KymaThera raises $80 million in Series B financing to advance K-1728, an investigational PI3Kα inhibitor targeting mutant cancers and vascular malformations.
Written By: Siddhi Bhadekar, M. Pharm (QA)
Reviewed By: Pharmacally Editorial Team
KymaThera, a San Diego-based biotechnology company developing precision medicines, has closed an $80 million Series B financing to advance its lead investigational candidate, K-1728, toward clinical development. The financing, announced on October 6, 2026, was led by Alta Partners, with participation from existing investors Venrock and Foresite Capital and new investor J. Wood Capital.
K-1728 is an investigational oral, pan-mutant selective PI3Kα inhibitor designed to inhibit disease-driving mutations in both the kinase and helical domains of PI3Kα while sparing wild-type PI3Kα. KymaThera is initially developing the candidate in HR+/HER2- breast cancer and PI3Kα-driven vascular malformations.
Series B Financing to Support K-1728 Development
The Series B follows KymaThera’s 2024 Series A financing, which was co-led by Foresite Capital and Venrock. With the latest financing, the company said its total funding now exceeds $100 million.
Most of the new capital will be directed toward K-1728, supporting its advancement from preclinical development into clinical testing.
Investor comments accompanying the financing focused on KymaThera’s drug-discovery capabilities and the potential of K-1728. Bob More, Partner at Alta Partners, highlighted the management team’s experience in drug discovery. Michael Rome, Ph.D., of Foresite Capital described K-1728 as an internally discovered and wholly owned molecule, while Mariana Mihalusova, Ph.D., of Venrock highlighted the progress made by the company over the previous two years.
K-1728 Designed for Mutant-Selective PI3Kα Inhibition
K-1728 is an oral PI3Kα inhibitor designed to selectively inhibit disease-driving mutations in both the kinase and helical domains of PI3Kα while sparing wild-type PI3Kα.
According to KymaThera, the molecule was discovered internally using structure-based drug discovery. The company is developing K-1728 to address limitations associated with earlier PI3Kα inhibitors, particularly toxicity associated with inhibition of wild-type PI3Kα and incomplete coverage of clinically relevant PI3Kα mutations.
KymaThera Chief Executive Officer Rob Kania, Ph.D., described K-1728 as having high potency and a broad selectivity window for helical-domain mutants. These differentiation claims are based on company-reported findings and have not yet been independently validated in clinical studies.
Preclinical Findings Support Clinical Development
KymaThera said preclinical and IND-enabling studies demonstrated potent activity against PI3Kα mutations in both the kinase and helical domains. The company also reported tumor regressions at low, once-daily doses in multiple PI3Kα-mutant models.
According to the company, the studies also demonstrated a broad preclinical therapeutic window, defined by a separation between exposures associated with deep tumor regression and those associated with hyperglycemia.
However, the financing announcement does not provide detailed numerical efficacy results, specific model identities, or a peer-reviewed publication describing the findings. As a result, the magnitude and reproducibility of the reported preclinical effects cannot yet be independently assessed from the information disclosed.
These findings provide the preclinical rationale for advancing K-1728 into human testing, but they do not establish safety or efficacy in patients.
Initial Development Areas
KymaThera is initially developing K-1728 in hormone receptor-positive, HER2-negative (HR+/HER2-) breast cancer and PI3Kα-driven vascular malformations.
In HR+/HER2- breast cancer, the company plans to evaluate K-1728 as both monotherapy and in combination treatment regimens. KymaThera cites continuing unmet need in this patient population despite available therapies.
For PI3Kα-driven vascular malformations, the company plans to evaluate K-1728 as monotherapy. KymaThera describes these conditions as serious and potentially debilitating disorders for which systemic treatment options remain limited.
Beyond these initial development areas, the company plans to investigate K-1728 across a broader range of PI3Kα-mutant cancers and vascular malformations.
KymaThera also said it is advancing earlier-stage discovery programs against additional validated disease targets, although it did not disclose details of those programs.
Phase 1 Development Expected in Q4 2026
K-1728 remains an investigational compound, and the financing announcement does not report human safety, pharmacokinetic, or efficacy data.
KymaThera expects first patient dosing in a Phase 1 clinical study in the fourth quarter of 2026. The announcement does not disclose the planned Phase 1 dose levels, enrollment size, study design, or timing for initial clinical proof-of-concept data.
The Phase 1 study will represent the first clinical evaluation of K-1728 and will be important for determining its safety, tolerability, pharmacokinetic profile, and preliminary clinical activity.
At this stage, however, the therapeutic potential of K-1728 remains investigational. The company’s reported preclinical selectivity and antitumor activity will need to be evaluated in clinical studies before conclusions can be drawn about its safety, efficacy, or potential advantages over existing PI3Kα-directed therapies.
Reference
KymaThera Announces $80 Million Series B Financing to Advance K-1728, a Next-Generation Pan-Mutant Selective PI3Kα Inhibitor, for Cancer and Vascular Malformations, KymaThera via prnewswire, 06 October 2026
About the Writer
Siddhi Rajendra Bhadekar (Linkedin) is an M.Pharm professional with expertise in medical and scientific writing, literature review, publication writing, and evidence synthesis, supported by four peer-reviewed publications.
She brings working knowledge of ICH-GCP, MedDRA, pharmacovigilance, ADR/AE reporting, clinical data management, and regulatory documentation.
With experience across pharmaceutical R&D, Quality Control, and Quality Assurance, she combines scientific research skills with strong attention to accuracy and detail.
Her background in manuscript development, publication planning, and scientific communication enables her to translate complex healthcare information into clear, reliable content.