A PHASE 1, NON-RANDOMIZED, OPEN-LABEL, SINGLE-DOSE, PARALLEL GROUP STUDY TO COMPARE THE PHARMACOKINETICS OF ATIRMOCICLIB IN ADULT PARTICIPANTS WITH VARYING DEGREES OF HEPATIC IMPAIRMENT RELATIVE TO PARTICIPANTS WITH NORMAL HEPATIC FUNCTION

The purpose of this study to understand how the study medicine atirmociclib behaves in the body and how safe it is for people with different levels of liver health.
The study is seeking participants who are:
* Aged 18 years or older
* Have a BMI of 17.5 to 40 kg/m2, and body weight more than 50 kg.
* Have normal liver function or have stable mild, moderate, or severe liver disease
Participants will receive study medicine by mouth. Blood samples will be collected to see how much of the medicine is in the body over time. This will help understand whether liver disease changes how the medicine is handled.
Participants will be in the study for about 9 weeks. Those with normal liver function will stay in the clinic for about 7 days. People with liver disease will stay for about 9 days. After leaving the clinic, people may be contacted for follow-up. This may be done by phone or through a clinic visit.

Start Date09 Jul 2026

Sponsor / Collaborator

Pfizer Inc.

NCT07427394

/ RecruitingPhase 2

A Phase IIa, Open-label Study to Evaluate the Safety, Pharmacokinetics and Preliminary Efficacy of Camizestrant in Combination With Atirmociclib in Participants With ER-positive, HER2-negative Advanced Breast Cancer (SERENA-1b)

A study to investigate camizestrant in combination with atirmociclib in participants with estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer previously treated with a cyclin dependent kinase 4/6 (CDK4/6) inhibitor.

Start Date06 May 2026

Sponsor / Collaborator

AstraZeneca PLC

NCT07215078

/ RecruitingPhase 1

A PHASE 1, OPEN-LABEL, TWO-PERIOD, CROSS-OVER STUDY TO EVALUATE DOSE PROPORTIONALITY OF ATIRMOCICLIB (PF-07220060) PHARMACOKINETICS WHEN ADMINISTERED UNDER FED CONDITIONS TO HEALTHY PARTICIPANTS

The purpose of this clinical trial is to learn about the dose proportionality on the PK of the study medicine (called atirmociclib) when administered in the various doses range under the fed condition in healthy participants.
This study is seeking participants who are:
1. male and female aged 18 to 65 years are healthy as determined by medical evaluation including medical history, physical examination, and laboratory tests
2. with BMI of 17.5-30.5 kg/m2; and a total body weight >50 kgs (110 lbs.).
All participants (72 total) in this study will receive atirmociclib at Dose (A), Dose (B), Dose (C), and Dose (D) oral dose in 1 of the 12 treatment sequences among 6 cohorts under fed conditions.
Atirmociclib will be given by mouth at the study research unit once single dose about 30 minutes after a moderate fat standard calorie meal.
Dose proportionality will be evaluated on the pharmacokinetics (PK), safety and tolerability of atirmociclib at Doses (A), (B), (C), and (D) oral dose under the fed condition.
Including the 28 days of screening window and the 35 days safety follow-up period, the total study duration for each participant can be up to 71 days, containing 2 periods (6 days for each period), minimum 7-day interval between two periods, and follow-up period 28 to 35 days from administration of the final dose of study intervention. During this time, they will undergo safety laboratory and serial blood PK samplings up to 120 hours after administration of atirmociclib to determine plasma concentrations of atirmociclib. Participants will be discharged from the research unit on Period 2 Day 6 following completion of all assessments.

Start Date08 Oct 2025

Sponsor / Collaborator

Pfizer Inc.

100 Clinical Results associated with Atirmociclib

100 Translational Medicine associated with Atirmociclib

100 Patents (Medical) associated with Atirmociclib

Literatures (Medical) associated with Atirmociclib

01 May 2026·JOURNAL OF CHROMATOGRAPHY B-ANALYTICAL TECHNOLOGIES IN THE BIOMEDICAL AND LIFE SCIENCES

Identification and characterization of atirmociclib metabolites through high resolution-mass spectrometry-based in vitro and in vivo rat biological sample analysis

Article

Author: Nandi, Sukhendu ; Pawar, Swati Ramesh ; Loganathan, Gayathri ; Srikanth, Pirangi ; Biradar, Rushikesh ; Kumar, Deepak ; Shaik, Khaja Moinuddin

Cancer continues to be one of the foremost causes of global morbidity and mortality, underscoring the urgent need for innovative therapeutic agents. Atirmociclib, a selective cyclin-dependent kinase 4 (CDK4) inhibitor, is currently being explored for its remarkable anticancer potential. Although its pharmacological profile is promising, there remains a scarcity of data regarding its metabolic pathway. This study seeks to provide a detailed characterization of the in vitro and in vivo metabolism of atirmociclib, utilizing human liver microsomes (HLM), rat liver microsomes (RLM), and HS9 fractions, alongside female Sprague-Dawley rats as the in vivo model. Employing high-resolution LC-ESI-Q-TOF-MS/MS for metabolite profiling in rat plasma, urine, and feces, we identified and structurally elucidated a total of seven novel phase I and phase II metabolites based on accurate mass measurements and their fragmentation patterns. Notable biotransformation pathways include N-dealkylation, hydroxylation, oxidation, dihydroxylation, sulfate conjugation, and glucuronidation. In silico toxicity predictions classified atirmociclib and its metabolites within class 4 (predicted LD₅₀: 1000-2000 mg/kg), suggesting low acute toxicity while highlighting potential risks such as neurotoxicity, respiratory toxicity, and immunogenicity. This research article is the first time to discuss the complete metabolite profiling including identification and characterization of atirmociclib metabolites as well as its biotransformation mechanism. ABBREVATIONS.

