Surrogate Markers Of Efficacy Research Articles

Finding What You Are Not Looking for: Strategies for Developing Novel Treatments in Psychiatry

Psychopharmacological treatments in psychiatry are often surprises. Original targets frequently fail, and when successful, may only be the opening volley in a series of ever more important therapeutic applications. Drug development may begin by hypothesis-driven targeting of therapeutic indications with an agent of known and novel mechanism of action. Although this may generate a highly feasible therapeutic indication and can proceed by a well-worn regulatory pathway with known approvable endpoints, it may not only be the least innovative but also the least commercially successful strategy. Because surrogate markers of efficacy are only theoretically attractive but still largely elusive for psychiatric disorders, drug development strategies may need to proceed instead by opportunistic capturing of signals from clinical use of new agents once they enter clinical practice. Outcomes and dosing for clinical trial populations may not match those in clinical practice, so observations from clinical practice must feed back into new clinical trials. In many ways, once efficacy is proven for the originally targeted indication, drug development begins afresh. To get to secondary stages of novel indications for psychiatric drugs and thus to maximize each drug's therapeutic potential, evidence-based prescribing is followed by prescribing-based evidence, namely feedback from clinical practice into clinical proof-of-concept studies followed by large-scale studies and new indications. In many cases, the new indications are the more important therapeutic contributions and the most successful commercial application of a drug. Here we describe this strategy of psychiatric drug development and provide numerous examples.

Therapeutic options in androgen‐independent prostate cancer: building on docetaxel

Of men with metastatic prostate cancer who undergo androgen ablation, 70-80% respond rapidly to therapy, as manifested by a reduction in prostate cancer-related symptoms and declines in serum prostate-specific antigen (PSA) level. Unfortunately, after a median of 18-24 months, nearly all patients with metastatic prostate cancer will progress to androgen independence. Until recently the standard of care for treating hormone-refractory prostate cancer (HRPCa) was the combination of mitoxantrone and prednisone, which palliated bone pain but did not extend survival. Two randomized trials with > 1700 patients showed for the first time a survival benefit for patients with HRPC treated with chemotherapy; when compared with mitoxantrone-based therapy, docetaxel based-therapy reduced the risk of death by 20-24%. Future trials in HRPC are attempting to improve the efficacy of docetaxel by incorporating new agents targeting angiogenesis, apoptosis, and signal transduction pathways; there is promising activity for these novel combinations in phase I and II studies. Concepts are also being refined about definitions of response and progressive disease, patient eligibility criteria, and the validity of surrogate markers of efficacy and survival, as shown by changes in PSA level.

Standardization of Functional Immune Cell-Based Assays: An Integral Aspect to Vaccine and Biologic Development and Validation.

The utility of the ex-vivo evaluation of immune cell functionality in the context of a) Determining an efficacious vaccine strategy for infectious diseases/cancer, b) Determining a tolerance profile in autoimmunity and transplantation, and c) understanding the basic mechanisms of immune cell responses in disease pathogenesis is well recognized.However, the benefit of these assays as surrogate markers of immune cell activity in vivo has not been fully realized due to the variable nature of these in vitro assays which is particularly pronounced in T cell functional assays. This variability arises from a variety of factors ranging from choice of assay, source of the cells, the sample processing methodology (isolation, freezing, thawing, and culturing), sample staining protocol for the chosen assay and ultimately data analysis, and data reduction. With a view to reducing variability and standardizing targeted steps of T cell functional assays, an automated methodology for simultaneous staining and analysis of multiple intracellular cytokines and cytotoxicity markers via flow cytometry was developed and validated. A 5-color flow cytometry assay (2–3 surface markers; 2 intracellular markers) was developed to characterize the restricted polyclonal (SEB/CD28) and antigen specific (CEF peptide pool) cytokine and cytotoxic profile response in human PBMCs. A modification to available sample preparation instruments was performed that enabled the automated pipetting, incubation, and staining of intracellular and surface molecules of stimulated human peripheral blood mononuclear cell populations (PBMC) for flow cytometric analysis.Statistically significant reductions in both inter and intra assay variability was observed in the automated methodology as compared to the manual assay with improvements in CVs for positive cell numbers and mean fluorescence intensity. For example, the inter assay CVs for IFNg cytokine producing CD4+ T cell populations improved from approximately 15 to 5, while the mean fluorescence intensity improved nearly 5 fold with automation. Importantly, the automated methodology furnished comparable responses in percent positive cytokine/cytotoxicity profiles as compared to the manual method while reducing the “handson” sample preparation and analysis time from 2 hours to 20 minutes. With the standardization of functional assays, other sources of variability in assays result can now be addressed specifically e.g. specimen handling, freezing, thawing, culturing, or biological. Standardized multiparametric functional profiling of the cells thus reveals the complex nature of the immune response and lends credence to their use as surrogate markers of efficacy and functionality.

