OYSIENDX (Osimertinib)

Osimertinib  is a medication used to treat non-small-cell lung carcinomas with specific mutations. It is a third-generation epidermal growth factor receptor tyrosine kinase inhibitor.

The most common side effects include diarrhea, rash, musculoskeletal pain, dry skin, skin inflammation around nails, sore mouth, fatigue and cough.

Osimertinib was approved for medical use in the United States in November 2015,and in the European Union in February 2016.

Osimertinib is used to treat locally advanced or metastatic non-small-cell lung cancer (NSCLC), if the cancer cells are positive for the T790M mutation in the gene coding for EGFR or for activating EGFR mutations. The T790M mutation may be de novo or acquired following first-line treatment with other tyrosine kinase inhibitors (TKIs), such as gefitinib and afatinib.

In the US, EGFR exon 19 deletions, exon 21 L858R mutations or the T790M status of the patient prior to treatment with osimertinib must be detected by a federally approved companion diagnostic test.The Food and Drug Administration (FDA) has approved FoundationOne CDx as one available companion diagnostic test for this purpose. In Europe and elsewhere, activating EGFR mutations or T790M mutations may be determined by a validated test.

In people treated with osimertinib, resistance usually develops within approximately 10 months.Resistance mediated by an exon 20 C797S mutation accounts for the majority of resistance cases.

It can cause fetal harm, so should not be used in women who are pregnant, and women who take it should avoid becoming pregnant.

Caution should be taken in people with a history of interstitial lung disease (ILD), as they were excluded from clinical trials, since the drug can cause severe ILD or pneumonitis. Caution should also be taken in people with a predisposition to long QT syndrome as the drug can provoke this.

Why is this medication prescribed?
Osimertinib is used to help prevent a certain type of non small-cell lung cancer (NSCLC) from returning after the tumor(s) has been removed by surgery in adults. It is also used as a first treatment for a certain type of NSCLC that has spread to other parts of the body in adults. Osimertinib is also used to treat certain types of NSCLC that has spread to other parts of the body in adults who could not be treated successfully with other similar chemotherapy medications. Osimertinib is in a class of medications called kinase inhibitors. It works by blocking the action of the abnormal protein that signals cancer cells to multiply. This helps stop or slow the spread of cancer cells and may help shrink tumors.

How should this medicine be used?
Osimertinib comes as a tablet to take by mouth. It is usually taken with or without food once a day. The length of your treatment depends on how well this medication works for you, and the side effects that you experience. Take osimertinib at around the same time every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take osimertinib exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

If you cannot swallow the tablets, place the tablet into 4 tablespoons (2 oz [60 mL]) of water and stir until the tablet is in small pieces. Drink the mixture right away. Pour in another half a cup (4 oz [120 mL]) to a cup of water (8 oz [240 mL]) to the container you used, rinse, and drink to make sure you get the full dose of osimertinib. Do not use carbonated water or any other liquid to dissolve the osimertinib tablet. Do not crush the tablet or heat the mixture. If you have a nasogastric (NG) tube, your doctor or pharmacist will explain how to give this mixture through an NG tube.

Your doctor may temporarily or permanently stop your treatment or decrease your dose of osimertinib depending on the side effects that you experience. Be sure to talk to your doctor about how you are feeling during your treatment. Do not stop taking osimertinib without talking to your doctor.

Ask your pharmacist or doctor for a copy of the manufacturer's information for the patient.

Other uses for this medicine
This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

What side effects can this medication cause?
Osimertinib may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:
diarrhea
constipation
rash
itching
dry or cracking skin
eczema
nausea
vomiting
loss of appetite
swelling or sores in the mouth
back pain
nail changes including swelling, redness, pain, splitting, breaking, and separation or loss from nailbed.