24 October 2014 - 24 October 2014 - US cancer immunotherapies developer Aduro BioTech Inc disclosed yesterday the presentation of updated safety and efficacy findings from a Phase Ib study, currently underway, of its novel immunotherapy CRS-207 plus standard chemotherapy in patients with unresectable malignant pleural mesothelioma (MPM).

CRS-207, built on Aduro's live-attenuated, double-deleted (LADD) Listeria monocytogenes immunotherapy platform, has been designed to trigger a potent innate immune response, in addition to an adaptive immune response targeting mesothelin, an antigen over-expressed in MPM tumors.

The Phase Ib trial, with 23 patients recruited so far, is a multi-center study including patients with unresectable MPM who are chemotherapy-naïve, have good performance status (ECOG 0 or 1) and adequate organ function. According to the study's design, patients get two prime vaccinations with CRS-207 two weeks apart, followed by up to six cycles of standard of care pemetrexed and cisplatin chemotherapy three weeks apart and then two CRS-207 boost vaccinations three weeks apart. Clinically stable patients are eligible to get CRS-207 maintenance vaccinations every eight weeks. Patients are followed every eight weeks until disease progression. Objectives of the study are to assess safety, immunogenicity, objective tumor responses and tumor marker kinetics. Additional response, follow-up and immune response data are pending.

The presentation was delivered at the International Mesothelioma Interest Group (iMig) Conference held in Cape Town, South Africa.

Out of 16 evaluable patients with response data, 75% (12/16) achieved confirmed durable partial responses (PR) and 19% (3/16) had stable disease (SD) after CRS-207 plus chemotherapy, for a 94% rate of disease control (PR and SD). At the time of the presentation, estimated progression-free survival was 7.5 months with one patient on study for more than 19 months, currently getting maintenance therapy with CRS-207 following the combo therapy.

Dirk G. Brockstedt, senior VP of R&D at Aduro, said his company's intends to further assess CRS-207 plus chemotherapy in a randomised, controlled Phase II study in mesothelioma, expected to start in H1 2015.