Data Demonstrate Safety of Sculptable Hyaluronic Acid Rectal Spacer in Patients Undergoing Prostate Cancer Treatment

Data presented in 3 abstracts at the American Society for Radiation Oncology (ASTRO) 2024 Annual Meeting, which took place in Washington, DC, last month support the safety and efficacy of a hyaluronic acid rectal spacer. It is designed to significantly reduce radiation that reaches the rectum during prostate cancer radiation therapy.

The first abstract reviewed retrospective data from 100 men in Australia who were undergoing moderately fractionated external beam radiation therapy (EBRT; 60Gy/62Gy in 20 fractions) for localized prostate cancer using the Barrigel rectal spacer.¹ Researchers assessed implants for quality (medical stability quick screen, or mSQS score), symmetry (Fisher-Valuck, or FV score), and rectal wall infiltration (RWI), as well as acute and late gastrointestinal (GI) toxicity. Excellent implant quality (mSQS score=1) was reported for 74 patients; 24 patients had a score of 2, and only 2 patients had a 0 score. Symmetrical rectal spacing (FV score=1) was achieved in 97% of implants. The Barrigel rectal spacer was reported as very easy (98%) or easy (2%) to implant by physicians. No acute or late GI toxicity >grade 2 was reported; 7 acute and 5 late grade 1 toxicity events were reported. RWI occurred in 1 patient and was reversed with hyaluronidase with no subsequent adverse effects. Only 1 case of regional prostate cancer recurrence has been reported with a median follow-up of 1.68 years.

The second abstract reviewed data from a retrospective analysis of inadvertent RWI in 5000 Australian men receiving Barrigel rectal spacer for prostate cancer radiation therapy.² Results of magnetic resonance imaging were used to identify RWI. Patients with RWI were followed for the remainder of their radiation therapy and for an additional 3 months following completion of radiation therapy. The study identified 16 patients with RWI after Barrigel rectal spacer insertion (grade 1 by FV criteria, n=5; grade 2, n=6; grade 3, n=5), with a median volume of misplaced Barrigel rectal spacer of 2.8 cc (total average Barrigel rectal spacer volume was 9.2 cc). No post-procedural GI symptoms or acute grade 2+ GI toxicity was reported among these 16 men, and the rectal mucosa was intact in the 12 men who underwent sigmoidoscopy. Seven of the 16 men underwent Barrigel rectal spacer reversal procedures with hyaluronidase, all of which were successful, and no post-reversal complications were reported. The other 9 men were monitored. No severe adverse complications (mucosal ulceration, pelvic abscess, recto-prostatic fistula) have been reported among the 16 men with RWI. The presence of RWI resulted in delayed initiation of radiation therapy in 11 men (median delay = 3.2 months).²

The third abstract discussed Barrigel rectal spacer safety, rectal separation, ease of spacer placement, and treatment toxicity in 17 men undergoing repeat local radiation therapy for prostate cancer using stereotactic body radiotherapy.³ Researchers in that study noted a 100% success rate for Barrigel rectal spacer placement, with no use of saline dissection and no adverse events reported. Mean minimum separation between gross tumor volume and rectal tissue was 8.7 (±5.6) mm, and adequate separation was achieved in 86.4% of cases. No grade 1 GI toxicity or acute grade 3+ urinary toxicity was reported; there was 1 case of grade 3 hemorrhagic cystitis (which the patient also experienced during initial EBRT). Maximum point dose (D_max) for radiation was 22.7 Gy (±6.8), and the dose received by 30% (D30) and 60% (D60) of the prostate was 6.8 Gy (±3.0), and 3.0 Gy (±2.2), respectively.

Michael Chao, MD, a radiation oncologist at the Olivia Newton John Cancer Wellness & Research Centre in Victoria, Australia, and author of 2 abstracts said in a press release about the findings, that “They also show that the incidence of RWI with Barrigel rectal spacer is quite rare—only 0.32%—and that these rare cases can be reversed effectively with hyaluronidase. Reversal is not feasible when RWI occurs with other spacers because the inorganic materials of which they are made cannot safely be dissolved in the body and must be absorbed over time. This is another important benefit of Barrigel rectal spacer that should be considered when selecting a rectal spacer for men undergoing prostate cancer radiation therapy.”⁴

References

1. Lin YH, Lim Joon D, Bolton D, et al. Impact of hyaluronic acid (HA) rectal spacer quality score (SQS) and Fischer-Valuck (FV) spacer symmetry score on rectal dosimetry and acute and late gastrointestinal (GI) toxicity outcomes—an Australian experience. Abstract presented at: ASTRO 2024 Annual Meeting; September 29-October 2, 2024; Washington, DC. Abstract 3222.
2. Hong A, Bolton D, Ramani S, et al. Rectal wall infiltration (RWI) with hyaluronic acid based rectal spacer reversal protocol. Abstract presented at: ASTRO 2024 Annual Meeting; September 29-October 2, 2024; Washington, DC. Abstract 3185.
3. McLean LN, Nair N, Poiset SJ, et al. Hyaluronic acid rectal spacer in locally recurrent prostate cancer with prior radiation receiving SBRT: on feasibility, safety, and toxicity. Abstract presented at: ASTRO 2024 Annual Meeting; September 29-October 2, 2024; Washington, DC. Abstract 3236.
4. New data presented at ASTRO 2024 further demonstrate the safety and efficacy of Barrigel rectal spacer, the first and only sculptable hyaluronic acid rectal spacer, in patients undergoing radiation therapy for prostate cancer. Press release. Teleflex. Published October 2, 2024. Accessed October 18, 2024. https://investors.teleflex.com/news/news-details/2024/New-Data-Presented-at-ASTRO-2024-Further-Demonstrate-the-Safety-and-Efficacy-of-Barrigel-Rectal-Spacer-the-First-and-Only-Sculptable-Hyaluronic-Acid-Rectal-Spacer-in-Patients-Undergoing-Radiation-Therapy-for-Prostate-Cancer1-3/default.aspx