473 matching studies

Sponsor Condition of Interest
Quantify the Degree of Pain Relief of Pelvic Congestion Syndrome Following Gonadal Vein Embolization
University of Kansas Medical Center Pelvic Congestive Syndrome Pelvic Pain
The primary objective is to quantify the degree of pain relief in patients undergoing gonadal vein embolization with coils as well as identify clinical or imaging factors that are predictive of a positive response to treatment, or poor response to treatment. expand

The primary objective is to quantify the degree of pain relief in patients undergoing gonadal vein embolization with coils as well as identify clinical or imaging factors that are predictive of a positive response to treatment, or poor response to treatment.

Type: Observational

Start Date: May 2019

open study

Sinus Disease in Young Children With Cystic Fibrosis
University of California, Los Angeles Cystic Fibrosis in Children Cystic Fibrosis Chronic Rhinosinusitis (Diagnosis) Olfactory Disorder Olfactory Impairment
This is a prospective, observational study examining the impact of highly effective cystic fibrosis transmembrane conductance regulator (CFTR) modulators on chronic rhinosinusitis (CRS) and olfactory dysfunction (OD) in young children with cystic fibrosis (YCwCF). This study involves two groups: children... expand

This is a prospective, observational study examining the impact of highly effective cystic fibrosis transmembrane conductance regulator (CFTR) modulators on chronic rhinosinusitis (CRS) and olfactory dysfunction (OD) in young children with cystic fibrosis (YCwCF). This study involves two groups: children 2-8 years old, inclusive at initial visit, receiving highly effective modulator therapy (HEMT), and a control group of children 2-8 years old, inclusive at initial visit, not receiving HEMT. Outcomes will include sinus magnetic resonance imaging (MRI) scans, olfactory tests, and quality of life surveys obtained over a two-year period.

Type: Observational

Start Date: Apr 2023

open study

A Study of Ficlatuzumab in Combination With Cetuximab in Participants With Recurrent or Metastatic (R/M)...
AVEO Pharmaceuticals, Inc. Metastatic Head-and-neck Squamous-cell Carcinoma Recurrent Head and Neck Squamous Cell Carcinoma
The purpose of this study is to compare the efficacy and safety of ficlatuzumab plus cetuximab compared to placebo plus cetuximab in participants with recurrent/metastatic (R/M) HPV-negative Head and Neck Cancer. The primary hypothesis is that ficlatuzumab combined with cetuximab is superior to cetuximab... expand

The purpose of this study is to compare the efficacy and safety of ficlatuzumab plus cetuximab compared to placebo plus cetuximab in participants with recurrent/metastatic (R/M) HPV-negative Head and Neck Cancer. The primary hypothesis is that ficlatuzumab combined with cetuximab is superior to cetuximab alone in terms of progression-free survival and/or overall survival.

Type: Interventional

Start Date: Jan 2024

open study

Study of PULSAR-ICI +/- IMSA101 in Patients With Oligometastatic NSCLC and RCC
ImmuneSensor Therapeutics Inc. Oligometastatic Disease
Phase 2, open-label, multicenter, randomized study comparing the safety and efficacy of personalized ultra-fractionated stereotactic adaptive radiotherapy (PULSAR) combined with immune checkpoint inhibitor (ICI) immunotherapy (PULSAR-ICI) + IMSA101 and PULSAR-ICI alone in patients with NSCLC or RCC expand

Phase 2, open-label, multicenter, randomized study comparing the safety and efficacy of personalized ultra-fractionated stereotactic adaptive radiotherapy (PULSAR) combined with immune checkpoint inhibitor (ICI) immunotherapy (PULSAR-ICI) + IMSA101 and PULSAR-ICI alone in patients with NSCLC or RCC

Type: Interventional

Start Date: Jun 2023

open study

Left Atrial Appendage Exclusion for Prophylactic Stroke Reduction Trial
AtriCure, Inc. Ischemic Stroke Systemic Embolism
This trial is a prospective, randomized, multicenter, multinational, blinded, superiority trial. The objective of this trial is to evaluate the effectiveness of left atrial appendage exclusion (LAAE) for the prevention of ischemic stroke or systemic arterial embolism in subjects undergoing cardiac... expand

This trial is a prospective, randomized, multicenter, multinational, blinded, superiority trial. The objective of this trial is to evaluate the effectiveness of left atrial appendage exclusion (LAAE) for the prevention of ischemic stroke or systemic arterial embolism in subjects undergoing cardiac surgery who have risk factors for atrial fibrillation and ischemic stroke.

