4.1 Target species
Dogs.
4.2 Indications for use, specifying the target species
Treatment of non-resectable dog mast cell tumours (Grade 2 or 3) with confirmed mutated c-kit
tyrosine kinase receptor.
4.3 Contraindications
Do not use in pregnant or lactating bitches (see section 4.7).
Do not use in dogs less than 6 months of age or less than 4 kg body weight.
Do not use in dogs suffering from liver impairment, defined as AST or ALT > 3 x Upper Limit of
Normal (ULN). Do not use in dogs suffering from renal function impairment, defined as Urinary
Protein Creatinine (UPC) ratio > 2 or albumin < 1 x Lower Limit of Normal (LLN).
Do not use in dogs with anaemia (haemoglobin < 10 g/dl).
Do not use in dogs with neutropenia defined as absolute neutrophil count < 2,000 /mm3
.
Do not use in case of hypersensitivity to the active substance or to any of the excipients.
4.4 Special warnings
For any mast cell tumour treatable by surgery, surgery should be the first choice of treatment.
Masitinib treatment should only be used in dogs with non-resectable mast cell tumours and which
express the mutated c-kit tyrosine kinase receptor. The presence of a mutated tyrosine kinase c-kit
receptor must be confirmed prior to treatment (see also section 5.1).
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4.5 Special precautions for use
Special precautions for use in animals
Dogs should be carefully monitored and treatment might need to be adjusted or discontinued, if
necessary.
Monitoring of renal function
Renal function should be adequately monitored every month using dipstick urine testing.
In case of positive semiquantitative dipstick results (protein > 30 mg/dl), urinalysis should be
performed to determine urinary protein creatinine (UPC) ratio, and a blood sample to measure
creatinine, albumin and BUN.
If UPC ratio > 2, or creatinine > 1.5 upper limit of normal (ULN), or albumin < 0.75 lower limit of
normal (LLN) or blood urea nitrogen (BUN) > 1.5 ULN, discontinue treatment.
Monitoring of Protein loss syndrome
Perform every month a dipstick urine test. In case of positive semi-quantitative dipstick results
(protein ≥ 30 mg/dl), perform urinalysis to determine urinary protein creatinine (UPC) ratio.
Perform every month a blood measurement of albumin.
In case of UPC ratio > 2 or albumin < 0.75 lower limit of normal (LLN), treatment should be
interrupted until albumin and UPC values have returned to limit value (UPC ratio < 2 and
albumin > 0.75 LLN), treatment can then be continued at the same dose.
If of one of these events (UPC ratio > 2 or albumin < 0.75 LLN) occurs for a second time,
treatment should be permanently discontinued.
Anaemia and/or haemolysis
Dogs should be carefully monitored for signs of (haemolytic) anaemia. In case of clinical signs of
anaemia or haemolysis, haemoglobin, free bilirubin and haptoglobin should be measured and blood
cell counts (including reticulocyte) should be performed.
Treatment should be discontinued in case of:
Haemolytic anaemia, i.e. haemoglobin < 10 g/dl and haemolysis,
i.e. free bilirubin > 1.5 ULN and haptoglobin < 0.1 g/dl,
Anaemia due to lack of regeneration, i.e. haemoglobin< 10 g/dl and
reticulocytes < 80,000/mm3
.
Hepatic toxicity (ALT or AST elevation), neutropenia
In case of an increase of ALT or AST > 3 ULN, decrease of neutrophil count < 2,000/mm3
or any
other severe adverse events, treatment should be modified as follows:
At the first occurrence, treatment should be interrupted until resolution, and then resumed at the same
dose level;
At the second occurrence of the same event, treatment should be interrupted until resolution; treatment
should then be continued with a reduced dose of 9 mg/kg bodyweight/day;
At the third occurrence of the same event, treatment should be interrupted until resolution; treatment
should then be continued with a dose further reduced to 6 mg/kg/day;
Treatment should be discontinued, if severe adverse reactions are still encountered at the 6 mg/kg/day
dose.
Other precautions
Treatment should be permanently discontinued in case of renal toxicity, immune-mediated haemolytic
anaemia (IMHA) and/or anaemia due to lack of regeneration, and if severe neutropenia, and/or severe
diarrhoea and/or severe vomiting persist after dose reduction.
Dogs should not be used for breeding while under treatment.
