Frederick H. Hausheer

Feasibility and validity of the Patient Neurotoxicity Questionnaire during taxane chemotherapy in a phase III randomized trial in patients with breast cancer: N-SAS BC 02

GoalsThe aim of the study was to determine the feasibility and validity of a newly developed patient-based instrument—the Patient Neurotoxicity Questionnaire (PNQ)—for grading chemotherapy-induced peripheral neuropathy (CIPN).Patients and methodsWe prospectively collected data from 300 female patients who were treated with taxane chemotherapy for primary breast cancer as part of a national multicenter phase III randomized trial (N-SAS BC 02). We evaluated patient compliance with the PNQ and several validation parameters, including concordance between CIPN grades noted by physicians (National Cancer Institute Common Toxicity Criteria) and patients (PNQ), and the concurrent validity and responsiveness of the PNQ versus the Functional Assessment of Cancer Therapy/Gynecologic Oncology Group-Neurotoxicity (FACT/GOG-Ntx) utilizing data at pre-treatment and before three, five, and seven treatment cycles.Main resultsThe questionnaire completion rate was >90% at all assessments. Evaluation by physicians always resulted in lower neuropathy assessment scores compared with those reported directly by patients (weighted kappa coefficients, 0.02–0.06). Both PNQ sensory and motor scores were significantly correlated with the FACT/GOG-Ntx (r = 0.66 and 0.51, respectively). In the repeated measures analysis of variance model, PNQ grades increased considerably as treatment continued, indicating progressively worsening CIPN over time.ConclusionsThe PNQ has an applicable degree of feasibility and validity, useful for the diagnosis of CIPN as well as for clinical treatment decision-making, where the development of CIPN is a potential treatment-limiting consideration. Physicians underreport and underestimate the severity of CIPN symptoms compared with patients, thereby supporting the importance of assessing patient-reported outcomes using the PNQ.

Comprehensive ab initio quantum mechanical and molecular orbital (MO) analysis of cisplatin: Structure, bonding, charge density, and vibrational frequencies

We carried out an extensive series of ab initio quantum mechanical (QM) calculations using pure effective core potential (ECP) and hybrid Hartree–Fock (HF)/ECP basis sets, including various electron correlation treatments up to the MP4 level on cis‐diamminedichloroplatinum(II), cisplatin, an important anticancer drug. The optimized geometric parameters and vibrational frequencies of cisplatin were compared with the experimental values, and the effects of varying basis sets and correlation (MP level) treatments on the geometric parameters and vibrational frequencies were analyzed. We also present a detailed description of the bonding in cisplatin using qualitative MO analysis to characterize the key intramolecular interactions in cisplatin. The calculated molecular electrostatic potential (MEP), and the electrostatic potential (ESP) charges for cisplatin were used to identify regions of electrophilic and nucleophilic character. The charge density and the Laplacian of charge density of cisplatin were calculated to determine its bonding relationships. Using basis set performance, we identified two hybrid basis sets (HF/6‐311G* and MP2/6‐311G*) as basis sets of choice for studying cisplatins molecular properties. Furthermore, we recommend a hybrid ECP/HF approach with electron correlation for the most accurate physicochemical and electronic description of cisplatin and related compounds. ©1999 John Wiley & Sons, Inc. J Comput Chem 20: 365–382, 1999

Diagnosis and treatment of malignant pleural effusion

SummaryPleural effusion is a common and important complication of malignancy which may at times be difficult to diagnose or treat. Its well recognized association with numerous diseases plus the limitations of our usual diagnostic tests may occasionally cause difficulty. In the oncology patient there are a number of common medical problems associated with the development of pleural effusion which frequently coexist with the malignancy. Pleural effusion may be a presenting or late sign of cancer, and when recurrent can be a vexing symptomatic problem. Fortunately, an increasing number of effective diagnostic and therapeutic modalities are available which, when judiciously applied, facilitate our approach.Pleural effusion is a common and important complication of malignancy which may at times be difficult to diagnose or treat. Its well recognized association with numerous diseases plus the limitations of our usual diagnostic tests may occasionally cause difficulty. In the oncology patient there are a number of common medical problems associated with the development of pleural effusion which frequently coexist with the malignancy. Pleural effusion may be a presenting or late sign of cancer, and when recurrent can be a vexing symptomatic problem. Fortunately, an increasing number of effective diagnostic and therapeutic modalities are available which, when judiciously applied, facilitate our approach.

