Dr. Sue Cancer Vet® has answered some of the questions we get most from pet parents who want to get their dog back to their normal self as soon as possible.
Dr. Sue Ettinger, also known as Dr. Sue Cancer Vet®, is a board-certified veterinary cancer specialist who has successfully used STELFONTA to treat many dogs’ mast cell tumors at her clinic in Connecticut.
If your question is not answered below, contact your veterinarian or Virbac on 1800-338-3659.
STELFONTA® (tigilanol tiglate injection) has been approved for the intratumoral treatment of all grades of non-metastatic mast cell tumors, providing the tumor is less than 10cm³, specifically:
STELFONTA should not be injected into subcutaneous mast cell tumors located above the elbow or hock (e.g. on the body, head, or neck) as necrotic debris from the injected tumor may accumulate under the skin, increasing the risk of systemic adverse reactions, including death, from mast cell degranulation.
STELFONTA is only approved for the treatment of mast cell tumors in dogs. The active ingredient in STELFONA (tigilanol tiglate) is currently under development for its potential to treat human cancers. It is important to note that the strength and formulation used in human development is different from STELFONTA.
In early 2024 the United States Food and Drug Administration (FDA) have awarded tigilanol tiglate Orphan Drug Designation (ODD) for the treatment of soft tissue sarcoma in humans. What does that mean? ODD is a special status awarded to drugs that are considered to have potential for patients with rare (‘orphan’) diseases and encouragingly, an important aspect of the application process for ODD was the safety and efficacy data gained during our clinical trials with dogs. However, any approval of a drug to treat soft tissue sarcoma will need to go through a rigorous human drug development process and FDA examination.
STELFONTA® (tigilanol tiglate injection) removes 87% of mast cell tumors after one or two treatments combined, and 75% after a single treatment.
STELFONTA is an injectable drug used to treat mast cell tumors locally. The active ingredient in STELFONTA is tigilanol tiglate, a substance that works by:
This results in tumor destruction, leaving a wound where the tumor once was.
Treatment with STELFONTA has been associated with cellulitis and severe tissue sloughing extending away from the treated site resulting in extensive wounds that require additional treatment and prolonged recovery times.
STELFONTA is a local mast cell tumor (MCT) treatment and does not prevent the development of new MCTs. Studies show 10-30% of dogs may develop a new MCT regardless of how the original tumor was treated. Check your dog every month for the presence of new lumps as early treatment will provide the best outcome for your dog
The active ingredient in STELFONTA is tigilanol tiglate, which was discovered in the Australian rainforest in 2005.
While the price of a STELFONTA injection varies depending on the size of the tumor, it is often comparable to the cost of surgery. You will need to discuss specific costs with your veterinarian. Make sure to ask if the quoted cost includes the consultation, post-injection checks and any medication your dog may need.
Your veterinarian will prescribe three essential medications (see chart below) to maximize STELFONTA treatment success and minimize potential severe adverse reactions. These medications include a corticosteroid, antihistamine and a gastrointestinal protectant. The corticosteroid must commence two days before the STELFONTA injection. Additionally, your veterinarian may prescribe pain medication during treatment. It is important that you give your dog all medication as prescribed to reduce risk of adverse reactions.
Download our helpful medication schedule to keep track of the days and times of administration:
Your dog should not receive their STELFONTA injection unless you have given them the corticosteroid in the two days before treatment day.
Following the STELFONTA injection, it is important to contact your veterinarian if you miss a dose of medication. Missing or modifying a dose may be harmful to your dog.
As STELFONTA destroys the mast cell tumor, the tumor shrivels up and falls away, leaving a wound where the tumor once was. Formation of a wound is an intended and likely response to treatment with STELFONTA, along with associated swelling and bruising; these wounds may be extensive and are expected to heal with minimal intervention. Your veterinarian may prescribe pain relief to keep your dog comfortable.
