Talzenna: Uses, Dosage & Side Effects

What Is Talzenna and What Is It Used For?

Talzenna contains the active substance talazoparib, which belongs to a class of anticancer drugs called PARP inhibitors (poly adenosine diphosphate-ribose polymerase inhibitors). PARP enzymes play a critical role in the cell’s ability to repair single-strand breaks in DNA. When functioning normally, these enzymes detect DNA damage, bind to the site of damage, and facilitate repair. Talazoparib exploits this mechanism in a twofold manner: it catalytically inhibits PARP enzymatic activity, and — crucially — it traps the PARP protein on the damaged DNA strand, creating a physical barrier to DNA replication and transcription that is highly toxic to the cell.

The concept underpinning Talzenna’s effectiveness is known as synthetic lethality. In healthy cells, multiple DNA repair pathways exist to maintain genomic integrity, including both the base excision repair pathway (which relies on PARP) and the homologous recombination repair pathway (which relies on BRCA1 and BRCA2 proteins, among others). When a cancer cell carries a mutation in the BRCA1 or BRCA2 gene, its homologous recombination repair pathway is already compromised. By additionally blocking the PARP-dependent repair pathway with talazoparib, the cancer cell accumulates so much unrepaired DNA damage that it cannot survive and undergoes cell death (apoptosis). Normal cells, which typically retain at least one functional copy of the BRCA genes, can still repair DNA through homologous recombination and are therefore less affected by PARP inhibition.

Talazoparib is considered one of the most potent PARP inhibitors in clinical use, largely because of its superior PARP-trapping ability compared to other agents in this class such as olaparib, rucaparib, and niraparib. In preclinical studies, talazoparib demonstrated approximately 100-fold greater PARP-trapping potency than some competitors, which contributes to its efficacy at relatively low doses (1 mg daily for breast cancer) and its distinctive side-effect profile, particularly with regard to myelosuppression.

Talzenna is approved by the European Medicines Agency (EMA), the U.S. Food and Drug Administration (FDA), and regulatory bodies worldwide for the following indications:

• HER2-negative metastatic breast cancer with germline BRCA mutation: Talzenna is used as monotherapy for the treatment of adult patients with HER2-negative locally advanced or metastatic breast cancer who carry an inherited (germline) harmful BRCA1 or BRCA2 mutation. Patients must have received prior chemotherapy in the neoadjuvant, adjuvant, or metastatic setting (unless unsuitable for such therapy). The landmark EMBRACA trial demonstrated that talazoparib significantly improved progression-free survival (8.6 months vs. 5.6 months) and objective response rate (62.6% vs. 27.2%) compared with physician’s choice of single-agent chemotherapy.
• Metastatic castration-resistant prostate cancer (mCRPC): Talzenna is used in combination with the androgen receptor inhibitor enzalutamide for the treatment of adult patients with mCRPC in whom chemotherapy is not clinically indicated. This indication does not require a specific BRCA mutation, although the greatest benefit has been observed in patients with homologous recombination repair (HRR) gene alterations. The TALAPRO-2 trial showed that the combination of talazoparib plus enzalutamide significantly extended radiographic progression-free survival compared with enzalutamide alone.

In both indications, Talzenna is used when the cancer has spread beyond the original tumor (metastatic disease). For breast cancer, a confirmed germline BRCA mutation is required and must be identified through an approved genetic test before starting treatment. For prostate cancer, the treatment is used in the castration-resistant setting, meaning the cancer has progressed despite hormone therapy or surgical intervention to reduce testosterone levels.

What Should You Know Before Taking Talzenna?

Before starting treatment with Talzenna, your healthcare provider will conduct a thorough evaluation that includes genetic testing (for breast cancer indication), a complete blood count, assessment of liver and kidney function, and a pregnancy test for women of childbearing potential. Understanding the contraindications, warnings, and precautions associated with this medication is essential for safe and effective treatment.

Contraindications

Talzenna must not be taken in the following circumstances:

• Allergy to talazoparib or excipients: If you are allergic to talazoparib or any of the other ingredients in the capsules (including silicified microcrystalline cellulose, hypromellos, titanium dioxide, or iron oxides), do not take this medicine. Signs of an allergic reaction may include skin rash, itching, swelling of the face or throat, difficulty breathing, or dizziness.
• Breastfeeding: You must not breastfeed while taking Talzenna and for at least 1 month after the last dose. It is not known whether talazoparib passes into breast milk, but given the mechanism of action and potential for serious adverse effects in the nursing infant, breastfeeding is contraindicated during treatment.

