimumab was generally well tolerated, with common adverse events attributed to it, including diarrhea, headache, abdominal pain, anorexia, fatigue, neutropenia, and thrombocytopenia. Two patients had clinical responses; one patient with diffuse large B-cell lymphoma had an ongoing complete response (>31 months), and one with follicular lymphoma had a partial response lasting 19 months. In 5 of 16 cases tested (31%), T-cell proliferation to recall antigens was significantly increased (>2-fold) after ipilimumab therapy.

CONCLUSIONS

Blockade of CTLA-4 signaling with the use of ipilimumab is well tolerated at the doses used and has antitumor activity in patients with B-cell lymphoma. Further evaluation of ipilimumab alone or in combination with other agents in B-cell lymphoma patients is therefore warranted.

Expression of insulin receptor isoform A and insulin-like growth factor-1 receptor in human acute myelogenous leukemia: effect of the dual-receptor inhibitor BMS-536924 in vitro

The insulin receptor (IR) and insulin-like growth factor-1 receptor (IGF1R) are receptor tyrosine kinases that participate in mitogenic and antiapoptotic signaling in normal and neoplastic epithelia. In the present study, immunoblotting and reverse transcription-PCR demonstrated expression of IGF1R and IR isoform A in acute myelogenous leukemia (AML) cell lines as well as in >80% of clinical AML isolates. Treatment with insulin enhanced signaling through the Akt and MEK1/2 pathways as well as survival of serum-starved AML cell lines. Conversely, treatment with BMS-536924, a dual IGF1R/IR kinase inhibitor that is undergoing preclinical testing, inhibited constitutive receptor phosphorylation as well as downstream signaling through MEK1/2 and Akt. These changes inhibited proliferation and, in some AML cell lines, induced apoptosis at submicromolar concentrations. Likewise, BMS-536924 inhibited leukemic colony formation in CD34+ clinical AML samples in vitro. Collectively, these results not only indicate that expression of IGF1R and IR isoform A is common in AML but also show that interruption of signaling from these receptors inhibits proliferation in clinical AML isolates. Accordingly, further investigation of IGF1R/IR axis as a potential therapeutic target in AML appears warranted.

Tanespimycin: the opportunities and challenges of targeting heat shock protein 90

BACKGROUND

Heat shock protein 90 (HSP90) is the core of a multi-chaperone complex critical for the folding, trafficking, and stabilization of many client proteins that are involved in tumor cell proliferation, survival, and angiogenesis. Targeting HSP90 results in degradation of these client proteins.

OBJECTIVE

Data supporting the development of tanespimycin, which targets HSP90, are reviewed.

METHODS

Clinical data available for tanespimycin development are presented.

RESULTS

Tanespimycin can be given safely at biologically active doses with mild toxicity such as nausea, vomiting, diarrhea, and fatigue. Although single-agent studies have shown limited activity, combinations of tanespimycin with bortezomib or trastuzumab have suggested promising avenues of further evaluation in multiple myeloma and breast cancer, respectively.

CONCLUSIONS

Further development of HSP90-targeted strategies include testing of novel chemical structures having better solubility and stability and the potential for oral administration. Targeting of HSP90 in combination with other heat shock proteins, such as HSP70 or HSP27, may be an alternative strategy that warrants further exploration.

Phase I trial of daily oral Polyphenon E in patients with asymptomatic Rai stage 0 to II chronic lymphocytic leukemia

PURPOSE

To define the optimal dose of Polyphenon E for chronic daily administration and tolerability in patients with chronic lymphocytic leukemia (CLL).

PATIENTS AND METHODS

Previously untreated patients with asymptomatic Rai stage 0 to II CLL were eligible for participation. Polyphenon E with a standardized dose of epigallocatechin-3-gallate (EGCG) was administered using the standard phase I design with three to six patients per dose level (range, 400 to 2,000 mg by mouth twice a day). Trough plasma EGCG levels were measured 1 month after initiation of therapy. Response was classified using the National Cancer Institute (NCI) Working Group (WG) Criteria.

RESULTS

Thirty-three eligible patients were accrued to dose levels 1 to 8. The maximum-tolerated dose was not reached. The most common adverse effects included transaminitis (33%, all grade 1), abdominal pain (30% grade 1, 0% grade 2, and 3% grade 3), and nausea (39% grade 1 and 9% grade 2). One patient experienced an NCI WG partial remission. Other signs of clinical activity were also observed, with 11 patients (33%) having a sustained > or = 20% reduction in absolute lymphocyte count (ALC) and 11 (92%) of 12 patients with palpable adenopathy experiencing at least a 50% reduction in the sum of the products of all nodal areas during treatment. Trough plasma EGCG levels after 1 month of treatment ranged from 2.9 to 3,974 ng/mL (median, 40.4 ng/mL).

CONCLUSION

Daily oral EGCG in the Polyphenon E preparation was well tolerated by CLL patients in this phase I trial. Declines in ALC and/or lymphadenopathy were observed in the majority of patients. A phase II trial to evaluate efficacy using 2,000 mg twice a day began in November 2007.

Phase II trial of pazopanib in progressive, metastatic, iodine-insensitive differentiated thyroid cancers

3521

Background: Systemic therapies have had little impact on the outcomes of patients with advanced differentiated thyroid cancers. Methods: A three-outcome one-stage Phase II trial was conducted to assess the anti-tumor activity and toxicities of the orally bioavailable VEGF/tyrosine kinase inhibitor pazopanib (800 mg daily) in patients with advanced and progressive radioiodine-insensitive differentiated thyroid cancers. Up to 2 prior therapies were allowed, with measurable disease required. Design: at the 0.10 significance level, there would be a 90% chance of detecting a RECIST response rate of >20% given a true response rate of >5%; with the regimen considered promising if >4 confirmed responses observed. Results: From February to November 2008, 32 patients (53% male) aged 23–79 years (median: 63 years) were enrolled. Common sites of metastases were: lung (100%), nodes (52%), and bone (39%). Measurement data are available for 26 patients, with the median number of cycles administered thus far 4 (range: 1–8, total: 101). Overall, therapy has been well tolerated. Six patients (23%) required dose reduction due to: grade 2+ ALT (3 pts), grade 3 mucositis (1 pt); grade 3 diarrhea and dehydration (1 pt), and grade 3 abdominal pain (1 pt.). Other serious toxicities included grade 3 colon perforation and grade 3 chest pain (1 pt). No thyroglobulin antibody (TGA) negative patient has become TGA positive, and 11 of 16 patients (69%) with initially elevated thyroglobulin levels experienced a decline in thyroglobulin of >50%. Five RECIST partial responses have been confirmed to date (19%). Two patients are alive with disease progression and another has died from disease progression. Conclusions: Pazopanib appears to have both a favorable toxicity profile and promising clinical activity in patients with advanced and progressive differentiated thyroid cancers. Supported in part by NCI CA15083 and CM62205.

No significant financial relationships to disclose.

Phase I/II trial of CCI 779 and bevacizumab in advanced renal cell carcinoma (RCC): Safety and activity in RTKI refractory RCC patients

5039

Background: Combined mTOR and VEGF blockade is a potentially promising and rational strategy for the treatment of advanced RCC. We previously reported the phase I safety and efficacy results of CCI 779 (C) +bevacizumab (B) n RTKI naïve stage IV RCC patients (pts) (J Clin Oncol. 2007;25[18S Suppl]:5034). We now report the interim results of the phase 2 study of C+B in RTKI refractory RCC patients. Methods: Design: Open label, phase I/II study of C+B in advanced RCC pts. Patients with measurable stage IV RCC with a component of clear/conventional cell type, performance status 0–2 and good organ function were eligible. Up to two prior treatment regimens were allowed (at least one prior RTKI). Phase II dose was C = 25 mg IV weekly and B = 10 mg/kg every 2 weeks repeated in 4 week cycles. The primary objective of the phase II portion was to assess the proportion of patients who were progression-free 6 months after study entry. Secondary objectives were assessment of response rates and toxicity. Accrual goal = 40 pts. Results: Thirty-five pts have been enrolled into the phase 2 portion to date with 4 pts ineligible. Twenty-five pts are evaluable for response assessment and 29 pts are evaluable for toxicity. Baseline characteristics (N: 35): M/F: 28/7; Number of met. sites: 1/2/3+: 15/9/11; prior nephrectomy: 31; Number of prior therapies: 1 = 29; 2 = 2. Most common (>5%) Gr 3–4 AEs (N = 29) included fatigue (6), hypercholesterolemia (2), hypertriglyceridemia (2), anorexia (2), rash (2), and anemia (2). Responses were: PR/SD/PD = 4 (16%)/18 (72%)/3 (12%). Median number of cycles administered was 4. Six month progression free rates will mature by may 2009. Conclusions: C+B combination at the recommended phase 2 doses is feasible and well tolerated. Clinical benefit rates (PR/SD) in RTKI refractory RCC patients (88%) are encouraging. Data on 6 month progression-free rates are expected to mature in 4/09. Updated data on safety, response rates, and 6-month progression free rates will be presented on all evaluable patients. Correlative studies on available plasma, serum and tumor samples for angiogenic and molecular biomarkers are underway. Supported by N01-CM62205, R21 CA 119545–02, and Commonwealth Foundation.

