Evaluation of off-label rapamycin use on oral health

Abstract

Rapamycin (sirolimus) is an FDA approved drug with immune modulating properties that is being prescribed off-label in adults as a preventative therapy to maintain healthspan. We recently published one of the first reports on 333 adults with a history of off-label rapamycin use. Along with presenting evidence that rapamycin can be used safely in adults of normal health status, we discovered that about 26% of rapamycin users also reported oral health changes. Given the recent evidence highlighting the potential benefits of rapamycin and its derivatives in enhancing oral health, we conducted a secondary data analysis to profile the oral health of off-label rapamycin users, the true incidence of mouth sores, and present specific case studies of periodontal bone loss quantification using an FDA-approved artificial intelligence platform. Contrary to expected findings and previous literature, dimensions of rapamycin usage (such as length of use, dosage, and interval) were not found to be related to the incidence of mouth ulcers in rapamycin users. Notably, among rapamycin users, the most deleterious forms of ulcers were found to be infrequent and not statistically linked to rapamycin usage, with most rapamycin users having a common transient form of mouth ulcers. Additionally, we describe the general oral health outcomes of off-label rapamycin users and provide recommendations for individuals engaging in off-label rapamycin to be regularly checked by a dentist or an oral health care provider. This report was limited by being a secondary data analysis taken from survey data that focused on a more holistic health model. Future studies will use a focused survey that collects data on more dimensions of oral health outcomes while including questions on oral health for non-rapamycin-using participants.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11357-024-01221-0.

Introduction

Geroscience is a burgeoning field that aims to decipher the underlying mechanisms of the aging process and its relationship with age-related functional decline and diseases [1–4]. The field aims to understand shared pathways that drive biological aging to ultimately target aging itself to delay or prevent multiple age-related disorders. Among the identified pathways, the inhibition of the mechanistic target of rapamycin (mTOR) pathway is one of the most robust and reproducible approaches to extend lifespan and promote healthspan in animal models [5–12]. Initial evidence supports that rapamycin or rapamycin derivatives may have similar beneficial effects on improving heart function in aged companion dogs [9], improving periodontal disease in aged rodents [11] and renal transplant patients [13], and restoring immune function in older adults [14, 15]. Recently, the off-label use of rapamycin has garnered interest due to its effects on potential longevity and health span improvement in preclinical studies [16, 17]. The term “off-label” refers to the legal use of approved prescription medication for an indication different from its approved indication. For example, a licensed healthcare provider in the United States can prescribe current Food and Drug Administration (FDA)–approved medications “off-label” when deemed appropriate by healthcare providers based on clinical judgment and scientific evidence.

Rapamycin (sirolimus, Rapamune) is FDA-approved for kidney transplant rejection, use in cardiac stents, and treatment in patients with lymphangioleiomyomatosis. Standard dosing involves a loading dose of up to 15 mg, followed by a maintenance dose of up to 10 mg daily. Despite its classification as an immunosuppressant at these doses, studies indicate that rapamycin and its derivatives (rapalogs) at varying doses and schedules may have other effects, such as improving immune function [14, 15] and reduced side effects [18]. However, safety concerns regarding the off-label use of rapamycin persist within the clinical and regulatory community.

To gather real-world data on individuals using rapamycin off-label for healthspan benefits, we recently published one of the first reports on 333 participants taking rapamycin off-label [19]. Along with documenting positive user experiences, our findings revealed that approximately 26% of rapamycin users reported oral health changes. Given recent evidence highlighting the potential benefits of rapamycin and its derivatives in enhancing oral health in animal models [11, 20–23] and transplant patients [13], our current study delves into the oral health profile of off-label rapamycin users through secondary data analysis. Specifically, we evaluate the true incidence of mouth sores—a term encompassing various conditions like stomatitis, mucositis, canker sores, or mTOR-inhibitor-associated stomatitis (mIAS)—alongside its correlation with the concentration and frequency of off-label rapamycin use. Additionally, we conduct an analysis of dental x-rays utilizing an FDA-approved artificial intelligence (AI) platform to evaluate the impact of off-label rapamycin use on periodontal bone loss.