25 Dec 2025·JOURNAL OF MEDICINAL CHEMISTRY

Discovery of Atirmociclib (PF-07220060): A Potent and Selective CDK4 Inhibitor

Article

Author: Kania, Robert ; Boras, Britton ; Kath, John C. ; Cianfrogna, Julie A. ; Wei, Na ; Ninkovic, Sacha ; Deal, Judith G. ; Gallego, Gary M. ; Dress, Klaus ; Lafontaine, Jennifer ; Shen, Hong ; Pascual, Bernadette ; Cho-Schultz, Sujin ; Johnson, Eric ; Cox, Loretta ; Marroquin, Lisa ; Orr, Suvi ; Anders, Lars ; Quinlan, Casey ; Sach, Neal ; Edwards, Martin ; Jalaie, Mehran ; Cao, Fengjuan ; Petroski, Matthew ; Chen, Ping ; Bernier, Louise ; Palmer, Cynthia ; Sacaan, Aida ; Nair, Sajiv K.

Inhibitors of cyclin-dependent kinases 4 and 6 have been shown to be clinically effective for the treatment of hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced, or metastatic breast cancer. These agents, however, often show neutropenia, likely due to the role of CDK6 in hematopoiesis. Herein described is the discovery of a series of aminopyrimidine-based selective CDK4 inhibitors. Central to our strategy were efficiency-based optimization (LipE and LipMetE), structure-based drug design, and molecular dynamics simulation. The culmination of these efforts resulted in the discovery of PF-07220060 (atirmociclib), which possessed high potency and levels of selectivity for CDK4 over CDK6 that translated to minimal impact on neutrophils while driving efficacy in a mouse ZR75-1 xenograft model.

01 Oct 2025·JOURNAL OF MOLECULAR BIOLOGY

Distinct Allosteric Networks in CDK4 and CDK6 in the Cell Cycle and in Drug Resistance

Article

Author: Kõivomägi, Mardo ; Nussinov, Ruth ; Liu, Yonglan ; Heidebrink, Gretchen ; Bradburn, Devin ; Jang, Hyunbum ; Zhang, Wengang

Cyclin-dependent kinases 4 and 6 (CDK4 and CDK6) are key regulators of the G₁-S phase transition in the cell cycle. In cancer cells, CDK6 overexpression often outcompetes CDK4 in driving cell cycle progression, contributing to resistance against CDK4/6 inhibitors (CDK4/6i). This suggests distinct functional and conformational differences between these two kinases, despite their striking structural and sequence similarities. Understanding the mechanisms that differentiate CDK4 and CDK6 is crucial, as resistance to CDK4/6i-frequently linked to CDK6 overexpression-remains a significant therapeutic challenge. Notably, CDK6 is often upregulated in CDK4/6i-resistant cancers and rapidly proliferating hematopoietic stem cells, underscoring its unique regulatory roles. We hypothesize that their distinct conformational dynamics explain their differences in phosphorylation of retinoblastoma protein, Rb, inhibitor efficacy, and cell cycle control. This leads us to question how their dissimilar conformational dynamics encode their distinct actions. To elucidate their differential activities, molecular mechanisms, and inhibitor binding, we combine biochemical assays and molecular dynamics (MD) simulations. We discover that CDK4 and CDK6 have distinct allosteric networks connecting the β3-αC loop and the G-loop. CDK6 exhibits stronger coupling and shorter path lengths between these regions, resulting in higher kinase activity upon cyclin binding and impacting inhibitor specificity. We also discover an unrecognized role of the unstructured CDK6 C-terminus, which allosterically connects and stabilizes the R-spine, facilitating slightly higher activity. Our findings bridge the gap between the structural similarity and functional divergence of CDK4 and CDK6, advancing the understanding of kinase regulation in cancer biology.

News (Medical) associated with Atirmociclib

06 Aug 2026

·www.biospace.com

Relay Therapeutics Reports Second Quarter 2026 Financial Results and Corporate Updates

