Kairos Pharma announces Bayer collaboration to test ENV-105 with XOFIGO

Kairos Pharma, Ltd. (NYSE American: KAPA) announced a strategic collaboration with Bayer to evaluate its lead antibody, ENV-105 (carotuximab), in combination with Bayer's XOFIGO (radium-223 dichloride) in metastatic castration-resistant prostate cancer (mCRPC) involving bone. The announcement was made in a press release dated July 22, 2026, filed as Exhibit 99.1 to a Form 8-K. The release describes ENV-105 as a first-in-class CD105/BMP signaling inhibitor. It does not state the start date, the size or the financial terms of the collaboration.

The rationale

Kairos says CD105 is upregulated in response to standard androgen receptor inhibition and in response to ionizing radiation, where it drives pro-survival BMP-SMAD signaling pathways underlying therapy resistance. The company states that previously published work demonstrated the efficacy of ENV-105 in radiation sensitization in prostate cancer preclinical models. In its view, targeting CD105 with ENV-105 re-sensitizes resistant tumors and may extend the duration and depth of response to XOFIGO's targeted alpha therapy.

Chief Executive Officer John Yu, M.D., said: "Drug resistance remains one of the greatest challenges in advanced prostate cancer, and XOFIGO, like many standard-of-care therapies, can lose efficacy over time." Neil Bhowmick, Ph.D., Chief Scientific Officer and Principal Investigator, said that "CD105's role as a central resistance mechanism validated now across multiple drug classes makes this collaboration scientifically compelling and clinically timely, given XOFIGO's recent Phase III momentum."

XOFIGO and the company's data

The release describes XOFIGO as the first and only FDA-approved alpha-emitting radiopharmaceutical for mCRPC with symptomatic bone metastases. It says XOFIGO is advancing through additional combination studies, including the Phase III PEACE-3 trial, which demonstrated a 24% reduction in mortality risk when combined with enzalutamide (HR 0.76; p=0.009).

Kairos points to its own clinical work as well. The release says that last year the company announced positive interim efficacy data from its Phase 2 trial, showing median progression-free survival of more than 13 months, and that those data were presented at the 2025 ESMO Congress in Berlin. The release's headline cites an 86% clinical benefit rate for ENV-105 in resistant mCRPC. The company's current ENV-105 programs include a Phase 1 trial in EGFR-driven non-small cell lung cancer and a Phase 2 trial in castrate resistant prostate cancer.

Company background

In its annual report on Form 10-K, filed March 31, 2026, Kairos describes itself as a clinical-stage biopharmaceutical company developing antibodies and small molecules for prostate cancer, lung cancer, breast cancer and glioblastoma. Its proprietary technologies are licensed from Cedars-Sinai Medical Center. The company says ENV 105 targets endoglin, also known as CD105, and that the Enviro Therapeutics, Inc. acquisition, announced in June 2021, added the pipeline.

Financial position

SEC XBRL data show research and development expense of $2.1 million for 2025, compared with $414,000 for 2024. The net loss was $5.4 million for 2025 and $2.6 million for 2024, and cash flow from operations was negative $3.4 million in 2025 and negative $4.0 million in 2024. Year-end 2024 cash and cash equivalents were $1.3 million. The release does not state a cash runway.

What the release does not show

The release does not state the start date, size or financial terms of the collaboration, so it describes an intention, not a finished arrangement. The PEACE-3 result it cites is for XOFIGO plus enzalutamide, not for ENV-105. The 86% clinical benefit rate and the 13-month progression-free survival come from an ongoing Phase 2 trial, with no patient numbers, p-values or confidence intervals in the release. The 10-K, for its part, reports a clinical benefit rate of 62% in a Phase 2 trial of heavily pre-treated patients, and says ENV105 alone has shown no clinical benefit in preclinical and earlier clinical findings. The CEO's reference to a strong safety profile comes with no safety data.

Kairos has no approved product: its 10-K says none of its candidates has been approved as safe or effective by the FDA or any comparable foreign regulator. The 2025 net loss was $5.4 million and cash flow from operations was negative $3.4 million, and the release does not state a cash runway.

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