Pralsetinib – Uses, Dosage, Side Effects, Interaction

Pralsetinib is an orally bioavailable selective inhibitor of mutant forms of and fusion products involving the proto-oncogene receptor tyrosine kinase RET, with potential antineoplastic activity. Upon administration, pralsetinib binds to and targets various RET mutants and RET-containing fusion products. RET gene mutations and translocations result in the upregulation and/or activation of RET tyrosine kinase activity in various cancer cell types; dysregulation of RET activity plays a key role in the development and regression of these cancers.

Pralsetinib, similar to the previously approved selpercatinib, is a kinase inhibitor with enhanced specificity for RET tyrosine kinase receptors (RTKs) over other RTK classes. Enhanced RET (Rearranged during transfection) oncogene expression is a hallmark of many cancers, including non-small cell lung cancer. Although multikinase inhibitors, including cabozantinibponatinibsorafenibsunitinib, and vandetanib, have shown efficacy in RET-driven cancers, their lack of specificity is generally associated with substantial toxicity. Pralsetinib (BLU-667) and selpercatinib (LOXO-292) represent the first generation of specific RET RTK inhibitors for the treatment of RET-driven cancers.[rx]

Although a phase 1/2 trial of pralsetinib termed ARROW (NCT03037385) is still ongoing, pralsetinib was granted accelerated FDA approval on September 4, 2020, for the treatment of metastatic RET-fusion positive non-small cell lung cancer. It is currently marketed under the brand name GAVRETO™ by Blueprint Medicines.

Mechanism of action

Rearranged during transfection (RET) is a transmembrane receptor tyrosine kinase containing extracellular, transmembrane, and intracellular domains whose activity is required for normal kidney and nervous system development. Constitutive RET activation is achieved through chromosomal rearrangements producing 5′ fusions of dimerizable domains to the 3′ RET tyrosine kinase domain leading to constitutive dimerization and subsequent autophosphorylation; the most common fusions are KIF5B-RET and CCDC6-RET, although more than 35 genes have been reported to fuse with RET. Constitutive activation leads to increased downstream signalling and is associated with tumour invasion, migration, and proliferation.[rx]

Pralsetinib (formerly referred to as BLU-667) was developed through screening more than 10,000 agnostically designed kinase inhibitors followed by extensive chemical modification to improve its properties. Pralsetinib displays in vitro IC50 values for both WT RET as well as several mutant forms, including CCDC6-RET, in the range of 0.3-0.4 nmol/L, and is 100-fold more selective for RET kinase over 96% of 371 kinases tested.5 It is this specific inhibition of RET kinase that is associated with anti-tumour activity and clinical benefit in patients.

Despite increased selectivity for RET over other kinases, pralsetinib has been reported to inhibit DDR1, TRKC, FLT3, JAK1-2, TRKA, VEGFR2, PDGFRb, and FGFR1-2 at clinically relevant concentrations. The significance of these findings remains uncertain.[rx]

Pralsetinib exerts an anti-tumour effect through specific inhibition of the rearranged during transfection (RET) tyrosine kinase, including multiple distinct oncogenic RET fusions, mutated RET kinase domains harbouring gatekeeper mutations, and in RET kinases with a variety of activating single point mutations. Due to pralsetinib’s high selectivity for RET over other kinases, both in vitro and in vivo,[rx] pralsetinib has been described as having a better safety profile compared to previously used multi-kinase inhibitors. Despite this, pralsetinib use may increase the risk of hypertension, hemorrhagic events, impaired wound healing, hepatotoxicity, interstitial lung disease/pneumonitis, and embryo-fetal toxicity.[rx]

