On May 30, 2026 Pfizer Inc. (NYSE: PFE) reported detailed results from the pivotal Phase 3 TALAPRO-3 study of TALZENNA (talazoparib), an oral poly ADP-ribose polymerase (PARP) inhibitor, in combination with XTANDI (enzalutamide), an androgen receptor pathway inhibitor (ARPI), in men with homologous recombination repair (HRR) gene-mutated metastatic castration-sensitive prostate cancer (mCSPC), also known as metastatic hormone-sensitive prostate cancer (mHSPC). These results will be presented today in a late-breaking oral presentation (Abstract LBA5007) at the 2026 American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Annual Meeting and simultaneously published in The New England Journal of Medicine.
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TALZENNA plus XTANDI demonstrated a 52% reduction in the risk of radiographic progression or death compared to placebo plus XTANDI (Hazard Ratio [HR] of 0.48; 95% Confidence Interval [CI], 0.36–0.65; p ˂ 0.0001). At three years, radiographic progression-free survival (rPFS) rates were estimated at 77% in patients treated with TALZENNA plus XTANDI versus 56% in patients treated with placebo plus XTANDI. With a median follow-up of over 37 months, median rPFS was not reached in the TALZENNA plus XTANDI arm and was 46 months with placebo and XTANDI.
The rPFS benefit observed with TALZENNA plus XTANDI was consistent across pre-specified groups with various patient and disease characteristics, including age, Gleason score, geographic region, prostate-specific antigen (PSA) level, and BRCA vs. non-BRCA HRR gene alteration status. At three years, rPFS rates were estimated at 77% vs. 49% in patients with cancer harboring BRCA alterations (HR, 0.37; 95% CI, 0.22–0.61) and 76% vs. 60% in patients with cancer with non-BRCA alterations (HR, 0.57; 95% CI, 0.39–0.82), compared with placebo plus XTANDI.
"Delaying progression to castration‑resistant disease, the most symptomatic and lethal phase of prostate cancer, remains a significant challenge to patients with mCSPC – especially to those with HRR gene alterations, who often experience poorer outcomes," said Neeraj Agarwal, M.D., FASCO, Presidential Chair of Cancer Research at Huntsman Cancer Institute at the University of Utah and global lead investigator for TALAPRO-3. "With more than three years of follow‑up and median radiographic progression‑free survival not reached, TALZENNA plus XTANDI demonstrated durable disease control across a broad HRR‑altered population, including patients with BRCA and non‑BRCA alterations. These findings underscore the importance of genetic testing as part of routine care and highlight the potential for TALZENNA plus XTANDI to meaningfully improve the outcomes of patients with HRRm mCSPC."
Interim overall survival (OS) results showed a strong trend toward improved OS, a key secondary endpoint, with median OS not reached in either treatment arm (HR, 0.77; 95% CI, 0.56–1.04; p = 0.09). TALZENNA plus XTANDI also improved time to PSA progression (HR, 0.51; 95% CI, 0.37–0.71; p < 0.0001) and time to subsequent anti-cancer therapy (HR, 0.51; 95% CI, 0.38–0.70; p < 0.0001) vs. placebo plus XTANDI. The trial remains ongoing, and OS will be formally assessed at the final analysis.
In TALAPRO-3, the safety profile of TALZENNA plus XTANDI was consistent with the known profiles of each agent, and no new safety signals were identified. The most common treatment-emergent adverse events (TEAEs) in the TALZENNA plus XTANDI group were anemia, fatigue, decreased neutrophil count, and asthenia. The most common grade 3 or higher TEAE was anemia, reported by 51% in the TALZENNA plus XTANDI group and 3% in the control group. Five percent of patients discontinued TALZENNA due to anemia. TEAEs were generally manageable with dose modifications and supportive care as needed.
"Men with HRR gene-mutated metastatic prostate cancer face significant challenges, with faster disease progression and limited treatment options, making it critical to intervene as early in the course of disease as possible," said Jeff Legos, Chief Oncology Officer, Pfizer. "The benefit seen with TALZENNA plus XTANDI across a full spectrum of HRR gene alterations reinforces its potential to fundamentally change clinical practice, giving patients significantly more time before disease progression as compared to the current standard of care."
