Safety of High-Dose Botulinum Toxin Injections for Parotid and Submandibular Gland Radioprotection

The effectiveness and safety of botulinum toxin treatment for sialorrhea due to severe brain injury

INTRODUCTION

Sialorrhea may be a consequence of severe acquired brain injury (ABI). Salivary gland botulinum neurotoxin (SG-BoNT) injections can reduce saliva production, but there is limited evidence for their use in ABI.We reviewed the effectiveness, impact on chest infection frequency, and safety of SG-BoNT for sialorrhea in a cohort of patients with severe ABI.

MATERIALS/METHODS

Retrospective cohort study of 49 patients, in a specialist ABI care facility, with sialorrhea who received SG-BoNT.Outcome measures included pre- and post-injection Drooling Severity and Frequency Scale (DSFS) scores, pre- and post-injection chest infection frequency, and adverse events.

RESULTS

Forty-nine patients received 79 SG-BoNT treatments (100 to 200 units of botulinum toxin A).Post-treatment the whole group showed significantly reduced mean DSFS scores (z = -6.4, p < 0.00001) and significantly fewer chest infections (z = -3.15, p = 0.0016). A reduction in chest infection frequency was seen in patients who received repeated treatments (2 or more) and/or higher SG-BoNT doses. There were no adverse events.

CONCLUSIONS

There is limited evidence for SG-BoNT in the treatment of sialorrhea for people with ABI but this treatment is clinically effective with no detectable adverse effects in this cohort. The reduction in chest infection frequency following repeated SG-BoNT injections is an important novel finding.

Evaluating Xerostomia as a side effect of [255Ac]Ac-PSMA therapy in prostate cancer: a systematic review and meta-analysis

PURPOSE

This systematic review and meta-analysis evaluates xerostomia occurrence in prostate cancer (PC) patients undergoing [225Ac]Ac-prostate-specific membrane antigen ([225Ac]Ac-PSMA) therapy.

METHODS

Following the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) guidelines, comprehensive electronic searches were conducted across PubMed, Scopus, and Web of Science. The study included articles addressing xerostomia as a side effect of [225Ac]Ac-PSMA therapy in clinical settings, encompassing both tandem and monotherapy strategies. Methodological quality was assessed using the National Institutes of Health (NIH) Assessment Tool. Stata software was employed to perform pooled xerostomia rates, heterogeneity analysis, meta-regression, and publication bias analysis.

RESULTS

Twenty studies met inclusion criteria, comprising 2949 [225Ac]Ac-PSMA cycles administered to 1207 PC patients. For [225Ac]Ac-PSMA monotherapy, the pooled rate of any-grade xerostomia was 84% (95%CI: 69-94%). Grade 1-2 xerostomia had a pooled rate 83% (95%CI: 71-93%), while therapy discontinuation due to xerostomia was 5% (95%CI: 0-13%). Grade 3 xerostomia was evident in 13% (95%CI: 7-20%). [225Ac]Ac/[177Lu]Lu-PSMA tandem therapy resulted in lower pooled rate of 68% for grade 1-2 toxicity (95%CI: 17-100%). Indirect comparison revealed a two-fold decrease in xerostomia risk with tandem protocol compared to monotherapy. Significant heterogeneity was observed, primarily influenced by baseline median prostate-specific antigen values (p = 0.04). Publication bias was present in most xerostomia subgroups, with trim-and-fill analysis adjusting for effect size in specific categories.

CONCLUSION

Xerostomia is most pronounced in patients undergoing [225Ac]Ac-PSMA monotherapy. Tandem approach with [177Lu]Lu-PSMA could reduce xerostomia rates and improve compliance. Further large-scale, prospective studies are necessary for generalization and result consolidation.

