ASCO GU: ECLIPSE Substudy Dosimetry Supports up to 6 7.4 GBq Cycles

A press release reports the first pharmacokinetic and dosimetry readout from the ECLIPSE PK/dosimetry substudy (n=26) of Lu-177 zadavotide guraxetan, along with a sponsor-described protocol amendment to allow up to six cycles at 7.4 GBq per cycle (previously four).

The release says the findings were presented as an ASCO GU 2026 poster (Abstract #174) in San Francisco. The update is framed around a dosimetry-based rationale for expanding the protocol’s maximum number of planned cycles.

According to the release, the substudy was a nonrandomized pharmacokinetic/dosimetry component within the ongoing pivotal Phase 3 ECLIPSE clinical trial (NCT05204927). The press release describes ECLIPSE as evaluating lutetium-177 zadavotide guraxetan (described as a proprietary formulation of 177Lu-PSMA-I&T) in patients with metastatic castration-resistant prostate cancer who have progressed on prior androgen receptor pathway inhibitor therapy. For the substudy, the stated focus was biodistribution and estimation of radiation absorbed dose to “organs of interest,” positioning the work as measurement-focused rather than an outcomes comparison.

For the dosimetry readout, the press release characterizes organ radiation absorbed doses as “favorable” and notes that the poster discussion was intended to identify organs at highest risk of radiation exposure. The release does not enumerate organ-by-organ absorbed-dose values or specify which organs were highest in the text, instead emphasizing the availability of dosimetry data as the main quantitative output from this embedded substudy. In that framing, the stated takeaway is that organ-level absorbed-dose estimation was central to the substudy’s deliverable for ECLIPSE.

The sponsor’s stated rationale for the protocol change centers on renal projections, described in a quotation from Curium’s Chief Medical Officer. In the quoted statement, projected mean cumulative renal doses were described as remaining low for a six-cycle treatment regimen, and the sponsor linked that projection to an amendment increasing the maximum planned dosing from four to six cycles at 7.4 GBq per cycle. The release presents the renal-dose projection as the key basis offered for expanding the allowable number of cycles within the trial.

Key Takeaways:

• A GlobeNewswire press release reported first PK and dosimetry findings from a nonrandomized ECLIPSE substudy and noted presentation at ASCO GU 2026 (Abstract #174).
• The sponsor stated that projected mean cumulative renal doses were described as remaining low for a six-cycle regimen, and linked this projection to a protocol amendment allowing additional cycles.
• The release characterized organ absorbed doses as favorable and framed the substudy’s role as providing organ-level dosimetry information to inform protocol design within ECLIPSE.