Generic orphan drug substitution: a critical analysis of global practices and Saudi Arabia's perspective.

In an era of cost pressure, substituting generic drugs represents one of the main cost-containment strategies of healthcare systems. Despite the obvious financial benefits, in a minority of cases, substitution may require caution or even be contraindicated. In most jurisdictions, to obtain approval, the bioequivalence of generic products with the brand-name equivalent needs to be shown via bioavailability studies in healthy subjects. Rare diseases, defined as medical conditions with a low prevalence, are a group of heterogenous diseases that are typically severe, disabling, progressive, degenerative, and life-threatening or chronically debilitating, and disproportionally affect the very young and elderly. Despite these unique features of rare diseases, generic bioequivalence studies are typically carried out with single doses and exclude children or the elderly. Furthermore, the excipients and manufacturing processes for generic/biosimilar products can differ from the brand products which may affect the shelf-life of the product, its appearance, smell, taste, bioavailability, safety and potency. This may result in approval of generics/biosimilars which are not bioequivalent/comparable in their target population or that meet bioequivalence but not therapeutic equivalence criteria. Another concern relates to the interchangeability of generics and biosimilars which cannot be guaranteed due to the phenomenon of biocreep. This review summarizes potential concerns with generic substitution of orphan drugs and discusses potentially problematic cases including narrow therapeutic index drugs or critical conditions where therapeutic failure could lead to serious complications or even death. Finally, we put forward the need for refining regulatory frameworks, with emphasis on Saudi Arabia, for generic substitution and recent efforts toward this direction.

Diagnosis and Treatment Patterns of Chronic Thromboembolic Pulmonary Hypertension in Russia, Kazakhstan, Turkey, Lebanon, and Saudi Arabia: A Registry Study.

BACKGROUND: Patients with chronic thromboembolic pulmonary hypertension (CTEPH) in countries with limited resources have, to date, been poorly represented in registries. OBJECTIVE: This work assesses the epidemiology, diagnosis, hemodynamic and functional parameters, and treatment of CTEPH in Russia, Kazakhstan, Turkey, Lebanon, and Saudi Arabia. METHODS: A prospective, cohort, phase IV, observational registry with 3-year follow-up (n = 212) in patients aged ≥ 18 years diagnosed with CTEPH was created. Clinical, hemodynamic, and functional parameters were obtained at an initial visit, follow-up visits, and a final visit at the end of 3 years' observation or end of follow-up. Data were recorded on electronic case report forms. Parameters evaluated included 6-minute walking distance (6MWD), use of pulmonary endarterectomy (PEA), balloon pulmonary angioplasty (BPA), pulmonary hypertension (PH)-targeted therapy, and survival. All statistical analyses were exploratory and descriptive, and were performed in the overall population. RESULTS: The most common symptoms were typical of those expected for CTEPH. Almost 90% of patients underwent right heart catheterization at diagnosis or initial study visit. In total, 66 patients (31%) underwent PEA before the initial visit; 95 patients (45%) were considered operable, 115 (54%) were inoperable, and two (1%) had no operability data. Only 26 patients (12%) had been assessed for BPA at their initial visit. PH-targeted therapy was documented at diagnosis for 77 patients (36%), most commonly a phosphodiesterase type 5 inhibitor (23%). Use of PH-targeted therapy increased to 142 patients (67%) at the initial visit, remaining similar after 3 years. Use of riociguat increased from 6% of patients at diagnosis to 38% at 3 years. Between baseline and end of observation, results for patients with paired data showed an increase in 6MWD. Survival at the end of observation was 88%. CONCLUSIONS: These data highlight the current diagnosis and management of CTEPH in the participating countries. They show that early CTEPH diagnosis remains challenging, and use of off-label PH-targeted therapy is common. CLINICALTRIALS: gov: NCT02637050; registered December 2015.

A Challenging Case of Genetically and Histologically Diagnosed Pulmonary Veno-Occlusive Disease with Extracorporeal Life Support and Redo Lung Transplantation.

