Study protocol: A randomized, double-blind, placebo-controlled trial of isavuconazole prophylaxis for the prevention of covid-19-associated pulmonary aspergillosis.

Background: During the early stages of the coronavirus disease 2019 (COVID-19) pandemic, those with severe COVID-19 infection were at risk for a number of opportunistic infections including COVID-19-associated pulmonary aspergillosis (CAPA). We initiated a randomized clinical trial to evaluate whether isavuconazole, a triazole antifungal, could prevent CAPA and improve survival in patients admitted to the ICU with severe COVID-19 infection. Methods: We designed a phase III/IV randomized, double-blind, two-arm, placebo-controlled trial evaluating standard of care (SOC) plus isavuconazole versus SOC plus placebo and were to enroll participants admitted to the ICU with severe COVID-19 infection at three medical centers in California, United States. The projected sample size was 162 participants. Results: Due to poor enrollment and the declining number of COVID-19 cases over time, the study was terminated after 7 participants were enrolled, all enrolled at one study site (UC San Diego Health). CAPA was suspected in two participants and they were started on open-label isavuconazole. One was withdrawn due to possible isavuconazole-related adverse side effects. Conclusion: Enrollment was slower-than-expected due to multiple factors, including competing COVID-19-related studies and hesitancy from potential study participants or their families to join the study. Our experience highlights some of the difficulties in planning and running a clinical trial focused on fungal superinfections involving severely ill patients during the height of the COVID-19 pandemic. Lessons learned from this study will help in the design of proposed studies examining antifungal prophylaxis against aspergillosis following other severe respiratory viral infections.

Universal digital high-resolution melting for the detection of pulmonary mold infections.

Invasive mold infections (IMIs) are associated with high morbidity, particularly in immunocompromised patients, with mortality rates between 40% and 80%. Early initiation of appropriate antifungal therapy can substantially improve outcomes, yet early diagnosis remains difficult to establish and often requires multidisciplinary teams evaluating clinical and radiological findings plus supportive mycological findings. Universal digital high-resolution melting (U-dHRM) analysis may enable rapid and robust diagnoses of IMI. A universal fungal assay was developed for U-dHRM and used to generate a database of melt curve signatures for 19 clinically relevant fungal pathogens. A machine learning algorithm (ML) was trained to automatically classify these pathogen curves and detect novel melt curves. Performance was assessed on 73 clinical bronchoalveolar lavage samples from patients suspected of IMI. Novel curves were identified by micropipetting U-dHRM reactions and Sanger sequencing amplicons. U-dHRM achieved 97% overall fungal organism identification accuracy and a turnaround time of ~4 hrs. U-dHRM detected pathogenic molds (Aspergillus, Mucorales, Lomentospora, and Fusarium) in 73% of 30 samples classified as IMI, including mixed infections. Specificity was optimized by requiring the number of pathogenic mold curves detected in a sample to be >8 and a sample volume to be 1 mL, which resulted in 100% specificity in 21 at-risk patients without IMI. U-dHRM showed promise as a separate or combination diagnostic approach to standard mycological tests. U-dHRM's speed, ability to simultaneously identify and quantify clinically relevant mold pathogens in polymicrobial samples, and detect emerging opportunistic pathogens may aid treatment decisions, improving patient outcomes. IMPORTANCE: Improvements in diagnostics for invasive mold infections are urgently needed. This work presents a new molecular detection approach that addresses technical and workflow challenges to provide fast pathogen detection, identification, and quantification that could inform treatment to improve patient outcomes.

Novel antifungals and treatment approaches to tackle resistance and improve outcomes of invasive fungal disease.

SUMMARYFungal infections are on the rise, driven by a growing population at risk and climate change. Currently available antifungals include only five classes, and their utility and efficacy in antifungal treatment are limited by one or more of innate or acquired resistance in some fungi, poor penetration into "sequestered" sites, and agent-specific side effect which require frequent patient reassessment and monitoring. Agents with novel mechanisms, favorable pharmacokinetic (PK) profiles including good oral bioavailability, and fungicidal mechanism(s) are urgently needed. Here, we provide a comprehensive review of novel antifungal agents, with both improved known mechanisms of actions and new antifungal classes, currently in clinical development for treating invasive yeast, mold (filamentous fungi), Pneumocystis jirovecii infections, and dimorphic fungi (endemic mycoses). We further focus on inhaled antifungals and the role of immunotherapy in tackling fungal infections, and the specific PK/pharmacodynamic profiles, tissue distributions as well as drug-drug interactions of novel antifungals. Finally, we review antifungal resistance mechanisms, the role of use of antifungal pesticides in agriculture as drivers of drug resistance, and detail detection methods for antifungal resistance.

