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.
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.
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.
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.
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. 4
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.
Adverse reactions (frequency and seriousness):
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.
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).5
Mild or moderate neutropenia with a mean duration of approximately 24 days.
ncrease 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
- common (more than 1 but less than 10 animals in 100 animals)
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
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
Amounts to be administered and administration route:
For oral use.
The recommended dose is 12.5 mg/kg (with a dose range of 11–14 mg/kg) once daily as presented in the table below.
In dogs with a bodyweight of less than 15 kg accurate dosing is not always possible. These dogs may be treated with either 50, 100 or 150 mg, if it is feasible to achieve a target dose of 11–14 mg/kg bw.
The tablets must be administered as a whole and should not be divided, broken or ground. If a broken tablet is rejected by the dog after chewing, it should be disposed of.
Tablets should always be administered in the same manner, with food. 6
12.5 mg/kg bw Number of tablets per day Dose mg/kg Dog body-weight in kg 50 mg 150 mg lower weight upper weight > 15 18 1 plus 1 13.7 11.1 > 18 22 2 plus 1 13.9 11.4 > 22 26 2 13.6 11.5 > 26 30 1 plus 2 13.5 11.7 > 30 34 2 plus 2 13.3 11.8 > 34 38 3 13.2 11.8 > 38 42 1 plus 3 13.2 11.9 > 42 46 2 plus 3 13.1 12.0 > 46 50 4 13.0 12.0 > 50 54 1 plus 4 13.0 12.0 > 54 58 2 plus 4 13.0 12.1 > 58 62 5 12.9 12.1 > 62 66 1 plus 5 12.9 12.1 > 66 70 2 plus 5 12.9 12.1 > 70 74 6 12.9 12.2 > 74 78 1 plus 6 12.8 12.2 > 78 2 plus 6 12.8 I
If the tablet is regurgitated or vomited within 10 minutes following administration, treatment should be repeated. If the tablet is regurgitated or vomited later than 10 minutes following administration, treatment should not be repeated.
The treatment should be reviewed after 4 to 6 weeks in order to assess the initial response. Duration of treatment depends on the response to treatment. Treatment should be maintained in the case of stable disease, i.e. static, partial or complete tumour response, provided that the product is sufficiently well tolerated. In case of tumour progression, treatment is unlikely to be successful and the treatment hould be reviewed.
Dose reduction, treatment interruption and treatment discontinuation:
Dogs should be monitored carefully and professional judgement should be used to determine the need for dose reduction in the event of possible significant adverse reactions (see section 4.5). Doses can be reduced to 9 mg/kg bodyweight (range 7.5–10.5 mg/kg) or 6 mg/kg bw (range 4.5–7.5 mg/kg)
according to the tables below.
During clinical studies, the daily dose was decreased due to adverse events in approximately 16 % of
treated dogs and mainly due to an increase in transaminases.7
9 mg per kg bodyweight once daily as presented in the table below.
Number of tablets per day Dose mg/kg
Dog body-weight in
50 mg 150 mg lower weight upper weight
> 15.0 19.4 1 10.0 7.7
> 19.4 25.0 1 plus 1 10.3 8.0
> 25.0 30.6 2 plus 1 10.0 8.2
> 30.6 36.1 2 9.8 8.3
> 36.1 41.7 1 plus 2 9.7 8.4
> 41.7 47.2 2 plus 2 9.6 8.5
> 47.2 52.8 3 9.5 8.5
> 52.8 58.3 1 plus 3 9.5 8.6
> 58.3 63.9 2 plus 3 9.4 8.6
> 63.9 69.4 4 9.4 8.6
> 69.4 75.0 1 plus 4 9.4 8.7
> 75.0 80.6 2 plus 4 9.3 8.7
6 mg per kg bodyweight once daily as presented in the table below.
Number of tablets per day Dose mg/kg
Dog body-weight in
50 mg 150 mg lower weight upper weight
> 15.0 20.8 2 6.6 4.8
> 20.8 29.2 1 7.2 5.1
> 29.2 37.5 1 plus 1 6.9 5.3
> 37.5 45.8 2 plus 1 6.7 5.5
> 45.8 54.2 2 6.5 5.5
> 54.2 62.5 1 plus 2 6.5 5.6
> 62.5 70.8 2 plus 2 6.4 5.6
> 70.8 79.2 3 6.4 5.7
> 79.2 1 plus 3 6.3
Overdose (symptoms, emergency procedures, antidotes), if necessary:
The recommended daily dose of 12.5 mg/kg body weight corresponds to the Maximum Tolerated Dose (MTD) that was derived from repeat dose toxicity studies in healthy Beagle dogs.
Overdosing signs were observed in toxicity studies conducted in healthy dogs, treated for 39 weeks at doses of around 2 times the recommended dose (25 mg masitinib), treated for 13 weeks and 4 weeks at doses of around 3 times the recommended dose (41.7 mg masitinib), and treated for 4 weeks at doses of around 10 times the recommended dose (125 mg masitinib). The main target organs of toxicity in dogs are the gastrointestinal tract, the haematopoetic system, the kidney and the liver.
In case of adverse events following overdose, treatment should be discontinued until resolution, and then resumed at the recommended therapeutic dose level.
Pharmacotherapeutic group: protein-tyrosine kinase inhibitor.
ATCvet code: QL01XE90.
Masitinib is a protein-tyrosine kinase inhibitor which, in vitro, potently and selectively inhibits the
mutated form, in the juxtamembrane (JM) region, of the c-kit receptor. It also inhibits the Platelet
Derived Growth Factor (PDGF) receptor and the Fibroblast Growth Factor Receptor (FGFR3).
In the pivotal clinical field study, dogs of various breeds, ranging in age from two to seventeen years,
were randomly treated with Masivet at a dose of 12.5 mg/kg or with a placebo. In dogs with nonresectable
mast cell tumours, Grade 2 or 3, expressing a mutated tyrosine kinase c-kit receptor,
treatment with Masivet showed a significantly longer Time-to-Tumour Progression (TTP) with a
median of 241 days as compared to 83 days for placebo. Response to treatment with masitinib was
expressed as stable disease; i.e. static, partial or complete response.
Masitinib treatment should only be used in dogs with non-resectable mast cell tumours, 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.
Following oral administration in dogs at a dose of 11.2 mg (±0.5 mg) per kg of bodyweight, masitinib
is rapidly absorbed and the time to maximal concentration (Tmax) is approximately 2 hours. The
elimination half-life (t½) is approximately 3–6 hours. Masitinib is approximately 93 % bound to
Masitinib is metabolised predominantly by N-dealkylation. Excretion takes place in the bile.
List of excipients:
Pig liver powder
Titanium dioxide (E171)
Sunset yellow (E110) aluminium lake.
Shelf life of the veterinary medicinal product as packaged for sale: 3 years. 9
Special precautions for storage:
Keep the bottle tightly closed.
Nature and composition of immediate packaging:
White HDPE bottle closed with a thermosealable film and covered by a child-resistant closure cap.
30 ml bottle containing 30 Masivet 50 mg film-coated tablets.
40 ml bottle containing 30 Masivet 50 mg film-coated tablets.
60 ml bottle containing 30 Masivet 150 mg film-coated tablets.
Special precautions for the disposal of unused veterinary medicinal product or waste materials derived from the use of such products:
Any unused veterinary medicinal product or waste materials derived from such veterinary medicinal products should be disposed of in accordance with local requirements.
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