NMRA-335140

Navacaprant (NMRA-335140) was Neumora Therapeutics' lead asset, an oral once-daily selective kappa-opioid receptor (KOR) antagonist positioned as a non-monoaminergic monotherapy for major depressive disorder. All three Phase 3 KOASTAL studies missed their primary MADRS endpoint at week 6 with essentially zero drug-placebo separation: KOASTAL-1 posted MADRS change of -12.5 vs -12.5 (p=0.993), KOASTAL-2 -12.2 vs -12.0 (LSMD -0.3, p=0.813), and KOASTAL-3 -10.1 vs -10.8 (LSMD +0.7, drug numerically worse than placebo, p=0.480) [1][2][3][5][6]. Neumora terminated the program in the June 15, 2026 8-K, announced a ~35% workforce reduction ($10M annualized savings), and extended cash runway into Q3 2027 [6][7]. The collapse eliminated the flagship KOR-antagonist thesis in MDD, wiped roughly 80% of Neumora's equity value across the readout sequence, and, combined with J&J's earlier March 6, 2025 discontinuation of the aticaprant VENTURA Phase 3 program for insufficient efficacy, effectively closes selective KOR antagonism in MDD as a near-term commercial pathway [8].

First-in-class investigational compound, never approved anywhere. Program terminated June 15, 2026 [6]. Neumora ran a three-study monotherapy registration package at the 80 mg once-daily oral dose: KOASTAL-1 (NCT06029426, n=383), KOASTAL-2 (NCT06058039, n=430), and KOASTAL-3 (NCT06058013, n=422), plus a 52-week open-label safety extension (NCT06029439) [1][2][3][4]. KOASTAL-1 read out negative on January 2, 2025 (MADRS -12.5 vs -12.5, p=0.993), sending Neumora shares down about 80% in a single session [5]. The company pushed forward with KOASTAL-2 and KOASTAL-3, both of which also missed the primary MADRS endpoint at week 6, and announced program discontinuation in the June 15, 2026 8-K along with a ~35% workforce reduction and cash runway guidance into Q3 2027 [6][7]. No FDA designations were disclosed: no breakthrough therapy, no fast track, no accelerated pathway. A small bipolar II depression Phase 2 study (NCT06429722, n=18) was too underpowered to move the read. The database phase flag of 'phase3' is a legacy schema field reflecting the highest phase reached; the structured status is now terminated and no further commercial development of navacaprant in MDD is planned.

The kappa-opioid receptor (KOR) is one of three main opioid receptors in the brain. Its natural activator, a small peptide called dynorphin, gets released under stress and produces dysphoria, anhedonia (loss of the ability to feel pleasure), and social withdrawal in rodents and humans. The idea: block KOR, and you interrupt that stress-driven off-switch on the brain's reward circuitry, which could lift the pleasureless, low-motivation features of depression that SSRIs handle poorly. Preclinical support is real. KOR antagonists reverse anhedonia in rodent chronic-stress models, and PET imaging in depressed patients shows altered KOR binding patterns. Human validation, however, has now collapsed. ALKS-5461 (buprenorphine/samidorphan) received an FDA complete response letter in 2019 for adjunctive MDD, but it is not a clean test of selective KOR antagonism: buprenorphine is a mu-partial-agonist with mixed opioid receptor activity including partial KOR agonism, and samidorphan is primarily a mu-opioid receptor antagonist [9]. The two clean tests of pure selective KOR antagonism in MDD were navacaprant and aticaprant, and both failed. Navacaprant missed all three KOASTAL monotherapy Phase 3 trials with drug-placebo deltas of essentially zero [5][6]. Johnson & Johnson's aticaprant (JNJ-67953964), a highly selective KOR antagonist run at 10 mg once daily as adjunctive therapy in patients enriched for moderate-to-severe anhedonia, had its Phase 3 VENTURA program (NCT05455684, NCT05550532) discontinued on March 6, 2025 for insufficient efficacy in the target population [8]. Taken together, KOASTAL rules out selective KOR antagonism as MDD monotherapy in a broad moderate-to-severe population, and VENTURA rules out the adjunctive-plus-anhedonia-enrichment path. The mechanism is not disproven in every conceivable design (bipolar depression, PTSD, substance-use anhedonia, biomarker-defined subpopulations remain in principle), but the two best-resourced registrational shots at KOR in MDD both failed at pharmacodynamically adequate doses.

