The Metallodrug BOLD-100 Is a Potent Inhibitor of SARS-CoV-2 Replication and Has Broad-Acting Antiviral Activity

The COVID-19 pandemic has highlighted an urgent need to discover and test new drugs to treat patients. Metal-based drugs are known to interact with DNA and/or a variety of proteins such as enzymes and transcription factors, some of which have been shown to exhibit anticancer and antimicrobial effects. BOLD-100 (sodium trans-[tetrachlorobis(1H-indazole)ruthenate(III)]dihydrate) is a novel ruthenium-based drug currently being evaluated in a Phase 1b/2a clinical trial for the treatment of advanced gastrointestinal cancer. Given that metal-based drugs are known to exhibit antimicrobial activities, we asked if BOLD-100 exhibits antiviral activity towards SARS-CoV-2. We demonstrated that BOLD-100 potently inhibits SARS-CoV-2 replication and cytopathic effects in vitro. An RNA sequencing analysis showed that BOLD-100 inhibits virus-induced transcriptional changes in infected cells. In addition, we showed that the antiviral activity of BOLD-100 is not specific for SARS-CoV-2, but also inhibits the replication of the evolutionarily divergent viruses Human Immunodeficiency Virus type 1 and Human Adenovirus type 5. This study identifies BOLD-100 as a potentially novel broad-acting antiviral drug.

Abstract 2259: Novel metallotherapeutic BOLD-100 induces circulating cytokine changes when administered in combination with FOLFOX in advanced gastrointestinal cancer patients

Proven metallotherapeutics, such as cisplatin and oxaliplatin, alter immune responses as part of their multimodal mechanisms-of-action. These immune responses can drive efficacy in specific patient populations and/or in combination with other oncology drugs. BOLD-100, currently in a multinational Phase 2 trial, is a first-in-class metallotherapeutic that (1) alters the unfolded protein response (UPR) through selective GRP78 inhibition, and (2) induces reactive oxygen species (ROS), leading to DNA damage and cell cycle arrest. Collectively, these pathways result in cell death in both sensitive and resistant cancers, giving BOLD-100 the potential to significantly improve outcomes in a wide range of both solid and liquid tumors in combination with other anticancer therapies. BOLD-100 can also alter immune responses, including through induction of immunogenic cell death, but these responses have not been investigated in a clinical population. A recently completed Phase 1b trial investigating BOLD-100 in combination with FOLFOX demonstrated a 3X improvement in progression-free survival (PFS) in 3rd line or later metastatic colorectal cancer patients compared to existing therapies, with a favorable safety profile. In this Phase 1b study, BOLD-100 was administered via IV infusion for 60-90 minutes immediately prior to FOLFOX on a 2-week cycle. To investigate the pharmacodynamics of immune markers, plasma samples were collected at baseline and 1, 6, 24, and 48 hours after initiation of BOLD-100 plus FOLFOX treatment for each of the first 4 cycles, and then at baseline for all subsequent cycles. In 326 samples collected from 15 patients, 48 cytokines were measured via multiplex. Multiple cytokines showed short-term (1 to 48 hours) transient increases in plasma concentration levels, including IL-10, IL-27, G-CSF, MIP-1β, IP-10, IL-2, IL-18 and TNFα. IL-10, a cytokine previously investigated as an anticancer therapeutic, increased significantly by 1 hour (6.7X increase) and by 6 hours (84.5X increase) after treatment, before reverting to baseline levels by 48 hours. Despite large acute increases in specific cytokines, no changes to baseline levels over multiple treatment cycles were observed. Correlation analysis showed that baseline MCP-1 and MIP-1α levels were negatively correlated with overall survival; and the maximum change in concentration over the first dosage cycle of RANTES, IL-17F, Eotaxin, TGFα and MDC were positively correlated with overall survival. These results show that BOLD-100 in combination with FOLFOX can induce immune responses, and that these immune responses may predict clinical outcome. Analysis of additional patient samples from the Phase 2 trial is ongoing.