An Integrated Approach to Analyzing Activation Profiles in Immune Cells by Combining Cytomic and Proteomic Techniques of Cell Analysis/Sorting and Protein Fractionation.

Understanding complex responses in biological systems is important to the development of new biomarkers, diagnostic assays, drugs and biologics required for early disease detection, prognosis, monitoring, and treatment. Although several cutting edge technologies have been introduced in the last decade, they have not significantly impacted the speed and economics of new drug applications and introduction of relevant diagnostic tests. In order to overcome this predicament, a Systems Biology approach is necessary to interrogate complex biological responses. This requires that assays that have so far been carried out in isolation, for e.g. gene expression, protein synthesis, phenotype and function, etc. need to be integrated and evaluated in a complementary fashion.In the current study, the authors have attempted such an evaluation by integrating well-known techniques of flow cytometry-based phenotypic analysis and cell sorting with protein fractionation and analysis to evaluate immune cellular activation profiles. To evaluate changes in protein profiles associated with the activation of an immune response, peripheral blood mononuclear cells (PBMCs) were stimulated with the superantigen, Staphylococcus enterotoxin B (SEB) and anti-CD28 or left un-treated for 24 hours. Lysates of PBMC populations from each culture were directly fractionated by two-dimensional gel-free liquid chromatography using isoelectric point (pI) and hydrophobicity. Alternatively, flow-based sorting techniques were 1st utilized to isolate T cells of interest from activated and control cultures and then fractionated as described above. Cell free supernatants from activated and non activated cultures were also fractionated and analyzed.The 1st dimension fractions obtained by separation based on pI alone did not reveal significant differences in activated and non activated lysates. The majority of the proteins in both the sorted and non-sorted lysates eluted in the acidic fractions of the pH gradient. However, using advanced differential display software, the hydrophobicity-dependent second dimension separations of the 1st dimension pI fractions did reveal significant quantitative and qualitative differences for several peaks in both the acidic and basic regions of the gradient in the activated and non activated fractions. Further combination of sorting of T cell populations with two-dimensional gel-free liquid chromatography permitted the characterization of an increased number of proteins that were up or down regulated by activation as compared to non sorted cell cultures. Thus the cumulative approach of sorting and 2-dimensional analysis was the most sensitive in discovering changes associated with activation. Such profiles could potentially be used as surrogate markers of efficacy in vaccine development and immunotoxicity in drug development. Further combinations of genomic, proteomic and cytomic profiling will further advance and ultimately simplify the discovery process and enable the mapping of biological pathways to accomplish a unified evaluation of relevant biomarkers in this response and other clinical models.