KOASTAL was a three-study registration package evaluating oral once-daily navacaprant 80 mg versus placebo as monotherapy in adults with moderate-to-severe MDD. The 80 mg dose was selected based on Phase 1 PET modeling projecting sustained KOR occupancy of ~90%, so subtherapeutic pharmacodynamic exposure is not a plausible explanation for the failure [11]. KOASTAL-1 (NCT06029426, n=383), KOASTAL-2 (NCT06058039, n=430), and KOASTAL-3 (NCT06058013, n=422) all used the same primary endpoint: change from baseline in the Montgomery-Asberg Depression Rating Scale (MADRS) total score at week 6 [1][2][3]. NCT06029439 was the parallel 52-week open-label extension for long-term safety and tolerability [4]. Design was conventional and appropriate for FDA registration: sample sizes powered to detect roughly a 2 to 3 point MADRS separation, standard 6-week readout window, MADRS entry criteria for moderate-to-severe symptoms, and placebo-controlled monotherapy. Monotherapy is a harder bar than adjunctive-therapy designs (which layer the study drug on top of an existing antidepressant) but produces cleaner efficacy claims if it works. The critical design vulnerability was placebo response. MDD registration trials chronically produce placebo MADRS improvements of 8 to 12 points, which narrows the window for drug-placebo separation and has killed many previously promising compounds. The Phase 2 study (NCT04221230) informed but did not cleanly validate the Phase 3 design: the pre-specified primary endpoint in the full efficacy population (which included patients with mild depression) was MISSED, and the positive readout Neumora carried forward came from a post-hoc moderate-to-severe MDD subgroup analysis [11]. That was a thin, subgroup-rescued signal on which to base a $200M+ three-study registration program, and it became the central retrospective critique after KOASTAL-1 failed. Observed drug-placebo results across the three Phase 3 trials: KOASTAL-1 MADRS -12.5 vs -12.5 (delta 0.0, p=0.993, 80 mg n=191 vs placebo n=192); KOASTAL-2 -12.2 vs -12.0 (LSMD -0.3, p=0.813); KOASTAL-3 -10.1 vs -10.8 (LSMD +0.7, drug numerically worse than placebo, p=0.480) [5][6]. This is a complete null across three trials, not a near-miss, which points at mechanism/population failure rather than execution or power. In KOASTAL-1, a pre-specified female-subgroup analysis showed MADRS -14.0 vs -11.4 (p=0.072, not statistically significant), and Neumora leaned on this as a rescue hypothesis for KOASTAL-2/3 without a formal enrichment amendment; the female signal did not replicate at meaningful magnitude in either later trial [5][6].

Our model estimates a 40% chance this drug is eventually approved. It starts from the historical base rate for Phase 3 drugs in this area (about 51%), then adjusts using ten facts about the trial and sponsor. What moves the number most: it is helped by a non-randomized design and its light or open-label blinding; it is held back by the sponsor's thin or weak approval record and weak or limited earlier-phase results. The other facts land near average for this stage, so they leave the estimate roughly where the base rate put it.

Efficacy failure was the primary risk and it materialized across all three trials. Four factors drove it. First, mechanism uncertainty compounded by class evidence that had already turned negative. Preclinical KOR-antagonism efficacy relies on stress-induced anhedonia models that translate imperfectly to heterogeneous human MDD, and no KOR-directed drug had reached approval in depression before navacaprant. J&J's aticaprant, the only other selective KOR antagonist in Phase 3 for MDD, was discontinued on March 6, 2025 for insufficient efficacy across the VENTURA program (NCT05455684, NCT05550532) despite anhedonia enrichment [8]. ALKS-5461 was rejected by the FDA in 2019 for adjunctive MDD, but its buprenorphine/samidorphan combination does not cleanly test selective KOR antagonism (see mechanism) [9]. Neumora was betting on a mechanism that nobody had converted to an approval, and mid-program the closest analog also failed. Second, thin Phase 2 signal. The Phase 2 primary endpoint MISSED in the full efficacy population, and the positive readout used to justify a $200M+ Phase 3 package was a post-hoc moderate-to-severe MDD subgroup analysis [11]. This was flagged at the time as a weak base. Third, placebo response. Registrational MDD studies routinely produce placebo MADRS improvements of 8 to 12 points (KOASTAL placebo arms landed at -10.8 to -12.5), and Neumora ran monotherapy trials in a broad moderate-to-severe MDD population without biomarker or anhedonia enrichment, so any patient-population heterogeneity diluted the signal further. Fourth, financial and execution risk on the sponsor side. Neumora is a 2019 Amgen spinout that IPO'd in September 2023, raising roughly $250M at a valuation near $2.7B. After KOASTAL-1's January 2, 2025 miss the stock lost about 80% of its value in a single session [5]. The June 15, 2026 8-K disclosed program discontinuation, a ~35% workforce reduction ($10M annualized savings partially offset by $2M one-time restructuring), and cash runway into Q3 2027 [6][7]. Strategic alternatives, further restructuring, or a reverse merger are plausible scenarios in the next twelve months.

Program is dead as an active asset. The remaining signal is what the double failure tells you about the broader KOR-antagonist thesis in MDD and about Neumora as a going concern. For the KOR class, both major selective registrational programs have now failed. J&J's aticaprant (adjunctive, 10 mg, anhedonia-enriched) was discontinued March 6, 2025 for insufficient efficacy in the VENTURA Phase 3 program (NCT05455684, NCT05550532) [8]. Neumora's navacaprant (monotherapy, 80 mg, broad moderate-to-severe MDD, PET-confirmed ~90% KOR occupancy) missed all three KOASTAL trials by June 15, 2026 [6][11]. The two programs tested different populations, different designs, and different doses at pharmacodynamically adequate KOR occupancy, and both failed. Selective KOR antagonism is therefore effectively closed as a near-term commercial pathway in MDD. The mechanism is not disproven in every conceivable indication (bipolar depression, PTSD, substance-use anhedonia, biomarker-defined subpopulations remain in principle) but the two best-resourced MDD shots at it are gone. The MDD field falls back to ketamine and esketamine, Axsome's Auvelity (dextromethorphan/bupropion), and next-wave neuroplasticity plays including psilocybin programs (Compass Pathways) and GABA-A modulators (Sage/Biogen zuranolone, approved in postpartum depression but rejected by FDA for adult MDD). For Neumora specifically, watch subsequent 10-Q filings for cash-runway execution against Q3 2027 guidance, pipeline reprioritization onto NMRA-511, NMRA-266, and NMRA-215, and any strategic-alternatives language. Remaining Amgen-derived assets are early-stage and the KOASTAL failures raise fair questions about the underlying translational bets. As a pipeline node, navacaprant is now a 'why it failed' case study, and the class-level signal from KOASTAL plus VENTURA is arguably more diagnostically important than either program alone.