[Table: see text]

A phase II trial of 17-allylamino-17-demethoxygeldanamycin in patients with hormone-refractory metastatic prostate cancer

PURPOSE

17-Allylamino-17-demethoxygeldanamycin (17-AAG) is a benzoquinone ansamycin antibiotic with antiproliferative activity in several mouse xenograft models, including prostate cancer models. A two-stage phase II study was conducted to assess the activity and toxicity profile of 17-AAG administered to patients with metastatic, hormone-refractory prostate cancer.

EXPERIMENTAL DESIGN

Patients with at least one prior systemic therapy and a rising prostate-specific antigen (PSA) were eligible. Patients received 17-AAG at a dose of 300 mg/m2 i.v. weekly for 3 of 4 weeks. The primary objective was to assess the PSA response. Secondary objectives were to determine overall survival, to assess toxicity, and to measure interleukin-6, interleukin-8, and maspin levels and quality of life.

RESULTS

Fifteen eligible patients were enrolled. The median age was 68 years and the median PSA was 261 ng/mL. Patients received 17-AAG for a median number of two cycles. Severe adverse events included grade 3 fatigue (four patients), grade 3 lymphopenia (two patients), and grade 3 back pain (two patients). The median PSA progression-free survival was 1.8 months (95% confidence interval, 1.3-3.4 months). The 6-month overall survival was 71% (95% confidence interval, 52-100%).

CONCLUSIONS

17-AAG did not show any activity with regard to PSA response. Due to insufficient PSA response, enrollment was stopped at the end of first stage per study design. The most significant severe toxicity was grade 3 fatigue. Further evaluation of 17-AAG at a dose of 300 mg/m2 i.v. weekly as a single agent in patients with metastatic, hormone-refractory prostate cancer who received at least one prior systemic therapy is not warranted.

Evaluation of lapatinib and topotecan combination therapy: tissue culture, murine xenograft, and phase I clinical trial data

PURPOSE

Topotecan resistance can result from drug efflux by P-glycoprotein (Pgp) and breast cancer resistance protein (BCRP) as well as survival signals initiated by epidermal growth factor receptor family members. The present studies were done to determine the effect of combining topotecan and the dual epidermal growth factor receptor/HER2 inhibitor lapatinib in tissue culture, a murine xenograft model, and a phase I clinical trial.

EXPERIMENTAL DESIGN

The effects of lapatinib on topotecan accumulation and cytotoxicity in vitro were examined in paired cell lines lacking or expressing Pgp or BCRP. Antiproliferative effects of the combination were assessed in mice bearing HER2+ BT474 breast cancer xenografts. Based on tolerability in this preclinical model, 37 patients with advanced-stage cancers received escalating doses of lapatinib and topotecan in a phase I trial.

RESULTS

Lapatinib increased topotecan accumulation in BCRP- or Pgp-expressing cells in vitro, and the combination showed enhanced efficacy in HER2+ BT474 xenografts. In the phase I study, nausea, vomiting, diarrhea, and fatigue were dose limiting. The maximum tolerated doses were 1,250 mg/d lapatinib by mouth for 21 or 28 days with 3.2 mg/m2 topotecan i.v. on days 1, 8, and 15 of 28-day cycles. Pharmacokinetic analyses showed that combined drug administration resulted in decreased topotecan clearance consistent with transporter-mediated interactions. Seventeen (46%) patients had disease stabilization.

CONCLUSIONS

The lapatinib/topotecan combination is well tolerated and warrants further study.

Drug efflux by breast cancer resistance protein (BCRP) is a mechanism of resistance to the insulin-like growth factor receptor/insulin receptor inhibitor, BMS-536924

Abstract #2149

Background: Inhibitors of the insulin-like growth factor 1 receptor (IGF-1R) are currently undergoing clinical testing. Preclinical investigations have identified IGF-1 signaling as a key mechanism for breast cancer growth and resistance to clinically useful therapies, including tamoxifen and trastuzumab. Thus, agents targeting IGF-1R have promise in the treatment of breast cancer. Determining mechanisms that can confer resistance to these agents may aid their clinical development.
 Methods: To understand factors may be important in predicting sensitivity to targeting the IGF-1 signaling pathway, we developed a cell line (MCF-7R4) that is resistant to BMS-554417, a small molecule, dual-kinase inhibitor of IGF-1R and insulin receptor (InsR). Compared with the parental MCF-7 cells, MCF-7R4 cells are 40- to 50-fold resistant to BMS-554417 and cross-resistant to the similar compound BMS-536924. The expression profiles of MCF-7R4 and that of MCF-7 were compared using Affymetrix GeneChip Human Genome U133 Plus 2.0 Arrays. Intracellular concentrations of BMS-536924 were examined by reverse phase high performance liquid chromatography. BMS-536924 cellular accumulation in vitro was visualized by fluorescence microscopy using a DAPI filter set. MCF-7 cells stably transfected with either the empty mammalian expression vector pcDNA (MCF-EV) or full length BCRP (MCF-BCRP) were examined for sensitivity to BMS 536924 by MTS assays.
 Results: Compared to MCF-7 cells, BCRP expression was increased 9-fold in MCF-7R4, which was highly statistically significant by t-test (p= 7.13E-09). Little change was observed in other ABC transporter proteins, including ABCB1. No change was observed in IGF-1R or InsR expression. BCRP overexpression in MCF-7R4 cells was confirmed by western blotting. MCF-7R4 cells had significantly lower intracellular accumulation of BMS-536924 compared to MCF-7 cells. Confirming these results, MCF-BCRP cells were significantly less sensitive to the cytoxic effects of BMS-536924 cells than MCF-EV cells.
 Conclusions: BCRP expression was stimulated by prolonged exposure of MCF-7 cells to BMS-554417. Upregulation of BCRP is one of the most significant changes observed in MCF-7R4 cells in comparison to parental cells. BCRP expression decreased cellular exposure to BMS-536924 and was sufficient to confer resistance. These data suggest that BSM-536924 is a substrate for BCRP-mediated efflux. Expression of BCRP may be important in de novo and acquired resistance to benzimidazole –based inhibitors of IGF-1R/InsR. Supported in part by the Mayo Clinic Breast SPORE (CA116201-03), NIH K12 (CA090628-05) and the Mayo Clinic Cancer Center (CA15083).

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2149.

