At GU New York 14th annual Interdisciplinary Prostate Cancer® and Other Genitourinary Malignancies, Phillip J. Koo, MD, highlighted the ability of next-generation imaging to alter the management of patients with prostate cancer.1
Koo, head of Diagnostic Imaging, Northwestern Department of Oncology Physician Government, MD Anderson Banner Cancer Center, Phoenix, Arizona, commented on featuring next-generation imaging; modern image producers, such as those targeting PSMA; and how these novel imaging techniques are “here to stay” in the prostate cancer paradigm.
The benefits of next generation imagery
While conventional imaging techniques – such as bone scans, CT, or MRI – date back to the 1970s, there are limitations in their use. For example, Koo noted that while bone scans are widely available and help identify bone lesions, they rarely identify asymptomatic disease or positively identify disease without it. High PSA. Similarly, although CT scans can follow a treatment response and detect metastasis, they cannot detect recurrent tumors and rely on size for nodal assessment, which can lead to poor sensitivity.
So, this is why there has been a shift in the image of the next generation. In particular, this strategy could allow clinicians to see things they could not see using conventional imaging.
“It’s almost like the difference between high definition TV compared to your standard TV,” Koo explained. “And we all recognize [that] with high def, it ‘s just amazing how much more you see and how well that grows. ”
In addition, he said, a number of unique imaging techniques have emerged that may allow high-resolution digital images to be obtained, which may be able to introduce new opportunities to burden disease assessment more accurately. However, there is a lack of consistency or practical use of next-generation imaging in prostate cancer.
Next-generation imaging works by taking advantage of the specific biological aspects of prostate cancer carcinogens. Molecular imaging probes, many of which are already in clinical or under-applied use, can be divided into imaging with increased cell metabolism, those targeting prostate cancer-specific proteins and receptor molecules, and those targeting attachment of the bone mat adjacent to metastases to the bone. Thus, increased metabolism and vascular changes in prostate cancer cells can be assessed with radiolabled analogs of choline, acetate, glucose, amino-acids, and nucleotides, Koo explained.
Types of pictures of the next generation
One given Koo example of imaging was the next-generation 18F-fluciclovine. Approved by the FDA in 2016, 18F-fluciclovine is a synthetic amino acid PET imaging agent that has proven to be able to identify amino acid transporters, which have been proven to be regulated in many cancer cells, he explained. Furthermore, because the radiotracer has not been metabolized or introduced into newly synthesized proteins, it may not inhibit normal protein synthesis.
“When the data was first reported in patients with biochemical relapse with a PSA level lower than or equal to 0.79, it had a detection rate of 41% which is quite surprising given that the PSA level is higher. low. That’s why it created so much happiness, that we were able to better image disease at biochemical recycling, ”said Koo.2
Next, clinicians have moved into the evaluation of PSMA PET technology. PSMA is a membrane protein that has been proven to have excessive overexpression in prostatic tissue but low sensitivity in normal tissue. Koo explained that high image quality could be achieved with PSMA PET due to the uptake of PSMA ligand into prostate cancer tumor cells. PET PSMA producers currently under review include 68Ga PSMA and 18F-DCFPyL PSMA; however, of course, no single image producer has yet been FDA approved.
Next generation imagery versus conventional imaging
In a prospective, single-center, open-label, single-arm comparative study, Michael S. Hoffman, MD, and colleagues compared 18F-fluciclovine and PSMA PET-CT scans for bio-recycling chemical prostate cancer after radical prostatectomy in patients with low PSA concentrations (<2.0 ng / mL).
The researchers found that, among the 50 participants, detection rates were significantly lower with 18F-fluciclovine PET-CT (n = 13 [26%]; 95% CI, 15% -40%) and PSMA PET-CT (n = 28 [56%]; 95% CI, 41% –70%), with an odds ratio (OR) of 4.8 (95% CI, 1.6–19.2; P. = .0026) at the patient level. They concluded that PSMA should be the PET detection option when considering PET-CT imaging for subsequent treatment management decisions in patients with prostate cancer and post-biochemical recurrence. radical prostatectomy and low PSA density.3
“The accuracy was much better than standard images, [which was] that’s not surprising, and they had a greater treatment effect, ”said Koo. “It also had fewer uncertain results. So that’s something I think is very important: Testing images with less equivalent results is more powerful … hopefully this will eliminate that hedge in the future for radiation and nuclear medicine. “
Translating next generation images into practice
With all that data, Koo indicated that it led to a “day of remembrance” in December 2020: The FDA approved the first PSMA-targeted PET imaging drug for men with prostate cancer.
“[The approval] in fact there were 2 marks. No. 1, its indications were for use in patients with biochemical relapse, which we were used to. But the biggest difference for this consent is that it was granted to patients at the first diagnosis, ”said Koo. “So he says it is indicated for suspected prostate cancer metastases, which may have been treated with surgery or radiation. This was a pre-defined treatment, which was new to the next-generation image producers. “
Before concluding, Koo noted that next-generation images do not replace pathology: “PET CT cannot detect that high level of detail disease in these patients. , so we have to separate the 2, because I often see that assuming. when it comes to pet images. ”
However, Koo added, the images of the next generation are here to stay. “For those in the opposition audience, I suggest you start getting a little more comfort each year as it doesn’t go anywhere. ”
References
1. Koo PJ. Imaging of the next generation of prostate cancer. Presented at: 14th Annual New York GU Congress; March 12-13, 2021.
2. Bach-Gansmo T, Nanni C, Nieh PT, et al. Multisite Knowledge of the Safety, Diagnosis, and Diagnostic Performance of Fluciclovine (18 F) Emit Positron Tomography / Computed Tomography Imaging in the biopsy of recurrent biochemical prostate cancer. J Urol. 2017; 197 (3 Pt 1): 676-638. doi: 10.1016 / j.juro.2016.09.117.
3. Calais J, Ceci F, Eiber M, et al. 8F-fluciclovine PET-CT and 68Ga-PSMA-11 PET-CT in patients with early biochemical recurrence after prostatectomy: prospective, single-center, single-arm comparative imaging test. Lancet Oncol. 2019; 20 (9): 1286-1294. doi: 10.1016 / S1470-2045 (19) 30415-2