Long-Term Safety and Survival Outcomes of [225Ac]Ac-PSMA (Prostate-Specific Membrane Antigen) and [225Ac]Ac-/[177Lu]Lu-PSMA (TANDEM) Radioligand Therapy (PRLT) in Metastatic Castration-Resistant Prostate Cancer

This study aims to retrospectively assess the safety of [225Ac]Ac-PSMA-PRLT, both as monotherapy and in combination (TANDEM) with Lutetium-177, concerning tolerance after the radiopharmaceutical administration and long-term safety, its impact on salivary glands' function, overall survival (OS), and follow-up duration. Between December 2020 and September 2024, 89 patients received a total of 151 cycles of [225Ac]Ac-PSMA-PRLT. Patients with at least one follow-up (n = 71) were included in the analysis to evaluate xerostomia, as well as long-term hematological, renal, and hepatic toxicities, graded according to CTCAE v5.0. The most common adverse event after the radiopharmaceutical administration was flare pain (n = 16). As of the time of analysis, 68 patients had passed away (76.4%; range of survival 5 days to 39 months, median 7 months), while 21 patients were still alive (23.6%; follow-up duration: 1-33 months). Severe (G3/G4) long-term adverse events were rare, with 15 cases of G3 anemia (21.1%), 6 cases of G3 leukocytopenia (8.4%), and 14 cases of G3/G4 thrombocytopenia (19.7%). Hematological toxicity was primarily associated with severe bone marrow involvement or prior chemotherapy. Additionally, one case of G3 nephrotoxicity (1.4%) and six cases of G3 hepatotoxicity (8.4%) were observed. Only nine patients (12.7%) reported de novo xerostomia (G1/G2). In conclusion, this study demonstrates that [225Ac]Ac-PSMA PRLT, both as monotherapy and combined with [177Lu]Lu-PSMA as TANDEM PRLT, is generally safe in terms of both tolerance after the radiopharmaceutical administration and long-term toxicity.

The Esthetic Use of Botulinum Toxins in Cancer Patients: Providing a Foundation for Future Indications

Advances in oncological treatments have improved the survival rates of cancer patients but have often resulted in significant physical changes that negatively impact their self-esteem and psychological well-being. Cancer patients frequently ask esthetic practitioners to perform procedures to address such changes. However, practitioners often hesitate to satisfy such requests due to lacking guidelines or recommendations. The use of botulinum toxins (BoNTs) for esthetic purposes has shown significant promise in improving the quality of life for cancer patients. This review explores the broad application of BoNTs in many medical branches, focusing on oncology. A substantial amount of literature shows that BoNTs are safe and effective as a type of adjunctive therapy compared to classical cancer treatments. We provide our expert opinion that the use of BoNTs for esthetic purposes is safe for cancer patients and even recommended for those whose mood is influenced by the worsening of their physical appearance. Careful patient selection and interdisciplinary collaboration are essential to the safe integration of BoNTs into cancer care.

Salivary toxicity from PSMA-targeted radiopharmaceuticals: What we have learned and where we are going

Clinical trials of prostate-specific membrane antigen (PSMA) targeted radiopharmaceuticals have shown encouraging results. Some agents, like lutetium-177 [177Lu]Lu-PSMA-617 ([177Lu]Lu-PSMA-617), are already approved for late line treatment of metastatic castration-resistant prostate cancer (mCRPC). Projections are for continued growth of this treatment modality; [177Lu]Lu-PSMA-617 is being studied both in earlier stages of disease and in combination with other anti-cancer therapies. Further, the drug development pipeline is deep with variations of PSMA-targeting radionuclides, including higher energy alpha particles conjugated to PSMA-honing vectors. It is safe to assume that an increasing number of patients will be exposed to PSMA-targeted radiopharmaceuticals during the course of their cancer treatment. In this setting, it is important to better understand and mitigate the most commonly encountered toxicities. One particularly vexing side effect is xerostomia. In this review, we discuss the scope of the problem, inventories to better characterize and monitor this troublesome side effect, and approaches to preserve salivary function and effectively palliate symptoms. This article aims to serve as a useful reference for prescribers of PSMA-targeted radiopharmaceuticals, while also commenting on areas of missing data and opportunities for future research.

