NTX-301 Monotherapy in Advanced Solid Tumours and in Combination With Platinum-based Chemotherapy in Advanced Ovarian & Bladder Cancer and in Combination With Temozolomide in High-grade Glioma

Dose Exploration (Phase 1a, n\~25): This part of the study will assess the safety and tolerability of NTX-301 and to identify the Maximum Tolerated Dose (MTD) and Recommended Phase 2 Dose (RP2D). It will initiate with a dose escalation using a 3+3 design. Combination Dose and Disease Expansion (Phase 1b-2a, n\~60): The study will be expanded in specific subsets of patients with solid tumours and with combination therapy as follows: * Arm 1 (Phase 1b, n\~20): Dose Escalation, NTX-301 platinum-based doublet therapy * Arm 2 (Phase 2a, n\~40): Dose Expansion, NTX-301 platinum-based doublet therapy Patients with advanced ovarian \& bladder cancer considered to be incurable by the investigator and for which available anti-cancer therapy has been exhausted will be enrolled for this component. Patients will be given NTX-301 at the MTD determined in Phase 1a. This will be combined with a platinum-based agent that will be administered by IV infusion. Optional Cohort -High-Grade Glioma Combination Dose \& Disease Expansion (Phase 1b-2a, n\~40) * Arm 3 (Phase 1b, n\~20): Dose Escalation, NTX-301 combination therapy with TMZ * Arm 4 (Phase 2a, n\~20): Dose Expansion, NTX-301 combination therapy with TMZ Patients with IDH1 mutated high-grade glioma that have commenced initial chemoradiotherapy with temozolomide and are yet to commence Temozolomide maintenance therapy will be enrolled for this component. Patients will be given NTX-301 at the MTD determined in Phase 1a. This will be combined with TMZ that will be administered orally.