Cisplatin abrogates the geldanamycin-induced heat shock response

Benzoquinone ansamycin antibiotics such as geldanamycin (GA) bind to the NH(2)-terminal ATP-binding domain of heat shock protein (Hsp) 90 and inhibit its chaperone functions. Despite in vitro and in vivo studies indicating promising antitumor activity, derivatives of GA, including 17-allylaminogeldanamycin (17-AAG), have shown little clinical efficacy as single agents. Thus, combination studies of 17-AAG and several cancer chemotherapeutics, including cisplatin (CDDP), have begun. In colony-forming assays, the combination of CDDP and GA or 17-AAG was synergistic and caused increased apoptosis compared with each agent alone. One measurable response that results from treatment with Hsp90-targeted agents is the induction of a heat shock factor-1 (HSF-1) heat shock response. Treatment with GA + CDDP revealed that CDDP suppresses up-regulation of HSF-1 transcription, causing decreased levels of stress-inducible proteins such as Hsp27 and Hsp70. However, CDDP treatment did not prevent trimerization and nuclear localization of HSF-1 but inhibited DNA binding of HSF-1 as shown by chromatin immunoprecipitation. Melphalan, but not camptothecin, caused similar inhibition of GA-induced HSF-1-mediated Hsp70 up-regulation. 3-(4,5-Dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium salt cell survival assays revealed that deletion of Hsp70 caused increased sensitivity to GA (Hsp70(+/+) IC(50) = 63.7 +/- 14.9 nmol/L and Hsp70(-/-) IC(50) = 4.3 +/- 2.9 nmol/L), which confirmed that a stress response plays a critical role in decreasing GA sensitivity. Our results suggest that the synergy of GA + CDDP is due, in part, to CDDP-mediated abrogation of the heat shock response through inhibition of HSF-1 activity. Clinical modulation of the HSF-1-mediated heat shock response may enhance the efficacy of Hsp90-directed therapy.

P-Glycoprotein-mediated resistance to Hsp90-directed therapy is eclipsed by the heat shock response

Despite studies that show the antitumor activity of Hsp90 inhibitors, such as geldanamycin (GA) and its derivative 17-allylamino-demethoxygeldanamycin (17-AAG), recent reports indicate that these inhibitors lack significant single-agent clinical activity. Resistance to Hsp90 inhibitors has been previously linked to expression of P-glycoprotein (P-gp) and the multidrug resistant (MDR) phenotype. However, the stress response induced by GA treatment can also cause resistance to Hsp90-targeted therapy. Therefore, we chose to further investigate the relative importance of P-gp and the stress response in 17-AAG resistance. Colony-forming assays revealed that high expression of P-gp could increase the 17-AAG IC(50) 6-fold in cells transfected with P-gp compared with parent cells. A549 cells selected for resistance to GA overexpressed P-gp, but verapamil did not reverse the resistance. These cells also overexpressed Hsp27, and Hsp70 was induced with 17-AAG treatment. When the GA and 17-AAG resistant cells were transfected with Hsp27 and/or Hsp70 small interfering RNA (siRNA), the 17-AAG IC(50) decreased 10-fold compared with control transfected cells. Transfection with siRNA directed against Hsp27, Hsp70, or Hsp27 and Hsp70 also increased sensitivity to EC78, a purine scaffold-based Hsp90 inhibitor that is not a P-gp substrate. We conclude that P-gp may contribute, in part, to resistance to 17-AAG, but induction of stress response proteins, such as Hsp27 and Hsp70, by Hsp90-targeted therapy plays a larger role. Taken together, our results indicate that targeting of Hsp27 and Hsp70 should be exploited to increase the clinical efficacy of Hsp90-directed therapy.

A phase I study of EKB-569 in combination with capecitabine in patients with advanced colorectal cancer

PURPOSE

To determine the maximum tolerated dose (MTD), characterize the principal toxicities, and assess the pharmacokinetics of EKB-569, an oral selective irreversible inhibitor of the epidermal growth factor receptor tyrosine kinase, in combination with capecitabine in patients with advanced colorectal cancer.

EXPERIMENTAL DESIGN

Patients were treated with EKB-569 daily for 21 days and capecitabine twice daily for 14 days of a 21-day cycle. The dose levels of EKB-569 (mg/day) and capecitabine (mg/m(2) twice daily) assessed were 25/750, 50/750, 50/1,000 and 75/1,000. An expanded cohort was enrolled at the MTD to better study toxicity and efficacy. Samples of plasma were collected to characterize the pharmacokinetics of the agents. Treatment efficacy was assessed every other cycle.

RESULTS

A total of 37 patients, the majority of whom had prior chemotherapy, received a total of 163 cycles of treatment. Twenty patients were treated at the MTD, 50 mg EKB-569, daily and 1,000 mg/m(2) capecitabine twice daily. Dose-limiting toxicities were diarrhea and rash. No patients had complete or partial responses but 48% had stable disease. The conversion of capecitabine to 5-fluorouracil was higher for the combination of EKB-569 and capecitabine (321+/-151 ng*h/mL) than for capecitabine alone (176+/-62 ng*hours/mL; P=0.0037).

CONCLUSION

In advanced colorectal cancer, 50 mg EKB-569 daily can be safely combined with 1,000 mg/m(2) capecitabine twice a day. A statistically significant increase in plasma levels of 5-fluorouracil for the combination of EKB-569 and capecitabine may be due to the single-dose versus multiple-dose exposure difference, variability in exposure or a potential drug interaction.

HER receptor signaling confers resistance to the insulin-like growth factor-I receptor inhibitor, BMS-536924

We have reported previously the activity of the insulin-like growth factor-I (IGF-IR)/insulin receptor (InsR) inhibitor, BMS-554417, in breast and ovarian cancer cell lines. Further studies indicated treatment of OV202 ovarian cancer cells with BMS-554417 increased phosphorylation of HER-2. In addition, treatment with the pan-HER inhibitor, BMS-599626, resulted in increased phosphorylation of IGF-IR, suggesting a reciprocal cross-talk mechanism. In a panel of five ovarian cancer cell lines, simultaneous treatment with the IGF-IR/InsR inhibitor, BMS-536924 and BMS-599626, resulted in a synergistic antiproliferative effect. Furthermore, combination therapy decreased AKT and extracellular signal-regulated kinase activation and increased biochemical and nuclear morphologic changes consistent with apoptosis compared with either agent alone. In response to treatment with BMS-536924, increased expression and activation of various members of the HER family of receptors were seen in all five ovarian cancer cell lines, suggesting that inhibition of IGF-IR/InsR results in adaptive up-regulation of the HER pathway. Using MCF-7 breast cancer cell variants that overexpressed HER-1 or HER-2, we then tested the hypothesis that HER receptor expression is sufficient to confer resistance to IGF-IR-targeted therapy. In the presence of activating ligands epidermal growth factor or heregulin, respectively, MCF-7 cells expressing HER-1 or HER-2 were resistant to BMS-536924 as determined in a proliferation and clonogenic assay. These data suggested that simultaneous treatment with inhibitors of the IGF-I and HER family of receptors may be an effective strategy for clinical investigations of IGF-IR inhibitors in breast and ovarian cancer and that targeting HER-1 and HER-2 may overcome clinical resistance to IGF-IR inhibitors.

Medical management of pancreatic neuroendocrine tumors

BACKGROUND

Pancreatic neuroendocrine tumors (PNET) are rare malignancies frequently diagnosed at a late stage, with symptoms related to bulky disease. Hormonal secretion, when responsible for symptoms, permits, on the other hand, early diagnosis of the disease. Surgery remains the cornerstone of therapeutic management. However, due to advanced disease, many patients are not candidates for aggressive surgical therapy. Tumor growth control and symptom management are thus achieved through medical approaches, including somatostatin (SST) analogs, chemotherapy, interferon, and more recently, targeted therapy. The purpose of this review is to collect, examine, and analyze data available in the literature regarding contemporary therapeutic management of PNET, with emphasis on medical approaches. It also offers perspectives on the future of molecular targeted therapies in these neoplasms. However, we point out that much of the literature published to date includes noncomparative studies (mainly phase II studies), leading to thorny interpretation of the results.

METHODS

A systematic search of all the literature in English regarding PNET was performed, based on a MEDLINE search (Pubmed) carried out from January 1970 to May 2005.

RESULTS

Approximately 40 trials, including over 1,000 patients, have been retrieved from our MEDLINE search. SST analogs and interferon therapies do allow control over hormone secretion and subsequent symptoms in the majority of treated subjects, but offer a poor tumor growth control rate. Chemotherapies, although more efficient in reducing tumor burden, are often toxic. New approaches such as immunotherapy and targeted therapies are still under investigation.