Methods

Survey

The study is a secondary data-analysis of previously collected survey data regarding participants who used off-label rapamycin to improve their health span [19]. The original study used convenience sampling from those who met the appropriate criteria via physician recommendation, social media posts, word of mouth, and advertisement in rapamycin related groups. The initial data collection occurred between March 1, 2022, and June 30, 2022. The data used included demographic, rapamycin use history, recent health history, medical health, and oral health modules. The study was approved by the University of Washington Institutional Review Board (STUDY00014726).

Statistical analysis

The survey collected complete data on all rapamycin users and partial data on non-rapamycin users. As such, data pertaining to ulcers and medications are missing for non-rapamycin users. Therefore, many of the analyses pertained solely to rapamycin users, though any analyses with the appropriate data collected for non-users were conducted when applicable. The total number of participants in the study was n = 505 where 333 of the participants were rapamycin users, and 172 participants were non-rapamycin users. Analysis of the data involving rapamycin users was further adjusted to include only those who had been taking rapamycin for over 90 days at the time of the survey. In addition to using exclusionary criteria for participants with incomplete survey data, this left the final rapamycin user group at n = 245.

Outcomes were probed against demographic data to ensure no relation existed between variables of interest and miscellaneous factors such as age, weight, or sex, with analyses being either chi-square tests, Fisher’s exact tests, or logistic regression depending on whether the data was categorical or continuous. Logistic regression models were then used for the remaining variables of interest.

Three of the primary variables of interest (length of time on rapamycin, rapamycin dosage, and rapamycin use interval) were analyzed as both continuous variables and stratified categorical variables with stratification criteria based on quartile spread of data to ensure that each stratum contained roughly the same number of participants as the others. Participants with missing data were excluded from the analyses.

Dental case studies

Dental records release was completed by survey participants, which enabled the transfer of participant’s dental radiographs (x-rays) for analysis. The collected dental x-rays were compared longitudinally with the participant’s reported date of starting the rapamycin regimen. Three specific case studies are presented. To analyze periodontal bone loss, the dental x-rays were analyzed by Overjet, an FDA-approved AI Platform for bone level quantification. To compare radiographs taken before and after rapamycin use, radiographs with similar fields of view and the same teeth were analyzed by averaging the bone level quantification per tooth.

Results

Demographic data

The age, weight, and sex demographics of the eligible rapamycin users and non-rapamycin users are shown in Table 1. There are more men using rapamycin, with 80%, than non-users, with 63.4%, which also indicates a general male-skewed sex difference in the population between rapamycin users and non-users. The average age of rapamycin users is 8.4 years older than their non-users, with similar male (62.1 years) and female age (60.9 years) averages between rapamycin users and a larger age difference between males (51.8 years, p < 0.0001) and females (56.4 years) in the non-rapamycin users. In the context of weight, both male and female rapamycin users weighed less than non-rapamycin male (177 lbs. vs. 180 lbs.) and females (139.1 lbs. vs. 143 lbs.), but difference was not statistically significant. Most rapamycin users consisted of white participants between 89.0 and 91.3% (Table 2). Though there is a minor disparity between other ethnicities between the 90-day rapamycin group and non-users, the difference is 2.3%.

Table 1.

Age and weight of rapamycin users and non-users. Values shown are the mean, standard deviation, minimum, and maximum threshold for the age and weight of the survey respondents

Table 2.

Demographics of rapamycin users and non-users. The participants that elected to identify their race/ethnicity are further separated by users on rapamycin for more than 90 days and non-rapamycin using participants

Due to the overrepresentation of white participants in all conditions, this minor difference does not constitute a serious racial discrepancy between groups. Blacks, Pacific Islanders, and Native Americans were particularly underrepresented in the sample, with no more than 2 participants from any of these groups being part of the overall study. Asians and Hispanics were more represented in the sample, with participants from either group being evenly distributed between all conditions.

