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We sought to determine racial and ethnic differences in perceptions (quality of communication, expectations, and concerns) of germline or somatic DNA sequencing (genomic profiling). Patients with prostate, urothelial, or kidney cancer were surveyed using a questionnaire that assessed previous experience, beliefs, expectations, and concerns regarding genomic profiling. Descriptive statistics and chi-square tests were used to identify factors associated with patients' perceptions of genomic profiling. A total of 150 consecutive patients were enrolled. The majority were male (74%) with a mean age of 68 years old. Most patients underwent somatic testing (54%), 24% undertook germline testing, and 21% undertook both tests. Significant differences were found across racial and/or ethnicity concerning factors that could have influenced patients' decision to pursue genomic profiling, including ability to guide the type of treatment (White: 54.1% vs. other ethnic groups: 43.9%, p = 0.04) and potential to improve treatment response (White: 10.1% vs. other ethnic groups: 22.0%, p = 0.04). Other ethnic group of patients were more concerned about learning that the cancer was less treatable or aggressive (43.8% vs. 27.7%, p = 0.01) and anxious about what would be learnt from genomic profiling (34.4% vs. 21.3, p = 0.01) as compared to White patients. Our findings reinforce the importance of developing culturally tailored education to help patients participate actively in decisions about genomic profiling., (© 2023 National Society of Genetic Counselors.)

Background: We explored changes in perceptions of cure among patients with genitourinary (GU) cancers starting Immune checkpoint inhibitors (ICIs) therapy., Materials and Methods: This longitudinal study assessed patients before starting therapy and 3-months later with a questionnaire that included patient perceptions of ICIs and the Patient-Reported Outcomes Measurement Information System (PROMIS) Anxiety scale. General linear modeling was used to investigate changes in expectation of cure over time, and chi-square tests were used to determine the association between expectation of cure and perceptions of ICIs and anxiety., Results: A total of 45 patients were recruited (73% male, 84% diagnosed with renal cell carcinoma). The proportion of patients who possessed an accurate expectation of cure increased over time (55.6%-66.7%, P = .001). An accurate expectation of cure was associated with lower rates of anxiety over time. Patients with inaccurate expectation of cure reported more severe side effects and worse self-reported ECOG score at the follow-up assessment (P = .04)., Conclusion: We found that patients with GU metastatic cancer treated with ICI therapy have increasingly accurate expectations of cure over time. Accurate expectation of cure is associated with decreased anxiety. Further research is needed to fully explore this dynamic over time and help inform interventions that can help patients develop accurate expectations., Competing Interests: Disclosure All authors declare that they have no potential conflicts of interest for this work., (Copyright © 2023. Published by Elsevier Inc.)

In this age of data, digital tools are widely promoted as having tremendous potential for enhancing food safety. However, the potential of these digital tools depends on the availability and quality of data, and a number of obstacles need to be overcome to achieve the goal of digitally enabled "smarter food safety" approaches. One key obstacle is that participants in the food system and in food safety often lack the willingness to share data, due to fears of data abuse, bad publicity, liability, and the need to keep certain data (e.g., human illness data) confidential. As these multifaceted concerns lead to tension between data utility and privacy, the solutions to these challenges need to be multifaceted. This review outlines the data needs in digital food safety systems, exemplified in different data categories and model types, and key concerns associated with sharing of food safety data, including confidentiality and privacy of shared data. To address the data privacy issue a combination of innovative strategies to protect privacy as well as legal protection against data abuse need to be pursued. Existing solutions for maximizing data utility, while not compromising data privacy, are discussed, most notably differential privacy and federated learning.

