Incorporating radioligand therapy in clinical practice in the United States for patients with prostate cancer

Prostate cancer (PC) is the second most commonly diagnosed cancer in the United States. Advanced PC evolves to metastatic castration-resistant PC (mCRPC). Theranostics combining prostate-specific membrane antigen-targeted positron emission tomography imaging and radioligand therapy (RLT) represents a precision medicine approach to PC treatment. With the recent approval of lutetium Lu 177 (¹⁷⁷Lu) vipivotide tetraxetan for men with mCRPC, the utilization of RLT will increase. In this review, we suggest a framework for incorporating RLT for PC into clinical practice. A search of PubMed and Google Scholar was performed using keywords related to PC, RLT, prostate-specific membrane antigen, and novel RLT centers. The authors also provided opinions based on their clinical experience. The setup and operation of an RLT center requires the diligence and cooperation of a well-trained multidisciplinary team committed to patient safety and clinical efficacy. Administrative systems should ensure that treatment scheduling, reimbursement, and patient monitoring are efficient. For optimal outcomes, the clinical care team must have an organizational plan that delineates the full range of required tasks. Establishing new RLT centers for treatment of PC is possible with appropriate multidisciplinary planning. We provide an overview of the key elements to consider when establishing a safe, efficient, and high-quality RLT center.

Primary radiotherapy for localized orbital MALT lymphoma

PURPOSE

To define the natural history, prognosis, and radiocurability of localized orbital extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT).

METHODS AND MATERIALS

Clinical records and pathologic material of 40 patients treated with local radiotherapy for localized orbital lymphoma were reviewed. Treatment consisted of 30-40 Gy in 1.8-2-Gy fractions (mean 34 Gy) of irradiation using 9-20-MeV electrons for conjunctival lesions, or 6-MV photons with complex treatment planning for retrobulbar lesions. The lens was routinely shielded with the use of a suspended eye bar.

RESULTS

Upon pathologic review, 31 cases of orbital MALT lymphoma were identified. With the median follow-up of 5.9 years (range 9 months-0.3 years), the actuarial 10-year overall survival was 73%. Local control was 100%. Five distant failures resulted in a projected 10-year freedom from relapse of 71%. Most of the failures were extranodal in sites where MALT lymphoma has previously been shown to arise. No difference in outcome was observed among patients treated to less than or equal to 34 Gy vs. those treated to higher radiation doses. Two patients experienced clinically significant retinal damage after doses > or = Gy.

CONCLUSION

In this study, localized orbital MALT lymphoma was well controlled with radiotherapy. Even following relapse, patients with orbital MALT lymphoma exhibited an indolent course. Relapse occurred predominantly in extranodal mucosal sites, implying a possible homing mechanism for MALT lymphoma cells. Given the excellent local control rates, our current treatment recommendation is to use a radiation dose of 30-30.6 Gy in 1.5-.8-Gy fractions to minimize risk of late toxicity.

Stereotactic radiosurgical boost following radiotherapy in primary nasopharyngeal carcinoma: impact on local control

PURPOSE

Treatment of patients with nasopharyngeal carcinoma using external beam radiation therapy (EBRT) alone results in significant local recurrence. Although intracavitary brachytherapy can be used as a component of management, it may be inadequate if there is extension of disease to the skull base. To improve local control, stereotactic radiosurgery was used to boost the primary tumor site following fractionated radiotherapy in patients with nasopharyngeal carcinoma.

METHODS AND MATERIALS

Twenty-three consecutive patients were treated with radiosurgery following radiotherapy for nasopharyngeal carcinoma from 10/92 to 5/98. All patients had biopsy confirmation of disease prior to radiation therapy; Stage III disease (1 patient), Stage IV disease (22 patients). Fifteen patients received cisplatinum-based chemotherapy in addition to radiotherapy. Radiosurgery was delivered using a frame-based LINAC as a boost (range 7 to 15 Gy, median 12 Gy) following fractionated radiation therapy (range 64.8 to 70 Gy, median 66 Gy).

RESULTS

All 23 patients (100%) receiving radiosurgery as a boost following fractionated radiation therapy are locally controlled at a mean follow-up of 21 months (range 2 to 64 months). There have been no complications of treatment caused by radiosurgery. However, eight patients (35%) have subsequently developed regional or distant metastases.

CONCLUSIONS

Stereotactic radiosurgical boost following fractionated EBRT provides excellent local control in advanced stage nasopharynx cancer and should be considered for all patients with this disease. The treatment is safe and effective and may be combined with cisplatinum-based chemotherapy.

Effect of combined transient androgen deprivation and irradiation following radical prostatectomy for prostatic cancer

PURPOSE

To evaluate whether transient androgen deprivation improves outcome in patients irradiated after radical prostatectomy for locally advanced disease, persistent or rising postoperative prostate specific antigen (PSA), or local recurrence.

METHODS AND MATERIALS

Records of 105 consecutive patients who were treated with pelvic irradiation after radical retropubic prostatectomy between August 1985 and December 1995 were reviewed. Seventy-four patients received radiation alone (mean follow up: 4.6 years), and 31 received transient androgen blockade with a gonadotropin-releasing hormone agonist (4) androgen receptor blocker (1) or both (24) beginning 2 months prior to irradiation (mean follow-up 3.0 years) for a mean duration of 6 months. Two of these patients were excluded from further analysis because they received hormonal therapy for more than 1 year. Patients received a prostatic fossa dose of 60-70 Gy at 2 Gy per fraction; 48 patients also received pelvic nodal irradiation to a median dose of 50 Gy. Survival, freedom from clinical relapse (FFCR), and freedom from biochemical relapse (FFBR) were evaluated by the Kaplan-Meier method. Biochemical relapse was defined as two consecutive PSA measurements exceeding 0.07 ng/ml.

RESULTS

At 5 years after irradiation, actuarial survival for all patients was 92%, FFCR was 77%, and FFBR was 34%. FFBR was significantly better among patients who received transient androgen blockade before and during radiotherapy than among those treated with radiation alone (56 vs. 27% at 5 years, p = 0.004). FFCR was also superior for the combined treatment group (100 vs. 70% at 5 years, p = 0.014). Potential clinical prognostic factors before irradiation did not differ significantly between treatment groups, including tumor stage, summed Gleason histologic score, lymph node status, indication for treatment, and PSA levels before surgery or subsequent treatment. Multivariate analysis revealed that transient androgen deprivation was the only significant predictor for biochemical failure.

CONCLUSION

This retrospective study of irradiation after radical prostatectomy suggests that transient androgen blockade and irradiation may improve freedom from early biochemical and clinically evident relapse compared to radiotherapy alone, although more prolonged follow-up will be needed to assess durability of impact upon clinical recurrence and survival rates.

Combinations of hormones and local therapies in locally advanced prostate carcinoma

Locally advanced adenocarcinoma of the prostate (American Urological Association stages B2, C; American Joint Committee on Cancer stages T2c, T3) has been difficult to control by either external-beam irradiation or radical prostatectomy. The combination of local therapies with hormonal manipulation is an innovative strategy to combat this entity. Hormonal regimens have evolved to include total androgen suppression, or maximal androgen blockade. In phase III trials, it appears that the combination of irradiation and hormones is superior to the use of radiotherapy alone. Results of phase III trials comparing surgery to combinations of surgery and hormones have been less encouraging. To date, no prospective randomized trial comparing the combination of hormones plus surgery to hormones plus irradiation has been completed.