PBI-4050 is an orally active lead drug candidate with excellent safety and efficacy profiles confirmed in several in vivo experiments targeting fibrosis. Fibrosis is a very complex process by which continuing inflammation causes vital organs to lose their function as normal tissue is replaced by fibrotic scar tissue. The proof of concept data generated to date confirms our lead drug candidates’ anti-fibrotic activity in several key organs including the kidneys, the heart, the lungs and the liver.
Currently, indications being pursued for PBI-4050 include Idiopathic Pulmonary Fibrosis (IPF), Alström syndrome, Chronic Kidney Diseases (CKD)/Diabetic Kidney Diseases, Metabolic Syndrome and Associated Type 2 Diabetes.
You can find more information on each of these indications below.
Idiopathic Pulmonary Fibrosis
Idiopathic pulmonary fibrosis (IPF) is a chronic, devastating, and ultimately fatal disease characterized by a progressive decline in lung function. It is a specific type of interstitial lung disease in which the small air sacs of the lung, the “alveoli,” gradually become replaced by fibrotic (scar) tissue and is the cause of worsening dyspnea (shortness of breath). IPF is usually associated with a poor prognosis. The term ‘idiopathic’ is used because the cause of pulmonary fibrosis is still unknown. IPF usually occurs in adult individuals of between 50 and 70 years of age, particularly those with a history of cigarette smoking, and affects men more often than women.
Acute exacerbation of IPF (AE-IPF) is defined as a sudden acceleration of the disease or an idiopathic acute injury superimposed on diseased lung tissue that leads to a significant decline in lung function. An AE-IPF is associated with a mortality rate as high as 85%, with mean survival periods between 3 to 13 days.
IPF affects about 130,000 people in the United States, with about 48,000 new cases diagnosed annually. Approximately 40,000 people die each year with IPF, a similar number of deaths to those due to breast cancer. The 5-year mortality rate for patients with IPF is estimated to range from 50% to 70%.
Prometic has announced positive results from its completed open label Phase 2 clinical trial in subjects suffering from idiopathic pulmonary fibrosis (“IPF”). In addition to demonstrating that PBI-4050 is safe and very well tolerated, an objective of this study was to seek early evidence of a clinical benefit with PBI-4050 treatment, whether administered alone or in addition to either of the drugs approved for the treatment of IPF, nintedanib or pirfenidone.
A total of 40 subjects were enrolled in the study conducted in 6 sites across Canada and all have completed the 12 weeks of treatment; 9 subjects received PBI-4050 alone, 16 received PBI-4050 & nintedanib and 15 received PBI-4050 & pirfenidone. The baseline characteristics of the subjects enrolled in this study were similar to those enrolled in prior IPF randomized controlled studies conducted by other pharmaceutical companies, namely ASCEND and INPULSIS.
As was demonstrated in these previously mentioned large clinical trials, IPF subjects typically experience a progressive decline in respiratory function. In contrast, in the ProMetic clinical study, the respiratory function of the subjects, measured as the forced vital capacity (FVC (ml)), remained stable after 12 weeks of treatment, in subjects treated with PBI-4050 alone and in those receiving PBI-4050 combined with nintedanib for the treatment of IPF and was superior to that of those subjects treated with PBI-4050 combined with pirfenidone for the treatment of IPF.
Metabolic Syndrome And Associated Type 2 Diabetes
Some preclinical models used to demonstrate the pharmacological activity of PBI-4050 involve the presence of diabetes, obesity, hypertension leading to an accelerated rate of fibrosis in the liver, kidney and pancreas and premature death. Mice models such as the db/db eNOS-/- mouse model performed at the University of Vanderbilt or db/db uni-nephrectomized mouse model performed at Prometic helped demonstrate that the combined effect of PBI-4050 in reducing fibrosis and macrophage infiltration in fat tissue, in the pancreas, the kidney and the liver not only improved the status of these organs and the survival of the animals compared to control, but also significantly reduced blood glucose level. Given that the demonstration of fibrosis reduction in humans requires trials with long term exposure, the Corporation initiated a first phase 2 trial in patients who present symptoms like the ones described in the db/db eNOS-/- mouse model: Type 2 diabetes with metabolic syndrome (T2DMS). While this is not a medical indication that the Corporation seeks to ultimately target commercially with PBI-4050, the purpose of this study was to quickly ascertain whether the pharmacological activity observed in preclinical animal models translated to humans. Particular attention was placed on the blood sugar levels in a phase 2 clinical trial given that this effect should be measurable in a manner of 8 to 12 weeks.
The International Diabetes Federation estimates that in 2013 there were 300 million diabetics world-wide, and that that number will increase to 600 million by the year 2035. The Center for Disease Control estimates that 1 of 3 children born in the U.S. during the year 2000 will develop diabetes during their lifetime.
This study met its primary and secondary endpoints. In addition to safety and tolerability, the study evaluated the effects of PBI-4050 on metabolic syndrome parameters and on pro-inflammatory/fibrotic and diabetic biomarkers in blood and urine. In this open label Phase 2 clinical trial, PBI-4050 (800 mg) was administered once daily to 24 patients already being treated with “standard of care” drug regimens for a period of 12 weeks. Twelve of these patients were enrolled in an additional 12 week extension throughout which the efficacy and safety observed at 12 weeks was also maintained at 24 weeks PBI-4050 has been well tolerated with no serious drug related adverse events.
The pharmacological activity of PBI-4050 was confirmed through the clinically significant reduction in glycated hemoglobin concentration (“HbA1c”) between screening and Week 12. For instance, the 15 patients with a screening (HbA1c) ≥ 7.5 experienced a clinically significant mean decrease of – 0.75% (p = 0.0004). The 12 patients who participated in the study’s 12-week extension had a mean HbA1c of 7.7 at screening and experienced a reduction of – 0.8% at week 24. These clinical results bode well for PBI-4547 which has demonstrated even more pronounced effects on metabolic parameters in preclinical models compared to PBI-4050.
