Distinct uptake and elimination profiles for trastuzumab, human IgG and biocytin-TMR in experimental HER2+ brain metastases of breast cancer

BACKGROUND

The aim of this study is an improved understanding of drug distribution in brain metastases. Rather than single point snapshots, we analyzed the time course and route of drug/probe elimination (clearance), focusing on the Intramural Periarterial Drainage (IPAD) pathway.

METHODS

Mice with JIMT1-BR HER2+ experimental brain metastases were injected with biocytin-TMR and either trastuzumab or human IgG. Drugs/probes circulated for 5 min-48h, followed by perfusion. Brain sections were stained for human IgG, vascular basement membrane proteins laminin or collagen IV, and periarterial α-SMA. A machine learning algorithm was developed to identify metastases, metastatic microenvironment, and uninvolved brain in confocally scanned brain sections. Drug/probe intensity over time and total imaged drug exposure (iAUC) were calculated for 27,249 lesions and co-immunofluorescence with IPAD- vascular matrix analyzed in 11,668 metastases.

RESULTS

In metastases, peak trastuzumab levels were 5-fold higher than human IgG but 4-fold less than biocytin-TMR. The elimination phase constituted 85-93% of total iAUC for all drugs/probes tested. For trastuzumab, total iAUC during uptake was similar to the small molecule drug probe biocytin-TMR, but slower trastuzumab elimination resulted in a 1.7-fold higher total iAUC. During elimination trastuzumab and IgG were preferentially enriched in the α-SMA+ periarterial vascular matrix, consistent with the IPAD clearance route; biocytin-TMR showed heterogeneous elimination pathways.

CONCLUSIONS

Drug/probe elimination is an important component of drug development for brain metastases. We identified a prolonged elimination pathway for systemically administered antibodies through the periarterial vascular matrix that may contribute to the sustained presence and efficacy of large antibody therapeutics.

The Combination of Trametinib and Ganitumab is Effective in RAS-Mutated PAX-Fusion Negative Rhabdomyosarcoma Models

PURPOSE

PAX-fusion negative rhabdomyosarcoma (FN RMS) is driven by alterations in the RAS/MAP kinase pathway and is partially responsive to MEK inhibition. Overexpression of IGF1R and its ligands is also observed in FN RMS. Preclinical and clinical studies have suggested that IGF1R is itself an important target in FN RMS. Our previous studies revealed preclinical efficacy of the MEK1/2 inhibitor, trametinib, and an IGF1R inhibitor, BMS-754807, but this combination was not pursued clinically due to intolerability in preclinical murine models. Here, we sought to identify a combination of an MEK1/2 inhibitor and IGF1R inhibitor, which would be tolerated in murine models and effective in both cell line and patient-derived xenograft models of RAS-mutant FN RMS.

EXPERIMENTAL DESIGN

Using proliferation and apoptosis assays, we studied the factorial effects of trametinib and ganitumab (AMG 479), a mAb with specificity for human and murine IGF1R, in a panel of RAS-mutant FN RMS cell lines. The molecular mechanism of the observed synergy was determined using conventional and capillary immunoassays. The efficacy and tolerability of trametinib/ganitumab was assessed using a panel of RAS-mutated cell-line and patient-derived RMS xenograft models.

RESULTS

Treatment with trametinib and ganitumab resulted in synergistic cellular growth inhibition in all cell lines tested and inhibition of tumor growth in four of six models of RAS-mutant RMS. The combination had little effect on body weight and did not produce thrombocytopenia, neutropenia, or hyperinsulinemia in tumor-bearing SCID beige mice. Mechanistically, ganitumab treatment prevented the phosphorylation of AKT induced by MEK inhibition alone. Therapeutic response to the combination was observed in models without a mutation in the PI3K/PTEN axis.

CONCLUSIONS

We demonstrate that combined trametinib and ganitumab is effective in a genomically diverse panel of RAS-mutated FN RMS preclinical models. Our data also show that the trametinib/ganitumab combination likely has a favorable tolerability profile. These data support testing this combination in a phase I/II clinical trial for pediatric patients with relapsed or refractory RAS-mutated FN RMS.

Abstract IA023: Therapeutic efficacy of trametinib and ganitumab in RAS-mutated rhabdomyosarcoma

Background: PAX-fusion negative rhabdomyosarcoma (FN RMS) is driven by alterations in the RAS/MAP kinase pathway and is partially responsive to MEK inhibition. Overexpression of IGF1R and its ligands is also observed in FN RMS. Preclinical and clinical studies have suggested that IGF1R is itself an important target in FN RMS. Our previous studies revealed preclinical efficacy of the MEK1/2 inhibitor, trametinib, and an IGF1R inhibitor, BMS75807, but this combination was not pursued clinically due to excessive toxicity in preclinical murine models. Here, we sought to identify a combination of an MEK1/2 inhibitor and IGF1R inhibitor that would be better tolerated in murine models and effective in both cell line and patient derived xenograft models of RAS-mutant FN RMS. Methods: Using proliferation and apoptosis assays, we studied the factorial effects of trametinib and ganitumab (AMG 479), a monoclonal antibody with specificity for human and murine IGF1R, in a panel of RAS-mutant FN RMS cell lines. The molecular mechanism of the observed synergy was determined using conventional and capillary immunoassays. The efficacy and tolerability of the combination was assessed using a panel of RAS-mutated cell-line and patient-derived RMS xenograft models. Results: Treatment with trametinib and ganitumab resulted in synergistic cellular growth inhibition in all cell lines tested and inhibition of tumor growth in five out of six models of RAS-mutant RMS. Evidence suggests that the combination had little effect on body weight loss, thrombocytopenia, neutropenia, or hyperinsulinemia in tumor-bearing SCID beige mice. Mechanistically, ganitumab treatment prevented the AKT phosphorylation that is induced by MEK inhibition alone. Therapeutic response to the combination was observed in models with an intact PI3K/PTEN axis. Conclusions: We demonstrate that combined trametinib and ganitumab is effective in a genomically diverse panel of RAS-mutated FN RMS preclinical models. The trametinib/ganitumab combination also likely has an improved tolerability profile compared to other IGF1R/MEK inhibitor combinations. These data support testing this combination in a phase I/II clinical trial for pediatric patients with relapsed or refractory RAS-mutated FN RMS.

Citation Format: Marielle E. Yohe, Katie E. Hebron, Xiaolin Wan, Jacob S. Roth, David J. Liewehr, Nancy E. Sealover, Stacey Stauffer, Olivia Feehan-Nelson, Wenyue Sun, Kristine A. Isanogle, Christina M. Robinson, Amy James, Parirokh Awasthi, Priya Shankarappa, Xiaoling Liu, Haiyan Lei, Donna Butcher, Roberta Smith, Elijah F. Edmonson, Jin-Qui Chen, Noemi Kedei, Cody S. Peer, Jack F. Shern, W. Douglas Figg, Lu Chen, Matthew D. Hall, Simone Difillipantonio, Frederic G. Barr, Robert L. Kortum, Angelina V. Vaseva, Javed Khan. Therapeutic efficacy of trametinib and ganitumab in RAS-mutated rhabdomyosarcoma [abstract]. In: Proceedings of the AACR Special Conference: Sarcomas; 2022 May 9-12; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(18_Suppl):Abstract nr IA023.

Biological Effects of Modifications of the Englerin A Glycolate

Modifications at the glycolate moiety of englerin A were made to explore variations at the most sensitive site on the molecule for activity in the NCI 60 screen, wherein englerin A is highly potent and selective for renal cancer cells. Replacement of the glycolate by other functionalities as well as esterification of the glycolate hydroxyl yielded compounds which displayed excellent selectivity and potency compared with the natural product. TRPC4/5 ion channel experiments with five compounds showed delayed or reduced agonism with TRPC5, at much higher concentrations than englerin A. With TRPC4, these compounds all had no effect at 10 μM. The same compounds were not detectable in mouse serum after a single oral dose of 12.5 mg/kg. At 100 mg/kg p.o., no toxicity was observed, and blood levels were barely detectable. Intravenous administration led to toxicity but at substantially lower doses than for englerin A.

EPCT-16. LENALIDOMIDE ACTIVITY IN PILOCYTIC ASTROCYTOMA AND OPTIC PATHWAY GLIOMAS: REPORT ON CHILDREN’S ONCOLOGY GROUP ACNS1022

Children with low-grade glioma have excellent survival rates but often suffer from the morbidity of treatment, particularly from cytotoxic chemotherapies. Targeted agents appear to have some activity but the long-term effects of inhibiting normal developmental pathways are unknown. Lenalidomide is an oral immunomodulatory agent with additional properties including anti-angiogenesis. Phase I studies indicated greater tolerability of this agent compared to adults, and a potential dose-response effect. We performed a Phase 2 trial of lenalidomide in children with pilocytic astrocytoma and optic pathway gliomas who failed initial therapy. The primary objective was to determine the objective response rate of children randomized to Regimen A low-dose (20 mg/m² /dose) or Regimen B high-dose (115 mg/m² /dose) lenalidomide, each administering lenalidomide daily x 21 days of each 28-day course. Secondary objectives included estimation of event-free survival (EFS) in this population and correlation of plasma lenalidomide concentration with toxicity and outcome.

Results

74 eligible patients were enrolled (n=37 to each arm). The pre-defined activity level of interest was achieved for both arms. Objective responses were observed in both arms, with 4 partial responses in each. A total of n=18 patients completed 26 courses of therapy (Arm A, n=12, Arm B, n=6) The median number of courses on each arm was 14 (range 2–26) for Arm A and 11 for Arm B (range 1- 26). Of the 74 eligible patients who received study drug, 30 required a dose reduction for toxicity (Arm A, n=6, Arm B, n=24) and 16 discontinued treatment on protocol due to toxicity (Arm A, n=2, Arm B, n=14).

