About

Magnus Dahlbom has spent his entire research career in the various aspects of radionuclide imaging and in-vivo quantification methods using radioisotopes, both clinically and in research. He has worked on all aspects of PET imaging, ranging from developmental work on front-end detectors and electronics to the development of quantitative imaging techniques. His primary focus has been on human radionuclide imaging, developing imaging methods such as whole-body PET imaging, 3-D image reconstruction, and correction methods to allow accurate quantification, including scatter and attenuation correction. Recently, with the development of radionuclide therapies, his research has shifted towards theranostics—the combination of targeted cancer radionuclide imaging and radionuclide therapy. His particular interest is in using functional imaging (PET and SPECT) combined with anatomical imaging to accurately determine the radiation dose to tumors and normal organs following the administration of radioactive therapeutic or imaging agents. His work involves serial imaging to assess uptake and excretion of radioactive agents, enabling estimation of radiation doses to individual patients, with the goal of optimizing injected doses to maximize tumor doses while minimizing damage to normal tissue and organs. This work includes the development of image processing techniques and computational methods for radiation dose estimation.

Research topics

• Medicine
• Internal medicine
• Nuclear medicine
• Cancer research
• Oncology
• Urology
• Pathology
• Engineering ethics
• Medical physics
• Surgery
• Immunology
• Engineering
• Physical therapy
• Endocrinology

Selected publications

• Phase 2 Prospective Trial of Retreatment with [ ¹⁷⁷ Lu]Lu-PSMA-617 Molecular Radiotherapy for Metastatic Castration-Resistant Prostate Cancer—RE-LuPSMA

  Journal of Nuclear Medicine · 2026-02-12

  articleOpen access

  [¹⁷⁷Lu]Lu-PSMA-617 radiopharmaceutical therapy has been approved for the treatment of patients with metastatic castration-resistant prostate cancer for up to 6 cycles. Unfortunately, this treatment is not curative and patients experience relapse, even after initially favorable responses. When this occurs, patients have limited treatment options. Readministration of [¹⁷⁷Lu]Lu-PSMA-617 in patients who previously benefited from therapy and had limited toxicity seems to be a promising option, with retrospective studies reporting favorable outcomes. <b>Methods:</b> RE-LuPSMA is an investigator-initiated, single-arm, single-center, open-label, phase 2 clinical trial designed to study the efficacy and safety of rechallenge therapy using [¹⁷⁷Lu]Lu-PSMA-617 in patients whose disease progressed after responding well to a previous regimen of [¹⁷⁷Lu]Lu-PSMA-617. This study plans to enroll 40 patients with progressive metastatic castration-resistant prostate cancer who previously completed 4–6 cycles of [¹⁷⁷Lu]Lu-PSMA-617 with a favorable response (i.e., ≥50% decrease in prostate-specific antigen [PSA] level at any point during the first [¹⁷⁷Lu]Lu-PSMA-617 regimen). After the first regimen of [¹⁷⁷Lu]Lu-PSMA-617, patients must meet VISION trial criteria on a prostate-specific membrane antigen (PSMA) PET/CT scan within 8 wk of the planned first cycle of rechallenge therapy. After enrollment, participants will receive up to 6 additional cycles of [¹⁷⁷Lu]Lu-PSMA-617 (7.4 GBq every 6 wk). The primary endpoint is 12-mo overall survival (OS), measured from the start of rechallenge therapy. The study will have 80% power to detect a difference between the null hypothesis of 50% OS at 12 mo and the study hypothesis of 71% OS at 12 mo. Secondary endpoints include adverse-event rates, PSA response rates (proportion of patients with a decrease of 50% or greater in PSA level), biochemical progression-free survival (defined as the time until PSA level increases 25% and 2 ng/mL above the nadir), radiographic progression-free survival, and quality-of-life changes (measured using Functional Assessment of Cancer Therapy–Radionuclide Therapy and Brief Pain Inventory–Short Form). Enrollment began in August 2024, with a planned study duration of 45 mo.

