TNX - 601 CR*: a Once - Daily Formulation of Tianeptine in Development for the Treatment of Major Depressive Disorder Gregory M Sullivan 1 , David T Hsu 1 , Ashild Peters 1 , Perry Peters 1 , Siobhan Fogarty 1 , Regina K

Tonix Pharmaceuticals Holding Corp. 8-K

TNX - 601 CR*: a Once - Daily Formulation of Tianeptine in Development for the Treatment of Major Depressive Disorder Gregory M Sullivan 1 , David T Hsu 1 , Ashild Peters 1 , Perry Peters 1 , Siobhan Fogarty 1 , Regina Kiu 1 , Bernd Meibohm 2 , Seth Lederman 1 1 Tonix Pharmaceuticals Inc, 2 University of Tennessee Health Sciences Center *TNX - 601 CR is an investigational drug and has not been approved for any indication INTRODUCTION Tianeptine A typical tricyclic antidepressant with a novel mechanism of action M arketed for depression in Europe, Asia and Latin America > 30 years Not commercialized in United States (US) or United Kingdom (UK) Comparable efficacy to SSRIs and TCAs ; better tolerability P rominent anxiolytic effects in depression studies Mechanism of Tianeptine's Antidepressant Effect No affinity for traditionally targeted CNS receptors/transporters in depression Has i ndirect inhibitory modulation of glutamatergic activity, via AMPA and NMDA receptors 1 Demonstrated to promote release of BDNF and adaptive neural plasticity 1 Unique n europrotective properties opposing effects of chronic stress Active primary metabolite MC 5 has longer elimination half - life and comparable behavioral effects W eak binding to and agonism of human - opioid receptor (MOR) make it highly unlikely that it plays a role in antidepressant effect of tianeptine at standard therapeutic dose Weak binding to human MOR - K i : 383 nM 2 ; 768 nM 3 W eak agonist activity 4 (EC 50 - arrestin 2 : 3262 nM ; EC 50 Mini - Gi : > 1 x 10 4 nM ) Yet if high doses are ingested (in range of 8 X - 80 X antidepressant dose), the off - target MOR activity poses a danger for abuse, dependence, and their sequelae Improved Formulation for US Market Desirable Marketed form of tianeptine is amorphous tianeptine sodium 12 . 5 mg (Stablon / Coaxil ) Dosing is three - times daily (TID) in depression for total daily dose of 37 . 5 mg Tonix identified a new oxalate crystalline salt of tianeptine (Patent : US 10 , 946 , 027 B 2 , 3 / 16 / 2021 ) Tianeptine oxalate has improved pharmaceutical properties suitable for development of a controlled - release once daily ( QD) formulation Phase 1 Formulation Development Pharmacokinetic Studies C ompared the pharmacokinetics (PK) and safety of immediate - release (IR) tianeptine oxalate 13 . 1 mg (TNX - 601 IR) to tianeptine sodium (Stablon) 12 . 5 mg (tianeptine base 11 . 9 mg in both) Assessed several novel modified - release (MR) prototype formulations of tianeptine oxalate salt Highlighted is the PK in fasted and fed states of TNX - 601 MR 1 39 . 4 mg, the selected MR prototype formulation for development as a QD controlled - release (CR) treatment for major depressive disorder (MDD) Final Formulation, TNX - 601 CR, for Testing in Phase 2 Study of MDD Due to potential for diversion and abuse of high dosages of tianeptine for its weak MOR activity, naloxone 1 mg is included to mitigate potential for parenteral (intravenous, insufflation) abuse Oral naloxone is 2 % bioavailable ; 1 mg is a non - therapeutic ingredient at tianeptine's therapeutic dose Final formulation for planned Phase 2 clinical study: TNX - 601 CR (tianeptine oxalate 39.4 mg and naloxone 1 mg controlled - release tablets) METHODS www.tonixpharma.com Figure 1. Study Sequence Study TNX - TI - P101 S ingle center, open - label, 6 sequential period study Determined PK and relative bioavailability of TNX - 601 IR 13 . 