The SARS-CoV-2 virus, with its clinical syndrome known as COVID-19, has a spike protein (S), nucleocapsid protein (N) that contains the RNA, membrane protein (M) and the envelope protein (E). The spike protein is responsible for initiating internalisation of the virus genome into human lung cells via ACE2 receptors in the nasopharyngeal and lung tissue, it protrudes on the outer surface and is made up of number of amino acids and glycoproteins. The integrity of the proteins (S, N, M \& E) is vital for viral functions, and formation of disulfide bonds between these have been suggested to play a vital role in the performance of the protein. The cleavage site after binding has been reported to split the spike glycoprotein, which is then reported to be supported with disulphide bonds. Binding then triggers proteolysis processed by transmembrane protease, serine 2 (TMPRSS2), furin, and perhaps other proteases, leading to fusion of viral and cellular membranes and thus target cells penetration. Hijacking of the cellular machinery then allows viral multiplication.

COVID-19 is a disease that has multiple facets including cytokine storm, thromboembolism and renal impairment, but the investigators believe mucinous secretions in the lung are of great importance to outcome. Early reports of lung pathology included cellular fibromyxoid exudate, proteinaceous exudate, massive luminal fibrous exudate and severe mucoid tracheal bronchitis. Autopsies in a cohort of fatal cases from northern Italy showed 'lumina often contained dense mucoid material. There are many pathological changes in the lungs, and these evolve over time. Early disease is characterised by neutrophilic exudative capillaritis with thrombosis. Late changes occurring on average from day 10 include diffuse alveolar damage, intravascular thrombosis, infection, disseminated intravascular coagulopathy (DIC) and later intra-alveolar fibroblast proliferation. Bronchoscopy was performed for acute hypoxia due to lung collapse in a COVID-19 patient, revealing a thick mucus plug. Multiple other reports of similar findings in bronchoscopies have been described where mucolytic therapy and suctioning have been advocated. Sputum characteristics in patients with severe COVID-19 correlate with outcome. Increasingly sticky sputum was associated with critical illness and considerably raised levels of MUC5AC in sputum in COVID-19 patients. There is a strong link between viral infection and mucus production via multiple signalling pathways including Interleukin (IL)6, IL10 and Tumour Necrosis Factor (TNF) whereby the cytokine storm causes sudden mucus hypersecretion.

Currently, there are few therapeutic agents of limited efficacy to treat or avoid the complications of COVID-19. An Australian pharmaceutical company has developed BromAc for the palliative treatment of highly mucinous tumors of the appendix and lung. This drug is composed of bromelain and acetylcysteine. During pre-clinical development, the sponsor found that BromAc® rapidly dissolved and removed tumour mucin, making it a potent mucolytic. BromAc® in combination have the ability, as shown in pre-clinical studies, to remove the mucin protective framework expressed by cancer including mucins MUC1, MUC2, MUC4, MUC5AC and MUC16. The sponsor has that BromAc breaks peptide and glycosidic linkages and disulphide bonds in tumour produced and respiratory mucin. It also combines synergistically with a variety of anticancer and antibacterial drugs.

In an in vitro study with Vero and CALU-3 cells infected by SARS-CoV-2 (MOI 1 to -4) and treated with BromAc, it was found that the drug was able to reduce the virus' ability to infect cells, demonstrating an antiviral potential against SARS-CoV-2. In addition to the anti-viral effect, BromAc is a potent mucolytic. In laboratory studies conducted in Brazil, BromAc (125ug or 250ug/ml plus 20mg/ml Acetylcysteine) resulted in complete dissolution of severe COVID-19 sputum within 30 minutes. BromAc was also shown to significantly down-regulate cytokines and chemokines in comparison to Acetylcysteine alone or control, specifically those important to COVID-19 cytokine storm CCL2, CCL3, IL-6, CXCL10. In vitro safety models have received nebulised and intranasal BromAc up to 500ug/20mg/ml three times daily for five days, with no evidence of toxicity.

In oncology, BromAc interferes with the effect of mucin, reduces cancer cell viability and profoundly enhances the effects of certain chemotherapy agents. MUC1, MUC2 and MUC5AC are highly expressed in gastrointestinal tumours. In brief, when investigating the effects of BromAc treatment on specific mucin isoforms in gastrointestinal carcinoma cells, the sponsor observed a significant decrease in the expression of MUC2 and MUC5AC in gastrointestinal LS174T cell lines. MUC1 and MUC5 are overexpressed and aberrantly glycosylated in most carcinomas, exploited by malignant cells to induce transformation and tumorigenicity. The sponsor's team have performed dose escalation animal safety studies with repeat injection in three different animal species into the peritoneum with doses of Bromelain up to 10mg/kg and Acetylcysteine 500mg/kg. There was no toxicity seen. BromAc was shown to remove mucin from the a range of human tumours in vivo, while none of the drugs worked alone. BromAc has the ability, as demonstrated in preclinical studies, to remove the protective structure of mucin expressed by cancer, including MUC1, MUC2, MUC4, MUC5B, MUC5AC and MUC16. BromAc's mechanism of action in removing peptide and glycoside bonds and disulfide bonds in mucin has also been shown. In addition, secondary infection in patients with COVID-19 might also be prevented or treated because of the effect of BromAc on biofilm. The sponsor has described efficacy in used endotracheal tubes at dissolving biofilm via nebulisation of BromAc, in addition to extensive laboratory work on pseudomonas aeruginosa and staphylococcus aureus established biofilms.

It is known that oxygen exchange is the main problem in patients with COVID-19 and hypoxia is one of the most serious effects, in which patients succumb to acute respiratory distress syndrome (ARDS). The development of mucinous sputum plugs in individuals infected with SARS-CoV-2 is variable in the early stages of the disease. In addition, 30-40% of patients who are in hospital have expectoration production, and in a recent study on pulmonary pathology in patients with COVID-19, subsequent tests revealed markedly increased levels of MUC1 and MUC5AC in sputum and trachea aspirate.

This study aims to examine the safety and efficacy of nebulised BromAc in a dose escalation phase I component. A phase I study applying the safe and effective dose in patients with moderate to severe COVID-19 will also be conducted. The primary endpoint in the phase I studies is the safety and tolerability of the planned doses. The hypothesis is that BromAc will be tolerated by patients and will result in mucus clearance, improving oxygenation and compliance in those that are ventilated.

This is a phase I study on the safety of BromAc, where 12 healthy volunteers who are otherwise well and remain in the outpatient setting will receive BromAc as a nebulised aerosol into the respiratory tract. BromAc is a product that combines two existing products (Bromelain and Acetylcysteine), along with 0.9% normal saline to be delivered into the respiratory tract via nebulised aerosol delivery through a mask. The participant will be assessed for symptoms and side effects.