Warnings and Precautions

Several important warnings apply to the use of Talzenna. Discuss all of the following with your healthcare provider before and during treatment:

In rare cases, persistently low blood cell counts may indicate a more serious bone marrow condition such as myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML). These are serious blood disorders that have been reported in patients treated with PARP inhibitors, including talazoparib. Your doctor may perform bone marrow biopsies if there is clinical concern. Patients who have received prior chemotherapy (particularly platinum-based agents or alkylating agents) may be at higher risk for these complications.

Pregnancy and Breastfeeding

Talzenna can cause serious harm to a developing baby. Based on its mechanism of action and findings from animal studies, talazoparib is expected to be teratogenic (capable of causing birth defects) and embryotoxic. The following precautions are essential:

• Pregnancy: Do not use Talzenna if you are pregnant unless your doctor determines that the benefit clearly outweighs the risk. A pregnancy test must be performed before starting treatment. If you become pregnant during treatment, inform your healthcare provider immediately.
• Contraception for women: Women of childbearing potential must use effective non-hormonal contraception during treatment and for at least 7 months after the last dose. Because hormonal contraceptives are not recommended for patients with breast cancer, two non-hormonal methods should be used. Discuss suitable options with your doctor or midwife.
• Contraception for men: Male patients with female partners who are pregnant or could become pregnant must use effective contraception (including after vasectomy) during treatment and for at least 4 months after the last dose of Talzenna.
• Breastfeeding: Do not breastfeed during treatment and for at least 1 month after the last dose.
• Fertility: Talazoparib may impair male fertility. Men should consider sperm preservation before starting treatment.

Children and Adolescents

Talzenna is not approved for use in children or adolescents under 18 years of age. The safety and efficacy of talazoparib have not been established in this population.

Driving and Operating Machinery

Talzenna may have a minor effect on the ability to drive and use machines. Dizziness, weakness, and fatigue are very common side effects. If you experience any of these symptoms, avoid driving vehicles or operating machinery until the effects subside.

How Does Talzenna Interact with Other Drugs?

Drug interactions are an important consideration when taking Talzenna. Talazoparib is a substrate of P-glycoprotein (P-gp), a transport protein that affects how the drug is absorbed, distributed, and eliminated from the body. Medications that inhibit or induce P-gp can therefore significantly alter talazoparib blood levels, increasing the risk of side effects or reducing therapeutic efficacy. Additionally, certain strong CYP3A enzyme inducers can reduce talazoparib levels. Always inform your healthcare provider about all prescription medications, over-the-counter drugs, herbal remedies, and dietary supplements you are currently using or plan to use.

Major Interactions — Drugs That May Increase Talzenna Side Effects

The following medications are P-gp inhibitors that can increase talazoparib blood concentrations and thereby increase the risk and severity of adverse effects. If co-administration cannot be avoided, your doctor may need to reduce the Talzenna dose:

Additional antiretroviral agents that may interact with Talzenna include cobicistat, darunavir, indinavir, lopinavir, saquinavir, telaprevir, and tipranavir. If you are receiving treatment for HIV/AIDS, it is especially important that your oncologist and infectious disease specialist communicate to manage these interactions.

Drugs That May Decrease Talzenna’s Effectiveness

The following substances can reduce talazoparib blood levels, potentially making the treatment less effective:

• Carbamazepine and phenytoin: Antiepileptic medications used to control seizures. These are potent enzyme inducers that can accelerate the metabolism and excretion of talazoparib.
• St. John’s Wort (Hypericum perforatum): An herbal supplement commonly used for mild depression and anxiety. It is a potent inducer of drug-metabolizing enzymes and transporters, and its use with Talzenna should be avoided entirely.

Food and Supplement Interactions

Do not use dietary supplements containing curcumin while taking Talzenna, as curcumin can increase talazoparib blood levels and the risk of side effects. Curcumin is found in turmeric, and while using small amounts of turmeric as a cooking spice is unlikely to cause problems, concentrated curcumin supplements or high-dose turmeric products should be avoided throughout your treatment.

What Is the Correct Dosage of Talzenna?

Always take Talzenna exactly as prescribed by your doctor or pharmacist. The dose may be adjusted based on your individual tolerance, side effects, and kidney function. Multiple capsule strengths are available to allow precise dose adjustments without changing the number of capsules taken per day.

