How Does Quantitative Data Help in Patient Selection for 177Lu-PSMA-617 Theranostics?

Ken Ngai
Ken Ngai
4/1/25 8:27 AM

A review of recent literature shows promising evidence: Total tumor burden (TTB) metrics can aid physicians in their decision-making process to determine who will benefit most from 117Lu-PSMA-617 radioligand therapy (RLT).

Why It Matters: Access to 177Lu-PSMA-617 Therapy Is About to Expand

Prostate cancer is one of the most commonly diagnosed cancers. Metastatic castration-resistant prostate cancer (mCRPC) is the most aggressive and difficult-to-treat form of prostate cancer.

In 2022, the FDA approved the use of Pluvicto® 177Lu-PSMA-617 RLT to treat patients with prostate-specific membrane antigen (PSMA)-positive mCRPC who have been treated with androgen receptor (AR) pathway inhibition and taxane-based chemotherapy.1 However, multiple trials in progress are investigating the use of 177Lu-PSMA-617 in earlier-stage metastatic prostate cancers.2 This means that access to this therapy may be opened to a much broader population in the near future.

When 177Lu-PSMA-617 therapy is available earlier in a patient’s disease progression, concerns over toxicity and patient side effects increase due to the patient’s longer life expectancy. There are also more treatment options available at this stage of treatment. Both factors make it even more important to select the patients most likely to benefit from this treatment. As Thomas Hope, MD, Professor in Residence and Vice Chair of Operations and Strategy at University of California, San Francisco, recently explained, “... having five years of dry mouth is very different than having eight months of dry mouth, et cetera.”3

 

A Case for Using TTB in 177Lu-PSMA-617 Theranostics Patient Selection

A review of recent research, summarized below, shows agreement on two key points:

  1. Patient response to 177Lu-PSMA-617 therapy is not homogenous in the mCRPC population. For this reason, a prognostic biomarker is needed to predict which patients will respond well to this therapy.
  2. Quantitative values corresponding to a patient’s TTB can be used as a PET-based biomarker for 177Lu-PSMA-617 patient selection.

Recent Literature Supporting TTB for 177Lu-PSMA-617 Theranostics Patient Selection4

Publication

Highlight

Rahbar Nikoukar L. 2025, Nuklearmedizin.

“It was also observed that a higher SUVmean of all tumor lesions at baseline in 68Ga-PSMA-PET-CT is associated with a better PFS and OS after PSMA-therapy in our study.”

“The present study confirms that pretherapeutic PSMA-PET before RLT with 177Lu PSMA has a prognostic value. Best-validated parameter in this study as on prospective datasets is SUVmean of all tumor lesions.”

Kuo PH et al. 2024, Radiology.

“Baseline 68Ga-PSMA-11 PET/CT whole-body tumor SUVmean was the best predictor of 177Lu-PSMA-617 efficacy in participants in the VISION trial. Improvements in rPFS and OS with 177Lu-PSMA-617 plus SOC were greater among participants with higher whole-body tumor SUVmean, with evidence for benefit at all SUVmean levels.”

SNMMI Consensus Statement on Patient Selection and Appropriate Use of 177Lu-PSMA-617 Radionuclide Therapy. 2023.

“Secondary analysis of both the VISION and TheraP trials has shown that patients with higher whole body (WB) PSMA SUVmeans on baseline PET have better outcomes with 177LuPSMA-617”

Joint EANM/SNMMI Procedure Guideline for the Use of 177Lu-labeled PSMA-Targeted Radioligand-Therapy. 2023.

“Prognostic factors associated with poor treatment outcome: … 2. Imaging findings: Presence of visceral metastases, presence of bone-metastases vs. LN-metastases only, extent of bone metastases, total tumor volume, high [18F]FDG-uptake.”

Pathmanandavel S et al. 2023, JNM.

“... accurate assessment of change in TTV [total tumor volume] visually can be difficult, especially in high-volume disease, and quantitative PET analysis may become an important tool in PSMA-targeted therapy.”

Soehl K et al. 2023, JNM.

“Total tumor burden metrics such as volume and TLU [total lesion uptake] showed better predictive power than SUV in the hottest lesion or total lesion SUV mean.”

Karimzadeh A et al. 2023, JNM.

“In this study, no significant correlation between SUVmax and treatment response or OS was found. However, a rising whole-body SUVmean correlated with survival and treatment response, supporting our hypothesis that insufficient PSMA ligand uptake in lesions, in general, might play a crucial role for the outcome of PSMA RLT.”

John N et al. 2023, JNM.

“This study relied on quantitation of SPECT data rather than visual assessment. This reliance on quantitation for effective predictive and response biomarkers in molecular imaging is increasing, including the highly valuable SUVmean on screening 68Ga-PSMA PET for 177Lu-PSMA therapy. However, quantitation is not the standard of care and is time-intensive. Further work is needed to streamline quantitation for widespread adoption into routine practice.”

Buteau JP et al. 2022 Lancet Oncol.

“In men with metastatic castration-resistant prostate cancer, PSMA-PET SUVmean was predictive of higher likelihood of favourable response to [177Lu]Lu-PSMA-617 than cabazitaxel…”

Gafita A et al. 2021, Lancet Oncol.

“...externally validated nomograms that are predictive of outcomes after 177Lu-PSMA in patients with mCRPC might help in clinical trial design and individual clinical decision making, particularly at institutions where 177Lu-PSMA is introduced as a novel therapeutic option.”

 

  1. For full details on the approved use of 177Lu-PSMA-617, see the package insert and NCCN guidelines.
  2. Ramnaraign B, Sartor O. PSMA-Targeted Radiopharmaceuticals in Prostate Cancer: Current Data and New Trials. Oncologist. 2023;28(5):392-401.
  3. Hope T. Real-world Experiences Associated with Treating Patients With Lutetium-177 PSMA in a High-volume Care Center - Thomas Hope. UroToday. March 2023.
  4. For full citations, see the end of this blog post.

 

 

How Can You Access Quantitative Data for Theranostics Patient Selection?

As multiple publications suggest, quantitative TTB metrics are emerging as an important tool to aid physicians in determining who will benefit the most from 177Lu-PSMA-617 therapy. But is accessing this data clinically feasible?

To calculate TTB metrics, you first have to segment all lesions on an image. With increasing patient volumes and personnel shortages, new automated tools are needed to help calculate TTB metrics.

Software tools are available that provide efficient whole-body lesion segmentation and automated calculation of whole-body SUVmean. This enables clinicians to consider the most relevant clinical data when making critical patient care decisions, even when resources are limited.

 

Full Citations
Theranostics, Molecular Radiotherapy, Radiopharmaceutical Therapy, LesionID Pro
Ken Ngai
Written by Ken Ngai

Ken Ngai is a clinical engineer at MIM Software. He works closely with different teams at MIM Software to understand customers’ needs and opportunities, with a focus on PET Oncology and General Nuclear Medicine.

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