A Study of PRS-344/S095012 (PD-L1x4-1BB Bispecific Antibody) in Patients With Solid Tumors

A First in Human Phase 1-2 Open-Label, Multicenter, Dose Escalation and Expansion Study of PRS-344/S095012 in Patients With Solid Tumors

This is a first-in-human (FIH), phase 1/2, multi center, open-label, dose escalation and cohort expansion study designed to determine the safety and tolerability of PRS-344/S095012 in patients with advanced and/or metastatic solid tumors.

The trial is an open-label, multi-center safety trial of PRS-344/S095012. The trial consists of two parts, a dose escalation part (phase 1, first-in-human (FIH) and an expansion part (phase 2)). The expansion part of the trial will be initiated once the optimal biological dose (OBD) has been determined. The study was terminated during phase 1 and thus, recruitment into phase 2 was not started.

Inclusion Criteria:

1. Age ≥18 years on the day the consent is signed.
2. Patients with histologically confirmed diagnosis of unresectable, locally advanced or metastatic solid tumor for which standard treatment options are not available, no longer effective, or not tolerated.
3. Patient should have a documented disease progression on prior therapy before entry into this study.
4. Patients must have at least one measurable target lesion as per RECIST 1.1.
5. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
6. Patient with no available archived material must have one or more tumor lesions amenable to biopsy.
7. Adequate organ function as assessed by laboratory tests within 7 days prior to pretreatment with obinutuzumab.
8. A female patient must use a highly effective method of birth control during study treatment and for 120 days after last dose of PRS-344/S095012, or 18 months after the last obinutuzumab infusion, whichever comes the latest.

Exclusion Criteria:

1. Patients with previously treated brain metastases may participate provided they are radiologically stable, clinically asymptomatic and are off immunosuppressive therapies for at least 4 weeks. Low dose of steroid <10 mg/day prednisone or equivalent) is allowed.

2. Patients who have received prior:

   1. Small molecule inhibitors, and/or other similar investigational agent: ≤ 2 weeks or 5 half-lives, whichever is shorter.
   2. Chemotherapy, other monoclonal antibodies, antibody-drug conjugates, or other similar experimental therapies: ≤3 weeks or 5 half-lives, whichever is shorter.
   3. Radioimmunoconjugates or other similar experimental therapies ≤6 weeks or 5 half-lives, whichever is shorter.

3. Patients who have received 4-1BB agonists in the past.

4. Patients who had a major surgery within 4 weeks prior to first administration of IMP.

5. History of progressive multifocal leukoencephalopathy.

6. Active tuberculosis requiring treatment within 3 years prior to the start of treatment or a suspicion of latent tuberculosis by the investigator.