Evaluation Of Therapeutic Agents Research Articles

Abstract 6030: Reconstructed Pancreas: A tumor-specific 3D culture platform for accurate evaluation of therapeutic agents in pancreatic cancer

Abstract As it is rarely diagnosed early, the prognosis for patients with pancreatic cancer is grim. The average 5-year survival rate is 10% and only 3% for patients with metastatic disease. Partially because of the late diagnosis and partially because of its biology, treatment options for patients with pancreatic cancer are limited and new interventions are desperately needed to gain the upper hand on this disease. One of the challenges faced by the drug developers looking for agents against pancreatic cancer is capturing the elements of the tumor microenvironment, which provides both a physical barrier and stroma-driven resistance to therapeutic agents. We developed a tumor-specific Reconstructed Pancreas (r-Pancreas) model, which recapitulates the cellular and extracellular elements of the pancreatic tumor microenvironment. In the r-Pancreas model, tumor and stromal cells are embedded in a dense extracellular matrix (ECM) characteristic of pancreatic tumors. Pancreatic tumor cell lines, MiaPaca-2, Panc-1, and Bx-PC3 robustly proliferate and survive for 14 days providing an extended therapeutic window to test anti-tumor compounds in the context of pancreas-specific ECM. Mimicking clinical response pancreatic tumor cells grown in r-Pancreas are sensitive to gemcitabine (IC50=0.4-0.6µM) but are resistant to 5-fluorouracil (IC50=not reached). These cell lines were also 5-10 times less sensitive to gemcitabine when cultured in Matrigel (IC50=3-6µM), soft ECM rich in collagen IV/laminin neither of which is abundant in the pancreas. Incorporating a collagen-rich capsule into the r-Pancreas model further expands its physiological relevance as human pancreatic tumors have been shown to have an outer layer of stiff ECM, which provides a physical barrier that impedes drug access to the tumor. Finally, establishing a co-culture of pancreatic tumor cell lines with primary pancreatic stromal cells creates a complete model enabling testing of novel therapeutic agents within the pancreatic tumor microenvironment. Taken together these data suggest that to be clinically useful in vitro tumor models not only need to allow for 3-dimensional cell growth but also have to incorporate tumor-specific elements of the microenvironment. Citation Format: Eleanore J. Kirshner, Aayushi Ahlawat, Matthew Ryou. Reconstructed Pancreas: A tumor-specific 3D culture platform for accurate evaluation of therapeutic agents in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6030.

Harnessing the Power of Induced Pluripotent Stem Cells and Gene Editing Technology: Therapeutic Implications in Hematological Malignancies.

In vitro modeling of hematological malignancies not only provides insights into the influence of genetic aberrations on cellular and molecular mechanisms involved in disease progression but also aids development and evaluation of therapeutic agents. Owing to their self-renewal and differentiation capacity, induced pluripotent stem cells (iPSCs) have emerged as a potential source of short in supply disease-specific human cells of the hematopoietic lineage. Patient-derived iPSCs can recapitulate the disease severity and spectrum of prognosis dictated by the genetic variation among patients and can be used for drug screening and studying clonal evolution. However, this approach lacks the ability to model the early phases of the disease leading to cancer. The advent of genetic editing technology has promoted the generation of precise isogenic iPSC disease models to address questions regarding the underlying genetic mechanism of disease initiation and progression. In this review, we discuss the use of iPSC disease modeling in hematological diseases, where there is lack of patient sample availability and/or difficulty of engraftment to generate animal models. Furthermore, we describe the power of combining iPSC and precise gene editing to elucidate the underlying mechanism of initiation and progression of various hematological malignancies. Finally, we discuss the power of iPSC disease modeling in developing and testing novel therapies in a high throughput setting.

Evaluation of Therapeutic Agents Targeting the Pathogenesis of Coronary Artery Spasm: A Mini Review.

