Breast cancer treatments heat up: Six therapies poised to transform patient outcomes

According to the World Health Organization (WHO), breast cancer was the most common cancer in women in 157 countries out of 185 in 2022, with incidence rates found to be rising by 1% per year overall – and 1.4% per year for women under the age of 50. Fortunately, however, deaths from breast cancer have dropped by around 10% in the past decade. There is a direct link between this statistic and the wide array of new breast cancer treatments that have become available on the market. 

In fact, when Phesi released the results of its annual global analysis of all clinical trials conducted in 2025, it showed that breast cancer was once again the world’s most studied disease for the fifth consecutive year, demonstrating the interest in this indication from big pharma and biotech companies.  

In this article, we explore the breast cancer treatment landscape, with a particular focus on several biotech companies that have received positive results in the last year for their respective therapies.  

Breast cancer: A broad treatment landscape with an established market 

Breast cancer is a heterogeneous disease that encompasses several different subtypes defined by distinct molecular profiles, behaviors, and responses to treatment.  

In breast cancer, the cancer cells can either have estrogen receptors (ER) or progesterone receptors (PR), which basically means that the cells have receptors that allow them to use either estrogen or progesterone to grow. Approximately 75% of breast cancers are estrogen receptor-positive (ER+).  

In addition to this, the cancer can either be HER2-positive or HER2-negative; HER2 is a protein that helps breast cancer cells grow quickly. Meanwhile, triple-negative breast cancer means the cancer cells do not have ER or PR receptors, and do not make any or too much HER2. This type of breast cancer tends to grow or spread faster and comes with fewer treatment options.  

This diversity has led to a complex treatment landscape, with companies adopting several different approaches to tackling breast cancer.  

There are already a variety of approved products on the market to tackle the challenges of this diversity, with several of these therapies now forming the cornerstone of breast cancer treatment. Targeted treatments like Roche’s trastuzumab (Herceptin) have transformed outcomes for patients with HER2-positive breast cancer. Similarly, Pfizer’s palbociclib (Ibrance), a CDK4/6 inhibitor, has become a standard for managing HR+, HER2-negative advanced breast cancer, and AstraZeneca’s olaparib (Lynparza), a poly ADP-ribose polymerase (PARP) inhibitor, provides an option for patients with inherited breast cancer gene (BRCA) mutations. Most recently, Eli Lilly’s oral selective oestrogen receptor degrader (SERD) therapy, imlunestrant, also received approval, giving patients an additional option for ER-positive, HER2-negative, ESR1-mutated advanced or metastatic breast cancer.  

Nevertheless, many companies are still working toward bringing more new therapies to the market in an effort to broaden the treatment landscape even further, in turn providing a vast array of options for patients – even those who find their cancers resistant to treatment with current standard of care therapies.  

New technologies related to breast cancer

• NP-Based Combinatorial Breast Cancer Therapy – The American University in Cairo
• MUC1 Cancer Antibody – The University of North Carolina at Charlotte
• Novel Small Molecule Inhibits Metastatic Breast Cancer – Puerto Rico Science, Technology & Research Trust

Roche reports another phase 3 win for oral SERD therapy giredestrant 

In December 2025, Roche announced more detailed data behind its second phase 3 win for its oral SERD therapy, giredestrant, reporting that the drug reduced the risk of invasive disease recurrence or death by 30% in ER-positive early-stage breast cancer.  

In the trial, named lidERA, the drug was being studied as an adjuvant endocrine treatment for people with ER-positive, human epidermal growth factor receptor 2-negative, early-stage breast cancer, and the big pharma said that it is the first and only oral SERD to show superior invasive disease-free survival (iDFS) in the adjuvant setting.  

SERD therapies are endocrine therapies that bind to and break down ERs, which are found inside the cells of female reproductive tissue, breast tissue, other types of tissue, and some cancer cells. These drugs keep the hormone estrogen from binding to the ERs inside the cells and block the effects of estrogen in the body, stopping the cancer cells from growing. 

The first-ever approval for an oral SERD for breast cancer came in 2023 when the FDA approved Menarini’s Orserdu (elacestrant) for postmenopausal women or adult men with ER-positive, HER2-negative, ESR1-mutated advanced or metastatic breast cancer with disease progression following at least one line of endocrine therapy. Since then, big pharma has been competing to bring more effective SERD therapies to the market. 

As lidERA was the second positive phase 3 readout for giredestrant following the evERA breast cancer results in the metastatic setting, the drug is now positioned for regulatory filings, and Roche could potentially become the first company to establish an oral SERD therapy in the adjuvant market.  

On a call with journalists in January, Roche’s chief executive officer (CEO), Thomas Schinecker, even said that the breast cancer drug could become the company’s biggest-selling medicine. 