PSMA-Targeted Radiopharmaceuticals for Prostate Cancer Diagnosis and Therapy

ABSTRACT

Prostate cancer (PCa) is the most common noncutaneous malignancy in men. Until recent years, accurate imaging of men with newly diagnosed PCa, or recurrent or low-volume metastatic disease, was limited. Further, therapeutic options for men with advanced, metastatic, castration-resistant disease were increasingly limited as a result of increasing numbers of systemic therapies being combined in the upfront metastatic setting. The advent of urea-based, small-molecule inhibitors of prostate-specific membrane antigen (PSMA) has partially addressed those shortcomings in diagnosis and therapy of PCa. On the diagnostic side, there are multiple pivotal phase III trials with several different agents having demonstrated utility in the initial staging setting, with generally modest sensitivity but very high specificity for determining otherwise-occult pelvic nodal involvement. That latter statistic drives the utility of the scan by allowing imaging interpreters to read with very high sensitivity while maintaining a robust specificity. Other pivotal phase III trials have demonstrated high detection efficiency in patients with biochemical failure, with high positive predictive value at the lesion level, opening up possible new avenues of therapy such as metastasis-directed therapy. Beyond the diagnostic aspects of PSMA-targeted radiotracers, the same urea-based chemical scaffolds can be altered to deliver therapeutic isotopes to PCa cells that express PSMA. To date, one such agent, when combined with best standard-of-care therapy, has demonstrated an ability to improve overall survival, progression-free survival, and freedom from skeletal events relative to best standard-of-care therapy alone in men with metastatic, castration-resistant PCa who are post chemotherapy. Within the current milieu, there are a number of important future directions including the use of artificial intelligence to better leverage diagnostic findings, further medicinal chemistry refinements to the urea-based structure that may allow improved tumor targeting and decreased toxicities, and the incorporation of new radionuclides that may better balance efficacy with toxicities than those nuclides that are available.

Botulinum Toxin Treatment for Cancer-Related Disorders: A Systematic Review

This systematic review investigates the effect of botulinum neurotoxin (BoNT) therapy on cancer-related disorders. A major bulk of the literature is focused on BoNT's effect on pain at the site of surgery or radiation. All 13 published studies on this issue indicated reduction or cessation of pain at these sites after local injection of BoNTs. Twelve studies addressed the effect of BoNT injection into the pylorus (sphincter between the stomach and the first part of the gut) for the prevention of gastroparesis after local resection of esophageal cancer. In eight studies, BoNT injection was superior to no intervention; three studies found no difference between the two approaches. One study compared the result of intra-pyloric BoNT injection with preventive pyloromyotomy (resection of pyloric muscle fibers). Both approaches reduced gastroparesis, but the surgical approach had more serious side effects. BoNT injection was superior to saline injection in the prevention of esophageal stricture after surgery (34% versus 6%, respectively, p = 0.02) and produced better results (30% versus 40% stricture) compared to steroid (triamcinolone) injection close to the surgical region. All 12 reported studies on the effect of BoNT injection into the parotid region for the reduction in facial sweating during eating (gustatory hyperhidrosis) found that BoNT injections stopped or significantly reduced facial sweating that developed after parotid gland surgery. Six studies showed that BoNT injection into the parotid region prevented the development of or healed the fistulas that developed after parotid gland resection-parotidectomy gustatory hyperhidrosis (Frey syndrome), post-surgical parotid fistula, and sialocele. Eight studies suggested that BoNT injection into masseter muscle reduced or stopped severe jaw pain after the first bite (first bite syndrome) that may develop as a complication of parotidectomy.

Botox for the prevention of radiation-induced Sialadenitis and xerostomia in head and neck cancer patients: A pilot study

BACKGROUND

To determine the safety of Botox and its potential effect on alleviating radiation therapy (RT)-induced sialadenitis in head and neck cancer patients.

METHODS

Twenty patients with stage III/IV head and neck cancer were randomized to receive Botox or saline injections into both submandibular glands (SMG). There were three visits: one before RT (V1); 1 week after RT (V2); and 6 weeks after RT (V3), each of which included saliva collection, a 24-h dietary recall, and a quality-of-life survey.

RESULTS

No adverse events were observed. While the control group was much older, the Botox group more commonly underwent induction chemotherapy compared with controls. From V1 to V2, salivary flow decreased in both groups, but only in the control group from V1 to V3. CXCL-1 (GRO), a neutrophil chemoattractant, was lower in the Botox group compared with the control group at V3.