1 mg compared to Stablon 12 . 5 mg For a QD formulation, 3 MR prototypes tested 12 healthy adult male and female subjects received single oral doses of IR and MR formulations in 6 periods Each period followed same study design ( Figure 1 ) Subjects confined to clinical unit evening prior to dosing (Day - 1 ) through 48 hrs post - dosing At least 7 - day washout between periods MR Tablet Formulation Prototypes A 2 - D design space for m atrix prototypes was used with flexibility to modify release rate via changing polymer content/composition and drug dose in response to emerging clinical PK data R elative bioavailability of TNX - 601 IR formulation was compared to Stablon Food effects determined for selected TNX - 601 MR 1 prototype on plasma PK (tianeptine & MC 5 ) Quotient Sciences, Nottingham, UK responsible for manufacture of TNX - 601 IR and three prototype MR formulations according to GMP ; Quotient Sciences' MHRA - licensed facility Reference product Stablon acquisitioned by Quotient P lasma concentrations of tianeptine & MC 5 determined using validated methods at LGC Ltd, Fordham, Cambridgeshire , UK . LLQ : 2 ng/mL for tianeptine ; 1 ng/mL for MC 5 MHRA approval granted for the Clinical Trial Authorisation (CTA) application for study Statistical Analyses Formal analyses performed on PK parameters C max , AUC 0 - last and AUC 0 - inf for tianeptine and MC 5 , analyzed using mixed modelling techniques after natural logarithmic transformation . Tables 1 & 2 show the geometric means and for results of pairwise comparisons, a djusted geometric mean ratios and 90 % confidence intervals (CIs) are presented with p - values For plasma PK concentrations in Figures 2 & 3 , arithmetic means and standard deviations are shown S afety Population : all subjects who received 1 dose IP . Safety assessed by adverse events (AEs), Columbia Suicide Severity Rating Scale (C - SSRS), physical exams, vital signs, ECG and labs Table 1. PK Parameters of Plasma Tianeptine & MC5 with Stablon and TNX - 601 IR The following PK parameters are displayed for tianeptine and active metabolite MC5 in Tables 1 & 2 : AUC 0 - 24 : Area under the curve from time 0 to 24 h post - dose for plasma concentration AUC 0 - inf : Area under the curve from time 0 extrapolated to infinity for plasma concentration C max : Maximum observed concentration AUC extrap : Percentage of AUC 0 - inf extrapolated beyond last measurable concentration T max : Time of maximum observed concentration T 1/2 : Apparent elimination half - life CL/F (for plasma tianeptine only) : Apparent total body clearance calculated after a single (non - IV) administration where F (fraction of dose bioavailable) is unknown Vz /F (for plasma tianeptine only) : Apparent volume of distribution based on terminal phase calculated after single (non - IV) administration where F (fraction of dose absorbed) is unknown F rel : Relative bioavailability based on C max , AUC 0 - last and AUC 0 - inf in the two sets of group comparisons Pharmacokinetic Results : PK results for plasma tianeptine and metabolite MC 5 are presented for TNX - 601 IR 13 . 1 mg in comparison with Stablon 12 . 5 mg in Table 1 (below) and Figure 2 (top of third column), both in a fasted state . For AUC 0 - last and AUC 0 - inf , TNX - 601 IR 13 . 1 mg had greater relative bioavailability than Stablon by 7 % for tianeptine and 14 - 15 % for MC 5 ( Table 1 ) . Inter - subject variability for exposure (AUC & C max ) was moderate and unaffected by salt form (Stablon 31 . 9 - 34 . 2 % ; TNX - 601 IR 28 . 2 - 34 . 