TESTING SM001 (Tigerase)
RESULTS OF NONCLINICAL STUDIES
An FDA recommended animal model of sarcoidosis (Hu 2017) was used to evaluate the efficacy of inhaled DNase1 to reduce Propionibacterium acnes-induced pulmonary sarcoidosis. Propionibacterium acnes (P. acnes) is the microorganism isolated from sarcoid lesions. P. acnes trigger factor protein causes a cellular immune response only in sarcoid patients and induces pulmonary granulomas in mice sensitized with the protein and adjuvant (Eishi 2013). This model is believed to mimic the human pathological process of pulmonary sarcoidosis through initiation of granuloma formation via a bacterium found in lungs of patients with pulmonary sarcoidosis. A complex of protein and bacterial DNA may be the initial inciting antigen that triggers the subsequent immunological cascade leading to granuloma formation (Nicastro and Tukel 2019). The DNase1 activity of the inhaled enzyme is postulated to reduce or eliminate the antigenic complex and thus inhibit granuloma formation.
Mice were treated with heat-killed P. acnes 28 days before therapy to ensure that the inflammation in the lung of a sarcoidosis like condition is fully established prior to the initiation of therapy. Introduction of heat-killed P. acnes was based on the following:
SCHEDULE:
- Day Zero (sensitization): The mice were injected intraperitonially with 250 μL of the 2 mg/mL P. acnes suspension.
- Day 14: The mice were challenged with 50 μL of the 10 mg/mL P. acnes suspension (intratracheal instillation).
- Day 28: The mice were challenged with 50 μL of the 10 mg/mL P. acnes suspension (intratracheal instillation).
DNase1 inhalation at 5 μg per mouse per day following the induction of granulomatous inflammation had a protective effect on lung inflammation. BAL leukocytes content was three times lower in mice receiving DNase1, when compared to vehicle treated mice (2.49 x105 and 7.81×105, respectively). In BAL, importantly, IFN- and IL-6, which are related to macrophage activation and are critical to sarcoidosis inflammation, were decreased by the DNase1 treatment. Other cytokines including granulocyte colony-stimulating factor (G-CSF) and macrophage inflammatory proteins (MIP)-1β (also known as chemokine ligands 4, CCL4), involved in the stimulation and activation of granulocytes formation, were significantly decreased in the DNase1-treated mice. BAL neutrophils content was significantly lower in mice receiving DNase1 (0.06 x105), compared to mice receiving phosphate-buffered solution (4.51 x105). The neutrophil to leucocyte ratio was lower in DNase1 treated mice (0.08) when compared to vehicle treated mice (3.37).
The reduction in the number of granulomas and the average area as seen in hematoxylin and eosin slides paralleled these data. Finally, lower edema formation in the DNase1 treated mice (lung weight, lung index and protein content) was noted, further supporting that inhaled DNase1 in this animal model of sarcoidosis was able to suppress inflammation leading to granuloma formation.
In comparative nonclinical studies the equivalence of the biosimilar SM001 (Tigerase) and reference drug Pulmozyme has been demonstrated in terms of in vitro activity and toxicity (Amelina et al. 2019).