Prostate cancer pill pair approved earlier for DNA repair genes

Men whose prostate cancer has spread but still responds to hormone therapy can now be offered a PARP inhibitor from the start in the US, provided their tumour carries a mutation in a DNA repair gene. On 26 October 2026 the US Food and Drug Administration (FDA) approved talazoparib (Talzenna) taken with enzalutamide (Xtandi) for this group.

The decision rests on one trial, TALAPRO-3. In it, adding talazoparib cut the risk of the cancer growing on scans, or of death, by 52% compared with enzalutamide plus a dummy pill.

Until now the pairing was only approved later in the disease. This moves it up the queue.

Who the approval covers

The FDA label uses a mouthful of a name: metastatic androgen pathway modulation-naive or -sensitive prostate cancer. Most doctors and patients know it as metastatic hormone-sensitive prostate cancer, or mHSPC. It means the cancer has spread beyond the prostate, but it still shrinks or stalls when testosterone is switched off.

The approval only applies to men whose cancer has a change in one of 12 homologous recombination repair (HRR) genes. The FDA lists them as ATM, ATR, BRCA1, BRCA2, CDK12, CHEK2, FANCA, MLH1, MRE11A, NBN, PALB2 and RAD51C. The mutation has to be found with an FDA-authorised test.

Pfizer, which makes talazoparib and co-markets enzalutamide with Astellas in the US, cites research suggesting about 25% of men with mHSPC have an HRR mutation. That figure comes from a 2022 study in Clinical Genitourinary Cancer referenced in Pfizer's announcement, so treat it as an estimate.

All men on the combination also need ongoing hormone therapy, either a GnRH analogue injection or previous surgical removal of the testicles.

How the two drugs work together

Enzalutamide is an androgen receptor pathway inhibitor. It blocks the receptor that testosterone uses to drive prostate cancer growth. It has been a standard treatment for years and is already approved for hormone-sensitive disease on its own.

Talazoparib is a PARP inhibitor. PARP is an enzyme cells use to patch up breaks in their DNA. Cancer cells that already have a faulty HRR gene lean heavily on PARP to survive, so blocking it can push them past the point of repair. Pfizer says lab work shows talazoparib also traps PARP on damaged DNA, which adds to the harm done to the cancer cell.

The idea behind TALAPRO-3 was simple. Hit the hormone signal and the DNA repair weakness at the same time, early, before the cancer learns to resist hormone therapy.

What TALAPRO-3 found

TALAPRO-3 (NCT04821622) was a double-blind, placebo-controlled phase 3 trial. Neither the patients nor their doctors knew who was getting talazoparib. It enrolled 599 men with HRR-mutated mHSPC at sites across the US, Canada, Europe, South America and the Asia-Pacific region. Men could have had up to three months of hormone therapy before joining.

They were split evenly between two groups:

• talazoparib 0.5 mg a day plus enzalutamide 160 mg a day
• a placebo plus enzalutamide 160 mg a day

The main measure was radiographic progression-free survival. That is the time until scans show the cancer growing, or until death.

A hazard ratio of 0.48 means that at any point during the trial, men on the combination were about half as likely to have their cancer progress or to die. According to Fierce Pharma, Pfizer had set itself a target of a 37% reduction when designing the study, and the result went well past it.

Pfizer reports the benefit was consistent in men with BRCA mutations and in men with other HRR mutations. That second group matters for the size of the label, because BRCA changes are only part of the HRR picture.

The results were presented at the 2026 American Society of Clinical Oncology meeting and published at the same time in the New England Journal of Medicine.

What we still don't know about survival

Overall survival is the number most men want to hear about, and it isn't available yet. The FDA notes that at the time of the progression analysis, overall survival data were immature. In plain terms, too few men had died in either group to say whether talazoparib helps people live longer.

Pfizer's own forward-looking statement lists "whether the TALAPRO-3 trial will meet the key secondary endpoint for overall survival" as an open risk. So the approval is based on delaying progression, which is a real benefit for many men, but the survival answer is still to come. For more on how to weigh a result like this, see our guide on reading clinical trial results without being misled by risk.