Type: Interventional

Start Date: Jan 2023

open study

Phase I Trial to Evaluate VLP Peanut in Healthy and Peanut Allergic Subjects
Allergy Therapeutics Peanut Allergy
This phase I clinical trial is designed to evaluate the safety and tolerability of VLP Peanut in healthy subjects and in subjects with peanut allergy (PA). This clinical trial will evaluate the immunotoxicity profile of VLP Peanut in healthy subjects and assess the immunotoxicity profile and the degree... expand

This phase I clinical trial is designed to evaluate the safety and tolerability of VLP Peanut in healthy subjects and in subjects with peanut allergy (PA). This clinical trial will evaluate the immunotoxicity profile of VLP Peanut in healthy subjects and assess the immunotoxicity profile and the degree of reactogenicity (allergenicity) in subjects with PA. This clinical trial will also explore preliminary proof of efficacy of VLP Peanut in subjects with PA.

Type: Interventional

Start Date: Oct 2022

open study

Study of Sacituzumab Govitecan-hziy Versus Treatment of Physician's Choice in Patients With Previously...
Gilead Sciences Triple Negative Breast Cancer PD-L1 Negative
The primary objective of this study is to compare the progression-free survival (PFS) between sacituzumab govitecan-hziy (SG) versus treatment of physician's choice (TPC) in participants with previously untreated, locally advanced, inoperable or metastatic triple-negative breast cancer whose tumors... expand

The primary objective of this study is to compare the progression-free survival (PFS) between sacituzumab govitecan-hziy (SG) versus treatment of physician's choice (TPC) in participants with previously untreated, locally advanced, inoperable or metastatic triple-negative breast cancer whose tumors do not express programmed cell death ligand 1 (PD-L1) or in participants previously treated with anti-programmed cell death (ligand or protein) 1 (Anti-PD-(L)1) Agents in the early setting whose tumors do express PD-L1.

Type: Interventional

Start Date: Jul 2022

open study

A Study to Evaluate Safety, Efficacy of FF-10832 in Combo With Pembrolizumab in Urothelial & Non-small...
Fujifilm Pharmaceuticals U.S.A., Inc. Advanced Urothelial Carcinoma Advanced Non Small Cell Lung Cancer
To confirm a recommended Phase 2 dose (RP2D) of FF-10832 (Gemcitabine Liposome Injection) given intravenously Day 1 of a 21-day cycle, in combination with 200 mg pembrolizumab given intravenously Day 1 of the same 21-day cycle, for treatment of advanced urothelial and non-small cell lung cancer expand

To confirm a recommended Phase 2 dose (RP2D) of FF-10832 (Gemcitabine Liposome Injection) given intravenously Day 1 of a 21-day cycle, in combination with 200 mg pembrolizumab given intravenously Day 1 of the same 21-day cycle, for treatment of advanced urothelial and non-small cell lung cancer

Type: Interventional

Start Date: Jun 2022

open study

Phenotype, Genotype and Biomarkers 2
University of Miami Amyotrophic Lateral Sclerosis Hereditary Spastic Paraplegia Primary Lateral Sclerosis Progressive Muscular Atrophy Frontotemporal Dementia
The purpose of this study is to learn more about amyotrophic lateral sclerosis (ALS) and other related neurodegenerative diseases, including frontotemporal dementia (FTD), primary lateral sclerosis (PLS), hereditary spastic paraplegia (HSP), progressive muscular atrophy (PMA) and multisystem proteinopathy... expand

The purpose of this study is to learn more about amyotrophic lateral sclerosis (ALS) and other related neurodegenerative diseases, including frontotemporal dementia (FTD), primary lateral sclerosis (PLS), hereditary spastic paraplegia (HSP), progressive muscular atrophy (PMA) and multisystem proteinopathy (MSP). More precisely, the investigator wants to identify the links that exist between the disease phenotype (phenotype refers to observable signs and symptoms) and the disease genotype (genotype refers to your genetic information). The investigator also wants to identify biomarkers of ALS and related diseases.

