Rytelo

Pronunciation: ri-TEL-o
Generic name: imetelstat
Dosage form: injection for intravenous infusion

Medically reviewed by Carmen Pope, BPharm. Last updated on Jun 10, 2024.

What is Rytelo?

Rytelo (imetelstat) is an injectable telomerase inhibitor that may be used to treat low- to intermediate-1 risk myelodysplastic syndromes (MDS) in adults with anemia who require blood transfusions of 4 or more red blood cell units over 8 weeks AND who have not responded to, stopped responding to, or cannot be treated with other medicines called erythropoiesis-stimulating agents (ESA).

Rytelo is an oligonucleotide telomerase inhibitor that works by binding to and inhibiting the activity of an enzyme telomerase which prevents telomere binding. Treatment with Rytelo reduces telomere length, the number of malignant stem and progenitor cells, and causes cell death.

Myelodysplastic syndromes are a group of disorders caused by the malfunctioning of stem cells in the bone marrow. Insufficient red blood cell production causes anemia that can require regular blood transfusions.

Rytelo was FDA-approved on 6 June, 2024.

Rytelo side effects

The most common side effects of Rytelo affecting more than 10% of people taking it include:

decreased platelet counts
decreased white blood cell counts, including decreased neutrophils
increased liver enzymes (AST, alkaline phosphatase, and ALT)
fatigue/tiredness
longer than usual blood clotting times
joint, bone, and muscle pain
Covid-19 infections
headache.

Rytelo may cause fertility problems in females. This could affect your ability to get pregnant. Talk to your healthcare provider if this is a concern for you.

Serious side effects and warnings

Rytelo may cause serious side effects, including:

Low platelet counts (thrombocytopenia). These are common during treatment with Rytelo and can also be severe and increase your risk for bleeding. Your healthcare provider may give you platelet transfusions to reduce the risk of bleeding if you develop a low platelet count during treatment. Tell your healthcare provider right away if you develop any signs or symptoms of bleeding, including:

unusual bleeding or bruising
bleeding that lasts a long time
nosebleeds
vomiting blood
blood in your stools or black tarry stools.

Low neutrophil counts (neutropenia). These are a type of white blood cell and low neutrophil counts can be common and severe. They can increase your risk for infections, including serious infections and sepsis. Your healthcare provider may give you medicines before you start treatment to help prevent neutropenia and infections and may treat you with medicines if you develop these problems during treatment with Rytelo. Tell your healthcare provider right away if you develop any signs or symptoms of infection during treatment, including:

fever
shortness of breath or trouble breathing
cough
chills
pain or burning when you urinate.
- Your healthcare provider will do blood tests to check your platelet and neutrophil counts before starting treatment with Rytelo, weekly for the first 2 cycles of treatment before you receive each additional cycle, and as needed during your treatment.
- Your healthcare provider may delay your next treatment, decrease your dose, or stop treatment if you develop thrombocytopenia or neutropenia during treatment.

Infusion-related reactions that can be severe and may cause a sudden increase in blood pressure, called a hypertensive crisis. Your healthcare provider will give you medicines before each infusion to help prevent or lessen infusion-related reactions and will watch you for at least 1 hour after your infusion. If you develop infusion-related reactions, your healthcare provider may infuse Rytelo more slowly, temporarily stop, or permanently stop your treatment. Tell your healthcare provider if you develop any signs or symptoms of infusion-related reactions, including:

stomach pain
joint pain
weakness and tiredness
back and bone pain
diarrhea
redness
headache
high blood pressure
not feeling well
chest pain that is not related to your heart
itching
hives.

May cause harm to an unborn baby. Females of reproductive potential should use effective contraception.

It is not known if Rytelo is safe and effective in children.

These are not all of the possible side effects of Rytelo. Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Before taking

Before receiving Rytelo, tell your healthcare provider about all of your medical conditions, including if you:

are pregnant or plan to become pregnant
are breastfeeding or plan to breastfeed

Pregnancy

Rytelo may harm your unborn baby and may cause loss of pregnancy (miscarriage). Tell your healthcare provider right away if you become pregnant or think you may be pregnant during treatment.

Females who can become pregnant:

your healthcare provider will perform a pregnancy test before you are given Rytelo.
you should use effective birth control (contraception) during treatment with Rytelo and for 1 week after your last dose.

Breastfeeding

It is not known if Rytelo passes into breast milk. Do not breastfeed during treatment with Rytelo and for 1 week after your last dose.

How will I receive Rytelo?

Your healthcare provider gives Rytelo as an intravenous infusion into your vein over 2 hours.

It is usually given every 4 weeks.
The dosage depends on your weight but is calculated at 7.1 mg/kg. Your healthcare provider will prescribe a dose that is right for you and may change your dose or dosing schedule depending on how you respond.

Before treatment, your healthcare provider will administer the following pretreatment medications to prevent or reduce potential infusion-related reactions and will monitor you for at least 1 hour after the infusion for side effects.

An antihistamine such as diphenhydramine 25 mg to 50 mg, intravenously or orally
A corticosteroid such as hydrocortisone (or equivalent) 100 mg to 200 mg, intravenously or orally

During treatment, your healthcare provider will do certain blood tests to check for side effects and response.

How long you stay on treatment depends on how well you tolerate Rytelo and how effectively you respond to it. It is recommended that Rytelo be discontinued if you do not experience a decrease in the need for red blood cells (RBC) transfusion after 24 weeks of treatment (6 doses) or if unacceptable toxicity occurs.

What other drugs will affect Rytelo?

Tell your healthcare provider about all your medicines, including prescription and over-the-counter medicines, vitamins, and herbal supplements. Know the medicines you take. Keep a list to show your healthcare provider and pharmacist when you get a new medicine.

There are no specific drug-drug interactions listed in the Rytelo package insert, however, drug interaction studies have found Rytelo is:

not an inhibitor or inducer of CYP450 enzymes
an inhibitor of OATP1B1 and OATP1B3.

Refer to the latest package insert for more information about drug interactions.

Ingredients

Needs reconstitution and dilution before use. Does not contain a preservative.

Rytelo 47 mg dose:

Active ingredients: 47 mg of imetelstat (equivalent to 50 mg imetelstat sodium).

Inactive ingredients: sodium carbonate anhydrous or hydrochloric acid may be added during manufacturing to adjust the pH.

Rytelo 188 mg dose:

Active ingredients:188 mg of imetelstat (equivalent to 200 mg imetelstat sodium).

Inactive ingredients: sodium carbonate monohydrate or hydrochloric acid may be added during manufacturing to adjust the pH.

Storage

Store vials refrigerated at 2°C to 8°C (36°F to 46°F) in original carton. Do not freeze.

Once diluted, preferably use immediately, or within:

18 hours from the time of reconstitution when stored at room temperature 20°C to 25°C (68°F to 77°F):
48 hours from the time of reconstitution when stored refrigerated at 2°C to 8°C (36°F to 46°F)