Novel investigational therapies for treating pulmonary arterial hypertension

Introduction: Despite the development of new therapies, pulmonary arterial hypertension (PAH) has a median survival of 6 – 7 years. This is likely because the currently approved therapies affect predominantly pulmonary vasoconstriction. The past two decades have witnessed greater insights into the pathogenesis of PAH, from the role of inflammation to molecular signaling and epigenetics. Multiple pharmacological agents targeting these newly identified pathways are currently being investigated in preclinical and early clinical studies.

Areas covered: Herein, the authors review the modalities targeting recently identified molecular targets in PAH. These include: prostaglandin receptor agonists, agents that alter the cyclic adenosine monophosphate and cyclic guanosine monophosphate pathways, vasoactive peptides, receptor tyrosine kinase inhibitors, Rho-kinase inhibitors, serotonin pathway inhibitors, anti-inflammatory agents, antioxidants, agents that alter nitric oxide signaling, various cardiac medications, mitochondrial metabolism modifying agents, epigenetic agents and cell-based therapies. The authors also address the gaps in the knowledge and explain why certain agents may or may not be promising PAH pharmacotherapeutics.

Expert opinion: Newer agents target multiple pathways including vasoconstriction, cellular proliferation and inflammatory response. And while only a few of the current investigational drugs will likely be further developed, the authors expect that the next two decades will bring some major breakthroughs in PAH management.     

Investigational drugs for nasopharyngeal carcinoma

Introduction: Nasopharyngeal carcinoma (NPC) is endemic to Southern China and Asia and is etiologically associated with the Epstein Barr virus (EBV). Whole exome and genome sequencing (WES, WGS) studies of NPC have reported several actionable therapeutic targets, and that the mutational load of NPC maybe comparable to that of squamous head and neck cancer. These unique biological characteristics have been exploited as potential targets and a wide range of investigational drugs are being investigated in clinical trials.

Area covered: This review focused on the latest clinical development of the most promising classes of investigational agents in the treatment of advanced NPC. These include inhibitors of tumor angiogenesis, kinase signaling pathways and immunotherapy.

Expert opinion: Checkpoint inhibitors and EBV-specific T-cell therapy have shown promising activity in early phase clinical trials, and are being further evaluated in randomized studies. For patients whose tumors express genetic alterations that are known to predict response to kinase inhibitors, novel trial designs such as an ‘Umbrella’ study may be considered given the abundance of targeted agents that are now available for clinical evaluation. It is envisioned that regulatory approval for new drugs for advanced NPC will occur in the near future.     

Emerging drugs for the treatment of gastrointestinal stromal tumour

Introduction: Tyrosine kinase inhibitors (TKIs) have transformed the treatment landscape for patients with gastrointestinal stromal tumors (GIST). Unfortunately, resistance to the currently approved TKIs poses a huge challenge, and patients are in need of additional therapeutic options. Fortunately, many novel therapeutic approaches are being tested in treatment of GIST to overcome resistance to the approved TKIs

Areas covered: We performed an extensive literature (PUBMED) search to identify emerging drugs being tested in treatment of GIST in early phase clinical trials. We discuss recent ongoing research and emerging novel inhibitors of KIT and PDGFRA receptors, inhibitors in downstream signaling pathways (mTOR and PIK3 inhibitors), inhibitors of other potential targets including ETV1/MEK, MET, FGFR, IGF1R, histone deacetylase inhibitors, heat shock protein 90 inhibitors, cyclin-dependent kinase inhibitors and immune checkpoint inhibitors in treatment of GIST

Expert opinion: Multiple agents are under evaluation; those that benefit GIST patients with imatinib resistant mutations, or those with benefit in patients refractory to approved agents are most likely to be developed in this disease. The role of immunotherapy for GIST is still investigational.     

Treating pulmonary hypertension in pediatrics

Introduction: Pulmonary hypertension is a hemodynamic condition occurring rarely in pediatrics. Nevertheless, it is associated with significant morbidity and mortality. When characterized by progressive pulmonary vascular structural changes, the disease is called pulmonary arterial hypertension (PAH). It results in increased pulmonary vascular resistance and eventual right ventricular failure. In the vast majority of cases, pediatric PAH is idiopathic or associated with congenital heart disease, and, contrary to adult PAH, is rarely associated with connective tissue, portal hypertension, HIV infection or thromboembolic disease.

Areas covered: This article reviews the current drug therapies available for the management of pediatric PAH. These treatments target the recognized pathophysiological pathways of PAH with endothelin-1 receptor antagonists, prostacyclin analogs and PDE type 5 inhibitors. New treatments and explored pathways are briefly discussed.