Selected z ovegalisib plus atirmociclib as go-forward triplet regimen for 1L breast cancer; Phase 3 1L trial in endocrine - sensitive patients expected to initiate in early 2027, subject to regulatory feedback Presented initial positive clinical data from Phase 1/2 ReInspire trial in vascular anomalies at the ISSVA World Congress 2026 and opened expansion cohorts Continued execution of ongoing Phase 3 ReDiscover-2 trial in 2L breast cancer Approximately $911 million in cash, cash equivalents and investments at end of Q2 2026 ezstandalone.cmd.push(function () { ezstandalone.showAds(131); }); CAMBRIDGE, Mass., Aug. 06, 2026 (GLOBE NEWSWIRE) -- Relay Therapeutics, Inc. (Nasdaq: RLAY), a clinical-stage, small molecule precision medicine company developing potentially life-changing therapies for patients living with cancer and genetic disease, today reported second quarter 2026 financial results and corporate updates. “The second quarter marked continued momentum across our zovegalisib program, with advances in our frontline breast cancer development strategy and the presentation of initial clinical data at ISSVA 2026 for zovegalisib in patients with vascular anomalies,” said Sanjiv Patel, M.D., President and Chief Executive Officer of Relay Therapeutics. “This progress, including the ongoing Phase 3 trial in second-line breast cancer and the triplet combination work to support development in frontline breast cancer, reinforces the promise of mutant-selective PI3Kα inhibition and strengthens our confidence in zovegalisib's potential across multiple patient populations. Supported by a strong cash position with expected runway into 2029, we continue to focus on the execution of several clinical and regulatory milestones expected for zovegalisib this year as we work to develop potentially life-changing therapies for patients living with cancer and genetic disease.” Corporate Highlights Second-line (2L) Breast Cancer Continued to execute on the Phase 3 ReDiscover-2 trial of zovegalisib + fulvestrant in PI3Kα-mutated, CDK4/6 pre-treated, HR+/HER2- advanced breast cancer Front-line (1L) Breast Cancer Announced clinical data for zovegalisib plus atirmociclib triplet combination, plans for 1L breast cancer study, and clinical supply agreement with Pfizer Compelling efficacy and tolerability data presented for zovegalisib triplet in median third-line (3L) patients with PI3Kα-mutated, HR+/HER2- metastatic breast cancer 44% objective response rate (ORR) reported in heavily pre-treated CDK4/6-experienced patients (median 3L) at unoptimized doses and ORR was similar across kinase and non-kinase PIK3CA mutations Adverse events were consistent with those previously reported by each molecule Phase 3 1L trial in patients with endocrine-sensitive breast cancer expected to initiate in early 2027, subject to regulatory feedback Pfizer agreed to supply atirmociclib for the experimental arm and the palbociclib portion of the control arm for use in the planned study, and Relay will retain full global rights for zovegalisib Continued to execute the Phase 1/2 ReDiscover trial, advancing the ongoing triplet cohorts with zovegalisib + atirmociclib + endocrine therapy Vascular Anomalies Presented initial clinical data from the Phase 1/2 ReInspire trial of zovegalisib in vascular anomalies at the International Society for the Study of Vascular Anomalies (ISSVA) World Congress 2026 In the Part 1 dose randomization portion of the study for adults and adolescents ages 12 and up, 60% of patients achieved a volumetric response at the earliest time point (12 weeks) Nearly all patients experienced symptomatic improvement at 12 weeks while maintaining a safety and tolerability pro the potential for chronic use Opened expansion cohorts for adults and adolescents and continued dose escalation for pediatric patients age 6-11 in the Phase 1/2 ReInspire trial to further evaluate zovegalisib in patients with PIK3CA-driven vascular anomalies NRAS Selective Inhibitor: RLY-8161 Continued execution of the Phase 1/2 clinical trial for RLY-8161, a NRAS-selective inhibitor, in patients with NRAS-mutant melanoma and other NRAS-mutant solid tumors Corporate Raised approximately $316 million of gross proceeds in an underwritten follow-on public offering in May 2026 Anticipated Milestones: Breast Cancer Enrollment update for ongoing Phase 3 ReDiscover-2 trial in 2L breast cancer by year-end 2026 Regulatory update to confirm design for planned Phase 3 trial in 1L endocrine sensitive breast cancer by year-end 2026 Data update for Phase 1/2 triplet combination in 1H 2027 Vascular Anomalies Data and regulatory update by year-end 2026 Second Quarter 2026 Financial Results Cash, Cash Equivalents and Investments: As of June 30, 2026, cash, cash equivalents and investments totaled $910.9 million, as compared to $642.1 million as of March 31, 2026. The increase in cash is primarily due to net proceeds from the underwritten follow-on public offering in May 2026. The company expects its current cash, cash equivalents, and investments will be sufficient to fund its operating expenses and capital expenditure requirements into 2029. Revenue: Revenue was $0.4 million for the second quarter of 2026, as compared to $0.7 million for the second quarter of 2025. The revenue recognized in each period was under the company's Exclusive License Agreement with Elevar Therapeutics, Inc. R&D Expenses: Research and development expenses were $76.5 million for the second quarter of 2026, as compared to $63.9 million for the second quarter of 2025. The increase of $12.6 million was primarily due to increases in costs across ongoing clinical trials for zovegalisib, partially offset by the impact from strategic choices made to streamline the research organization prior to 2026. G&A Expenses: General and administrative expenses were $14.7 million for the second quarter of 2026, as compared to $13.6 million for the second quarter of 2025. The increase of $1.1 million was primarily due to increased legal expenses, offset by decreases in employee compensation costs, including stock compensation expense. Net Loss: Net loss was $83.7 million for the second quarter of 2026, or a net loss per share of $0.41, as compared to a net loss of $70.4 million for the second quarter of 2025, or a net loss per share of $0.41. About Zovegalisib Zovegalisib is the lead program in Relay Therapeutics’ efforts to discover and develop mutant-selective inhibitors of PI3Kα, the most frequently mutated kinase in all cancers and all vascular anomalies. Zovegalisib has the potential, if approved, to address a significant portion of the approximately 140,000 patients with HR+/HER2- breast cancer with a PI3Kα mutation and the estimated 170,000 patients with vascular anomalies driven by a PI3Kα mutation per year in the United States, one of the largest patient populations for a precision medicine. Traditionally, the development of PI3Kα inhibitors has focused on the active, or orthosteric, site. The therapeutic index of orthosteric inhibitors is limited by the lack of clinically meaningful selectivity for mutant versus