PARP inhibitor Pregnancy: Talzenna is not recommended during pregnancy or for women of childbearing potential not using contraception. There are no data from use in pregnant women; animal studies have shown embryo-foetal toxicity and it may cause foetal harm. A pregnancy test should be performed on all women of childbearing potential prior to treatment, and highly effective contraception used before starting, during treatment, and for 7 months after stopping (two non-hormonal and complementary methods in breast cancer, where hormonal contraception is not recommended). Male patients with female partners of reproductive potential or pregnant partners should use effective contraception (even after vasectomy) during treatment and for at least 4 months after the final dose. Breast-feeding is contraindicated during treatment and for at least 1 month after the final dose.

Talazoparib (Specialist drug)

Brand names: Talzenna

Talazoparib is an oral targeted anticancer agent (a PARP inhibitor) used in certain breast and prostate cancers, including BRCA-mutated disease.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 1 mg talazoparib once daily as monotherapy (breast cancer). In combination with enzalutamide for prostate cancer the recommended dose is 0.5 mg talazoparib once daily with 160 mg enzalutamide once daily.

Route: Oral — capsules swallowed whole, not opened or dissolved (to avoid contact with the capsule content); with or without food

Frequency: Once daily, until disease progression or unacceptable toxicity

Treatment should be initiated and supervised by a physician experienced in the use of anticancer medicinal products. Patient selection: for breast cancer, patients should be selected on the presence of deleterious or suspected deleterious germline BRCA mutations determined by an experienced laboratory using a validated test method; there is no requirement for tumour mutation testing to select patients with mCRPC. In the prostate cancer combination, medical castration with a luteinising hormone releasing hormone (LHRH) analogue should be continued during treatment in patients not surgically castrated — refer to the full enzalutamide product information for its posology. If the patient vomits or misses a dose, do not take an additional dose — take the next prescribed dose at the usual time. Dose reduction levels for monotherapy (breast cancer): starting 1 mg once daily; first reduction 0.75 mg once daily; second 0.5 mg once daily; third 0.25 mg once daily. Dose reduction levels in combination with enzalutamide (prostate cancer): starting 0.5 mg once daily; first reduction 0.35 mg once daily; second 0.25 mg once daily; third 0.1 mg once daily. The 0.1 mg capsule is intended to support dose modifications and is not interchangeable with other strengths. Dose adjustments for adverse reactions — withhold until haemoglobin recovers from < 8 g/dL to >= 9 g/dL, platelet count from < 50 000/microlitre to >= 75 000/microlitre, or neutrophil count from < 1 000/microlitre to >= 1 500/microlitre, then resume at the next lower dose; for Grade 3 or 4 non-haematologic reactions withhold until <= Grade 1, then consider resuming at the next lower dose or discontinue. Complete blood count should be obtained prior to starting therapy and monitored monthly and as clinically indicated. Hepatic impairment: no dose adjustment is required for mild, moderate or severe hepatic impairment; however the combination with enzalutamide is not recommended in severe hepatic impairment (Child-Pugh C) as pharmacokinetics and safety have not been established. Elderly: no dose adjustment necessary in patients >= 65 years. Paediatric: the safety and efficacy of Talzenna in children and adolescents < 18 years of age have not been established; no data are available. Note: eMC section 4.5 (interactions) was not present in the fetched bundle — the interaction entries below are drawn from §4.2 only; clinician to source the full §4.5 list.

Dose adjustments

Renal

Breast cancer (monotherapy): no dose adjustment for mild renal impairment (60 mL/min <= CrCL < 90 mL/min); for moderate renal impairment (30 mL/min <= CrCL < 60 mL/min) the recommended starting dose is 0.75 mg once daily; for severe renal impairment (15 mL/min <= CrCL < 30 mL/min) it is 0.5 mg once daily. Prostate cancer (with enzalutamide): no adjustment for mild renal impairment; for moderate renal impairment the recommended dose is 0.35 mg once daily and for severe renal impairment 0.25 mg once daily, each with enzalutamide once daily. Talzenna has not been studied in patients with CrCL < 15 mL/min or patients requiring haemodialysis.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to the active substance or to any of the excipients
Breast-feeding

Side effects

Anaemia (55.6%; Grade >= 3 in 39.2%)
Fatigue (52.5%)
Nausea (35.8%)
Neutropenia (30.3%; Grade >= 3 in 16.5%)
Thrombocytopenia (25.2%; Grade >= 3 in 11.1%)
Decreased appetite (21.1%); also very common: leukopenia, dizziness, headache. Uncommon but serious: myelodysplastic syndrome/acute myeloid leukaemia. A higher incidence of venous thromboembolic events was seen with the enzalutamide combination in mCRPC

Interactions

Strong P-glycoprotein (P-gp) inhibitors — may increase talazoparib exposure; concomitant use during talazoparib treatment should be avoided. If co-administration with a strong P-gp inhibitor is unavoidable during monotherapy for breast cancer, reduce the Talzenna dose to the next lower dose, and increase it back (after 3-5 half-lives of the inhibitor) once the inhibitor is discontinued (from eMC §4.2)
P-gp inhibitors with the enzalutamide combination (prostate cancer) — the effect on talazoparib exposure has not been studied, therefore concomitant use of P-gp inhibitors should be avoided (from eMC §4.2)
Enzalutamide — given deliberately in combination for prostate cancer at 160 mg once daily; refer to the full enzalutamide product information for its own dose adjustments (from eMC §4.2)
Note: eMC section 4.5 was not present in the fetched bundle; the above are drawn from the posology section only

Clinical monograph

How it works

It inhibits poly(ADP-ribose) polymerase (PARP) enzymes and traps PARP on DNA, so cancer cells with defective homologous-recombination repair (such as BRCA-mutated cells) cannot repair DNA damage and undergo cell death.

Prescribing in practice

Myelosuppression, particularly anaemia, is common and can be severe, so blood counts must be checked before and regularly during treatment with dose adjustment or interruption as needed.
Rare but serious myelodysplastic syndrome and acute myeloid leukaemia have been reported with PARP inhibitors.
It is a P-glycoprotein and BCRP substrate, so interacting medicines should be reviewed against the SPC.

Monitoring

Monitor the full blood count before starting and regularly throughout treatment, watching for persistent or unexplained cytopenias.

Counselling the patient

Report unusual tiredness, bruising, bleeding, or signs of infection.
Use effective contraception during and after treatment as advised, as this drug can harm a developing baby.
Take the capsules as directed and attend all blood-test appointments.

Evidence & guidelines

Efficacy in BRCA-mutated advanced breast cancer was shown in a randomised phase 3 trial, with use reflected in NICE guidance.

Reference: NICE TA760; SmPC; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

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