Conclusion

Lenalidomide demonstrates a sufficient level of activity in children with low-grade glioma to warrant further exploration in Phase 3 studies. Low-dose (20 mg/m²) lenalidomide appears to have better tolerability.

EPCT-09. CNS LEVELS OF PANOBINOSTAT IN A NON-HUMAN PRIMATE MODEL: COMPARISON OF BLOOD AND CEREBROSPINAL FLUID PHARMACOKINETIC METHODS AND MALDI MSI

Adequate exposure (effective concentration over time) of a therapeutic agent at its site of action is essential for antitumor efficacy. Given constraints of repeat tissue sampling, non-human primate models predictive of pharmacokinetics in pediatric patients have been utilized to assess central nervous system (CNS) exposure. Assessment of cerebrospinal fluid (CSF) drug levels have been used to extrapolate CNS penetration but the relationship of CSF drug levels with tissue distribution is unclear. Utilizing microdialysis, we previously demonstrated geographic variability of drug permeability across the blood:brain barrier (BBB), but this technique is complex and has a high standard deviation. We, therefore, explored a novel technique, matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI), to compare plasma, CSF, and tissue drug levels in a terminal non-human primate model. Panobinostat, an HDAC inhibitor in clinical trials for DIPG/DMG, was selected for study as it has previously demonstrated poor CNS tissue penetration but suggested modest clinical activity.

Methods

Panobinostat (p.o., dose 1.6 mg/kg) was administered to non-tumor bearing primates (n=2). One hour following administration (Tmax), blood and CSF were collected, the animal euthanized, brain and spinal cord extracted, and immediately frozen at -80. Panobinostat distribution was mapped on ex vivo sagittal tissue sections using MALDI MSI. To provide specificity and degree of permeability, anatomical structures were segmented for analysis to determine drug concentrations. Blood, CSF and tissue levels of panobinostat were measured via LC-MS/MS.

Results

Segmentation analysis revealed quantifiable panobinostat, particularly in the lateral ventricles and choroid plexus, and also in the subventricular zone and brainstem, although the overall panobinostat concentration was below the limit of quantitation in these areas.

Conclusions

Although not reflected in CSF PK, panobinostat is widely distributed in brain tissue. MALDI MSI allows regional assessment of panobinostat penetration and complements CSF pharmacokinetics.

Abstract OT-26-03: Racial disparities in CYP3A variants in the metabolism of ribociclib in breast cancer patients

Background:Ribociclib is an inhibitor of the cyclin dependent kinases 4 and 6 (CDK 4/6) and is approved in combination with endocrine therapy for patients with advanced hormone receptor (HR) positive metastatic breast cancer (mBC). CYP3A inhibitors increase ribociclib area under the curve (AUC) by 3.2-fold; this is of clinical concern given possible associations between exposure and toxicity (e.g., QTc prolongation and neutropenia). Although there is an FDA recommendation to modify therapy for patients prescribed CYP3A inhibitors, it is unknown if modifications are needed in patients who intrinsically lack enzyme activity (e.g., genetic CYP3A5 poor metabolizers). CYP3A function is largely derived from CYP3A4 and CYP3A5 isozymes in adults. It is difficult to differentiate relative contributions of CYP3A4 and CYP3A5 on CYP3A function due to sequence homology (~ 84%) and overlapping substrate specificity. Genetic variations in CYP3A5 can translate into poor, intermediate, or normal CYP3A5 metabolism of different substrates and some pharmaceutics metabolized by CYP3A have dosing recommendations based on genotype. We hypothesize that patients harboring genetic variants causing CYP3A5 poor metabolism experience increased exposure to ribociclib and likely more toxicities. Race is likely to be significant factor when exploring ribociclib pharmacokinetics (PK) and the role of CYP3A. There are known race-based differences in CYP3A4 and CYP3A5, with alleles associated with CYP3A5 loss prevalent in European Americans (EA) and not in African Americans (AA). Ribociclib PK have not been adequately studied in AA with 3% of participants in the pivotal trials AA. We aim to determine the pharmacokinetic and pharmacogenomic association between ribociclib exposure and CYP3A variants in AA and EA patients. Our findings should allow clinicians to tailor treatments to maintain therapeutic doses while limiting toxicities. Methods:This prospective, multicenter, open-label pilot study will assess ribociclib (600 mg PO daily) PK and pharmacogenomics in female patients with HR+/HER2- mBC. This design will be two independent, race-based cohorts: 18 AA patients and 18 EA patients. Eligibility include: female, >18, HR+/HER2- mBC and candidates for treatment with a CDK 4/6 inhibitor and endocrine therapy. Patients are ineligible if currently prescribed a medication that inhibits or induces the CYP3A isozymes, have baseline EKG abnormalities, or are otherwise considered to be ineligible for ribociclib. Participants will provide serial blood samples during the first cycle. Plasma samples will be analyzed via mass spectrometry to characterize the PK (e.g., AUC0-24, Cmax). Pharmacogenetic testing will be performed using the PharmacoScanTM microarray, which tests 4627 markers in 1191 genes, including 73 variants in CYP3A4 and CYP3A5. The primary endpoint will compare ribociclib AUC between CYP3A5 poor metabolizers vs. intermediate or normal CYP3A5 metabolizers within separate, race-based cohorts. Secondary endpoints include characterization of PK properties of ribociclib in the AA and EA populations. We also will seek to identify if CYP3A5, CYP3A4, or other variants are associated to different toxicity profiles. In addition, we will perform a hypothesis-generating PGx correlative analysis for potential biomarkers of ribociclib PK or toxicity. The primary outcome is powered to detect a minimum clinically meaningful change, a 2-fold change in AUC, which is less than the 3.2-fold change seen in the mentioned CYP3A drug interaction pharmacokinetic study. Based on CYP3A5 allelic frequencies, a sample size of 36 will provide 80% power to independently test the primary outcome in the two race-based cohorts.

Funding: Breast Cancer Research Foundation. Contact: Sandra Swain MD, sandra.swain@georgetown.edu

Citation Format: Ilana Schlam, D. Max Smith, Ian Chang, Asma Dilawari, Cody Peer, Tristan Sissung, Ming Tan, W. Douglas Figg, Sandra M. Swain. Racial disparities in CYP3A variants in the metabolism of ribociclib in breast cancer patients [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr OT-26-03.

A phase I trial of lenalidomide and radiotherapy in children with diffuse intrinsic pontine gliomas or high-grade gliomas

PURPOSE

This study was performed to determine the maximum tolerated dose (MTD) or recommended phase 2 dose (RP2D) of the immunomodulatory agent, lenalidomide, when administered daily during 6 weeks of radiation therapy to children with newly diagnosed diffuse intrinsic pontine glioma (DIPG) or high-grade glioma (HGG) PATIENTS & METHODS: Children and young adults < 22 years of age with newly diagnosed disease and no prior chemotherapy or radiation therapy were eligible. Children with HGG were required to have an inoperable or incompletely resected tumor. Eligible patients received standard radiation therapy to a prescription dose of 54-59.4 Gy, with concurrent administration of lenalidomide daily during radiation therapy in a standard 3 + 3 Phase I dose escalation design. Following completion of radiation therapy, patients had a 2-week break followed by maintenance lenalidomide at 116 mg/m²/day × 21 days of a 28-day cycle.

RESULTS

Twenty-nine patients (age range 4-19 years) were enrolled; 24 were evaluable for dose finding (DIPG, n = 13; HGG, n = 11). The MTD was not reached at doses of lenalidomide up to 116 mg/m²/day. Exceptional responses were noted in DIPG and malignant glioma (gliomatosis cerebri) notably at higher dose levels and at higher steady state plasma concentrations. The primary toxicity was myelosuppression.

CONCLUSION

The RP2D of lenalidomide administered daily during radiation therapy is 116 mg/m²/day. Children with malignant gliomas tolerate much higher doses of lenalidomide during radiation therapy compared to adults. This finding is critical as activity was observed primarily at higher dose levels suggesting a dose response.

First-in-human phase 0 study of 111In-CHX-A"-DTPA trastuzumab for HER2 tumor imaging

Introduction:

Tumors over-expressing the human epithelial receptor 2 (HER2) or exhibiting amplification or mutation of its proto-oncogene have a poorer prognosis. Using trastuzumab and/or other HER2 targeted therapies can increase overall survival in patients with HER2(+) tumors making it critical to accurately identify patients who may benefit. We report on a Phase 0 study of the imaging agent, ¹¹¹In-CHX-A”-DTPA trastuzumab, in patients with known HER2 status to evaluate its safety and biodistribution and to obtain preliminary data regarding its ability to provide an accurate, whole-body, non-invasive means to determine HER2 status.

Methods:

¹¹¹In-CHX-A”-DTPA trastuzumab was radiolabeled on-site and slowly infused into 11 patients who underwent single (n=5) or multiple (n=6) ɣ-camera (n=6) and/or SPECT (n=8) imaging sessions.

Results:

No safety issues were identified. Visual and semi-quantitative imaging data were concordant with tissue HER2 expression profiling in all but 1 patient. The biodistribution showed intense peak liver activity at the initial imaging timepoint (3.3h) and a single-phase clearance fit of the average time-activity curve (TAC) estimated t_1/2=46.9h (R²=0.97; 95%CI 41.8 to 53h). This was followed by high gastrointestinal (GI) tract activity peaking by 52h. Linear regression predicted GI clearance by 201.2h (R² =0.96; 95%CI 188.5 to 216.9h). Blood pool had lower activity with its maximum on the initial images. Non-linear regression fit projected a t_1/2=34.2h (R² =0.96; 95%CI 25.3 to 46.3h). Assuming linear whole-body clearance, linear regression projected complete elimination (x-intercept) at 256.5hr (R²=0.96; 95%CI 186.1 to 489.2h).

