The PRAME immunotherapeutic had an acceptable safety profile. All patients had anti-PRAME humoral responses that were not dose related, and 80% of those treated at the highest dose showed a cellular immune response. The dose of 500 μg was selected. However, further development was stopped after negative results with a similar immunotherapeutic in patients with NSCLC.

PurposeThe PRAME tumour antigen is expressed in several tumour types but in few normal adult tissues. A dose-escalation phase I/II study (NCT01149343) assessed the safety, immunogenicity and clinical activity of the PRAME immunotherapeutic (recombinant PRAME protein (recPRAME) with the AS15 immunostimulant) in patients with advanced melanoma. Here, we report the phase I dose-escalation study segment.Patients and methodsPatients with stage IV PRAME-positive melanoma were enrolled to 3 consecutive cohorts to receive up to 24 intramuscular injections of the PRAME immunotherapeutic. The RecPRAME dose was 20, 100 or 500 µg in cohorts 1, 2 and 3, respectively, with a fixed dose of AS15. Adverse events (AEs), including predefined dose-limiting toxicity (DLT) and the anti-PRAME humoral response (ELISA), were coprimary end points. Cellular immune responses were evaluated using in vitro assays.Results66 patients were treated (20, 24 and 22 in the respective cohorts). AEs considered by the investigator to be causally related were mostly grade 1 or 2 injection site symptoms, fatigue, chills, fever and headache. Two DLTs (grade 3 brain oedema and proteinuria) were recorded in two patients in two cohorts (cohorts 2 and 3). All patients had detectable anti-PRAME antibodies after four immunisations. Percentages of patients with predefined PRAME-specific-CD4+T-cell responses after four immunisations were similar in each cohort. No CD8+ T-cell responses were detected.ConclusionsThe PRAME immunotherapeutic had an acceptable safety profile and induced similar anti-PRAME-specific humoral and cellular immune responses in all cohorts. As per protocol, the phase II study segment was initiated to further evaluate the 500 µg PRAME immunotherapeutic dose.Trial registration numberNCT01149343, Results.

The objectives of this phase I/II study (NCT00140738) were to evaluate the safety and clinical activity of a cancer immunotherapeutic agent (recombinant HER2 protein (dHER2) and the immunostimulant AS15) in patients with HER2-overexpressing metastatic breast cancer (MBC). Forty HER2-positive MBC patients received up to 18 doses (12q2w, 6q3w) of dHER2 immunotherapeutic, as first- or second-line therapy following response to trastuzumab-based treatment as maintenance. Toxicity was graded by the Common Terminology Criteria for Adverse Events (CTCAE) and clinical activity was evaluated by target lesion assessment according to the Response Evaluation Criteria in Solid Tumors (RECIST). Immunogenicity was assessed. The dHER2 immunotherapeutic was well tolerated: grade 1/2 adverse events (AEs) were most common. No cardiac events were observed and one patient experienced an asymptomatic decrease of left ventricular ejection fraction below the normal range (47 %). Both humoral and cellular immunogenicity to the dHER2 antigen was observed. No patient discontinued the immunizations because of AEs but 35/40 withdrew prematurely, 34 because of disease progression (24/34 before or at the tumor assessment after dose 6). One patient achieved a complete response lasting 11 months and one patient had a partial response lasting 3.5 months. Ten patients experienced stable disease ≥26 weeks with 4/10 still in stable disease at the last tumor assessment after 47 weeks. Immunization of MBC patients with the dHER2 immunotherapeutic was associated with minimal toxicity and no cardiac events. Clinical activity was observed with two objective responses and prolonged stable disease for 10/40 patients.