Imetelstat (Rytelo™)

Imetelstat is a telomerase inhibitor. Telomerase inhibitors work by targeting the telomerase enzyme to stop uncontrolled cell division and do not grow. This is helpful in treating conditions like myelodysplastic syndrome (MDS). 

How To Take Imetelstat

Imetelstat is given intravenously (into a vein). The amount given and schedule are based on your size. You will have your labs checked before each dose. The results of your labs help guide your treatment plan. You will be given diphenhydramine (Benadryl) and hydrocortisone (steroid) before your infusion to help lessen an infusion-related reaction to the medication. Often, you will need to stay after your infusion is done to make sure you are not having a reaction.

Possible Side Effects of Imetelstat

 There are many things you can do to manage the side effects of imetelstat. Talk to your care team about these recommendations. They can help you decide what will work best for you. These are some of the most common or important side effects:

Low White Blood Cell Count (Leukopenia or Neutropenia) 

White blood cells (WBC) are important for fighting infection. While receiving treatment, your WBC count can drop, putting you at a higher risk of getting an infection. You should let your doctor or nurse know right away if you have a fever (temperature greater than 100.4°F/38°C), sore throat or cold, shortness of breath, cough, burning with urination, or a sore that doesn't heal. This medication can cause a rare complication called neutropenic colitis, which is a serious infection of the bowel. If you have abdominal pain, contact your care team immediately.

Tips to preventing infection:

• Washing hands, both yours and your visitors, is the best way to prevent the spread of infection.
• Avoid large crowds and people who are sick (i.e.: those who have a cold, fever or cough or live with someone with these symptoms).
• When working in your yard, wear protective clothing including long pants and gloves.
• Do not handle pet waste.
• Keep all cuts or scratches clean.
• Shower or bathe daily and perform frequent mouth care.
• Do not cut cuticles or ingrown nails. You may wear nail polish, but not fake nails.
• Ask your oncology care team before scheduling dental appointments or procedures.
• Ask your oncology care team before you, or someone you live with has any vaccinations.

Low Platelet Count (Thrombocytopenia) 

Platelets help your blood clot, so when the count is low you are at a higher risk of bleeding. Let your oncology care team know if you have any excess bruising or bleeding, including nose bleeds, bleeding gums or blood in your urine or stool. If the platelet count becomes too low, you may receive a transfusion of platelets.

• Do not use a razor (an electric razor is fine).
• Avoid contact sports and activities that can result in injury or bleeding.
• Do not take aspirin (salicylic acid), non-steroidal, anti-inflammatory medications (NSAIDs) such as Motrin/Advil (ibuprofen), Aleve (naproxen), Celebrex (celecoxib) etc. as these can all increase the risk of bleeding. Please consult with your healthcare team regarding use of these agents and all over-the-counter medications/supplements while on therapy.
• Do not floss or use toothpicks and use a soft-bristle toothbrush to brush your teeth.

Liver Toxicity

Imetelstat can cause liver toxicity, which your oncology care team may monitor for using blood tests called liver function tests. Notify your healthcare provider if you notice yellowing of the skin or eyes, your urine appears dark or brown, or you have pain in your abdomen, as these can be signs of liver toxicity.

Fatigue 

Fatigue is very common during cancer treatment and is an overwhelming feeling of exhaustion that is not usually relieved by rest. While on cancer treatment, and for a period after, you may need to adjust your schedule to manage fatigue. Plan times to rest during the day and conserve energy for more important activities. Exercise can help combat fatigue; a simple daily walk with a friend can help. Talk to your healthcare team for helpful tips on dealing with this side effect.

Joint or Muscle Pain

This medication can cause joint (arthralgia) or muscle (myalgia) aches and pains, which may be treated with medications. Talk with your care team about which pain relievers you can safely take. Non-medical therapies, such as acupuncture, yoga, gentle stretching, and exercise may also help reduce this side effect.

Important but Less Common Side Effects

• Infusion-Related Reactions: Infusion-related reactions could include changes in blood pressure or headaches. You will receive medications before the infusion to help prevent these reactions. Tell your care team right away if you notice any of these symptoms, as they may need to slow or stop the infusion. 

Reproductive Concerns

Exposure of an unborn child to this medication could cause birth defects, so you should not become pregnant or father a child while on this medication. Effective birth control is necessary during treatment and for at least 1 week after treatment. Even if your menstrual cycle stops or you believe you are not producing sperm, you could still be fertile and conceive. You should consult with your healthcare team before breastfeeding while receiving this medication.