Panitumumab is a medication used in the treatment of cancer. It is a monoclonal antibody that targets and inhibits the epidermal growth factor receptor (EGFR), a protein that plays a role in the growth and spread of cancer cells. Panitumumab is primarily used in the treatment of metastatic colorectal cancer and certain other types of cancer that overexpress EGFR.

Panitumumab (Vectibix) is a fully human IgG2 monoclonal antibody that targets the EGFR (epidermal growth factor receptors).

Panitumumab Uses:

• Metastatic Colorectal Cancer:
  • Treatment of wild-type RAS (defined as wild-type in both KRAS and NRAS as determined by an approved test) metastatic colorectal carcinoma (mCRC), either as first-line therapy in combination with FOLFOX (fluorouracil, leucovorin, and oxaliplatin) or as a single agent therapy following disease progression after earlier treatment with fluoropyrimidine-, oxaliplatin-, and irinotecan-containing chemotherapy
• Limitations of use:
  • Panitumumab is not indicated for the treatment of patients with RAS-mutant metastatic colorectal carcinoma (mCRC) or for whom RAS mutation status is unknown.
• Off Label Use of Panitumumab in Adults:
  • metastatic colorectal cancer, KRAS wild-type (in combination with other chemotherapy agents)

Panitumumab Dose in Adults

• Note: Before starting treatment with panitumumab, a test needs to be done on the cancer cells. This test checks for something called RAS mutation. If the cells are "RAS wild-type," then the drug can be used. If they're not, then the drug might not be the right choice.

Panitumumab Dose in the treatment of metastatic colorectal cancer, RAS wild-type:

• For treating a certain type of advanced colon cancer (called "RAS wild-type"), panitumumab is given through an IV drip.
• The dose is 6 mg for every kilogram of the patient's weight, and it's given every 2 weeks.
• It can be given by itself or with another combination of drugs named FOLFOX.
• The treatment continues until the cancer gets worse or the side effects become too much to handle.

Panitumumab Dose in the treatment of metastatic colorectal cancer, RAS wild-type in combination with FOLFIRI (fluorouracil, leucovorin, and irinotecan; off-label combination): 

• For a certain type of advanced colon cancer (known as "RAS wild-type"), panitumumab can be combined with another drug mix called FOLFIRI.
• The patient gets 6 mg of panitumumab for every kilogram they weigh.
• This is given through an IV drip every 2 weeks.
• The treatment goes on until the cancer grows more or the side effects are too strong.

Use in children:

The safety and efficacy of the drug in children have not been established.

Panitumumab Pregnancy Risk Category: C

• Studies on animals suggest that panitumumab could harm an unborn baby if given to a pregnant woman.
• Panitumumab is a special type of antibody made to work like our body's own defense system.
• As pregnancy goes on, more of this antibody might pass to the baby.
• This is especially concerning since panitumumab stops a growth factor which is important for the baby's development.
• So, there's a risk it could affect the baby's growth.
• Because of this, women who can get pregnant should use birth control while taking this drug and continue for 2 months after their last dose.

Use panitumumab while breastfeeding

• We don't know if panitumumab gets into breast milk.
• This drug is a special type of antibody, and while some similar antibodies do get into breast milk, they usually don't end up in the baby's blood in big amounts.
• But, because there's a risk of harmful side effects for the baby, it's suggested that women don't breastfeed while taking this drug and for 2 months after the last dose.

Panitumumab Dose in Kidney Disease:

• The manufacturer hasn't given any special dosing instructions for people with kidney problems because it hasn't been studied yet.

Panitumumab Dose in Liver Disease:

• The manufacturer hasn't provided any special dosing guidance for people with liver issues because they haven't researched it yet.