wild-type (WT) PI3Kα and off-isoform activity. Toxicity related to inhibition of WT PI3Kα and other PI3K isoforms results in sub-optimal inhibition of mutant PI3Kα with reductions in dose intensity and frequent discontinuation. The Dynamo® platform enabled the discovery of zovegalisib, the first known allosteric, pan-mutant, and isoform-selective PI3Kα inhibitor, designed to overcome these limitations. Relay Therapeutics solved the full-length cryo-EM structure of PI3Kα, performed computational long time-scale molecular dynamic simulations to elucidate conformational differences between WT and mutant PI3Kα, and leveraged these insights to support the design of zovegalisib. Zovegalisib is currently being evaluated in multiple metastatic breast cancer studies and a Phase 1/2 study designed to treat patients with PIK3CA (PI3Kα) mutation-driven vascular anomalies. For more information on zovegalisib, please visit here . About Relay Therapeutics Relay Therapeutics (Nasdaq: RLAY) is a clinical-stage, small molecule precision medicine company developing potentially life-changing therapies for patients living with cancer and genetic disease. Relay Therapeutics’ Dynamo® platform integrates an array of leading-edge computational and experimental approaches designed to drug protein targets that have previously been intractable or inadequately addressed. Relay Therapeutics’ lead clinical asset, zovegalisib, is the first pan-mutant selective PI3Kα inhibitor to enter clinical development and is currently in a Phase 3 clinical trial (ReDiscover-2) in HR+/HER2- metastatic breast cancer. Zovegalisib is also being investigated in a group of genetic disease indications called PI3Kα-driven vascular anomalies. Relay Therapeutics’ pipeline also includes programs for NRAS-driven solid tumors and Fabry disease. For more information, please visit or follow us on LinkedIn . Cautionary Note Regarding Forward-Looking Statements This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended, including, without limitation, implied and express statements regarding Relay Therapeutics’ strategy, business plans and focus; the progress and timing of the clinical development of the programs across Relay Therapeutics’ portfolio, including zovegalisib and RLY-8161; the timing of clinical data readouts for zovegalisib; the expected therapeutic benefits and potential efficacy and tolerability of zovegalisib, both as a monotherapy and in combination with other agents, and its other programs; the clinical data for zovegalisib; the interactions with regulatory authorities and any related approvals; the potential commercialization and market opportunity for zovegalisib; and the cash runway projection and the expectations regarding Relay Therapeutics’ use of capital and expenses. The words “may,” “might,” “will,” “could,” “would,” “should,” “plan,” “anticipate,” “intend,” “believe,” “expect,” “estimate,” “seek,” “predict,” “future,” “project,” “potential,” “continue,” “target” and similar words or expressions, or the negative thereof, are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. Any forward-looking statements in this press release are based on management's current expectations and beliefs and are subject to a number of risks, uncertainties and important factors that may cause actual events or results to differ materially from those expressed or implied by any forward-looking statements contained in this press release, including, without limitation, risks associated with: the impact of global economic uncertainty, geopolitical instability and conflicts, or public health epidemics or outbreaks of an infectious disease on countries or regions in which Relay Therapeutics has operations or does business, as well as on the timing and anticipated results of its clinical trials, strategy, future operations and profitability; significant political, trade or regulatory developments, such as tariffs, beyond Relay Therapeutics’ control; the delay or pause of any current or planned clinical trials or the development of Relay Therapeutics’ drug candidates; the risk that the preliminary or interim results of its preclinical or clinical trials may not be predictive of future or final results in connection with future clinical trials of its product candidates and that interim and early clinical data may change as more patient data become available and are subject to audit and verification procedures; Relay Therapeutics’ ability to successfully demonstrate the safety and efficacy of its drug candidates; the timing and outcome of its planned interactions with regulatory authorities; and obtaining, maintaining and protecting its intellectual property. These and other risks and uncertainties are described in greater detail in the section entitled “Risk Factors” in Relay Therapeutics’ most recent Annual Report on Form 10-K and Quarterly Report on Form 10-Q, as well as any subsequent filings with the Securities and Exchange Commission. In addition, any forward-looking statements represent Relay Therapeutics' views only as of today and should not be relied upon as representing its views as of any subsequent date. Relay Therapeutics explicitly disclaims any obligation to update any forward-looking statements. No representations or warranties (expressed or implied) are made about the accuracy of any such forward-looking statements. Contact: Mitch Maisel mmaisel@relaytx.com Media: Katie Engleman 1AB 919-333-7722 katie@1abmedia.com Relay Therapeutics, Inc. Condensed Consolidated Statements of Operations and Comprehensive Loss (In thousands, except share and per share data) (Unaudited) Three Months Ended June 30, Six Months Ended June 30, 2026 2025 2026 2025 Revenue: License and other revenue $ 350 $ 677 $ 3,350 $ 8,355 Total revenue 350 677 3,350 8,355 Operating expenses: Research and development expenses $ 76,483 $ 63,897 $ 147,046 $ 137,706 General and administrative expenses 14,691 13,627 25,718 32,366 Total operating expenses 91,174 77,524 172,764 170,072 Loss from operations (90,824 ) (76,847 ) (169,414 ) (161,717 ) Other income: Interest income 7,115 7,105 12,467 14,918 Other expense 2 (633 ) (51 ) (641 ) Total other income, net 7,117 6,472 12,416 14,277 Net loss $ (83,707 ) $ (70,375 ) $ (156,998 ) $ (147,440 ) Net loss per share, basic and diluted $ (0.41 ) $ (0.41 ) $ (0.82 ) $ (0.87 ) Weighted average shares of common stock, basic and diluted 202,849,466 171,264,622 191,412,839 170,254,500 Other comprehensive (loss) income: Unrealized holding (loss) gain (1,381 ) (201 ) (2,286 ) 828 Total other comprehensive (loss) income (1,381 ) (201 ) (2,286 ) 828 Total comprehensive loss $ (85,088 ) $ (70,576 ) $ (159,284 ) $ (146,612 ) Relay Therapeutics, Inc. Selected Condensed Consolidated Balance Sheet Data (In thousands) (Unaudited) June 30, 2026 December 31, 2025 Cash, cash equivalents and investments $ 910,934 $ 554,518 Working capital (1) 877,278 552,701 Total assets 967,457 621,331 Total liabilities 77,448 54,271 Total stockholders’ equity 890,009 567,060 Restricted cash 1,336 1,336 (1) Working capital is defined as current assets less current liabilities.