764 POSTER A novel mode of antitumor activity for imatinib mesylate: consequences for the design of surrogate markers of efficacy and combination therapies

764 POSTER A novel mode of antitumor activity for imatinib mesylate: consequences for the design of surrogate markers of efficacy and combination therapies

How to Interpret Surrogate Markers of Efficacy in Osteoporosis

How to Interpret Surrogate Markers of Efficacy in Osteoporosis

A novel mode of antitumor activity for imatinib mesylate: Consequences for the design of surrogate markers of efficacy and combination therapies

2516 We have recently reported that STI571 has not only a tumor cell autonomous effect but also acts on host dendritic cells (DC) to promote natural killer (NK) cell activation and NK cell-dependent antitumor effects in mice. Moreover, about 50% of gastrointestinal stromal tumor (GIST) bearing patients undergoing therapy with STI571 acquire NK cell activation correlating with clinical outcome. The study of the Time To Progression (TTP) for 43 patients that benefited from a median follow up of 13.2 months in both cohorts of GIST, those exhibited enhanced NK cell functions (22/43) at 2 months of Gleevec versus those who did not (21/43) revealed that TTP is significantly longer in patients with NK cell activation (Log Rank Test, p=0.03). The potential associated prognostic factors: type of c-kit mutation, extra-gastric primary tumor, haemoglobin level < 7 g/dL, performance status over 2 and pulmonary metastases at entry, were all comparable in these two cohorts. The lack of STI571-mediated NK cell induction found in the other 50% of cases could be assigned to the presence of high numbers of CD4+CD25highregulatory T cells (Treg) in blood at entry, which were shown, by us, to inhibit NK cell effector functions in human ex-vivo and in-vitro. The mean percentages of Treg among CD3+CD4+ T cells in GIST patients displaying NK cell induction were not elevated as compared with normal volunteers (1.1% ± 0.3% vs 1.2% ± 0.4%, respectively, p = 0.5) whereas these yields were increased by three fold in the group of patients with no NK cell induction (3.2% ± 0.8%, p = 0.02). We finally found that the combination of immunopotentiating dosages of cyclophosphamide, aimed at reducing Treg function, with STI571 was synergistic in a mouse (C57BL/6) model of lung melanoma (B16F10 cells) metastases. Altogether, NK cell activation is a novel surrogate marker of efficacy of STI571 which is critical for TTP and could be enhanced by pre-treatment of GIST patients with Treg inhibitors. No significant financial relationships to disclose.

Pharmacokinetics of panipenem/betamipron in patients with end-stage renal disease

Panipenem/betamipron (Carbenin), a parenteral carbapenem antibiotic, is used for the treatment of severe and intractable bacterial infections caused by gram-positive and gram-negative bacteria. Because 30% of panipenem and most of the betamipron are excreted in the urine in an unchanged form, renal function is the important determinant of the dosage regimen of panipenem/betamipron. In this study, the pharmacokinetics of panipenem/betamipron were investigated in patients with end-stage renal disease (ESRD) undergoing hemodialysis treatment to establish an appropriate dose regimen. We further attempted to predict the in vivo clearance in patients undergoing hemodialysis based on the in vitro dializability. The pharmacokinetics of panipenem/betamipron were investigated in eight patients after a 1-h intravenous infusion of panipenem/betamipron (500 mg/500 mg). The in vitro extraction ratios of panipenem/betamipron through a high-flux dialyzer were obtained, and compared with those obtained in vivo. The clearances of panipenem in patients were 9.53 +/- 1.26 l/h with hemodialysis, and 2.92 +/- 0.238 l/h without hemodialysis. In contrast, those of betamipron were 4.18 +/- 0.643 l/h and 0.615 +/- 0.511 l/h, respectively. The clearance of panipenem with hemodialysis were predicted well from in vitro extraction ratios, while that of betamipron was overestimated about 1.4-fold, probably due to high plasma protein binding and the binding difference between patients and healthy subjects. After comparing the pharmacokinetic behavior of panipenem in patients with ESRD and that of a surrogate marker of efficacy, we recommend that these patients be treated with 500 mg/500 mg of panipenem/betamipron once daily, which gives a similar clinical result in a patient with normal renal function.

