Pfizer discontinues three investigational programmes in ITP, PAH and obesity, with trial records citing business decisions for two terminations.
Written By: Saniya Katakdhond, PharmD
Reviewed By: Pharmacally Editorial Team
Pfizer has discontinued three investigational drug programmes targeting primary immune thrombocytopenia (ITP), pulmonary arterial hypertension (PAH) and obesity, according to its November 3, 2026 pipeline update. The affected candidates are PF-06835375, an anti-CXCR5 biologic; PF-07868489, a biologic targeting bone morphogenetic protein 9 (BMP9); and PF-07999415, an investigational obesity biologic with an undisclosed mechanism of action.
The decisions involve different stages of clinical development and distinct circumstances. Clinical-trial records attribute the ITP and PAH trial terminations to business decisions, explicitly ruling out safety concerns in ITP and both safety and efficacy concerns in PAH. In contrast, Pfizer has not disclosed the reason for discontinuing PF-07999415, whose Phase 1 study had already been completed.
PF-06835375: Phase 2 ITP Programme Ends on Business Grounds
PF-06835375 was an investigational anti-CXCR5 biologic evaluated for primary ITP, an autoimmune disorder characterised by reduced platelet counts and an increased risk of bleeding.
Pfizer investigated the candidate in a Phase 2, open-label, multicentre study (NCT05070845) involving adults with moderate-to-severe primary ITP. The trial enrolled 61 participants and evaluated different dosing regimens, with changes in platelet counts serving as the primary efficacy assessment.
ClinicalTrials.gov records show that the study was terminated on October 13, 2026. The sponsor identified a business decision as the reason and explicitly stated that the termination was not based on safety concerns.
Secondary assessments included modified overall response, complete response, treatment-emergent adverse events and changes in circulating B-cell and T-follicular helper-cell populations.
Although Pfizer ruled out safety concerns as the reason for termination, the available disclosure does not establish whether efficacy considerations influenced the broader development decision. The termination therefore does not, by itself, demonstrate that CXCR5 inhibition was ineffective in ITP.
PF-07868489: Phase 2 PAH Development Ends Without Safety or Efficacy Concerns
PF-07868489 was an investigational biologic targeting bone morphogenetic protein 9 (BMP9), developed for PAH. The candidate had reached Phase 2 and received US Orphan Drug designation.
BMP9 is involved in signalling pathways associated with pulmonary vascular biology. PF-07868489 represented an investigational approach targeting this pathway in pulmonary vascular disease.
Pfizer’s open-label Phase 2 extension study (NCT07073820) evaluated the long-term safety, tolerability and treatment effects of PF-07868489 in adults with PAH who had previously participated in a clinical study of the candidate. The extension enrolled 42 participants.
The clinical-trial registry recorded the study’s termination on November 2, 2026. Pfizer attributed the decision to a business consideration and explicitly stated that it was unrelated to safety or efficacy concerns.
This disclosure provides a clearer explanation than the ITP trial record. However, it does not establish that the candidate demonstrated clinical benefit or that BMP9-targeted approaches will necessarily succeed in future PAH research.
PF-07999415: Obesity Programme Discontinued After Phase 1 Completion
PF-07999415 was an investigational biologic being developed for obesity. Pfizer listed the candidate in Phase 1 development, but its pipeline disclosure did not identify its molecular target or mechanism of action.
The associated Phase 1 study (NCT06965465) evaluated safety, tolerability and pharmacokinetics following single ascending subcutaneous doses in healthy adult participants. The study enrolled 32 participants and reached primary completion in August 2026. Clinical-trial records list the study as completed, rather than terminated.
Unlike the ITP and PAH programmes, Pfizer has not disclosed a specific reason for discontinuing PF-07999415.
The distinction between trial completion and programme discontinuation is particularly relevant here. Completion of the Phase 1 study does not establish that the candidate demonstrated sufficient potential to advance, while its subsequent removal from the pipeline does not establish clinical failure. The available information does not disclose whether study findings, commercial considerations or broader portfolio priorities influenced the decision.
Discontinuations Reflect Different Development Decisions, Not Established Clinical Failures
The three discontinuations illustrate why pipeline changes need to be interpreted alongside sponsor disclosures and clinical-trial records.
For PF-06835375, Pfizer identified a business decision but ruled out safety concerns. For PF-07868489, the company explicitly ruled out both safety and efficacy concerns as reasons for terminating the PAH extension. For PF-07999415, the reason remains undisclosed despite completion of its Phase 1 study.
These distinctions do not establish the therapeutic potential of the candidates or their underlying biological targets. Without publicly disclosed efficacy findings, the clinical performance of the discontinued programmes cannot be independently determined.
Pfizer’s November update therefore reflects changes in selected development priorities rather than evidence of failure across all three therapeutic approaches.
Pfizer Continues to Advance Its Obesity Research
Despite discontinuing PF-07999415, Pfizer continues to advance its broader obesity research portfolio. Its pipeline includes berobenatide (PF-08653944), a GLP-1 receptor agonist listed in Phase 3 development for chronic weight management, alongside combination approaches involving GLP-1 and amylin pathways.
The development changes therefore do not indicate a broader withdrawal from metabolic medicine. Further disclosures from Pfizer and the publication of clinical-trial findings will be important for understanding the decisions behind these discontinued programmes and the evidence generated during their development.
Reference
Pfizer Pipeline, 03 November 2026
Safety and Efficacy Study of PF-06835375 in Primary Immune Thrombocytopenia, ClinicalTrials.gov ID NCT05070845
A Study to Learn About the Study Medicine (Called PF-07868489) in People With Pulmonary Arterial Hypertension Who Have Previously Participated in a Clinical Study With PF-07868489, ClinicalTrials.gov ID NCT07073820
A Study to Learn How Different Amounts of the Study Medicine Called PF-07999415 Are Tolerated and Act in the Body in Healthy Adults, ClinicalTrials.gov ID NCT06965465
About the Writer
Saniya Sanjay Katakdhond (Linkedin) is a Doctor of Pharmacy professional with hands-on experience in patient case review, clinical documentation, medical record analysis, and patient care.
Her hospital experience has strengthened her understanding of clinical conditions, treatment approaches, and multidisciplinary healthcare practices.
With ICH-GCP certification and a research-oriented approach, she brings clinical insight and attention to detail to healthcare content development.
As a healthcare writer, Saniya focuses on translating clinical knowledge and patient-care experience into clear, accurate, and evidence-informed medical content.