Type: Observational

Start Date: Jan 2021

open study

Assessment of Safety and Effectiveness of NovoSorb® BTM in Severe Burns
PolyNovo Biomaterials Pty Ltd. Burns
This is a multi-center, pivotal study to assess the safety and effectiveness of a new method of treating severe burns using NovoSorb® Biodegradable Temporizing Matrix (BTM). expand

This is a multi-center, pivotal study to assess the safety and effectiveness of a new method of treating severe burns using NovoSorb® Biodegradable Temporizing Matrix (BTM).

Type: Interventional

Start Date: Sep 2021

open study

Surgery With or Without Neoadjuvant Chemotherapy in High Risk RetroPeritoneal Sarcoma
European Organisation for Research and Treatment of Cancer - EORTC Retroperitoneal Sarcoma Liposarcoma Leiomyosarcoma
This is a multicenter, randomized, open label phase lll trial to assess whether preoperative chemotherapy, as an adjunct to curative-intent surgery, improves the prognosis of high risk DDLPS (dedifferentiated Liposarcoma) and LMS (Leiomyosarcoma) patients as measured by disease free survival. After... expand

This is a multicenter, randomized, open label phase lll trial to assess whether preoperative chemotherapy, as an adjunct to curative-intent surgery, improves the prognosis of high risk DDLPS (dedifferentiated Liposarcoma) and LMS (Leiomyosarcoma) patients as measured by disease free survival. After confirmation of eligibility criteria, patients will be randomized to either the standard arm or experimental arm.

Type: Interventional

Start Date: Jan 2021

open study

Testing the Safety of Adding Either Monalizumab (IPH2201) or Oleclumab (MEDI9447) to Durvalumab (MEDI4736)...
National Cancer Institute (NCI) Locally Advanced Lung Non-Small Cell Carcinoma Locally Recurrent Lung Non-Small Cell Carcinoma Stage II Lung Cancer AJCC v8 Stage III Lung Cancer AJCC v8 Unresectable Lung Non-Small Cell Carcinoma
This phase I trial studies the safety of adding durvalumab to accelerated hypofractionated radiation therapy (ACRT) or conventionally fractionated radiation therapy, as well as the safety of adding either monalizumab or oleclumab to durvalumab plus conventionally fractionated radiation therapy in... expand

This phase I trial studies the safety of adding durvalumab to accelerated hypofractionated radiation therapy (ACRT) or conventionally fractionated radiation therapy, as well as the safety of adding either monalizumab or oleclumab to durvalumab plus conventionally fractionated radiation therapy in treating patients with non-small cell lung cancer that has spread to nearby tissue or lymph nodes (locally advanced). Accelerated hypofractionated radiation therapy delivers higher doses of radiation therapy over a shorter period of time and may kill more tumor cells and have fewer side effects. Immunotherapy with monoclonal antibodies, such as durvalumab and monalizumab, may help the body's immune system attack the tumor, and may interfere with the ability of tumor cells to grow and spread. Oleclumab is in a class of medications called monoclonal antibodies. It binds to a protein called CD73, which is found on some types of tumor cells. Oleclumab may block CD73 and help the immune system kill tumor cells. It is not yet known whether adding durvalumab to ACRT or adding monalizumab or oleclumab to durvalumab plus conventionally fractionated radiation therapy will work better in treating patients with non-small cell lung cancer.

Type: Interventional

Start Date: Oct 2019

open study

Idiopathic Pulmonary Fibrosis and Interstitial Lung Disease Prospective Outcomes Registry
Duke University Idiopathic Pulmonary Fibrosis, Interstitial Lung Disease
The Idiopathic Pulmonary Fibrosis Prospective Outcomes (IPF-PRO) Registry started recruiting in 2014 with the objective of studying Idiopathic Pulmonary Fibrosis. In 2018, the registry expanded to include recruitment of participants with other chronic fibrosing interstitial lung diseases (ILDs) with... expand