CONCLUSION

Botox can be safely administered to the salivary glands prior to external beam radiation without observed complications or side-effects. After an initial reduction in salivary flow following RT, the Botox group showed lack of further flow reduction compared with controls. The inflammatory marker CXCL 1, which was reduced in the in Botox group at V3, may be a candidate for further studies of radiation-induced sialadenitis.

Introduction to the Toxins Special Issue on Botulinum Toxins: New Uses in the Treatment of Diseases

Studies on animals and humans have amply demonstrated the therapeutic efficacy of botulinum neurotoxins (BoNTs) in many pathologies [...].

The Potential Role of Spa Therapy in Managing Frailty in Rheumatic Patients: A Scoping Review

Frailty is not limited to the elderly, as patients with rheumatic diseases can also experience this condition. The present scoping review aimed to investigate the possibility of using the health resort setting as an alternative location for managing rheumatic patients with frailty. The research resulted in finding several in vitro, in vivo, and clinical studies, resulting in evidence supporting the effectiveness of spa treatments in reducing pain, improving function, and managing comorbidity in rheumatic diseases. Additionally, spa treatments were demonstrated to modulate the MAPK/ERK pathway and the NF-kB pathway's activation and to reduce proinflammatory molecules' secretion in rheumatic diseases, thus suggesting their potential effective role in the regulation of inflammaging in frailty. Moreover, the health resort setting may offer potential resources to reduce risk factors, such as drug consumption, inactivity, and disease severity, and may serve as a setting for developing prevention protocols for frailty. Future research should explore innovative approaches, such as exercise training and early diagnostics, for the overall management of frailty in rheumatic patients in the spa setting.

Efficacy of Intra-Articular Injection of Botulinum Toxin Type A (IncobotulinumtoxinA) in Temporomandibular Joint Osteoarthritis: A Three-Arm Controlled Trial in Rats

Temporomandibular disorders (TMD) are complex pathologies responsible for chronic orofacial pain. Intramuscular injection of botulinum toxin A (BoNT/A) has shown effectiveness in knee and shoulder osteoarthritis, as well as in some TMDs such as masticatory myofascial pain, but its use remains controversial. This study aimed to evaluate the effect of intra-articular BoNT/A injection in an animal model of temporomandibular joint osteoarthritis. A rat model of temporomandibular osteoarthritis was used to compare the effects of intra-articular injection of BoNT/A, placebo (saline), and hyaluronic acid (HA). Efficacy was compared by pain assessment (head withdrawal test), histological analysis, and imaging performed in each group at different time points until day 30. Compared with the rats receiving placebo, those receiving intra-articular BoNT/A and HA had a significant decrease in pain at day 14. The analgesic effect of BoNT/A was evident as early as day 7, and lasted until day 21. Histological and radiographic analyses showed decrease in joint inflammation in the BoNT/A and HA groups. The osteoarthritis histological score at day 30 was significantly lower in the BoNT/A group than in the other two groups (p = 0.016). Intra-articular injection of BoNT/A appeared to reduce pain and inflammation in experimentally induced temporomandibular osteoarthritis in rats.

Drug Therapeutics Delivery to the Salivary Glands: Intraglandular and Intraductal Injections

Salivary gland hypofunction and xerostomia following pathological conditions like Sjogren's syndrome or head and neck radiotherapy usually lead to tremendous impairment of oral health, speech, and swallowing. The use of systemic drugs to alleviate the symptoms of these conditions has been associated with various adverse effects. Techniques of local drug delivery to the salivary gland have grown enormously to address this problem properly. The techniques include intraglandular and intraductal injections. In this chapter, we will provide a review of the literature for both techniques while incorporating our lab experience in using them.

Diagnosis, Prevention, and Treatment of Radiotherapy-Induced Xerostomia: A Review