Phase 3Financial StatementClinical ResultLicense out/inPhase 1

02 Jun 2026

·www.biospace.com

ASCO: Pfizer scores in lung, colorectal and prostate cancer but key readouts still to come

iStock, Marut Khobtakhob Pfizer showcased multiple late-breakers at the American Society of Clinical Oncology’s annual conference but its biggest data are expected later this year. Pfizer arrived in Chicago this weekend for the American Society of Clinical Oncology’s annual conference fresh off a $10.5 billion deal with China’s Innovent Biologics, as the company seeks to bolster its oncology pipeline. “It is not a big [ASCO] year from the vantage-point of stock-moving data,” Leerink Partners analyst David Risinger told BioSpace . “The focus is looking forward to the Pfizer readouts ahead.” Risinger noted that the company’s most anticipated updates from an investor standpoint are set for later this year. The New York pharma giant showcased data across more than 40 abstracts at ASCO 2026, plus three late-breakers and several oral presentations. All told, the data ranged from striking, long-term results for approved drugs to previews of what’s coming, including some assets out of China. “We want to go big and make impact,” Johanna Bendell, Pfizer’s chief development officer of oncology, told BioSpace prior to the conference. China Pfizer bets up to $10.5B in 12-candidate cancer collab with China’s Innovent Pfizer continues its dealmaking spree by striking a back-heavy partnership with China’s Innovent Biologics to assemble a pipeline of antibody-based therapies for cancer. May 29, 2026 · 2 min read · Tristan Manalac Read more Wins in lung, colorectal and prostate cancer In its late-breaking abstracts, Pfizer presented new data for drugs already in clinic, cementing them as strong treatment options or providing evidence for their use in earlier-stage disease. The company on Friday shared updated data from its Phase 3 CROWN trial , comparing ALK inhibitor Lobrena to its earlier-generation oral kinase inhibitor Xalkori in patients with previously untreated, ALK-positive advanced non-small cell lung cancer (NSCLC). At seven years, patients taking Lobrena saw an 81% drop in the risk of disease progression or death. These patients had a 55% likelihood of being alive without disease progression, compared to just 3% of those in the control arm. Overall survival (OS) data is not yet available, Bendell said. Pfizer is hoping to see this metric within the next year. “The durability of the benefit is unlike any trial we’ve seen,” Sarah Goldberg, chief of thoracic oncology at Yale Cancer Center, told BioSpace . “The CROWN data have looked good for a long time, but as we get longer-term follow-up, I think it’s more convincing that this should be our choice for first-line treatment.” Meanwhile, Bendell, who previously treated patients with gastrointestinal cancers, is particularly excited about new results from BREAKWATER . The trial evaluates Pfizer’s BRAF inhibitor Braftovi plus Eli Lilly’s Erbitux and the FOLFIRI chemotherapy regimen for previously untreated patients with BRAF V600E-mutant metastatic colorectal cancer, compared to FOLFIRI with or without bevacizumab. FOLFIRI and FOLFOX are common chemo regimens for patients with colorectal cancer, and earlier BREAKWATER data showed strong benefit for Braftovi plus Erbitux and mFOLFOX6. The FDA granted Braftovi full approval in first-line metastatic colorectal cancer in February. In this latest readout from BREAKWATER, the Braftovi/FOLFIRI combo also cut the risk of progression or death, this time by 56%, and PFS nearly doubled to 15.2 months versus 8.3 months in the comparator arm. Risk of death also declined by 44%, according to Pfizer’s Monday press release . “You can choose whichever of the chemotherapy backbones. You’re still going to have a significant impact by bringing Braftovi in for these patients,” Bendell said. Meanwhile, adding Pfizer’s PARP inhibitor Talzenna to the company’s Xtandi resulted in better outcomes for men with HHR-altered metastatic castration-sensitive prostate cancer, according to results from the Phase 3 TALAPRO-3 trial . The combination resulted in a 52% reduction in risk of radiographic progression or death, compared to placebo plus Xtandi. At three years, some 77% of patients on the combination still had radiographic PFS (rPFS), compared to 56% of those in the control arm. The results from TALAPRO-3 could move the combination earlier into the disease course, before castration resistance, Bendell said. “The earlier you move the therapy, the more impact that you can have for patients.” The results could help support the growth of Talzenna going forward, as Xtandi is soon set to face generic competition, Risinger said, adding that those were very important results. A look ahead—and a patent