CONCLUSIONS

Whether alone or in combination with surgery, conventional medical therapies represent a crucial aspect of PNET management. Hopefully, in the near future, a new era of antitumoral agents, such as targeted therapies, will strengthen our therapeutic arsenal, either alone or combined with other therapies.

Phase II trial of oxaliplatin/irinotecan/5-fluorouracil/leucovorin for metastatic colorectal cancer

BACKGROUND

Individually, oxaliplatin and irinotecan have substantial activity in metastatic colorectal cancer (CRC) in combination with 5-fluorouracil/leucovorin. A combination regimen using all 4 agents could potentially increase response rates in CRC.

PATIENTS AND METHODS

A multicenter phase II trial of oxaliplatin 85 mg/m(2) on day 1, irinotecan 175 mg/m(2) on day 1, 5-fluorouracil 240 mg/m(2) by 90-minute infusion on days 2-5, and leucovorin 20 mg/m(2) on days 2-5 of a 21-day cycle was undertaken in patients with CRC through the North Central Cancer Treatment Group. The primary endpoint was response rate, with secondary endpoints of toxicity and quality of life.

RESULTS

Of 14 patients enrolled (13 evaluable), 3 partial responses were seen (23%; 95% confidence interval, 5%-54%), and 9 patients had stable disease (69%). Toxicity was significant, with 1 (8%) grade 5 event (diarrhea and dehydration) and 3 (23%) grade 4 events (leukopenia and diarrhea). The study was closed to further enrollment because of toxicity.

CONCLUSION

The 4-drug regimen was extremely toxic. Future studies incorporating irinotecan- and oxaliplatin-based therapy should consider alternative schedules.

A phase II trial of tipifarnib in myelofibrosis: primary, post-polycythemia vera and post-essential thrombocythemia

Patients with primary myelofibrosis (PMF) or post-polycythemia vera or post-essential thrombocythemia myelofibrosis (post-PV/ET MF) have limited therapeutic options. The farnesyltransferase-inhibitor tipifarnib inhibits in vitro proliferation of myeloid progenitors from such patients. In the current phase II clinical trial, single-agent oral tipifarnib (300 mg twice daily x 21 of 28 days) was given to 34 symptomatic patients with either PMF (n=28) or post-PV/ET MF (n=6). Median time to discontinuation of protocol therapy was 4.6 months; reasons for early termination (n=19; 56%) included disease progression (21%) and adverse drug effects (18%). Toxicities (>/=grade 3) included myelosuppression (n=16), neuropathy (n=2), fatigue (n=1), rash (n=1) and hyponatremia (n=1). Response rate was 33% for hepatosplenomegaly and 38% for transfusion-requiring anemia. No favorable changes occurred in bone marrow fibrosis, angiogenesis or cytogenetic status. Pre- and post-treatment patient sample analysis for in vitro myeloid colony growth revealed substantial reduction in the latter. Clinical response did not correlate with either degree of colony growth, measurable decrease in quantitative JAK2(V617F) levels or tipifarnib IC(50) values (median 11.8 nM) seen in pretreatment samples. The current study indicates both in vitro and in vivo tipifarnib activity in PMF and post-PV/ET MF.

MC044h, a phase II trial of sorafenib in patients (pts) with metastatic neuroendocrine tumors (NET): A Phase II Consortium (P2C) study

4504

Background: Treatment options for metastatic NET, including islet cell carcinoma (ICC) and carcinoid tumor (CT), are limited. These tumors frequently express vascular endothelial growth factor receptor-2 (VEGFR-2) and platelet derived growth factor receptor receptor-β (PDGFR-β). Sorafenib, a small-molecule inhibitor of the VEGFR-2 and PDGFR-β tyrosine kinase domains, is a rational targeted therapy to evaluate in NET. Methods: Eligibility criteria included: ECOG PS = 2, = 1 prior chemotherapy, good organ function and signed informed consent. Prior interferon and prior or concurrent octreotide at a stable dose were allowed. Pts unable to take oral medications, with uncontrolled hypertension or with symptomatic coronary artery disease were excluded. Pts received sorafenib 400 mg po BID. Primary endpoint was response by RECIST in two cohorts (ie, CT and ICC) using separate 2-stage phase II designs. Results: 93 pts were enrolled: (50 CT, 43 ICC). For pts evaluable for the primary endpoint, 4 of 41 (10%) CT pts and 4 of 41 (10%) ICC pts had a PR. There were 3 minor responses (MR = 20–29% decrease in sum of target lesion diameters) in CT pts and 9 MRs in ICC pts for PR+MR rate of 17% for CT pts and 32% for ICC pts. For pts evaluable, 6-month progression-free survival was observed in 8/20 CT and 14/23 ICC pts. Grade 3–4 toxicity occurred in 43% of pts, with skin (20%), GI (7%) and fatigue (9%) most common. Translational studies from tumor tissue will be presented. Conclusions: Sorafenib at 400 mg po BID has modest activity in metastatic neuroendocrine tumors, with frequent grade = 3 toxicity. Supported by NOI CM6225.

No significant financial relationships to disclose.

A phase I study of lapatinib and topotecan in patients with solid tumors

3598

Background: Drug resistance to topotecan can be the result of BCRP/ABCG2 expression. BCRP is a member of the ABC transporter family that pumps anticancer drugs out of the cell. Lapatinib is a potent and selective dual inhibitor of epidermal growth factor receptor (EGFR or ErbB1) and ErbB2 (Her2/Neu). 4-aminoquinazoline tyrosine kinase inhibitors have been shown to enhance the cytotoxicity of topotecan through inhibition of BCRP-mediated drug efflux in cancer cells. Methods: Thirty-seven patients with advanced stage cancers were enrolled at escalating dose levels of lapatinib and topotecan in cohorts IA, IB and IIB (MTD). Treatment schedule included lapatinib (750 - 1500 mg/d) daily for 21 (cohort IA) or 28 days (cohort IB) and topotecan (2.4 - 4.0 mg/ m2), days 1, 8 and 15; cycles were repeated every 28 days. Three patients were treated at each dose level, 18 on cohort IA, 9 on cohort IB and 10 at MTD (cohort IIB). Assessments of toxicity were performed with each cycle and clinical response was determined per RECIST criteria every other cycle. Results: The MTD for cohorts IA and IB was reached at a dose of 1250 mg of lapatinib and 3.2 mg/m2 of IV topotecan on days 1, 8 and 15. No DLT were seen during the dose escalation stage of cohorts IA and IB. Ten patients were enrolled at the MTD. There were no grade 4+ events. Thirteen grade 3+ events, considered to be related to treatment, were seen in 6 patients. The most common grade 3+ toxicities included dehydration (2) diarrhea (2), nausea (3), vomiting (2), neutropenia (1), thrombocytopenia (1), and fatigue (1). No abnormalities in left ventricular ejection fraction were noted. Stable disease was seen in 46% of the 37 patients. Conclusions: The combination of lapatinib and topotecan is a well-tolerated regimen. The MTD for the combination is lapatinib 1,250 mg orally once daily for 21 or 28 days and topotecan 3.2 mg/m2 on days 1, 8 and 15. Pharmacokinetic analysis for drug interaction will be available for presentation at the meeting. Supported in part by GSK and Mayo Clinic

No significant financial relationships to disclose.