There are several factors that influence the size of the wound including the location and size of the tumor. In clinical studies, the average wound size at Day 7 for a STELFONTA treated dog was 1.3 in x 0.9 in. On Day 28, the average wound size had decreased to 0.8 in x 0.6 in. In some cases, a severe, larger than normal wound may develop, delaying wound healing. Intervention is not typically required, but occasionally the treating veterinarian may recommend applying a loose bandage or Elizabethan collar.
Within hours of STELFONTA treatment, bruising and swelling as well as heat and pain are expected.
These signs may increase within the first three days. While these may be considered a normal part of the treatment process, if the signs occur beyond the tumor site or your dog is showing other signs of illness such as vomiting, frequent diarrhea or lack of appetite, contact your veterinarian.
During the first week, the treated tumor site will become blackened. The skin over the surface of the tumor may break down and fluid may leak from the site. Swelling around the tumor may cause some discomfort to your dog. If necessary, talk to your veterinarian about pain medication, adjusting current pain medications or additional pain medication.
In the first one to two weeks as the tumor breaks down, there will be a pocket or wound where the tumor was located. Typically healing occurs within 4-6 weeks following STELFONTA treatment. During this time, healthy new skin will grow and close over the pocket or wound where the tumor was located.
Dogs respond differently depending on the size of the mast cell tumor treated, the nature of the dog, and how they react to accompanying medication.
During the first few days following treatment, your dog may experience bruising and/or swelling at the treatment site, and this may cause discomfort or pain. If this is the case, chat to your veterinarian about pain medication. Your dog may also seem lethargic and may have a decreased appetite, but this will typically resolve by day three or four when the tumor begins to disintegrate. By day seven, most dogs are back to normal.
Your vet will suggest a follow-up schedule to check your dog’s overall health during the treatment.
Contact your veterinarian if you are concerned or have questions regarding your dog’s behavior or symptoms following STELFONTA treatment.
Swelling and bruising around the treated tumor are common signs expected with STELFONTA treatment. The amount of swelling and bruising varies depending upon the size and location of the treated tumor and typically resolves 3 to 7 days after the injection. Discuss any concerns you have about the level of swelling or bruising with your veterinarian.
The treated site may have an odor for up to a week as the tumor breaks down and cancer cells are destroyed. Contact your veterinarian if you are concerned about the odor.
It is not uncommon for dogs to experience mild to moderate pain or discomfort at the tumor site for the first 1-4 days after treatment. If your veterinarian did not prescribe pain medication to commence once you get home on treatment day and your dog is showing signs of discomfort, discuss pain management options with your veterinarian.
The treated tumor site is typically left uncovered. Normally, you will not need to manage the wound following STELFONTA treatment. If the wound gets gritty or dirty, flush the area with a gentle shower stream; wear disposable gloves and immediately wash off any fluid that comes into contact with your skin.
Some discharge from the treated tumor site is expected as the tumor breaks down. The site can be cleaned with warm water, as necessary. Wear disposable gloves when cleaning the site. If your dog is excessively licking or rubbing the treated tumor site, contact your veterinarian who may recommend an Elizabethan collar (“e-collar”) or a loose bandage to cover the wound.
If another animal in the household is licking or grooming the treated tumor site, the animals should be separated to prevent trauma to the site.
Contact your veterinarian if you are concerned about the appearance of the wound or management of the treated site.
We expect some discharge from the treated tumor site as the tumor breaks down. You may clean the area with warm water but do not use soaps, shampoos or disinfectants on the wound. Wear disposable gloves when cleaning the site.
Contact your veterinarian if you are concerned about the appearance of the wound or management of the treated site.
If any other animal is likely to lick your dog’s wound, keep them separated to prevent trauma to the treated site as this may delay wound healing. No adverse events have been attributed to ingestion of the discharge or tumor remnants.