5 % ) . Stablon 12.5 mg N=11 TNX - 601 IR 13.1 mg N=12 Stablon 12.5 mg N=11 TNX - 601 IR 13.1 mg N=12 Parameter (Mean) Tianeptine Metabolite MC5 AUC 0 - 24 ( ng.h /mL) 884 943 490 556 AUC 0 - last ( ng.h /mL) 872 934 580 664 F rel AUC 0 - last (%) 105.18 [101.47, 109.02], p=0.029 112.08 [106.98, 117.43], p=0.001 AUC 0 - inf ( ng.h /mL) 890 955 604 695 F rel AUC 0 - inf (%) 105.36 [101.46, 109.42], p=0.031 112.98 [107.87, 118.34], p<0.001 C max (ng/mL) 229 237 51.4 55.0 F rel C max (%) 102.07 [95.05, 109.61], p=0.61 104.67 [97.16, 112.77], p=0.29 AUC extrap (%) 1.808 1.919 3.592 3.954 T max (h) a 1.500 1.025 3.000 3.000 T 1/2 (h) 3.140 3.525 9.309 9.893 CL/F (mL/min) 223 208 *ND *ND Vz /F (L) 60.6 63.4 *ND *ND RESULTS Presented at CNS Summit 2021, Nov 7 - 10, 2021; Poster Sessions Nov 8 & 9, 5:00 PM - 7:00 PM EST Figure 2. Mean Tianeptine and MC5 Concentrations for Stablon and TNX - 601 IR PK results for plasma tianeptine and MC 5 are presented for selected prototype TNX - 601 MR 1 39 . 4 mg in fasted and fed states in Table 2 (below) and Figure 3 (top of 4 th column) . The C max was significantly greater in the fed state for both tianeptine and MC 5 , by 40 % and 34 % , respectively . Whereas, AUC 0 - last was lower by 10 % in the fed state for tianeptine only . The T 1 / 2 for TNX - 601 MR 1 39 . 4 mg was numerically reduced in fed state for tianeptine (not statistically compared) . Figure 3 shows the extended elevations of plasma tianeptine and MC 5 from TNX - 601 MR 1 over daytime hours compared with TNX - 601 IR in Figure 2 . Comparing PK of TNX - 601 MR 1 39 . 4 mg and predicted Stablon 12 . 5 mg TID dosing (data not shown), plasma tianeptine AUC 0 - 24 was 20 % lower, C max was not significantly different, and neither differed for MC 5 . Table 2. PK Parameters of Plasma Tianeptine & MC5 with TNX - 601 MR1 in Fasted and Fed States TNX - 601 MR1 39.4 mg (fasted) N=12 TNX - 601 MR1 39.4 mg (fed) N=12 TNX - 601 MR1 39.4 mg (fasted) N=12 TNX - 601 MR1 39.4 mg (fed) N=12 Parameter (Mean) Tianeptine Metabolite MC5 AUC 0 - 24 ( ng.h /mL) 2040 1990 1220 1270 AUC 0 - last ( ng.h /mL) 2300 2060 1750 1700 F rel AUC 0 - last (%) 89.22 [81.59, 97.56], p=0.043 97.02 [90.55, 103.96], p=0.45 AUC 0 - inf ( ng.h /mL) 2360 2230 2030 1830 F rel AUC 0 - inf (%) 92.81 [84.63, 101.77], p=0.17 93.57 [86.25, 101.51], p=0.17 C max (ng/mL) 230 321 76.3 102 F rel C max (%) 139.70 [114.19, 170.91], p=0.013 134.19 [117.30, 153.51], p=0.002 AUC extrap (%) 1.944 1.691 6.821 6.198 T max (h) a 3.500 5.000 8.042 8.000 T 1/2 (h) 6.874 5.050 11.306 11.175 CL/F (mL/min) 252 266 *ND *ND Vz /F (L) 150 116 *ND *ND Safety Results : Single doses of Stablon 12 . 5 mg fasted (reference), TNX - 601 IR 13 . 1 mg fasted, prototype TNX - 601 MR 1 39 . 4 mg fasted and fed, prototype TNX - 601 MR 2 39 . 4 mg fasted, prototype TNX - 601 MR 3 50 mg fed # and TNX - 601 MR 3 50 mg fasted # were well tolerated in 12 healthy male ( 7 ) and female ( 5 ) subjects . Two subjects reported treatment emergent adverse events (TEAEs) deemed possibly related to study drug, namely somnolence (on TNX - 601 IR 13 . 1 mg fasted) and headache (on TNX - 601 MR 1 39 . 4 mg fed), while all other TEAEs were deemed not related to study drug . All TEAEs were mild in severity, and all resolved by end of the study . There were no significant laboratory, vital signs, ECG, C - SSRS or physical examination findings . The two possibly related TEAEs, headache and somnolence, are both described in the Stablon Summary of Product Characteristics (v . 27 May 2016 ) as common (defined 1 / 100 , < 1 / 10 ) . # Group sizes for groups marked with hashmark were N= 6 each ; all other groups were N= 12 Upcoming Phase 2 Trial of TNX - 601 CR in MDD CONCLUSIONS Following single oral administration of TNX - 601 IR 13 . 