Coronary artery spasm (CAS) plays an important role in the pathogenesis of ischemic heart disease. The clinical manifestations of CAS include variant angina, myocardial infarction and sudden death. Although endothelial dysfunction and hyperreactivity of vascular smooth muscle cells have been associated with CAS, the underlying mechanisms remain unclear. Thus, there is a long way to go to truly understand the pathogenesis of CAS to formulate effective treatments. This article discusses the pathophysiological mechanisms as well as downstream molecular pathways of CAS, with a focus on potential therapeutic targets.

Abstract P2-12-06: The clinical benefit index: A pilot study integrating treatment efficacy and quality of life in oncology clinical trials

Abstract Background: Breast cancer remains the most frequently diagnosed cancer among women worldwide, accounting for a quarter of all diagnoses. Despite advances in treatment and symptom management, the majority of women will experience some form of drug-related toxicity, psychosocial distress, and subsequent impairments in their quality of life (QoL). Distress and impairments in QoL can interfere with treatment adherence, while engagement in health promoting behaviors and effective management of symptoms has been associated with improved QoL, adherence and increased survival. The utilization of QoL or other Patient Reported Outcome (PRO) measures in clinical trials remains inconsistent, and no uniformly accepted measure exists to integrate QoL data into the assessment of therapeutic agents. There are two goals of the I-SPY 2 QoL Pilot Study: 1) To demonstrate the reporting of an integrated utility-based QOL score, the PROPr, within a novel longitudinal approach that provides a single numerical index of QoL; 2) Generate a Clinical Benefit Index (CBI), a single composite score that integrates the longitudinal PROPr score with a clinical efficacy score, RCB index, to provide a measure that could go beyond clinical efficacy in the evaluation of therapeutic agents in the I-SPY 2 TRIAL. Methods: Study participants were part of the I-SPY 2 TRIAL assessing novel neoadjuvant therapies added to standard chemotherapy in the treatment of Stage 2/3 breast cancer. Participants completed a validated QoL measure at three time points: baseline, prior to surgery, and 1-month post-surgery. QoL was assessed using the NIH PROMIS measure (physical function (four items), anxiety (eight items), depression (eight items), fatigue (eight items), applied cognition (eight items) and social roles (four items)) and results at each time point used to calculate the PROPr, a single utility-based index score to assess overall quality of life. PROPr index utility scores were used to generate a single longitudinal QoL score based on area under the curve modeling. Clinical efficacy was assessed based on the residual cancer burden (RCB) observed at the time of surgery. The CBI was generated by plotting RCB index against the longitudinal PROPr index for each participant and study arm. Results: Only a fraction (n=107) of all patients had complete data across study timepoints and were included in our analyses, and thus our data represent a proof of concept. Patients on the control arm were treated with Paclitaxel followed by anthracycline (AC). Patients in the pilot were assigned either the control arm or six experimental drug arms. The longitudinal PROPr utility index demonstrated a range of outcomes, with some arms more challenging to tolerate, and others much better, ranging from 0.67 to 1.16. The RCB index of the seven study arms ranged from 0.49 to 1.99. The CBI, an integration of the longitudinal PROPr and RCB indexes, also demonstrated a range from 0.43 to 1.60. Conclusion: We are reporting the development of a novel, valid and standardized QoL assessment that should be a routine part of clinical trials in oncology. This proof of concept study suggests that that calculation of the CBI is feasible and can reveal differences in the clinical profiles of therapeutic agents, both in terms of QoL and overall integration of clinical efficacy and QoL. The CBI represents a novel approach to providing summary data that can be easily interpreted as part of clinical trial outcome data. Ideally, these integrated assessments would provide a more comprehensive evaluation of investigational therapies, and ultimately help inform treatment decision discussions between patients and providers. Moving forward, electronic PRO data will be collected as part of routine care in the I-SPY 2 TRIAL, thus enabling the longitudinal PROPr and CBI scores to be generated for every agent evaluated. Citation Format: Amrita Basu, Errol J. Philip, Barry Dewitt, Janel Hanmer, Aheli Chattopadhyay, Christina Yau, Smita Asare, Karyn Digiorgio, Ruby Singhrao, Adam Asare, Jane Perlmutter, I-SPY 2 Consortium, Michelle Melisko, Laura Esserman. The clinical benefit index: A pilot study integrating treatment efficacy and quality of life in oncology clinical trials [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-12-06.