Conclusion:

¹¹¹In-CHX-A”-DTPA trastuzumab can be safely imaged in humans. The biodistribution allowed for visual and semiquantitative analysis with results concordant with tissue expression profiling in 10 of 11 patients. Advances in Knowledge and Implications for Patient Care Using readily available components and on-site radiolabeling ¹¹¹In-CHX-A”-DTPA trastuzumab SPECT imaging may provide an economical, non-invasive means to detect HER2 over-expression.

A Phase II Study of 5-AZA-2'Deoxycytidine (Decitabine) in Hormone Independent Metastatic (D2) Prostate Cancer

Aims and Background

Decitabine (5-aza-2′-deoxycytidine) is an S-phase-specific pyrimidine analog with hypomethylation properties. In laboratory models of prostate cancer (PC-3 and DU-145), decitabine induces cellular differentiation and enhanced expression of genes involved in tumor suppression, immunogenicity, and programmed cell death.

Methods

We conducted a phase II study of decitabine in 14 men with progressive, metastatic prostate cancer recurrent after total androgen blockade and flutamide withdrawal. Decitabine was administered at a dose of 75 mg/m2/dose IV as a 1 hour infusion every 8 hours for three doses. Cycles of therapy were repeated every 5 to 8 weeks to allow for resolution of toxicity.

Results

Two of 12 patients evaluable for response had stable disease with a time to progression of more than 10 weeks. This activity was seen in 2 of 3 African-American patients. Toxicity was similar to previously reported experience. No significant changes in urinary concentrations of the angiogenic factor bFGF, a potential biomarker of tumor activity, were identified over time in 7 unselected patients with progressive disease.

Conclusions

We conclude that decitabine is a well tolerated regimen with modest clinical activity against hormone-independent prostate cancer. Further investigations in patients of African-American origin may be warranted.

Abstract P1-01-01: The blood-Tumor barrier as a therapeutic target to improve therapy of brain metastases of breast cancer

Objectives: Brain metastases of breast cancer demonstrate low and heterogeneous levels of permeability to drugs in mouse models and human craniotomies. The Blood-Brain Barrier (BBB), the protective lining of CNS blood vessels, impedes drug entry into the normal brain. When a metastasis forms, the BBB is locally altered to a poorly characterized Blood-Tumor Barrier (BTB). Quantitative experimental models indicate that most brain metastases have increased permeability over the normal BBB, but BTB permeability is both heterogeneous and ˜2 logs less than that of systemic metastases. We have interrogated three hematogenous models of brain metastasis of breast cancer to ask (1) whether the BTB is an ordered structure or a random breakdown of the BBB; (2) among brain metastases, whether consistent differences underlie the BTBs of lesions with low- and high permeabilities to fluorescent markers and drugs; (3) if alterations in BTB composition can functionally change its permeability. Our long term goal is to enhance uptake of drugs into brain metastases to effective levels.

Results: When uninvolved brain was compared with any brain metastasis, alterations in endothelial, pericytic, astrocytic, and microglial components of the BBB were observed. Both the pericyte and astrocyte components of the BTB were consistently altered with increased permeability: When metastases with relatively low and high permeability were compared, increased expression of a desmin+ subpopulation of pericytes was associated with higher permeability (231-BR6 P=0.0002; JIMT-1-BR3 P = 0.004; SUM190-BR3 P=0.008). A trend toward reduced CD13+ pericytes was observed in highly permeable metastases (231-BR6 P =0.014; JIMT-1-BR3 P =0.002, SUM190-BR3, NS). For GFAP+ astrocytes in the neuroinflammatory response surrounding metastases, no overall difference in cell number was observed between low and high permeability lesions. However, gene expression profiling of laser capture microdissected low and high permeabililty lesions demonstrated overexpression of the sphingosine-1 phosphate receptor 3 (S1P3) in the astrocytes of highly permeable lesions, which was confirmed at the protein expression level in all three models (231-BR6 P=0.034; JIMT-1-BR3 P = 0.01; SUM190-BR3 P=0.016). Inhibition of S1P3 via S1PR3 shRNA or a selective antagonist (TY-52156) functionally tightened the BTB in an in vitro model. Administration of TY-52156 to mice harboring 231-BR6 brain metastases had no effect on metastasis number, but decreased uptake of Texas Red Dextran dye into metastases (P=0.016). S1P3 mediated its effects on BTB permeability through astrocytic secretion of IL-6 and CCL2, which altered endothelial expression and localization of adhesive proteins, a potentially translatable pathway. Both desmin+ pericytes and S1P3+ astrocytes are present in human craniotomy specimens.

Conclusions: These experiments demonstrate that the BTB is a structure with consistent properties, and that further consistent changes underlie the transition from a low to high permeability BTB. While proof of principle, S1P3 inhibition studies indicate that the BTB permeability can be functionally modulated in vivo.

Citation Format: Steeg PS, Lyle TR, Paranjapee A, Lockman PR, Duchnowska R, Brastianos PK, Peer C, Figg WD, Pauly GT, Schneider JP, Smith QR, Gril B. The blood-Tumor barrier as a therapeutic target to improve therapy of brain metastases of 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 P1-01-01.

A phase I dose expansion cohort study of dasatinib in combination with bevacizumab in advanced solid tumors (NCT01445509)

2585

Background: Dasatinib is a known inhibitor of the SRC family kinases and is approved for use in chronic myelogenous leukemia. Bevacizumab inhibits angiogenesis, binding to human vascular endothelial growth factor (VEGF, or VEGF-A) with high affinity. VEGF receptor signals intracellularly via a cascade regulated by SRC. Given the presence of this signaling pathway in both tumor cells and endothelial cells, we hypothesized that attenuation of both SRC and VEGF simultaneously would have synergistic antitumor activity. We previously reported the maximum tolerated dose (MTD) of dasatinib 100mg daily with bevacizumab 10mg/kg q2wk in patients with advanced solid tumors. We now report clinical activity of the combination, and translational endpoints of an expansion cohort. Methods: This is a phase 1 dose escalation with non-randomized expansion cohort. We monitored safety, and response was assessed every 8 weeks using RECIST criteria. Correlative endpoints include blood flow by dynamic MR imaging, endothelial cell density by CD31 immunohistochemistry, functional angiogenic potential by plasma cytokines and rat aortic ring assay, and tumor cell activation state by phosphoprotein analysis. Results: We enrolled 39 patients at the MTD for a total of 50 patients on study, including both the dose escalation and dose expansion phases. No patient experienced dose limiting toxicities during dose escalation. The most common adverse events were grade 2 hypertension and proteinuria. By RECIST, 5 (10%) patients had a partial response, and stable disease was seen in 29 (58%) of patients with a range from 12-145+ weeks on study. We had two exceptional responders with endometrial carcinoma who continue on study to date (112 weeks and 145 weeks). Translational endpoints were correlated with clinical outcome. Conclusions: Bevacizumab and dasatinib are safe in combination, with potential clinical activity. This combination warrants further investigation in solid tumors. Ongoing translational research using specimens from exceptional responders will suggest potential biomarkers of clinical benefit, to be tested in future prospective clinical trials. Clinical trial information: NCT01445509.

Modulation of tumor eIF4E by antisense inhibition: A phase I/II translational clinical trial of ISIS 183750-an antisense oligonucleotide against eIF4E-in combination with irinotecan in solid tumors and irinotecan-refractory colorectal cancer

The eukaryotic translation initiation factor 4E (eIF4E) is a potent oncogene that is found to be dysregulated in 30% of human cancer, including colorectal carcinogenesis (CRC). ISIS 183750 is a second-generation antisense oligonucleotide (ASO) designed to inhibit the production of the eIF4E protein. In preclinical studies we found that EIF4e ASOs reduced expression of EIF4e mRNA and inhibited proliferation of colorectal carcinoma cells. An additive antiproliferative effect was observed in combination with irinotecan. We then performed a clinical trial evaluating this combination in patients with refractory cancer. No dose-limiting toxicities were seen but based on pharmacokinetic data and tolerability the dose of irinotecan was reduced to 160 mg/m(2) biweekly. Efficacy was evaluated in 15 patients with irinotecan-refractory colorectal cancer. The median time of disease control was 22.1 weeks. After ISIS 183750 treatment, peripheral blood levels of eIF4E mRNA were decreased in 13 of 19 patients. Matched pre- and posttreatment tumor biopsies showed decreased eIF4E mRNA levels in five of nine patients. In tumor tissue, the intracellular and stromal presence of ISIS 183750 was detected by IHC in all biopsied patients. Although there were no objective responses stable disease was seen in seven of 15 (47%) patients who were progressing before study entry, six of whom were stable at the time of the week 16 CT scan. We were also able to confirm through mandatory pre- and posttherapy tumor biopsies penetration of the ASO into the site of metastasis.

Synthesis of a stable and orally bioavailable englerin analogue

Synthesis of analogues of englerin A with a reduced propensity for hydrolysis of the glycolate moiety led to a compound which possessed the renal cancer cell selectivity of the parent and was orally bioavailable in mice.