Monotherapy:

Common Side Effects of Panitumumab (Vectibix):

• Central Nervous System:
  • Fatigue
• Dermatologic:
  • Skin Toxicity
  • Erythema
  • Pruritus
  • Acneiform Eruption
  • Paronychia
  • Rash
  • Skin Fissure
  • Exfoliative Dermatitis
  • Acne Vulgaris
• Endocrine & Metabolic:
  • Hypomagnesemia
• Gastrointestinal:
  • Nausea
  • Diarrhea
  • Vomiting
• Ophthalmic:
  • Ocular Toxicity
• Respiratory:
  • Dyspnea
  • Cough
• Miscellaneous:
  • Fever

Less Common Side Effects Of Panitumumab (Vectibix):

• Cardiovascular:
  • Pulmonary Embolism
• Central Nervous System:
  • Chills
• Dermatologic:
  • Nail Toxicity
  • Xeroderma
  • Desquamation
  • Dermal Ulcer
  • Pustular Rash
  • Papular Rash
• Endocrine & Metabolic:
  • Dehydration
• Gastrointestinal:
  • Mucositis
  • Stomatitis
  • Xerostomia
• Immunologic:
  • Antibody Formation
• Ophthalmic:
  • Abnormal Eyelash Growth
  • Conjunctivitis
• Respiratory:
  • Epistaxis
  • Interstitial Pulmonary Disease
• Miscellaneous:
  • Infusion Related Reaction

Combination Therapy With FOLFOX:

Common Side Effects Of Panitumumab (Vectibix):

• Dermatologic:
  • Skin Rash
  • Acneiform Eruption
  • Pruritus
  • Paronychia
  • Xeroderma
  • Erythema
  • Skin Fissure
  • Alopecia
  • Acne Vulgaris
• Endocrine & Metabolic:
  • Hypomagnesemia
  • Hypokalemia
  • Weight Loss
• Gastrointestinal:
  • Diarrhea
  • Anorexia
  • Abdominal Pain
  • Stomatitis
  • Mucosal Inflammation
• Neuromuscular & Skeletal:
  • Weakness
• Ophthalmic:
  • Conjunctivitis
• Respiratory:
  • Epistaxis

Less Common Side Effects Of Panitumumab (Vectibix):

• Cardiovascular:
  • Deep Vein Thrombosis
• Central Nervous System:
  • Fatigue
  • Paresthesia
• Dermatologic:
  • Nail Disorder
  • Palmar-Plantar Erythrodysesthesia
  • Cellulitis
• Endocrine & Metabolic:
  • Dehydration
  • Hypocalcemia
• Hypersensitivity:
  • Hypersensitivity
• Local:
  • Localized Infection

Contraindications to Panitumumab (Vectibix):

• In the U.S., the manufacturer doesn't list any specific situations where the drug shouldn't be used.
• But in Canada, they say not to use it if someone has had a very bad allergic reaction to panitumumab or any part of the drug before.

Warnings and precautions

Dermatologic toxicities: [US Boxed Warning]

• A strong warning about panitumumab is that it can cause skin problems.
• About 90% of people using it experienced skin issues, and for 15% of them, it was really severe.
• These issues can look like bad acne, itchy or red skin, dryness, cracked skin, or problems with nails.
• In rare cases, these skin issues got even more serious, leading to dangerous infections or rare skin diseases.
• If someone gets these severe skin problems, they might need to stop the treatment or take a lower dose.
• Interestingly, people with more severe skin reactions seemed to have better results from the drug.
• It's also important for patients to stay out of direct sunlight, use sunscreen, and wear protective clothing because the sun can make the skin reactions worse.

Diarrhea

• Panitumumab can cause diarrhea, especially when combined with other cancer drugs.
• This diarrhea can be very severe, leading to dehydration and even kidney problems.
• There have also been reports of stomach lining damage with the drug.

Depletion of electrolytes:

• Panitumumab can lower magnesium and calcium levels in the body during and even after treatment.
• This drop in levels can happen long after finishing the drug, sometimes 8 weeks or more.
• Patients might need supplements to bring these levels back up.
• It's important to check for low magnesium and calcium during and for at least 8 weeks after the treatment.
• Some people also had low potassium levels.