Additional medication taken with rapamycin

With the mean age of rapamycin users being over 60 years old and a greater prevalence of polypharmacy with age, which is the concomitant use of multiple medications, we sought to assess other medications survey respondents were taking in addition to rapamycin. The most commonly taken medications were for age-related indications, such as diabetes, cardiac, and cholesterol (Fig. 1). For most categories, males more frequently used additional medications. This can be attributed to the sample’s overall disparity between males and females. For parity, a ratio of 4:1 should be expected for each category of medicine. With that said, males are shown to use more common medications related to age-related diseases, whereas the most frequent medications that females use are either hormone or thyroid medications. Also, medications related to sexual dysfunction, cancer, and mental health were by far overrepresented in males. Finally, there were a few counts of opioid-related medication use as well as HIV-related medications. However, these counts were so minimal that they served as general outliers for the sample data. In general, this reflects prospective trends relating to health conditions that participants within the study may have, and the findings are expected as the rapamycin users were, on average, 61.9 years old with a range of up to 88 and 91 years of age for males and females, respectively. The data for reported medications consisted solely of prescription medications that a rapamycin user reported. The greatest number of medications that a single participant used was 13. The participant with the most varied medication usage was taking 7 different medications concurrently with rapamycin. While it remains unclear if drugs like metformin were used for diabetes management or healthspan purposes, our results indicate prevalent concurrent use of off-label rapamycin with other medications among older adults. A full breakdown of all the medications that participants in the study took is shown in Supplemental Table 1.

Fig. 1.

Percentage of participants taking rapamycin for greater than 90 days (n = 245) and taking prescription medications. Medications are grouped by medical condition (i.e., diabetes). Females are pink and males are blue

Rapamycin time, interval, and dosage

To characterize rapamycin use in survey participants, we evaluated the length of time, interval, and overall dosing. Most rapamycin users had used rapamycin for less than 40 months, with the average use length being 21.5 and 19.4 months for males and females, respectively (Fig. 2). While males have used rapamycin for longer than females, the general distribution of their use across the groups was similar. No difference existed between males and females in use interval (Fig. 3). Further, rapamycin use dosage in both males and females is similar, with males, on average, taking a marginally higher dosage of 6.2 mg per week in comparison to the female average of 5.7 mg per week (Fig. 4).

Fig. 2.

Rapamycin time of use. The number of months rapamycin was taken is displayed by a scatterplot distribution of all users with an interquartile range marked with horizontal lines. The same distributions for females and males follow with the addition of box and whisker plots. A table of the means, standard deviations, and ranges of rapamycin use length of each of the three groups is shown

Fig. 3.

Rapamycin interval of use. Interval in days in which subjects received rapamycin are displayed by a scatter plot with median horizontal range makers. All these subjects were on rapamycin for more than 90 days. This chart is accompanied by a table of the means, standard deviations, and ranges of rapamycin use intervals

Fig. 4.

Rapamycin dosage. These charts represent the dosage of rapamycin that a rapamycin user takes (per week in milligrams) and are displayed by a scatterplot with median and interquartile range markers for all users, females and males, respectively. These data are accompanied by a table of the means, standard deviations, and ranges of rapamycin dosage each of the three groups. This chart used data from rapamycin users that had been on rapamycin for more than 90 days

Oral health outcomes reported by rapamycin users

Most participants reported no oral health changes (181 out of 245, Table 3). Of those who reported oral health changes, 28 participants reported some positive changes to their oral health. Among the negative changes were self-reports of mouth ulcers.

Table 3.

Frequencies of oral health outcomes reported by rapamycin users. The frequencies and percentage of total users that reported oral health changes. The table is split by sex with the total number of participants per oral health outcome. Data from persistent ulcers and intermittent ulcers were taken from the subset of rapamycin users that reported ulcers. Missing data is excluded from the table

Of the 54 rapamycin users who reported ulcers, 50 reported intermittent ulcers that were transient and temporary, while 4 reported persistent ulcers. We then evaluated the dosage at which participants reported experiencing ulcers. The dosage for users reporting persistent was 3.6 mg/week, while the dosage for users reporting intermittent ulcers was higher at 6.87 mg/week (Fig. 5).

Fig. 5.