The Northwestern Abdominoplasty Scar Model: A Novel Human Model for Scar Research and Therapeutics.

Summary:There is a growing interest in the development and evaluation of therapeutic agents that improve the cosmetic appearance of scars. Existing nonhuman animal models to study scarring, while valuable, have well-acknowledged limitations, as it is accepted that the biology of human scarring differs significantly from scarring in other species. Moreover, human clinical trials of scarring require large numbers of subjects to achieve statistical power and are plagued by inherent intersubject variability because of the complex nature of wound healing in human beings. As a better alternative, we have developed the Northwestern Abdominoplasty Scar Model—a novel human clinical model that permits analysis of up to 20 cutaneous scars in a single subject and allows for not only visual scar comparison, but also histologic and molecular analyses of factors involved in scarring and wound healing. We have utilized this model in 5 early phase clinical trials designed to test the safety and efficacy of a variety of scar therapeutics without any complications to date. The model not only is applicable to scar therapeutics, but also can be utilized for other applications, such as the testing of implantable biomaterials, injectable products, therapies such as lasers, or even for in vivo study of wound healing processes in humans.

Abstract 4279: Human HER2-overexpressing mouse breast cancer cell lines derived from MMTV.f.HuHER2 mice: characterization and use in a model of metastatic breast cancer

Abstract Preclinical evaluation of therapeutic agents against metastatic breast cancer require cell lines and animal models that recapitulate clinical metastatic breast cancer as much as possible. We have previously used cell lines derived from the neu-N transgenic model to investigate anti-neu targeting of metastatic breast cancer using an alpha-emitter labeled antibody reactive with the rat variant of HER2/neu expressed by the neu-N model. To investigate alpha-emitter targeting of metastatic breast cancer using clinically relevant, commercially available anti-HER2/neu antibodies, we have developed cell lines derived from HuHER2 mice (MMTV.f.HuHER2 obtained from Genetech). HuHER2 mice develop breast cancer spontaneously and with a higher frequency than normal mice. We extracted primary mammary gland tumors, purified the epithelial breast cancer cells, and established 7 different HuHER2 cell lines. We also established 2 different cell lines from spontaneous lung metastases (HuHER2-L1 and -L2). We evaluated HuHER2 protein expression in the cell lines by western blot analysis. Cell surface receptor expression was evaluated by immunofluorescence (IF) staining. We performed qRT-PCR to assess phenotypic measures of aggressiveness and metastatic propensity. The following were evaluated: ER, PR, Twist1, Vimentin and E-Cadherin. Sensitivity to trastuzumab antibody, in vitro, was also assessed by evaluating changes in cellular metabolism via the MTT assay. HuHER2 protein was overexpressed in all of the isolated cell lines. One of the cell lines (denoted HuHER2-6) had approximately 1.5-8 times more protein expression compared to the other 6 cell lines developed. The two cell lines derived from spontaneous lung metastases showed approximately 1.5-fold greater HER2 protein expression than HuHER2-6. HuHER2-6 cell surface HER2 receptor staining by IF was similar to that of BT-474, a high HuHER2 expressing cell line. The 2 lung cell lines also showed comparable cell-surface staining. ER mRNA levels assessed by qRT-PCR were 20% and 0.05% of the level measured in normal mammary gland for the HuHER2-6 and HuHer2-L2 lines, respectively. The PR levels were also substantially lower (<0.01%) relative to normal mammary gland (MG) tissue. The HuHER2-6 line expressed 1.4 times more HuHER2/neu mRNA than BT-474. The mRNA for E-Cadherin in HuHER2-L1 and -L2 was 20% of MG tissue. The mRNA for TWIST1 and Vimentin were similarly elevated 3-fold and 1.5-fold, respectively, relative to MG. At trastuzumab concentrations ranging from 10 to 500 ug/ml, cell metabolism was decreased to 50%. These lines show all the hallmarks of highly aggressive, metastatic breast cancer and are being used to establish a left cardiac ventricle injection model of widespread HER2/neu positive metastatic breast cancer to evaluate combination therapy with alpha-particle emitter labeled HER2/neu reactive antibodies. Citation Format: Sunju Park, George Sgouros. Human HER2-overexpressing mouse breast cancer cell lines derived from MMTV.f.HuHER2 mice: characterization and use in a model of metastatic breast cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4279.