Citation Format: Mark Bazett, Brian Park, E Russell McAllister, Jim Pankovich. Novel metallotherapeutic BOLD-100 induces circulating cytokine changes when administered in combination with FOLFOX in advanced gastrointestinal cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2259.

Abstract 5489: Utilization of cancer cell line screening and bioinformatic analyses to identify optimal developmental pathways for the novel anticancer agent BOLD-100

Cell line screening of unique compounds can provide mechanistic insights and identify optimal drug combination partners. Bioinformatics analysis of cell screen data and correlation to publicly available datasets can support identification of appropriate patient populations for subsequent preclinical and clinical development. BOLD-100 is a first-in-class ruthenium-based anticancer agent currently being tested in a Phase 1b/2a clinical trial in combination with FOLFOX in the treatment of advanced gastrointestinal cancers. BOLD-100 works by altering the unfolded protein response through selective GRP78 inhibition; and inducing reactive oxygen species which causes DNA damage and cell cycle arrest. Collectively, these result in cell death in a range of different cancer types, and in combination with many different classes of anticancer agents. To determine optimal indications for BOLD-100 development, BOLD-100 was tested against 316 cancer cell lines in 72-hour Cell Titer Glo assays with downstream bioinformatic analysis and validation experiments. Multiple cancer types showed preferential response to BOLD-100, including bladder, esophageal, pancreatic, multiple myeloma and ovarian cancers. Subtype analysis identified potential populations of increased responsiveness, including in bladder cancer where BOLD-100 had increased response in luminal and mixed subtypes, as compared to basal subtypes. Utilizing bladder cancer as a case study, subsequent combination testing of BOLD-100 in combination with fluorouracil or cisplatin demonstrated that BOLD-100 enhanced cell death across different bladder cancer cell lines through synergistic interactions with these standard-of-care agents. The pan-cancer response profile of BOLD-100 was compared against 449 other anticancer drug responses that are part of the GDSC database. BOLD-100 displayed limited correlation with existing drugs, suggesting a unique mechanism of action and clinical utility where standard-of-care agents have limited efficacy. Pharmacogenomic analysis of the cell screen data indicated potential pathways and genes of relevance to BOLD-100 response, including increased response in KRAS-mutant cancers. Collectively, BOLD-100 showed a unique sensitivity profile across a panel of over 300 cancer cell lines, identifying multiple potential indications for future development. Subsequent investigations into several cancer types of interest and drug combinations are ongoing.

Citation Format: Paromita Raha, Brian Park, Adam Carie, Jim Pankovich, Mark Bazett. Utilization of cancer cell line screening and bioinformatic analyses to identify optimal developmental pathways for the novel anticancer agent BOLD-100 [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 5489.

BOLD-100-001 (TRIO039): A phase 1b dose-escalation study of BOLD-100 in combination with FOLFOX chemotherapy in patients with advanced gastrointestinal solid cancers: Interim safety, tolerability, and efficacy