  PublisherOA PDFDOI

• Randomized Phase 2 Trial of an Extended and Flexible Dosing Schedule of ¹⁷⁷Lu-PSMA Molecular Radiotherapy in Patients with Metastatic Castration-Resistant Prostate Cancer (FLEX-MRT): Study Protocol

  Journal of Nuclear Medicine · 2025-08-28 · 6 citations

  articleOpen access

  [¹⁷⁷Lu]Lu-PSMA-617 radiopharmaceutical therapy has been approved for the treatment of men with metastatic castration-resistant prostate cancer (mCRPC) using a fixed dosing schedule of once every 6 wk for up to a total of 6 doses. We hypothesized that patients may benefit from a flexible and extended dosing schedule, up to 12 doses with potential “treatment holiday” periods. <b>Objective:</b> The objective of this study is to determine the 2-y survival rate of patients with mCRPC treated with an extended and flexible dosing schedule of [¹⁷⁷Lu]Lu-PSMA-617 therapy in comparison to patients treated with the standard fixed dosing schedule of a maximum of 6 treatment cycles once every 6 wk. <b>Study Design:</b> The FLEX-MRT trial is an investigator-initiated prospective phase 2, parallel group, randomized, controlled, open-label, single-center trial in men with mCRPC to determine the efficacy of a flexible and extended dosing schedule of [¹⁷⁷Lu]Lu-PSMA-617 therapy. Key inclusion criteria are patients eligible for Pluvicto (i.e., prior androgen receptor signaling inhibitors, prior chemotherapy, PSMA PET VISION criteria). Key exclusion criteria are prior [¹⁷⁷Lu]Lu-PSMA-617 therapy and less than 6 wk since last myelosuppressive therapy. The trial aims to centrally randomize 90 patients in a 1:1 ratio to 2 treatment arms. In the control arm, patients will be treated with the approved standard dosing schedule (<i>n</i> = 45). In the investigational arm, patients will be treated with up to 12 cycles and with potential treatment holidays depending on response (<i>n</i> = 45). Response assessment is based on SPECT/CT at each cycle and on PSMA PET/CT during treatment holiday periods (every 12 wk). Primary endpoint is the 2-y survival rate. Survival is calculated from the date of the first cycle of [¹⁷⁷Lu]Lu-PSMA-617 therapy. Secondary endpoints include safety by Common Terminology Criteria for Adverse Events and dosimetry and determination of overall and progression-free survival (evidence of progression as defined by radiographic, prostate-specific antigen level, or clinical progression, or death from any cause).

  PublisherOA PDFDOI

• A randomized phase 2 trial of flexible and extended dosing of ¹⁷⁷ Lu-PSMA-617 molecular radioligand therapy in mCRPC (FLEX-MRT): Trial in progress update.

  Journal of Clinical Oncology · 2025-05-28

  article

  TPS5121 Background: The U.S. Food and Drug Administration (FDA) approved 177 Lu-PSMA-617 radiopharmaceutical therapy (RPT) for patients with metastatic castration-resistant prostate cancer (mCRPC) with a fixed dosing schedule: Six cycles of 7.4 GBq administered in six-week intervals. However, a patient-tailored more flexible and extended dosing schedule of 177 Lu-PSMA RPT may increase treatment efficacy. In this randomized trial in men with mCRPC, we aim to determine the efficacy of a response-based flexible dosing schedule of 177 Lu-PSMA-617 RPT administered up to 12 treatment cycles compared to the current standard of care. Methods: This is an investigator-initiated prospective phase 2, open-label, randomized, controlled, parallel group, single-center trial. The aim is to assess the 2-year survival rate in mCRPC patients treated with a flexible dosing schedule of 177 Lu-PSMA RPT up to 12 cycles in comparison to the fixed dosing schedule of 6 cycles. Patients with progressive mCRPC post-ARSI, post taxane-based chemotherapy are eligible by PSMA positron emission tomography (PET) VISION trial criteria. Exclusion criteria include prior RPT and less than 6 weeks since the last myelosuppressive therapy. We hypothesized 2-year survival rates of 55% in the investigational group and 30% in the control group. A two-sided log rank test with an overall sample size of 90 subjects (45 treatment group, 45 control group) achieves 80.3% power at a 0.05 significance level to detect a hazard ratio of 0.050. Patients will be randomized in a 1:1 ratio: The investigational arm is treated with up to 12 cycles including potential “treatment holidays” depending on the treatment response (n=45); the control arm receives 6 cycles administered in six-week intervals (n=45). Imaging response to RPT is assessed using 177 Lu-PSMA-617 SPECT/CT after each cycle and PSMA PET/CT during treatment holidays (every 12 weeks), respectively. In the investigational arm, RPT will be re-started after a treatment holiday if the patient experiences a ≥25% PSA progression and an imaging progression according to the Response Evaluation Criteria in PSMA PET/CT (RECIP). Primary endpoint is the 2-year survival rate calculated from the date of the first cycle of RPT. Secondary endpoints include safety by Common Terminology Criteria for Adverse Events (CTCAE) and dosimetry, and determination of overall and progression-free survival (evidence of progression as defined by either radiographic, PSA, or clinical progression, or death from any cause). The FLEX-MRT trial has been approved by the FDA (IND #168362), and the UCLA IRB (#23-000931). The trial is registered on ClinicalTrials.gov (NCT06216249). The FLEX-MRT trial is currently recruiting. Start of enrollment was in August 2024. As of January 27th, 2025, 19 patients have been enrolled. Clinical trial information: NCT06216249 .