Background: Pulmonary veno-occlusive disease (PVOD) is a rare form of pulmonary arterial hypertension characterized by diffuse venous vasculopathy and increased pulmonary vascular resistance resulting in right-sided heart failure. Case Presentation. A 22-year-old female patient started to have dyspnea with minimal effort and was diagnosed to have pre-capillary pulmonary hypertension (PH) with right-sided heart failure. Initially, she was diagnosed to have idiopathic PH. She developed life-threatening pulmonary oedema and cardiogenic shock after pulmonary vasodilator therapy. A genetic study was done and revealed the eukaryotic translation initiation factor 2 alpha kinase 4 (EIF2AK4) gene on chromosome 15, which was diagnostic to heritable PVOD. After failure to achieve hemodynamic stabilization with conventional cardiopulmonary support measures, extracorporeal membrane oxygenation (ECMO) supported her till bilateral lung transplantation, which was unfortunately complicated by acute graft rejection. After a prolonged intensive care unit stay with 4-month ECMO support, the second bilateral lung transplantation was done, and the patient survived and was discharged. Conclusions: Clinical recognition of PVOD is crucial due to its challenging diagnosis, need for genetic study, rapid deterioration with pulmonary vasodilators, and bad prognosis. Lung transplantation is the definitive treatment for eligible candidates.

Prospective clinical assessment of patients with pulmonary arterial hypertension switched from bosentan to macitentan (POTENT).

Even though pulmonary arterial hypertension (PAH) remains an incurable disease, the combination of PAH-specific therapies allowed evolving from symptom-based strategies to others aiming to move patients to low-risk conditions. Endothelin-1 (ET-1) receptor antagonists emerged as specific-PAH drugs that can be used in combination with other specific therapies. This work aimed to perform a prospective clinical assessment of patients with PAH that switched from bosentan to macitentan (POTENT), due to inadequate response. POTENT is a prospective, open-label, single-arm, uncontrolled study including PAH patients from our ongoing SAUDIPH registry. It enrolled 50 PAH patients divided as follows: idiopathic/heritable pulmonary arterial hypertension (I/HPAH); n = 24; PAH associated with congenital heart disease, n = 19; PAH associated with connective tissue diseases, n = 5; and pulmonary veno-occlusive disease and/or pulmonary capillary haemangiomatosis (PVOD/PCH), n = 2. At baseline, most patients were in World Health Organization Functional Class (WHO FC) II/III (52.0%). After switching to macitentan, patients were more likely to be in WHO FC I/II (78%) and 22% of the overall cohort moved to a lower risk condition, with three low risk stratification parameters. Mean 6-min walking distance increased about 34 m after 12 months, with a significant mean change over time (12.63 ± 11.69 at month 3 vs. 40.75 ± 12.57 at month 12, p = 0.002). Most haemodynamic parameters decreased over time, with corresponding negative mean changes (p < 0.001). The safety of macitentan was confirmed by the absence of anaemia and liver injury; clinical worsening was observed only in a small group of patients. In general, macitentan might be a valid alternative to bosentan in PAH stable patients on combination therapy with insufficient clinical response, and presenting intermediate and high-risk parameters. We anticipate that studying this strategy in PAH subgroups would further clarify its potential and limitations.

Genetic basis of pulmonary arterial hypertension: a prospective study from a highly inbred population.