Live Imaging of Host-Parasite Interactions in a Zebrafish Infection Model Reveals Cryptococcal Determinants of Virulence and Central Nervous System Invasion.

ABSTRACTThe human fungal pathogen Cryptococcus neoformans is capable of infecting a broad range of hosts, from invertebrates like amoebas and nematodes to standard vertebrate models such as mice and rabbits. Here we have taken advantage of a zebrafish model to investigate host-pathogen interactions of Cryptococcus with the zebrafish innate immune system, which shares a highly conserved framework with that of mammals. Through live-imaging observations and genetic knockdown, we establish that macrophages are the primary immune cells responsible for responding to and containing acute cryptococcal infections. By interrogating survival and cryptococcal burden following infection with a panel of Cryptococcus mutants, we find that virulence factors initially identified as important in causing disease in mice are also necessary for pathogenesis in zebrafish larvae. Live imaging of the cranial blood vessels of infected larvae reveals that C. neoformans is able to penetrate the zebrafish brain following intravenous infection. By studying a C. neoformans FNX1 gene mutant, we find that blood-brain barrier invasion is dependent on a known cryptococcal invasion-promoting pathway previously identified in a murine model of central nervous system invasion. The zebrafish-C. neoformans platform provides a visually and genetically accessible vertebrate model system for cryptococcal pathogenesis with many of the advantages of small invertebrates. This model is well suited for higher-throughput screening of mutants, mechanistic dissection of cryptococcal pathogenesis in live animals, and use in the evaluation of therapeutic agents.

A nonhuman primate scrub typhus model: protective immune responses induced by pKarp47 DNA vaccination in cynomolgus macaques.

We developed an intradermal (ID) challenge cynomolgus macaque (Macaca fascicularis) model of scrub typhus, the leading cause of treatable undifferentiated febrile illness in tropical Asia, caused by the obligate intracellular bacterium, Orientia tsutsugamushi. A well-characterized animal model is required for the development of clinically relevant diagnostic assays and evaluation of therapeutic agents and candidate vaccines. We investigated scrub typhus disease pathophysiology and evaluated two O. tsutsugamushi 47-kDa, Ag-based candidate vaccines, a DNA plasmid vaccine (pKarp47), and a virus-vectored vaccine (Kp47/47-Venezuelan equine encephalitis virus replicon particle) for safety, immunogenicity, and efficacy against homologous ID challenge with O. tsutsugamushi Karp. Control cynomolgus macaques developed fever, classic eschars, lymphadenopathy, bacteremia, altered liver function, increased WBC counts, pathogen-specific Ab (IgM and IgG), and cell-mediated immune responses. Vaccinated macaques receiving the DNA plasmid pKarp47 vaccine had significantly increased O. tsutsugamushi–specific, IFN-γ–producing PBMCs (p = 0.04), reduced eschar frequency and bacteremia duration (p ≤ 0.01), delayed bacteremia onset (p < 0.05), reduced circulating bacterial biomass (p = 0.01), and greater reduction of liver transaminase levels (p < 0.03) than controls. This study demonstrates a vaccine-induced immune response capable of conferring sterile immunity against high-dose homologous ID challenge of O. tsutsugamushi in a nonhuman primate model, and it provides insight into cell-mediated immune control of O. tsutsugamushi and dissemination dynamics, highlights the importance of bacteremia indices for evaluation of both natural and vaccine-induced immune responses, and importantly, to our knowledge, has determined the first phenotypic correlates of immune protection in scrub typhus. We conclude that this model is suitable for detailed investigations into vaccine-induced immune responses and correlates of immunity for scrub typhus.