  PublisherDOI

• ¹⁷⁷ Lu-Prostate-Specific Membrane Antigen Neoadjuvant to Stereotactic Ablative Radiotherapy for Oligorecurrent Prostate Cancer (LUNAR): An Open-Label, Randomized, Controlled, Phase II Study

  Journal of Clinical Oncology · 2025-11-12 · 13 citations

  articleOpen access

  PURPOSE Progression after metastasis-directed therapy via stereotactic body radiotherapy (SBRT) for oligorecurrent hormone-sensitive prostate cancer (orHSPC) is common. We aimed to assess whether the addition of neoadjuvant prostate-specific membrane antigen (PSMA)–targeting radioligand therapy to SBRT would improve outcomes. METHODS The LUNAR trial was a single-center, randomized, open-label, controlled phase II trial conducted at the University of California, Los Angeles. Eligible participants had orHSPC as determined by the presence of one to five lesions identified on PSMA positron emission tomography/computed tomography (PET/CT). After stratifying by stage (N1/M1a v M1b) and lesion count (1 v 2-3 v 4-5), we randomly assigned patients 1:1 to receive SBRT to all lesions or two cycles of 177 Lu-PNT2002 (6.8 GBq/cycle, 2 weeks apart) followed by SBRT to all lesions. The primary end point was progression-free survival (PFS), defined by PSMA PET/CT, salvage hormonal therapy, or death. PSMA PET/CT was acquired systematically at prostate-specific antigen progression and/or 12 months after SBRT. All analyses were done in the intention-to-treat population. The study is registered with ClinicalTrials.gov (identifier: NCT05496959 ). RESULTS From September 2, 2022, to November 9, 2023, 92 patients were randomly assigned (SBRT n = 47 and 177 Lu + SBRT n = 45), with 87 evaluable patients (SBRT n = 42 and 177 Lu + SBRT n = 45). At a median follow-up of 22 months, the addition of 177 Lu to SBRT significantly improved PFS (17.6 months [95% CI 15 months to not reached] v 7.4 months [95% CI, 6.0 to 13.5 months]; hazard ratio, 0.37 [95% CI, 0.22 to 0.61], P &lt; .0001). The only grade 3 adverse events were lymphopenia (two patients [4.8%] in the SBRT group and three patients [6.7%] in the 177 Lu + SBRT group). Prognostic biomarkers for PFS were identified. CONCLUSION Compared with SBRT alone, the addition of 177 Lu-PNT2002 to SBRT significantly improved PFS in patients with orHSPC without an attendant increase in toxicity.