The Idiopathic Pulmonary Fibrosis Prospective Outcomes (IPF-PRO) Registry started recruiting in 2014 with the objective of studying Idiopathic Pulmonary Fibrosis. In 2018, the registry expanded to include recruitment of participants with other chronic fibrosing interstitial lung diseases (ILDs) with progressive phenotype also referred to as progressive fibrosing interstitial lung diseases in the Chronic Fibrosis Interstitial Lung Disease with Progressive Phenotype (ILD-PRO) Registry. When the third phase of the registry begins, the IPF-PRO registry will enroll additional patients with idiopathic pulmonary fibrosis. This IPF-PRO registry is a prospective registry that will collect information regarding the natural history, health care interactions, participant reported questionnaire data to assess quality of life, and the methods of treatment of participants with a diagnosis of idiopathic pulmonary fibrosis (IPF) or of another chronic fibrosing interstitial lung disease (ILD) with progressive phenotype established at the enrolling centers. In addition, blood samples and chest image studies will be collected and banked for future research projects.

Type: Observational [Patient Registry]

Start Date: Jun 2014

open study

Phosphatase Inhibition by Intracoronary Gene Therapy in Subjects With Non-Ischemic NYHA Class III Heart...
Asklepios Biopharmaceutical, Inc. Congestive Heart Failure
This is a Phase 2 adaptive, double-blinded, placebo-controlled, randomized, multi-center trial study to evaluate the safety and efficacy of a single dose of AB-1002, administered via antegrade intracoronary artery infusion, in males and females age >18 years with non-ischemic cardiomyopathy and NYHA... expand

This is a Phase 2 adaptive, double-blinded, placebo-controlled, randomized, multi-center trial study to evaluate the safety and efficacy of a single dose of AB-1002, administered via antegrade intracoronary artery infusion, in males and females age >18 years with non-ischemic cardiomyopathy and NYHA Class III symptoms of HF. Subjects will be randomized into one of three treatment groups in a 1:1:1

Type: Interventional

Start Date: Oct 2023

open study

Effects of Metformin on Airway Ion Channel Dysfunction in Cystic Fibrosis-related Diabetes
University of Kansas Medical Center Cystic Fibrosis-related Diabetes Cystic Fibrosis
The purpose of this study is to assess the efficacy of metformin to improve airway ion channel function in those with CF-related diabetes (CFRD) expand

The purpose of this study is to assess the efficacy of metformin to improve airway ion channel function in those with CF-related diabetes (CFRD)

Type: Interventional

Start Date: Feb 2022

open study

Testing the Addition of a New Anti-cancer Drug, Radium-223 Dichloride, to the Usual Treatment (Cabozantinib)...
National Cancer Institute (NCI) Advanced Renal Cell Carcinoma Chromophobe Renal Cell Carcinoma Clear Cell Renal Cell Carcinoma Collecting Duct Carcinoma Kidney Medullary Carcinoma
This phase II trial studies whether adding radium-223 dichloride to the usual treatment, cabozantinib, improves outcomes in patients with renal cell cancer that has spread to the bone. Radioactive drugs such as radium-223 dichloride may directly target radiation to cancer cells and minimize harm to... expand

This phase II trial studies whether adding radium-223 dichloride to the usual treatment, cabozantinib, improves outcomes in patients with renal cell cancer that has spread to the bone. Radioactive drugs such as radium-223 dichloride may directly target radiation to cancer cells and minimize harm to normal cells. Cabozantinib may stop the growth of cancer cells by blocking some of the enzymes needed for cell growth. Giving radium-223 dichloride and cabozantinib may help lessen the pain and symptoms from renal cell cancer that has spread to the bone, compared to cabozantinib alone.

Type: Interventional

Start Date: Jul 2020

open study

Phase I/II Study of Rapcabtagene Autoleucel in CLL, 3L+ DLBCL, ALL and 1L HR LBCL
Novartis Pharmaceuticals Chronic Lymphocytic Leukemia Small Lymphocytic Lymphoma Diffuse Large B-cell Lymphoma Acute Lymphoblastic Leukemia Large B-cell Lymphoma
This is a phase I/II study to evaluate the feasibility, safety and preliminary antitumor efficacy of rapcabtagene autoleucel (also known as YTB323). Rapcabtagene autoleucel will be investigated in combination with ibrutinib in chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) and... expand

This is a phase I/II study to evaluate the feasibility, safety and preliminary antitumor efficacy of rapcabtagene autoleucel (also known as YTB323). Rapcabtagene autoleucel will be investigated in combination with ibrutinib in chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) and as single agent in diffuse large B-cell lymphoma (3L+ DLBCL), adult acute lymphoblastic leukemia (ALL) and 1st Line High Risk Large B-Cell Lymphoma (1L HR LBCL).