Expert opinion: Although there is still no cure for PAH, quality of life and survival have been improved significantly with specific drug therapies. Nevertheless, management of pediatric PAH remains challenging, and depends mainly on results from adult clinical trials and pediatric experts. Further research on PAH-specific treatments in the pediatric population and data from international registries are needed to identify optimal therapeutic strategies and treatment goals in the pediatric population.     

Investigational HIV integrase inhibitors in phase I and phase II clinical trials

Introduction: To date, three HIV integrase strand transfer inhibitors (INSTIs), i.e. raltegravir, elvitegravir and dolutegravir, have been approved for clinical use. Recent research has focused on new integrase inhibitors including those targeting non-catalytic sites of HIV integrase.

Areas covered: This paper reviews two investigational INSTIs in phase I and II clinical trials, bictegravir (BIC) and cabotegravir (CAB), as well as an investigational noncatalytic integrase inhibitor (NCINI) termed BI 224436.

Expert opinion: Data from phase I and II clinical trials demonstrate that CAB has good efficacy and is well-tolerated. CAB is promising because it can be formulated both orally and as a long-acting (LA) injectable for treatment and prevention of HIV infection. Since LA-CAB formulation offers the possibility of favourable dosing, it may help individuals who struggle with adherence issues. BIC also represents a promising safe, effective and well-tolerated drug that can be administered as a single once-daily regimen in coformulation with emtricitabine and tenofovir alafenamide (FTC/TAF). Ongoing phase III trials should clarify optimal doses and reveal the potential clinical advantages of these new drugs and formulations over other current regimens. Exploration of novel HIV integrase inhibitors acting through mechanisms different from those of INSTIs is still needed.     

Expanded access to investigational drugs: balancing patient safety with potential therapeutic benefits

Introduction: Expanded access is the use of an investigational product by patients with serious medical conditions without participation in a clinical trial. It is a complicated process involving the collaboration of many parties and pharmaceutical companies. Ongoing efforts focus on accelerating expanded access procedures in the best interest of patients with cancer.

Areas covered: We review the regulatory and ethical challenges encountered in efforts to optimize expanded access.

Expert opinion: In the era of personalized medicine, patients may benefit from novel therapeutic agents that demonstrate encouraging results in early studies. However, drug approval is a lengthy and cumbersome procedure that might exceed the time frame of a life-threatening disease. Expanded access provides options to patients with unmet needs. It may provide informative safety and efficacy data to the manufacturers and the scientific and regulatory organizations.

Ongoing efforts are being made by global governmental and scientific committees, regulatory agencies, and patient organizations to address the ethical and regulatory issues and to optimize the expanded access process. Their goal is to expand access to promising novel drugs for individual patients and to accelerate the necessary procedures while preserving patient safety.     

Early clinical development of epidermal growth factor receptor targeted therapy in breast cancer

Introduction: Epidermal growth factor receptor (EGFR) targeted treatment has been evaluated but has not shown a clear clinical benefit for breast cancer. This review article aims to consider the knowledge of the biological background of EGFR pathways in dissecting clinical studies of EGFR targeted treatment in breast cancer.

Areas covered: This review focuses on the role of the EGFR pathway and the investigational drugs that target EGFR for breast cancer.

Expert opinion: Recent studies have indicated that EGFR targeted therapy for breast cancer has some promising effects for patients with triple-negative breast cancer, basal-like breast cancer, and inflammatory breast cancer. However, predictive and prognostic biomarkers for EGFR targeted therapy have not been identified. The overexpression or amplification of EGFR itself may not be the true factor of induction of the canonical pathway as an oncogenic driver of breast cancer. Instead, downstream, non-canonical pathways related to EGFR may contribute to some aspects of the biological behavior of breast cancer; therefore, the blockade of the receptor could result in sufficient suppression of downstream pathways to inhibit the aggressive behavior of breast cancer. Mechanistic studies to investigate the dynamic interaction between the EGFR pathway and non-canonical pathways are warranted.     

Safety and effectiveness of tadalafil in patients with pulmonary arterial hypertension: Japanese post-marketing surveillance data

Objective: To evaluate the long-term safety and effectiveness of tadalafil in patients with pulmonary arterial hypertension (PAH) in real-world clinical practice.

Methods: This prospective, multicenter, noninterventional, post-marketing surveillance included patients with PAH who were observed for up to 2 years after initiation of tadalafil. Safety was assessed by analyzing the frequency of adverse drug reactions (ADRs), discontinuations due to adverse events (AEs), and serious adverse drug reactions (SADRs). Effectiveness measurements included the assessment of the change in World Health Organization (WHO) functional classification of PAH, 6-minute walk test, cardiac catheterization, and echocardiography.