AstraZeneca’s SERD therapy also shows significant promise in breast cancer treatment 

In late February 2025, AstraZeneca’s SERD breast cancer drug, camizestrant, also produced significant results, demonstrating a highly statistically significant and clinically meaningful improvement in the primary endpoint of progression-free survival in HR-positive breast cancer patients when tested in combination with a cyclin-dependent kinase (CDK) 4/6 inhibitor in a phase 3 trial. This made it the first and only next-generation oral SERD and complete estrogen receptor (ER) antagonist to demonstrate first-line benefit in combination with widely approved CDK4/6 inhibitors. 

The study also featured a novel design that reflected an unmet need in the indication, whereby physicians monitored circulating tumor DNA to spot ESR1 mutations, which can make the cancer resistant to treatment. If a mutation was found in the trial before disease progression, patients switched to camizestrant and stayed on the CDK4/6 drug.  

Further phase 3 data announced by AstraZeneca in June linked camizestrant to an impressive 56% reduction in the risk of disease progression or death in patients with advanced HR-positive breast cancer with an emergent ESR1 tumour mutation.  

Based on these positive results, camizestrant in combination with a CDK4/6 inhibitor has been granted breakthrough therapy designation in the U.S. for the treatment of adult patients with HR-positive, HER2-negative, locally advanced or metastatic breast cancer upon emergence of ESR1 mutation during first-line endocrine-based therapy. 

BioNTech provides evidence that its bispecific breast cancer treatment can unseat Keytruda 

Through its $800 million acquisition of Biotheus, BioNTech gained full control of a candidate that has the potential to unseat Merck’s checkpoint inhibitor Keytruda to become the new standard of care in multiple cancer indications, including breast cancer. The acquisition followed a strategic partnership with Biotheus in 2023, in which BioNTech paid $55 million upfront for the rights to the candidate outside of greater China.  

The candidate in question is a bispecific antibody called BNT327 that targets both PD-L1 and VEGF-A. Essentially, it combines PD-L1 checkpoint inhibition, which is aimed at restoring the T cells’ ability to recognize and destroy tumor cells, with the neutralization of VEGF-A. The blocking of VEGF-A is aimed at reversing the tumor’s immuno-suppressive effect in its microenvironment and cutting off the blood and oxygen supply that feeds tumor cells, with the intention of preventing tumor growth and proliferation.  

When Akeso and Summit Therapeutics’ own PD-1xVEGF-A candidate ivonescimab beat Keytruda in September last year, it spearheaded the belief that this new class of drug can be more effective than traditional checkpoint inhibitors and replace several blockbuster therapies that are currently the mainstay in many cancer regimens. The possibilities presented by this are likely what increased BioNTech’s willingness to bet even further on BNT327 in its acquisition of Biotheus.  

In December 2024, BioNTech added to the evidence that these bispecifics really can unseat Keytruda, reporting positive results from a trial run by Biotheus in patients with locally advanced or metastatic triple-negative breast cancer who took BNT327 and nab-paclitaxel as a first-line therapy. Researchers shared the first look at overall survival data from the trial at the San Antonio Breast Cancer Symposium, showing an 18-month overall survival rate of 69.7%. This was compared to Merck’s KEYNOTE-355 trial, which reported an estimated overall survival at 18 months of 47.8% in triple-negative breast cancer patients who received Keytruda and chemotherapy.  

Furthermore, in June 2025, the drug attracted interest from big pharma, with Bristol Myers Squibb entering into a strategic partnership with BioNTech to co-develop and co-commercialize BNT327 for multiple solid tumor types. Then, in December, the two companies announced that interim phase 2 data in locally advanced/metastatic triple-negative breast cancer showed encouraging antitumor activity for BNT327plus chemotherapy in first- and second-line patients.  

A phase 3 trial is now evaluating the drug plus chemotherapy versus placebo plus chemotherapy in patients with previously untreated locally advanced/metastatic triple-negative breast cancer determined ineligible for PD-(L)1 therapy. Meanwhile, the candidate is also being studied in more than 20 clinical trials as a monotherapy, in combination with chemotherapy, or with other novel treatment modalities in more than 10 solid tumor indications. 

Carrick Therapeutics announces positive phase 2 results for CDK7 inhibitor samuraciclib 

Samuraciclib is an oral CDK7 inhibitor being developed by Carrick Therapeutics for advanced HR+, HER2-negative breast cancer who were previously treated with a CDK4/6 inhibitor therapy.  

Inhibiting CDK7 is a promising therapeutic strategy in cancer, as CDK7 regulates the transcription of cancer-causing genes, promotes uncontrolled cell cycle progression, and promotes resistance to anti-hormone therapy. 