Prostate cancer is the second most common cancer in men worldwide, with an estimated 1.5 million new cases diagnosed globally1 and 330,000 new cases anticipated in the United States in 2026.2 mCSPC is a form of advanced prostate cancer that has spread beyond the prostate but is still sensitive to androgen deprivation therapy.3 Approximately 5–10% of newly diagnosed cases are mCSPC,4,5 and up to 30% of these patients harbor HRR gene alterations.6
TALZENNA plus XTANDI in HRR gene-mutated mCSPC is an investigational treatment regimen. The results from TALAPRO-3 are being discussed with global health authorities to potentially expand the combination regimen’s existing indication. TALZENNA plus XTANDI is currently approved in more than 60 countries, including in the U.S. for adults with HRR gene-mutated mCRPC and in the European Union for adults with mCRPC in whom chemotherapy is not clinically indicated.
Pfizer is continuing its commitment to help non-scientists understand the latest findings with the development of abstract plain language summaries (APLS) for company-sponsored research being presented at ASCO (Free ASCO Whitepaper), which are written in non-technical language. Those interested in learning more can visit www.Pfizer.com/apls to access the summaries.
About TALAPRO-3
The Phase 3 TALAPRO-3 trial is a multicenter, randomized, double-blind, placebo-controlled study that enrolled 599 patients with mCSPC (with ≤3 months of ADT [chemical or surgical] with or without an approved ARPI in the mCSPC setting) at sites in the U.S., Canada, Europe, South America, and the Asia-Pacific region. Patients with histologically/cytologically confirmed adenocarcinoma of the prostate without neuroendocrine differentiation, small cell, or signet cell features and with alterations in one or more HRR genes (as per HRR12 gene panel) in the trial were randomized to receive TALZENNA 0.5 mg/day plus XTANDI 160mg/day, or placebo plus XTANDI 160mg/day.
The primary endpoint of the trial is investigator-assessed rPFS, defined as the time from the date of randomization to radiographic progression in soft tissue per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1), or in bone per Prostate Cancer Working Group 3 (PCWG3) criteria by investigator assessment, or death, whichever occurs first. Secondary endpoints include OS, objective response rate, duration of response, and patient-reported outcomes.
For more information on the TALAPRO-3 trial (NCT04821622), go to www.clinicaltrials.gov.
About TALZENNA (talazoparib)
TALZENNA is an oral inhibitor of poly ADP-ribose polymerase (PARP), which plays a role in DNA damage repair. Preclinical studies have demonstrated that TALZENNA blocks PARP enzyme activity and traps PARP at the site of DNA damage, leading to decreased cancer cell growth and cancer cell death.
TALZENNA was initially approved in the U.S., EU, and multiple other regions as a single agent for the treatment of adult patients with deleterious or suspected deleterious gBRCAm HER2-negative locally advanced or metastatic breast cancer.
TALZENNA in combination with XTANDI was approved by the U.S. Food and Drug Administration (FDA) for the treatment of adult patients with HRR gene-mutated mCRPC in June 2023. The combination was also approved by the European Commission in January 2024 for the treatment of adult patients with mCRPC in whom chemotherapy is not clinically indicated. TALZENNA in combination with XTANDI is approved in more than 60 countries, indications vary by country.
TALZENNA (talazoparib) Indication in the U.S.
TALZENNA is a poly (ADP-ribose) polymerase (PARP) inhibitor indicated for:
HRR gene-mutated mCRPC:
In combination with enzalutamide for the treatment of adult patients with homologous recombination repair (HRR) gene-mutated metastatic castration-resistant prostate cancer (mCRPC).
Breast Cancer:
As a single agent, for the treatment of adult patients with deleterious or suspected deleterious germline BRCA-mutated (gBRCAm) HER2-negative locally advanced or metastatic breast cancer. Select patients for therapy based on an FDA-approved companion diagnostic for TALZENNA.