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Summary of thresholds for laboratory evaluations resulting in contra-indication or
treatment modification (interruption, dose reduction or discontinuation)
Management of Hepatic Toxicity (ALT or AST)
Contra-indication Interruption Dose reduction Discontinuation
> 3 ULN > 3ULN
(1st time)
> 3 ULN
(2nd/3rd time)
> 3ULN
(4th time)
Management of Neutropenia (neutrophil counts)
Contra-indication Interruption Dose reduction Discontinuation
< 2,000/mm3 < 2,000/mm3
(1st time)
< 2,000/mm3
(2nd/3rd time)
< 2,000/mm3
(4th time)
Management of Protein-Loss Syndrome (Albuminemia and/or UPC)
Contra-indication Interruption Dose reduction Discontinuation
Albumin < 1 LLN
or UPC > 2
Albumin < 0.75 LLN
or UPC >2
(1st time)
Not applicable Albumin < 0.75 LLN
or UPC > 2
(2nd time)
Management of Haemolytic and aregenerative Anaemia
(haemoglobin, bilirubin, haptoglobin, reticulocytes)
Contra-indication Interruption Dose reduction Discontinuation
Haemoglobin
< 10 g/dL
Not applicable Not applicable Haemoglobin < 10 g/dl
and either
free bilirubin > 1.5 ULN and
haptoglobin < 0.1 g/dl
or reticulocytes < 80,000/mm3
Special precautions to be taken by the person administering the veterinary medicinal product to
animals
Repeated dermal contact with masitinib may impair female fertility and foetal development.
The active substance of Masivet can cause skin sensitisation.
• Avoid skin contact with faeces, urine, and vomit of treated dogs.
• Wear protective gloves while disposing of vomit, urine or faeces of treated dogs.
• If broken tablets, vomit, urine or faeces of treated dogs come into contact with the skin, rinse
immediately with plenty of water.
The active substance of Masivet can cause severe eye-irritation and serious damage to the eyes.
• Avoid contact with the eyes.
• Take care not to touch the eyes before gloves have been removed and disposed of and the
hands have been thoroughly washed.
• If the product comes into contact with the eyes, rinse immediately with plenty of water.
People with known hypersensitivity to masitinib should not handle the product.
In case of accidental ingestion, seek medical advice immediately and show the package leaflet or the
label to the physician. Do not eat, drink, or smoke when treating the dog.
Children should not have close contact to treated dogs, treated dog faeces or vomit.
4.6 Adverse reactions (frequency and seriousness)
Very common
Mild to moderate gastrointestinal reactions (diarrhoea and vomiting) with a mean duration of
approximately 21 and 9 days, respectively.
Mild to moderate alopecia with a mean duration of approximately 26 days.
Common
Severe renal toxicity may occur in dogs suffering from renal disorders at the start of treatment
(including high blood creatinine level or proteinuria).
Moderate to severe anaemia (aplastic/haemolytic) with a mean duration of approximately 7 days.
Protein-loss syndrome (mainly due to a decrease in serum albumin).
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Mild or moderate neutropenia with a mean duration of approximately 24 days.
Increase in aminotransferase (ALT or AST) with a mean duration of approximately 29 days.
Specific measures to be taken in case of the above reactions are described in section 4.5.
Other commonly observed adverse reactions were in most cases mild or moderate:
Lethargy and asthenia with a mean duration of approximately 8 and 40 days, respectively.
Decrease in appetite or anorexia with a mean duration of 45 days and 18 days, respectively.
Cough (mean duration 23 days).
Lymphadenopathy (mean duration 47 days).
Oedema (mean duration of oedema was 7 days).
Lipoma (mean duration 53 days).
The frequency of adverse reactions is defined using the following convention:
- very common (more than 1 in 10 animals displaying adverse reaction(s) during the course of
one treatment)
- common (more than 1 but less than 10 animals in 100 animals)
4.7 Use during pregnancy, lactation or lay
Do not use in pregnant or lactating bitches. Laboratory studies in rats have shown evidence of
impaired female fertility at dose of 100 mg/kg/day, embryotoxicity and developmental toxicity at dose
above 30 mg/kg/day. Studies in rabbits did however not reveal embryotoxicity or developmental
toxicity.
4.8 Interaction with other medicinal products and other forms of interaction
In vitro tests with human microsomes demonstrate that concomitant treatment with substances which
are metabolised by CYP450 isoforms may result in higher or lower plasma levels of either masitinib or
those substances. No corresponding information is available for dogs. Hence, caution is advised with
the concurrent use of masitinib and other substances.
Concurrent use of other substances with a high degree of protein binding may compete with masitinib
binding and thus cause adverse effects.
The efficacy of Masivet might be reduced in dogs previously treated with chemotherapy and/or
radiotherapy. No information relating to potential cross-resistance with other cytostatic products is
available.