Pharmacodynamic markers and clinical results from the phase 2 study of the SMAC mimetic birinapant in women with relapsed platinum-resistant or -refractory epithelial ovarian cancer

BACKGROUND

Inhibitors of apoptosis proteins (IAPs) are key regulators of apoptosis and are frequently dysregulated in ovarian cancer. It was hypothesized that blocking IAPs with birinapant would increase tumor cell death and result in objective responses for women with platinum-refractory and -resistant ovarian cancer.

METHODS

In this phase 2, Cancer Therapy Evaluation Program-sponsored study, patients received birinapant at 47 mg/m(2) on days 1, 8, and 15 of 28-day cycles. Pharmacokinetics were obtained during cycle 1. Plasma, peripheral blood mononuclear cells (PBMCs), and percutaneous tumor biopsy samples were collected before cycle 1 and after 6 weeks. The primary endpoint was an objective response or progression-free survival lasting greater than 6 months in a mini-max design.

RESULTS

Eleven patients received birinapant; after this, accrual was terminated for lack of a clinical benefit. Birinapant was well tolerated, with predominantly grade 2 adverse events and 1 case of grade 3 lymphopenia. Pretreatment biopsy samples and PBMCs were collected; paired posttreatment biopsy samples and PBMCs were collected from 7 and 10 patients, respectively. There was consistent downregulation of cellular inhibitor of apoptosis protein 1 in tumors (P = .016) and PBMCs (P < .01). Procaspase 3 also decreased in tumors (P = .031) and PBMCs (P < .01); cleaved caspase 3 colocalized with H2A histone family member X (γ-H2AX) in tumors after birinapant exposure. Peripheral T and B cells decreased significantly after treatment, but natural killer cells did not (P = .04, P = .05, and P = .43, respectively).

CONCLUSIONS

Birinapant shows consistent target suppression in vivo without single-agent antitumor activity in this small population. Single-agent pharmacodynamics are necessary to understand the drug's mechanism of action and set the stage for rational combination therapy. Preclinical studies are ongoing to identify optimal synergistic combinations for future clinical trials.

A phase II study of TRC105 in patients with hepatocellular carcinoma who have progressed on sorafenib

BACKGROUND

Endoglin is an endothelial cell membrane receptor essential for angiogenesis and highly expressed on the vasculature of many tumor types, including hepatocellular carcinoma (HCC). TRC105 is a chimeric IgG1 anti-CD105 monoclonal antibody that inhibits angiogenesis and tumor growth by endothelial cell growth inhibition, ADCC and apoptosis, and complements VEGF inhibitors.

OBJECTIVE

The aim of this phase II study was to evaluate the efficacy of anti-endoglin therapy with TRC105 in patients with advanced HCC, post-sorafenib.

METHODS

Patients with HCC and compensated liver function (Childs-Pugh A/B7), ECOG 0/1, were enrolled to a single-arm, phase II study of TRC105 15 mg/kg IV every two weeks. Patients must have progressed on or been intolerant of prior sorafenib. A Simon optimal two-stage design was employed with a 50% four-month PFS target for progression to the second stage. Correlative biomarkers evaluated included DCE-MRI as well as plasma levels of angiogenic biomarkers and soluble CD105.

RESULTS

A total accrual of 27 patients was planned. However, because of lack of efficacy and in accordance with the Simon two-stage design, 11 patients were enrolled. There were no grade 3/4 treatment-related toxicities. Most frequent toxicities were headache (G2; N = 3) and epistaxis (G1; N = 4). One patient had a confirmed partial response by standard RECIST criteria and biologic response on DCE-MRI but the four-month PFS was insufficient to proceed to the second stage of the study.

CONCLUSIONS

TRC105 was well tolerated in this HCC population following sorafenib. Although there was evidence of clinical activity, this did not meet prespecified criteria to proceed to the second stage. TRC105 development in HCC continues as combination therapy with sorafenib.

Abstract CT222: Differences in pharmacokinetics of TRC105 (anti-endoglin antibody) when administered as a single agent versus in combination with bevacizumab (Bev)

Background: TRC105 is an anti-endoglin chimeric monoclonal antibody that inhibits angiogenesis and tumor growth and is being studied in randomized Phase 2 trials with Bev. TRC105 is cleared through binding to endoglin expressed on proliferating endothelium when given as a single agent to cancer patients (Spencer et al, ASCO 2012). Preclinical data indicate that endoglin expression is increased in response to VEGF targeted treatment, and increased endoglin expression in response to Bev may increase the clearance of TRC105 when administered in combination to cancer patients.

Methods: Patients (pts) with solid tumors (ST) or ovarian cancer (OC) received 10 mg/kg/wk TRC105 as a single agent, and additional patients with ST (primarily ovarian and colorectal) received 10 mg/kg/wk TRC105 with Bev. Peak and trough levels were assessed by ELISA in 39 patients who received TRC105 alone and compared to that of 35 patients (largely Bev refractory) who received TRC105 and Bev. Pts administered TRC105 and Bev were considered a population sub-group and treated as a covariate. A population pharmacokinetic model of TRC105 disposition was built using rich sampling from the ST trial, with sparse data from OC and TRC105+Bev included in the base model. A two-compartment model with nonlinear elimination best fit the data, utilizing Michaelis-Menten parameters for saturable clearance.

Results: TRC105 peak and trough concentrations exceeded target serum concentrations of TRC105 known to saturate endoglin receptors in all pts dosed with 10 mg/kg/wk of TRC105 with and without Bev. The PK of TRC105 given with Bev had mean predicted (following 10,000 simulations) parameters of volume of distribution in the central compartment (VC), VMAX, and KM that were increased compared to population estimated parameters of TRC105 given as a single agent [VC= 44.5±2 (SE) (mL/kg) Pop mean estimate vs. 68.8±4 (mL/kg) Bev predicted; VMAX = 92.6±16 (μg/hr) vs. 297.5±40 (μg/hr) predicted, and KM= 5.91±2 (μg/mL) vs. 61.6±8.8 (μg/mL)]. All differences were significant (p&lt;0.001). Observable data from patients administered the combination yielded PK parameters that were consistent with increased target-mediated clearance of TRC105 when given with Bev.

Conclusions: Peak and trough TRC105 serum levels exceed target serum concentrations when given at 10 mg/kg/wk as a single agent or with Bev. Central compartment distribution of TRC105 increased when given with Bev, which is consistent with increased endoglin expression on proliferating endothelium following Bev treatment. The maximum rate of elimination (Vmax) also increased, consistent with increased turnover; however the intrinsic clearance ratio of Vmax/Km remained the same, suggesting no change in endoglin turnover efficiency. Future studies will assess whether PK parameters correlate with responses to the combination of TRC105 and Bev in Bev refractory patients.

Citation Format: Shawn D. Spencer, Lee S. Rosen, Michael S. Gordon, Francisco Robert, Daniela Matei, Cody J. Peer, Bonne Adams, Delia Alvarez, Ben K. Seon, Charles P. Theuer, W. Douglas Figg. Differences in pharmacokinetics of TRC105 (anti-endoglin antibody) when administered as a single agent versus in combination with bevacizumab (Bev). [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr CT222. doi:10.1158/1538-7445.AM2014-CT222

The CYP2C19*17 variant is not independently associated with clopidogrel response

BACKGROUND

Cytochrome P450 2C19 (CYP2C19) is the principal enzyme responsible for converting clopidogrel into its active metabolite, and common genetic variants have been identified, most notably CYP2C19*2 and CYP2C19*17, that are believed to alter its activity and expression, respectively.

OBJECTIVE

We evaluated whether the consequences of the CYP2C19*2 and CYP2C19*17 variants on clopidogrel response were independent of each other or genetically linked through linkage disequilibrium (LD).

PATIENTS/METHODS

We genotyped the CYP2C19*2 and CYP2C19*17 variants in 621 members of the Pharmacogenomics of Anti-Platelet Intervention (PAPI) Study and evaluated the effects of these polymorphisms singly and then jointly, taking into account LD, on clopidogrel prodrug level, clopidogrel active metabolite level, and adenosine 5'-diphosphate (ADP)-stimulated platelet aggregation before and after clopidogrel exposure.

RESULTS

The CYP2C19*2 and CYP2C19*17 variants were in LD (|D'| = 1.0; r(2)  = 0.07). In association analyses that did and did not account for the effects of CYP2C19*17, CYP2C19*2 was strongly associated with levels of clopidogrel active metabolite (β = -5.24, P = 3.0 × 10(-9) and β = -5.36, P = 3.3 × 10(-14) , respectively) and posttreatment ADP-stimulated platelet aggregation (β = 7.55, P = 2.9 × 10(-16) and β = 7.51, P = 7.0 × 10(-15) , respectively). In contrast, CYP2C19*17 was marginally associated with clopidogrel active metabolite levels and ADP-stimulated platelet aggregation before (β = 1.57, P = 0.04 and β = -1.98, P = 0.01, respectively) but not after (β = 0.40, P = 0.59 and β = -0.13, P = 0.69, respectively) adjustment for the CYP2C19*2 variant. Stratified analyses of CYP2C19*2/CYP2C19*17 genotype combinations revealed that CYP2C19*2, and not CYP2C19*17, was the primary determinant in altering clopidogrel response.

CONCLUSIONS

Our results suggest that CYP2C19*17 has a small (if any) effect on clopidogrel-related traits and that the observed effect of this variant is due to LD with the CYP2C19*2 loss-of-function variant.

