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Nasrin Ghesani: This is Nasrin Ghesani from Mount Sinai Hospital. I'm a nuclear medicine physician and today I will go over one very interesting case of excellent response to lutetium-177 therapy in a small volume, chemo naive patient.

Briefly, I'm going to go over the patient's background. Patient is a 71-year-old man who was diagnosed with prostate cancer in 2012 and he underwent radical prostatectomy. His pathology demonstrated Gleason 7 pT3aN0 disease. There was a presence of extracapsular extension and perineural infiltration. The margins were positive, but there was no seminal vesicle involvement or the lymph node metastasis. Associated PSA at the time of diagnosis was 10. He sustained biochemical recurrence in 2014. MRI of the prostate at that time was negative and he received IMRT to prostate bed.

In 2016, his PSA started rising and it was 4.68 at that time. Sodium fluoride PET-CT scan demonstrated uptake in the right glenoid process and L3 vertebral bodies suspicious for metastatic disease. He was started on bicalutamide and Lupron, and completed targeted RT to shoulder and spine given the oligometastatic recurrence. Due to slight rise in PSA, patient was started with abiraterone and prednisone in January 2018. In June of 2018, patient had a bout of paroxysmal fibrillation. Abiraterone was stopped in August 2018 following the episode of stroke. PSA was undetectable after his Lupron shot in August 2018. Patient had another episode of hemorrhagic and ischemic stroke in October 2018.

PSA suddenly started rising in February 2021, and at that time, imaging showed retrocrural lymphoid metastasis. He was initiated on Firmagon and Nubeqa in April 2021. In June 2021, PSA started rising, showing concern for metastatic castrate-resistant prostate cancer. PSMA PET in October 2021 demonstrated intense radiotracer uptake in the left supraclavicular lymph nodes, as well as in the posterior mediastinal right retrocrural, aortocaval, retrocaval, and right commonly iliac lymph node. This is the PSMA PET showing up increased uptake in the left supraclavicular lymph nodes, right retrocrural lymph nodes along the right pelvic sidewall, and there are several retroperitoneal lymph nodes.

At this point, a medical oncologist was considering several options for his treatment. Given his history of prior stroke, his medical oncologist thought he was not a good candidate for chemotherapy, and at this point his medical oncologist, who is actually the Chief Medical Officer of the Prostate Cancer Foundation, Dr. William Oh, referred patient to us to be treated for lutetium PSMA-617 therapy in November 2021. However, due to his chemotherapy naive status, he was not meeting criteria for enrollment in the expanded access program, and we thought of applying to FDA via named patient IND to make him eligible for this treatment. We received approval from FDA and he started his PSMA-617 therapy in January 2022.

Patient received four cycles of Lutetium PSMA therapy starting from January 2022 to August 2022. Due to production related issues, Novartis had stopped supplying therapy doses in May and June of 2022, so his therapy was further delayed until July and August. As you can see in the bottom, his PSA at the time of initiation of therapy was 5.8, and soon after receiving treatment, his PSA started declining. In August of 2022, his PSA was undetectable. These are serial post-therapy scans performed with lutetium PSMA. As you can see, the resolution is not as good as PSMA PET, but you can still see some lymph nodes in the left supraclavicular region, retrocrural, and retroperitoneal region. This is his first PSMA post-therapy scan, and by the time he came for the fourth post-PSMA therapy scan, there was no evidence of residual tumor. At the same time, PSA was undetectable. We felt that we had achieved a good response at this point and the continuation of therapy was not necessary.

You can see his hematological parameter that he maintained all his hematological parameter perfectly well. There were no noticeable hematologic toxicity. There was just mild decline in platelet level, but it never reached under 1000. These are his serial PSMA PET. First one is performed at the beginning, second at the mid-cycle, and third at the end of the cycle. You can see that at the mid-cycle there was a drop in tumor volume of 85% and at the end of the treatment there was 99.2% drop in PSMA tumor volume. Again, you can see that his PSA level had reached baseline and patient had not sustained any bone marrow toxicity. These are PSA values after he stopped therapy. Until this point, his PSA has remained undetectable.

These are individual slides showing the lesion-based analysis. So in the first pre-therapy scan you can see the lymph node in the left supraclavicular region, and that lymph node continues to decrease in size and it's barely seen on the CT images. On PET scan images, the intensity of uptake continues to decline. Same in the retrocrural region. At the beginning, the SUV in this lesion was 167. At the end of the therapy SUV was 3.7. The lymph node was barely noticeable.

Patient returned for his last follow-up exam on June 26th, 2023, and these are his follow-up labs, including PSA of less than 0.02. At this point, he feels well, his energy and hepatitis are well maintained, and continues to take Nubeqa and denies any other side effects. At this point there are no metabolic or hematologic toxicity and he continues to do well.

So, here is our one patient with excellent response to lutetium PSMA therapy and considering his very good response, we feel that factors that might have contributed to such a good response would be small tumor volume, he only has a lymph node metastases, no osseous or other visceral involvement, so the lymph node disease might be a reason for such good outcome, and his chemo naive status.

I would like to thank SNMMI Prostate Cancer Outreach Working Group for their help in putting this slide together. Thank you.