Overview of the Current Status of Human Epidermal Growth Factor Receptor Inhibitors in Lung Cancer

Although chemotherapy remains the standard of care for lung cancer, new less toxic drugs are urgently needed. Targeted agents represent a new era in cancer therapy, and non-small-cell lung cancer (NSCLC) is at the forefront of many development programs. An exciting target is the human epidermal growth factor receptor (EGFR, ie, HER1), and agents targeting this receptor, including gefitinib, cetuximab, and erlotinib (OSI-774; Tarceva), are being investigated. These agents have antitumor activity and are less toxic than most therapies. Based on phase II data, gefitinib received US approval for third-line treatment of patients with locally advanced or metastatic NSCLC. Cetuximab is licensed in the United States for patients with metastatic colorectal carcinoma. However, erlotinib, recently approved in the United States for second- and third-line treatment of patients with locally advanced or metastatic NSCLC, is the only agent of this class to improve survival as monotherapy in patients with advanced, refractory NSCLC, as shown in a phase III placebo-controlled trial. Phase III trials of erlotinib and gefitinib combined with chemotherapy were disappointing, which could be the result of drug scheduling, chemotherapy combinations, or other factors. Patient characteristics may also affect outcome, and research is ongoing to identify predictive markers of response to enable patient selection and improve outcome. Recently identified mutations within the HER1/EGFR tyrosine kinase (TK) domain may provide insight into why some patients respond rapidly to HER1/EGFR tyrosine kinase inhibitors. Surrogate markers of efficacy are also being investigated, including rash, which could be used to monitor and optimize antitumor activity. Therefore, although more work is required, data indicate that HER1/EGFR inhibitors will play an important role in treating patients with NSCLC.

Posttransplant immunotherapy with a GM-CSF-based tumor vaccine following autologous stem cell transplant (ASCT) for acute myeloid leukemia (AML)

6545 Background: Preclinical models have demonstrated the efficacy of GM-CSF secreting cancer vaccines accompanied by vaccine-primed lymphocyte infusion following ASCT. Methods: Patients ≤ 60 years old with de novo AML (excluding M3) were enrolled. Leukemia cells were harvested at diagnosis followed by induction and consolidation chemotherapy and ASCT. A pretransplant vaccine composed of irradiated autologous leukemia cells mixed with GM-CSF gene-modified K562 cells (K562/GM) was given followed by collection of vaccine-primed lymphocytes that were reinfused with the stem cell graft. Posttransplant vaccinations were initiated at week 6 (or upon platelet engraftment) and given every 3 weeks (10x107 tumor cells + 4x107 K562/GM cells) x 8 vaccinations. Results: Leukemia cell harvest was successful in 44/45 patients (blood draw 17, leukapheresis 24, bone marrow aspirate 4). To date, 34/41 patients (83%) have obtained a complete remission (CR) with induction chemotherapy, 17 have received the pretransplant vaccination, and 8 have initiated posttransplant vaccinations. Vaccines have been well tolerated with evidence of local injection site reactions in 16/17 patients. Delayed-type hypersensitivity (DTH) reactions to irradiated autologous tumor were negative pre-vaccination in 14/16 and converted to positive in 3/5 to date following 4 posttransplant vaccinations. Minimal residual disease (MRD) is being monitored by quantitative analysis of peripheral blood (PB) and bone marrow (BM) for WT1, a leukemia-associated gene, by RT-PCR. All patients had persistently detectable WT1 transcripts in PB and BM at enrollment. Most patients in CR analyzed to date had detectable WT1 transcripts in BM following induction (27/27), consolidation (14/15), and ASCT (4/6). A decrease in WT1 levels in BM was noted in 8/12 following the pretransplant vaccination. Conclusions: Collection of large quantities of autologous leukemia cells for vaccine production is feasible. Analysis of MRD by WT1 RT-PCR, in addition to immune response, may serve as a useful surrogate marker of efficacy in patients vaccinated in remission. Author Disclosure Employment or Leadership Consultant or Advisory Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Cell Gensys Cell Genesys Cell Genesys

Posttransplant immunotherapy with a GM-CSF-based tumor vaccine following autologous stem cell transplant (ASCT) for acute myeloid leukemia (AML)