Type: Interventional

Start Date: Jun 2019

open study

Crizotinib in Treating Patients With Stage IB-IIIA Non-small Cell Lung Cancer That Has Been Removed by...
ECOG-ACRIN Cancer Research Group ALK Gene Rearrangement ALK Gene Translocation ALK Positive Stage IB Non-Small Cell Lung Carcinoma AJCC v7 Stage II Non-Small Cell Lung Cancer AJCC v7
This randomized phase III trial studies how well crizotinib works in treating patients with stage IB-IIIA non-small cell lung cancer that has been removed by surgery and has a mutation in a protein called anaplastic lymphoma kinase (ALK). Mutations, or changes, in ALK can make it very active and important... expand

This randomized phase III trial studies how well crizotinib works in treating patients with stage IB-IIIA non-small cell lung cancer that has been removed by surgery and has a mutation in a protein called anaplastic lymphoma kinase (ALK). Mutations, or changes, in ALK can make it very active and important for tumor cell growth and progression. Crizotinib may stop the growth of tumor cells by blocking the ALK protein from working. Crizotinib may be an effective treatment for patients with non-small cell lung cancer and an ALK fusion mutation.

Type: Interventional

Start Date: Mar 2015

open study

HF2 Registry - Hemodynamic Frontiers in Heart Failure Registry
University of Kansas Medical Center Heart Failure
The purpose of the HF2 (Hemodynamic Frontiers in Heart Failure) registry is to collect relevant patient-level demographic, clinical, laboratory, and hemodynamic data from patients implanted with pulmonary artery pressure sensor at participating centers to advance scientific knowledge about ambulatory... expand

The purpose of the HF2 (Hemodynamic Frontiers in Heart Failure) registry is to collect relevant patient-level demographic, clinical, laboratory, and hemodynamic data from patients implanted with pulmonary artery pressure sensor at participating centers to advance scientific knowledge about ambulatory hemodynamics monitoring and HF (Heart Failure) therapies. The data collected will be used for retrospective studies, quality improvement, identifying research cohorts, and member-initiated research.

Type: Observational [Patient Registry]

Start Date: Oct 2022

open study

Safety and Effectiveness of the Genio® bilAteral Stimulation for Treatment of Complete Concentric CollapsE...
Nyxoah S.A. Sleep Apnea, Obstructive
The solution offered by the Genio System to treat OSA patients with CCC using bilateral HGNS has a favorable risk-benefit ratio, as demonstrated by evidence from 2 studies. expand

The solution offered by the Genio System to treat OSA patients with CCC using bilateral HGNS has a favorable risk-benefit ratio, as demonstrated by evidence from 2 studies.

Type: Interventional

Start Date: Dec 2022

open study

Colorectal Cancer Screening in Cystic Fibrosis
University of Washington, the Collaborative Health Studies Coordinating Center Cystic Fibrosis Colorectal Cancer Adenoma
This multi-center study will compare multi-target DNA and quantitative FIT stool-based testing to colonoscopy in individuals with Cystic Fibrosis (CF) undergoing colon cancer screening with colonoscopy. The primary endpoint is detection of any adenomas, including advanced adenomas and colorectal cancer... expand

This multi-center study will compare multi-target DNA and quantitative FIT stool-based testing to colonoscopy in individuals with Cystic Fibrosis (CF) undergoing colon cancer screening with colonoscopy. The primary endpoint is detection of any adenomas, including advanced adenomas and colorectal cancer (CRC).