  PublisherDOI

• Application of a Hand-Held Czt-Based Gamma Camera for Pre-Clinical Intratherapeutic Imaging of ¹⁷⁷ Lu, ²²⁵ Ac, and ²¹² Pb

  2025-11-01

  article

  A small, portable gamma camera has been acquired for fast, easy, and quantitative imaging in preclinical radionuclide therapy studies. The camera uses a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$39 \times 39 \times 5 ~\text{mm}^{3}$</tex> Cadmium Zinc Telluride semiconductor crystal to produce <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$16 \times 16$</tex>-pixel images and can be equipped with a medium-energy high-resolution collimator, two low-energy collimators (high-sensitivity or high-resolution), or a pinhole collimator. The performance of the camera was assessed for imaging of the therapeutic radionuclides <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">177</sup>Lu, <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">225</sup> Ac, and <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">212</sup> Pb using phantom and in-vivo studies. All collimators were used for <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">177</sup>Lu, while imaging of <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">225</sup> Ac and <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">212</sup> Pb utilized only the medium-energy collimator and the pinhole collimator due to the abundance of high-energy photons. A mouse-like phantom was manufactured through 3D printing with fillable cavities for the liver and a subcutaneous tumor.

  PublisherDOI

• Studienprotokoll der laufenden FLEX-MRT Studie: Randomisierte Phase-2-Studie zur FLEXiblen und erweiterten Dosierung der [177Lu]Lu-PSMA-617 Molekularen RadioTherapie (FLEX-MRT) in Patienten mit mCRPC

  Nuklearmedizin - NuclearMedicine · 2025-03-01

  article
  PublisherDOI

• Study protocol: Phase 2 trial of re-treatment with 177Lu-PSMA-617 molecular radiotherapy for metastatic castration resistant prostate cancer (RE-LuPSMA trial).

  Journal of Clinical Oncology · 2025-05-28

  article

  TPS5110 Background: The phase III VISION trial demonstrated that 177 Lu-PSMA-617 radioligand therapy (RLT) improved overall survival (OS) in patients with metastatic castration-resistant prostate cancer (mCRPC) who previously received taxane-based chemotherapy and at least one androgen receptor pathway inhibitor (ARPI). As a result, 177 Lu-PSMA-617 therapy has been approved in this patient population by the U.S. Food and Drug Administration for up to six cycles (7.4 GBq per cycle) every 6 weeks. Unfortunately, this treatment is not curative and patients relapse even after initially favorable responses. When this occurs, patients have limited treatment options given they have had prior chemotherapy and ARPI regimens. Re-administration of 177 Lu-PSMA-617 in patients who previously benefited from therapy and had limited toxicity seems to be a promising option. Small retrospective studies have reported favorable outcomes. Further prospective data with larger sample sizes are needed to confirm these findings. Methods: RE-LuPSMA is an investigator-initiated, single-arm, single-center, open-label, phase 2 clinical trial (NCT06288113). This study plans to enroll 40 patients with progressive mCRPC who previously completed 4-6 cycles of 177 Lu-PSMA-617 therapy with a favorable response. Favorable response is defined as a prostate-specific antigen (PSA) decline ≥50% during the first regimen. Progression following the first regimen is defined using imaging or PSA (two consecutive PSA increases ≥3 weeks apart). Patients who received another line of prostate cancer therapy within two months of completing the first regimen of 177 Lu-PSMA-617 are excluded. Patients must meet PSMA PET/CT VISION criteria. PSMA PET/CT must have been completed within 8 weeks of the planned first cycle of re-challenge therapy. Upon enrollment, participants will receive up to 6 additional cycles of 177 Lu-PSMA-617 (7.4GBq every 6 weeks). Patients will follow-up every 6 months until 2 years from the end of re-challenge therapy. The primary endpoint is 12-month OS measured from the start of re-challenge therapy. The study will have 80% power to detect a difference between the null hypothesis of 50% and the study hypothesis of 71%. Secondary endpoints include adverse event rates, PSA response rates (proportion of patients with a PSA decrease of ≥50%), biochemical progression-free survival (time until PSA level increases 25% and 2 ng/mL above the nadir), radiographic progression-free survival, and health-related quality of life changes (measured using Functional Assessment of Cancer Therapy - Radionuclide Therapy [FACT-RNT] and Brief Pain Inventory [Short Form]). Enrollment has started with a planned study duration of 4 years of which subject accrual occurs in the first 12 months. Clinical trial information: NCT06288113 .

