BACKGROUND

Prostate cancer is the most commonly diagnosed cancer in Australia, approximately 24,000 Australians were diagnosed with prostate cancer in 2022. The median duration of response to medical castration is only 2 years and patients eventually develop resistance leading to disease progression and metastatic castration-resistant prostate cancer (mCRPC). 

STUDY OVERVIEW

TheraP is the first randomised trial comparing 177Lu-PSMA-617 (Lu-PSMA), a novel radioactive treatment, to the current standard-of-care chemotherapy called cabazitaxel for people with metastatic castration-resistant prostate cancer. These people had disease that had already progressed after standard chemotherapy.  

This unique treatment involved two distinct parts. Firstly, a PET scan is used to ‘map’ the cancer. This is done by injecting a radioactive molecule called gallium-68 attached to a small molecule that rapidly localises to prostate specific membrane antigen (PSMA) on the surface of prostate cancer cells in the body. The result is the cancer cells ‘light up’, showing exactly where the disease is and enabling identification of patients that may benefit from this new therapy. The second part is the therapy itself: the Lu-177 radionuclide is attached to a similar molecule used in the scanning process, and LuPSMA is administered to the patient, targeting the tumours and killing the cancer cells while minimising damage to surrounding tissue.   

The primary endpoint of the study was to compare the effects of the two treatments on change in PSA, a blood biomarker of prostate cancer. The results of the three-year follow up conclude a continued favourable response, defined by reduction of PSA by 50% or more, occurred in 66% of people assigned to receive Lu-PSMA compared to 37% with cabazitaxel.  Results of the trial also demonstrated the treatment had less severe side effects than chemotherapy. The survival of people assigned to LuPSMA was similar to cabazitaxel, a proven life-prolonging treatment. Survival was considerable shorter for people screened for the trial but for whom treatment was not suitable because PSMA uptake was low on initial scans (11 months compared to 18.8 months for those on trial treatments).

PARTICIPANTS

EXPERTISE

Conceived, designed and conducted in collaboration with ANZUP.​

CTC brought its expertise in operations and trial management, which included working with Australian Nuclear Science and Technology Organisation (ANSTO), to provide the unique radionucleotide Lutetium, which has a very short half life and required real-time planning, ordering and delivery to hospital nuclear medicine units, for synthesis with PSMA-11 for patient administration.  

FINDINGS

Three-year follow-up of the TheraP study provides compelling evidence that Lutetium-177 PSMA-617 is a new treatment option for people with prostate cancer, providing an alternative to cabazitaxel chemotherapy with better patient reported outcomes and lower side effects. 

The proportion of participants with a 50% or greater reduction in PSA was higher in the Lu-PSMA group (66%) than in the cabazitaxel group (33%).  

The time until the cancer worsened (progression-free survival), was approximately 60% longer in the Lu-PSMA group than in the cabazitaxel group. 

Survival time was similar in the two groups. 

Questions about how participants were feeling and doing showed that quality of life was better in the Lu-PSMA group than in the cabazitaxel group. 

DURATION

2018 - 2022

COLLABORATORS

ANZUP

FURTHER READING

Click here for downloadable .PDF >

See ANZCTR for full trial details >