In patients with head and neck cancer, irradiation (IR)-sensitive salivary gland (SG) tissue is highly prone to damage during radiotherapy (RT). This leads to SG hypofunction and xerostomia. Xerostomia is defined as the subjective complaint of dry mouth, which can cause other symptoms and adversely affect the quality of life. In recent years, diagnostic techniques have constantly improved with the emergence of more reliable and valid questionnaires as well as more accurate equipment for saliva flow rate measurement and imaging methods. Preventive measures such as the antioxidant MitoTEMPO, botulinum toxin (BoNT), and growth factors have been successfully applied in animal experiments, resulting in positive outcomes. Interventions, such as the new delivery methods of pilocarpine, edible saliva substitutes, acupuncture and electrical stimulation, gene transfer, and stem cell transplantation, have shown potential to alleviate or restore xerostomia in patients. The review summarizes the existing and new diagnostic methods for xerostomia, along with current and potential strategies for reducing IR-induced damage to SG function. We also aim to provide guidance on the advantages and disadvantages of the diagnostic methods. Additionally, most prevention and treatment methods remain in the stage of animal experiments, suggesting a need for further clinical research, among which we believe that antioxidants, gene transfer, and stem cell transplantation have broad prospects.

Salivary Gland Toxicity of PSMA-Targeted Radioligand Therapy with 177Lu-PSMA and Combined 225Ac- and 177Lu-Labeled PSMA Ligands (TANDEM-PRLT) in Advanced Prostate Cancer: A Single-Center Systematic Investigation

Purpose: PSMA-targeted radioligand therapy (PRLT) is a promising treatment option for patients with metastatic castration-resistant prostate cancer (mCRPC). However, a high uptake of the radiopharmaceutical in the salivary glands (SG) can lead to xerostomia and becomes dose-limiting for 225Ac-PSMA-617. This study investigated the sialotoxicity of 177Lu-PSMA-I&T/-617 monotherapy and co-administered 225Ac-PSMA-617 and 177Lu-PSMA-617 (Tandem-PPRLT). Methods: Three patient cohorts, that had undergone 177Lu-PSMA-I&T/-617 monotherapy or Tandem-PRLT, were retrospectively analyzed. In a short-term cohort (91 patients), a xerostomia assessment (CTCAE v.5.0), a standardized questionnaire (sXI), salivary gland scintigraphy (SGS), and SG SUVmax and the metabolic volume (MV) on 68Ga-PSMA-11-PET/CT were obtained before and after two cycles of 177Lu-PSMA-I&T/-617. In a long-term cohort, 40 patients were similarly examined. In a Tandem cohort, the same protocol was applied to 18 patients after one cycle of Tandem-PRLT. Results: Grade 1 xerostomia in the short-term follow-up was observed in 22 (24.2%) patients with a worsening of sXI from 7 to 8 at (p < 0.05). In the long-term cohort, xerostomia grades 1 to 2 occurred in 16 (40%) patients. SGS showed no significant changes, but there was a decline of the MV of all SGs. After Tandem-PRLT, 12/18 (66.7%) patients reported xerostomia grades 1 to 2, and the sXI significantly worsened from 9.5 to 14.0 (p = 0.005), with a significant reduction in the excretion fraction (EF) and MV of all SGs. Conclusion: 177Lu-PSMA-I&T/-617 causes only minor SG toxicity, while one cycle of Tandem-PRLT results in a significant SG impairment. This standardized protocol may help to objectify and quantify SG dysfunction.

Advances in PSMA theranostics

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PSMA is an appealing target for theranostic because it is a transmembrane protein with a known substrate that is overexpessed on prostate cancer cells and internalizes upon ligand binding.

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There are a number of PSMA theranostic ligands in clinical evaluation, clinical trial, or clinically approved.

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PSMA theranostic ligands increase progression-free survival, overall survival, and pain in patients with metastatic castration resistant prostate cancer.

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A major obstacle to PSMA-targeted radioligand therapy is off-target toxicity in salivary glands.

The validation of prostate specific membrane antigen (PSMA) as a molecular target in metastatic castration-resistant prostate cancer has stimulated the development of multiple classes of theranostic ligands that specifically target PSMA. Theranostic ligands are used to image disease or selectively deliver cytotoxic radioactivity to cells expressing PSMA according to the radioisotope conjugated to the ligand. PSMA theranostics is a rapidly advancing field that is now integrating into clinical management of prostate cancer patients. In this review we summarize published research describing the biological role(s) and activity of PSMA, highlight the most clinically advanced PSMA targeting molecules and biomacromolecules, and identify next generation PSMA ligands that aim to further improve treatment efficacy. The goal of this review is to provide a comprehensive assessment of the current state-of-play and a roadmap to achieving further advances in PSMA theranostics.