Indications

  • Treatment of lung cancer (small cell and non-small cell lung cancer )
  • Pralsetinib is a RET receptor tyrosine kinase inhibitor for the treatment of metastatic RET-driven non-small cell lung cancer.
  • Gavreto is indicated as monotherapy for the treatment of adult patients with rearranged during transfection (RET) fusion-positive advanced non-small cell lung cancer (NSCLC) not previously treated with a RET inhibitor.
  • Treatment of thyroid cancer
  • Pralsetinib is approved to treat: Medullary thyroid cancer that has a mutation in the RETgene and is advanced or metastatic. It is used in adults and children aged 12 years and older who need systemic therapy. Non-small cell lung cancer has a RET fusion gene and is metastatic. It is used in adults. Thyroid cancer that has a RET fusion gene and is metastatic or advanced. It is used in adults and children aged 12 years and older who need systemic therapy, including those who received radioactive iodine and it did not work or is no longer working.
  • Pralsetinib is indicated for the treatment of metastatic non-small cell lung cancer (NSCLC) in adult patients who are confirmed to possess a rearranged during transfection (RET) gene fusion, as determined by an FDA approved test. It is also indicated in adult and pediatric patients 12 years of age and older for the treatment of advanced or metastatic RET-mutant medullary thyroid cancer, and in this same population for the treatment of advanced or metastatic RET fusion-positive thyroid cancer who require systemic therapy and for whom radioactive iodine is not appropriate.[rx]
  • Advanced RET-fusion Non Small Cell Lung Cancer
  • Advanced RET-fusion thyroid cancer
  • Advanced RET-mutant medullary thyroid cancer
  • Metastatic RET-fusion Non Small Cell Lung Cancer
  • Metastatic RET-fusion thyroid cancer
  • Metastatic RET-mutant medullary thyroid cancer

Use in Cancer

Pralsetinib is approved to treat:

  • Medullary thyroid cancer has a mutation in the RET gene and is advanced or metastatic. It is used in adults and children aged 12 years and older who need systemic therapy.
  • Non-small cell lung cancer has a RET fusion gene and is metastatic. It is used in adults.
  • Thyroid cancer that has a RET fusion gene and is metastatic or advanced. It is used in adults and children aged 12 years and older who need systemic therapy, including those who received radioactive iodine and it did not work or is no longer working.

¹This use is approved under FDA’s Accelerated Approval Program. As a condition of approval, confirmatory trial(s) must show that pralsetinib provides a clinical benefit in these patients.

Pralsetinib is also being studied in the treatment of other types of cancer.

Contraindications

  • high blood pressure
  • bleeding
  • recent operation
  • abnormal liver function tests
  • impaired wound healing
  • pregnancy
  • a patient who is producing milk and breastfeeding
  • lung tissue problem

Dosage

Strengths: 100 mg

Non-Small Cell Lung Cancer

  • 400 mg orally once a day
  • Duration of therapy: Continue until disease progression or unacceptable toxicity
  • Select patients based on the presence of a RET (rearranged during transfection) gene fusion.
  • Information on FDA-approved tests for RET gene fusion is available at http://www.fda.gov/CompanionDiagnostics.

Thyroid Cancer

  • 400 mg orally once a day
  • Duration of therapy: Continue until disease progression or unacceptable toxicity
  • Select patients based on the presence of a RET (rearranged during transfection) gene fusion (thyroid cancer) or RET gene mutation (MTC).
  • However, FDA-approved gene fusion tests for RET gene fusion (thyroid cancer) and RET gene mutations are currently not available.
  • For the treatment of advanced or metastatic RET mutant medullary thyroid cancer (MTC) who require systemic therapy.
  • For the treatment of advanced or metastatic RET fusion-positive thyroid cancer who require systemic therapy and who are radioactive iodine-refractory (if radioactive iodine is appropriate).

Pediatric Dose for Thyroid Cancer

  • 12 years or older: 400 mg orally once a day
  • Duration of therapy: Continue until disease progression or unacceptable toxicity
  • Select patients based on the presence of a RET (rearranged during transfection) gene fusion (thyroid cancer) or RET gene mutation (MTC).
  • However, FDA-approved gene fusion tests for RET gene fusion (thyroid cancer) and RET gene mutations are currently not available.
  • For the treatment of advanced or metastatic RET mutant medullary thyroid cancer (MTC) who require systemic therapy.
  • For the treatment of advanced or metastatic RET fusion-positive thyroid cancer who require systemic therapy and who are radioactive iodine-refractory (if radioactive iodine is appropriate).