OATP1B1 polymorphism as a determinant of erythromycin disposition

Previous studies have demonstrated that the pharmacokinetic profile of erythromycin, a probe for CYP3A4 activity, is affected by inhibitors or inducers of hepatic solute carriers. We hypothesized that these interactions are mediated by OATP1B1 (gene symbol, SLCO1B1), a polypeptide expressed on the basolateral surface of hepatocytes. Using stably transfected Flp-In T-Rex293 cells, erythromycin was found to be a substrate for OATP1B1*1A (wild type) with a Michaelis-Menten constant of ~13 µmol/l, and that its transport was reduced by ~50% in cells expressing OATP1B1*5 (V174A). Deficiency of the ortholog transporter Oatp1b2 in mice was associated with a 52% decrease in the metabolic rate of erythromycin (P = 0.000043). In line with these observations, in humans the c.521T>C variant in SLCO1B1 (rs4149056), encoding OATP1B1*5, was associated with a decline in erythromycin metabolism (P = 0.0072). These results suggest that impairment of OATP1B1 function can alter erythromycin metabolism, independent of changes in CYP3A4 activity.

Phase I trial of the combination of flavopiridol and imatinib mesylate in patients with Bcr-Abl+ hematological malignancies

PURPOSE

Imatinib is an inhibitor of the Bcr-Abl tyrosine kinase; however, resistance is common. Flavopiridol, a cyclin-dependent kinase (CDK) inhibitor, down-regulates short-lived anti-apoptotic proteins via inhibition of transcription. In preclinical studies, flavopiridol synergizes with imatinib to induce apoptosis. We investigated this novel combination regimen in patients with Bcr-Abl(+) malignancies.

METHODS

In a phase I dose-escalation study, imatinib was administered orally daily, and flavopiridol by 1 h intravenous infusion weekly for 3 weeks every 4 weeks. Adults with chronic myelogenous leukemia or Philadelphia chromosome-positive acute leukemia were eligible. Patients were divided into two strata based on peripheral blood and bone marrow blast counts. The primary objective was to identify the recommended phase II doses for the combination. Correlative pharmacokinetic and pharmacodynamic studies were also performed.

RESULTS

A total of 21 patients received study treatment. Four dose levels were evaluated before the study was closed following the approval of the second-generation Bcr-Abl tyrosine kinase inhibitors (TKIs). Five patients responded, including four sustained responses. Four patients had stable disease. All but one responder, and all patients with stable disease had previously been treated with imatinib. One patient had a complete response sustained for 30 months. Changes in expression of phospho-Bcr/Abl, -Stat5, and Mcl-1 were monitored. No major pharmacokinetic interaction was observed.

CONCLUSIONS

This is the first study to evaluate the combination of a CDK inhibitor and a TKI in humans. The combination of flavopiridol and imatinib is tolerable and produces encouraging responses, including in some patients with imatinib-resistant disease.

Effect of ABCC2 (MRP2) transport function on erythromycin metabolism

The macrolide antiobiotic erythromycin undergoes extensive hepatic metabolism and is commonly used as a probe for cytochrome P450 (CYP) 3A4 activity. By means of a transporter screen, erythromycin was identified as a substrate for the transporter ABCC2 (MRP2) and its murine ortholog, Abcc2. Because these proteins are highly expressed on the biliary surface of hepatocytes, we hypothesized that impaired Abcc2 function may influence the rate of hepatobiliary excretion and thereby enhance erythromycin metabolism. Using Abcc2 knockout mice, we found that Abcc2 deficiency was associated with a significant increase in erythromycin metabolism, whereas murine Cyp3a protein expression and microsomal Cyp3a activity were not affected. Next, in a cohort of 108 human subjects, we observed that homozygosity for a common reduced-function variant in ABCC2 (rs717620) was also linked to an increase in erythromycin metabolism but was not correlated with the clearance of midazolam. These results suggest that impaired ABCC2 function can alter erythromycin metabolism, independent of changes in CYP3A4 activity.

Finasteride metabolism and pharmacogenetics: new approaches to personalized prevention of prostate cancer

Incidences of prostate cancer in most countries are increasing owing to better detection methods; however, prevention with the use of finasteride, a very effective steroid 5α-reductase type II inhibitor, has been met with mixed success. A wide interindividual variation in response exists and is thought to be due to heritable factors. This article summarizes the literature that attempts to elucidate the molecular mechanisms of finasteride in terms of its metabolism, excretion and interaction with endogenous steroid molecules. We describe previously reported genetic variations of steroid-metabolizing genes and their potential association with finasteride efficacy. Based on the literature, we outline directions of research that may contribute to understanding the interindividual variation in finasteride prevention and to the future development of personalized medicine.

A pharmacogenetic study of docetaxel and thalidomide in patients with castration-resistant prostate cancer using the DMET genotyping platform

The anticancer agent docetaxel shows significant inter-individual variation in its pharmacokinetic and toxicity profile. Thalidomide is an active anticancer agent and also shows wide pharmacological variation. Past pharmacogenetic research has not explained this variation. Patients with prostate cancer enrolled in a randomized phase II trial using docetaxel and thalidomide versus docetaxel alone were genotyped using the Affymetrix DMET 1.0 platform, which tests for 1256 genetic variations in 170 drug disposition genes. Genetic polymorphisms were analyzed for associations with clinical response and toxicity. In all, 10 single-nucleotide polymorphisms (SNPs) in three genes were potentially associated with response to therapy: peroxisome proliferator-activated receptor-delta (PPAR-delta), sulfotransferase family, cytosolic, 1C, member 2 (SULT1C2) and carbohydrate (chondroitin 6) sulfotransferase 3 (CHST3). In addition, 11 SNPs in eight genes were associated with toxicities to treatment: spastic paraplegia 7 (pure and complicated autosomal recessive) (SPG7), CHST3, cytochrome P450, family 2, subfamily D, polypeptide 6 (CYP2D6), N-acetyltransferase 2 (arylamine N-acetyltransferase) (NAT2), ATP-binding cassette, sub-family C (CFTR/MRP), member 6 (ABCC6), ATPase, Cu++ transporting, alpha polypeptide (ATP7A), cytochrome P450, family 4, subfamily B, polypeptide 1 (CYP4B1) and solute carrier family 10 (sodium/bile acid cotransporter family), member 2 (SLC10A2). Genotyping results between drug metabolizing enzymes and transporters (DMET) and direct sequencing showed >96% of concordance. These findings highlight the role that non-CYP450 metabolizing enzymes and transporters may have in the pharmacology of docetaxel and thalidomide.

Modulation of erlotinib pharmacokinetics in mice by a novel cytochrome P450 3A4 inhibitor, BAS 100

Administration of BAS 100, a novel mechanism-based CYP3A4 inhibitor isolated from grapefruit juice, resulted in a 2.1-fold increase in erlotinib exposure following oral administration to wild-type and humanised CYP3A4 transgenic mice. This study illustrates the potential of BAS 100 to increase the low and variable oral bioavailability of erlotinib in cancer patients.

Variants in the SLCO1B3 Gene: Interethnic Distribution and Association with Paclitaxel Pharmacokinetics

To explore retrospectively the relationships between paclitaxel pharmacokinetics and three known, non-synonymous single-nucleotide polymorphisms (SNPs) in SLCO1B3, the gene encoding organic anion transporting polypeptide (OATP)1B3. Accumulation of [(3)H]paclitaxel was studied in Xenopus laevis oocytes injected with cRNA of Oatp1b2, OATP1A2, OATP1B1, OATP1B3, OAT1, OAT3, OCT1, and NTCP. The 334T>G (Ser112Ala), 699G>A (Met233Ile), and 1564G>T (Gly522Cys) loci of SLCO1B3 were screened in 475 individuals from five ethnic groups and 90 European Caucasian cancer patients treated with paclitaxel. Only OATP1B3 was capable of transporting paclitaxel to a significant extent (P=0.003). The 334T>G and 699G>A SNPs were less common in the African-American and Ghanaian populations (P<0.000001). Paclitaxel pharmacokinetics were not associated with the studied SNPs or haplotypes (P>0.3). The studied SNPs in SLCO1B3 appear to play a limited role in the disposition of paclitaxel, although their clinical significance in other ethnic populations remains to be investigated.

Medroxyprogesterone acetate elevation of Nm23-H1 metastasis suppressor expression in hormone receptor-negative breast cancer

BACKGROUND

Reestablishment of metastasis suppressor gene expression may constitute a therapeutic strategy for high-risk breast cancer patients. We previously showed that medroxyprogesterone acetate (MPA), a progestin that has been tested as treatment for advanced breast cancer, elevates expression of the Nm23-H1 metastasis suppressor gene in hormone receptor-negative metastatic human breast carcinoma cell lines in vitro via a glucocorticoid receptor-based mechanism. Here, we tested whether MPA treatment inhibits metastatic colonization of a hormone receptor-negative breast cancer cell line in vivo.

METHODS

We tested the soft-agar colony-forming efficiency of untransfected MDA-MB-231T human breast carcinoma cells and MDA-MB-231T cells transfected with antisense Nm23-H1 in the presence and absence of MPA. Pharmacokinetic studies were used to establish dose and injection schedules that led to MPA serum levels in mice similar to those achievable in humans. For in vivo studies, nude mice were injected intravenously with MDA-MB-231T cells. After 4 weeks, mice were randomized to control or MPA arms. Endpoints included incidence, number, and size of gross pulmonary metastases; Nm23-H1 protein expression in gross metastases; and side effects. All statistical tests were two-sided.