Pulmonary arterial hypertension (PAH), whether idiopathic PAH (IPAH), heritable PAH, or associated with other conditions, is a rare and potentially lethal disease characterized by progressive vascular changes. To date, there is limited data on the genetic basis of PAH in the Arab region, and none from Saudi Arabian patients. This study aims to identify genetic variations and to evaluate the frequency of risk genes associated to PAH, in Saudi Arabian patients. Adult PAH patients, diagnosed with IPAH and pulmonary veno-occlusive disease, of Saudi Arabian origin, were enrolled in this study. Forty-eight patients were subjected to whole-exome sequencing, with screening of 26 genes suggested to be associated with the disease. The median age at diagnosis was 29.5 years of age, with females accounting for 89.5% of our cohort population. Overall, we identified variations in nine genes previously associated with PAH, in 16 patients. Fourteen of these variants have not been described before. Plausible deleterious variants in risk genes were identified in 33.3% (n = 16/48) of our entire cohort and 25% of these cases carried variants in BMPR2 (n = 4/16). Our results highlight the genetic etiology of PAH in Saudi Arabia patients and provides new insights for the genetic diagnosis of familial and IPAH as well as for the identification of the biological pathways of the disease. This will enable the development of new target therapeutic strategies, for a disease with a high rate of morbidity and mortality.

Pulmonary hypertension in Saudi Arabia: First data from the SAUDIPH registry with a focus on pulmonary arterial hypertension.

BACKGROUND AND OBJECTIVE: This study presents the first results of 'SAUDIPH' registry, aiming to assess patient characteristics, treatment approach and clinical and survival outcomes in patients with PAH. METHODS: The registry enrolled patients with Group 1 and Group 4 PH under clinical management in a specialized tertiary care centre from 2004 to 2018. Changes from baseline to last follow-up visit were assessed. RESULTS: A total of 222 patients were enrolled, and Group 1 PH was the most frequent aetiology (57.7%). Mean age at diagnosis was 32 years. mPAP was 55.0 mm Hg and was higher for Group 1 PH (59.0 mm Hg, P < 0.001). At the last visit, most patients were on specific therapy (83.7%) and 30% shifted from FC III/IV to FC I/II. NT-proBNP improved by 29.2% in the overall population. The 1-, 3- and 5-year cumulative probabilities of survival were 95.6% (95% CI: 91.5-99.9%), 89.2% (95% CI: 82.1-96.9%) and 74.6% (95% CI: 59.4-93.7%), respectively. CHD-PAH demonstrated the best survival among Group 1 PAH with 1-, 3- and 5-year cumulative probability of 100%, 100%, and 75.0% (95% CI: 42.6-100), respectively. CONCLUSION: PAH was the most frequent aetiology and patients were younger at diagnosis compared to other cohorts. Most patients showed improvement in FC and NT-proBNP. The estimated 1-year survival was better than previous studies, possibly reflecting wider use of combination therapy and the high prevalence of CHD-PAH.

Chronic thromboembolic pulmonary hypertension in Saudi Arabia: preliminary results from the SAUDIPH registry.

BACKGROUND: Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare, progressive vascular disease with poor prognosis if left untreated. This study aims to assess the patient characteristics, treatment approach and clinical and survival outcomes for CTEPH patients enrolled in the Systematic Prospective Follow Up for Better Understanding of Clinical Characteristics of Patients with Pulmonary Hypertension Disease (SAUDIPH) registry. METHODS: This study presents a subanalysis of CTEPH patients enrolled in the SAUDIPH registry. This registry enrolled patients with pulmonary hypertension, established through right heart catheterisation, under clinical management at a specialised tertiary care centre. Patients received standard care during the period of the registry. RESULTS: At the time of this analysis, 64 CTEPH patients were enrolled in the registry. Mean age at diagnosis was 39.7 years and there was a female predominance (67.6%). At baseline, most patients were in World Health Organization functional classes III or IV (70.1%). At the last follow-up visit, most patients (63.2%) had undergone endarterectomy, showing significant improvement in disease severity from baseline. Patients who underwent endarterectomy showed numerically higher (p=0.126) probability of survival at 1 year (97.5%) versus those who did not undergo endarterectomy (94.4%). CONCLUSION: Patients were diagnosed at relatively young age, but still showed high disease severity, suggesting delay in diagnosis. Patients who underwent surgical treatment showed substantial improvements in clinical and haemodynamic parameters, while the remaining patients tended to show disease progression. The 96.6% 1-year cumulative probability of survival was high compared to previous studies.