Impact of climate change and natural disasters on fungal infections.

The effects of climate change and natural disasters on fungal pathogens and the risks for fungal diseases remain incompletely understood. In this literature review, we examined how fungi are adapting to an increase in the Earth's temperature and are becoming more thermotolerant, which is enhancing fungal fitness and virulence. Climate change is creating conditions conducive to the emergence of new fungal pathogens and is priming fungi to adapt to previously inhospitable environments, such as polluted habitats and urban areas, leading to the geographical spread of some fungi to traditionally non-endemic areas. Climate change is also contributing to increases in the frequency and severity of natural disasters, which can trigger outbreaks of fungal diseases and increase the spread of fungal pathogens. The populations mostly affected are the socially vulnerable. More awareness, research, funding, and policies on the part of key stakeholders are needed to mitigate the effects of climate change and disaster-related fungal diseases.

Trichomoniasis and retesting in Durham County, North Carolina, United States, 2021 - 2022.

BACKGROUND: The Centers for Disease Control and Prevention recommends universal retesting within 3 months after treatment of Trichomonas vaginalis infection given high rates of persistent infection or reinfection, or if this is not possible, within 12 months following treatment. Data is lacking on how often this is actually done. METHODS: We analyzed the demographic and clinical characteristics, rate of return for the recommended retesting, concordance between wet prep and nucleic acid amplification testing, and percent positivity for T. vaginalis on repeat vaginal specimens at a local public health department in Durham, North Carolina, United States. RESULTS: Of 193 females treated for trichomoniasis between March 1, 2021 - May 31, 2022, 83% were Black or African American and 44% between the ages of 20 and 29 years. Of these individuals, 32% had retesting performed within 3 months and 50% within 365 days after treatment. Females between the ages of 20 and 29 years were more likely to return for retesting than those between the ages of 30 and 39 years. Of those who returned for retesting, 10% were positive on repeat testing. CONCLUSION: In this study, 50% of females diagnosed with trichomoniasis completed retesting within 365 days. Improved scheduling of clients at the time of trichomoniasis treatment and improved identification in our electronic health record of individuals diagnosed with trichomoniasis within the prior year would likely improve retesting rates. Given the high prevalence of trichomoniasis, expanded screening of asymptomatic females in settings where this is feasible may be warranted.

Combating COVID-19 Vaccine Inequity During the Early Stages of the COVID-19 Pandemic.

Throughout the COVID-19 pandemic, populations of color have been disproportionately impacted, with higher rates of infection, hospitalization, and mortality, compared to non-Hispanic whites. These disparities in health outcomes are likely related to a combination of factors including underlying socioeconomic inequities, unequal access to healthcare, higher rates of employment in essential or public-facing occupations, language barriers, and COVID-19 vaccine inequities. In this manuscript the authors discuss strategies of how one local health department responded to vaccine inequities to better serve historically excluded communities throughout the early stages of the COVID-19 pandemic in 2021. These efforts helped increase vaccination rates in marginalized communities, primarily in the Black or African American population in Durham County, North Carolina.

Social determinants of health as drivers of fungal disease.

Disparities in social determinants of health (SDOH) play a significant role in causing health inequities globally. The physical environment, including housing and workplace environment, can increase the prevalence and spread of fungal infections. A number of professions are associated with increased fungal infection risk and are associated with low pay, which may be linked to crowded and sub-optimal living conditions, exposure to fungal organisms, lack of access to quality health care, and risk for fungal infection. Those involved and displaced from areas of armed conflict have an increased risk of invasive fungal infections. Lastly, a number of fungal plant pathogens already threaten food security, which will become more problematic with global climate change. Taken together, disparities in SDOH are associated with increased risk for contracting fungal infections. More emphasis needs to be placed on systematic approaches to better understand the impact and reducing the health inequities associated with these disparities.

Universal Digital High Resolution Melt for the detection of pulmonary mold infections.