TALZENNA (talazoparib) Important Safety Information
WARNINGS and PRECAUTIONS
Myelodysplastic Syndrome/Acute Myeloid Leukemia (MDS/AML), including cases with a fatal outcome, has been reported in patients who received TALZENNA. Overall, MDS/AML has been reported in 0.4% (3 out of 788) of solid tumor patients treated with TALZENNA as a single agent in clinical studies. In TALAPRO-2, MDS/AML occurred in 2 out of 511 (0.4%) patients treated with TALZENNA and enzalutamide and in 0 out of 517 (0%) patients treated with placebo and enzalutamide. The durations of TALZENNA treatment in these 5 patients prior to developing MDS/AML were 0.3, 1, 2, 3, and 5 years. Most of these patients had received previous chemotherapy with platinum agents and/or other DNA damaging agents including radiotherapy.
Do not start TALZENNA until patients have adequately recovered from hematological toxicity caused by previous chemotherapy. Monitor blood counts monthly during treatment with TALZENNA. For prolonged hematological toxicities, interrupt TALZENNA and monitor blood counts weekly until recovery. If counts do not recover within 4 weeks, refer the patient to a hematologist for further investigations including bone marrow analysis and blood sample for cytogenetics. If MDS/AML is confirmed, discontinue TALZENNA.
Myelosuppression consisting of anemia, neutropenia, and/or thrombocytopenia, have been reported in patients treated with TALZENNA. In TALAPRO-2, Grade ≥3 anemia, neutropenia, and thrombocytopenia were reported, respectively, in 48%, 19%, and 9% of patients receiving TALZENNA and enzalutamide. Forty-two percent of patients (216/511) required a red blood cell transfusion, including 25% (127/511) who required more than one transfusion. Discontinuation due to anemia, neutropenia, and thrombocytopenia occurred, respectively, in 8%, 3%, and 0.4% of patients.
Withhold TALZENNA until patients have adequately recovered from hematological toxicity caused by previous therapy. Monitor blood counts monthly during treatment with TALZENNA. If hematological toxicities do not resolve within 28 days, discontinue TALZENNA and refer the patient to a hematologist for further investigations including bone marrow analysis and blood sample for cytogenetics.
Embryo-Fetal Toxicity TALZENNA can cause fetal harm when administered to pregnant women. Advise male patients with female partners of reproductive potential or who are pregnant to use effective contraception during treatment and for 4 months following the last dose of TALZENNA.
ADVERSE REACTIONS
Serious adverse reactions reported in >2% of patients included anemia (9%) and fracture (3%). Fatal adverse reactions occurred in 1.5% of patients, including pneumonia, COVID infection, and sepsis (1 patient each).
The most common adverse reactions (≥ 10%, all Grades), including laboratory abnormalities, for patients in the TALAPRO-2 study who received TALZENNA with enzalutamide vs patients receiving placebo with enzalutamide were hemoglobin decreased (79% vs 34%), neutrophils decreased (60% vs 18%), lymphocytes decreased (58% vs 36%), fatigue (49% vs 40%), platelets decreased (45% vs 8%), calcium decreased (25% vs 11%), nausea (21% vs 17%), decreased appetite (20% vs 14%), sodium decreased (22% vs 20%), phosphate decreased (17% vs 13%), fractures (14% vs 10%), magnesium decreased (14% vs 12%), dizziness (13% vs 9%), bilirubin increased (11% vs 7%), potassium decreased (11% vs 7%), and dysgeusia (10% vs 4.5%).
Clinically relevant adverse reactions in <10% of patients who received TALZENNA with enzalutamide included abdominal pain (9%), vomiting (9%), alopecia (7%), dyspepsia (4%), venous thromboembolism (3%) and stomatitis (2%).
DRUG INTERACTIONS
Coadministration with P-gp inhibitors The effect of coadministration of P-gp inhibitors on talazoparib exposure when TALZENNA is taken with enzalutamide has not been studied. Monitor patients for increased adverse reactions and modify the dosage as recommended for adverse reactions when TALZENNA is coadministered with a P-gp inhibitor.
Coadministration with BCRP inhibitors Monitor patients for increased adverse reactions and modify the dosage as recommended for adverse reactions when TALZENNA is coadministered with a BCRP inhibitor. Coadministration of TALZENNA with BCRP inhibitors may increase talazoparib exposure, which may increase the risk of adverse reactions.