Rapamycin dose in relation to mouth ulcer frequency. The distribution of mouth ulcer type and rapamycin dose from self-reported incidences. A two-tailed, unpaired t test was completed. Significance set to p < 0.05. *p < 0.05

Due to rapamycin users taking multiple medications in addition to rapamycin, we evaluated the relationship between rapamycin dose and report of additional medications to oral health outcomes through logistic regression modeling. Initially, chi-square tests, Fisher’s exact tests, and logistic regressions were used, depending on the type of data available, to analyze for differences between demographics, rapamycin usage—length of time, dosage, and dosage interval—and usage of additional alternative medications regarding changes in oral health outcomes. Most analyses were not found to be statistically significant. The sole significant findings were related to participant reports of positive outcomes regarding their oral health in relation to rapamycin dosage and reported use of additional medications. Participants who used additional medications in addition to rapamycin were found to be 2.50 times (p < 0.05) less likely to report that they experienced positive oral health outcomes, and participants who used a higher dosage of rapamycin were 1.14 times (p < 0.05) more likely to report positive oral health outcomes per increased milligram of rapamycin they used per week (Figs. 6 and 7). The dark center line represents the line of best fit as given by the regression findings whereas the lighter wide band represents the confidence interval. Notably, the wide bands of the confidence interval denote a lack of certainty regarding the effect size of the significant findings of the regression.

Fig. 6.

Main effects of the logistic regression results of rapamycin dosage and use of additional medications on positive oral health outcomes. The center line represents the linear model of the regression and the larger bands represent the confidence interval for the model at any given point. Both models indicate the main effects of use of additional medications (binary, with 1 indicating use of additional medications and 0 indicating no use of additional medication) and rapamycin usage per week (in milligrams) on likelihood of a participant to report positive effects of rapamycin use. There were no significant interactions effects found within the model. The models are visual representations of a logistic regression fitted onto a linear regression chart using the “visreg” package in R

Fig. 7.

Case studies analyzing dental x-rays from rapamycin users. a Radiographs from similar fields of view and teeth were analyzed by OverJet AI by averaging the bone level quantification per tooth measured on b the x-ray. In case study 3, the rapamycin user had new restorative fillings on the analyzed teeth that confounded linear measurements. Hence, the analysis was not completed but demonstrates similar periodontal bone levels before and after rapamycin

Dental case studies

As part of the survey, we requested dental x-rays from participants taking off-label rapamycin to evaluate changes to bone levels around the teeth before and after rapamycin. The dental x-rays were analyzed for periodontal bone loss using Overjet, an AI-based, FDA-approved for periodontal bone loss quantification. In all 3 individuals taking off-label rapamycin, there was no detectable bone loss over 1–4 years. In case 3, final bone loss measurements were not compared as teeth #2(12), #13(25), and #14(26) underwent dental restorations, creating the landmark on the tooth to be closer to the periodontal bone confounding overall analysis.

Discussion

This study builds upon a secondary analysis of collected survey data from individuals using off-label rapamycin to enhance their healthspan. We show for the first time that most of the rapamycin users are also taking at least 3–4 other medications for age-related indications, such as diabetes or heart disease. Based upon our initial published reports and our findings in this study, off-label rapamycin use did not negatively interact with concomitant medications participants were taking. Additionally, we observed similar durations of rapamycin use between male and female users—approximately 21.5 months for males and 19.4 months for females. The dosage interval for both genders averaged around 7 days (7.8 days for males and 7.5 days for females). Despite comparable average intervals and dosage regimens, among 244 users, only 63 reported oral health changes. Thus, the majority of rapamycin users did not report changes in their oral health.

Due to the adverse side effects of taking rapamycin at higher dosages, it should be expected that using rapamycin at lower dosages may also retain some of those adverse side effects, such as mucositis, which is inflammation and ulceration of the mucous membranes, particularly in the mouth. In our survey participants, only 4 of the users reported persistent mouth ulcers, while 50 users experienced intermittent mouth ulcers, which users defined as disappearing with continued usage or emerging only early on during the regimen. Rapamycin and other mTOR inhibitors are FDA-approved as prophylaxis to prevent organ transplant rejection and are known to cause mouth sores/ulcers, commonly termed mTOR inhibitor–associated stomatitis (mIAS) (16). mIAS causes severe inflammation and sores in the mouth, negatively impacting treatment adherence and quality of life. The pain and discomfort often lead to an interruption or reduction in the dose and may lead to discontinuation until mIAS resolves. However, our study suggests that ulcers reported by our participants from low-dose, intermittent rapamycin are not as severe and debilitating as traditional mIAS but instead may resemble aphthous ulcers or canker sores.