Accounting for perception, placebo and unmasking effects in estimating treatment effects in randomised clinical trials

There is a rich literature on the role of placebos in experimental design and evaluation of therapeutic agents or interventions. The importance of masking participants, investigators and evaluators to treatment assignment (treatment or placebo) has long been stressed as a key feature of a successful trial design. Nevertheless, there is considerable variability in the technical definition of the placebo effect and the impact of treatment assignments being unmasked. We suggest a formal concept of a 'perception effect' and define unmasking and placebo effects in the context of randomised trials. We employ modern tools from causal inference to derive semi-parametric estimators of such effects. The methods are illustrated on a motivating example from a recent pain trial where the occurrence of treatment-related side effects acts as a proxy for unmasking.

Value in Development of a TAPIR-Like Mouse Monoclonal Antibody to Aβ

Value in Development of a TAPIR-Like Mouse Monoclonal Antibody to Aβ

Off-Label-Use: Update und Bezug zur Urologie

The use of pharmaceuticals beyond the approved indication and conditions (off-label use) is of increasing public interest in times of necessary financial constraints in public health together with the high requirements for drug safety to protect the patient. Remarkably, more than half of the therapies in oncology are performed as off-label use. The discussion on off-label use is controversial and based on different points of interests. Evaluation of therapeutic agents by the pharmaceutical industry is predominantly driven by marketing and business requirements. As a consequence, treatment of rare diseases is often only possible by off-label use, creating more or less an off-label need. Reimbursement by health-care insurance is based on the approval of a pharmaceutical substance for a particular situation, because only the rigorous licensing process assures that the verified efficacy is higher than the, often severe, adverse side effects. It is a well known fact that the sometimes adverse events, which occur on administration of substances in an off-label fashion, are not included in the information on the regular use of a given drug. Finally, physicians request a controlled off-label use, which only allows experienced colleagues and (sub)-specialized oncologists to use pharmaceuticals in an off-label fashion. Up to date no legal documents exist that provide regulations for such an off-label usage.

Gait analysis in a murine model of collagen-induced arthritis

Murine collagen-induced arthritis (CIA) has become a valuable animal model for elucidating pathogenic mechanisms and evaluating therapeutic effects for rheumatoid arthritis. Recent advances in digital imaging and computer technology have enabled gait analysis to develop into a powerful tool for objectively detecting functional deficits in human and animal models. The present study explored the use of non-invasive video-capture gait analysis in the evaluation of a murine CIA model. CIA was induced in 45 female DBA/1LacJ mice (8 to 10 weeks old) by immunization with lyophilized bovine articular type II collagen. Gait parameters were determined by ventral plane videography and were correlated to traditional arthritis clinical scores. Our results showed that increases in clinical scores that measure the severity of CIA corresponded to changes in multiple gait parameters that reflect both morphologic (increases in paw area) and functional (increase in stride frequency, decrease in stride length, hind-limb paw placement angle, as well as stride, stance, and braking times) deficits. Our work indicated that the non-invasive video-capture device may be used as a simple and objective data acquisition system for quantifying gait disturbances in CIA mice for the investigation of mechanisms and the evaluation of therapeutic agents.