Mechanistic study of BNP7787-mediated cisplatin nephroprotection: modulation of gamma-glutamyl transpeptidase

PurposeThe mechanisms for cisplatin-induced renal cell injury have been the focus of intense investigation for many years with a view to provide a more effective and convenient form of nephroprotection. BNP7787 (disodium 2,2′-dithio-bis ethane sulfonate; dimesna, Tavocept™), is a water-soluble disulfide investigational new drug that is undergoing clinical development for the prevention and mitigation of clinically important chemotherapy-induced toxicities associated with platinum-type chemotherapeutic agents. We hypothesized that part of BNP7787’s mechanism of action (MOA) pertaining to the potential prevention of cisplatin-induced nephrotoxicity involves the inhibition of gamma-glutamyl transpeptidase (GGT) activity, mediated by BNP7787-derived mesna–disulfide heteroconjugates that contain a terminal gamma-glutamate moiety [e.g., mesna–glutathione (MSSGlutathione) and mesna–cysteinyl-glutamate (MSSCE)].MethodsInhibition studies were conducted on human and porcine GGT to determine the effect of mesna–disulfide heteroconjugates on the enzyme’s activity in vitro. These studies utilized a fluorimetric assay that monitored the hydrolysis of l-gamma-glutamyl-7-amino-4-trifluoromethylcoumarin (GG-AFC) to AFC.ResultsMesna–disulfide heteroconjugates that contained gamma-glutamyl moieties were potent inhibitors of human and porcine GGT. An in situ-generated mesna–cisplatin conjugate was not a substrate for GGT.ConclusionsThe GGT xenobiotic metabolism pathway is postulated to be a major toxification pathway for cisplatin nephrotoxicity, and BNP7787 may play a novel and critical therapeutic role in the modulation of GGT activity. We further postulate that there are two general mechanisms for BNP7787-mediated nephroprotection against cisplatin-induced nephrotoxicity involving this pathway. First, the active BNP7787 pharmacophore, mesna, produces an inactive mesna–cisplatin conjugate that is not a substrate for the GGT toxification pathway (GGT xenobiotic metabolism pathway) and, second, BNP7787-derived mesna–disulfide heteroconjugates may serve as selective, potent inhibitors of GGT, possibly resulting in nephroprotection by a novel means.

Context-free spheres: a new method for rapid CPK image generation

Abstract A new algorithm for rendering CPK images of molecules is presented. The algorithm is based on the observation that (given certain assumptions) the appearance of a sphere representing an atom is independent of the atoms position or orientation. For example, the size of a spheres projection on the viewing plane is independent of its distance from the viewing plane. The shading of a sphere is dependent only on lighting parameters that are identical for each atom type. This algorithm takes advantage of this observation by precomputing a template for each unique atom type and stamping these into the image with appropriate offsets in X, Y and Z. The implementation described herein enables generation of CPK images an order of magnitude faster than previous methods, with little sacrifice in image quality.

Applications of ray tracing in molecular graphics

Ray tracing is an elegant and powerful technique for creating computer-generated images. The wide variety of geometric primitives and realistic effects, such as reflections, transparency, and shadows, make it one of the most popular rendering methods in use today. We present a brief introduction to ray tracing and discuss some of the computational issues involved. Examples illustrate ray tracings effectiveness for producing high-quality visualizations of molecular structures.

BNP7787-Mediated Modulation of Paclitaxel- and Cisplatin-Induced Aberrant Microtubule Protein Polymerization In vitro

Taxane and platinum drugs are important agents in the treatment of cancer and have shown activity against a variety of tumors, including ovarian, breast, and lung cancer, either as single agents or in combination with other chemotherapy drugs. However, a serious and prevalent side effect of taxane (docetaxel and all formulations/derivatives of paclitaxel) and platinum (cisplatin, carboplatin, and oxaliplatin) agents is dose-limiting chemotherapy-induced peripheral neuropathy (CIPN). CIPN can result in treatment delays, dose modifications, and, in severe cases, discontinuation of chemotherapy. Consequently, effective treatments for CIPN are needed. Dimesna (BNP7787; Tavocept TM; disodium 2,2′-dithio-bis-ethanesulfonate) is an investigational drug that is undergoing international clinical development as a treatment that is coadministered with first-line taxane and platinum combination chemotherapy in patients with inoperable advanced primary adenocarcinoma of the lung. BNP7787 is currently being developed with the objective of increasing the survival of cancer patients receiving taxane- and/or cisplatin-based chemotherapy. Additional data indicate that BNP7787 may also protect against common and serious chemotherapy-induced toxicities, including chemotherapy-induced anemia, nausea, emesis, nephrotoxicity, and neuropathy, without interfering with antitumor activity of the chemotherapeutic agent(s). Studies herein show that BNP7787 prevents aberrant microtubule protein (MTP) polymerization that is caused by exposure of MTP to paclitaxel or cisplatin. BNP7787 modulates paclitaxel-induced hyperpolymerization of MTP in a dose-dependent manner, and mesna, an in vivo metabolite of BNP7787, protects against time-dependent cisplatin-induced inactivation of MTP. We propose that interactions between BNP7787 and MTP may play a role in BNP7787-mediated protection against CIPN. Mol Cancer Ther; 9(9); 2558–67. ©2010 AACR.

