# ProJenX

> ProJenX is a New York City clinical-stage biotechnology company developing prosetin, a first-in-class, oral, brain-penetrant MAP4K inhibitor for amyotrophic lateral sclerosis (ALS) and other neurodegenerative brain diseases. Spun out of a two-decade collaboration between the nonprofit Project ALS and Columbia University researchers, ProJenX is built on the discovery that inhibiting MAP4 kinases protects motor neurons across multiple patient-derived stem cell models of ALS. The company is running the PRO-101 Phase 1b trial in people living with ALS.

- **Founded:** 2021
- **Headquarters:** New York, New York, United States
- **Founders:** Erin Fleming (Co-Founder & Chief Operating Officer), Hynek Wichterle (Scientific Co-Founder, Board Director & Senior Scientific Advisor)
- **Team size:** ~9 employees
- **Products:** Prosetin, PRO-101 clinical program
- **Notable:** Developed prosetin, the first brain-penetrant MAP4K inhibitor therapy to enter clinical trials, Closed a $15M Series A financing in November 2023, Secured FDA removal of a partial clinical hold on the prosetin Phase 1 program

## Products & services

- **Prosetin** — A first-in-class, novel, selective, oral, brain-penetrant MAP4K (MAP4 kinase) inhibitor discovered on the finding that MAP4K inhibition confers potent motor neuron protection across multiple patient stem cell-derived models of ALS. Optimized for potency, motor neuron rescue, and preferential CNS distribution; targets endoplasmic reticulum (ER) stress shared across ALS subtypes.
- **PRO-101 clinical program** — A Phase 1b trial evaluating prosetin's safety, tolerability, pharmacokinetics and target engagement in people living with ALS, fully enrolled with 41 participants across five dose levels, followed by a 2-year open-label extension.

## Achievements

- Developed prosetin, the first brain-penetrant MAP4K inhibitor therapy to enter clinical trials
- Closed a $15M Series A financing in November 2023
- Secured FDA removal of a partial clinical hold on the prosetin Phase 1 program
- Received European regulatory authorization for the first study of prosetin in people with ALS
- Fully enrolled the PRO-101 Phase 1b trial with 41 ALS participants across five dose levels
- Won a $1M Hoffman ALS Clinical Trials Award from the ALS Association
- Demonstrated novel, exposure-related target engagement (decrease in phosphorylated MAP2K4) in patient blood cells

## Latest updates

- **2026-06** — ProJenX reported a development update: PRO-101 fully enrolled with 41 ALS participants, no serious adverse events, therapeutic exposure at top doses, and statistically significant target engagement; a 2-year open-label extension is ongoing. Data presented at ENCALS 2026 in Madrid.
- **2024-06** — ProJenX received a $1M Hoffman ALS Clinical Trials Award from the ALS Association.
- **2024** — FDA removed the partial clinical hold on the prosetin Phase 1 program.
- **2023-11** — ProJenX announced the initial closing of a $15M Series A financing and appointed Rick Hartz to the Board of Directors.

## Links

- Website: https://projenx.com
- LinkedIn: https://www.linkedin.com/company/projenx-inc
- Twitter/X: https://twitter.com/projenx

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Last updated: 2026-07-18