Background: Invasive mold infections (IMIs) such as aspergillosis, mucormycosis, fusariosis, and lomentosporiosis are associated with high morbidity and mortality, particularly in immunocompromised patients, with mortality rates as high as 40% to 80%. Outcomes could be substantially improved with early initiation of appropriate antifungal therapy, yet early diagnosis remains difficult to establish and often requires multidisciplinary teams evaluating clinical and radiological findings plus supportive mycological findings. Universal digital high resolution melting analysis (U-dHRM) may enable rapid and robust diagnosis of IMI. This technology aims to accomplish timely pathogen detection at the single genome level by conducting broad-based amplification of microbial barcoding genes in a digital polymerase chain reaction (dPCR) format, followed by high-resolution melting of the DNA amplicons in each digital reaction to generate organism-specific melt curve signatures that are identified by machine learning. Methods: A universal fungal assay was developed for U-dHRM and used to generate a database of melt curve signatures for 19 clinically relevant fungal pathogens. A machine learning algorithm (ML) was trained to automatically classify these 19 fungal melt curves and detect novel melt curves. Performance was assessed on 73 clinical bronchoalveolar lavage (BAL) samples from patients suspected of IMI. Novel curves were identified by micropipetting U-dHRM reactions and Sanger sequencing amplicons. Results: U-dHRM achieved an average of 97% fungal organism identification accuracy and a turn-around-time of 4hrs. Pathogenic molds (Aspergillus, Mucorales, Lomentospora and Fusarium) were detected by U-dHRM in 73% of BALF samples suspected of IMI. Mixtures of pathogenic molds were detected in 19%. U-dHRM demonstrated good sensitivity for IMI, as defined by current diagnostic criteria, when clinical findings were also considered. Conclusions: U-dHRM showed promising performance as a separate or combination diagnostic approach to standard mycological tests. The speed of U-dHRM and its ability to simultaneously identify and quantify clinically relevant mold pathogens in polymicrobial samples as well as detect emerging opportunistic pathogens may provide information that could aid in treatment decisions and improve patient outcomes.

Mpox Vaccination and the Role of Social Vulnerability in Durham County, North Carolina, USA.

BACKGROUND: Disparities in vaccine coverage among groups in the USA is common, possibly due to higher vaccine hesitancy in certain populations, difficulty accessing vaccines, and underlying social vulnerability. METHODS: The aim of this study was to investigate the association between mpox vaccine administration, social determinants of health, and social vulnerability index (SVI) in Durham County, North Carolina, USA. Random forest regression (RFE) and min-max scaling preprocessing were used to predict mpox vaccinations in Durham County at the census tract level. The top eleven most influential features and their correlations with mpox vaccination were calculated. RESULTS: Non-Hispanic white individuals, males, and those between the ages of 20 and 40 years were overrepresented in mpox vaccine reception in Durham County. Surprisingly, lacking a high school diploma, lacking health insurance, lacking a household vehicle, and living below the poverty line were all positively associated with receiving the mpox vaccine. Being a Black or African American and Hispanic or Latino individual was also positively associated with receiving the mpox vaccine. DISCUSSION: Vaccine outreach efforts in Durham County, North Carolina, had success in reaching at-risk individuals, including socially vulnerable individuals. Future research should focus more specifically on how social vulnerability relates to vaccine reception for vaccine-preventable diseases.

An update on current and novel molecular diagnostics for the diagnosis of invasive fungal infections.

BACKGROUND: Invasive fungal infections cause millions of infections annually, but diagnosis remains challenging. There is an increased need for low-cost, easy to use, highly sensitive and specific molecular assays that can differentiate between colonized and pathogenic organisms from different clinical specimens. AREAS COVERED: We reviewed the literature evaluating the current state of molecular diagnostics for invasive fungal infections, focusing on current and novel molecular tests such as polymerase chain reaction (PCR), digital PCR, high-resolution melt (HRM), and metagenomics/next generation sequencing (mNGS). EXPERT OPINION: PCR is highly sensitive and specific, although performance can be impacted by prior/concurrent antifungal use. PCR assays can identify mutations associated with antifungal resistance, non-Aspergillus mold infections, and infections from endemic fungi. HRM is a rapid and highly sensitive diagnostic modality that can identify a wide range of fungal pathogens, including down to the species level, but multiplex assays are limited and HRM is currently unavailable in most healthcare settings, although universal HRM is working to overcome this limitation. mNGS offers a promising approach for rapid and hypothesis-free diagnosis of a wide range of fungal pathogens, although some drawbacks include limited access, variable performance across platforms, the expertise and costs associated with this method, and long turnaround times in real-world settings.