RESULTS

MPA reduced colony formation of MDA-MB-231T cells by 40%-50% but had no effect on colony formation of Nm23-H1 antisense transfectants. Metastases developed in 100% (95% confidence interval [CI] = 78% to 100% and 77% to 100%, respectively) of control mice injected with MDA-MB-231T cells. In two independent experiments, only 73% (95% CI = 45% to 92%) and 64% (95% CI = 35% to 87%) of mice injected with 2 mg of MPA developed metastases. Mice injected with 2 mg of MPA showed reductions in the mean numbers, per mouse, of all metastases and of large (>3 mm) metastases (P = .04 and .013, respectively). Nm23-H1 was expressed at high levels in 43% of pulmonary metastases in MPA-treated mice but only 13% of metastases in untreated mice. Mice receiving at least 1-mg doses of MPA gained more weight than control-treated mice but exhibited no bone density alterations or abnormal mammary fat pad histology.

CONCLUSION

Our preclinical results show that MPA appears to elevate Nm23-H1 metastasis suppressor gene expression, thereby reducing metastatic colonization. The data suggest a new use for an old agent in a molecularly defined subset of breast cancer patients.

Antimyeloma activity of two novel N-substituted and tetraflourinated thalidomide analogs

Thalidomide alone or in combination with steroids has significant activity in multiple myeloma (MM). However, given its teratogenic potential, analogs have been synthesized, retaining the anti-MM activity without these side effects. We examined the anti-MM activity of two thalidomide analogs, CPS11 and CPS49. Direct cytotoxicity of the drugs on myeloma cell lines and patient myeloma cells was examined using thymidine uptake. Tumor cell apoptosis was evaluated by flow cytometry as well as Western blotting for caspase and PARP cleavage. Cellular signaling events were examined by immunoblotting for phosphorylated proteins. Both drugs inhibit proliferation of several MM cell lines sensitive and resistant to conventional therapies. They decrease secretion of IL-6, IGF, and VEGF by marrow stromal cells. Importantly, they inhibit proliferation of MM cells adherent to stromal cells. These drugs induce caspase-mediated apoptosis in MM cell lines, as well as patient MM cells. They inhibit the PI3K/Akt and JAK/STAT (signal transducers and activators of transcription) pathways in MM cells and are antiangiogenic in matrigel-based assays. CPS11 and CPS49 have potent antimyeloma activity and can overcome protective effects of the tumor microenvironment. They have potent antiangiogenic activity and direct effect on bone marrow stroma. These encouraging preclinical data provide the basis for further evaluation in the clinic.

Micellar paclitaxel improves severe psoriasis in a prospective phase II pilot study

BACKGROUND

Taxanes (eg, paclitaxel) are chemotherapeutic agents that have antiproliferative, antiangiogenic, and antiinflammatory properties.

OBJECTIVE

We sought to explore the safety and efficacy of paclitaxel in individuals with severe psoriasis.

METHODS

An open-label, prospective, phase II pilot study was conducted at the National Institutes of Health Clinical Center, a federal government medical research facility, in Bethesda, Maryland. Twelve patients with severe psoriasis, as defined by a baseline Psoriasis Area and Severity Index (PASI) score of >or= 20), were studied. Initially, patients received 6 intravenous infusions of micellar paclitaxel, 75 mg/m(2), at 4-week intervals (stage I). Later patients received 9 intravenous infusions of micellar paclitaxel at 2-week intervals (37.5 mg/m(2) for 3 doses followed by 50 mg/m(2) for six additional doses) (stage II). The primary end point was the percent change in the PASI from week 0 to week 24 in stage I and from week 0 to week 20 in stage II.

RESULTS

In stage I, all 5 patients improved (mean = 59.7% decrease in PASI, median = 59.6%, range: 40.3%-79.2%). Four of the 7 patients completed stage II and all of these patients improved (mean = 45.9% decrease in PASI, median = 45.0%, range: 14.6%-79.1%). Micellar paclitaxel was well tolerated by most patients.

CONCLUSIONS

Micellar paclitaxel demonstrates therapeutic activity in patients with severe psoriasis.

Microarray gene expression profiling of angiogenesis inhibitors using the rat aortic ring assay

The rat aortic ring assay has been previously described as a useful ex vivo model for analyzing the biological activity of various inhibitors of angiogenesis. Rat aortic rings are exposed to antiangiogenic agents for a five-day incubation period. Then, the degree of microvessel outgrowth from the rings is analyzed and quantified. In contrast to most in vitro angiogenesis assays, the rat aortic ring model provides a unique microenvironment to evaluate the interaction of various cell types and biological factors for their influence on angiogenesis. Microarray analysis is an accepted method for the evaluation of gene expression profiles and can be used to better understand changes in gene expression that occur when rat aortic rings are exposed to a particular biological agent. Here we describe a method of using microarray technology to evaluate the modulation of gene expression in angiogenesis using the rat aortic ring assay.

Thalidomide, an antiangiogenic agent with clinical activity in cancer

Despite the teratogenic past of thalidomide, there is recent evidence indicating the drug's efficacy in the management of various diseases from immune disorders to cancers. The history, pharmacodynamic and pharmacokinetic properties of thalidomide in the clinic are discussed in this review article.

Approaches to preclinical screening of antiangiogenic agents

Angiogenesis, or new blood vessel growth, is essential for the growth, invasion, and metastasis of solid tumors. The inhibition of this process, or antiangiogenesis, is a promising new therapeutic anticancer strategy. Several antiangiogenic compounds are currently in preclinical or clinical development for the treatment of cancer. However, the challenge for the discovery and characterization of antiangiogenic targets remains in developing efficient in vitro or in vivo preclinical angiogenesis screening assays to assess and compare antiangiogenic activity. Several semiquantitative or quantitative angiogenesis assays exist, including in vitro endothelial cell systems and ex vivo or in vivo neovascularization models utilizing mouse, rat, or human tissues. We describe the more common and cost-effective angiogenesis assays currently in use, summarizing their unique advantages and disadvantages. Since angiogenesis inhibition is a novel therapeutic modality towards controlling solid tumors, antiangiogenic drug development underlines the importance in describing, standardizing, and developing quantitative screening assays for the next generation of antiangiogenic agents.

The Hsp90 inhibitor geldanamycin selectively sensitizes Bcr-Abl-expressing leukemia cells to cytotoxic chemotherapy

The Bcr-Abl fusion protein drives leukemogenesis and can render leukemia cells resistant to conventional chemotherapy. Geldanamycin (GA), a drug which destabilizes Hsp90-associated proteins, depletes cells of Bcr-Abl, an Hsp90 client, but not of Abl. Both HL60 cells transfected with Bcr-Abl and naturally Ph1-positive K562 leukemia cells are resistant to most cytotoxic drugs, but were found to be sensitive to GA. Furthermore, GA sensitized Bcr-Abl-expressing cells to doxorubicin (DOX) and paclitaxel (PTX). In contrast, in parental HL60 cells, 90 nM GA inhibited PARP cleavage, nuclear fragmentation, and cell death caused by 500 ng/ml DOX. Like GA, STI 571 (an inhibitor of the Abl kinase) sensitized Bcr-Abl-expressing cells to DOX. Unlike GA, STI 571 did not antagonize the cytotoxic effects of DOX in parental HL60 cells. These results indicate that sensitization of Bcr-Abl-expressing cells, but not desensitization of HL60 cells, depends on inhibition of Bcr-Abl. Thus, GA differentially affects leukemia cells depending on their Bcr-Abl expression and selectively increases apoptosis in Bcr-Abl-expressing cells.

A Phase I study of infusional vinblastine in combination with the P-glycoprotein antagonist PSC 833 (valspodar)

BACKGROUND

PSC 833 is a second-generation P-glycoprotein (Pgp) antagonist developed to reverse multidrug resistance (MDR). The authors conducted a Phase I study of orally administered PSC 833 in combination with vinblastine administered as a 5-day continuous infusion.

METHODS

Seventy-nine patients with advanced malignant disease were enrolled in the trial and treated with escalating doses of PSC 833. Pharmacokinetic interactions between PSC 833 and vinblastine were anticipated. Accordingly, when dose limiting toxicities were observed, the dose of vinblastine was reduced as PSC 833 was escalated. Three schedules and two formulations of PSC 833 were used in the study.

RESULTS

The maximum tolerated doses of PSC 833 were 12.5 mg/kg orally every 12 hours for 8 days for the liquid formulation in combination with 0.9 mg/m(2) per day vinblastine as a continuous intravenous infusion (CIV) for 5 days; and 4 mg/kg orally every 6 hours for 8 days for the microemulsion formulation in combination with 0.6 mg/m(2) per day vinblastine CIV for 5 days. The principal toxicities for PSC 833 were ataxia and paresthesias and for the combination, constipation, fever. and neutropenia. Increased oral bioavailability and increased peak and trough concentrations were observed with the microemulsion formulation. Significant interpatient variability in pharmacokinetic parameters was observed. Ten patients studied at the MTD for PSC 833 (4 mg/kg orally every 6 hours for 8 days) had inhibition of rhodamine efflux from CD56 positive peripheral lymphocytes as a surrogate for Pgp antagonism. Among 43 evaluable patients with clear cell carcinoma of the kidney, 3 patients had complete responses, and 1 patient had a partial response.

CONCLUSIONS

PSC 833 in combination with vinblastine can be administered safely to patients provided the vinblastine dose is adjusted for pharmacokinetic interactions. The high interpatient variability is a significant confounding factor. Surrogate studies with CD56 positive cells suggest that Pgp inhibition in the clinical setting is achievable. Improved methods for predicting pharmacokinetic interactions should improve future studies.

