Modeled clinical and economic outcomes of prostate-specific membrane antigen positron emission tomography (PSMA-PET) for the initial diagnosis and staging of patients with prostate cancer

Introduction: Advanced imaging modalities for the diagnosis and staging of prostate cancer have seen increased clinical utilization in the past several years, with PSMA-PET imaging showing particular promise to improve upon standard-of-care (CT, MRI, SPECT) imaging. Clinical studies in both newly-diagnosed and recurrent patient populations have demonstrated the accuracy and validity of PSMA-PET imaging agents to identify metastatic disease. Here we seek to better understand the longer-term impact of PSMA-PET imaging performance on newly-diagnosed patients and the healthcare system.

Methods: A published model that examined the longer-term clinical outcomes and economic utility of imaging modalities for the initial diagnosis and staging of prostate cancer patients was used for this research. The published model uses a decision tree to map the diagnostic and treatment pathways while a Markov process is used to model long-term outcomes of disease progression of treatment decisions following imaging procedures. The model assesses clinical and economic impacts of both diagnostic and treatment decisions over a lifetime horizon. Sensitivity and specificity from clinical studies of piflufolastat F18, flotufolastat F18, and Ga68-PSMA-11 for the initial diagnosis and staging of prostate cancer patients served as primary inputs into the model, as well as their respective costs. These advanced imaging approaches were compared against standard-of-care imaging comprised of a mix of CT, MRI, and SPECT. The model included clinical impact and costs of procedures and treatments; costs were inflation-adjusted to 2023 US dollars. Clinical outcomes of the model consisted of life-years (LYs) and quality-adjusted life-years (QALYs), while economic outcomes included net costs, incremental cost-effectiveness ratio (ICER), and net monetary benefit.

Results: Piflufolastat F18 generated the highest clinical impact, demonstrating 6.805 LYs and 5.334 QALYs, while flotufolastat F18 demonstrated the lowest clinical impact with 6.498 LYs and 5.016 QALYs; standard-of-care imaging resulted in 6.581 LYs and 5.119 QALYs. Estimated lifetime patient costs across all PSMA-PET imaging agents were similar, ranging from $172,205 for Ga68-PSMA-11 to $175,137 for piflufolastat F18. Relative to standard-of-care imaging, piflufolastat F18 was the most cost-effective with an ICER of $134,233. Meanwhile, flotufolastat F18 showed worse clinical outcomes and higher cost than standard-of-care imaging, which is a result of the majority read sensitivity that was reported in the flotufolastat F18 pivotal study LIGHTHOUSE showing performance that does not surpass the referenced performance of standard-of-care imaging modalities in the indicated scenarios. Overall, piflufolastat F18 demonstrated the highest net monetary benefit of $624,963 compared to standard-of-care imaging at $621,573.

Conclusions: Clinical outcomes and economic impact of PSMA-PET imaging when used for the initial diagnosis and staging of prostate cancer will differ depending on the PET agent that is used and its underlying performance. Piflufolastat F18 was estimated to positively impact patient outcomes the most, while outcomes for flotufolastat F18 were estimated to be worse than standard-of-care imaging. While lifetime net costs for patients having PSMA-PET for their initial diagnosis and staging are similar, piflufolastat F18 demonstrated superior cost-effectiveness compared to other PSMA-PET agents.