Cell Lines as In Vitro Models for Drug Screening and Toxicity Studies

ABSTRACTCell culture is highly desirable, as it provides systems for ready, direct access and evaluation of tissues. The use of tissue culture is a valuable tool to study problems of clinical relevance, especially those related to diseases, screening, and studies of cell toxicity mechanisms. Ready access to the cells provides the possibility for easy studies of cellular mechanisms that may suggest new potential drug targets and, in the case of pathological-derived tissue, it has an interesting application in the evaluation of therapeutic agents that potentially may treat the dysfunction. However, special considerations must be addressed to establish stable in vitro function. In primary culture, these factors are primarily linked to greater demands of tissue to adequately survive and develop differentiated conditions in vitro. Additional requirements include the use of special substrates (collagen, laminin, extracellular matrix preparations, etc.), growth factors and soluble media supplements, some of which can be quite complex in their composition. These demands, along with difficulties in obtaining adequate tissue amounts, have prompted interest in developing immortalized cell lines which can provide unlimited tissue amounts. However, cell lines tend to exhibit problems in stability and/or viability, though they serve as a feasible alternative, especially regarding new potential applications in cell transplant therapy. In this regard, stem cells may also be a source for the generation of various cell types in vitro. This review will address aspects of cell culture system application, with focus on immortalized cell lines, in studying cell function and dysfunction with the primary aim being to identify cell targets for drug screening.

Pathogenicity of Cryptosporidium parvum--evaluation of an animal infection model.

With the intention of developing a standardised method for assessment of pathogenicity of Cryptosporidium parvum, the CPB-0 isolate was studied by propagation in 1-day-old calves followed by inoculation into specific pathogen free (SPF) piglets. The experiment was repeated. Diarrhoea and shedding of oocysts were seen in all animals infected with the CPB-0 isolate. Clinical signs included depression, inappetence, vomiting (exclusively in the piglets), and death. Histological examination at 17 and 19 days post-infection revealed parasitic stages and microscopic changes primarily restricted to colon and rectum.The unintended presence of rotavirus in some of the experimental animals revealed an additive or synergistic effect between rotavirus and C. parvum as indicated by prolonged diarrhoea, increased oocyst shedding, decreased weight gain and elevated levels of serum haptoglobin and serum amyloid A (SAA) in piglets infected simultaneously with both pathogens. The difference in daily weight gain between infected and control animals was significant only for piglets co-infected with rotavirus. The acute phase response of haptoglobin and SAA was characterised by a large individual variation. In piglets, co-infected with rotavirus, the levels of serum haptoglobin were 3.5 and 4.6 times higher in the infected versus the controls 6 and 9 dpi, respectively (mean values: 2411 μg/ml±S.D. 2023 and 1840 μg/ml±S.D. 1697). In the controls infected with rotavirus, peak haptoglobin concentration was seen 3 dpi (mean: 1022 μg/ml±S.D. 425). Elevated levels of SAA were seen in 1 of 6 piglets infected with C. parvum, and in 5 of 6 piglets co-infected with rotavirus. Tumour necrosis factor alpha (TNFα) was undetectable in all serum samples from piglets.The obvious advantages of the SPF pig model are the naturally acquired intestinal microflora, the development of distinct clinical signs similar to cryptosporidiosis in humans and calves, the size of the animals, and the accessibility of individuals born within a short time span. This makes the model ideal for dose–response studies, evaluation of therapeutic agents as well as for assessment of differences in the clinical response to isolates of diverse genetic background. In conclusion, it was shown that the CPB-0 isolate was pathogenic to calves and piglets at a dose of 2.5×105 oocysts, and that the clinical signs could be replicated during separate experiments. Moreover, diarrhoea, oocyst shedding, body weight changes, histological alterations, and the acute phase response of haptoglobin and SAA were identified as useful parameters for discrimination of isolate-specific differences of pathogenicity.

Biomarkers, surrogates, and evaluation of therapeutic agents: a proposed solution.

Biomarkers, surrogates, and evaluation of therapeutic agents: a proposed solution.

Use of disease models in the development and evaluation of therapeutic agents.

A key part of the regulatory review of new therapeutic agents depends on a clear demonstration of their efficacy. There can be difficulties when the evaluations of efficacy depend only on in vitro studies, such as minimum inhibitory concentrations (MICs), and clinical field trials. The MIC data often correlate poorly with in vivo results, and field trials can suffer from the unpredictability of disease outbreaks and from differences in the severity of outbreaks at different sites. This paper discusses the use of experimentally induced diseases as a means of bridging the gap between the in vitro data and the results of field trials.

