Hyaluronic Acid Spacer for Hypofractionated Prostate Radiation Therapy: A Randomized Clinical Trial.

Importance: Hypofractionated radiation therapy (RT) for prostate cancer has been associated with greater acute grade 2 gastrointestinal (GI) toxic effects compared with conventionally fractionated RT. Objective: To evaluate whether a hyaluronic acid rectal spacer could (1) improve rectal dosimetry and (2) affect acute grade 2 or higher GI toxic effects for hypofractionated RT. Design, Setting, and Participants: This randomized clinical trial was conducted from March 2020 to June 2021 among 12 centers within the US, Australia, and Spain, with a 6-month follow-up. Adult patients with biopsy-proven, T1 to T2 prostate cancer with a Gleason score 7 or less and prostate-specific antigen level of 20 ng/mL or less (to convert to µg/L, multiply by 1) were blinded to the treatment arms. Of the 260 consented patients, 201 patients (77.3%) were randomized (2:1) to the presence or absence of the spacer. Patients were stratified by intended 4-month androgen deprivation therapy use and erectile quality. Main Outcomes and Measures: For the primary outcome, we hypothesized that more than 70% of patients in the spacer group would achieve a 25% or greater reduction in the rectal volume receiving 54 Gy (V54). For the secondary outcome, we hypothesized that the spacer group would have noninferior acute (within 3 months) grade 2 or higher GI toxic effects compared with the control group, with a margin of 10%. Results: Of the 201 randomized patients, 8 (4.0%) were Asian, 26 (12.9%) Black, 42 (20.9%) Hispanic or Latino, and 153 (76.1%) White; the mean (SD) age for the spacer group was 68.6 (7.2) years and 68.4 (7.3) years for the control group. For the primary outcome, 131 of 133 (98.5%; 95% CI, 94.7%-99.8%) patients in the spacer group experienced a 25% or greater reduction in rectum V54, which was greater than the minimally acceptable 70% (P < .001). The mean (SD) reduction was 85.0% (20.9%). For the secondary outcome, 4 of 136 patients (2.9%) in the spacer group and 9 of 65 patients (13.8%) in the control group experienced acute grade 2 or higher GI toxic effects (difference, -10.9%; 95% 1-sided upper confidence limit, -3.5; P = .01). Conclusions and Relevance: The trial results suggest that rectal spacing with hyaluronic acid improved rectal dosimetry and reduced acute grade 2 or higher GI toxic effects. Rectal spacing should potentially be considered for minimizing the risk of acute grade 2 or higher toxic effects for hypofractionated RT. Trial Registration: ClinicalTrials.gov Identifier: NCT04189913.

Open Label Phase II Study of Enzalutamide With Concurrent Administration of Radium 223 Dichloride in Patients With Castration-Resistant Prostate Cancer.

BACKGROUND: Numerous globally approved castration-resistant prostate cancer (CRPC) therapies are available. Enzalutamide and radium 223 (Ra 223) are approved for survival prolongation and ability to delay radiographic progression. Both have markedly different mechanisms of action as well as safety and tolerability profiles. We prospectively investigated their combined safety and tolerability. PATIENTS AND METHODS: EnzaRadiCate, a phase II investigator-initiated trial, enrolled subjects with metastatic CRPC from 4 United States uro-oncology research sites. Safety assessment included physical examination, Eastern Cooperative Oncology Group status, electrocardiogram results, laboratory values, opioid use, radiographic responses, and adverse events (AEs). Quality of life and pain were assessed using the Functional Assessment of Cancer Therapy-Prostate (FACT-P) and the Brief Pain Inventory Short Form (BPI-SF) questionnaires. RESULTS: Thirty-nine subjects completed at least 2 cycles of Ra 223, and 34 (87%) completed all 6 cycles through and the EOT visit. Sixty-one treatment-related AEs were reported by 53.8% of subjects. The most frequent AEs were fatigue (25.6%), nausea (17.9%), and anemia (12.8%). Three subjects experienced non-treatment-related serious AEs. One subject was hospitalized for sepsis, and 2 deaths were attributed to disease progression. Fifteen (38.5%) subjects demonstrated radiographic progression, and 24 (61.5%) subjects had no radiographic progression. CONCLUSIONS: Safety and tolerability of combinatorial use of enzalutamide and Ra 223 were demonstrated. Subjects experienced improvements in quality of life and pain, without unexpected toxicities nor increases in falls, fractures, or deaths. Phase III combination trials of Ra 223 with novel oral hormonal agents are ongoing to further evaluate radiographic progression and overall survival benefit.

eRADicAte: A Prospective Evaluation Combining Radium-223 Dichloride and Abiraterone Acetate Plus Prednisone in Patients With Castration-Resistant Prostate Cancer.

BACKGROUND: Multiple castration-resistant prostate cancer (CRPC) therapies are approved by the United States Food and Drug Administration. Radium-223 dichloride (Ra-223) with abiraterone acetate plus prednisone have different mechanisms of action and distinct off-target side-effect profiles. We prospectively investigated their combined safety, tolerability, and patient-reported outcome measures. PATIENTS AND METHODS: eRADicAte, an investigator-initiated, phase II trial, studied 31 patients with metastatic CRPC, from 5 United States uro-oncology research sites. Patients completed 6 cycles of Ra-223 with concurrent abiraterone therapy. Quality of life and pain were assessed using the Functional Assessment of Cancer Therapy-Prostate and the Brief Pain Inventory-Short Form questionnaires and their subscales; we reported the number of subjects meeting standardized criteria for clinically meaningful improvements on each scale. Safety assessment included Eastern Cooperative Oncology Group performance status, laboratory changes, opioid use, radiographic responses, and adverse events (AEs). RESULTS: Twenty of 31 (65%) experienced positive clinically meaningful improvement changes on the Functional Assessment of Cancer Therapy-Prostate, and 25 (81%) of 31 on the Prostate Cancer Subscale. Eighteen (58%) of 31 demonstrated reduced pain intensity and 12 (39%) of 31 demonstrated reduction of pain interference in their lives. At baseline, subjects averaged 11.6 ± 2.8 bone lesions; at the end of treatment, subjects averaged 5.6 ± 2.4 bone lesions (P = .0002). The most frequent AEs were diarrhea (17%), nausea (17%), and fatigue (14%). There were 6 serious AEs; 1 led to study withdrawal. CONCLUSIONS: Patients experienced clinically meaningful improvements in quality of life and pain, without unexpected adverse toxicities. Phase III combination trials of Ra-223 with novel oral hormonal agents are ongoing to further evaluate radiographic progression and overall survival benefit.