1 mg, there was greater relative bioavailability of tianeptine and MC 5 compared to single dose of Stablon 12 . 5 mg . Yet the PK curves were notably similar, and differences were not clinically relevant given TNX - 601 IR 13 . 1 mg in tianeptine relative bioavailability (AUC 0 - last and AUC 0 - inf ) at only 7 % over Stablon , no difference in C max for tianeptine and MC 5 , and ~ 15 % increase in relative bioavailability of MC 5 . Inter - subject variability in plasma tianeptine and MC 5 exposure was unaffected by salt form, sodium versus oxalate . S ingle dose of TNX - 601 MR 1 39 . 4 mg compared with predicted PK for Stablon 12 . 5 mg TID dosing showed a similar tianeptine C max (within ~ 11 % of each other) and an AUC 0 - 24 which was ~ 20 % less than that predicted ; while exposure to MC 5 was similar to that predicted, C max (w/ i 9 % ) and AUC 0 - 24 (w/ i 1 % ) . Administration of TNX - 601 MR 1 39 . 4 mg tablet with a high fat breakfast demonstrated a delay in absorption and an increase in C max for t ianeptine and MC 5 of 40 % and 34 % , respectively, compared to fasted . Whereas by AUC 0 - last in f ed state, there was a reduction by 10 % in in tianeptine exposure, and no significant difference in AUC 0 - inf for tianeptine, or for either AUC 0 - last or AUC 0 - inf for MC 5 . Thus, despite higher peak exposure in fed state ( C max ), overall exposure by AUC was similar or minimally reduced . The PK profile of TNX - 601 MR 1 39 . 4 mg tablet in Figure 3 is suitable for once - daily dosing, providing a similar profile for tianeptine and MC 5 as that resulting from Stablon 12 . 5 mg when dosed TID in daytime . As a result of this work, a QD controlled - release formulation, TNX - 601 CR, was subsequently developed which contains 39 . 4 mg of tianeptine oxalate and 1 mg of naloxone (included to mitigate high dose parenteral abuse) . This formulation will be advanced to clinical testing in an upcoming US Phase 2 trial . Tonix is sponsoring an upcoming US trial, TNX - TI - M 201 , of TNX - 601 CR (tianeptine oxalate 39 . 4 mg and naloxone 1 mg controlled - release tablets) for once daily treatment of MDD, currently in IND preparation Design is a Phase 2 , randomized, double - blind, placebo - controlled, parallel group study to evaluate the efficacy and safety of TNX - 601 CR monotherapy versus placebo in MDD Treatment duration is 6 weeks, preceded by up to 5 weeks of screening and followed by a 2 - week safety follow - up period (total up to 13 weeks of participation) Approximately 260 individuals with MDD will be randomized 1 : 1 to two arms of 130 each at approximately 25 - 30 US sites Primary efficacy endpoint will be the change from Baseline to Week 6 in Montgomery - sberg Depression Rating Scale (MADRS) score Enrollment is estimated to start by April 2022 CITATIONS 1. McEwen BS, Chattarji S, Diamond DM, Jay TM, Reagan LP, Svenningsson P, Fuchs E. The neurobiological properties of tianeptine (Stablon): from monoamine hypothesis to glutamatergic modulation. Mol Psychiatry . 2010 Mar;15(3):237 - 49. PMID: 19704408 2. Gassaway MM, Rives ML, Kruegel AC, Javitch JA, Sames D. The atypical antidepressant and neurorestorative agent tianeptine is a - opioid receptor agonist. Transl Psychiatry . 2014 Jul 15;4(7):e411. PMID: 25026323. 3. PDSP Certified Data. https://pdsp.unc.edu/pdspweb/ 4. Vandeputte MM, Cannaert A, Stove CP. In vitro functional characterization of a panel of non - fentanyl opioid new psychoactive substances. Arch Toxicol . 2020 Nov; 94(11):3819 - 3830. PMID: 32734307. a median; *ND = not done a median; *ND = not done Figure 3. Mean Tianeptine and MC5 Concentrations for TNX - 601 MR1 in Fasted and Fed States