Phase I/II trial of CCI-779 and bevacizumab in stage IV renal cell carcinoma: Phase I safety and activity results

5034

Background: The mammalian target of rapamicin (mTOR) and vascular endothelial growth factor (VEGF) pathways are critically involved in the pathogenesis and progression of clear cell renal cell carcinoma. Methods: The goal of the phase I portion of the trial was to determine the maximum tolerated dose (MTD) and dose limiting toxicity (DLT) of the combination of the mTOR inhibitor CCI-779 (C) and the anti-VEGF monoclonal antibody Bevacizumab (B). Patients with measurable stage IV clear cell RCC, performance status 0–2 and good organ function were eligible. Up to two prior treatment regimens were allowed. Treatment consisted of 25 mg IV weekly C and escalating IV doses of B (level 1= 5 mg/kg; level 2= 10 mg/kg) every other week. A cycle was defined as 4 weeks. Results: A total of 10 male and 2 female patients, median age 66 yrs (50–77) were enrolled to the phase I portion of the trial. PS: 0/1= 6/6; prior nephrectomy = 10; prior systemic therapy = 7 (prior cytokine therapy = 6); Number of metastatic sites: 1/2/≥3 = 2/2/8; one patient (out of 6) in dose level 1 experienced DLT which consisted of grade 3 hypertriglyceridemia. 1/6 patient in dose level 2 experienced DLT with grade 3 mucositis. Other grade 3 toxicities that were not DLTs included hypertension, proteinuria, hemorrhage, nausea/vomiting, dehydration, anorexia, pneumonitis, anemia, and hypophosphatemia. The best responses in the 12 evaluable patients included 7 PRs and 3 SDs. One patient had PD due to symptomatic deterioration and in one patient response information is not available at the time of this submission. Conclusions: Combination therapy with CCI-779 and Bevacizumab is safe and shows promising clinical antitumor activity. The recommended phase II dose is CCI-779 25 mg/week with bevacizumab 10 mg/kg every other week. The phase II study in stage IV renal cell cancer patients refractory to FDA approved receptor tyrosine kinase inhibitors is under way. The goals of the phase II portion are to determine the proportion of patients who have not had disease progression at 6 months, safety, response rates and correlative biomarker studies including determination of the tumor’s VHL-HIF-VEGF status, PTEN/AKT expression, plasma angiogenic activity and angiogenic cytokines. Supported by NCI N01-CM-62205

No significant financial relationships to disclose.

Oxaliplatin in the treatment of colorectal cancer

Significant advances in the treatment of colorectal cancer have been observed over the past several years. With the introduction of oxaliplatin combined with infusional 5-fluorouracil and leucovorin, survival for patients with metastatic colorectal cancer has nearly doubled. The incorporation of biologic agents that target angiogenesis (bevacizumab) and tumor growth pathways (cetuximab, panitumimab) extends survival even further, in addition to increasing response rates in patients with metastatic disease. The benefit of these newer drugs is also being realized in the adjuvant setting, where the addition of oxaliplatin to infusional 5-fluorouracil and leucovorin has led to improvements in 3-year disease-free survival. Future challenges with the use of oxaliplatin include defining strategies to optimize its use while avoiding treatment-limiting neurotoxicity and identification of markers predictive of response.

A phase I clinical and pharmacokinetic study of CS-682 administered orally in advanced malignant solid tumors

CS-682 (1-(2-C-cyano-2-deoxy-beta-D-arabino-pentofuranosyl)-N4-palmitoylcytosine) is a novel orally administered 2'-deoxycytidine-type antimetabolite, which has a wide spectrum of antitumor activity in human tumor xenograft models. We conducted a phase I study to define the toxicity, pharmacokinetics and antitumor activity of CS-682 in patients with advanced solid tumors. Forty patients were enrolled to receive escalating doses of CS-682. CS-682 was given orally, once daily three times a week (Monday, Wednesday and Friday), for four weeks consecutively, followed by a two-week rest period. Twenty-two men and 18 women, median age 63.5 (range 31 to 82) were treated. The most common tumor type was colorectal cancer with 15 patients. Others tumors occurring in 3 or more patients included prostate, breast and lung carcinomas. Sixty percent of the patients had received greater than 2 prior chemotherapy programs. Patients have been treated at each of the following dose levels (mg/m2/day): 1.5, 12, 20, 25, 30, 50, 67, 90, 120, 160 and 220. Non hematologic toxicities grade 3 [NCI Common Toxicity Criteria (version 2.0)] related to treatment included nausea in 2, vomiting in 1, anorexia and asthenia in 2, and dehydration in 1. Severe hematologic toxicities (grade 3-4) were seen more frequently with 10 patients experiencing grade 3-4 neutropenia, 2 with grade 4 thrombocytopenia and 2 with grade 3 anemia. Neutropenia requiring hospitalization occurred in 3 patients. Dose-limiting neutropenia was observed at 220 mg/m2/day. The maximum tolerated dose was determined to be 160 mg/m2/day. No tumor responses were observed in this study. Six patients experienced stable disease, including one who has stable disease after having received 34 courses of CS-682. After oral administration, CS-682 is rapidly absorbed and metabolized to CNDAC, which is further metabolized by cytidine deaminase to the inactive product CNDAU. Peak plasma concentrations of CNDAC were achieved 2.2 +/- 0.9 h after drug administration and the terminal elimination half-life was 1.7 +/- 1.5 h. Measurable concentrations of CNDAU were first seen 0.60 +/- 0.31 h, peak plasma concentrations were achieved 3.1 +/- 0.9 h after the CS-682 dose, and the terminal elimination half-life was 2.3 +/- 1.7 h. The recommended phase 2 starting dose for the 3 days/week regimen of CS-682 is 160 mg/m2/day for 4 weeks repeated after a 2-week rest period.

A limited sample model to predict area under the drug concentration curve for 17-(allylamino)-17-demethoxygeldanamycin and its active metabolite 17-(amino)-17-demethoxygeldanomycin

PURPOSE

The Hsp90-directed anticancer agent 17-(allylamino)-17-demethoxygeldanamycin (17-AAG) is currently undergoing phase I and phase II clinical investigation. Our goal was to develop a simple limited sampling model (LSM) for AUC of 17-AAG and its active metabolite, 17-(amino)-17-demethoxygeldanomycin (17-AG) using drug concentrations from a few time points.

METHODS

Pharmacokinetic data from 34 patients treated at 11 dose levels on a Mayo Clinic Cancer Center phase I clinical trial of 17-AAG was utilized. Blood samples were collected at 11 different time points, spanning 25 h. Graphical methods and correlations were used to assess functional forms and univariate relationships. Multivariate linear regression and bootstrap resampling were used to develop the LSM.

RESULTS

Using log-transformed data, the two and three time point 17-AAG LSMs are log-AUC (17-AAG) = 0.869 + 0.653*(C(55min)) +0.469*(C(5h)) and log-AUC (17-AAG) = 2.449 + 0.400*(C(55min)) +0.441*(C(5h)) +0.142*(C(9h)). The two and three time point LSMs for 17-AG are log-AUC (17-AG) = 3.590 + 0.747*(C(5h)) +0.169*(C(17h)), and log-AUC (17-AG) = 3.797 + 0.650*(C(5h)) +0.111*(C(9h)) +0.122*(C(17h)). Ninety-seven percent and 94% of the predicted log-AUC values were within 5% of the observed log-AUC for the two and three time point models for 17-AAG and 17-AG respectively.

CONCLUSIONS

The precise calculation of AUC is cumbersome and expensive in terms of patient and clinical resources. The LSM developed using a multivariate regression approach is clinically and statistically meaningful. Prospective validation is underway.

Association of DNA methylation and epigenetic inactivation of RASSF1A and beta-catenin with metastasis in small bowel carcinoid tumors

We analyzed promoter methylation of RASSF1A, CTNNB1, CDH1, LAMB3, LAMC2, RUNX3, NORE1A, and CAV1 using methylation-specific PCR in 33 cases of small bowel carcinoid with both matched primary and metastatic tumors. The methylation status of RASSF1A and CTNNB1 were also determined in six primary appendiceal carcinoid tumors. Two neuroendocrine cell lines, NCI-H727 and HTB-119, were analyzed for promoter methylation. Immunohistochemical analyses for RASSF1A and beta-catenin were performed in 28 matched primary and metastatic tumors. Western blot analysis for RASSF1A and beta-catenin was also performed. Normal enterochromaffin cells were unmethylated in all eight genes examined. RASSF1A and CTNNB1 were unmethylated in appendiceal carcinoids. Methylation of RASSF1A and CTNNB1 promoters was more frequent in metastatic compared to primary tumors (p = 0.013 and 0.004, respectively). The NCI-H727 and HTB-119 cells lines were methylated in the RASSF1A promoter region, and after treatment with 5-aza-2'-deoxycytidine (5-AZA), RASSF1A mRNA was expressed in both cell lines. Western blot results for RASSF1A and beta-catenin supported the methylation-specific PCR findings. The other six genes did not show significant differences. These results suggest that increased methylation of RASSF1A and CTNNB1 may play important roles in progression and metastasis of small bowel carcinoid tumors.