cliff Elsewhere at ASCO, Pfizer unveiled new data from assets designed to be the future of its oncology business. One such drug is the company’s CDK4 inhibitor atirmociclib, the heir apparent to its blockbuster breast cancer drug Ibrance, which loses patent protection next year. Breast cancer Pfizer’s Ibrance Heir Reduces Risk of Death in Phase 2 Breast Cancer Test Pfizer has a lofty goal for the CDK4 inhibitor atirmociclib, the New York pharma’s answer to Ibrance’s loss of patent protection next year. In 2025, Ibrance led Pfizer’s oncology portfolio with $1.04 billion in sales. March 17, 2026 · 1 min read · Annalee Armstrong Read more The Phase 2 FourLight-2 trial evaluated neoadjuvant atirmociclib plus letrozole vs. letrozole alone among 121 patients with HR+/HER2- breast cancer. Based on Ki-67 biomarker data, the proportion of patients taking atirmociclib who achieved complete cell cycle arrest at two weeks was 88.2% compared to 17.9% in the comparator group. Patients on atirmociclib also had more side effects, with nearly 20% experiencing diarrhea. The efficacy was compelling, but the gastrointestinal toxicity is a key question going forward, Risinger said . Pfizer also put up data in the competitive PD-1/VEGF bispecific antibody space, where Summit Therapeutics and its Chinese biopharma partner Akeso made headlines with their candidate ivonescimab. BioNTech and Bristol Myers Squibb also presented solid data for their asset pumitamig. Immuno-oncology ASCO: Summit reached with China lung data but new climb begins to prove global benefit “King Keytruda’s reign continues,” analysts at BMO Capital Markets declared after Chinese data for Summit Therapeutics’ ivonescimab were revealed at the American Society for Clinical Oncology in Chicago. June 1, 2026 · 3 min read · Annalee Armstrong Read more In updated results from a Phase 2 trial of Pfizer’s bispecific PD-1/VEGF antibody SSGJ-707 (PF’4404), the confirmed objective response rate was 75.0% for patients with squamous-cell NSCLC and 63.6% for non-squamous cell NSCLC, with a median PFS of 8.9 months and 12.4 months, respectively. “The data were encouraging, but the jury is still out with respect to which agents will differentiate,” Risinger said. The compound also showed promise in endometrial cancer in a different Phase 2 trial . Among 29 patients with advanced or recurrent endometrial cancer, the confirmed objective response rate was 85.7% at a 5-mg/kg dose and 80.0% at 10 mg/kg. Pfizer paid $1.25 billion upfront to license the bispecific from 3SBio in 2025, and the company has since launched 12 clinical trials in the program and plans to start five more. As for key upcoming data, Risinger pointed to several readouts, including one around the middle of this year for Pfizer’s investigational antibody-drug conjugate (ADC) sigvotatug vedotin (SV) versus docetaxel in second-line NSCLC. Last week, Pfizer amended the primary endpoint to OS only, with the change likely to mildly increase the chance of success, analysts at BMO Capital Markets wrote in a note to investors last Wednesday. PFS will now be a descriptive secondary endpoint, the firm noted. “While such a change reduces our confidence in the robustness of PFS, OS remains the highest importance in NSCLC, making this change rationale for increasing SV’s chances to demonstrate clinically meaningful results,” the analysts wrote. “SV is expected to be a blockbuster for NSCLC,” Risinger said. Also awaited in the second half of 2026 are results from the Phase 3 MEVPRO-1 trial , evaluating the EZH2 inhibitor mevrometostat plus enzalutamide in patients with previously treated metastatic castration-resistant prostate cancer. Plus, this upcoming weekend, Phase 2 data will be presented for Pfizer’s monthly, long-acting injectable GLP-1 that it acquired from Metsera at the 2026 American Diabetes Association ’s Scientific Sessions, as the company builds out its obesity assets. As Risinger said, “there’s a broad pipeline at Pfizer that is needed to offset the patent cliffs ahead.” .responsive-container { display: flex; flex-wrap: wrap; border: 1px solid #ededed; font-family: Helvetica, Arial, Sans-Serif; padding: 20px 20px 10px 20px; } .column-left { flex: 1; max-width: 45%; padding: 20px 20px 10px 20px; } .column-right { flex: 2; padding: 20px 20px 10px 20px; } @media (max-width: 768px) { .column-left, .column-right { max-width: 100%; flex: 100%; padding: 10px 0; } } Subscribe to ClinicaSpace! Clinical trial results, research news, the latest in cancer, cell and gene therapy hbspt.forms.create({ region: "na1", portalId: "4413123", formId: "674f4dc0-7371-4190-86cc-e1afd00b08ea", onFormSubmitted: function($form, data) { window.dataLayer = window.dataLayer || []; window.dataLayer.push({ 'event': 'GTMevent', 'event_name': 'newsletter_sign_up' }); } });