The androgen receptor gene and its influence on the development and progression of prostate cancer

Prostate adenocarcinoma has the highest incidence of any malignancy and is the second leading cause of cancer-related deaths in men in industrialized countries. The development and progression of prostate cancer are dependent on testosterone and dihydrotestosterone; the androgen receptor is the vehicle through which these androgens exert their regulation on prostate cellular proliferation and differentiation. As a result, much effort has been devoted to elucidating the role of the androgen receptor in prostate cancer. The CAG and GGN trinucleotide repeats in exon 1 of the androgen receptor gene have been linked to prostate cancer risk and progression in some studies. Also, androgen receptor gene amplification may be a mechanism of prostate cancer cell adaptation to hormonal therapy. In addition, androgen receptor somatic mutations can result in receptors that have altered binding specificity when compared with wild-type receptors and heightened affinity for hormones other than testosterone and dihydrotestosterone. Gene amplification and somatic mutations, coupled with the fact that various growth factors have been shown to stimulate androgen receptor activity independently of androgens, may enable prostate cancer cells to grow despite testicular-androgen ablation. Unfortunately, current medical therapy for metastatic prostate cancer is deficient, hormone-refractory prostate cancer is a major obstacle in treatment, and, as a result, prostate cancer mortality is still significant. Further study of the function of the androgen receptor will offer a better understanding of prostate cancer pathogenesis and progression, aiding the development of more effective treatments for this disease.

Alendronate does not interfere with 99mTc-methylene diphosphonate bone scanning

Several studies have found that administration of etidronate results in competitive interference with 99mTc-labeled bone scanning reagents. In contrast, in other studies this problem was not encountered with other bisphosphonates.

METHODS

We prospectively studied 9 patients with hormone-refractory prostate cancer. 99mTc-methylene diphosphonate (MDP) bone scanning was performed before they received alendronate, and scanning was repeated a mean of 16.6 d afterward, when the patients had been receiving 40 mg alendronate daily for a mean of 6 d. In addition, 7 patients who underwent delayed scanning when they had been receiving alendronate for a mean of 111 d were also restudied. Quantitative whole-body bone scanning was performed, and radioactivity deposited in the bone metastasis was determined using region-of-interest analysis.

RESULTS

A <6% increase in whole-body retention of 99mTc-MDP was seen on the initial postalendronate scan compared with the baseline scan. No significant differences in activity were seen in the bone lesion evaluated on the baseline and initial postalendronate studies. The delayed postalendronate scan generally showed similar or higher tracer accumulation compared with the baseline scan.

CONCLUSION

Alendronate did not competitively inhibit uptake of 99mTc-MDP in the skeleton or tumor metastasis. Use of alendronate before bone scanning is unlikely to result in decreased detection of lesions or falsely decreased 99mTc-MDP activity at metastatic bone tumor sites.

Quantitative determination of perifosine, a novel alkylphosphocholine anticancer agent, in human plasma by reversed-phase liquid chromatography-electrospray mass spectrometry

A sensitive and selective reversed-phase LC-ESI-MS method to quantitate perifosine in human plasma was developed and validated. Sample preparation utilized simple acetonitrile precipitation without an evaporation step. With a Develosil UG-30 column (10 x 4 mm I.D.), perifosine and the internal standard hexadecylphosphocholine were baseline separated at retention times of 2.2 and 1.1 min, respectively. The mobile phase consisted of eluent A, 95% 9 mM ammonium formate (pH 8) in acetonitrile-eluent B, 95% acetonitrile in 9 mM ammonium formate (pH 8) (A-B, 40:60, v/v), and the flow-rate was 0.5 ml/min. The detection utilized selected ion monitoring in the positive-mode at m/z 462.4 and 408.4 for the protonated molecular ions of perifosine and the internal standard, respectively. The lower limit of quantitation of perifosine was 4 ng/ml in human plasma, and good linearity was observed in the 4-2,000 ng/ml range fitted by linear regression with 1/x weight. The total LC-MS run time was 5 min. The validated LC-MS assay was applied to measure perifosine plasma concentrations from patients enrolled on a phase I clinical trial for pharmacokinetic/pharmacodynamic analyses.

A phase I dose escalation and bioavailability study of oral sodium phenylbutyrate in patients with refractory solid tumor malignancies

PURPOSE

Phenylbutyrate (PB) is an aromatic fatty acid with multiple mechanisms of action including histone deacetylase inhibition. Preclinically, PB demonstrates both cytotoxic and differentiating effects at a concentration of 0.5 mM. We conducted a Phase I trial of p.o. PB patients with refractory solid tumor malignancies to evaluate toxicity, pharmacokinetic parameters, and feasibility of p.o. administration.

EXPERIMENTAL DESIGN

Twenty-eight patients with refractory solid tumor malignancies were enrolled on this dose-escalation to maximally tolerated dose trial. Five dose levels of PB were studied: 9 g/day (n = 4), 18 g/day (n = 4), 27 g/day (n = 4), 36 g/day (n = 12), and 45 g/day (n = 4). Pharmacokinetic studies were performed and included an p.o. bioavailability determination. Compliance data were also collected.

RESULTS

The recommended Phase II dose is 27 g/day. Overall the drug was well tolerated with the most common toxicities being grade 1-2 dyspepsia and fatigue. Nonoverlapping dose-limiting toxicities of nausea/vomiting and hypocalcemia were seen at 36 g/day. The p.o. bioavailability of PB was 78% for all dose levels, and the biologically active concentration of 0.5 mM was achieved at all dose levels. Compliance was excellent with 93.5% of all possible doses taken. No partial remission or complete remission was seen, but 7 patients had stable disease for more than 6 months while on the drug.

CONCLUSIONS

PB (p.o.) is well tolerated and achieves the concentration in vivo that has been shown to have biological activity in vitro. PB may have a role as a cytostatic agent and should be additionally explored in combination with cytotoxics and other novel drugs.

A randomized phase II trial of docetaxel (taxotere) plus thalidomide in androgen-independent prostate cancer

New therapeutic alternatives are needed to improve outcomes in patients with androgen-independent prostate cancer (AIPC). For several years, researchers at the National Cancer Institute have been interested in elucidating the importance of angiogenesis in the pathogenesis of prostate cancer and in identifying inhibitors of this process. Thalidomide has been shown to inhibit the ability of tumors to recruit new blood vessels. In a recent phase II trial of thalidomide in AIPC, 28% of patients achieved a prostate-specific antigen (PSA) decrease of >40%. The taxane docetaxel also produces PSA and measurable disease responses when used as monotherapy or as a component of combination chemotherapy for AIPC. Thus, based on the single-agent activity of thalidomide and docetaxel, we initiated a randomized phase II study of weekly docetaxel with or without thalidomide, 200 mg at bedtime, in patients with chemotherapy-naive metastatic AIPC. Docetaxel, 30 mg/m(2) intravenously, was administered every 7 days for 3 weeks, followed by a 1-week rest period. Both regimens have been well tolerated among the first 59 treated patients, with a near absence of grade (3/4) myelosuppression. Fatigue, hyperglycemia, and pulmonary toxicity were seen in both groups. Thrombotic events have been seen in the combination arm. Thirty-five percent (6 of 17) of the patients receiving docetaxel alone and 53% (19 of 36) of those receiving docetaxel and thalidomide have had a PSA decrease of at least 50%. Combining a cytotoxic agent with an angiogenesis inhibitor is a promising area of investigation for prostate cancer management.

Thalidomide neuropathy in patients treated for metastatic prostate cancer

We prospectively evaluated thalidomide-induced neuropathy using electrodiagnostic studies. Sixty-seven men with metastatic androgen-independent prostate cancer in an open-label trial of oral thalidomide underwent neurologic examinations and nerve conduction studies (NCS) prior to and at 3-month intervals during treatment. NCS included recording of sensory nerve action potentials (SNAPs) from median, radial, ulnar, and sural nerves. SNAP amplitudes for each nerve were expressed as the percentage of its baseline, and the mean of the four was termed the SNAP index. A 40% decline in the SNAP index was considered clinically significant. Thalidomide was discontinued in 55 patients for lack of therapeutic response. Of 67 patients initially enrolled, 24 remained on thalidomide for 3 months, 8 remained at 6 months, and 3 remained at 9 months. Six patients developed neuropathy. Clinical symptoms and a decline in the SNAP index occurred concurrently. Older age and cumulative dose were possible contributing factors. Neuropathy may thus be a common complication of thalidomide in older patients. The SNAP index can be used to monitor peripheral neuropathy, but not for early detection.

Impact of the putative differentiating agent sodium phenylbutyrate on myelodysplastic syndromes and acute myeloid leukemia

Sodium phenylbutyrate (PB) is an aromatic fatty acid with cytostatic and differentiating activity against malignant myeloid cells (ID(50), 1-2 mM). Higher doses induce apoptosis. Patients with myelodysplasia (n = 11) and acute myeloid leukemia (n = 16) were treated with PB as a 7-day continuous infusion repeated every 28 days in a Phase I dose escalation study. The maximum tolerated dose was 375 mg/kg/day; higher doses led to dose-limiting reversible neurocortical toxicity. At the maximum tolerated dose, PB was extremely well tolerated, with no significant toxicities; median steady-state plasma concentration at this dose was 0.29 +/- 0.16 mM. Although no patients achieved complete or partial remission, four patients achieved hematological improvement (neutrophils in three, platelet transfusion-independence in one). Other patients developed transient increases in neutrophils or platelets and decrements in circulating blasts. Monitoring of the percentage of clonal cells using centromere fluorescence in situ hybridization over the course of PB administration showed that hematopoiesis remained clonal. Hematological response was often associated with increases in both colony-forming units-granulocyte-macrophage and leukemic colony-forming units. PB administration was also associated with increases in fetal erythrocytes. These data document the safety of continuous infusion PB and provide preliminary evidence of clinical activity in patients with myeloid malignancies.