Results: Among 1676 patients analyzed for safety, the overall incidence of ADRs was 31.2%. The common ADRs (≥1.0%) were headache (7.0%), diarrhea (1.9%), platelet count decreased (1.8%), anemia, epistaxis, and nausea (1.6% each), flushing (1.3%), hepatic function abnormal (1.1%), hot flush, and myalgia (1.0% each). The common SADRs (≥0.3%) were cardiac failure (0.7%), interstitial lung disease, worsening of PAH, and platelet count decreased (0.3% each). Among 1556 patients analyzed for effectiveness, the percentages of patients with improvement of WHO functional class at 3 months, 1 year, and 2 years after the initiation of tadalafil, and last observation were 17.1%, 24.8%, 28.9%, and 22.5%, respectively. At all observation points (except pulmonary regurgitation pressure gradient at end diastole at 3 months), the mean 6-minute walk distance, cardiac catheterization, and echocardiogram measurements showed statistically significant improvement.

Conclusion: This surveillance demonstrated that tadalafil has favorable safety and effectiveness profiles for long-term use in patients with PAH in Japan.     

Evaluation of WO2017098421: GSK’s benzothiazine compounds as CD73 inhibitor filings

Introduction: There are considerable interests in the development of novel small-molecule CD73 inhibitors for the treatment of cancers, autoimmune diseases, precancerous syndromes, and other diseases associated with CD73 activity.

Areas covered: The application claims novel substituted benzothiadiazine derivatives as CD73 inhibitors for the treatment of cancer, precancerous syndromes, AIDS, autoimmune diseases, infections, atherosclerosis, and ischemia-reperfusion injury. Many of the exemplified compounds have pIC50 values between 5 to 8.4 against CD73.

Expert Opinion: These benzothiadiazine derivatives provide good leads for the discovery of potent CD73 inhibitors for the treatment of cancer and other diseases mediated by adenosine and its action on adenosine receptors.     

Human factors and usability engineering in the development of SMT-101 for the treatment of pulmonary arterial hypertension

Background: SMT-101, a novel, proprietary, water-resistant wearable infusion pump prefilled with a preset dosage of treprostinil, was designed to address many of the administration-related shortcomings of existing parenteral therapy for pulmonary arterial hypertension (PAH). The objective of the human factors (HF) program was to demonstrate that the SMT-101 system is safe and effective when used by patients with PAH, their caregivers, or healthcare providers.

Methods: The HF program for SMT-101 consisted of 8 studies (148 participants): an ethnographic study, an online survey of patients with PAH, 4 formative studies, a study of the instructions for use (IFU), and a summative study for validation. The pump and IFU were iteratively modified using observational data and participant feedback to inform subsequent improvements throughout the HF program to optimize safe use of SMT-101 before the final study.

Results: The results of the summative study demonstrated that the design of the SMT-101 wearable, pre-filled infusion pump and IFU are safe and effective for use.

Conclusions: In accordance with regulatory guidelines, the usability and HF aspects of SMT-101 were developed and refined through a rigorous HF program in patients with PAH and healthcare providers, which culminated in a summative study that validated the usability and use-safety of SMT-101.     

Investigational opioid antagonists for treating opioid-induced bowel dysfunction

Introduction: Opioids have been highlighted for their role in pain relief among cancer and non-cancer patients. Novel agents have been investigated to reduce opioid-induced constipation (OIC) as the main adverse effect that may lead to treatment discontinuation. Development of peripherally acting mu-opioid receptor antagonists (PAMORA) has resulted in a novel approach to preserve the efficacy of pain control along with less OIC.

Areas covered: Clinical evidence for investigational PAMORAs was reviewed and clinical trials on investigational agents to reduce OIC were included. TD-1211 is currently being evaluated in Phase II clinical trial. Oxycodone-naltrexone and ADL-5945 went through Phase III clinical trials, but have been discontinued.

Expert opinion: There is a substantial need to develop agents with specific pharmacokinetic properties to meet the needs of patients with underlying diseases. Holding the efficacy of a medicine with the highest selectivity on targeted receptors and the least adverse effects is the main approach in upcoming investigations to improve patients’ quality of life (QoL). Novel agents to reduce opioid-induced bowel dysfunction (OIBD) that do not reverse peripherally mediated pain analgesia are of great interest. Direct comparison of available agents in this field is lacking in the literature.     