The side effects that come with it

Anaemia is the big one. In TALAPRO-3, severe (grade 3 or higher) anaemia hit 51% of men on the combination against 3% on enzalutamide alone. Five percent stopped talazoparib because of it.

The prescribing information gives a fuller picture from the wider prostate cancer data. Across men taking talazoparib with enzalutamide in the earlier trial programme:

• severe anaemia affected 49%, severe neutropenia (low white cells) 19% and severe thrombocytopenia (low platelets) 9%
• 41% needed a red blood cell transfusion, and 25% needed more than one
• other common problems were fatigue, back pain, loss of appetite and nausea

There is also a rare but serious risk of the blood cancers myelodysplastic syndrome and acute myeloid leukaemia. Pfizer's label puts the cumulative rate at about 1% across 1,096 patients given talazoparib alone or with enzalutamide, with 0.6% fatal. The rate in the comparison groups was 0.2%. Blood counts are checked monthly on treatment.

Enzalutamide brings its own known risks, which the label lists. They include falls and fractures, raised blood pressure and a small risk of seizures. In pooled placebo-controlled trials, falls occurred in 12% of men on enzalutamide against 6% on placebo.

Men with moderate or severe kidney problems need a lower talazoparib dose.

A worked example of what the numbers could mean

Here is a rough way to picture the three-year figure. Take 100 men with HRR-mutated mHSPC who start talazoparib plus enzalutamide. Based on Pfizer's estimate, about 77 would be expected to have no scan progression three years later.

The release doesn't give the matching three-year figure for the enzalutamide-only group, so the honest comparison is the hazard ratio and the medians. Half of the control group had progressed by 45.8 months. In the talazoparib group, fewer than half had progressed by the time of analysis, which is why the median isn't reached.

Now set that against the side effects. Of the same 100 men, roughly 51 would have severe anaemia at some point, and dozens would need at least one transfusion. That's the trade being offered. Many men will find it worthwhile. Some, especially those with other health problems or who already struggle with fatigue, may not.

Why testing at diagnosis is now more important

Before this approval, many men with spread prostate cancer weren't tested for HRR mutations until their cancer had become resistant to hormone therapy. That made sense when PARP inhibitors were only approved at that later stage.

Neeraj Agarwal of Dana-Farber Cancer Institute, the global lead investigator for TALAPRO-3, said in Pfizer's release that the result reinforces "the importance of biomarker testing at the time of diagnosis."

The FDA names two companion tests: FoundationOne CDx, which uses tumour tissue, and FoundationOne Liquid CDx, which uses a blood sample. Blood tests pick up DNA shed by the tumour, and a negative blood result doesn't always rule out a mutation in the tumour itself. So if the blood test finds nothing, it is reasonable to ask whether tissue can be tested as well.

If you've been diagnosed with spread prostate cancer and haven't been asked about genetic testing of your tumour, it's a fair question to raise.

Where this leaves patients in the UK and Europe

This is a US decision. Pfizer says an application for the same use is under review at the European Medicines Agency, with other filings planned or underway. The FDA reviewed it under Project Orbis, a scheme that lets several regulators look at a cancer drug at the same time, but Pfizer's release doesn't name which other countries took part.

In the EU, talazoparib with enzalutamide has been approved since January 2024 for castration-resistant disease when chemotherapy isn't suitable. The hormone-sensitive use is not yet approved there. In the UK, it would need a decision from the Medicines and Healthcare products Regulatory Agency and then a NICE appraisal before routine NHS use. Our explainer on how new medicines get approved by the FDA, MHRA and NICE walks through those steps.

For a recent example of another cancer drug taking the FDA route ahead of Europe, see our report on the Jemperli approval for rectal cancer.

Questions worth asking your specialist

If you or someone close to you has newly diagnosed spread prostate cancer, these are practical things to bring to the next appointment:

1. Has my tumour been tested for HRR gene mutations, and with which test?
2. If the blood test was negative, can the tissue be tested too?
3. How often will my blood counts be checked, and what happens if I need a transfusion?
4. Is the combination available where I'm being treated, or only through a trial?

The next thing to watch is the overall survival readout from TALAPRO-3, which will show whether delaying progression early also means longer lives.

This article explains published trial results and regulatory decisions. It is not medical advice. Talk to your own doctor about any treatment decision.