COMPANION ANIMAL VIRUSES
In-Vitro Efficacy Testing
Feline Leukemia Virus (FeLV)
We have also tested RetroMAD1 together with conventional treatment on 200 cats infected with FeLV in Malaysia, Singapore and Brazil. In Brazil cases, significant improvement was seen in appetite and body condition. Additionally, cases with common FeLV-associated symptoms FURD and gingivitis also saw significant recovery of these symptoms over a 3-6 month period. Real time PCR analyses on blood samples saw an average 90.9% reduction in viral titres after the approximate 3-months treatment. Cases were certain abnormal haematological (RBC, WBC) and serum biochemistry (ALT, AST) readings also showed normalisation towards the normal reference ranges after treatment.
Average vet scores before treatment (-1d) and at multiple timepoints over the course of RetroMAD1 treatment show consistent recovery of common FeLV associated symptom gingivitis, towards an ideal score of zero (no gingivitis).
Average vet scores before treatment (-1d) and at multiple timepoints over the course of RetroMAD1 treatment show consistent recovery of common FeLV associated symptom Feline Upper Respiratory Disease (FURD), towards an ideal score of zero (no FURD).
Feline Immunodeficiency Virus (FIV)
RetroMAD1 has been tested on approximately 71 FIV cases in Malaysia and Singapore. While there appears to be an improvement in appetite and weight after RetroMAD1 treatment, more data will be required to demonstrate statistical significance in the recovery of clinical symptoms as well reduction of viral tires. RetroMAD1 is expected to show similar promising outcomes as with FeLV given how closely related these two viruses are.
Feline Infectious Peritonitis (FIPV)
In Malaysia, 43 cats with the wet form of FIPV and 23 cats with the dry form of FIPV were treated with RetroMAD1 over a period of 3 months (median age 13 months). With conventional treatment, according to the Merck Veterinary Manual, median survival duration after FIPV diagnosis is just 9 days for wet form. For dry form this is 38 days.
While no significant differences to survival rate was noted, we observed that RetroMAD1 treatment used alongside conventional treatment greatly prolonged the survival duration of FIPV-infected cats. With RetroMAD1 treatment, 30% of dry form cases survived an average of 212 days, while 15% wet form cases survived an average of 236 days. Calculation of these averages were based on a fixed 1-year trial period after which case monitoring was discontinued, suggesting that it is likely that these averages may be higher.
Real time PCR analyses on collected blood/faeces samples saw an average 99.13% reduction in viral titres after the approximate 3-months treatment.
Canine Parvovirus 2 (CPV2)
We have tested RetroMAD1 together with conventional treatment on over 200 dogs infected with CPV2 between March 2010 and March 2015 in Malaysia and Philippines. The average survival rate determined was approximately 80%, as compared to only about 55-60% survival without RetroMAD1. Within a week of treatment, it was observed that these cases made significant improvement in terms of both physiological and behavioural parameters, as well as clinical symptoms. These parameters included body condition, grooming activity, appetite, behavioural condition, hypersalivation, stool condition, and vomiting.
Real time PCR analyses on collected faeces samples saw an average 94.75% reduction in viral titres after the approximate 7-day treatment.
Average vet scores before treatment (-1d) and after approximately 7-days of RetroMAD1 treatment show consistent recovery of common CPV2 symptoms towards an ideal score of zero (no symptom).
Feline Panleukopenia Virus (FPV)
As the feline counterpart of CPV2, we have also tested RetroMAD1 together with conventional treatment on 36 cats infected with FPV in Malaysia. Survival rates ranged between 61.9% and 86.9% after approximately 1-week. In contrast, published studies using conventional treatment alone have shown the average survival rate to be only approximately 51.1%. Significant recovery of clinical symptoms such as diarrhea, vomiting and fever were observed as well after approximately 7-days of RetroMAD1 treatment.
Average vet scores before treatment (-1d) and after (7 days) of RetroMAD1 treatment show significant recovery of common FPV symptoms towards an ideal score of zero (no symptom).
Numerous toxicology studies have been conducted to ensure RetroMAD1 is safe to use in cats and dogs. Acute and subchronic studies were done in multiple animal models with observations, complete blood counts, serum biochemistry and histology. Acute studies in rodents indicate that RetroMAD1 is safe up to 250 times the therapeutic dosage used in cats while subchronic studies in cats show no adverse effects after 3-months administration at 12 times the cat therapeutic dose.
Pharmacokinetic studies were conducted in multiple animal models to determine what happens to administered RetroMAD1 in the body. The concentration of RetroMAD1 was determined in various organs at different timepoints following administration at t=0.
Results show that within 30 minutes of administration RetroMAD1 passes through the stomach, intestine and appears in the liver and even serum. Rapid absorption allows it to peak in serum in 2 hours. pK profiles at t=24, 48 and 72, following a 2nd, 3rd and 4th administration at t=23.5, 47.5 and 72.5 respectively show similar profiles to that at t=0.5, after the 1st administration. This indicates that no residual RetroMAD1 remained from the 1st administration during subsequent administrations, i.e RetroMAD1 is fully excreted within 24 hours of administration (no bioaccumulation).
Serum pK via oral and subcutaneous routes of administration allowed determination of the relative bioavailability. Bioavailability is the proportion of administered drug that manages to reach the systemic circulation (blood) to achieve its therapeutic effect. The relative bioavailability of RetroMAD1 in rats was 10.4% and 39.1% in monkeys. In contrast, most orally administered peptides have very low bioavailabilities (less than 2%) and also short half-lives.
A preliminary immunogenicity studies in cats was conducted to assess the formation of anti-drug antibodies (ADA) with frequent RetroMAD1 administration. Healthy cats were fed with various dosages (up to 4x cat dose) of RetroMAD1 daily for 10 weeks with weekly assessment of antibody levels. While significant IgG-type antibody increases were found in 6 out of the 16 treated cats (37.5%), only 1 of them (6.25%) showed a typical immune response profile. This suggests that RetroMAD1 is weakly immunogenic. Additional studies are required to determine what proportion of these ADAs are neutralisation antibodies.