3031

Background: BOLD-100 is a first-in-class ruthenium-based anticancer agent in Phase 1b / 2 clinical development for the treatment of advanced gastrointestinal (GI) cancers in combination with FOLFOX. Being developed primarily as a combinational agent, BOLD-100 induces cellular stress through modulation of the unfolded protein response, production of reactive oxygen species and induction of DNA damage. BOLD-100 demonstrates synergy in established preclinical models in combination with various anticancer therapies, particularly in resistant cell lines. Methods: This is a prospective, Phase 1b dose-escalation (Part A) and Phase 2 dose-expansion (Part B) study of BOLD-100 in combination with FOLFOX for colorectal (CRC), pancreatic (PDAC), gastric (GC) and biliary tract (BTC) cancers. Patients (pts) receive BOLD-100 with FOLFOX on day 1 of each 14-day cycle. In Part A, pts are enrolled in a 3+3 design to determine the combination recommended Phase 2 dose (RP2D), with BOLD-100 dose-escalation (420, 500 and 625 mg/m2) up to dose level 3. Part B comprises 5 cohorts treated at the RP2D until progressive disease or unacceptable toxicity. In Part A, reported here, the primary endpoints are safety, tolerability and maximum tolerated dose; the Part B endpoints are efficacy (primary), pharmacokinetic (PK) and pharmacodynamic parameters (secondary), and duration of response (exploratory) (NCT04421820). Results: As of 07 Feb 2022 (contains Part A preliminary data), 19 pts (mean age 65 years) were treated: 9 (47%) CRC, 5 (26%) BTC, 4 (21%) PDAC, 1 (5%) GC. Patients had a median of 3 prior systemic therapies, and 18 (95%) were enrolled with stage IV disease. Median number of cycles completed was 5 (range 1-15). 18 pts reported ≥1 treatment-emergent adverse events (AEs), most commonly fatigue (n = 12, 63%), nausea (n = 9, 47%) and stomatitis (n = 8, 42%). The majority of AEs were grade (G) 1-2. 7 G4 AEs (all neutropenia), and 1 unrelated G5 AE of pulmonary embolism occurred. There were 8 serious AEs in 6 different pts, with 1 SAE of dyspnea reported as related to BOLD-100. 2 pts experienced infusion-related reactions, related to chemotherapy. 2 dose-limiting toxicities have been observed: G3-4 neutropenia complicated by fever > 38.5°C or infection (n = 1, cohort #2) and inability to receive planned doses due to AEs (n = 1, cohort #3). To date for evaluable pts (n = 16), disease control rate of 75%, 1 partial response (48% target lesion reduction) and 11 stable disease have been observed. Conclusions: BOLD-100 plus FOLFOX is well-tolerated with no clinically significant safety findings. Dose-escalation data supports a BOLD-100 RP2D of 625 mg/m2 for the expansion phase. Progression-free survival, overall survival, and PK data are forthcoming. Clinical trial information: NCT04421820.

CRAFT-A Proposed Framework for Decentralized Clinical Trials Participation in Canada

Canada's vast geography, and centralized delivery of cancer care and clinical trials create barriers for trial participation for patients in remote and rural settings. The development and implementation of a framework that enables safe and regulatory compliant trial participation through local healthcare providers would benefit Canadian patients, clinicians, trial sponsors and the health care system. To address this issue, representatives of Canada's cancer clinical trial community met to identify key challenges and develop recommendations for remote patient participation in trials. A structured literature review identified remote/rural trial delivery models. A panel of expert stakeholders reviewed the models and participated in a workshop to assess health system readiness, identify needed processes, tools and mechanisms, and develop recommendations for a Canadian framework for decentralized clinical trial conduct. The Canadian Remote Access Framework for clinical Trials (CRAFT) represents a risk-based approach used by site investigators to delegate responsibilities for a given trial to satellite health centres within a hub-and-spoke "trial cluster". The Framework includes specific recommendations to ensure research experience, capacity, regulatory compliance and patient safety. Canada's cancer care and telemedicine systems can be leveraged to enable broader access to clinical trials for patients who are geographically remote from cancer centres. CRAFT's risk-based framework is based on other successful models of remote trial patient management and is in the pilot implementation phase in Canada.

Abstract 1183: Targeting the DNA repair pathway with BOLD-100 in BRAF mutant colorectal cancer

Background: BRAF mutations (BRAFMT) occur in ∼10-15% of metastatic colorectal cancer (mCRC) and have a poor clinical outcome, in particular those with microsatellite stable (MSS) disease. Anti-BRAF/EGFR combinations have shown some increases in response rate, but this is associated with minor increases in overall survival. There is an unmet need to understand the biology of poor prognostic BRAFMT CRC. Using publicly available gene expression data from 155 CRC cell lines (GSE59857), we recently identified that unfolded protein response (UPR) and DNA repair are dominant pathways deregulated in the consensus molecular subgroup 1/BRAFMT subgroup. The aim of this study was to investigate the role of BOLD-100, an inhibitor of the UPR regulator GRP78, in regulating the survival of CRC cells.

