Citius Pharmaceuticals has entered a clinical partnership with the University of Pittsburgh for a Phase I/Ib trial of I/ONTAK (denileukin diftitox or E7777) plus pembrolizumab to treat recurrent or metastatic solid tumours.

The open-label, investigator-initiated trial will assess T-reg cell depletion on administering I/ONTAK along with pembrolizumab in such patients. 

It will have two parts. The Part I dose escalation trial will have four cohorts assessing three, six, nine, and 12mcg doses of I/ONTAK and will enrol 18-30 subjects. 

The Part II dose expansion trial will enrol nearly 40 subjects to assess the safety and tolerability of the recommended combination dosage of I/ONTAK plus pembrolizumab. 

The trial will also evaluate the variation in the immune microenvironment within tumours, as well as in the peripheral blood. 

Objective response (complete response plus partial response), overall survival, and progression-free survival will be the trial’s secondary endpoints.

The University of Pittsburgh trial is anticipated to commence in the fourth quarter of this year.

The company is also partnering with a Phase I investigator-initiated trial at the University of Minnesota (UMN). 

This dose-finding trial is analysing I/ONTAK administered before tisagenleucel (KYMRIAH) CAR-T therapy in diffuse large B-cell lymphoma (DLBCL) patients. 

The first patient in the study was enrolled in May last year.

A recombinant fusion protein, I/ONTAK merges the interleukin-2 (IL-2) receptor binding domain and diphtheria toxin fragments. 

Pembrolizumab is a PD-1 checkpoint inhibitor. 

Citius Pharmaceuticals chief medical officer Dr Myron Czuczman said: “Preclinical research in a syngeneic solid tumour mouse model shows that E7777 [denileukin diftitox] enhances anti-tumour activity and significantly extends the survival benefit of anti-PD-1 therapy. 

“This data provides a positive signal of denileukin diftitox’s potential in the immuno-oncology space.”

In May this year, the company selected clinical research organisation Biorasi to aid in expanding its Phase III Mino-Lok trial of a new antibiotic lock therapy to further sites outside the US.

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