Up-regulation of Heat Shock Protein 27 Induces Resistance to 17-Allylamino-Demethoxygeldanamycin through a Glutathione-Mediated Mechanism

17-Allylamino-demethoxygeldanamycin (17-AAG), currently in phase I and II clinical trials as an anticancer agent, binds to the ATP pocket of heat shock protein (Hsp90). This binding induces a cellular stress response that up-regulates many proteins including Hsp27, a member of the small heat shock protein family that has cytoprotective roles, including chaperoning of cellular proteins, regulation of apoptotic signaling, and modulation of oxidative stress. Therefore, we hypothesized that Hsp27 expression may affect cancer cell sensitivity to 17-AAG. In colony-forming assays, overexpression of Hsp27 increased cell resistance to 17-AAG whereas down-regulation of Hsp27 by siRNA increased sensitivity. Because Hsp27 is known to modulate levels of glutathione (GSH), we examined cellular levels of GSH and found that it was decreased in cells transfected with Hsp27 siRNA when compared with control siRNA. Treatment with buthionine sulfoximine, an inhibitor of GSH synthesis, also sensitized cells to 17-AAG. Conversely, treatment of Hsp27 siRNA-transfected cells with N-acetylcysteine, an antioxidant and GSH precursor, reversed their sensitivity to 17-AAG. A cell line selected for stable resistance to geldanamycin relative to parent cells showed increased Hsp27 expression. When these geldanamycin- and 17-AAG-resistant cells were transfected with Hsp27 siRNA, 17-AAG resistance was dramatically diminished. Our results suggest that Hsp27 up-regulation has a significant role in 17-AAG resistance, which may be mediated in part through GSH regulation. Clinical modulation of GSH may therefore enhance the efficacy of Hsp90-directed therapy.

Randomized phase II study of interleukin-12 in combination with rituximab in previously treated non-Hodgkin's lymphoma patients

PURPOSE

Rituximab is a chimeric antibody that induces B-cell apoptosis and recruits immune effector cells to mediate cell lysis. Interleukin-12 (IL-12) facilitates cytolytic responses by T cells and natural killer cells. This phase II study was done to determine the efficacy and toxicity of IL-12 in combination with rituximab in patients with B-cell non-Hodgkin's lymphoma (NHL).

EXPERIMENTAL DESIGN

Fifty-eight patients with histologically confirmed relapsed B-cell NHL were randomized to receive concurrent treatment with rituximab and IL-12 (arm A) or rituximab with subsequent treatment with IL-12 after documented nonresponse or progression after rituximab (arm B). Treatment consisted of 375 mg/m2 rituximab on days 1, 8, 15, and 22 and 300 ng/kg IL-12 given s.c. twice weekly starting on day 2 for arm A or upon progression for arm B.

RESULTS

The overall response rate was 37% (11 of 30) in arm A and 52% (13 of 25) in arm B. All of the responses seen in arm B occurred while patients received rituximab, and no responses occurred during treatment with subsequent IL-12. The median duration of response was 16 months for arm A and 12 months for arm B. Biopsy specimens were serially obtained in a subset of patients and showed that changes in gene expression were different when cells from the peripheral blood were compared with cells from lymph node biopsies.

CONCLUSIONS

The concomitant use of IL-12 and rituximab had modest disease activity in patients with B-cell NHL, but the sequential administration of IL-12 after rituximab did not result in additional clinical responses.

A phase I and pharmacokinetic study of temsirolimus (CCI-779) administered intravenously daily for 5 days every 2 weeks to patients with advanced cancer

PURPOSE

Patients with advanced cancer received temsirolimus (Torisel, CCI-779), a novel inhibitor of mammalian target of rapamycin, i.v. once daily for 5 days every 2 weeks to determine the maximum tolerated dose, toxicity profile, pharmacokinetics, and preliminary antitumor efficacy.

EXPERIMENTAL DESIGN

Doses were escalated in successive cohorts of patients using a conventional phase I clinical trial design. Samples of whole blood and plasma were collected to determine the pharmacokinetics of temsirolimus and sirolimus, its principal metabolite.

RESULTS

Sixty-three patients were treated with temsirolimus (0.75-24 mg/m(2)/d). The most common drug-related toxicities were asthenia, mucositis, nausea, and cutaneous toxicity. The maximum tolerated dose was 15 mg/m(2)/d for patients with extensive prior treatment because, in the 19 mg/m(2)/d cohort, two patients had dose-limiting toxicities (one with grade 3 vomiting, diarrhea, and asthenia and one with elevated transaminases) and three patients required dose reductions. For minimally pretreated patients, in the 24 mg/m(2)/d cohort, one patient developed a dose-limiting toxicity of grade 3 stomatitis and two patients required dose reductions, establishing 19 mg/m(2)/d as the maximum acceptable dose. Immunologic studies did not show any consistent trend toward immunosuppression. Temsirolimus exposure increased with dose in a less than proportional manner. Terminal half-life was 13 to 25 hours. Sirolimus-to-temsirolimus exposure ratios were 0.6 to 1.8. A patient with non-small cell lung cancer achieved a confirmed partial response, which lasted for 12.7 months. Three patients had unconfirmed partial responses; two patients had stable disease for >/=24 weeks.

CONCLUSION

Temsirolimus was generally well tolerated on this intermittent schedule. Encouraging preliminary antitumor activity was observed.

A Phase I Trial of Twice-Weekly 17-Allylamino-Demethoxy-Geldanamycin in Patients with Advanced Cancer

PURPOSE

To determine the maximum tolerated dose (MTD), dose-limiting toxicity, and pharmacokinetics of 17-allylamino-demethoxy-geldanamycin (17-AAG) administered on days 1, 4, 8, and 11 every 21 days and to examine the effect of 17-AAG on the levels of chaperone and client proteins.

EXPERIMENTAL DESIGN

A phase I dose escalating trial in patients with advanced solid tumors was done. Toxicity and tumor responses were evaluated by standard criteria. Pharmacokinetics were done and level of target proteins was measured at various points during cycle one.

RESULTS

Thirteen patients were enrolled in the study. MTD was defined as 220 mg/m2. Dose-limiting toxicities were as follows: dehydration, diarrhea, hyperglycemia, and liver toxicity. At the MTD, the mean clearance of 17-AAG was 18.7 L/h/m2. There was a significant decrease in integrin-linked kinase at 6 hours after infusion on day 1 but not at 25 hours in peripheral blood mononuclear cells. Treatment with 17-AAG on day 1 significantly increased pretreatment levels of heat shock protein (HSP) 70 on day 4, which is consistent with the induction of a stress response. In vitro induction of a stress response and up-regulation of HSP70 resulted in an increased resistance to HSP90-targeted therapy in A549 cells.

CONCLUSIONS

The MTD of 17-AAG on a twice-weekly schedule was 220 mg/m2. Treatment at this dose level resulted in significant changes of target proteins and also resulted in a prolonged increase in HSP70. This raises the possibility that HSP70 induction as part of the stress response may contribute to resistance to 17-AAG.

Phase II study of erlotinib in patients with advanced biliary cancer

PURPOSE

Epidermal growth factor receptor/human epidermal growth factor receptor 1 and ligand expression is common in biliary cancers (BILI) and may be associated with worse outcome. The primary objective of this study was to determine the proportion of patients with advanced BILI who were progression-free at 6 months.

METHODS

Patients with either unresectable or metastatic disease were studied. Only one prior systemic or locoregional therapy was allowed. Erlotinib was administered continuously at a dose of 150 mg per day orally.