Methods: A panel of isogenic paired and non-isogenic V600E BRAFMT and BRAFWT cells were used. BOLD-100, a ruthenium-based small molecule inhibitor, was obtained from BOLD Therapeutics. Cell Titre Glo, Flow Cytometry, Western blotting, Caspase 8, 3/7 activity, RNAi assays were used. RNA seq and IPA bioinformatic analyses were performed on BOLD-100-treated BRAFMT/WT CRC cells. A compound library including small molecules approved by the FDA was used.

Results: In vitro CellTitre-Glo® and Annexin V/PI sensitivity studies showed that the BRAFMT, MSS CRC cells were highly sensitive to BOLD-100 with IC50 values between 9.25-31μM. Treatment with BOLD-100 resulted in early decreases in GRP78 levels and increases in expression levels of the endoplasmic reticulum stress protein CHOP, and this was associated with caspase-8 dependent cell death in the BRAFMT CRC cells. Notably, silencing of CHOP did not abrogate BOLD-100-induced cell death in BRAFMT CRC cells, indicating that the UPR pathway played no role in the cell death following BOLD-100. RNA seq and IPA analysis showed that cell cycle regulation and DNA repair were the most significant deregulated pathways following BOLD-100 treatment. Further mechanistic studies revealed that BOLD-100 induced rapid and potent increases in pATRT1989, pChk1S345 and γH2AX expression levels in BRAFMT cells. Using a small molecule compound library, we found that the ATR inhibitors AZD6783 and M4344 resulted in strong synergy and apoptosis when combined with BOLD-100, in particular in BRAFMT CRC cells. Moreover, we found that the ROS scavenger NAC abrogated BOLD-100 induced CHOP, pATRT1989, pChk1S345 and γH2AX levels and rescued cell death following BOLD-100 treatment in BRAFMT CRC cells.

Conclusions: Taken together, we have identified a role for BOLD-100 in regulating the survival of BRAFMT CRC cells. Our data support further studies with BOLD-100, in particular in combination with ATRi, for the treatment of BRAFMT CRC tumours.

Citation Format: Robbie Carson, Shivaali Karelia, Deborah Lavin, Vijay Tiwari, Richard Kennedy, Kienan Savage, Adam Carie, Jim Pankovich, Mark Bazett, Sandra Van Schaeybroeck. Targeting the DNA repair pathway with BOLD-100 in BRAF mutant colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1183.

BOLD-100-001 (TRIO039): A phase Ib dose-escalation study of BOLD-100 in combination with FOLFOX chemotherapy in patients with advanced gastrointestinal solid tumors

TPS145

Background: Although most cancers are initially susceptible to existing anticancer therapies, over time cancer cells develop resistance. BOLD-100 is a first-in-class therapy that targets the GRP78 pathway, a major regulator of cellular stress and resistance. This therapy suppresses drug resistance, survival and proliferation by restraining stress-induced upregulation of GRP78 in tumor cells, leading to inhibition of the cell survival response. BOLD-100 successfully completed a Phase 1 monotherapy trial, with a manageable safety profile; it has demonstrated synergy in established preclinical models in combination with a wide variety of anticancer therapies and shown to restore sensitivity of drug-resistant cell lines. Methods: BOLD-100-001 is a multicenter, prospective, two-stage, non-randomized Phase 1b dose escalation and expansion study of BOLD-100 in combination with FOLFOX chemotherapy for selected advanced solid gastrointestinal (GI) tumors: colorectal (CRC), pancreatic (PANC), gastric (GC) and bile duct cancers (BDC). Each patient will receive BOLD-100 along with FOLFOX chemotherapy on Day 1 of each 14-day cycle. In the dose-escalation phase (Part A), patients will be enrolled to determine the combination recommended dose using a standard 3+3 design. In the dose-expansion phase (Part B), up to 80 patients with selected GI tumors will be enrolled in 5 cohorts (comprising the 4 GI cancers referred) and treated with BOLD-100 at the recommended dose and FOLFOX, until progressive disease or unacceptable toxicity. In Part A dose-escalation, the primary objective is to assess the safety, tolerability and maximum tolerated dose. The Part B dose-expansion will assess the efficacy (progression free survival, overall survival and response rate), of FOLFOX chemotherapy plus BOLD-100. Secondary objectives in Part A and B include the assessment of pharmacokinetic and pharmacodynamic parameters and potential biomarkers predictive of efficacy. Eligible patients will have previously treated histologically/cytologically confirmed metastatic/unresectable GI tumor (CRC, PANC, GC or BDC), measurable disease per RECIST criteria, an ECOG performance score of 0 or 1, and adequate organ function. In Part A, no formal statistical hypotheses will be tested; analysis of the data will focus on comparisons of safety and dose-limiting toxicities between cohorts and only descriptive methods will be used. In Part B, Bayesian modelling will be used to continually reassess the efficacy endpoints: progression free survival, overall survival and objective response rates. The study was opened for enrollment in August 2020; approximately 25-30 patients will be screened to achieve up to 20 patients in Part A and up to 80 patients will be enrolled in Part B with a maximum of 25 patients per arm. Clinical trial information: NCT04421820.