Infusion reactions

• Some people getting panitumumab have had serious reactions during the infusion, like trouble breathing, fever, chills, and low blood pressure.
• This happened to about 1% of patients, and in rare cases, it was deadly.
• If someone has a serious reaction, the infusion should be stopped right away and never given again if the severe reactions keep happening.

Ocular toxicities:

• Panitumumab can cause eye problems, including conditions that might lead to holes in the front part of the eye.
• If someone shows signs of these eye issues, they should be checked regularly.
• If the eye condition starts or gets worse, the treatment might need to be paused or stopped altogether.

Toxicity in the lungs:

• Panitumumab can sometimes cause lung problems.
• In rare cases, it has led to conditions where the lungs become scarred or inflamed, and some people have died from it.
• If someone starts having new or worse lung symptoms, the treatment should be paused.
• If it's confirmed they have a lung disease, the treatment should be stopped for good.

Status of RAS mutation and colorectal cancer:

• Before giving panitumumab for colorectal cancer, it's essential to test the cancer for certain RAS mutations.
• If these mutations are present, the drug likely won't help and could even be harmful.
• Panitumumab isn't for patients with positive RAS mutations or if we don't know their mutation status.
• Some studies showed that combining panitumumab with another treatment (FOLFOX4) made things worse for people with these mutations.
• The American Society of Clinical Oncology says that everyone with this kind of cancer who might get anti-EGFR drugs (like panitumumab) should be tested for RAS mutations in a special lab.
• Only patients without these mutations should consider this treatment.
• You can find information on the approved tests at the FDA's website.
• Also, panitumumab doesn't work well for people with another mutation called BRAF V600E.

Panitumumab: Drug Interaction

Note: Drug Interaction Categories:

• Risk Factor C: Monitor When Using Combination
• Risk Factor D: Consider Treatment Modification
• Risk Factor X: Avoid Concomitant Use

Monitoring Parameters:

• RAS Genotyping: Test the tumor to check if it has RAS mutations. Make sure it is RAS wild-type before starting the treatment.

Regular Checks During Treatment

• Electrolytes:
  • Check magnesium and calcium levels periodically during treatment and for at least 8 weeks after ending treatment.
  • Also, keep an eye on potassium levels.
• During Infusion:
  • Vital Signs: Check heart rate, blood pressure, and other vital signs.
  • Temperature: Monitor the patient's temperature before, during, and after the drug is given.
• Look Out For Side Effects:
  • Skin Issues: Watch for skin reactions.
  • Eye Issues: Check for any eye problems.
  • Lung Issues: Be alert for new or worsening breathing or lung problems.

How to administer Panitumumab (Vectibix)?

• Method: Only give through an IV drip. Don't push it in quickly or in a big burst.
• Equipment: Use a pump to control the drip. Use a special filter (0.2 or 0.22 micrometer) that doesn't bind much to proteins.
• Timing:
  • For doses up to 1,000 mg: Start with a 1-hour drip. If that goes well, the next times can be between 30 to 60 minutes.
  • For doses over 1,000 mg: Drip over 90 minutes.
• Preparation:
  • Use a saline solution (NS) to flush the IV line before and after the medicine.
  • Make sure not to mix with other drugs.
• If There's a Reaction:
  • For minor reactions: Slow down the drip by half.
  • For major reactions: Stop the drip. Think about not giving the drug again.
  • Always have the right medical tools and support on hand to handle any reactions.

Mechanism of action of Panitumumab (Vectibix):

• Panitumumab is a specially made protein that sticks to a specific part of cells called EGFR.
• When it attaches there, it stops other things like EGF from binding.
• This blocking action slows down or stops the cell from growing and changing.
• However, if the cells have certain mutations in them called RAS, this stopping action might not work.

Half-life elimination:

• Panitumumab takes about 7.5 days on average to reduce by half in the body.
• This can vary between 4 to 11 days.

International Brands of Panitumumab:

• Vectibix

Panitumumab Brand Names in Pakistan:

Not Available.