ADC Therapeutics has dosed the first patient with camidanlumab tesirine (Cami, formerly ADCT-301) in combination with pembrolizumab in an ongoing Phase Ib trial evaluating the drug in patients with selected advanced solid tumours.

Camidanlumab tesirine is an antibody drug conjugate with a monoclonal antibody that attaches to CD25, conjugated to the pyrrolobenzodiazepine dimer payload, tesirine.

CD25 is expressed on regulatory T cells (Tregs) that infiltrate the local tumour microenvironment.

The ongoing, multi-centre, open-label, dose-escalation and dose-expansion Phase Ib trial is analysing the safety, tolerability, pharmacokinetics and anti-tumour activity of Cami as a monotherapy or in combination with pembrolizumab, a checkpoint inhibitor.

The trial will enrol approximately 95 patients. It will have a screening period of 21 days, a treatment period with cycles of three weeks, and a follow-up period for up to a year after treatment discontinuation.

ADC Therapeutics senior vice-president and chief medical officer Jay Feingold said: “We are pleased to have dosed our first patient in an additional arm of our Phase Ib trial of Cami in solid tumours, which is intended to identify an appropriate dosing regimen for Cami in combination with pembrolizumab and detect signals of clinical activity in expansion cohorts using the identified dosing regimen.

“We look forward to the continued evaluation of our CD25-targeted ADC, as monotherapy and in combination with a checkpoint inhibitor, as a novel immuno-oncology approach for the treatment of solid tumour cancers.”

Data from the preclinical models showed that a single dose of the drug induced strong and durable anti-tumour activity against established CD25-negative solid tumours with infiltrating Tregs, both as a monotherapy and with a checkpoint inhibitor.

Cami is currently evaluated in a pivotal Phase II trial in patients with relapsed or refractory Hodgkin lymphoma (HL).