This was a single-site, randomized, open-label, parallel-arm study conducted from October 2020 to December 2020 (NCT04598542). Randomization occurred according to a permuted block design with block size of 4. Enrolled participants were healthy volunteers who were randomized to Treatment Sequence (TS) 1, a single IA injection into the knee of 40 mg TCA followed 7 days later by one IA 0.07 mg LOR injection in the same knee; or TS 2, a single IA injection of 0.07 mg LOR into the knee followed 7 days later by one IA 40 mg TCA injection (Fig. 1). The primary objectives of the study were to determine the safety and tolerability of an IA LOR injection when given in temporal proximity to TCA; the secondary objectives were to determine the PK of IA LOR after injection and to assess potential PK interactions between IA TCA and LOR. All studies were conducted in accordance with the Declaration of Helsinki and the International Conference for Harmonisation Good Clinical Practice Guidelines E6 [5]. Institutional review board approval was provided by Advarra (Columbia, MD) (approval date 7 October 2020, approval reference MOD00817729). Participants consented to the collection of de-identified data in support of this study, as well as the publication of any findings from the study to medical conferences and journals. All participants provided written informed consent prior to participating in any study-related procedures. Adverse event severity was classified using Clinical Data Interchange Standards Consortium (CDISC) with preferred terms assigned according to the Medical Dictionary for Regulatory Activities (MedDRA).

Overview of study design and assessments by treatment sequence. TCA triamcinolone acetonide, LOR lorecivivint, PK pharmacokinetics

Eligible participants were adults aged 18–55 years in generally good health with body mass index (BMI) ≤ 32 kg/m2. Exclusion criteria included any chronic medical condition, history of knee inflammatory disease, IA injections, or medical procedures; pregnancy, breastfeeding, and a refusal to use birth control if sexually active and of reproductive potential; use of recreational drugs or any medication besides occasional acetaminophen within 30 days of study day 1; history of psychiatric disorders; and active infection or a chronic infection that may compromise immune or liver function.

All injections were performed on the right knee and were conducted according to the practitioner’s standard practice, which could include but did not require ultrasound guidance. Eligible participants checked into the clinic the evening before Day 1 (Day − 1) and remained in the clinic until Day 15 if in TS 1 or Day 22 if in TS 2. All participants had an end of study phone visit 14 days after leaving the clinic. The study was conducted at an inpatient phase 1 facility (Quotient Sciences, Miami, FL) (Fig. 1).

In TS 1, participants received IA TCA (40 mg) on Day 1 followed by IA LOR (0.07 mg) on Day 8 (Fig. 1). Additional study procedures and assessments were performed on Days 11 and 15, and the total study duration (including the screening period) for a given participant was up to 53 days. Blood was drawn for measurement of plasma TCA concentrations on Day 1 (before TCA dosing and 1, 2, 4, 6, 8, 10, and 12 h after TCA dosing), Day 2 (24 h after TCA dosing), Days 3, 5, and 8 (before LOR dosing and 1, 2, 4, 6, and 8 h after LOR dosing), Day 11, and Day 15. Blood was drawn for measurement of plasma LOR concentrations on Day 8 (before LOR dosing and 0.25, 0.5, 1, 2, 4, 6, and 8 h after LOR dosing).

In TS 2, participants received IA LOR (0.07 mg) on Day 1 followed by IA TCA (40 mg) on Day 8. Additional study procedures and assessments were performed on Days 10, 12, 15, 18, and 22, and total study duration for a given participant was up to 60 days. Blood was drawn for measurement of plasma LOR concentrations on Day 1 (before LOR dosing and 0.25, 0.5, 1, 2, 4, 6, and 8 h after LOR dosing), Day 8 (1, 2, 4, and 8 h after TCA dosing), Day 9 (24 h after TCA dosing), day 10, and Day 12. Blood was drawn for measurement of plasma TCA concentrations on Day 8 (before TCA dosing and 1, 2, 4, 6, 8, 10, and 12 h after TCA dosing), Day 9 (24 h after TCA dosing), and Days 10, 12, 15, 18, and 22.

All participants underwent general medical evaluations including physical examinations, knee examinations, recording of vital signs, and clinical laboratory evaluations. Recording of adverse events (AEs) started following informed consent and continued at all subsequent visits until the participant completed the end of study phone visit. For each treatment sequence, treatment-emergent AEs (TEAEs) were categorized by “epoch”, with epoch 1 spanning the time from the first injection until the second injection, and epoch 2 spanning from the second injection until the end of the study. Relatedness of AEs was only assessed by investigators for relationship to LOR or LOR injection.

PK properties were analyzed by determining plasma LOR and TCA concentrations at the described time points (see “Study Protocol” section). Plasma concentrations for TCA were analyzed using validated methods at Covance, Inc, with a lower limit of quantification of 20.0 pg/mL. Plasma concentrations for LOR were analyzed using validated methods at Charles River Laboratories, with a lower limit of quantification of 0.100 ng/mL.

All treated participants were included in all analyses. Baseline (prior to the first study injection) characteristics included age, sex, ethnicity, race, height, weight, and BMI (Table 1). When PK statistics were calculated for TCA, values below the lower limit of quantification (LLOQ) of 20.0 pg/mL were set to 1/2 LLOQ. For TCA, median value for Tmax (time taken to reach the maximum concentration) and geometric mean values for half-life, Cmax (maximum serum concentration), and area under the concentration curve (AUC) from baseline to 168 h post injection (AUC0–168) and AUC from baseline to infinity (AUC0–inf) were determined. In order to establish equivalence and no interaction between TCA and LOR on drug availability, two one-sided t tests (TOSTs) were used to compare the ratios of the geometric means for both AUC and Cmax between the treatment sequences. The results of the PK TOSTs were reported as ratios and combined 90% confidence intervals.