  PublisherDOI

• A free method for patient-specific 3D-VR anatomical modeling for presurgical planning using DICOM images and open-source software

  Methods · 2025-02-22 · 2 citations

  articleSenior author
  PublisherDOI

• A randomized phase 2 trial in progress of flexible and extended dosing of ¹⁷⁷Lu-PSMA-617 molecular radioligand therapy in mCRPC (FLEX-MRT).

  Journal of Clinical Oncology · 2024-06-01 · 1 citations

  article

  TPS5110 Background: The U.S. Food and Drug Administration (FDA) approved 177 Lu-PSMA-617 radioligand therapy (RLT) for patients with metastatic castration-resistant prostate cancer (mCRPC) with a fixed dosing schedule: Six cycles of 7.4 GBq administered in six-week intervals. However, a patient-tailored more flexible and extended dosing schedule of 177 Lu-PSMA RLT may increase treatment efficacy. No prospective data on such extended or abbreviated treatment schedule are available yet. In this randomized trial in men with mCRPC, we aim to determine the efficacy of a response-based flexible dosing schedule of 177 Lu-PSMA-617 RLT administered up to 12 treatment cycles compared to the current standard of care. Methods: This is an investigator-initiated prospective phase 2, open-label, randomized, controlled, parallel group, single-center trial. The aim is to assess the 2-year survival rate in mCRPC patients treated with a flexible dosing schedule of 177 Lu-PSMA RLT up to 12 cycles in comparison to the fixed dosing schedule of 6 cycles. Patients with progressive mCRPC post-ARSI, post taxane-based chemotherapy are eligible by PSMA positron emission tomography (PET) VISION trial criteria. Exclusion criteria include prior RLT and less than 6 weeks since the last myelosuppressive therapy. We hypothesized 2-year survival rates of 55% in the investigational group and 30% in the control group. A two-sided log rank test with an overall sample size of 90 subjects (45 treatment group, 45 control group) achieves 80.3% power at a 0.050 significance level to detect a hazard ratio of 0.4966. Patients will be randomized in a 1:1 ratio: The investigational arm is treated with up to 12 cycles including potential “treatment holidays” depending on the treatment response (n=45); the control arm receives 6 cycles administered in six-week intervals (n=45). Imaging response to RLT is assessed using 177 Lu-PSMA-617 SPECT/CT 24 h after each cycle and PSMA PET/CT during treatment holidays (every 12 weeks), respectively. In the investigational arm, RLT will be re-started after a treatment holiday if the patient experiences a ≥25% PSA progression and an imaging progression according to the Response Evaluation Criteria in PSMA PET/CT (RECIP). Primary endpoint is the 2-year survival rate calculated from the date of the first cycle of RLT. Secondary endpoints include safety by Common Terminology Criteria for Adverse Events (CTCAE) and dosimetry, and determination of overall and progression-free survival (evidence of progression as defined by either radiographic, PSA, or clinical progression, or death from any cause). The FLEX-MRT trial has been approved by the FDA (IND #168362), and the UCLA IRB (#23-000931). The trial is registered on ClinicalTrials.gov (NCT06216249). Start of enrollment is in February 2024. The study will last for 48 months of which subject accrual (entry) occurs in the first 12 months. Clinical trial information: NCT06216249 .

  PublisherDOI

• Swelling of the Right Arm During a Nuclear Medicine Therapy for Metastatic Pheochromocytoma

  AACE Clinical Case Reports · 2024-11-18 · 1 citations

  articleOpen access
  PublisherDOI

Frequent coauthors

• Johannes Czernin

  72 shared

• Christiaan Schiepers

  45 shared

• Sung‐Cheng Huang

  33 shared

• Michael E. Phelps

  31 shared

• Daniel Silverman

  Howard Hughes Medical Institute

  30 shared

• Carl K. Hoh

  University of California, San Diego

  27 shared

• Jérémie Calais

  Molecular Theranostics (United States)

  26 shared

• Nagichettiar Satyamurthy

  18 shared