Background: Vaccinations against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have had a transformative impact on morbidity and mortality. However, the long-term impact of vaccination on patients with genitourinary cancers is currently unknown., Materials and Methods: This study aimed to assess seroconversion rates in patients with genitourinary cancers receiving COVID-19 vaccination. Patients with prostate cancer, renal cell carcinoma, or urothelial cancer who had not been vaccinated for COVID-19 were included. Blood samples were obtained at baseline and after 2, 6, and 12 months of one dose of an FDA-approved COVID-19 vaccine. Antibody titer analysis was performed using the SCoV-2 Detect IgG ELISA assay, and the results were reported as immune status ratio (ISR). A paired t-test was used for comparison of ISR values between timepoints. In addition, T-cell receptor (TCR) sequencing was performed to assess for differences in TCR repertoire 2 months after vaccination., Results: Out of 133 patients enrolled, 98 baseline blood samples were collected. At 2-, 6-, and 12-month time points 98, 70, and 50 samples were collected, respectively. Median age was 67 (IQR, 62-75), with the majority of patients diagnosed with prostate (55.1%) or renal cell carcinoma (41.8%). Compared to baseline (0.24 [95% CI, 0.19-0.31]) a significant increase in the geometric mean ISR values was observed at the 2-month timepoint (5.59 [4.76-6.55]) (P < .001). However, at the 6-month timepoint, a significant decrease in the ISR values was observed (4.66 [95% CI, 4.04-5.38]; P < .0001). Notably, at the 12-month timepoint, the addition of a booster dose resulted in an absolute increase in the ISR values compared to those who did not receive a booster dose (P = .04)., Conclusions: Only a minority of patients with genitourinary cancers did not ultimately achieve satisfactory seroconversion after receiving commercial COVID-19 vaccination. Cancer type or treatment rendered did not appear to affect the immune response mounted after vaccination., (© The Author(s) 2023. Published by Oxford University Press.)

Stereotactic body radiation therapy (SBRT) has been shown to be safe and effective for delaying systemic treatment change among patients with metastatic renal cell carcinoma (mRCC). In this study, we sought to assess the genomic signatures of patients with mRCC who underwent SBRT for oligoprogression. A total of 30 patients with oligoprogressive disease were identified, the majority of whom had clear cell renal cell carcinoma (83.3%) and were receiving first-line treatment (53.3%). Genomic and transcriptomic sequencing were available in 20 and 16 patients, respectively. Duration of systemic treatment (DOT) was categorized as that prior (DOT[P]) and subsequent (DOT[S]) to radiation treatment. The median DOT(P) and DOT(S) were 15.1 and 18.3 mo, respectively, with a median DOT(S)/DOT(P) ratio of 1.4. Patients who had a DOT(S)/DOT(P) ratio of ≥1 had increased expression in pathways related to cell proliferation and development. In contrast, among patients with a ratio of ≤1, the reactive oxygen species pathway was enriched. This study highlights the potential role of genomics and transcriptomics to refine radiation treatment selection in patients with mRCC. PATIENT SUMMARY: In this study, we looked at mutations and genomic expressions among kidney cancer patients who responded better to stereotactic body radiotherapy. We found that enriched expression of certain pathways might play a role in response to radiotherapy., (Copyright © 2022. Published by Elsevier B.V.)

Previous studies have suggested that the gut microbiome influences the response to checkpoint inhibitors (CPIs) in patients with cancer. CBM588 is a bifidogenic live bacterial product that we postulated could augment CPI response through modulation of the gut microbiome. In this open-label, single-center study (NCT03829111), 30 treatment-naive patients with metastatic renal cell carcinoma with clear cell and/or sarcomatoid histology and intermediate- or poor-risk disease were randomized 2:1 to receive nivolumab and ipilimumab with or without daily oral CBM588, respectively. Stool metagenomic sequencing was performed at multiple timepoints. The primary endpoint to compare the relative abundance of Bifidobacterium spp. at baseline and at 12 weeks was not met, and no significant differences in Bifidobacterium spp. or Shannon index associated with the addition of CBM588 to nivolumab-ipilimumab were detected. Secondary endpoints included response rate, progression-free survival (PFS) and toxicity. PFS was significantly longer in patients receiving nivolumab-ipilimumab with CBM588 than without (12.7 months versus 2.5 months, hazard ratio 0.15, 95% confidence interval 0.05-0.47, P = 0.001). Although not statistically significant, the response rate was also higher in patients receiving CBM588 (58% versus 20%, P = 0.06). No significant difference in toxicity was observed between the study arms. The data suggest that CBM588 appears to enhance the clinical outcome in patients with metastatic renal cell carcinoma treated with nivolumab-ipilimumab. Larger studies are warranted to confirm this clinical observation and elucidate the mechanism of action and the effects on microbiome and immune compartments., (© 2022. The Author(s).)