Clinical ResultPhase 3Phase 2Drug ApprovalASCO

22 May 2026

·endpoints.news

Ibrance's would-be successors, the data that helped sell Tubulis to Gilead, and more at ASCO

All of the regular ASCO abstracts dropped Thursday afternoon, with the biggest news coming from the VEGF bispecific race , Merck and Kelun-Biotech’s TROP2 ADC known as sac-TMT, and multiple head and neck cancer updates . But there were plenty of other developments across cancer trials and new mechanisms, and we’ve rounded up the best of the rest here. Find updates below on potential successors for Pfizer’s blockbuster Ibrance, the Tubulis data that got Gilead Sciences excited enough to buy it out, and more. Both Pfizer and BeOne Medicines (formerly BeiGene) are developing CDK4 inhibitors in a bid to take up Ibrance’s mantle in breast cancer, as the first Ibrance biosimilars are expected as soon as next year. For Pfizer, the successor is called atirmociclib. The drugmaker toplined a separate Phase 2 success earlier this year in HR-positive, HER2-negative breast cancer, but an abstract released Thursday supplemented those results. Patients received either a combination of atirmociclib and an aromatase inhibitor called letrozole, or letrozole alone. Efficacy was measured with an endpoint called “complete cell cycle arrest,” or CCCA, which examines how quickly patients’ tumor cells stopped dividing. After 14 days, 45 of 51 patients (88.2%) who took the combination regimen saw their cell division slow by a meaningful amount, compared to 10 of 56 (17.9%) who only received letrozole. The data come from patients with advanced breast cancer who progressed after treatment with a CDK4/6 inhibitor (including Ibrance). Pfizer enrolled patients whose tumor cells were dividing rapidly. BeOne, meanwhile, is researching a program called BGB-43395 and reported data from a safety expansion cohort of a Phase 2 study, also looking at a combination with letrozole. The company has enrolled 58 patients so far across three dosing regimens. After a median follow-up of 6.8 months, the median time-to-response was 3.6 months and progression-free survival was not reached. Unlike these experimental drugs, Ibrance is a CDK4/6 inhibitor. Global Ibrance sales peaked in 2022 with $5.12 billion. In 2025, Ibrance was selected for the second round of price negotiations under the Inflation Reduction Act, with new prices expected to be implemented for patients with Medicare starting next year. Gilead paid $3.15 billion upfront last month to acquire the ADC-focused biotech Tubulis, and an ASCO abstract released Thursday attempts to show why. The biotech’s lead program is called TUB-040, a NaPi2b-directed ADC that is in testing for certain forms of ovarian cancer and non-small cell lung cancer. Tubulis administered the drug to patients with platinum-resistant ovarian cancer across four dose levels in a Phase 1/2a study, 46 of whom could be evaluated for efficacy. Of those 46 patients, 28 saw their tumors shrink by at least 30%, good for a confirmed objective response rate of 60.9%. Responses were spread almost evenly across all dose levels, with seven patients responding in each of the two lowest doses, eight responding in the third level and six responding at the highest dose. Gilead and Tubulis initially signed a partnership in 2024 before this year’s buyout. Gilead could pay another $1.85 billion if all milestones in the deal are met. Earlier this month, the FDA approved Pfizer and Arvinas’ drug vepdegestrant (brand name: Veppanu) for patients with a certain form of breast cancer. But it’s unclear how many patients will take it, and the companies shipped the drug’s rights to Rigel Pharmaceuticals for $70 million upfront — a fraction of the $1 billion Pfizer initially paid for the partnership. Data released Thursday from a Phase 1b/2 study continued to illustrate why the drug has disappointed. In second-line patients with certain ER-positive/HER2-negative breast cancers, Veppanu plus an aromatase inhibitor induced responses in just eight of 33 patients at the highest dose measured (24.2% confirmed ORR). Only five of 31 who received the low dose responded to the therapy. Response rates were lower in patients with ESR1 mutations, with three of 14 patients (21.4%) responding to the high dose. These mutations are where the expected competition of oral SERDs has largely been a success. Pfizer and Arvinas presented Phase 3 data for the drug at last year’s ASCO, showing it was no better than oral SERDs. AstraZeneca’s B7-H4 ADC: The drug is called puxitatug samrotecan, or puxi-sam. At its low dose, 14 of 31 patients with endometrial cancer (34.1% ORR) and four of 33 with ovarian cancer (12.1% ORR) saw their tumors shrink by at least 30%. At the high dose, 24 of 50 endometrial cancer patients (48% ORR) and 11 of 45 individuals with ovarian cancer (24.4% ORR) saw the same level of tumor shrinkage. Median PFS in endometrial cancer was 8.1 months and seven months at the high and low doses, respectively. In ovarian cancer, median PFS was 5.7 months at the high dose and 4.8 months at the low dose. Additionally, the company released very early data from a cohort looking at patients with biliary tract cancer. After a median follow-up of 2.2 months, two of 20 patients saw their tumors shrink by at least 30%, good for an ORR of 10%. The company hopes more patients will respond after longer periods of time. Immuneering posts more pancreatic cancer results: The biotech rolled out another update for its oral MEK inhibitor atebimetinib, after multiple positive updates in the last 12 months measuring it in combination with chemotherapy. After a median follow-up of 10.4 months, median PFS was 8.4 months and median overall survival was not reached among 50 patients. Six- and nine-month OS rates were 88% and 79%, respectively. AstraZeneca’s Neogene data: The first data from AstraZeneca’s 2022 buyout of Neogene were released Thursday, showing results from the NT-175 program in patients with TP53 mutations in solid tumors. Investigators said 10 of 21 patients who received the therapy responded after a median six months of follow-up. This included five of six patients with pancreatic cancer who took part in the study. NT-175 is an autologous engineered T-cell receptor (eTCR) T cell therapy. Replimune’s three-year survival rates: The company’s therapy RP1, which was rejected twice by the FDA , achieved a three-year OS rate of 45.5% in patients with advanced melanoma. Patients got RP1 along with the anti-PD-1 drug Opdivo after previously failing anti-PD-1 therapy.

Clinical ResultPhase 3Drug ApprovalPhase 2Cell Therapy

100 Deals associated with Atirmociclib

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Indication	Highest Phase	Country/Location	Organization	Date
Hormone receptor positive HER2 negative breast cancer	Phase 3	United States	Pfizer Inc.	06 Jan 2025
Hormone receptor positive HER2 negative breast cancer	Phase 3	China	Pfizer Inc.	06 Jan 2025
Hormone receptor positive HER2 negative breast cancer	Phase 3	Japan	Pfizer Inc.	06 Jan 2025
Hormone receptor positive HER2 negative breast cancer	Phase 3	Argentina	Pfizer Inc.	06 Jan 2025
Hormone receptor positive HER2 negative breast cancer	Phase 3	Australia	Pfizer Inc.	06 Jan 2025
Hormone receptor positive HER2 negative breast cancer	Phase 3	Belgium	Pfizer Inc.	06 Jan 2025
Hormone receptor positive HER2 negative breast cancer	Phase 3	Brazil	Pfizer Inc.	06 Jan 2025
Hormone receptor positive HER2 negative breast cancer	Phase 3	Bulgaria	Pfizer Inc.	06 Jan 2025
Hormone receptor positive HER2 negative breast cancer	Phase 3	Canada	Pfizer Inc.	06 Jan 2025
Hormone receptor positive HER2 negative breast cancer	Phase 3	Chile	Pfizer Inc.	06 Jan 2025