Alström syndrome is a rare inherited autosomal recessive syndrome characterized by the onset of obesity in childhood or adolescence, Type 2 diabetes with severe insulin resistance, dyslipidemia, hypertension and severe multi-organ fibrosis, involving the liver, kidney and heart.
Alström syndrome is also characterized by a progressive loss of vision and hearing, a form of heart disease that enlarges and weakens the heart muscle (dilated cardiomyopathy), and short stature. This disorder can also cause serious or life-threatening medical problems involving the liver, kidneys, bladder, and lungs. Some individuals with Alström syndrome have a skin condition called acanthosis nigricans, which causes the skin in body folds and creases to become thick, dark, and velvety. The signs and symptoms of Alström syndrome vary in severity, and not all affected individuals have all of the characteristic features of the disorder.
Alström syndrome affects males and females in equal numbers. The exact incidence is unknown. Estimates have ranged from 1 in 10,000 to less than 1 in 1,000,000 individuals in the general population. Approximately 1200 affected individuals have been identified worldwide
The on-going AS study is an open-label, single-arm, phase 2 clinical trial in which the patients are treated with PBI-4050 (800 mg) once daily. Each patient is evaluated against their respective baseline and against their respective historical disease progression trend whenever available, given the severity of their medical conditions. The clinical study has enrolled 12 subjects.
To date, the subjects have received 52 weeks of treatment with PBI-4050. PBI-4050’s safety and tolerability has been confirmed over this extended period. A brief summary of the most significant findings is presented below.
Fibroscan results from the 10 subjects who received at least 36 weeks of treatment showed a statistically significant improvement in the measure of liver stiffness, from a mean of 10.2 kPa at baseline to a mean of 8.1 kPa at last measurement, an absolute decrease of 2.1 kPa (p = 0.0219, 95% CI -3.52, -0.46). Fibroscan is a non-invasive technique for clinical assessment of liver fibrosis with a high degree of accuracy and reproducibility, especially in patients with established fibrosis (≥ F2) (Cassinotto 2016). FibroScan® measurements for all patients were carried out by a single, experienced operator. To ensure test reliability, a minimum of 10 valid readings were taken per patient, with a required success rate of at least 60% and an interquartile range of <=30% of the median value.
Liver MRI data also indicated a mean reduction of -11% in the T1-corrected score between baseline and last available measurement (p=0.0195, 95% CI: -92.3, -9.8), which supports an improvement of liver fibrosis.
In addition to the preliminary evidence of efficacy observed on liver fibrosis presented above, analysis of the interim cardiac MRI data indicates a reduction of cardiac fibrosis in each patient after initiation of treatment with PBI-4050 (p<0.001).
A major reduction of key urine biomarkers of ongoing kidney injury in the 12 subjects for whom Week 24 results are available was also observed. Finally, positive effects on other parameters of the liver and the fat tissue have also been observed and will be presented at forthcoming scientific conferences.
The Corporation also recently published summary liver and fat biopsies analysis data. Dysfunctional adipose tissue involving enlargement of fat cells, is known to increase cardiometabolic risk. In AS patients, fat tissue is characterized with significant enlargement and coalescence of adipocytes forming giant vesicular vacuolation/steatosis. After 24 weeks of treatment with PBI-4050, adipocytes were more distinct, were smaller in size and no coalescence was observed.
The trial is being performed at the specialty center for the care of UK patients with Alström syndrome at the Queen Elizabeth Hospital, Birmingham, UK. This center has recently published data showing that many of these patients show evidence of non-alcoholic fatty liver disease and advanced liver fibrosis at an early age, confirming previous publications showing a very high incidence of progression of NAFLD into liver cirrhosis with associated mortality in Alström patients.
Chronic Kidney Diseases/Diabetic Kidney Diseases
Chronic kidney disease (CKD), also known as chronic renal disease, is a progressive loss in renal function over a period of months or years. Professional guidelines classify the severity of CKD in five stages, with stage 1 being the mildest and usually causing few symptoms and stage 5 being a severe illness with poor life expectancy if untreated. Stage 5 CKD is often called end-stage kidney disease, end-stage renal disease, or end-stage kidney failure, and is largely synonymous with the now outdated terms chronic renal failure or chronic kidney failure; and usually means the patient requires renal replacement therapy, which may involve a form of dialysis, but ideally constitutes a kidney transplant.
Twenty six million patients in the U.S. alone are diagnosed with chronic kidney diseases (“CKD”). Patients with severe CKD stages (3 and 4) suffer from a gradual and accelerated loss of their renal function (end stage renal disease or ESRD) leading to the need for maintenance dialysis or kidney transplant.
PBI-4050 has completed a randomized, double-blind, placebo-controlled, multi-dose phase Ib study to demonstrate the safety and tolerability of PBI-4050 and to determine the pharmacokinetic profile of PBI-4050 following multiple oral doses over 10 days in patients with stage 3b or 4 stable renal impairment. The trial was conducted in 8 patients with 6 patients receiving PBI-4050 and 2 patients receiving matching placebo.
The Corporation plans to enter into partnerships for other larger medical indications and or geographical regions requiring a much more substantial local commercial reach and resources. It is generally not Prometic’s intention to independently undertake late-stage clinical trials (phase 3) in large indications, such as Idiopathic Pulmonary Fibrosis (“IPF”), Chronic Kidney Disease (“CKD”) or Diabetic Kidney Disease (“DKD”) without the support of a strategic venture or big pharma partner.