Purpose: The role of circulating cell-free tumor DNA (ctDNA) as an adjunct to tissue genomic profiling is poorly defined in metastatic renal cell carcinoma (mRCC). In this study, we aim to validate previous findings related to genomic alteration (GA) frequency in ctDNA and determine the concordance between ctDNA and tissue-based profiling in patients with mRCC., Experimental Design: Results of 839 patients with mRCC who had ctDNA assessment with a Clinical Laboratory Improvement Amendments (CLIA)-certified ctDNA assay between November 2016 and December 2019 were collected. Tissue-based genomic profiling was collected when available and concordance analysis between blood- and tissue-based testing was performed., Results: ctDNA was assessed in 839 patients (comprising 920 samples) with mRCC. GAs were detected in 661 samples (71.8%). Tissue-based GAs were assessed in 112 patients. Limiting our analyses to a common 73-/74-gene set and excluding samples with no ctDNA detected, a total of 228 mutations were found in tissue and blood. Mutations identified in tissue (34.7%; 42/121) were also identified via ctDNA, whereas 28.2% (42/149) of the mutations identified in liquid were also identified via tissue. Concordance between ctDNA and tissue-based profiling was inversely related to the time elapsed between these assays., Conclusions: This study confirms the feasibility of ctDNA profiling in the largest mRCC cohort to date, with ctDNA identifying multiple actionable alterations. It also demonstrates that ctDNA and tissue-based genomic profiling are complementary, with both platforms identifying unique alterations, and confirms that the frequency of unique alterations increases with greater temporal separation between tests., (©2021 American Association for Cancer Research.)

Background: Tertiary cancer centers offer clinical expertise and multi-modal approaches to treatment alongside the integration of research protocols. Nevertheless, most patients receive their cancer care at community practices. A better understanding of the relationships between tertiary and community practice environments may enhance collaborations and advance patient care., Methods: A 31-item survey was distributed to community and tertiary oncologists in Southern California using REDCap. Survey questions assessed the following attributes: demographics and features of clinical practice, referral patterns, availability and knowledge of clinical trials and precision medicine, strategies for knowledge acquisition, and integration of community and tertiary practices., Results: The survey was distributed to 98 oncologists, 85 (87%) of whom completed it. In total, 52 (61%) respondents were community practitioners and 33 (38%) were tertiary oncologists. A majority (56%) of community oncologists defined themselves as general oncologists, whereas almost all (97%) tertiary oncologists reported a subspecialty. Clinical trial availability was the most common reason for patient referrals to tertiary centers (73%). The most frequent barrier to tertiary referral was financial considerations (59%). Clinical trials were offered by 97% of tertiary practitioners compared to 67% of community oncologists (p = 0.001). Most oncologists (82%) reported only a minimal-to-moderate understanding of clinical trials available at regional tertiary centers., Conclusions: Community oncologists refer patients to tertiary centers primarily with the intent of clinical trial enrollment; however, significant gaps exist in their knowledge of trial availability. Our results identify the need for enhanced communication and collaboration between community and tertiary providers to expand patients' access to clinical trials., (© 2021 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.)

