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RSO-021 Phase ½ Clinical Trial

Patients with Malignant Pleural Effusion due to Advanced/Metastatic Solid Tumors including Mesothelioma

A Translational Phase 1/2 Dose-Escalation and Expansion Study to Determine Safety, Tolerability, and Recommended Phase 2 Dose of RSO-021 

Treatment type

Second line and beyond

Dose Escalation

RSO-021 administered in increasing doses as a solution for pleural infusion through an indwelling IP catheter, administered as a single dose on Day 1 of each week of a 21-day treatment cycle


6+ UK referring sites

Primary Objective

- Safety

- Tolerability

- Toxicity profile


Malignant Pleural Effusion, Malignant Pleural Mesothelioma, Mesothelioma Solid Tumor

Drug RSO-021

A naturally-occurring, sulfur-rich, cyclic oligopeptide antibiotic of the thiopeptide class.


Chief Investigator:

Dr. James Spicer (Guy's Hospital London),

Principal Investigators:

Dr. Alastair Greystoke (Newcastle Univ.),

Dr. Fiona Thistlethwaite (The Christie, Manchester),

Dr. Simon Lord (Oxford Univ.),

Dr. Dean Fennell (Univ. of Leicester),  

Dr. Peter Szlosarek (St. Barth's London)

Description: This is an open label, non-randomized translational phase 1/2 dose- escalation and expansion study to determine the safety, tolerability, maximum tolerated dose and/or recommended phase 2 dose, pharmacokinetics and pharmacodynamics of RSO- 021 after intrapleural administration in patients with MPE. Patients must also have received and progressed on at least 1 standard line of treatment. The study will also evaluate antitumor activity of RSO-021 in two separate expansioncohorts; (1) in patients with MPE (non-mesothelioma) and (2) in patients with MPE from mesothelioma (up to 42 patients total for both cohorts).

Read more about MITOPE

US NIH:  NCT05278975
Mesothelioma UK:



MITOPE management team at

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