There is no need to bathe your dog following STELFONTA treatment, and you should avoid getting shampoo onto the treated area. If you choose to wash your dog, take care as they may have discomfort around the treated site. Let the area air dry if possible. It is usual for the treated tumor to have discharge; wear disposable gloves if it is necessary to touch the area until the discharge stops.
If the wound has not been bandaged, your dog can swim in clean, unpolluted water following STELFONTA treatment. Please consult your veterinarian for further information.
Your dog can exercise normally following STELFONTA treatment regardless of tumor location. Your dog may be less active for the first few days following treatment and may not want to exercise. After this period, your dog will generally return to regular activity and exercise.
Contact your veterinarian if you are concerned about your dog’s activity level.
Dogs often lick the treated area. However, if your dog licks or rubs the site excessively, ask your veterinarian whether an Elizabethan collar (“e-collar”) or bandage is indicated.
In some cases, the tumor may not resolve completely following a single STELFONTA treatment. Your veterinarian will be able to assess how your dog has responded once 28 days have passed and will be able to recommend the best course of action. STELFONTA removes 75% of tumors with a single injection and 87% with one or two injections combined.
STELFONTA may cause side effects, even at the prescribed dose. These side effects include, but are not limited to:
Your veterinarian will prescribe medications before and after treatment to minimize the chance of an abnormal degranulation reaction. These would include a corticosteroid, antihistamine, and an antacid. It is crucial your dog receives their medication exactly as prescribed to minimize the risk of degranulation. Monitor your dog for 5-7 days following treatment with STELFONTA for signs of a systemic reaction. Symptoms may include vomiting, diarrhea, lethargy, decreased appetite, abnormal breathing, collapse, hives, or excessive swelling or bruising at or away from the treated site. Contact your veterinarian as soon as possible; this is an emergency.
Contact your veterinarian if you have any concerns, are unable to give your dog the additional medications prescribed, or if you notice any of the following in your dog:
Treatment with STELFONTA has been associated with cellulitis and severe tissue sloughing extending away from the treated site resulting in extensive wounds that require additional treatment and prolonged recovery times.
STELFONTA is an irritant, and you should avoid accidental exposure to skin, eyes, or ingestion. If it touches your skin or eyes, repeatedly wash the area with water. If wearing contact lenses, rinse the eyes first, then remove contacts and continue to rinse with water. If symptoms such as local signs of redness and swelling occur, or if there has been ingestion, seek the advice of a physician and show them the package insert. You and your physician can contact Virbac at 1800.338.3659 (choosing the option for human exposure) for further information.
Safety concerning people who are pregnant or breastfeeding has not been assessed, so take standard precautions when handling the wound, including:
If you have questions related to STELFONTA treatment, discuss with your veterinarian.
To report a suspected adverse reaction (side effect) call Virbac at 1-800-338-3659.
Mast cell tumors are the most common type of skin cancer in dogs. Mast cells are found in most tissues and organs and are part of the immune system. Organs that come into contact with the outside world, such as skin and lungs, contain the highest levels of mast cells. If mast cells turn cancerous, a mast cell tumor forms and may range from benign to aggressive with a higher likelihood of spreading throughout the body.
Tumor stage and grade are used by veterinarians to determine the best course of treatment, based on how advanced the tumor already is and how rapidly it is likely to spread:
You’ve probably heard about the risks of mast cell degranulation, whereby mast cells release granules of substances such as histamine. Any handling of a mast cell tumor can lead to large numbers of granules being released leading to swelling, bruising, heat and pain at the tumor site. Dogs may also experience vomiting, diarrhea, lack of appetite, high blood pressure and even death from degranulation of these tumors. This is why it is imperative to give your dog their full dose of prescribed medicines both before and after STELFONTA treatment.
Your veterinarian will prescribe these essential medications to minimize the chance of an abnormal degranulation reaction. These include a corticosteroid which starts two days before STELFONTA treatment, an antihistamine, and an antacid. Contact your veterinarian immediately if your dog has not been given the medications as prescribed or if it shows signs of degranulation.
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