Background: Circulating cytokines and angiogenic factors have been associated with clinical outcomes in patients with metastatic renal cell carcinoma (RCC) receiving systemic therapy. However, none have yet examined cytokine concentrations in parallel cohorts receiving either immunotherapy or targeted therapy., Methods: In this prospective correlative study, we enrolled 56 patients who were planned for treatment with either a vascular endothelial growth factor-tyrosine kinase inhibitor (VEGF-TKI) or immune checkpoint inhibitor (ICI). Eligibility requirements permitted any RCC histologic subtype, International Metastatic Renal Cell Carcinoma risk classification, and line of therapy. Immunologic profile was assessed at baseline and after 1 month on treatment using a Human Cytokine 30-plex protein assay (Invitrogen). Clinical benefit was defined as complete response, partial response, or stable disease ≥6 months per RECIST (Response Evaluation Criteria in Solid Tumors) V.1.1 criteria., Results: Clinical benefit was similar between VEGF-TKI and ICI arms (65% vs 54%). Patients with clinical benefit from VEGF-TKIs had lower pretreatment levels of interleukin-6 (IL-6) (p=0.02), IL-1RA (p=0.03), and granulocyte colony-stimulating factor (CSF) (p=0.02). At 1 month, patients with clinical benefit from ICIs had higher levels of interferon-γ (IFN-γ) (p=0.04) and IL-12 (p=0.03). Among patients on VEGF-TKIs, those with clinical benefit had lower 1 month IL-13 (p=0.02) and granulocyte macrophage CSF (p=0.01) as well as higher 1 month VEGF (p=0.04) compared with patients with no clinical benefit., Conclusion: For patients receiving VEGF-TKI or ICI therapy, distinct plasma cytokines were associated with clinical benefit. Our findings support additional investigation into plasma cytokines as biomarkers in metastatic RCC., Competing Interests: Competing interests: SP reports consulting roles in Genentech, Aveo, Eisai, Roche, Pfizer, Novartis, Exelixis, Ipsen, BMS, and Astellas. ACR, LM, MA, ND, PB, NS, JH, NR, EK, and MK declare no conflicts of interest., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Objectives: To better characterize the relay of information about prostate, kidney, and bladder cancer on Twitter in relation to the COVID-19 pandemic., Materials and Methods: Tweets containing the joint hashtags "#COVID-19" and either "#bladder cancer", "#kidney cancer", or "#prostate cancer" were identified on the Twitter platform from January 1, 2020 to July 30, 2020. The Twitter handle responsible for each tweet was categorized as an Academic, Medical Education, Patient Advocacy Groups/Non-Profits, Pharmaceutical, or Other entity based on content domain. Descriptive statistics were used to summarize data on Twitter handle characteristics stratified by disease category (bladder, kidney, and prostate). Median/interquartile range and percentages were used to summarize continuous and categorical data, respectively. Number of tweets containing the relevant joint hashtags were tracked over time in relation to the cumulative United States case count of COVID-19., Results: The content of 730 total tweets containing the joint hashtags "COVID-19" and either "#bladder cancer" (138 tweets), "#kidney cancer" (137 tweets), or "#prostate cancer" (455 tweets) from January 1, 2020 to July 31, 2020 were analyzed. We identified 326 unique Twitter handles across all disease states (62 bladder, 47 kidney, and 217 prostate-related). Academic Twitter handles accounted for the greatest number of tweets containing the joint hashtags (31%). Temporal tracking of tweets with regard to monthly U.S. COVID cases revealed that communication surged in March of 2020 and peaked in April for both bladder and kidney cancer, whereas related prostate cancer Twitter communication peaked in May of 2020., Conclusions: As COVID-19 case counts rose in the United States initially, so too did communication surrounding COVID-19 and genitourinary cancers on Twitter. Many of these conversations were driven by academically-associated Twitter accounts., Competing Interests: CONFLICTS OF INTEREST Sabrina Salgia, Nicholas Salgia, Sweta Prajapati, Ishaan Seghal, Frank Bautista, Nora Ruel, Meghan Salgia, and Deborah A. Salgia have no conflicts of interest that might be relevant to the contents of this manuscript. Ravi Salgia, MD, PhD: Consulting or Advisory Role: Janssen, AstraZeneca, Novartis, Merck. Sumanta K. Pal, MD: Honoraria: Novartis, Medivation, Astellas Pharma; Consulting or Advisory Role: Pfizer, Novartis, Aveo, Myriad; Pharmaceuticals, Genentech, Exelixis, Bristol-Myers Squibb, Astellas Pharma; Research Funding: Medivation.

Within the past decade, immunotherapy has revolutionized the treatment of advanced non-small lung cancer (NSCLC). Immune checkpoint inhibitors (ICIs) such as pembrolizumab, nivolumab, atezolizumab, and durvalumab have shown superiority over chemotherapy regimens in patients with programmed death-ligand 1 (PD-L1) expression. Several predictive molecular biomarkers, including PD-L1 expression and high tumor mutation burden, have shown utility in discovering lung cancer patient groups that would benefit from ICIs. However, there remains to be a reliable imaging biomarker that would clearly select patients, through baseline or restaging imaging, who would respond or have a prolonged response to ICIs. The purpose of this review is to highlight the role of ICIs in patients with advanced NSCLC and past or current studies in potential biomarkers as well as future directions on the role of imaging in immunotherapy., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at http://dx.doi.org/10.21037/jtd.2020.04.15). The series “Role of Precision Imaging in Thoracic Disease” was commissioned by the editorial office without any funding or sponsorship. EM has received honoraria from Astra Zeneca Pharmaceuticals, Merck & Co, and received research support from Pfizer, Astra Zeneca, Merck, BMS, GSK, and Tessa Pharmaceuticals. The other authors have no other conflicts of interest to declare., (2020 Journal of Thoracic Disease. All rights reserved.)