6545 Background: Preclinical models have demonstrated the efficacy of GM-CSF secreting cancer vaccines accompanied by vaccine-primed lymphocyte infusion following ASCT. Methods: Patients ≤ 60 years old with de novo AML (excluding M3) were enrolled. Leukemia cells were harvested at diagnosis followed by induction and consolidation chemotherapy and ASCT. A pretransplant vaccine composed of irradiated autologous leukemia cells mixed with GM-CSF gene-modified K562 cells (K562/GM) was given followed by collection of vaccine-primed lymphocytes that were reinfused with the stem cell graft. Posttransplant vaccinations were initiated at week 6 (or upon platelet engraftment) and given every 3 weeks (10x107 tumor cells + 4x107 K562/GM cells) x 8 vaccinations. Results: Leukemia cell harvest was successful in 44/45 patients (blood draw 17, leukapheresis 24, bone marrow aspirate 4). To date, 34/41 patients (83%) have obtained a complete remission (CR) with induction chemotherapy, 17 have received the pretransplant vaccination, and 8 have initiated posttransplant vaccinations. Vaccines have been well tolerated with evidence of local injection site reactions in 16/17 patients. Delayed-type hypersensitivity (DTH) reactions to irradiated autologous tumor were negative pre-vaccination in 14/16 and converted to positive in 3/5 to date following 4 posttransplant vaccinations. Minimal residual disease (MRD) is being monitored by quantitative analysis of peripheral blood (PB) and bone marrow (BM) for WT1, a leukemia-associated gene, by RT-PCR. All patients had persistently detectable WT1 transcripts in PB and BM at enrollment. Most patients in CR analyzed to date had detectable WT1 transcripts in BM following induction (27/27), consolidation (14/15), and ASCT (4/6). A decrease in WT1 levels in BM was noted in 8/12 following the pretransplant vaccination. Conclusions: Collection of large quantities of autologous leukemia cells for vaccine production is feasible. Analysis of MRD by WT1 RT-PCR, in addition to immune response, may serve as a useful surrogate marker of efficacy in patients vaccinated in remission. Author Disclosure Employment or Leadership Consultant or Advisory Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Cell Gensys Cell Genesys Cell Genesys

Cancer therapeutics: understanding the mechanism of action.

An intended consequence of the significant investment to characterize the mammalian genome, and its alterations in neoplastic diseases, has been the discovery and commercialization of new approaches to anticancer therapy. As a result, the list of available targets, formerly directed against the processes of DNA replication and mitosis, or in hormonal regulation of growth of tissue, has been dramatically extended. Many of the newer targets represent normal or aberrant signaling pathways, and are present within the cancer cell as second messengers, on its surface (as receptors), or in the external milieu (as ligands). These targets are, therefore, important to the cancer cell phenotype, and affect proliferation, differentiation, and death options for the cell. Another group of targets encompass the cancer cell's relationship to the tissue environment (both stroma and nonneoplastic cells). These targets involve interactions with blood supply (angiogenesis), immune function (evasion), and matrix (invasion and metastasis). Thus, most targets are directly or indirectly critical to some aspect of cancer cell physiology, although a few additional targets are being approached as localization signals for the delivery of otherwise less specific chemotherapeutic or radiotherapeutic agents. The development of new therapeutic approaches has expanded the scope of research required to characterize the mechanism of action for anticancer agents in preclinical models and in clinical trials. In preclinical research, mechanism of action studies have supported the selection of therapeutic agents, appropriate models of efficacy, and experimental design, as well as rational characterization and prediction of nontumor (host) effects. In clinical research, mechanism of action studies have supported the identification of surrogate markers of efficacy (critical for determining adequacy of dose and latency of response), and the selection of patient subpopulations and tumor subtypes most likely to exhibit clinical responses. Finally, information on mechanism of action may suggest strategies for combination therapies and predict potential mechanisms of disease resistance to therapy.