A recombinant reporter system for monitoring reactivation of an endogenously DNA hypermethylated gene

Reversing abnormal gene silencing in cancer cells due to DNA hypermethylation of promoter CpG islands may offer new cancer prevention or therapeutic approaches. Moreover, such approaches may be broadly applicable to enhance the efficacy of radiotherapy, chemotherapy, or immunotherapy. Here, we demonstrate the powerful utility of a novel gene reporter system to permit studies of the dynamics, mechanisms, and translational relevance of candidate therapies of this type in human colon cancer cells. The reporter system is based on in situ modification of the endogenous locus of the tumor-suppressor gene SFRP1, a pivotal regulator of the Wnt pathway that is silenced by DNA hypermethylation in many colon cancers. The modified SFRP1-GFP reporter allele used remained basally silent, like the unaltered allele, and it was activated only by drug treatments that derepress gene silencing by reversing DNA hypermethylation. We used the established DNA methyltransferase inhibitor (DNMTi) 5-aza-deoxycitidine (DAC) to show how this system can be used to address key questions in the clinical development of epigenetic cancer therapies. First, we defined conditions for which clinically relevant dosing could induce sustained induction of RNA and protein. Second, we found that, in vivo, a more prolonged drug exposure than anticipated was essential to derepress gene silencing in significant cell numbers, and this has implications for generating effective anticancer responses in patients with hematopoietic or solid tumors. Finally, we discovered how histone deacetylase inhibitors (HDACi) alone, when administered to cells actively replicating DNA, can robustly reexpress the silenced gene with no change in promoter methylation status. Taken together, our findings offer a new tool and insights for devising optimal clinical experiments to evaluate DNMTi and HDACi, alone or in combination, and with other cancer treatments, as agents for the epigenetic management and prevention of cancer.

Cysteine specific targeting of the functionally distinct peroxiredoxin and glutaredoxin proteins by the investigational disulfide BNP7787

Glutaredoxin (Grx), peroxiredoxin (Prx), and thioredoxin (Trx) are redoxin family proteins that catalyze different types of chemical reactions that impact cell growth and survival through functionally distinct intracellular pathways. Much research is focused on understanding the roles of these redoxin proteins in the development and/or progression of human diseases. Grx and Prx are overexpressed in human cancers, including human lung cancers. BNP7787 is a novel investigational agent that has been evaluated in previous clinical studies, including non-small cell lung cancer (NSCLC) studies. Herein, data from activity assays, mass spectrometry analyses, and X-ray crystallographic studies indicate that BNP7787 forms mixed disulfides with select cysteine residues on Grx and Prx and modulates their function. Studies of interactions between BNP7787 and Trx have been conducted and reported separately. Despite the fact that Trx, Grx, and Prx are functionally distinct proteins that impact oxidative stress, cell proliferation and disease processes through different intracellular pathways, BNP7787 can modify each protein and appears to modulate function through mechanisms that are unique to each target protein. Tumor cells are often genomically heterogeneous containing subpopulations of cancer cells that often express different tumor-promoting proteins or that have multiple dysregulated signaling pathways modulating cell proliferation and drug resistance. A multi-targeted agent that simultaneously modulates activity of proteins important in mediating cell proliferation by functionally distinct intracellular pathways could have many potentially useful therapeutic applications.

Stabilization of the Karenitecin® lactone by alpha-1 acid glycoprotein.

PurposeCamptothecins contain a lactone ring that is necessary for antitumor activity, and hydrolysis of the lactone ring yields an inactive carboxylate species. Human serum albumin (HSA) and alpha-1 acid glycoprotein (AGP) are clinically significant plasma proteins thought to have important roles in camptothecin lactone stability. Herein, we examined the effect(s) of HSA and AGP on the lactone stability of Karenitecin, a novel, highly lipophilic camptothecin analog, currently at the phase 3 clinical testing stage.MethodsAn AGP-immobilized protein column was used to develop HPLC methods to evaluate the effect(s) of physiologically relevant HSA and AGP concentrations on the lactone/carboxylate ratio and hydrolysis kinetics of Karenitecin, camptothecin (CPT), and topotecan (TPT).ResultsPhysiologically relevant concentrations of HSA and AGP substantially slowed Karenitecin lactone hydrolysis. AGP was notably more effective at protecting the Karenitecin lactone from hydrolysis than HSA was in promoting hydrolysis. Additionally, AGP reversed the hydrolysis of partially hydrolyzed Karenitecin lactone. In contrast, HSA and AGP had minimal effects on hydrolysis of the TPT lactone, while the AGP/HSA solutions dramatically accelerated hydrolysis of the CPT lactone.ConclusionAGP strongly enhances the lactone stability of Karenitecin. Since Karenitecin is highly protein-bound in human plasma and exhibits greater lactone stability, relative to other camptothecins, in patient plasma samples, this newly identified role of AGP in promoting lactone stability may have important implications for the design of more effective anticancer agents within the Karentecin™ and camptothecin classes.