Dose escalation will be guided by a Bayesian logistic regression model with overdose control. Once MTD/ RP2D is declared, patients will be enrolled in the phase II part in the selected indications (glioblastoma, pancreatic cancer and triple negative breast cancer) to further assess the preliminary anti-tumor activity of BLZ945 in combination with PDR001. Should signs of anti-tumor activity be seen in the phase I dose escalation with BLZ945 as single agent, a phase II part will be opened in order to further explore BLZ945 single agent efficacy at the recommended dose.