USE IN SPECIFIC POPULATIONS
Males of Reproductive Potential Based on animal studies, TALZENNA may impair fertility.
Renal Impairment The recommended dosage of TALZENNA for patients with moderate renal impairment (CLcr 30 – 59 mL/min) is 0.35 mg taken orally once daily with enzalutamide. The recommended dosage of TALZENNA for patients with severe renal impairment (CLcr 15 – 29 mL/min) is 0.25 mg taken orally once daily with enzalutamide. No dose adjustment is required for patients with mild renal impairment. TALZENNA has not been studied in patients requiring hemodialysis.
Please see full U.S. Prescribing Information and Patient Information for TALZENNA (talazoparib) at www.TALZENNA.com.
About XTANDI (enzalutamide)
XTANDI (enzalutamide) is an androgen receptor pathway inhibitor. XTANDI is a standard of care and has received regulatory approvals in one or more countries around the world for use in men with metastatic hormone-sensitive prostate cancer (mHSPC), metastatic castration-resistant prostate cancer (mCRPC), non-metastatic castration-resistant prostate cancer (nmCRPC) and non-metastatic hormone-sensitive prostate cancer (nmHSPC) with high-risk biochemical recurrence (BCR). XTANDI is currently approved for one or more of these indications in more than 80 countries, including in the United States, European Union and Japan. Over 1.5 million patients have been treated with XTANDI globally.7
About XTANDI (enzalutamide) and Important Safety Information
XTANDI (enzalutamide) is indicated for the treatment of patients with:
castration-resistant prostate cancer (CRPC)
metastatic castration-sensitive prostate cancer (mCSPC)
nonmetastatic castration sensitive prostate cancer (nmCSPC) with biochemical recurrence at high risk for metastasis (high-risk BCR)
Important Safety Information
Warnings and Precautions
Seizure occurred in 0.6% of patients receiving XTANDI in eight randomized clinical trials. In a study of patients with predisposing factors for seizure, 2.2% of XTANDI-treated patients experienced a seizure. It is unknown whether anti-epileptic medications will prevent seizures with XTANDI. Patients in the study had one or more of the following predisposing factors: use of medications that may lower the seizure threshold, history of traumatic brain or head injury, history of cerebrovascular accident or transient ischemic attack, and Alzheimer’s disease, meningioma, or leptomeningeal disease from prostate cancer, unexplained loss of consciousness within the last 12 months, history of seizure, presence of a space occupying lesion of the brain, history of arteriovenous malformation, or history of brain infection. Advise patients of the risk of developing a seizure while taking XTANDI and of engaging in any activity where sudden loss of consciousness could cause serious harm to themselves or others. Permanently discontinue XTANDI in patients who develop a seizure during treatment.
Posterior Reversible Encephalopathy Syndrome (PRES) There have been reports of PRES in patients receiving XTANDI. PRES is a neurological disorder that can present with rapidly evolving symptoms including seizure, headache, lethargy, confusion, blindness, and other visual and neurological disturbances, with or without associated hypertension. A diagnosis of PRES requires confirmation by brain imaging, preferably MRI. Discontinue XTANDI in patients who develop PRES.
Hypersensitivity reactions, including edema of the face (0.5%), tongue (0.1%), or lip (0.1%) have been observed with XTANDI in eight randomized clinical trials. Pharyngeal edema has been reported in post-marketing cases. Advise patients who experience any symptoms of hypersensitivity to temporarily discontinue XTANDI and promptly seek medical care. Permanently discontinue XTANDI for serious hypersensitivity reactions.
Ischemic Heart Disease In the combined data of five randomized, placebo-controlled clinical studies, ischemic heart disease occurred more commonly in patients on the XTANDI arm compared to patients on the placebo arm (3.5% vs 2%). Grade 3-4 ischemic events occurred in 1.8% of patients on XTANDI versus 1.1% on placebo. Ischemic events led to death in 0.4% of patients on XTANDI compared to 0.1% on placebo. Monitor for signs and symptoms of ischemic heart disease. Optimize management of cardiovascular risk factors, such as hypertension, diabetes, or dyslipidemia. Discontinue XTANDI for Grade 3-4 ischemic heart disease.
