AMBIGUOUS RESULTS

Radiopharm's RAD204 shows one durable partial response in dose-escalation cohort

A single Cohort 3 patient hit a RECIST-confirmed 43% tumor reduction on the PD-L1-targeted radiotherapeutic, an early Phase 1 dose-finding signal, not a powered efficacy result.

Radiopharm Theranostics disclosed that the first patient dosed in the third cohort of its RAD204 Phase 1 trial achieved a RECIST-confirmed partial response, with a second patient showing early tumor shrinkage and no dose-limiting toxicities reported across any cohort.

By AppliedXLJuly 22, 2026Trial NCT06305962

Executive Summary

Radiopharm Theranostics reported a confirmed partial response and a second patient with early tumor shrinkage from its Early Phase 1 dose-escalation trial of RAD204, a PD-L1-targeted radiopharmaceutical, alongside a favorable tolerability signal with no dose-limiting toxicities across cohorts.
The trial's registered primary endpoints are pharmacokinetics, radiation dosimetry, and safety rather than tumor response, so the antitumor signal is a secondary observation feeding dose selection rather than the metric the study is designed to prove.
The finding comes from two patients dosed at the current highest dose level, with a third still being screened, in a trial with an anticipated total enrollment of 30 patients across six tumor types.
RAD204 sits in a checkpoint-blockade field crowded with PD-L1-directed antibodies in Phase 2 and Phase 3 testing, but it is the only radiopharmaceutical nanobody targeting PD-L1 among the identified comparators, competing on mechanism rather than replicating an established antibody approach.
The company had guided to mid-2026 interim data across additional RAD204 and RAD202 cohorts, and this update landed in that window, extending rather than concluding the readout.

The disclosure

Radiopharm Theranostics (Radiopharm) announced updated results on July 22, 2026, from the third dosing cohort of its Phase 1 trial of RAD204, a lutetium-177-labeled anti-PD-L1 nanobody radiotherapeutic tested in patients with advanced tumors after progression on prior therapy. Two patients have been dosed at the 90 mCi level to date, with a third patient under screening. Patient 1 showed tumor shrinkage of 19% after the first dose, 43% after the second dose (meeting RECIST criteria for partial response), and maintained that 43% reduction through a third dose before declining slightly to 35% after a fourth, remaining progression-free beyond seven months. Patient 2 showed a 7% reduction after a first treatment cycle and remains on treatment. Radiopharm reported no dose-limiting toxicities across any of the three dosing cohorts tested so far. Radiopharm

Probability of Success

Endpoint Met65%

Completes82%

Clinical Significance12%

Regulatory69%

What the trial is built to measure

The study, registered as NCT06305962, is an Early Phase 1, single-arm, open-label trial enrolling an anticipated 30 patients with PD-L1-positive relapsed or refractory non-small cell lung cancer, small cell lung cancer, triple-negative breast cancer, cutaneous melanoma, head and neck squamous cell carcinoma, or endometrial cancer, run in Australia. Its six registered primary endpoints cover the biokinetics, pharmacokinetics, and radiation dosimetry of the imaging and therapeutic RAD204 constructs, the recommended dose or doses for further exploration, and safety and tolerability. Antitumor activity is listed only as a secondary endpoint. That structure means the partial response Radiopharm highlighted answers a question the trial is not primarily designed to test, even though the company's own framing centers the result around informing the recommended Phase 2 dose. NCT06305962+1

CEO framing

Riccardo Canevari, Radiopharm's CEO and Managing Director, called the finding evidence of "the broad therapeutic potential of RAD204 in PD-L1-associated malignancies" and said the totality of data across dose cohorts "support our confidence in this program" ahead of a planned Phase 2 trial. The trial's registry record classifies it as non-registrational, and the current evidence base behind that statement is two patients in the top dose cohort, one of whom achieved a confirmed response and one of whom is at an early stage of treatment. Radiopharm+1

Where it sits competitively

PD-L1 remains one of oncology's most tested targets: the checkpoint-blockade field includes Phase 3 programs from AstraZeneca's durvalumab in small cell lung cancer, Bristol-Myers Squibb's pumitamig and Suzhou Suncadia's SHR-8068 in non-small cell lung cancer, all monoclonal or bispecific antibodies rather than radiopharmaceuticals. Field activity for PD-L1 programs has declined, with roughly 193 recent trials against 1,260 in prior years, a signal of a maturing rather than expanding target class. Against that backdrop, RAD204's nanobody-radioisotope approach is a mechanistically distinct entrant rather than a challenger to the antibody-based standard: it aims to deliver localized radiation to PD-L1-expressing tumor tissue rather than block checkpoint signaling systemically, a hypothesis the trial's dosimetry-focused endpoints are built to test before any efficacy claim can be assessed at scale.

Operational context

The trial's enrollment target rose from 23 to 30 patients and its primary completion date moved from July 2025 to December 2027, both changes recorded in a single registry update in February 2026. The enrollment change sits within the routine band the operational model uses to flag increases, and is consistent with a trial still escalating through dose cohorts. The extended completion date reflects a Phase 1 trial still adding dose levels and patients rather than a program in distress. NCT06305962

This analysis was produced using AI-assisted reporting systems, AppliedXL data, and official public records. These systems undergo editorial review, quality checks, and regular audits by human experts. Errors may still occur, as with any automated system. Always consult the linked primary sources. Read our AI Editorial Policy.