Clinical Result

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Study	Phase	Population	Analyzed Enrollment	Group	Results	Evaluation	Publication Date


NCT06465368 (FourLight-2, CTgov)	Phase 2	Hormone receptor positive HER2 negative breast cancer	121	PF-07220060+Letrozole (PF-07220060 + Letrozole)	qnbfpvcllu = xewztruaol qmjmlmuwoz (babiahdeqm, aniacwnelj - nqoctrjjdx) View more	-	15 Jul 2026
				Letrozole (Letrozole Alone)	qnbfpvcllu = qkssgfcavx qmjmlmuwoz (babiahdeqm, qawdrejrgr - zjggtewnph) View more
NCT06465368 (FourLight-2, ASCO2026)	Phase 2	Hormone receptor positive HER2 negative breast cancer Neoadjuvant HR+ \| HER2−	121	Atirmociclib +Letrozole	xsucvscuqs(oyrbigofcg) = opbbwtcvko taoknncozi (qmxuihfmme, 76.6 - 94.5) View more	Positive	29 May 2026
				Letrozole	xsucvscuqs(oyrbigofcg) = oaeboqqack taoknncozi (qmxuihfmme, 10.0 - 29.8) View more
NCT06105632 (FOURLIGHT-1, Company_Website) Manual	Phase 2	Hormone receptor positive HER2 negative breast cancer Second line HER2 Negative \| HR Positive	264	Atirmociclib + Fulvestrant	jshfnnesnq(eyickcwnyp): HR = 0.6 (95.0% CI, 0.44 - 0.825), P-Value = 0.0007 Met View more	Positive	17 Mar 2026
				fulvestrant+exemestane or everolimus + exemestane
NCT06267963 (CTgov)	Phase 1	-	12	PF-07220060 (Cohort 1: 14C PF-07220060 100 mg Oral)	dwmkqgsuad(zyruuoiiru) = dbsyyyremy zcimdeqskh (ilxdlphuwy, 3.0) View more	-	10 Mar 2026
				PF-07220060 (Cohort 2: PF-07220060 100 mg Oral + 14C PF-07220060 100 mcg IV)	dwmkqgsuad(zyruuoiiru) = jzrzyyoqeq zcimdeqskh (ilxdlphuwy, 3.0) View more
NCT06465368 (ESMO2025)	Phase 2	Early Stage Breast Carcinoma First line HR+/HER2−	118	AtirmociclibLetrozolelib + AtirmociclibLetrozole	tbthheiapd(mrhhqkfeqi) = Atirmociclib plus letrozole had a higher incidence of any-grade pneumonitis (10.3% vs 0.9%) and any-grade rash maculo-papular (16.9% vs 0%). pqxpbbvuum (pxslurgfio )	Positive	17 Oct 2025
				Letrozole
NCT06760637 (ESMO2025)	Phase 3	Advanced breast cancer First line HR+/HER2−	1,020	Atirmociclib plus letrozole	pfrlzgsthq(pzolgcsere) = ogezdtcgno qybkluqzpa (epoiojqdmx, 36.0 - NR) View more	Positive	17 Oct 2025
				CDK4/6 inhibitor plus letrozole	swhzqewvfn(xynfjarkmy) = fohnxblenk iuakwnibep (muwuoppqxg, NR - 37+) View more
NCT04557449 (ESMO2025)	Phase 1	Metastatic breast cancer First line HR+ \| HER2-	34	Atirmociclib + letrozole (HR+/HER2− metastatic breast cancer)	xzdgkcogpe(vkchtmugvk) = AEs led to a single dose reduction in 6 pts (17.6%): 2 in cycles 3−6, 1 in cycles 7−12, 2 in cycles 13−24 and 1 in cycles ≥25 jlefpsvdng (auggjjpoca ) View more	Positive	17 Oct 2025
NCT04557449 (Phase I study, ESMO_BC2025)	Phase 1/2	Hormone receptor positive HER2 negative breast cancer Thymidine kinase	58	Atirmociclib 300 mg BID + Letrozole	imcnsvnfzb(xpufylkrlf) = dxtztvzfkb sameldsgva (aayiebomzq )	Positive	14 May 2025
				Atirmociclib 400 mg BID + Letrozole	imcnsvnfzb(xpufylkrlf) = jvibahcsku sameldsgva (aayiebomzq )
NCT04557449 (phase I/IIa study, ESMO2024)	Phase 1/2	Metastatic breast cancer ESR1 \| PIK3CA \| TP53	33	PF-07220060 + Fulvestrant	vjpnadkhvy(ztrmvfcmqo) = kibsfcojow kwshwhcrhb (jymbktqgrw )	Positive	16 Sep 2024
				PF-07220060 + Letrozole	vjpnadkhvy(ztrmvfcmqo) = lpvwikmkug kwshwhcrhb (jymbktqgrw )
NCT05262400 (ESMO2024) Manual	Phase 1/2	Advanced Malignant Solid Neoplasm \| Hormone receptor positive HER2 negative breast cancer HR Positive \| HER2 Negative \| ESR1 Mutation	33	PF-07220060 PF-07104091tive inhibitor)	cwzgiqggls(lhaytjgltz) = faudouufib nbuxqcdyxy (fzncatxfog ) View more	Positive	14 Sep 2024

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