Falls and Fractures occurred in patients receiving XTANDI. Evaluate patients for fracture and fall risk. Monitor and manage patients at risk for fractures according to established treatment guidelines and consider use of bone-targeted agents. In the combined data of five randomized, placebo-controlled clinical studies, falls occurred in 12% of patients treated with XTANDI compared to 6% of patients treated with placebo. Fractures occurred in 13% of patients treated with XTANDI and in 6% of patients treated with placebo.
Embryo-Fetal Toxicity The safety and efficacy of XTANDI have not been established in females. XTANDI can cause fetal harm and loss of pregnancy when administered to a pregnant female. Advise males with female partners of reproductive potential to use effective contraception during treatment with XTANDI and for 3 months after the last dose of XTANDI.
Dysphagia or Choking Severe dysphagia or choking, including events that could be life-threatening requiring medical intervention or fatal, can occur due to XTANDI product size. Advise patients to take each capsule or tablet whole with a sufficient amount of water to ensure that all medication is successfully swallowed. Consider use of a smaller tablet size of XTANDI in patients who have difficulty swallowing. Discontinue XTANDI for patients who cannot swallow capsules or tablets.
Interference with Immunoassay Measurement of Digoxin XTANDI can interfere with certain digoxin immunoassays (e.g., Chemiluminescent Microparticle Immunoassays), resulting in falsely elevated digoxin plasma concentration results. Notify the laboratory conducting the digoxin plasma concentration assay to use an appropriate method in patients receiving XTANDI and digoxin.
Adverse Reactions (ARs)
In the data from the five randomized placebo-controlled trials, the most common ARs (≥ 10%) that occurred more frequently (≥ 2% over placebo) in XTANDI-treated patients were musculoskeletal pain, fatigue, hot flush, constipation, decreased appetite, diarrhea, hypertension, hemorrhage, fall, fracture, and headache. In the bicalutamide-controlled study, the most common ARs (≥ 10%) reported in XTANDI-treated patients were asthenia/fatigue, back pain, musculoskeletal pain, hot flush, hypertension, nausea, constipation, diarrhea, upper respiratory tract infection, and weight loss.
In EMBARK, the placebo-controlled study of nonmetastatic CSPC (nmCSPC) with high-risk biochemical recurrence (BCR) patients, Grade 3 or higher adverse reactions during the total duration of treatment were reported in 46% of patients treated with XTANDI plus leuprolide, 50% of patients receiving XTANDI as a single agent, and 43% of patients receiving placebo plus leuprolide. Permanent treatment discontinuation due to adverse reactions during the total duration of treatment as the primary reason was reported in 21% of patients treated with XTANDI plus leuprolide, 18% of patients receiving XTANDI as a single agent, and 10% of patients receiving placebo plus leuprolide.
Lab Abnormalities: Lab abnormalities that occurred in ≥ 5% of patients, and more frequently (> 2%) in the XTANDI arm compared to placebo in the pooled, randomized, placebo-controlled studies are hemoglobin decrease, neutrophil count decreased, white blood cell decreased, hyperglycemia, hypermagnesemia, hyponatremia, hypophosphatemia, and hypercalcemia.
Hypertension: In the combined data from five randomized placebo-controlled clinical trials, hypertension was reported in 14.2% of XTANDI patients and 7.4% of placebo patients. Hypertension led to study discontinuation in < 1% of patients in each arm.
Drug Interactions
Effect of Other Drugs on XTANDI Avoid coadministration with strong CYP2C8 inhibitors. If coadministration cannot be avoided, reduce the dosage of XTANDI. Avoid coadministration with strong CYP3A4 inducers. If coadministration cannot be avoided, increase the dosage of XTANDI.
Effect of XTANDI on Other Drugs Avoid coadministration with certain CYP3A4, CYP2C9, and CYP2C19 substrates for which minimal decrease in concentration may lead to therapeutic failure of the substrate. If coadministration cannot be avoided, increase the dosage of these substrates in accordance with their Prescribing Information. In cases where active metabolites are formed, there may be increased exposure to the active metabolites.
Please access this link for XTANDI’S US Full Prescribing Information for additional safety information.
(Press release, Pfizer, MAY 30, 2026, View Source [SID1234666281])