Renal Dose Adjustments

  • Mild to moderate renal impairment (CrCl 30 to less than 90 mL/min): No adjustment recommended.
  • Severe renal impairment (CrCl 15 to less than 30 mL/min): Data not available
  • ESRD: Data not available

Liver Dose Adjustments

  • Mild hepatic impairment (total bilirubin less than or equal to upper limit of normal [ULN] and AST greater than ULN; or total bilirubin greater than 1 to 1.5 x ULN and any AST): No adjustment recommended.
  • Moderate hepatic impairment (total bilirubin greater than 1.5 to 3 x ULN and any AST: Data not available
  • Severe hepatic impairment (total bilirubin greater than 3 x ULN and any AST): Data not available

Dose Adjustments

DOSE REDUCTIONS FOR ADVERSE REACTIONS:

  • First dose reduction: 300 mg orally once a day
  • Second dose reduction: 200 mg orally once a day
  • Third dose reduction: 100 mg orally once a day
  • Discontinue therapy in patients unable to tolerate 100 mg/day.

DOSE MODIFICATIONS FOR ADVERSE REACTIONS:
ILD/PNEUMONITIS:

  • Grade 1 or 2: Withhold therapy until resolution; resume at reduced dose
  • Grade 3 or 4 or recurrent: Permanently discontinue for confirmed ILD/pneumonitis

HYPERTENSION:

  • Grade 3: Withhold therapy for Grade 3 hypertension that persists despite optimal antihypertensives; resume at reduced dose when hypertension is controlled
  • Grade 4: Permanently discontinue therapy

HEPATOTOXICITY:

  • Grade 3 or 4: Withhold therapy, monitor transaminases weekly until recovery to Grade 1 or baseline; resume at reduced dose; if hepatotoxicity recurs at Grade 3 or higher, discontinue.

HEMORRHAGIC EVENTS:

  • Grade 3 or 4: Withhold therapy until recovery to baseline, Grade 0, or 1
  • Severe or life-threatening hemorrhagic events: Discontinue therapy

OTHER ADVERSE REACTIONS:

  • Grade 3 or 4: Withhold therapy until improvement to Grade 2 or less; resume at reduced dose
  • Recurrent Grade 4: Permanently discontinue

COADMINISTRATION WITH COMBINED P-GLYCOPROTEIN (P-gp) AND STRONG CYP450 3A INHIBITORS:

  • Avoid coadministration with combined P-gp and strong CYP450 3A inhibitors.
  • If coadministration cannot be avoided, reduce dose of pralsetinib (if current dose is 300 mg/day or 400 mg/day reduce dose to 200 mg/day; if current dose is 200 mg/day reduce dose to 100 mg/day).
  • After combined P-gp and strong CYP450 3A inhibitor has been discontinued for 3 to 5 elimination half-lives, resume pralsetinib at dose taken prior to initiating combined P-gp and strong CYP450 3A inhibitor

COADMINISTRATION WITH STRONG CYP450 3A INDUCERS:

  • Avoid coadministration with strong CYP450 3A inducers.
  • If coadministration with a strong CYP450 3A inducer cannot be avoided, increase the starting dose of pralsetinib to double the current dose starting on Day 7 of coadministration.
  • After CYP450 3A inducer has been discontinued for at least 14 days, resume pralsetinib at dose taken prior to initiating CYP450 3A inducer.