Treatment of Fusarium Infection of the Central Nervous System: A Review of Past Cases to Guide Therapy for the Ongoing 2023 Outbreak in the United States and Mexico.

INTRODUCTION: Fusariosis of the central nervous system (CNS) is extremely uncommon. Treatment and outcome data from previously published cases may provide some guidance in light of the ongoing fungal meningitis outbreak in 2023 involving Fusarium spp. in the United States and Mexico. METHODS: We reviewed the published literature describing cases of invasive fusariosis of the (CNS) that included data on patient demographic characteristics, treatment, and outcome. RESULTS: Twenty-six cases met inclusion criteria. The mean age was 36 years, 55% involved females, 60% had underlying hematologic malignancy, and another 16% were on immunosuppressants. The majority of infections were from Fusarium solani species complex. Overall 72% of patients died. The majority received monotherapy with amphotericin B, although some received voriconazole monotherapy or combination therapy with amphotericin B plus voriconazole with or without adjuvant surgery. Among the survivors, 3 received amphotericin B monotherapy, 2 voriconazole monotherapy, 1 combination therapy of both, and one surgery only. CONCLUSION: The overall mortality rate in published cases of fusariosis of the CNS was high, although-unlike during the current outbreak-the preponderance of patients were severely immunocompromised. While historically the majority were treated with amphotericin B monotherapy, some recent patients were treated with voriconazole monotherapy or combination therapy with amphotericin B plus voriconazole. Current guidelines recommend monotherapy with voriconazole or lipid formulations of amphotericin B or combination of both for the treatment of invasive fusariosis, which is in line with the findings from our literature review and should be considered during the ongoing 2023 outbreak.

Fungal Endocarditis: Pathophysiology, Epidemiology, Clinical Presentation, Diagnosis, and Management.

Fungal endocarditis accounts for 1% to 3% of all infective endocarditis cases, is associated with high morbidity and mortality (>70%), and presents numerous challenges during clinical care. Candida spp. are the most common causes of fungal endocarditis, implicated in over 50% of cases, followed by Aspergillus and Histoplasma spp. Important risk factors for fungal endocarditis include prosthetic valves, prior heart surgery, and injection drug use. The signs and symptoms of fungal endocarditis are nonspecific, and a high degree of clinical suspicion coupled with the judicious use of diagnostic tests is required for diagnosis. In addition to microbiological diagnostics (e.g., blood culture for Candida spp. or galactomannan testing and PCR for Aspergillus spp.), echocardiography remains critical for evaluation of potential infective endocarditis, although radionuclide imaging modalities such as 18F-fluorodeoxyglucose positron emission tomography/computed tomography are increasingly being used. A multimodal treatment approach is necessary: surgery is usually required and should be accompanied by long-term systemic antifungal therapy, such as echinocandin therapy for Candida endocarditis or voriconazole therapy for Aspergillus endocarditis.

Relationship Between Sexually Transmitted Infections and Social Determinants of Health in Durham County, North Carolina, United States.

Background: Sexually transmitted infections (STIs) are increasing in the United States, and certain populations are more at risk than others. One explanation for this is inequities in underlying social determinants of health (SDOH). Methods: We analyzed chlamydia, gonorrhea, and syphilis cases in Durham County, North Carolina, from 01/01/2020 to 12/31/2020 by select SDOH at the census tract level. We included 48 variables of interest, including variables related to income, education, transportation, and health insurance. For each variable, we modeled STI incidence at the census tract level using Poisson regression. Wald's chi-square was used to determine which variables were significantly associated with STI incidence. Results: Of 24 variables that were statistically associated with STI incidence at the census tract level, 9 were negatively associated and 15 positively associated with STI incidence. Having employer health insurance was most strongly associated with lower-than-expected STI incidence, and having Medicaid insurance, no health insurance, using public transportation, and income below the poverty level were most strongly associated with higher-than-expected STI incidence. Lastly, STI incidence was not associated with race or ethnicity overall across Durham County, except in historically marginalized areas, where we found higher-than-expected STI incidence. Conclusions: We found that lacking health insurance, having Medicaid insurance, using public transportation, and income below the poverty level were most strongly associated with higher-than-expected STI incidence. Strategies to combat increasing STIs may include improving access to health insurance, reducing barriers to cost-effective and timely transportation to medical appointments, and raising wages to bring individuals out of poverty.