Identification of spirocyclic or phosphate substituted quinolizine derivatives as novel HIV-1 integrase inhibitors: a patent evaluation of WO2016094197A1, WO2016094198A1 and WO2016154527A1

Introduction: Highly active antiretroviral therapy (HAART) has been widely adopted to control the HIV-1 infection successfully. HIV-1 integrase (IN) inhibitors are primary drugs in HAART regimens targeting integration step in the HIV-1 life cycle. However, due to the emergence of viral resistance and cross-resistance amongst drugs, there is a pressing need for new and potent IN inhibitors. This review covers the three patents describing spirocyclic and phosphate substituted quinolizine derivatives as novel HIV-1 IN inhibitors for the discovery of new anti-HIV-1 drug candidates.

Areas covered: This review is focused on spirocyclic and phosphate substituted quinolizine derivatives bearing the same metal chelation scaffold as novel HIV-1 IN inhibitors.

Expert opinion: Generally, privileged structure-based optimizations have emerged as an effective approach to discover newly antiviral agents. More generally, due to the similar Mg²⁺ catalytic active centers of endoribonucleases, some divalent metal ion chelators were found to be versatile binders targeting multiple metalloenzymes. Therefore, privileged structure-based scaffold re-evolution is an important tactic to identify new chemotypes, to explore unknown biological activities, or to provide effective ligands for multiple targets by modifying the existing active compounds.     

Dosing strategies to optimize currently available anti-MRSA treatment options (Part 2: PO options)

Introduction: Methicillin-resistant Staphylococcus aureus (MRSA) is a problematic pathogen in both outpatient and inpatient settings. Research to optimize the dosing of these agents is needed to slow the development of antimicrobial resistance and to decrease the likelihood of clinical failure.

Areas covered: This review summarizes the available data for orally administered antimicrobials routinely used as monotherapy for MRSA infections. We make recommendations and highlight the current gaps in the literature. A PubMed (1966 – Present) search was performed to identify relevant literature for this review.

Expert commentary: There is a vast divide in the amount of pharmacokinetic/pharmacodynamic data to guide dosing decisions for older MRSA agents compared with the oxazolidenones.

Five-year view: Additional retrospective data will become available for the older MRSA agents in severe MRSA infections.     

Clinical pharmacology,efficacy, and safety of selexipag for the treatment of pulmonary arterial hypertension

Introduction: Selexipag is the first oral, non-prostanoid, selective prostacyclin receptor (IP receptor) agonist, approved for the long-term treatment of pulmonary arterial hypertension (PAH) in adult patients.

Areas covered: This article reviews the clinical pharmacology, efficacy, and safety of selexipag in the treatment of PAH.

Expert opinion: Selexipag is the first oral drug that selectively targets the prostacyclin pathway, and has evidence of long-term efficacy and safety. In the global phase 3 study GRIPHON (NCT01106014) in PAH patients, selexipag significantly reduced the risk of the primary composite outcome of morbidity/mortality (M/M). The adverse events in the selexipag group were consistent with the known side effects of prostacyclin, including headache, nausea, jaw pain, and diarrhea. Importantly, selexipag was efficacious and safe irrespective of whether or not patients were already receiving other PAH therapies. With selexipag approval, triple oral combination therapy addressing three important pathways is available for patients with PAH. Selexipag has one major metabolite, ACT-333679, which is also a selective IP receptor agonist, with 37-fold higher potency than selexipag. Pharmacokinetic properties of ACT-333679 permit twice-daily dosing of selexipag, providing a more convenient treatment compared to prostacyclin or its analogs. For patients with moderate hepatic impairment a once-daily regimen is recommended.     

Pharmacological interventions for stress ulcer prophylaxis in critically ill patients: a mixed treatment comparison network meta-analysis and a recursive cumulative meta-analysis

Background: Proton pump inhibitors (PPI), histamine-2 receptor antagonists (H2RA), sucralfate and antacids are the commonly administered agents for stress ulcer prophylaxis (SUP) in critically ill patients. The authors of this paper have conducted a network meta-analysis to compare the efficacy of these agents in SUP.

Methods: Electronic databases were searched for randomized controlled trials, cohort studies and conference abstracts for studies comparing a SUP agent in critically ill patients to another active SUP agent or placebo. Overt, occult and clinically significant upper gastro-intestinal (UGI) bleeding, all-cause mortality, pneumonia, gastric colonization and ICU length of stay were considered as the outcome measures. A random effects model was used to generate pooled estimates.

Results: A total of 53 studies (4258 participants) were included. The pooled estimates were in favor of PPI and sucralfate for the overt UGI bleeding. PPI and H2RA bolus were associated with increased risk of gastric colonization and pneumonia.

