68Ga-PSMA-11 PET Imaging Poised to Be Useful Management Tool in Biochemically Recurrent Prostate Cancer

Wolfgang Fendler, MD

The identification of disease via 68Ga-PSMA-11 PET imaging led to management changes in patients with biochemically recurrent prostate cancer, according to results of a prospective, multicenter trial.

In the study, investigators sought to determine the impact of 68Ga-PSMA-11 PET/CT on management of biochemically recurrent prostate cancer. Intended management changes occurred in 68% of patients and were implemented in 78% of patients; the intended change was considered major in 46% of patients.

Results also showed that management pathway aligned with 68Ga-PSMA-11 PET/CT findings and toward systemic therapy or combination approaches for metastatic disease at 44% and 69%, respectively. Moreover, the perceived site of disease was unknown in 68% of patients pre-PET and in 29% of patients post-imaging. Additionally, 150 intended diagnostic tests were prevented by 68Ga-PSMA-11 PET imaging, such as CT (29%) and bone Scans/NaF-PET (35%).

“I see [this imaging test having a] huge impact in the early stages and biochemical recurrence, where imaging becomes a central part of the management of patients,” said lead study author Wolfgang Fendler, MD.

In an interview with OncLive, Fendler, of the Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at University of California, Los Angeles, highlighted the potential impact 68Ga-PSMA-11 PET imaging may have on the treatment of patients with biochemically recurrent prostate cancer.

OncLive: Could you provide some background on this trial?

Fendler: 68Ga-PSMA-11 PET is an imaging modality. It is a whole-body scan for patients with prostate cancer and is very easy to be performed. Patients received an intravenous injection of a radionuclide before they were imaged. Afterwards, they had a whole-body imaging done for about 20 to 30 minutes. The image shows us where the prostate cancer is located in the body and can be used as an imaging or staging modality at initial diagnosis, or by clinical recurrence, in patients. The imaging locates the cancer for the physician to make further decisions.

What is it about this imaging modality that has made the community so excited?

There was a huge clinical need [for this type of imaging]. Blood tests show that the patient’s prostate-specific antigen is rising and then the cancer recurs. The disease is usually located in the pelvis; however, it is not possible to locate [the exact location of] this cancer.

68Ga-PSMA-11 PET is the first modality among other novel imaging tests and is one of the most sophisticated imaging tests. That is why it is being approached as a very promising imaging test.

What were the results that were presented at the 2020 Genitourinary Cancers Symposium?

We have shown before that the 68Ga-PSMA-11 PET imaging test shows prostate cancer lesions in patients with a rising tumor marker level in about 75% of patients and is very accurate. Now, we went one step further and assessed in a larger patient population [to see] whether or not this imaging test can impact management decisions.

We have assessed 382 patients on whether or not the intended management before the imaging test was done changed after seeing the results of the imaging test. This was assessed using questionnaires that were sent to the referring physicians. They were asked the following questions]: “What is your intended management before doing the imaging test? What is your intended management [after receiving the report]?” and a few months later, “Did you follow this management?”

Using questionnaires, we could show that the imaging test results and the change in the clinical management was found in two-thirds of patients and about half of all patients, respectively. There was either a new type of treatment being added or the treatment modality was completely changed. The study is going into more detail on what types of changes we see in patients and the types of management that follow what we see in imaging. For example, if it is a local disease, physicians tend to change the management to be more local. If there is no disease, they tend to change it to no treatment at all, and if it is a systemic disease then physicians change to systemic or multimodal treatment.

To what extent did 68Ga-PSMA-11 PET alter management of heavily recurring prostate cancer?

The change was in 68% of patients with any change in management after 68Ga-PSMA-11 PET imaging. About [48% of physicians considered an intended change and patients were given] a different type of treatment that was not considered before.

The type of changes we saw were an addition of chemotherapy in a patient who had a disease or lesion that was outside of the usual operating field. Typical changes also included an addition of radiation therapy in patients who had lymph nodes detected in the pelvis, with localized disease often undergoing additional radiation therapy to be more effective.

How close are we to FDA approval of 68Ga-PSMA-11 PET? What are the next steps?

There are several entities actively working on FDA approval of 68Ga-PSMA-11 PET. I would expect [it to be approved] within 1 year.

If the imaging test is approved, this means it is also becoming available and will be used more often. Before decisions are being made, most patients will undergo additional imaging for the physician and the patient to be informed about further management.

What is the rationale for this type of modality and how it is going to meet the unmet need?

This imaging test adds the location [of the tumor] and gives other information that is relevant in the clinical setting. The reason for this is that a lot of the available treatments need the location of the tumor. For example, we need to know which part of the body to apply radiation. The same goes for surgery; we need to know the [exact location] of the tumor. This is a specific need that the imaging test can fill to help physicians and patients to improve future regimens.

Is there anything else about your research that you would like our audience to know about?

Our research was focused on the change in management after this imaging test. It is very important as the next step to show a positive impact on what happens to the patient afterward, as well as the outcome and time until a patient shows another recurrence of the disease. There are several ongoing trials assessing this imaging test in a randomized fashion in comparison with the standard, which is looking at the benefit for the patient.

Wolfgang F, Ferdinandus J, Calais J, et al. Impact of 68Ga-PSMA-11 PET on the management of biochemically recurrent prostate cancer in a prospective single-arm clinical trial. J Clin Oncol. 2020;38(suppl 6; abstr 292). doi: 10.1200/JCO.2020.38.6_suppl.292