Carrick announced positive results for the candidate from its phase 2 SUMIT-BC trial, which were presented at the 2025 San Antonio Breast Cancer Symposium in December 2025. The combination of samuraciclib with AstraZeneca’s fulvestrant showed encouraging outcomes: the overall response rate reached 33% with a median progression-free survival of 7.8 months, outperforming fulvestrant alone, and in patients without TP53 gene mutations, the overall response rate was 55% with a median progression-free survival of 14.5 months, suggesting substantially improved disease control in this biomarker-defined subgroup.  

Samuraciclib has been granted fast track designation by the U.S. Food and Drug Administration (FDA) and is set for a phase 3 trial in 2026.  

Coud Relay Therapeutics’ PI3Kα inhibitor challenge AstraZeneca’s Truqap? 

Relay Therapeutics’ candidate for breast cancer treatment is a phosphoinositide 3-kinase alpha (PI3Kα) inhibitor called RLY-2608 that is designed to target and inhibit only the mutant form of PI3Kα so that it spares the normal enzyme in the hope of minimizing off-target effects and reducing toxicity. 

The reason that Relay is targeting PI3Kα is because it is a critical enzyme involved in cancer cell growth and survival. Mutations in the PIK3CA gene – which encodes the PI3Kα enzyme – are some of the most common genetic alterations in HR+, HER2-negative metastatic breast cancer, leading to hyperactivation of the PI3K pathway, in turn driving tumor proliferation and resistance to standard therapies.  

In September 2024, Relay Therapeutics reported that, according to interim data from a phase 2 trial, it had beaten its survival goal for RLY-2608. The study, which tested the candidate in combination with fulvestrant, demonstrated a median progression-free survival of 9.2 months in patients with heavily pre-treated PI3Kα-mutated, HR+/HER2- metastatic breast cancer.  

According to Fierce Biotech, ahead of the readout, Relay identified the 5.5-month progression-free survival seen in a study of AstraZeneca’s Truqap as the benchmark for its trial. Although cross-trial comparisons can be unreliable, the almost four-month difference between the progression-free survival reported between RLY-2608 and Truqap means that Relay’s candidate could become a challenger to Truqap if it continues to demonstrate the same kind of data in later pivotal trials.   

The drug is now being tested in a phase 3 study. In December 2025, Relay announced at the 2025 San Antonio Breast Cancer Symposium (SABCS) that efficacy data for the candidate remain consistent with previous disclosures, showing 10.3-month median progression-free survival in all patients and 11.4-month median progression-free survival in second-line patients. Additionally, a subset analysis showed broad activity in patients with PI3Kα-mutated, HR+/HER2- metastatic breast cancer, regardless of prior fulvestrant or other SERD exposure, or ESR1 mutation status.  

Olema Pharmaceuticals presents promising new breast cancer treatment data for small molecule OP-1250  

Olema Pharmaceuticals is a breast cancer-focused biotech company whose lead candidate, palazestrant (OP-1250), is a small molecule that works as both a complete estrogen receptor antagonist (CERAN) and a SERD. The dual mechanism here is designed to inhibit and degrade the estrogen receptor, with the aim of effectively blocking the estrogen signaling pathways that drive the growth of ER-positive, HER2-negative breast cancer cells. 

After sharing positive phase 1b/2 interim data in May 2023 for palazestrant showing that it exhibited favorable pharmacokinetics, tolerability, and preliminary anti-tumor activity in patients with recurrent, locally advanced, or metastatic ER-positive, HER2-negative breast cancer, Olema presented more promising new data in October 2025 at the European Society for Medical Oncology (ESMO) Congress, demonstrating that the drug, in combination with ribociclib, demonstrated encouraging activity across all dose cohorts and subgroups, with a median progression-free survival of 15.5 months in the 120mg cohort across all patients. 

The candidate is currently being evaluated as a single agent in an ongoing pivotal phase 3 trial, OPERA-01, and in combination with ribociclib in another ongoing pivotal phase 3 study, OPERA-02, for the treatment of breast cancer.  

Breast cancer: A challenging indication  

The sheer diversity of breast cancer and its different subtypes represents serious challenges for biotech companies.  

Resistance to endocrine therapies, targeted therapies, and chemotherapy continues to limit long-term efficacy for many patients. Furthermore, triple-negative breast cancer remains a critical unmet need due to the lack of hormone or HER2 targets, making it a more aggressive and difficult-to-treat subtype that results in more deaths.  

Yet the future of breast cancer treatment is a hopeful one, as more and more therapies with varying targets and functionality work their way toward regulatory approval. Additionally, the potential of certain combination therapies means that carefully put together treatment regimens should be able to tackle the heterogeneity of breast cancer.  

Ultimately, the goal is for patients with any subtype of breast cancer to have a fighting chance of kicking their disease into remission.