Novel Microbial-Based Immunotherapy Approach for Crohn's Disease

Background: Current Crohn's disease (CD) therapies focus on suppressing immune function and come with consequent risk, such as infection and cancer. Notwithstanding, most CD patients still experience disease progression. There is a need for new CD treatment strategies that offer better health outcomes for patients.

Aims: To assess safety, efficacy, and tolerability of a novel microbial-derived immunotherapy, QBECO, that aims to restore rather than suppress immune function in CD.

Methods: A randomized, double-blind, placebo-controlled trial was conducted in 68 patients with moderate-to-severe CD. Primary endpoints: safety and Week 8 clinical improvement. Secondary endpoints: Week 8 clinical response and remission. Week 8 responders continued blinded treatment through Week 16; non-responders received open-label QBECO from Weeks 9–16. Exploratory analyses included immune biomarker and genotype assessments.

Results: QBECO was well-tolerated. Mean reduction in Crohn's Disease Activity Index (CDAI) score was −68 for QBECO vs. −31 for placebo at Week 8. Improvement with QBECO continued through Week 16 (-130 CDAI reduction). Week 8 QBECO clinical response, improvement and remission rates were 41.2%, 32.4%, 29.4% vs. 26.5%, 23.5%, 23.5% for placebo. TNFα inhibitor-naïve subjects achieved higher response rates at Week 8 with QBECO (64%) vs. placebo (26%). Specific immune biomarkers were identified that linked to QBECO response.

Conclusion: This proof-of-concept study supports further investigation for the use of QBECO as a novel immunotherapy approach for CD. Biomarker analyses suggests it may be feasible to personalize CD treatment with QBECO. Larger trials are now needed to confirm clinical improvement and the unique biological findings.

Clinical Trial Number: NCT01809275 (https://clinicaltrials.gov/ct2/show/NCT01809275)

Immune Stimulation Using a Gut Microbe-Based Immunotherapy Reduces Disease Pathology and Improves Barrier Function in Ulcerative Colitis

Background: Current ulcerative colitis (UC) treatments are focused on symptom management primarily via immune suppression. Despite the current arsenal of immunosuppressant treatments, the majority of patients with UC still experience disease progression. Importantly, aggressive long-term inhibition of immune function comes with consequent risk, such as serious infections and malignancy. There is thus a recognized need for new, safe and effective treatment strategies for people living with UC that work upstream of managing the symptoms of the disease. The objective of this study was to evaluate a microbial-based treatment, QBECO, that functions to productively activate rather than suppress mucosal immune function as a novel approach to treat UC. Methods: Two established models of experimental colitis, namely chemically-induced DSS colitis and the spontaneous colitis that develops in Muc2 deficient mice, were used to assess whether QBECO treatment could ameliorate gastrointestinal disease. A small exploratory 16-week QBECO open-label trial was subsequently conducted to test the safety and tolerability of this approach and also to determine whether similar improvements in clinical disease and histopathology could be demonstrated in patients with moderate-to-severe UC. Results: QBECO treatment successfully reduced inflammation and promoted mucosal and histological healing in both experimental models and in UC patients. The preclinical models of colitis showed that QBECO ameliorated mucosal pathology, in part by reducing inflammatory cell infiltration, primarily that induced by neutrophils and inflammatory T cells. The most rapid and noticeable change observed in QBECO treated UC patients was a marked reduction in rectal bleeding. Conclusion: Collectively, this work demonstrates for the first time that strategically activating immune function rather than suppressing it, not only does not worsen colitis induced-damage, but may lead to an objective reduction in UC disease pathology.

