# MANIFEST-2

Source: https://onco.cc/trials/manifest-2/  
OnCo record `manifest-2` (Trial). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

MANIFEST-2 found that adding the BET inhibitor pelabresib to ruxolitinib shrank spleens in nearly twice as many people with myelofibrosis, but the improvement in symptoms did not reach statistical significance, leaving the drug's approval uncertain.

## Summary

BET proteins read the epigenetic marks that drive the inflammatory and fibrotic programme of myelofibrosis. MANIFEST-2 randomised 430 patients with myelofibrosis who had not yet received a JAK inhibitor to ruxolitinib with pelabresib or with placebo. The primary endpoint was a spleen volume reduction of 35 percent or more at week 24; the key secondary endpoint was a 50 percent or greater fall in total symptom score.

The combination roughly doubled the spleen response rate, meeting the primary endpoint, and showed improvements in bone marrow fibrosis and anaemia, but the symptom endpoint favoured the combination without reaching statistical significance. Regulators asked for more data, and the drug had not been approved by the time of writing.

## Fields

- Kind: Trial
- Status: mixed
- Last checked: 2026-09-17
- Tags: subtype-trials
- Registry id: NCT04603495
- Phase: 3
- Setting: JAK inhibitor-naive myelofibrosis: ruxolitinib with the BET inhibitor pelabresib or placebo
- Sponsor: Novartis (Constellation, MorphoSys)
- Enrolled: 430
- Result: Pelabresib plus ruxolitinib roughly doubled the week-24 spleen volume response over ruxolitinib alone; the symptom endpoint did not reach significance.
- Outcomes: Spleen volume reduction >=35% at week 24: Pelabresib + ruxolitinib 65.9% vs Placebo + ruxolitinib 35.2%; Total symptom score reduction >=50% at week 24 (TSS50): Pelabresib + ruxolitinib 52.3% vs Placebo + ruxolitinib 46.3%; Absolute change in total symptom score at week 24: Pelabresib + ruxolitinib -15.99 points vs Placebo + ruxolitinib -14.05 points; Grade 3 or higher anaemia: Pelabresib + ruxolitinib 23.1% vs Placebo + ruxolitinib 36.5%; Grade 3 or higher thrombocytopenia: Pelabresib + ruxolitinib 13.2% vs Placebo + ruxolitinib 6.1%

## Sources

- ClinicalTrials.gov NCT04603495: https://clinicaltrials.gov/study/NCT04603495

## Connected records

- cancers: [Myeloproliferative neoplasms (PV, ET, myelofibrosis)](https://onco.cc/cancers/myeloproliferative-neoplasms/), [Primary myelofibrosis](https://onco.cc/cancers/primary-myelofibrosis/)
- drugs: [Pelabresib](https://onco.cc/drugs/pelabresib/), [Ruxolitinib](https://onco.cc/drugs/ruxolitinib/)
- companies: [MorphoSys (Novartis)](https://onco.cc/companies/morphosys/), [Novartis](https://onco.cc/companies/novartis/)
- people: [Raajit K. Rampal](https://onco.cc/people/raajit-rampal/)

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