Race and ethnicity: Risk factors for fungal infections?

Racial and ethnic identities, largely understood as social rather than biologic constructs, may impact risk for acquiring infectious diseases, including fungal infections. Risk factors may include genetic and immunologic differences such as aberrations in host immune response, host polymorphisms, and epigenomic factors stemming from environmental exposures and underlying social determinants of health. In addition, certain racial and ethnic groups may be predisposed to diseases that increase risk for fungal infections, as well as disparities in healthcare access and health insurance. In this review, we analyzed racial and ethnic identities as risk factors for acquiring fungal infections, as well as race and ethnicity as they relate to risk for severe disease from fungal infections. Risk factors for invasive mold infections such as aspergillosis largely appear related to environmental differences and underlying social determinants of health, although immunologic aberrations and genetic polymorphisms may contribute in some circumstances. Although black and African American individuals appear to be at high risk for superficial and invasive Candida infections and cryptococcosis, the reasons for this are unclear and may be related to underling social determinants of health, disparities in access to healthcare, and other socioeconomic disparities. Risk factors for all the endemic fungi are likely largely related to underlying social determinants of health, socioeconomic, and health disparities, although immunologic mechanisms likely play a role as well, particularly in disseminated coccidioidomycosis.

Test-of-Cure After Treatment of Pharyngeal Gonorrhea in Durham, North Carolina, 2021-2022.

BACKGROUND: In December 2020, the Centers for Disease Control and Prevention updated its treatment guidelines for gonococcal infection and, for the first time, recommended universal test-of-cure for all individuals treated for pharyngeal gonorrhea. After the release of these guidelines, data are lacking on rates of return for the test-of-cure, particularly in populations other than men who have sex with men. METHODS: We analyzed the demographic characteristics, clinical characteristics, rate of return for the recommended test-of-cure, and percent positivity for Neisseria gonorrhoeae on repeat pharyngeal specimens at a local public health department in Durham, NC. RESULTS: Of 101 individuals treated for pharyngeal gonorrhea between March 2021 and April 2022, 54.5% were men, 71.2% Black or African American, and 58.4% between the ages of 20 and 29 years. Most identified as either women who have sex with men (38.6%), men who have sex with men (24.8%), or men who have sex with women (22.8%). Of these individuals, 41 (40.6%) returned for a test-of-cure, with LGBTQ+ individuals more likely to return than men who have sex with women and women who have sex with men. Of those who returned for the test-of-cure, 4.9% of pharyngeal samples were equivocal and 2.4% positive for N. gonorrhoeae by nucleic acid amplification testing, likely reflecting false-positive tests. CONCLUSION: Despite recommendations to perform a test-of-cure 7 to 14 days after treatment of pharyngeal gonorrhea, rates of return continue to be low. Alternative strategies should be investigated to increase test-of-cure rates.

Antimicrobial-Resistant Shigella spp. in San Diego, California, USA, 2017-2020.

Annually, Shigella spp. cause ≈188 million cases of diarrheal disease globally, including 500,000 cases in the United States; rates of antimicrobial resistance are increasing. To determine antimicrobial resistance and risk factors in San Diego, California, USA, we retrospectively reviewed cases of diarrheal disease caused by Shigella flexneri and S. sonnei diagnosed during 2017-2020. Of 128 evaluable cases, S. flexneri was slightly more common than S. sonnei; most cases were in persons who were gay or bisexual cisgender men, were living with HIV, were unhoused, or used methamphetamines. Overall, rates of resistance to azithromycin, fluoroquinolones, ampicillin, and trimethoprim/sulfamethoxazole (TMP/SMX) were comparable to the most recent national data reported from the Centers for Disease Control and Prevention; 55% of isolates were resistant to azithromycin, 23% to fluoroquinolones, 70% to ampicillin, and 83% to TMP/SMX. The rates that we found for TMP/SMX were slightly higher than those in national data.

Let's talk about sex characteristics-As a risk factor for invasive fungal diseases.