Harnessing innate lung anti-cancer effector functions with a novel bacterial-derived immunotherapy

Acute infection is known to induce strong anti-tumor immune responses, but clinical translation has been hindered by the lack of an effective strategy to safely and consistently provoke a therapeutic response. These limitations are overcome with a novel treatment approach involving repeated subcutaneous delivery of a Klebsiella-derived investigational immunotherapeutic, QBKPN. In preclinical models of lung cancer, QBKPN administration consistently showed anti-cancer efficacy, which was dependent on Klebsiella pre-exposure, but was independent of adaptive immunity. Rather, QBKPN induced anti-tumor innate immunity that required NK cells and NKG2D engagement. QBKPN increased NK cells and macrophages in the lungs, altered macrophage polarization, and augmented the production of cytotoxic molecules. An exploratory trial in patients with non-small cell lung cancer demonstrated QBKPN was well tolerated, safe, and induced peripheral immune changes suggestive of macrophage polarization and reduction of PD-1 and PD-L1 expression on leukocytes. These data demonstrate preclinical efficacy, and clinical safety and tolerability, for this cancer immunotherapy strategy that exploits innate anti-tumor immune mechanisms.

Intensifying Antiretroviral Therapy With Raltegravir and Maraviroc During Early Human Immunodeficiency Virus (HIV) Infection Does Not Accelerate HIV Reservoir Reduction

Background. Persistent human immunodeficiency virus (HIV) within the CD4⁺ T-cell reservoir is an obstacle to eradication. We hypothesized that adding raltegravir and maraviroc to standard combination antiretroviral therapy (cART) during early HIV infection could substantially reduce viral reservoirs as a step towards eradication.

Methods. A prospective, randomized, double-blinded, placebo-controlled pilot trial enrolled 32 participants with documented early (<6 months) HIV infection to either standard cART (emtricitabine/tenofovir/lopinavir/ritonavir) or intensive cART (standard regimen + raltegravir/maraviroc). Human immunodeficiency virus reservoirs were assessed at baseline and at 48 weeks by (1) proviral DNA, (2) cell-associated RNA, and (3) replication-competent virus, all from purified blood CD4⁺ T cells, and (4) gut proviral DNA. A multiassay algorithm (MAA) on baseline sera estimated timing of infection.

Results. Thirty individuals completed the study to the 48-week endpoint. The reduction in blood proviral burden was −1.03 log DNA copies/10⁶ CD4⁺ T cells versus −.84 log in the standard and intensive groups, respectively (P = .056). Overall, there was no significant difference in the rate of decline of HIV-associated RNA, replication-competent virus in blood CD4⁺ T cells, nor proviral gut HIV DNA to 48 weeks. Individuals who presented with more recent HIV infection had significantly lower virus reservoirs, and cART tended to reduce their reservoirs to a greater extent.

Conclusions. Intensive cART led to no additional reduction in the blood virus reservoir at 48 weeks compared with standard cART. Human immunodeficiency virus reservoir size is smaller earlier in HIV infection. Other novel treatment strategies in combination with early cART will be needed to eliminate the HIV latent reservoir.