RESULTS

Forty-two patients with BILI were enrolled. The median age was 67 years (range, 33 to 82 years). Fifty-two percent of patients had Eastern Cooperative Oncology Group performance status of 1. Fifty-seven percent of patients had received prior chemotherapy for advanced BILI. HER1/EGFR expression by immunohistochemistry in tumor cells was detected in 29 (81%) of the 36 assessable patients. Seven of the patients (17%; 95% CI, 7% to 31%) were progression free at 6 months. Three patients had partial response by Response Evaluation Criteria in Solid Tumors Group classification of duration 4, 4, and 14 months, respectively. All responding patients had mild (grade 1/2) skin rash and two patients had positive tumoral HER1/EGFR expression. Three patients (7%) had toxicity-related dose reductions of erlotinib due to grade 2/3 skin rash.

CONCLUSION

Results suggest a therapeutic benefit for EGFR blockade with erlotinib in patients with biliary cancer. Additional studies with erlotinib as a single agent and in combination with other targeted agents are warranted in this disease.

Phase I, pharmacokinetic (PK), & pharmacodynamic (PD) study of 17-dimethylaminoethylamino-17-demethoxygeldanamycin, (17DMAG, NSC 707545) in patients with advanced solid tumors

3021

Background: 17DMAG is a water-soluble analog of 17-allylamino-17-demethoxygeldanamycin (17AAG), the first geldanamycin compound to enter clinical trials. 17DMAG causes oncoprotein degradation by binding to heat shock protein 90 (HSP90) & has greater in-vitro activity than 17AAG. In animals treated with 17DMAG, liver toxicity is dose-limiting. The objectives of this first-in-human study are to: establish the dose-limiting toxicity (DLT); recommend a phase 2 dose; & characterize the PK & PD of 17DMAG. Methods: Using a modified accelerated schema, escalating doses of 17DMAG are given IV over 1 h daily x 5 (schedule A) or daily x 3 (schedule B) every 3 weeks. Plasma 17DMAG concentrations during cycle 1 are quantitated by LC/MS. HSP70 & ILK levels in peripheral mononuclear cells are measured by western blot at baseline & 24 h on d 1. Results: 37 pts have been enrolled. On schedule A, dose levels are 1.5, 3, 6, 9, 12 & 16 mg/m2/d (n = 20). On schedule B, the starting dose was 2.5 mg/m2/d. Based on safety information from schedule A, subsequent schedule B dose levels were 14, 19, 25 & 34 mg/m2/d (n = 17). One DLT was noted in schedule A (16 mg/m2) & consisted of reversible liver enzyme elevation. End-of-infusion (EOI) 17DMAG concentrations (33–2074 ng/ml) & AUC0–24 (200–5200 ng/ml x h) increase linearly with dose. Interpatient PK variability was substantial, with CV% of 16–59%. The daily administration schedule precluded precise definition of 17DMAG t1/2 & clearance, but estimates of t1/2 & clearance ranged from 10.8 to 77 h & 19–160 ml/min/m2, respectively. Between 0 & 24 h, 20.5 ± 8.6% (range 4–43.8%) of the administered dose was excreted in urine. HSP70 increased between 0.2 & 3.7 fold above baseline in PBMCs at 24 h at 12, 16, & 25 mg/m2. There is an indication of ILK degradation in 3 of 4 patients evaluated at 25 mg/m2. Conclusions: 17DMAG is well tolerated at current dose levels & maximal tolerated dose has not been reached. 17DMAG plasma PK are linear over the doses delivered to date, & there is evidence of a target effect as manifested by↑HSP70 & ↓ILK. Support: U01CA099168–01, U01CA62502, U01CA69912, R01CA90390 & NIH/NCCR/GCRC grants #5M01 RR 00056 & M01 RR00080

No significant financial relationships to disclose.

A phase II trial of gefitinib in patients (pts) with progressive metastatic neuroendocrine tumors (NET): A Phase II Consortium (P2C) study

4043

Background: Systemic treatment options for progressive metastatic NET, including islet cell carcinoma (ICC) and carcinoid tumor (CT), are limited. These tumors frequently express the epidermal growth factor receptor (EGFR). Gefitinib, a small-molecule inhibitor of the EGFR tyrosine kinase, has been shown to inhibit the growth of NET cell lines. Methods: Eligibility criteria included: radiographic progression by RECIST criteria, ECOG PS ≤ 2, ≤ 1 prior chemotherapy, and good organ function. Prior interferon and prior or concurrent octreotide (if disease progression documented on stable dose) were allowed. Pts received gefitinib 250 mg po daily. We evaluated 6 month (mos) progression-free survival (PFS) in two cohorts (ie, CT and ICC) using separate 2-stage phase II designs. 6 mos PFS rates of 30% (CT) and 10% (ICC) were considered promising. Results: 96 pts were enrolled: (57 CT, 39 ICC). For pts evaluable for the primary endpoint, 23 of 38 (61%) CT pts and 9 of 29 (31%) pts with ICC were progression-free at 6 mos. 1 PR and one minor response (MR = 20–29% decrease in sum of target lesion diameters) were observed in 40 CT pts; 2 PR and 1 MR in 31 ICC pts. In addition, 32% (12/38) of CT and 14% (4/29) of ICC pts had stable disease on study for a duration that exceeded by at least 4 months the time to progression documented prior to study entry. Grade 3–4 toxicity was infrequent with fatigue (6%), diarrhea (5%) and rash (3%) most common. Evaluation of markers of the EGFR pathway on tumor tissue will be presented. Conclusions: Gefitinib is well-tolerated and results in prolonged disease stabilization in pts with prior documented objective progression of CT and ICC, with rare objective responses. Supported by NOI CM17104.

No significant financial relationships to disclose.

A multicenter phase 2 consortium (P2C) study of triapine in patients (pts) with advanced adenocarcinoma of the pancreas

14118

Background: Triapine is a small molecule iron chelator that has been shown to inhibit ribonucleotide reductase (RR) at the M2 subunit. Early trials suggested activity in pancreatic cancer. The P2C initiated a study of single agent Triapine as both first-line therapy and for pts with gemcitabine-refractory disease. Correlatives included: pharmacokinetics, MDR polymorphisms, and the effects of Triapine on cell cycle and electron paramagnetic resonance spectroscopy (EPR). Methods: Standard eligibility criteria were used, however, pts with G6PD deficiency were excluded. Triapine was given 96 mg/m2 IV over 2 hours, days 1–4 and 15–18, repeated q 28 days. Primary goals - evaluate survival (S) at 6 mos (previously untreated pts) and 4 mos (refractory pts). Interim analyses were planned when 28 previously untreated and 20 refractory pts were enrolled. Results: 14 eligible pts were enrolled in 10 mos (13 refractory, 9 male). The previously untreated pt received only 1 cycle secondary to progressive disease. Of the 13 refractory pts, 7 pts received at most 2 cycles; 6 received 1. Disease progression precluded further treatment in 11 pts. 6 pts had Gr 4 toxicities at least possibly related to drug, including: neutropenia-4, hyperkalemia-1, hyponatremia-1, leukopenia-1, thrombocytopenia-1, hypophosphatemia-1. 6 pts had a Gr 3 fatigue. One refractory patient expired on study. No responses were seen. Estimated 4 mos S in refractory pts is 16% (95% CI 3–94). EPR studies showed that Triapine led to a loss of the RR tyrosine radical EPR signal. Conclusions: Enrollment was suspended due to excess toxicity and lack of activity in pts refractory to gemcitabine. Correlative studies confirm the mechanism of action of Triapine as a chelating agent on RR. Supported by NCI Grant N01 CM17104 and the NCI Translational Research Fund.

No significant financial relationships to disclose.