Biological sex, which comprises differences in host sex hormone homeostasis and immune responses, can have a substantial impact on the epidemiology of infectious diseases. Comprehensive data on sex distributions in invasive fungal diseases (IFDs) are lacking. In this review, we performed a literature search of in vitro/animal studies, clinical studies, systematic reviews and meta-analyses of invasive fungal infections. Females represented 51.2% of invasive candidiasis cases, mostly matching the proportions of females among the general population in the United States and Europe (>51%). In contrast, other IFDs were overrepresented in males, including invasive aspergillosis (51% males), mucormycosis (60%), cryptococcosis (74%), coccidioidomycosis (70%), histoplasmosis (61%) and blastomycosis (66%). Behavioural variations, as well as differences related to biological sex, may only in part explain these findings. Further investigations concerning the association between biological sex/gender and the pathogenesis of IFDs are warranted.

Performance of the Euroimmun Aspergillus Antigen ELISA for the Diagnosis of Invasive Pulmonary Aspergillosis in Bronchoalveolar Lavage Fluid.

Invasive pulmonary aspergillosis (IPA) is a life-threatening disease that affects mainly immunocompromised hosts. Galactomannan testing from serum and bronchoalveolar lavage fluid (BALF) represents a cornerstone in diagnosing the disease. Here, we evaluated the diagnostic performance of the novel Aspergillus-specific galactomannoprotein (GP) enzyme-linked immunosorbent assay (ELISA; Euroimmun Medizinische Labordiagnostika) compared with the established Platelia Aspergillus GM ELISA (GM; Bio-Rad Laboratories) for the detection of Aspergillus antigen in BALF. Using the GP ELISA, we retrospectively tested 115 BALF samples from 115 patients with clinical suspicion of IPA and GM analysis ordered in clinical routine. Spearman's correlation statistics and receiver operating characteristics (ROC) curve analysis were performed. Optimal cutoff values were determined using Youden's index. Of 115 patients, 1 patient fulfilled criteria for proven IPA, 42 for probable IPA, 15 for putative IPA, 10 for possible IPA, and 47 did not meet criteria for IPA. Sensitivities and specificities for differentiating proven/probable/putative versus no IPA (possible excluded) were 74% and 96% for BALF GP and 90% and 96% for BALF GM at the manufacturer-recommended cutoffs. Using the calculated optimal cutoff value of 12 pg/mL, sensitivity and specificity of the BALF GP were 90% and 96%, respectively. ROC curve analysis showed an area under the curve (AUC) of 0.959 (95% confidence interval [CI] of 0.923 to 0.995) for the GP ELISA and an AUC of 0.960 (95% CI of 0.921 to 0.999) for the GM ELISA for differentiating proven/probable/putative IPA versus no IPA. Spearman's correlation analysis showed a strong correlation between the ELISAs (rho = 0.809, P < 0.0001). The GP ELISA demonstrated strong correlation and test performance similar to that of the GM ELISA and could serve as an alternative test for BALF from patients at risk for IPA.

The Antifungal Pipeline: Fosmanogepix, Ibrexafungerp, Olorofim, Opelconazole, and Rezafungin.

The epidemiology of invasive fungal infections is changing, with new populations at risk and the emergence of resistance caused by the selective pressure from increased usage of antifungal agents in prophylaxis, empiric therapy, and agriculture. Limited antifungal therapeutic options are further challenged by drug-drug interactions, toxicity, and constraints in administration routes. Despite the need for more antifungal drug options, no new classes of antifungal drugs have become available over the last 2 decades, and only one single new agent from a known antifungal class has been approved in the last decade. Nevertheless, there is hope on the horizon, with a number of new antifungal classes in late-stage clinical development. In this review, we describe the mechanisms of drug resistance employed by fungi and extensively discuss the most promising drugs in development, including fosmanogepix (a novel Gwt1 enzyme inhibitor), ibrexafungerp (a first-in-class triterpenoid), olorofim (a novel dihyroorotate dehydrogenase enzyme inhibitor), opelconazole (a novel triazole optimized for inhalation), and rezafungin (an echinocandin designed to be dosed once weekly). We focus on the mechanism of action and pharmacokinetics, as well as the spectrum of activity and stages of clinical development. We also highlight the potential future role of these drugs and unmet needs.