Schedule-dependent molecular effects of the proteasome inhibitor bortezomib and gemcitabine in pancreatic cancer

Background 26S proteasome inhibitors are a novel class of compounds entering clinical trials as a method to increase tumor sensitivity to standard chemotherapy. We determined the effect of alternate sequencing regimens of a proteasome inhibitor and gemcitabine on molecular and cellular responses in pancreatic cancer cells. Materials and methods MIA-PaCa-2 human pancreatic cancer cells were treated with the proteasome inhibitor bortezomib either before, simultaneously or following exposure to gemcitabine. Expression of the cell cycle proteins p21 WAF1/CIP1 and p27 KIP1, and the anti-apoptotic protein BCL-2 were determined by Western blotting. Cell cycle changes and immediate or delayed induction of apoptosis were quantitated. Results Gemcitabine followed by bortezomib induced the greatest induction of apoptosis and long-term inhibition of cell growth. Bortezomib treatment led to accumulation of p21 WAF1/CIP1 and p27 KIP1 and decreased BCL-2; gemcitabine decreased p27 KIP1, induced BCL-2 and had no effect on p21 WAF1/CIP1. When these agents were given in combination or sequence, intermediate changes in these proteins were observed, and the alterations did not correlate with immediate or delayed induction of apoptosis. Conclusions Inhibition of the 26S proteasome following chemotherapy appears to be the most effective regimen, though changes in BCL-2, p21 WAF1/CIP1, p27 KIP1 do not necessarily correlate with the cellular effects when various sequences are examined. Therefore, these proteins may not be the most appropriate surrogate markers of efficacy of this regimen. These data provide the background for the development of the optimal regimen to be used in clinical trials.

Vaccines against dangerous pathogens.

Dangerous pathogens are defined by the UK Health and Safety Executive's advisory committee as category 3 (those which cause severe human disease for which prophylaxis or therapy is usually available) or category 4 (as for category 3, but for which prophylaxis or therapy is not available). Research and development of vaccines for such pathogens is challenging, due to the safety constraints in the manipulation of these pathogens. This chapter discusses the various approaches which can be taken to develop candidate vaccines for these pathogens, including the potential impact of genome sequencing on shortening the time required for R&D. For these pathogens, a direct test of the efficacy of the candidate vaccines in man is not ethical and, therefore, particular emphasis is placed on the demonstration of efficacy in animal models. Emphasis is also placed on the derivation of surrogate markers of efficacy and a demonstration that these correlate with protection in the animal model.

Inhibition of acyl coenzyme A-cholesterol acyltransferase: a possible treatment of atherosclerosis?

Our full understanding of atherosclerosis and our ability to prevent its sequellae are incomplete. As a result, further investigation of novel antiatherosclerotic mechanisms and agents continues. Acyl coenzyme A-cholesterol acyltransferase (ACAT) inhibition has been evaluated as a potential mechanism by which the current treatment arsenal may be expanded. ACAT is present in a variety of tissues and is responsible for catalyzing the conversion of free cholesterol to the more readily stored cholesteryl esters. Impressive lipid effects demonstrated in animals have not generally been demonstrated in human clinical trials. Partial ACAT inhibition with specific agents has resulted in lesion regression and decreased progression, whereas complete ACAT inhibition via genetic alterations has led to an exacerbation of cholesterol deposition in tissues in animal models. No ACAT inhibitor has yet been fully evaluated in human clinical trials for its impact on atherosclerotic disease progression. Several hurdles, such as sample size requirements needed to detect effect over background therapy and lack of sensitive surrogate efficacy markers, have served as a deterrent to the development of this class of investigational drug. However, with recent technologic advancements, more sensitive methods of measuring disease progression may be available. Human clinical trials are currently underway, with several agents reported in Phase II clinical trials. Within the next few years, results from these trials may determine whether or not ACAT inhibitors will be added to the list of treatment options for the prevention of atherosclerotic disease progression.

Plague vaccine research and development.

1. SUMMARY A fully recombinant subunit vaccine is described which provides enhanced protection against bubonic plague and a new prophylactic against the pneumonic form of the disease. The vaccine comprises two subunit antigens termed Fl and V which are individually immunogenic and protective and have additive protective effect in combination. The vaccine has been demonstrated efficacious in small animal models, including a strain of mice with a targeted gene deletion for interleukin 4 (IL4T mice). The mechanism of protection conferred by the vaccine is principally antibody-mediated and antibody titre to Fl + V in the mouse correlates with protection. Surrogate markers of efficacy in man have been identified and will be applied to support clinical trialling of the vaccine. This vaccine could be used to counter bubonic and pneumonic plague in areas of the world where the disease is endemic.