Introduction : Focal adhesion kinase (FAK) is a promising target for the treatment of solid tumors because its expression has been linked to tumor progression, invasion, and drug resistance. Several FAK inhibitors have been developed and tested for efficacy in treating advanced cancers. Four FAK inhibitors have shown promising preclinical data and have advanced to clinical development in solid tumors. Areas covered : This article provides a systematic review on FAK inhibitors that have been tested or are currently in clinical trials in advanced solid tumors. We discuss the efficacy of GSK2256098, PF-00562271, VS-6063, and BI 853520 in the preclinical setting and summarize the results of phase I/II clinical trials evaluating these compounds. Expert opinion : The FAK inhibitors examined in clinical trials thus far have been shown to have manageable toxicity profiles and have demonstrated cytostatic effects as single agents, extending progression-free survival without producing a clinical or radiographic response. Trials are currently underway to strengthen the efficacy of treatment by combining FAK inhibitors with cytotoxic chemotherapy, targeted therapy, or immunotherapy. In the future, prognostic markers must be identified to carefully select patients who could benefit from FAK inhibitor treatment alone or in combination strategies.

Introduction: Pituitary gigantism is a rare but significant paediatric condition with complexities surrounding diagnosis and management. Transsphenoidal surgery (TSS) is the treatment of choice; however, medical treatment is often considered as adjuvant therapy., Case: A 10½ -year-old boy presented with tall stature and a height velocity of 11 cm/year. His height was 178.7 cm (+5.8 SD above mean) and insulin-like growth factor-1 (IGF-1) was elevated. An oral glucose tolerance test demonstrated non-suppression of growth hormone (GH). Initial contrast MRI was inconclusive, but C-11 methionine functional positron emission tomography CT identified a 6 mm pituitary microadenoma. A multidisciplinary team clinic held with the family allowed discussion about medical and surgical treatment options. Due to a number of factors including the patient's young age, prepubertal status, a wish to allow him to settle into his new high school and his desire to reach a final height taller than his father's height, it was decided to try medical therapy first with a somatostatin analogue. Pubertal induction was also commenced and bilateral epiphysiodesis surgery performed. Initial response to octreotide was positive; however, 4 months into therapy his IGF-1 was climbing and a repeat GH profile was not fully suppressed. The patient therefore proceeded to have successful TSS excision of the adenoma., Conclusion: Rare cases such as this require sharing of knowledge and expertise, so the best possible care is offered. It is often necessary to work across sites and disciplines. Each case requires an individual approach tailored to the patient and their family., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

The treatment landscape for renal cell cancer (RCC) has evolved tremendously over the last two decades. Treatment algorithms have shifted from the highly toxic drugs with marginal benefit to better tolerated and more effective targeted therapy drugs. The latter include tyrosine kinase inhibitors, vascular endothelial growth factor inhibitors, MET inhibitors and, more recently, immunotherapy drugs alone and in various combinations. The majority of treatment algorithms for non-clear cell carcinoma have been based on extrapolating results from clear cell RCC trials and retrospective reviews. However, now that we understand that non-clear cell RCC is morphologically and clinically distinct from its clear cell counterpart, several collaborative clinical trials are underway for non-clear cell RCC. This review will delve into the historical aspects of treating non-clear cell RCC and the evolution of treatment paradigms over the last few decades with a focus on immunotherapy based trials., Competing Interests: Declaration of Competing Interest SG, EP, and SS have nothing to disclose. SKP reports personal fees from Pfizer, Novartis, AVEO, Myriad Genetics, Genentech, Exelixis, BMS, Astellas, and Medivation., (Copyright © 2020. Published by Elsevier Ltd.)

We present a patient with leptomeningeal carcinomatosis from breast cancer treated with intrathecal topotecan and intravenous eribulin. The regimen was well tolerated and provided clinical stability in a patient with progression on a prior intrathecal chemotherapy regimen., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Spt5p is a universally conserved transcription factor that plays multiple roles in eukaryotic transcription elongation. Spt5p forms a heterodimer with Spt4p and collaborates with other transcription factors to pause or promote RNA polymerase II transcription elongation. We have shown previously that Spt4p and Spt5p also influence synthesis of ribosomal RNA by RNA polymerase (Pol) I; however, previous studies only characterized defects in Pol I transcription induced by deletion of SPT4. Here we describe two new, partially active mutations in SPT5 and use these mutant strains to characterize the effect of Spt5p on Pol I transcription. Genetic interactions between spt5 and rpa49Δ mutations together with measurements of ribosomal RNA synthesis rates, rDNA copy number, and Pol I occupancy of the rDNA demonstrate that Spt5p plays both positive and negative roles in transcription by Pol I. Electron microscopic analysis of mutant and WT strains confirms these observations and supports the model that Spt4/5 may contribute to pausing of RNA polymerase I early during transcription elongation but promotes transcription elongation downstream of the pause(s). These findings bolster the model that Spt5p and related homologues serve diverse critical roles in the control of transcription.

