Last reviewed 2026-06-01 · How we verify

Letrozole ISM

Rovi Pharmaceuticals Laboratories · Phase 1 active Small molecule ✓ Verified Jun 2026

Letrozole ISM is a Small molecule drug developed by Rovi Pharmaceuticals Laboratories. It is currently in Phase 1 development. Also known as: Femara, 4,4'-(1H- 1,2,4-Triazol-1-ylmethylene)dibenzonitrile.

Letrozole ISM is a small molecule that inhibits the cytochrome P450 19A1 enzyme, specifically targeting aromatase. It is used in a Phase I clinical trial (NCT03401320) to evaluate its pharmacokinetics, safety, and tolerability in healthy post-menopausal women.

Likelihood of approval

9.6% vs 9.6% industry baseline

If approved by FDA: likely 2033–2036

Steps remaining: Phase 2 → Phase 3 → NDA/BLA submission

Confidence: Medium

Why this estimate

Baseline phase 1 → approval rate +9.6pp
Industry-wide phase 1 drugs reach approval ~9.6% of the time (BIO/Informa 2023 industry benchmark across all therapeutic areas).

Predicted approval windows by jurisdiction (conditional on FDA approval)

Regulator	Country	Likely year	Lag vs FDA
FDA	US	2033–2036	—
EMA	EU	2034–2037	+0.7 yr
MHRA	GB	2034–2037	+0.7 yr
Health Canada	CA	2034–2038	+0.9 yr
TGA	AU	2034–2038	+1.2 yr
PMDA	JP	2034–2038	+1.5 yr
NMPA	CN	2035–2039	+2.3 yr
MFDS	KR	2034–2038	+1.4 yr
CDSCO	IN	2034–2039	+1.8 yr
ANVISA	BR	2035–2039	+2.3 yr

Hover any row for the lag rationale. Lag estimates are reduced when the drug has FDA Breakthrough or EMA PRIME designation (sponsors file globally in parallel).

Estimate based on the BIO/Informa industry phase transition rates plus per-drug modifiers for therapeutic area, sponsor type, FDA designations, mechanism, and trial design. Per-jurisdiction lags from Tufts CSDD international approval studies. Not investment, clinical or regulatory advice. Methodology: /methodology#likelihood.

At a glance

Generic name	Letrozole ISM
Also known as	Femara, 4,4'-(1H- 1,2,4-Triazol-1-ylmethylene)dibenzonitrile
Sponsor	Rovi Pharmaceuticals Laboratories
Modality	Small molecule
Phase	Phase 1

Approved indications

No approved indications tracked.

Common side effects

No common side effects on file.

Key clinical trials

Evaluation of IM Letrozole ISM® Pharmacokinetics, Safety, and Tolerability in Healthy Post-menopausal Women (LISA-1) (PHASE1)

Primary sources

Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.

Source	Used for
ClinicalTrials.gov	Trial enrolment, design, endpoints, results

Competitive intelligence

For the full competitive landscape — auto-detected comparators, recent regulatory actions across the set, upcoming PDUFA, patent timeline, sponsor landscape:

Letrozole ISM CI brief — competitive landscape report
Letrozole ISM updates RSS · CI watch RSS
Rovi Pharmaceuticals Laboratories portfolio CI

Frequently asked questions about Letrozole ISM

What is Letrozole ISM?

Letrozole ISM is a Small molecule drug developed by Rovi Pharmaceuticals Laboratories.

Who makes Letrozole ISM?

Letrozole ISM is developed by Rovi Pharmaceuticals Laboratories (see full Rovi Pharmaceuticals Laboratories pipeline at /company/rovi-pharmaceuticals-laboratories).

Is Letrozole ISM also known as anything else?

Letrozole ISM is also known as Femara, 4,4'-(1H- 1,2,4-Triazol-1-ylmethylene)dibenzonitrile.

What development phase is Letrozole ISM in?

Letrozole ISM is in Phase 1.

Manufacturer: Rovi Pharmaceuticals Laboratories — full pipeline
Also known as: Femara, 4,4'-(1H- 1,2,4-Triazol-1-ylmethylene)dibenzonitrile

Primary sources · FDA · ClinicalTrials.gov · EMA · SEC EDGAR · ChEMBL · Wikidata · full sourcing