Chemoprevention of DMBA-induced Mammary Carcinogenesis: Relationship Between Induction of Phase II Enzymes, Effects on DMBA-induced Hemoglobin Adducts and Decreases in Mammary Tumor Multiplicity

The chemopreventive potential of 1,2-dithiole-3-thione, ethoxyquin, butylated hydroxanisole (BHA) and β-naphthoflavone (BNF) was investigated in the 7,12-dimethylbenz(a)anthracene (DMBA) rat mammary tumor model. Female Sprague-Dawley rats received a single dose of DMBA (15 mg) at 50 days of age. Chemopreventive agents were administered via the diet, beginning one week prior to DMBA dosing and continuing until one week following DMBA. Tumor latency, multiplicity and incidence were not affected by BHA (2.5 or 5.0 g/kg diet), but administration of low or high doses of β-napthflavone (1.65 and 3.3 g/kg diet), or high doses of ethoxyquin (5.0 g/kg diet) or 1,2-dithiole-3-thione (0.6 g/kg diet), effectively inhibited all parameters of tumorigenesis. It is presumed that many of these agents which decrease the tumorigenicity act by altering the metabolism of the carcinogen resulting in diminished numbers of reactive ultimate carcinogens. We examined both for the induction of enzymes that might alter carcinogen metabolism as well as alterations in levels of DMBA adducts to hemoglobin. A strong correlation was observed between the effect of these agents on carcinogenesis and the induction of phase I1 enzymes (quinone reductase and glutathione S-transferase) and glutathione in the mammary gland. We also examined the effects of BNF, 1.2- dithiol-3-thione and BHA on formation of hemoglobin adducts by DMBA. Similarly to the results on carcinogenesis the relative efficacy of compounds in inhibiting DMBA adduct formation and DMBA induced mammary tumorigenesis was BNF > 1,2 Dithiolthione >> BHA. These results support the hypothesis that these agents work by altering metabolism of DMBA to reactive intermediates but further offer the possibility that modulation of hemoglobin adducts may serve as a surrogate marker of efficacy.

Optimal dosage of insulin and glucose in glucose-insulin-potassium treatment of acute myocardial infarction remains to Be established

Optimal dosage of insulin and glucose in glucose-insulin-potassium treatment of acute myocardial infarction remains to be established.

Markers of HIV infection in the Concorde trial. Concorde Co-ordinating Committee.

The Concorde trial compared immediate (Imm) with deferred (Def) AZT monotherapy in asymptomatic HIV-positive participants. Haematological and immunological markers and weight were measured throughout, and correlated with clinical endpoints. Markers associated with disease progression (CD4 lymphocyte count and percentage, platelets, p24 antigen and beta 2 microglobulin favoured Imm: those associated with toxicity (haemoglobin, neutrophils and white cell count) favoured Def. CD8 and total lymphocyte count did not differ significantly between groups. In multivariate analysis, the combination of baseline CD4, p24 antigen and beta 2m was the best baseline predictor of disease. Including change in CD4 and beta 2m at 12 weeks, or changes over follow-up in these markers significantly improved the fit. Markers were also incorporated into the definition of 'clinical' endpoints. Hazard ratio estimates from end-points that included CD4 < 50 and CD4 < 25 were closest to those for AIDS or death alone, but added very few extra events. Use of other landmark CD4 counts (100 or greater) or relative decreases in counts (25% or more) increased the number of events, but overestimated the effect of immediate AZT. Although AZT had a beneficial effect on the surrogate markers of efficacy evaluated, these changes did not predict clinical outcome, nor could the markers be usefully incorporated into an endpoint definition.

P43 Evaluation of bone marrow micrometastases as potential surrogate marker for efficacy of adjuvant treatment

P43 Evaluation of bone marrow micrometastases as potential surrogate marker for efficacy of adjuvant treatment