The synthesis of ribosomes in eukaryotic cells is a complex process involving many nonribosomal protein factors and snoRNAs. In general, the processes of rRNA transcription and ribosome assembly are treated as temporally or spatially distinct. Here, we describe the identification of a point mutation in the second largest subunit of RNA polymerase I near the active center of the enzyme that results in an elongation-defective enzyme in the yeast Saccharomyces cerevisiae. In vivo, this mutant shows significant defects in rRNA processing and ribosome assembly. Taken together, these data suggest that transcription of rRNA by RNA polymerase I is linked to rRNA processing and maturation. Thus, RNA polymerase I, elongation factors, and rRNA sequence elements appear to function together to optimize transcription elongation, coordinating cotranscriptional interactions of many factors/snoRNAs with pre-rRNA for correct rRNA processing and ribosome assembly.

Nipecotamides (piperidine-3-carboxamides) are potent inhibitors of platelet aggregation induced by a variety of agonists in vitro and in vivo. The inhibitory effects of six structural types of nipecotamides on human platelet aggregation induced by platelet-activating factor (PAF) in vitro, are studied. Evaluation of 15 racemates and stereoisomers of two nipecotamides showed that bis-nipecotoyl alkanes were more active than their mono congeners. Mono- and bis-nipecotoyl decanes were more potent than the corresponding hexanes. Lipophilicity was found to play a significant role in the antiplatelet activity of these compounds. The stereoselectivity in the PAF-antagonist potential of nipecotamides was less pronounced than that resulting from their action on ADP- or collagen-induced aggregation. Oxidation of the two benzylic carbon atoms of alpha, alpha'-bis[3-(N,N-diethylcarbamoyl)piperidino]-p-xylene.2HBr (A-1) to form 1,4-bis[3-N,N-diethylcarbamoyl) piperidino]benzenedicarboxamide (A-40K), which has a second set of carbonyl oxygens but lacks basic N atoms, resulted in a remarkable loss of ADP-antagonist potency while retaining PAF-antagonist activity. It is suggested that in addition to their membrane effects, nipecotamides act at other sites, including the PAF receptor. Double reciprocal plots of PAF binding to gel-filtered platelets (GFP) in the presence and absence of a typical nipecotamide (A-1C) were indicative of competitive inhibition (Ki = 19.28 microM). Scatchard analysis of 3H-PAF binding to GFP suggested the presence of high, intermediate (I) and low affinity binding sites, of which the I site gave a KD/app of 0.332 nM with an estimated 564 sites/platelet. Key interactions of nipecotamides with the PAF receptor appear to be the following (i) electrostatic interactions of the two amide oxygens with a primary set of electropositive areas spaced at 5-7 A, (ii) in the case of appropriate compounds, electrostatic interactions of the two amide oxygens spaced at 10-12 A with corresponding secondary receptor sites carrying positive electrostatic potential, (iii) a hydrophobic moiety fitting into a hydrophobic pocket in the receptor, and (iv) the cationic piperidine N+ (at pH 7.4) interacting with a counterion, probably aspartic acid.

A detailed structure-activity analysis was carried out using eight 1-alkyl(aralkyl)nipecotamides (type 5), 33 bis-nipecotamidoalkanes and aralkanes (type 6), and 7 N,N'-bis(nipecotoyl)-piperazines (type 7) as inhibitors of human platelet aggregation. Steric factors played an important role in determining the activity of type 5 compounds possessing an an appropriate degree of hydrophobic character. Types 6 and 7 compounds were more potent than the corresponding type 5 molecules. Hydrophobic character appeared to influence the activity of type 6 compounds. A 3-substituent on the piperidine ring was necessary for antiplatelet activity; the substituent should be preferably an amide with its C attached directly to the ring. 3,5-Disubstitution and 2-substitution led to a decline in activity. Optimal activity was attained when the two nipecotoyl ring N atoms were connected by an aralkyl group, and separated by approximately 7 A. It is suggested that van der Waals forces and pi interactions may govern the inhibitor-platelet interaction. The most potent type 6 inhibitor was alpha,alpha'-bis[3-(N-ethyl-N-butylcarbamoyl)piperidino]-p-xylene (6i). The most potent type 5 compound was 1-decyl-3-(N,N-diethylcarbamoyl)piperidine (5a). Any substitution on the piperazine ring of type 7 compounds led to a decline in activity, the most active analog being N,N'-bis(1-decylnipecotoyl)piperazine (7a). It is suggested that nipecotamides interact with anionic platelet sites located 7 A from each other and connected by a hydrophobic well.