Gender disparities in HIV risk behavior and access to health care in St. Petersburg, Russia

Over 40,000 HIV-infected individuals live in St Petersburg, Russia. Population characteristics and barriers to care are largely undefined. 152 consecutive patients receiving HIV care at two sites completed a questionnaire in Spring 2011. Rates of chronic hepatitis C virus (HCV) and hepatitis B virus (HBV) infection, alcohol use, and rates of antiretroviral uptake were similar by gender. Males reported a higher history of injection drug use (80.3% vs. 48.7%; p<0.01) and tuberculosis infection (18.8% vs. 1.6%; p<0.01). Females were more likely to have had a child (63.3% vs. 31.5%; p<0.01) and be currently raising that child within their residence (49.3% vs. 15.3%; p<0.01). Unprotected sex (60.5% vs. 17.8%; p<0.01) and a history of sexually transmitted infection (37.7% vs. 20.3%; p=0.03) were more common in females. Females utilized social services more frequently (34.2% vs. 11.9%; p<0.01). There is a heavy burden of concurrent infectious disease, substance use and abuse, mental health illness, and need for social service support in this population. Important differences exist between genders in service uptake and utilization. Further evaluation of these differences may help inform the allocation of limited resources in this high HIV prevalence region of Russia.

Umbilical arterial blood flow and plasma prostaglandin E2 concentrations during arousal and breathing movements in fetal sheep

To investigate the effects of lung distension and oxygenation on umbilical blood flow (UBF) and plasma prostaglandin E2 (PGE2) in relation to arousal and stimulation of breathing movements, we studied eight chronically instrumented, unanesthetized fetal sheep between 137 and 143 d of gestation. Electrocorticogram, electro-oculogram, nuchal and diaphragmatic electromyograms, arterial pH and blood gas tensions, Hb oxygen saturation, body temperature, and UBF were recorded in each fetus. Electrocorticogram, electro-oculogram, and nuchal electromyograms were used to define sleep states. No sooner than 4 d after surgery, fetal lungs were distended with 100% O2 or N2 in a randomized order via an in situ Y-endotracheal tube. PGE2 concentrations were analyzed by RIA. A significant increase in fetal arousal and stimulation of breathing during nonrapid eye movement sleep was observed during lung distension with O2 as compared with control periods and lung distension with nitrogen. In all sleep states, UBF significantly decreased during oxygenation as compared with the control values. However, no significant correlation was observed between the time of the onset of arousal and the decrease in UBF. Lung distension with N2 resulted in increased plasma PGE2 concentrations, whereas, no change was observed during oxygenation. Our data suggest that an increase in fetal partial pressure of arterial O2 leads to a decrease in UBF. However, the onset of arousal and stimulation of breathing during lung distension and oxygenation were not dependent on a decrease in plasma PGE2 concentrations.

Exploitation of pigment biosynthesis pathway as a selective chemotherapeutic approach for malignant melanoma

Human malignant melanoma represents a difficult therapeutic challenge to both medical scientists and practicing physicians. However, the biologic uniqueness of the tumor may provide opportunities for exploitation in therapeutics. This study proposed to undertake a systemic approach to the chemotherapy of malignant melanoma based upon the uniqueness of pigment-cell metabolic pathway pertaining to conversion of tyrosine and dopa with subsequent formation of melanin by tyrosinase and its related enzymes. The sulphur homologue of tyrosine, cysteinylphenol (CP), its amine derivative, cysteaminylphenol (CAP), and their N-acetyl and alpha-methyl derivatives have been synthesized and tested in in vivo and in vitro melanocytotoxicity and antimelanoma effects. These phenolic thioethers (PTEs) and phenolic thioether amine (amides) (PTEAs), which are substrates of tyrosinase, showed significant cytotoxicity that is selective to melanocytes and melanoma cells. Most previous attempts to impair the melanin pathway as a therapeutic strategy have been of limited success because they have been directed to catecholic compounds that are unstable and insufficient in lethality at physiologically tolerable doses. By contrast, our approach relies on phenolic compounds, PTEs and PTEAs, which are more stable than catechols and become toxic only after oxidation by tyrosinase. We found PTEA as the most promising agent for the future development of chemotherapeutic agents. The possible biologic, chemical, and pharmacologic reactions of these synthetic compounds within the melanoma cells are studied and discussed.