Our survey data indicated that mouth ulcers tended to resolve despite continued rapamycin use, suggesting their non-severity, as participants, on average, have been continuously using rapamycin for nearly 20 months. The average off-label concentration was approximately 6 mg per week, significantly lower than the traditional dose of up to 10 mg daily or 70 mg per week (17). This reduction in frequency and dose could be one reason why reported ulcer incidence and severity were lower than expected. Intriguingly, our study found that users with lower doses experienced more persistent ulcers, indicating oral side effects may be more of an individualized response than dose dependent.

Most rapamycin users reporting oral health changes cited benefits such as “improved periodontal health,” “stronger teeth,” and “fewer cavities.” To assess one aspect of oral health, dental x-rays were obtained from rapamycin users to compare periodontal bone levels pre- and post-rapamycin use. Periodontal bone loss is one hallmark of periodontal disease [24–26], and published work has demonstrated an attenuation [20] and reversal [11] of periodontal bone loss in aging mice. We utilized Overjet, an FDA-approved AI tool for bone level quantification, to analyze three case studies where pre- and post-rapamycin dental x-rays were available. While subtle bone loss changes cannot be directly compared between two dental x-rays without consistent angulation when taking the x-rays, our results find no detectable bone loss and indicate that there is no exacerbation of periodontal bone loss in short-term rapamycin use in all cases. In one case (case 1), periodontal bone loss remained unaltered even after 4 years of off-label rapamycin use.

Taken together, our observations suggest that survey respondents used multiple medications alongside rapamycin, reported mouth ulcers not severe enough to stop rapamycin use, and rapamycin use did not worsen oral health or periodontal bone loss. An important consideration is that our analysis was based upon open-ended questions, such as “Please describe any positive effects that you may have experienced since taking rapamycin” or “Please describe any negative effects that you may have experienced since taking rapamycin.” Because of insufficient data collection, we could not analyze the oral health of non-users of rapamycin due to the initial survey design. However, many of the study limitations, like the self-reported nature of the data and lack of comprehensive oral health information, could be addressed through a double-blind, randomized clinical trial.

A prevalent concern within both clinical and general geroscience communities revolves around the occurrence of mouth sores during the administration of rapamycin. Dentists and oral health care providers routinely navigate and address mouth sores, which can be aphthous ulcers (canker sores), stomatitis, mucositis, or mIAS, within dental offices or hospitals. Our findings indicate that low-dose, off-label rapamycin use may cause mild aphthous-like ulcers or canker sores in a subset of individuals but does not appear to cause more severe mucositis or mIAS seen in organ transplant rapamycin users. Aphthous-like ulcers or canker sores are considered a minor concern to most oral health care providers due to established care and management protocols, and such ulcers often resolve spontaneously. Consequently, if the prospect of developing oral ulcers is a deterrent to utilizing rapamycin for potential improvements in healthspan, and maybe even lifespan, it accentuates the significance of regular visits to a dentist or an oral healthcare provider for individuals engaging in off-label rapamycin use.

Future studies should pursue a longitudinal approach encompassing more robust oral health measures, such as clinical measures of periodontal disease and gingivitis, as well as specific components of improving oral health. While a major limitation was the implementation of open-ended questions, longitudinal surveys over several months or years may be used on participants beginning off-label or low-dose rapamycin to determine if oral health improvements are linked to rapamycin use. Research into the use of low-dose rapamycin presents a relatively low potential for harm to oral health, particularly if only mild aphthous ulcers are present, where potentially the benefits may outweigh future risks.

Supplementary Information

Below is the link to the electronic supplementary material.

Funding

This work was supported by a Longevity Impetus Grant from the Norn Group to J.Y.A. and M.K.

Declarations

Conflict of interest

MK is a co-founder of the Optispan Geroscience, which has no material interest in rapamycin or rapamycin derivative production or sales at this time. AI, AN, and SZ are employees and/or shareholders of the Ageless Rx, a longevity focused telemedicine platform that sponsors several clinical trials, including interventional and observational efforts for the repurposed use of rapamycin. MG is currently the senior clinical manager at the Overjet Inc.