Administration advice:

  • Take orally on an empty stomach; no food should be consumed for at least 2 hours before and at least 1 hour after dosing

Side Effects

The Most Common

  • constipation
  • diarrhea
  • dry mouth
  • muscle or bone pain
  • swelling of hands, ankles, or feet
  • confusion, headache, shortness of breath, dizziness, or chest pain
  • fever, shortness of breath, or cough
  • pale skin, fatigue, or shortness of breath
  • yellowing of skin or eyes, dark-colored urine, bleeding or bruising more easily than normal, loss of appetite, decreased energy, or pain on the right side of the stomach area
  • black and tarry stools
  • red blood in stools
  • bloody vomit
  • vomiting material that looks like coffee grounds
  • coughing up blood
  • unusual bleeding or bruising
  • unusual vaginal bleeding
  • frequent nose bleeds
  • drowsiness, confusion, headache, or difficulty speaking
  • Bone pain
  • burning, numbness, tingling, or painful sensations
  • change in taste
  • constipation
  • decreased appetite

More common

  • Bleeding gums
  • blurred vision
  • chest pain
  • chills
  • cough
  • coughing up blood
  • dark urine
  • decrease or change in the amount of urine
  • difficulty in breathing or swallowing
  • dizziness
  • fainting
  • fast or slow heartbeat
  • fever
  • general feeling of discomfort or illness
  • headache
  • increased menstrual flow or vaginal bleeding
  • irregular pulse
  • joint pain, stiffness, or swelling
  • loss of appetite
  • lower back, side, or stomach pain
  • nausea
  • nervousness
  • nosebleeds
  • paralysis
  • pounding in the ears
  • prolonged bleeding from cuts
  • rapid weight gain
  • red or black, tarry stools
  • red or dark brown urine
  • slow or fast heartbeat
  • stomach pain, severe
  • swelling around the eye
  • swelling of the eyelids
  • swelling of the feet or lower legs
  • swelling or puffiness of the face
  • thickening of bronchial secretions
  • unusual tiredness or weakness
  • vomiting
  • yellow eyes or skin

Rare

  • Black, tarry stools
  • bladder pain
  • bloody or cloudy urine
  • chest pain or tightness
  • confusion
  • difficult, burning, or painful urination
  • frequent urge to urinate
  • lightheadedness
  • lower back or side pain
  • pale skin
  • sneezing
  • sore throat
  • sores, ulcers, or white spots on the lips or in the mouth
  • swollen glands
  • unusual bleeding or bruising
  • difficulty in moving
  • dry mouth
  • joint pain
  • lack or loss of strength
  • loss of taste
  • muscle aching or cramping
  • muscle pains or stiffness
  • neck pain
  • pain, swelling, or redness in the joints
  • swelling or inflammation of the mouth
  • tenderness
  • unsteadiness or awkwardness
  • watery or bloody diarrhea
  • weakness in the arms, hands, legs, or feet

Drug Interactions

Pregnancy and Lactation

US FDA pregnancy category: Not assigned.

Pregnancy

Based on findings from animal studies and its mechanism of action, this drug can cause fetal harm when administered to a pregnant woman. Pregnancy status should be verified prior to initiating therapy. If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential harm to the fetus. Females of reproductive potential should use effective nonhormonal contraception during therapy and for 2 weeks after; this drug may render hormonal contraceptives ineffective. Male patients with female partners of reproductive potential should use effective contraception during therapy and for 1 week after the final dose.

Lactation

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

How should this medicine be used?

Pralsetinib comes as a capsule to take by mouth. It is usually taken once daily on an empty stomach, at least 2 hours before and at least 1 hour after a meal. Take pralsetinib 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 pralsetinib exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

If you vomit after taking pralsetinib, do not take another dose. Continue your regular dosing schedule.

Your doctor may decrease your dose or temporarily or permanently stop your treatment if you experience certain side effects. Be sure to tell your doctor how you are feeling during your treatment with pralsetinib. Ask your pharmacist or doctor for a copy of the manufacturer’s information for the patient.

What special precautions should I follow?