Type: Observational

Start Date: Sep 2022

open study

GammaTile and Stupp in Newly Diagnosed GBM
GT Medical Technologies, Inc. Glioblastoma
In summary, standard of care postoperative chemoradiation for patients with newly diagnosed GBM does not routinely provide durable local control or prolonged overall survival. As discussed above it seems unlikely that patient outcomes will be significantly improved with radiation dose escalation given... expand

In summary, standard of care postoperative chemoradiation for patients with newly diagnosed GBM does not routinely provide durable local control or prolonged overall survival. As discussed above it seems unlikely that patient outcomes will be significantly improved with radiation dose escalation given at the time of the EBRT boost. However, as most failures are local, improving LC could potentially improve the OS of patients. To do this, we propose a shift in the traditional radiation paradigm. This study will assess the feasibility and tolerability of adding GT radiation therapy as an upfront boost at the time of maximum safe resection, along with the backbone of the current standard of care approach, concomitant and adjuvant temozolomide +/- TTF, for patients with newly diagnosed GBM. GT, a novel brain brachytherapy device utilizing Cs-131 embedded in bioresorbable collagen tiles, offers a more sophisticated carrier and a shorter half-life radioisotope, Cs-131. Use of this device allows for radiation initiation at an earlier time point and a more rapid dose delivery and possibly more effective tumor control particularly for rapidly proliferating tumors such as GBM. Two prospective studies have demonstrated the safety and efficacy of re-irradiation with GT in patients with recurrent GBM. The overarching goal of this single-arm, open label phase 4 study is to determine the feasibility and tolerability of treating patients with GammaTile in combination with the Stupp Protocol and how to proceed with testing this treatment in a future, larger, randomized clinical study. The aims of the study are to demonstrate that the use of GammaTile at the time of surgery is well tolerated and does not delay the start of the Stupp protocol. Efficacy outcomes (e.g., LC, OS, PFS) will also be described.

Type: Interventional

Start Date: Aug 2022

open study

Autologous Muscle Derived Cells Compared to Placebo for Urinary Sphincter Repair in Post-surgical Female...
Cook MyoSite Stress Urinary Incontinence
This study evaluates the efficacy and safety of Autologous Muscle Derived Cells for Urinary Sphincter Repair (AMDC-USR; generic name: iltamiocel) compared to a placebo in the reduction of stress incontinence episode frequency in adult female patients with post-surgical persistent or recurrent stress... expand

This study evaluates the efficacy and safety of Autologous Muscle Derived Cells for Urinary Sphincter Repair (AMDC-USR; generic name: iltamiocel) compared to a placebo in the reduction of stress incontinence episode frequency in adult female patients with post-surgical persistent or recurrent stress urinary incontinence (SUI). Half of the participants will receive AMDC-USR (injections with cells) and the other half will receive placebo.

Type: Interventional

Start Date: Apr 2019

open study

Registry Study for Radiation Therapy Outcomes
Proton Collaborative Group Neoplasms
The purpose of this research study is to collect and analyze information from patients being treated with various forms of radiation therapy. expand

The purpose of this research study is to collect and analyze information from patients being treated with various forms of radiation therapy.

Type: Observational [Patient Registry]

Start Date: Jun 2009

open study

Nephrotic Syndrome Study Network
University of Michigan Minimal Change Disease (MCD) Membranous Nephropathy Glomerulosclerosis, Focal Segmental
Minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), and Membranous nephropathy (MN), generate an enormous individual and societal financial burden, accounting for approximately 12% of prevalent end stage renal disease (ESRD) cases (2005) at an annual cost in the US of more than... expand

Minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), and Membranous nephropathy (MN), generate an enormous individual and societal financial burden, accounting for approximately 12% of prevalent end stage renal disease (ESRD) cases (2005) at an annual cost in the US of more than $3 billion. However, the clinical classification of these diseases is widely believed to be inadequate by the scientific community. Given the poor understanding of MCD/FSGS and MN biology, it is not surprising that the available therapies are imperfect. The therapies lack a clear biological basis, and as many families have experienced, they are often not beneficial, and in fact may be significantly toxic. Given these observations, it is essential that research be conducted that address these serious obstacles to effectively caring for patients. In response to a request for applications by the National Institutes of Health, Office of Rare Diseases (NIH, ORD) for the creation of Rare Disease Clinical Research Consortia, a number of affiliated universities joined together with The NephCure Foundation the NIDDK, the ORDR, and the University of Michigan in collaboration towards the establishment of a Nephrotic Syndrome (NS) Rare Diseases Clinical Research Consortium. Through this consortium the investigators hope to understand the fundamental biology of these rare diseases and aim to bank long-term observational data and corresponding biological specimens for researchers to access and further enrich.

Type: Observational

Start Date: Apr 2010

open study