Adults — Standard Dosing

Dose Reductions

If you experience certain side effects (particularly low blood cell counts), your doctor may reduce your dose or temporarily pause treatment. Available dose reduction levels include:

Various capsule strengths (0.1 mg, 0.25 mg, 0.35 mg, 0.5 mg, and 1 mg) are available to facilitate dose adjustments. Your doctor will prescribe the appropriate combination of capsule strengths. Treatment should be permanently discontinued if a dose below the lowest recommended reduction level is required.

How to Take Talzenna

• Take Talzenna once daily, at approximately the same time each day.
• Swallow the capsule whole with a glass of water.
• Do not chew, crush, or open the capsules. Avoid contact with the capsule contents.
• Talzenna can be taken with food or between meals.

Children

Talzenna is not approved for use in children or adolescents under 18 years. No dosage recommendations are available for this age group.

Elderly

No specific dose adjustment is required for elderly patients based on age alone. However, elderly patients may be more susceptible to side effects, particularly myelosuppression, and should be monitored closely. Dose adjustments are made based on tolerability and side effects, not age.

Missed Dose

If you miss a dose or vomit after taking a dose, do not take an extra dose. Simply take your next scheduled dose at the regular time. Never take a double dose to make up for a missed or vomited dose.

Overdose

If you take more Talzenna than prescribed, contact your doctor or go to the nearest hospital emergency department immediately. Bring the medication package and this information with you so the healthcare team knows what you have taken. There is no specific antidote for talazoparib overdose; treatment is supportive and based on symptoms.

What Are the Side Effects of Talzenna?

Like all medicines, Talzenna can cause side effects, although not everybody experiences them. The side effects of talazoparib are largely related to its mechanism of action: because PARP enzymes are involved in DNA repair in all rapidly dividing cells (not just cancer cells), the bone marrow — which produces blood cells at a very high rate — is particularly affected. This accounts for the high frequency of hematological (blood-related) side effects.

Contact your doctor immediately if you develop any of the following symptoms, which may indicate a serious blood disorder:

The severity and frequency of side effects may differ depending on whether Talzenna is used alone (for breast cancer) or in combination with enzalutamide (for prostate cancer). When used in combination, additional side effects related to enzalutamide may occur, and your doctor will monitor for these as well.

Most hematological side effects are manageable through dose reductions, treatment interruptions, and supportive care such as blood transfusions or growth factor support. Your doctor will perform regular blood tests — typically weekly during the first month, then monthly thereafter — to monitor your blood counts and adjust treatment as needed.

How Should You Store Talzenna?

Proper storage of Talzenna is important to maintain the quality, safety, and effectiveness of the medication. Follow these storage guidelines carefully:

• Keep out of reach of children: Store Talzenna where children cannot see or reach it. Talazoparib is a cytotoxic medication, and accidental ingestion by a child could be extremely dangerous.
• Expiration date: Do not use Talzenna after the expiration date (EXP) stated on the carton and bottle or blister pack. The expiration date refers to the last day of that month.
• Storage conditions: No special storage conditions are required for Talzenna. Store at room temperature away from excessive heat and moisture.
• Packaging integrity: Do not use this medicine if the packaging appears damaged or shows signs of tampering.
• Disposal: Do not dispose of Talzenna via wastewater or household waste. Return unused or expired medication to your pharmacist for safe disposal. This protects the environment and prevents accidental exposure.

Talzenna is available in both plastic bottles (containing 30 hard capsules) and perforated unit-dose blister packs (containing 30, 60, or 90 hard capsules, depending on the strength). Both packaging types provide adequate protection for the capsules under normal storage conditions.

What Does Talzenna Contain?

Understanding the full composition of your medication is important, particularly if you have any known allergies to specific pharmaceutical ingredients. Each Talzenna hard capsule contains the active substance as talazoparib tosylate (a salt form that improves absorption).

Active Ingredient

Inactive Ingredients (Excipients)

• Capsule contents: Silicified microcrystalline cellulose (microcrystalline cellulose and silicon dioxide)
• Capsule shell: Hypromellose, titanium dioxide (E171), and iron oxides (E172) — specific iron oxide colors vary by capsule strength (yellow iron oxide for 0.25 mg, 0.35 mg, and 1 mg; red iron oxide for 0.5 mg and 1 mg)
• Printing ink: Shellac (E904), propylene glycol (E1520), ammonium hydroxide (E527), black iron oxide (E172), and potassium hydroxide (E525)

All capsules are opaque and approximately 14 mm × 5 mm in size. Not all pack sizes may be marketed in every country. The marketing authorization holder is Pfizer Europe MA EEIG, Brussels, Belgium, and the manufacturer is Excella GmbH & Co. KG, Feucht, Germany.