A randomized phase II trial of thalidomide, an angiogenesis inhibitor, in patients with androgen-independent prostate cancer

PURPOSE

Thalidomide is a potent teratogen that causes dysmelia in humans. Recently, in vitro data suggested that it inhibits angiogenesis. Prostate cancer is dependent on the recruitment of new blood vessels to grow and metastasize. Based on those data, we initiated a Phase II trial of thalidomide in patients with metastatic androgen-independent prostate cancer.

EXPERIMENTAL DESIGN

This was an open-label, randomized Phase II study. Thalidomide was administered either at a dose of 200 mg/day (low-dose arm) or at an initial dose of 200 mg/day that escalated to 1200 mg/day (high-dose arm).

RESULTS

A total of 63 patients were enrolled onto the study (50 patients on the low-dose arm and 13 patients on the high-dose arm). Serum prostate-specific antigen (PSA) decline of > or = 50% was noted in 18% of patients on the low-dose arm and in none of the patients on the high-dose arm. Four patients were maintained for > 150 days. The most prevalent complications were constipation, fatigue, neurocortical, and neurosensory.

CONCLUSION

Thalidomide, an antiangiogenesis agent, has some activity in patients with metastatic prostate cancer who have failed multiple therapies. A total of 27% of all patients had a decline in PSA of > or = 40%, often associated with an improvement of clinical symptoms. Because our preclinical studies had shown that thalidomide increases PSA secretion, we believe that the magnitude of PSA decline seen in our trial justifies further study.

Protein binding alters the activity of suramin, carboxyamidotriazole, and UCN-01 in an ex vivo rat aortic ring angiogenesis assay

Angiogenesis inhibitors are currently in clinical development for cancer. These agents pose unique developmental challenges: (a) determining maximum biological doses versus maximum tolerated doses; (b) defining response criteria other than objective tumor responses; and (c) defining safe regimens for prolonged, chronic administration. The current in vitro angiogenesis assays used in the screening and preclinical development of antiangiogenic agents each have their own advantages and disadvantages, yet all seem to underestimate the importance and impact of in vivo protein-drug interactions. We have developed a human serum rat aortic ring angiogenesis bioassay that highlights protein binding concerns using three anticancer agents that have documented antiangiogenic activity: suramin, carboxyamidotriazole, and 7-hydroxystaurosporine. We have determined that the bioassay concentrations of suramin (100 microg/ml) and 7-hydroxystaurosporine (> 1 microg/ml), but not carboxyamidotriazole (> or = 60 microg/ml), that inhibit microvessel formation are consistent with target plasma levels achievable in the clinic. We conclude that assays such as the human serum rat aortic ring bioassay may prove useful in predicting the concentrations of protein-bound antiangiogenic agents required for free fraction biological activity.

A phase I trial of carboxyamido-triazole and paclitaxel for relapsed solid tumors: potential efficacy of the combination and demonstration of pharmacokinetic interaction

PURPOSE

Preclinical and clinical investigation of the combination of the antiangiogenesis/anti-invasion agent carboxyamido-triazole (CAI) administered with the cytotoxic agent paclitaxel (PAX).

EXPERIMENTAL DESIGN

Colony-forming assays were used to test the activity of CAI plus PAX on A2780 human ovarian cancer. The sequence of CAI followed by PAX (CAI>Pax) was modeled in nude mice to test for potential additive toxicity. The Phase I clinical dose escalation schema tested p.o. administered CAI in PEG-400 (50-100 mg/m(2)) or micronized CAI (250 mg/m(2)) for 8 days followed by a 3-h infusion of PAX (110-250 mg/m(2)) every 21 days. Patients were assessed for toxicity, pharmacokinetics of CAI and PAX, and disease outcome.

RESULTS

In preclinical studies, CAI>Pax was additive in A2780 human ovarian cancer cell lines when CAI (1 or 5 microM) preceded subtherapeutic doses of PAX. CAI did not reverse PAX resistance and collateral resistance to CAI was documented in PAX-resistant cells. CAI>PAX administration had no overt additive toxicity in nude mice. Thirty-nine patients were treated on a dose-escalation Phase I trial using daily oral CAI for 8 days followed by the PAX infusion. Pharmacokinetic analysis revealed that PAX caused an acute increase in circulating CAI concentrations in a dose-dependent fashion. No additive or cumulative toxicity was observed, and grade 3 nonhematological toxicity was rare. Three partial responses and two minor responses were observed.

CONCLUSIONS

The sequential combination of CAI and PAX is well tolerated, and the activity observed suggests that further study of the combination is warranted.

The P-glycoprotein antagonist PSC 833 increases the plasma concentrations of 6alpha-hydroxypaclitaxel, a major metabolite of paclitaxel

PURPOSE

Overexpression of P-glycoprotein (Pgp) is one mechanism of drug resistance in cancer chemotherapy. A Phase I trial was conducted using PSC 833, a Pgp antagonist, in combination with paclitaxel in patients with refractory cancer. The objective of this study was to assess the effect of PSC 833 on the metabolism of paclitaxel and characterize the differences in 6alpha-hydroxypaclitaxel pharmacokinetics. In addition, we examined the possibility of enhanced cytotoxicity of paclitaxel by the coexistence of 6alpha-hydroxypaclitaxel.

EXPERIMENTAL DESIGN

Patients received paclitaxel 35 mg/m(2)/day by continuous intravenous infusion (CIVI) x 4 days without PSC 833 in cycle 1 and escalating doses of paclitaxel (13.1, 17.5, or 21.3 mg/m(2)/day CIVI x 4 days) with 5 mg/kg PSC 833 by mouth every 6 h x 7 days in cycle 2. Plasma samples were analyzed for both paclitaxel and its major metabolite with high-performance liquid chromatography methods. Using human liver microsomes, we studied the effect of PSC 833 on the metabolism of paclitaxel. In addition, the in vitro cytotoxicity of 6alpha-hydroxypaclitaxel alone and in combination with paclitaxel was evaluated.

RESULTS

Twenty-one of 22 patients had a metabolite peak (6alpha-hydroxypaclitaxel) observed in the chromatogram of plasma samples from cycle 2 when they received paclitaxel in combination with PSC 833. This metabolite was not detectable in plasma obtained during the first cycle when they received paclitaxel without PSC 833. During cycle 2, the mean concentrations of 6alpha-hydroxypaclitaxel and paclitaxel were 0.10 +/- 0.074 and 0.079 +/- 0.041 microg/ml, respectively. A moderate association was observed between total bilirubin and 6alpha-hydroxypaclitaxel concentrations (P = 0.015, r = 0.52; n = 21). Human liver microsome experiments showed that a PSC 833 concentration as high as 10 microM did not affect the production of 6alpha-hydroxypaclitaxel. Paclitaxel cytotoxicity in HL60 and K562 human leukemia cells was increased in the presence of noncytotoxic concentrations of 6alpha-hydroxypaclitaxel.

CONCLUSIONS

PSC 833 increases the plasma concentration of 6alpha-hydroxypaclitaxel during paclitaxel therapy. Inhibition of cytochrome P-450 3A4 by PSC 833 may explain this in part, although other mechanisms cannot be excluded.

Reversible sideroblastic anemia associated with the tetracycline analogue COL-3

Eight of 35 patients with cancer receiving COL-3, a tetracycline derivative with antiangiogenic properties, developed anemia while on treatment. All of these patients were enrolled on an approved Phase I clinical trial at the National Cancer Institute. Three of these patients had bone marrow examinations that revealed ringed sideroblasts. This paper describes these cases. Am. J. Hematol. 67:51-53, 2001. Published 2001 Wiley-Liss, Inc.

Phase I trial of 72-hour continuous infusion UCN-01 in patients with refractory neoplasms

PURPOSE

To define the maximum tolerated dose (MTD) and dose-limiting toxicity (DLT) of the novel protein kinase inhibitor, UCN-01 (7-hydroxystaurosporine), administered as a 72-hour continuous intravenous infusion (CIV).

PATIENTS AND METHODS

Forty-seven patients with refractory neoplasms received UCN-01 during this phase I trial. Total, free plasma, and salivary concentrations were determined; the latter were used to address the influence of plasma protein binding on peripheral tissue distribution. The phosphorylation state of the protein kinase C (PKC) substrate alpha-adducin and the abrogation of DNA damage checkpoint also were assessed.

RESULTS

The recommended phase II dose of UCN-01 as a 72-hour CIV is 42.5 mg/m(2)/d for 3 days. Avid plasma protein binding of UCN-01, as measured during the trial, dictated a change in dose escalation and administration schedules. Therefore, nine patients received drug on the initial 2-week schedule, and 38 received drug on the recommended 4-week schedule. DLTs at 53 mg/m(2)/d for 3 days included hyperglycemia with resultant metabolic acidosis, pulmonary dysfunction, nausea, vomiting, and hypotension. Pharmacokinetic determinations at the recommended dose of 42.5 mg/m(2)/d for 3 days included mean total plasma concentration of 36.4 microM (terminal elimination half-life range, 447 to 1176 hours), steady-state volume of distribution of 9.3 to 14.2 L, and clearances of 0.005 to 0.033 L/h. The mean total salivary concentration was 111 nmol/L of UCN-01. One partial response was observed in a patient with melanoma, and one protracted period ( > 2.5 years) of disease stability was observed in a patient with alk-positive anaplastic large-cell lymphoma. Preliminary evidence suggests UCN-01 modulation of both PKC substrate phosphorylation and the DNA damage-related G(2) checkpoint.

CONCLUSION

UCN-01 can be administered safely as an initial 72-hour CIV with subsequent monthly doses administered as 36-hour infusions.