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The 2026 ASTRO Multidisciplinary Radiopharmaceutical Therapy Symposium
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| Hematologic Toxicity Outcomes of Lu-PSMA-617 in Patients Previously Treated with EBRT for Oligometastatic Disease
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| Daniel Rosen, MD, PhD
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| Daniel Rosen reported that prior metastasis-directed external beam radiotherapy to bony oligometastases did not meaningfully worsen hematologic toxicity in mCRPC patients later treated with Lu‑PSMA‑617. In 70 such patients, no grade 3+ hematologic events occurred, grade 1–2 cytopenias were manageable, and over 60% completed all six Lu‑PSMA‑617 cycles, with similar completion and toxicity rates regardless of receiving one versus multiple prior radiation courses, supporting the tolerability of this treatment sequence and motivating studies of synchronous EBRT plus Lu‑PSMA‑617.
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| Clinical Outcomes Among Patients Treated with 177Lu-PSMA-617 and EBRT for Oligometastatic Prostate Cancer
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| Mai Anh Huynh, MD, PhD
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| Mai Anh Huynh reported registry data on 88 men with metastatic prostate cancer treated with 177Lu‑PSMA‑617 plus ablative external beam radiotherapy to all visible oligometastatic sites, showing a median overall survival of 20.1 months and a PSA50 response rate of 55.7%. Neither baseline PSA nor number of bone metastases clearly predicted survival, but there was a trend toward better outcomes when total metastatic burden was ≤5, suggesting that selectively combining metastasis-directed EBRT with 177Lu‑PSMA‑617 in oligometastatic patients may enhance disease control and merits prospective validation.
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| RPT Clinical Trials — An Investigator and Drug Development Perspective
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| Scott Tagawa, MD, MS, FACP, FASCO
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| Scott Tagawa highlighted how investigator‑initiated radiopharmaceutical trials can drive innovation in PSMA‑targeted agents like J591 and 177Lu/225Ac constructs, but require substantial institutional expertise, manufacturing capacity, regulatory navigation, and diversified funding. He used the decades‑long development of radiolabeled J591 and the evolving cooperative group PSMA trial portfolio to illustrate that, while RPT INDs can sometimes be more tractable and enable creative combinations, real‑world success hinges on coordinated drug production and distribution, multi‑center logistics, and close collaboration between academia and industry.
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| Industry Perspective and Regulatory Challenges for RPT Clinical Trials
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| Michael Morris, MD
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| Michael Morris reviewed how PSMA‑targeted radioligand therapy has rapidly expanded on the back of strong biologic rationale, a growing global trial pipeline, and landmark studies like VISION that established 177Lu‑PSMA‑617 as a standard in PSMA‑positive mCRPC. He emphasized that most RPT trials remain early phase, that regulatory oversight in the U.S. spans multiple oncology and radiation-focused groups and is still evolving, and that dose optimization must balance radiation safety with the real clinical risk of undertreating advanced cancer rather than simply importing external beam constraints.
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| Navigating Hematologic and Renal Dysfunction in RPT for Prostate Cancer
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| Russell Szmulewitz, MD
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| Russell Szmulewitz emphasized that while radium‑223 and 177Lu‑PSMA‑617 are established options for metastatic prostate cancer, they require careful use in patients with limited marrow reserve and baseline renal insufficiency. He highlighted strong efficacy data but frequent cytopenias, emerging long‑term renal and marrow risks, and offered practical blood count and kidney-based thresholds to guide dose modification and safe delivery of radiopharmaceutical therapy.
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| Toward Consensus in Lu-177 RPT Dosimetry: Comparing Multi-Timepoint and Single-Timepoint Imaging in Clinical Implementation
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| Siju George, PhD
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| Siju George compared multi-timepoint (MTP) versus single-timepoint (STP) imaging for Lu‑177 dosimetry, showing that MTP remains the most accurate but is resource‑intensive and harder to implement routinely. Carefully chosen STP protocols can approximate MTP accuracy while greatly reducing patient and departmental burden, supporting wider adoption of patient‑specific dosimetry in clinical practice.
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