Table 7 Compounds discontinued or likely to have been discontinued from clinical development since 2018 or the previous review [23]

From: Antibiotics in the clinical pipeline as of December 2022

Name (synonym) [References]

Compound class (lead source); mode of action

Last known status and indication

iclaprim [374]

trimethoprim (S); dihydrofolate reductase (DHFR)

NDA, IV/po; ABSSSI (Motif Bio) – FDA required an additional phase-III trial and development was halted

SQ109 [375,376,377,378]

“ethambutol analog” (S); mycolic acid transporter inhibitor (cell wall)

po; TB (Sequella) – a Russian phase II/III trial was completed in 2017 by Infectex [362, 363]; funding for further development is being sought by Sequella (Rockville, MD, USA)

ridinilazole (SMT 19969) [379,380,381,382]

bis-benzimidazole (S) [potential new class]; cell division inhibitor

Phase-III; po topical; CDI (Summit) – ridinilazole was non-superior compared to vancomycin in terms of clinical response, and an additional phase-III trial would have been required [374]

ancremonam (BOS-228, LYS228) [383, 384]

monobactam (NP); PBP (cell wall)

IV; cUTI and cIAI (Boston Pharmaceuticals) – licensed by Novartis to Boston Pharmaceuticals (Cambridge, MA, USA) in July 2018, but there has been no further development

OPS-2071 [385, 386]

fluoroquinolone (S); DNA gyrase

po topical; CDI (Otsuka) – discontinued in 2020 for CDI and Crohn’s Disease

TP-6076 [387, 388]

tetracycline (NP); protein synthesis inhibition

IV; G-ve (Tetraphase) – phase-I trial (NCT03691584) was completed in December 2019 and there has been no further development; Tetraphase was acquired by La Jolla Pharmaceutical in July 2020, who are now part of Innoviva (Burlingame, CA, USA)

TP-271 [389,390,391]

tetracycline (NP); protein synthesis inhibition

IV/po; G+ve/ G-ve (Tetraphase) – phase-I trials (e.g., NCT03024034) completed in 2018 and there has been no further development; Tetraphase was acquired by La Jolla Pharmaceutical in July 2020, who are now part of Innoviva (Burlingame, CA, USA)

SPR741 + β-lactam [392, 393]

polymyxin (NP); membrane permeabilizer (cell wall)

IV; G-ve (Spero) – phase-I trials (NCT03022175 and NCT03376529) completed in 2017 and development was discontinued in 2020

GT-1 (LCB10 0200) [394, 395]

cephalosporin siderophore (NP); PBP (cell wall)

IV (Geom) – phase I trial (ACTRN12618001980224) started in March 2019 but was halted due to safety concerns

BCM-0184

not disclosed

po (& topical); G+ve (Biocidium) – phase-I trial was not registered and there has been no update

niclosamide (ATx201) [396]

salicylanilide (S); oxidative phosphorylation; quorum sensing

topical; H. pylori; impetigo (Union Therapeutics) – phase-II trials (NCT03009734 and NCT03429595) finished in 2018; only listed in their pipeline for COVID-19 prophylaxis (NCT04932915)

auranofin [236]

auranofin (S); thiol-redox homeostasis

po; TB (The Aurum Institute) – phase-II trial (NCT02968927) has not been updated since January 2019

DSTA4637S [397, 398]

mAb rifamycin conjugate (ADC); RNA synthesis

IV; G+ve (Genentech) – phase-I trial (NCT03162250) completed in January 2020 but DSTA4637S is not listed on their pipeline

  1. ABSSSI acute bacterial skin and skin structure infections, ADC antibody drug conjugate, CDI C. difficile infections, cIAI complicated intra-abdominal infections, cUTI complicated urinary tract infections, G-ve Gram-negative, G+ve Gram-positive, NP natural product, PBP penicillin binding protein, S synthetic, TB tuberculosis