Phase I study of CNF1010 (lipid formulation of 17-(allylamino)-17-demethoxygeldanamycin: 17-AAG) in patients with advanced solid tumors

10062

Background: 17-AAG is a benzoquinone ansamycin that binds to and inhibits the HSP90 family of molecular chaperones leading to the proteasomal degradation of client proteins critical in malignant cell proliferation and survival. We have undertaken a Phase 1 trial of CNF1010, an oil-in-water nanoemulsion of 17-AAG. Methods: Patients (pts) with advanced solid tumors, ECOG PS 0–2, and adequate hematologic, hepatic, renal and cardiac functions received CNF1010 by 1 h intravenous infusion, twice-a-week, three weeks out of four, starting at 6 mg/m2 per dose. Doses were escalated sequentially in single pts (6 and 12 mg/m2) and 3–6 pts (≥ 25 mg/m2) cohorts according to a modified Fibonacci’s schema. Plasma pharmacokinetic (PK) profiles were obtained on days 1 and 18. Biomarkers were measured in PBMC’s (HSP70) and plasma (HER-2 ectodomain (HER-2 ECD)). Results: 30 pts (M/F: 14/16; median age 63, range 48–78) with colorectal cancer (11), pancreatic cancer (5), melanoma (5), ovarian (2), others (7) were treated with a median of 2 courses (range: 1–10). There was no dose-limiting toxicity up to 175 mg/m2. One pt at 175 mg/m2 died on study, but drug relation was unclear. Grade 1–2 gastrointestinal toxicities (nausea, vomiting, diarrhea) and serum creatinine elevation were observed. Severe toxicities (grade 3 but no grade 4) consisted of reversible hepatic enzyme elevation, hyperbilirubinemia, fatigue, anemia and hyperglycemia. There were no hematological toxicities. Plasma 17-AAG PK appeared dose-proportional (AUC, Cmax); CL (17 L/h/m2) and t1/2 (5.2 h) were dose independent and unchanged after repeated dosing (day 18). Post-treatment increases in HSP70 were observed in PBMCs and decreases in plasma HER-2 ECD were observed at doses ≥ 83 mg/m2. Minor tumor regressions were seen in 1 pt with duodenal cancer (83 mg/m2), 1 pt with gastric carcinoid (175 mg/m2) and 1 pt with melanoma (175 mg/m2). Conclusion: The threshold of biologic activity for CNF1010 administered by a twice a week schedule appears to be 83 mg/m2. This dosing regimen appears to be optimal and supported by the pharmacokinetic and pharmacodynamic data. The MTD has not yet been determined. Dose escalation of CNF1010 continues at 225 mg/m2.

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A phase I and pharmacologic study of sequences of the proteasome inhibitor, bortezomib (PS-341, Velcade), in combination with paclitaxel and carboplatin in patients with advanced malignancies

PURPOSE

Bortezomib, a selective inhibitor of the 20S proteasome with activity in a variety of cancers, exhibits sequence-dependent synergistic cytotoxicity with taxanes and platinum agents. Two different treatment schedules of bortezomib in combination with paclitaxel and carboplatin were tested in this phase I study to evaluate the effects of scheduling on toxicities, pharmacodynamics and clinical activity.

METHODS

Patients with advanced malignancies were alternately assigned to receive (schedule A) paclitaxel and carboplatin (IV d1) followed by bortezomib (IV d2, d5, d8) or (schedule B) bortezomib (IV d1, d4, d8) followed by paclitaxel and carboplatin (IV d2) on a 21-day cycle.

RESULTS

Fifty-three patients (A 25, B 28) were treated with a median of 3 cycles (range 1-8) for schedule A and 3.5 cycles (range 1-10) for schedule B. Grade 3 or higher treatment related hematologic adverse events in all cycles of treatment included neutropenia (A 52%, B 50%), anemia (A 12%, B 7.1%) and thrombocytopenia (A 16%, B 17.9%). Non-hematologic treatment related adverse events were fairly mild (primarily grades 1 and 2). The maximum tolerated dose and the recommended doses for future phase II trials are bortezomib 1.2 mg/m2, paclitaxel 135 mg/m2 and carboplatin AUC = 6 for schedule A and bortezomib 1.2 mg/m2, paclitaxel 175 mg/m2 and carboplatin AUC = 6 for schedule B. Six (21.4%) partial responses (PR) were seen with schedule B. In contrast, only 1 (4%) PR was achieved with schedule A. Similar proteasome inhibition was achieved at MTD for both schedules.

CONCLUSION

Administration of sequential bortezomib followed by chemotherapy (schedule B) was well tolerated and associated with an encouraging number of objective responses in this small group of patients. Further studies with this administration schedule are warranted.

Phase I study of EKB-569, an irreversible inhibitor of the epidermal growth factor receptor, in patients with advanced solid tumors

PURPOSE

The maximum tolerated dose (MTD) and the dose-limiting toxicities of EKB-569, a selective, irreversible inhibitor of the epidermal growth factor receptor (EGFR), when administered orally once daily on an intermittent-dose schedule (14 days of a 28-day cycle) or on a continuous-dose schedule (each day of a 28-day cycle), were determined in patients with advanced solid tumors.

PATIENTS AND METHODS

Planned dose escalation was 25, 50, 75, 125, 175, and 225 mg. Pharmacokinetic sampling was performed on days 1 and 14 for the intermittent-dose cohort and on days 1 and 15 for the continuous-dose cohort.

RESULTS

Thirty patients received a median of two cycles (range, one to 10 cycles) in the intermittent-dose cohort; 29 patients received a median of three cycles (range, one to eight cycles) in the continuous-dose cohort. Dose-limiting toxicity was grade 3 diarrhea, and the MTD was 75 mg EKB-569 per day for both cohorts. Other common toxicities included rash, nausea, and asthenia. Exposure to EKB-569 was dose proportional. At the MTD, the mean +/- standard deviation terminal half-life was 21.7 +/- 4.2 hours and peak concentration increased 1.2-fold from day 1 to day 14/15. No major antitumor responses were observed. However, one patient with non-small-cell lung cancer and one with cutaneous squamous cell carcinoma had stable disease for 33 and 24 weeks, respectively.

CONCLUSION

The MTD of once-daily oral EKB-569 is 75 mg. The tolerable toxicity profile and long half-life of this irreversible EGFR inhibitor warrant its further evaluation as a single agent and in combination with other drugs.

A measles virus vaccine strain derivative as a novel oncolytic agent against breast cancer

Breast cancer is the most common malignancy and the second leading cause of female cancer mortality in the United States. There is an urgent need for development of novel therapeutic approaches. In this study, we investigated the antitumor potential of a novel viral agent, an attenuated strain of measles virus deriving from the Edmonston vaccine lineage, genetically engineered to produce carcinoembryonic antigen (CEA) against breast cancer. CEA production as the virus replicates can serve as a marker of viral gene expression. Infection of a variety of breast cancer cell lines including MDA-MB-231, MCF7 and SkBr3 at different multiplicities of infection (MOIs) from 0.1 to 10 resulted in significant cytopathic effect consisting of extensive syncytia formation and massive cell death at 72-96 h from infection. All breast cancer lines overexpressed the measles virus receptor CD46 and supported robust viral replication, which correlated with CEA production. TUNEL assays indicated an apoptotic mechanism of syncytial death. The efficacy of this approach in vivo was examined in a subcutaneous Balb C/nude mouse model of MDA-MB-231 cells. Intravenous administration of MV-CEA at a total dose of 1.2 x 10(7) TCID50 resulted in statistically significant tumor growth delay ( p=0.005) and prolongation of survival ( p=0.001). In summary, MV-CEA has potent antitumor activity against breast cancer lines and xenografts. Monitoring marker peptide levels in the serum could serve as a low-risk method of detecting viral gene expression during treatment and could allow dose optimization and individualization of treatment. Trackable measles virus derivatives merit further exploration in breast cancer treatment.

Flavopiridol in patients with relapsed or refractory multiple myeloma: a phase 2 trial with clinical and pharmacodynamic end-points

Flavopiridol downregulates anti-apoptotic regulators including Mcl-1, upregulates p53, globally attenuates transcription through inhibition of P-TEFb, binds to DNA, and inhibits angiogenesis. Eighteen myeloma patients were treated with 1-hour flavopiridol infusions for 3 consecutive days every 21 days. Immunoblotting for Mcl-1, Bcl-2, p53, cyclin D, phosphoRNA polymerase II and phosphoSTAT 3 was conducted on myeloma cells. Ex vivo flavopiridol treatment of cells resulted in cytotoxicity, but only after longer exposure times at higher flavopiridol concentrations than were anticipated to be achieved in vivo. No anti-myeloma activity was observed in vivo. As administered, flavopiridol has disappointing activity as a single agent in advanced myeloma.