Before taking pralsetinib,

  • tell your doctor and pharmacist if you are allergic to pralsetinib, any other medications, or any of the ingredients in pralsetinib capsules. Ask your pharmacist for a list of the ingredients.
  • tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention any of the following: antifungal medications including itraconazole (Onmel, Sporanox) and ketoconazole; clarithromycin (in Biaxin); certain HIV medications such as efavirenz (Sustiva, in Atripla, Symfi), indinavir (Crixivan), nelfinavir (Viracept), nevirapine (Viramune), ritonavir (Norvir, in Kaletra, Viekira Pak), and saquinavir (Invirase); oxcarbazepine (Oxtellar XR, Trileptal); phenobarbital; phenytoin (Dilantin, Phenytek); pioglitazone (Actos, in Oseni, Duetact); rifabutin (Mycobutin); and rifampin (Rifadin, Rimactane, in Rifater). Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
  • tell your doctor what herbal products you are taking, especially St. John’s wort.
  • tell your doctor if you have or have ever had lung or breathing problems other than lung cancer, bleeding problems, high blood pressure, or liver disease.
  • tell your doctor if you are pregnant, plan to become pregnant, or if you plan to father a child. Pralsetinib may interfere with the action of hormonal contraceptives (birth control pills, patches, rings, implants, or injections), so you should not use these as your only method of birth control during your treatment. You must use non-hormonal birth control such as a barrier method (a device that blocks sperm from entering the uterus such as a condom or a diaphragm). Ask your doctor to help you choose a method of birth control that will work for you. If you are female, you will need to have a pregnancy test before you start treatment, and you should use non-hormonal birth control to prevent pregnancy during your treatment and for 2 weeks after your final dose. If you are a male and your partner can become pregnant, you should use effective birth control to prevent pregnancy during your treatment and for 1 week after your final dose. You should know that this medication may decrease fertility in men and women; however, you should not assume that you cannot get pregnant or that you cannot get someone else pregnant. If you or your partner becomes pregnant while taking pralsetinib, call your doctor. Pralsetinib may harm the fetus.
  • tell your doctor if you are breastfeeding or plan to breastfeed. You should not breastfeed while taking trametinib and for 1 week after your final dose.
  • you should know that this medication may decrease fertility in men and women. Talk to your doctor about the risks of taking pralsetinib.
  • if you are having surgery, including dental surgery, tell the doctor or dentist that you are taking pralsetinib. Your doctor may tell you not to take pralsetinib 5 days before your surgery and will tell you when to start taking the medication again.
  • you should know that your blood pressure may increase during your treatment with pralsetinib. Your doctor will monitor your blood pressure carefully, and may prescribe medication to treat high blood pressure if it develops.
  • you should know that you may experience tumor lysis syndrome (TLS; a condition caused by the fast breakdown of cancer cells that can cause kidney failure and other complications) during your treatment with pralsetinib. To help reduce your risk of experiencing TLS, your doctor may ask you to drink water before and during your treatment, and each time your dose is increased. In addition, your doctor will give you a medication to take before starting and during your treatment to help prevent this side effect. If you experience any of the following symptoms of TLS, call your doctor immediately: fever, chills, nausea, vomiting, confusion, shortness of breath, seizures, irregular heartbeat, dark or cloudy urine, unusual tiredness, or muscle or joint pain.

References

  1. https://www.accessdata.fda.gov/drugsatfda_docs/label/2020/214701s000lbl.pdf
  2. https://www.fda.gov/drugs/resources-information-approved-drugs/fda-approves-pralsetinib-lung-cancer-ret-gene-fusions
  3. https://pubchem.ncbi.nlm.nih.gov/compound/Pralsetinib
  4. https://www.cancer.gov/about-cancer/treatment/drugs/pralsetinib
  5. https://medlineplus.gov/druginfo/meds/a620057.html
  6. https://go.drugbank.com/drugs/DB15822
  7. https://en.wikipedia.org/wiki/Pralsetinib
  8. https://www.drugs.com/pregnancy/pralsetinib.html
  9. https://www.webmd.com/drugs/2/drug-180055/pralsetinib-oral/details/list-contraindications
  10. https://www.mayoclinic.org/drugs-supplements/pralsetinib-oral-route/side-effects/drg-20502467?p=1
  11. Guide to Pharmacology Target Classification
  12. ChemIDplus Chemical Information Classification
  13. NCI Thesaurus Tree
  14. PubChem
  15. Anatomical Therapeutic Chemical (ATC) classification
    Target-based classification of drugs
  16. PATENT SCOPE