Conclusions: SUP in critically ill patients was not associated with any benefit with regard to clinically significant bleeding episodes. However, PPI and sucralfate significantly reduces overt UGI bleeding. On the contrary, PPI and H2RA bolus are associated with an increased risk of gastric colonization and pneumonia.     

Pharmacotherapy for treating metastatic clear cell renal cell carcinoma

Introduction: Over the past decade metastatic renal cell carcinoma (RCC) treatment landscape has dramatically evolved from the era of cytokines-based immunotherapy (which benefited very few patients, at the expenses of high toxicities) to the present era of targeted agents and novel immunotherapeutics, greatly improving the prognosis of our patients.

Areas covered: Here we have reviewed the present status of the medical treatment of metastatic RCC. To do this, we interrogated the Medline database, as well as the proceedings of the main Oncological and Urological conferences for the relevant trials coducted so far.

Expert opinion: Despite all the advances made in these relatively few years, further improvements are needed, since none of the available agents proved able to cure even a sigle metastatic RCC patient. In particular, advances are awaited from the results of ongoing trial of combinations of different immune checkpoint inhibitors and of immune checkpoint inhibitors with anti-VEGF/VEGFRs agents. Furthermore, a better understanding of the molecular escape pathways used by the tumor to overcome VEGFR blockade or immune activation will hopefully bring soon to the clinic more active, tailored treatments, to be used in second line and beyond.     

Early investigational antibiotics for the treatment of acute exacerbations of chronic bronchitis

Introduction: Acute exacerbations in patients with chronic bronchitis are a leading cause of hospitalizations and death. Bacteria contribute significantly to such exacerbations. The aim of this review was to explore the potential role of investigational antibiotics in the treatment of these episodes.

Areas covered: The available literature in PubMed database, in websites related to investigational drugs and in websites of the producing companies has been searched. The in vitro activity against pathogens involved in acute exacerbations of chronic bronchitis and the pharmacokinetic profile of antibiotics currently under development were taken into consideration for inclusion in the review.

Expert opinion: Several novel antimicrobial agents have completed preclinical and Phase I studies and were well-tolerated. Further investigation is mandatory in order to evaluate their future in treatment of chronic bronchitis exacerbations and discover potential advantages compared to already approved antimicrobials.     

Treatment options for nonalcoholic steatohepatitis - a safety evaluation

Introduction: There is an urgent as yet unmet need to develop highly effective and safe therapeutics for nonalcoholic fatty liver disease (NAFLD). The remarkable progress in understanding NAFLD pathogenesis allowed the identification of injury pathways which may be recruited as therapy targets.

Areas covered: This article reviews the safety and tolerability data of the NAFLD therapies and explains the mechanistic basis for each of the established and investigational drugs. Treatment targets include: weight loss, anti-metabolic agents such as lipid lowering and anti-diabetic drugs, inflammation, fibrosis and others such as targeting gut microbiota, immune modulation and apoptosis.

Expert opinion: Current therapies continue to remain suboptimal. Weight loss is effective but hard to achieve. Traditional and endoscopic bariatric procedures are promising although more randomized trials are needed and the long-term safety remains to be established. Clinical trials have demonstrated the efficacy of several drugs for the treatment of NASH. Of these, there remains some uncertainty about the long-term safety of vitamin E. Pioglitazone is associated with osteopenia, fluid retention and weight gain. Obeticholic acid causes pruritus in a substantial proportion of subjects and elafibranor has been associated with transient rises in creatinine. Several exciting therapies are under development and results of clinical and post-marketing trials will help elucidate their safety.     

New pharmacotherapy options for pulmonary arterial hypertension

Introduction: Epoprostenol was the first targeted therapy available for the treatment of pulmonary arterial hypertension (PAH). Since then great advances in our knowledge of the disease have been made and the spectrum of therapeutic options for PAH has expanded. After an overview of current available treatments, this article describes the new pharmacotherapy options and their place in the management of PAH.

Areas covered: This paper is based on a literature search and the review of studies published on PAH pharmacotherapy using the MEDLINE database.

Expert opinion: The last decade has been particularly important in PAH management with the emergence of six new molecules, the development of novel routes of administration and improvement of pharmacokinetics. Moreover, pediatric formulations have been developed. However, further research is required to inform clinicians regarding optimal choices of combination therapies (progressive add-on therapy or upfront combination therapy, selection of associated molecules regarding the patient’s profile...), to continue to improve the quality of life of patients with new drugs and to reach the ultimate goal of curing the disease.