A Matrix Method for the Evaluation of Therapeutic Agents: A Framework Based on Disease Process-Oriented Mechanisms of Drug Action and Their Effectiveness

A matrix method has been developed for the evaluation of therapeutic agents based on six categories of therapeutic specificities and three levels of therapeutic effectiveness. The therapeutic specificity categories are based on the relationship between a drug’s therapeutic effect and the pathophysiologic process being treated or prevented. The therapeutic effectiveness levels are based on the drug’s degree of effectiveness with respect to the underlying disease or disease process. By providing a framework for comparisons across different therapeutic agents, this matrix evaluation method may have applications in assessing different therapeutic options, choosing clinical trials endpoints, and selecting drug discovery targets.

Investigation on the interaction of commercial forms of streptokinase and human plasminogen: a potential screening procedure for fibrinolytic inhibitors.

Streptokinase activation of human plasminogen is known to produce several enzymatic entities. Initially, the identification and characterization of these various entities were based on molecular model studies which necessitated highly purified biological materials and sophisticated techniques. However, these conditions cannot always be adhered to when alacrity, precision, and cost are often the prime factors governing the choice of a method for the evaluation of therapeutic agents. Our concern was therefore to find a suitable method of investigating inhibitors of the fibrinolytic system without compromising on accuracy, reliability, and reproducibility. We found that the activation of human plasminogen by streptokinase was dependent both on the duration of the activation step and the concentration of streptokinase used. By combining these two factors, activation could be visualized as a dual phase phenomenon. Each phase revealed distinct kinetic parameters and reactivity toward inhibitors such that their identity with the known enzymatic entities could be established. Inhibitors were further assessed with respect to their kinetic profile and were found to conform to known data. Therefore, the proposed method not only allows for direct visualization of the activation process but also meets the requirements for the routine screening of potential therapeutic inhibitors of the fibrinolytic system.

Observations on the Medical Treatment of Inflammatory Bowel Disease

IN THE absence of decisive knowledge of the causes of inflammatory bowel disease (IBD), there continues to be no consistently curative medical treatment for ulcerative colitis and Crohn's disease.^1-3Treatment has included such widely diverse approaches as prefrontal lobotomy,⁴hog extract,⁵Calmette-Guérin bacillus,^6,7vaccines including Bargen's<i>Streptococcus</i>, irradiation,⁸gonadotropins, "regulation of abnormal electrical rhythm of the bowel" with coherin,⁹fasting, tranquilizers, phenylbutazone,¹⁰lithium carbonate,¹¹psychotherapy,¹²mineral water,¹³immunosuppressive drugs, and empirical measures for which rationale is not apparent. Many patients with mild ulcerative colitis and with mild regional enteritis respond favorably to simple treatments, including adequate rest, dietary adjustments, sedation, and perhaps sulfasalazine and other antibacterial agents. The emphasis in this article, therefore, is on selected aspects of the medical treatment of the moderately or severely ill IBD patient. A major flaw in the evaluation of therapeutic agents in IBD is

The Evaluation of Therapeutic Agents and Cosmetics

This book is based on a conference held in August, 1962, just prior to the passage of the drug amendments of 1962 and the subsequent issuance of regulations relative to investigational drugs. As a result of the late appearance of this publication and the failure to revise the papers to reflect the current situation, seven (of the 26) chapters are to a large degree outdated. Unfortunately, these are the chapters addressed to the conference theme, "Evaluation." The other chapters, principally in basic scientific areas, are uneven in content and presentation but have survived the passage of time with smaller loss in value. Even this material could have been improved by more careful editing, as for example, the legends on many graphs. The principal value of this book is to serve as a record of the conference; participants and possibly others may find it an interesting historical record of drug-evaluation procedures