Pfizer breakthrough: New immunotherapy combo slashes bladder cancer recurrence risk by 32%

In a pivotal advancement for the bladder cancer treatment landscape, Pfizer Inc. (NYSE: PFE) announced on April 26, 2025, that its investigational therapy, sasanlimab, combined with standard Bacillus Calmette-Guérin (BCG) immunotherapy, achieved a statistically significant improvement in event-free survival (EFS) for patients with BCG-naïve, high-risk non-muscle invasive bladder cancer (NMIBC). Data from the Phase 3 CREST trial revealed a 32% reduction in the risk of disease-related events, such as high-grade disease recurrence or progression, compared to BCG standard of care alone.

This clinical milestone marks the first major potential treatment advancement in more than three decades for patients newly initiating BCG therapy. Pfizer has shared these findings with global health regulators, aiming to support upcoming regulatory submissions that could change the standard of care in NMIBC.

What Were the Key Findings from the Phase 3 CREST Trial?

The CREST trial achieved its primary endpoint of event-free survival, with investigator assessments showing a hazard ratio (HR) of 0.68 (95% Confidence Interval [CI]: 0.49-0.94; p=0.019). Median EFS had not yet been reached at the time of the announcement. Subgroup analyses demonstrated consistent benefits across different patient profiles, including an EFS HR of 0.63 for patients with T1 disease and 0.53 for those with carcinoma in situ (CIS).

EFS was defined as the time from randomization to the earliest occurrence of high-grade disease recurrence, disease progression, persistent CIS, or death. At 36 months, 82.1% of patients receiving the sasanlimab plus BCG induction and maintenance regimen remained event-free, compared to 74.8% of patients on BCG alone.

These breakthrough results were presented during a plenary session at the 2025 American Urological Association (AUA) Annual Meeting, solidifying Pfizer’s potential lead in early-stage bladder cancer innovation.

Why Is Sasanlimab a Potential Game-Changer in Bladder Cancer Treatment?

Sasanlimab is a subcutaneously administered, investigational anti-PD-1 monoclonal antibody designed to inhibit immune checkpoints that cancers often exploit to evade immune responses. Administered once every four weeks via a prefilled syringe, sasanlimab offers a patient-friendly delivery option compared to traditional intravenous therapies.

According to Neal Shore, M.D., FACS, Medical Director for START Carolina Research Center and lead investigator for the CREST trial, combining sasanlimab with BCG earlier in the disease course significantly prolonged event-free survival. Shore emphasized that after decades of relying solely on BCG therapy — which fails in nearly half of high-risk NMIBC cases — these results could redefine how early-stage bladder cancer is managed, providing patients with a much-needed new treatment alternative.

How Did Sasanlimab Perform in Secondary Endpoints?

Although sasanlimab in combination with BCG induction only (without maintenance) did not show EFS improvement over standard BCG induction and maintenance therapy (HR 1.16; p=0.312), the full induction-plus-maintenance regimen demonstrated substantial benefit.

Importantly, complete response (CR) rates for patients with CIS at randomization were encouraging. A CR was achieved in 89.8% of patients in the sasanlimab-BCG (induction and maintenance) arm versus 85.2% with BCG alone. Among those who achieved CR, 91.7% remained disease-free at 36 months when treated with sasanlimab and BCG, compared to 67.7% with BCG alone, underscoring a potentially durable benefit.

An early interim analysis of overall survival (OS) suggested no difference between arms at a median follow-up of 40.9 months, and the study remains ongoing for survival evaluation.

What Is the Safety Profile of the Sasanlimab and BCG Combination?

Pfizer reported that the safety profile of the sasanlimab-BCG combination was consistent with known data from BCG therapy and prior clinical studies of PD-1 inhibitors. No new safety concerns emerged, reinforcing the potential for sasanlimab to become a well-tolerated option in high-risk NMIBC management.

The tolerability, combined with the convenience of a subcutaneous injection, could position sasanlimab as an attractive addition to BCG therapy for both physicians and patients.

How Does Bladder Cancer Impact Patients Globally?

Bladder cancer remains the ninth most common cancer worldwide, responsible for approximately 220,000 deaths each year. Non-muscle invasive bladder cancer accounts for around 75% of bladder cancer cases. In the United States alone, about 38,000 patients live with high-risk NMIBC, a group that has historically faced limited innovation beyond BCG intravesical immunotherapy since its introduction decades ago.

Despite BCG’s ability to reduce tumor recurrence risks, 40-50% of patients experience recurrence or disease progression, creating a significant unmet need for improved therapies.

How Are Investors Reacting to Pfizer’s Oncology Pipeline Progress?

Pfizer’s announcement of the CREST trial success is seen positively by the market, particularly as the company seeks to diversify and strengthen its post-pandemic revenue streams. Pfizer shares (NYSE: PFE) traded higher in pre-market activity following the data release, suggesting investor confidence in the Oncology division’s innovation pipeline.

With sasanlimab offering a differentiated mechanism and convenient delivery platform, analysts view the drug as a strong candidate for future regulatory approval and commercial success in a market underserved by new therapies. Institutional investor sentiment towards Pfizer’s Oncology division has remained stable, with buy-side positioning expecting accelerated revenue contributions from immunotherapy pipelines.

Future approvals, especially in indications with high unmet need like NMIBC, are expected to significantly bolster Pfizer’s growth trajectory over the next five years.

What’s Next for Sasanlimab and Pfizer?

Pfizer has submitted the CREST data to health authorities globally to support regulatory filings for sasanlimab in combination with BCG for BCG-naïve, high-risk NMIBC. Regulatory decisions are anticipated within the next 12 to 18 months, depending on review timelines.

Beyond bladder cancer, sasanlimab is under investigation across multiple ongoing trials, including combinations with Pfizer’s antibody-drug conjugate (ADC) portfolio in broader urothelial and solid tumor indications, reinforcing Pfizer Oncology‘s ambition to lead the next generation of immunotherapy.

As Megan O’Meara, M.D., Interim Chief Development Officer at Pfizer Oncology, noted, the CREST trial results not only represent a significant scientific breakthrough but also underscore Pfizer’s commitment to delivering transformative therapies that meaningfully extend and improve lives across all stages of cancer.