Platinum anticancer drugs: mechanisms and resistance
Platinum anticancer drugs remain a benchmark in cancer treatment because their DNA-damaging activity can produce durable responses in several tumour types. Cisplatin, carboplatin and oxaliplatin share a strategy—entering cells, undergoing aquation and binding nuclear DNA—but differ in toxicities and sensitivity. The central challenge is resistance, both intrinsic and acquired during repeated exposure.
Cisplatin creates covalent DNA adducts, especially 1,2-intrastrand cross-links that distort the double helix. Replication stress, defective repair and futile mismatch-repair cycles can trigger apoptosis. Tumour cells evade this pathway by altering uptake or efflux, increasing glutathione and metallothionein, changing DNA-repair capacity, or tolerating lesions through translesion synthesis. These mechanisms make combinations and new platinum formulations active research priorities.
The 16th International Symposium on Applied Bioinorganic Chemistry, held in Ioannina, Greece in June 2023 and organised by the University of Ioannina, gathered developments across applied bioinorganic chemistry, from metal-based therapeutics to translational analytical methods. Its themes are relevant to Australian oncology teams, where platinum agents are routine in public cancer care and laboratory insight must still account for patient selection, dosing and quality of life.
Why platinum agents still matter
Australian public cancer systems in Sydney, Melbourne, Brisbane and Adelaide use platinum-based chemotherapy in protocols for testicular, gynaecological, bladder, lung and gastrointestinal cancers. Familiar treatments still require monitoring for nephrotoxicity, ototoxicity, myelosuppression and cumulative peripheral neuropathy.
Local care is shaped by a market combining PBS-listed medicines with hospital purchasing, so cost and supply do not fully explain treatment choice. Efficacy, prior therapy, renal function, hearing, neuropathy and patient goals remain central. Tumour boards benefit from evidence that distinguishes platinum sensitivity from resistance rather than treating the class as interchangeable.
From aquation to DNA damage
Inside the cell, cisplatin undergoes aquation: chloride ligands are replaced by water, creating electrophilic complexes that bind purine nitrogens. Monofunctional adducts can close into bifunctional cross-links, with lesions between adjacent guanines or between guanine and adenine being important.
These lesions distort DNA and impede replication and transcription. Stalled forks activate nucleotide excision repair, homologous recombination and the Fanconi anaemia pathway; ERCC1 and XRCC1 influence platinum-adduct removal. When damage persists, translesion synthesis permits lesion bypass, while apoptotic signalling determines survival.
Mismatch repair adds another layer. In mismatch-repair-proficient cells, recognition of cisplatin-induced distortions can provoke futile repair attempts and increase cytotoxicity. Oxaliplatin has a different adduct spectrum and is often more active in mismatch-repair-deficient colorectal cancers, showing why molecular context matters as much as drug name.
How platinum resistance emerges
Reduced uptake through the copper transporter CTR1, increased efflux and sequestration by glutathione or metallothionein can lower intracellular platinum. These changes may pre-exist in resistant clones. Hypoxia, nutrient conditions and tumour-microenvironment signals can alter repair and apoptosis, making resistance a property of the environment rather than a single gene.
Treatment then selects cells that tolerate adducts. Enhanced DNA repair, altered transport and greater survival signalling can establish acquired resistance. Tumour heterogeneity complicates assessment: a biopsy may miss a resistant subclone, while therapy changes the population represented by a later sample.
Cross-resistance is uneven. Carboplatin often shares cisplatin resistance, whereas oxaliplatin activity may persist because its adduct and repair profile differs. Models should therefore use the intended agent, relevant tumour genotype and realistic exposure schedules before a combination is advanced.
Comparing the principal platinum drugs
Choice among established agents is not simply a ranking of potency. Aquation kinetics, adduct chemistry, distribution and dose-limiting toxicities shape each clinical niche, while molecular and patient-specific factors modify that baseline.
| Platinum agent | Mechanistic signature | Main clinical constraint | Resistance distinction |
|---|---|---|---|
| Cisplatin | Aquated species; abundant 1,2-intrastrand cross-links | Nephrotoxicity and ototoxicity | Reduced uptake or repair capacity can sharply reduce activity |
| Carboplatin | Slower aquation; broadly similar DNA-adduct biology | Myelosuppression | Often cross-resistant to cisplatin; marrow reserve affects dosing |
| Oxaliplatin | Distinct adduct distribution and repair interactions | Peripheral neuropathy | Retains activity in some mismatch-repair-deficient colorectal cancers |
No agent is universally preferable. Renal impairment, neuropathy, hearing loss, blood counts, prior exposure and tumour site influence selection. These differences explain why preclinical comparisons cannot substitute for clinical evidence.
Biomarkers and rational combinations
Candidate biomarkers include ERCC1, mismatch-repair and microsatellite-instability status, CTR1 abundance, GST and ABC transporter activity, and assays quantifying platinum-DNA adducts. None should stand alone. Sampling variability, temporal changes and differences between biopsy and bulk tumour can weaken a single-marker strategy.
Combination studies explore platinum drugs with PARP inhibitors, immunotherapy, antifolates or delivery systems. The rationale must be specific: synthetic lethality in repair-deficient cells differs from immune activation, and neither guarantees benefit against broad platinum tolerance. Response and toxicity endpoints should be interpreted against the mechanism being tested.
International meetings help teams compare assay choices and translational priorities. For delegates comparing regional event calendars, AD14 Chile offers another meeting reference, while ISABC’s own programme concentrates on bioinorganic chemistry and its applications.
Translating findings for Australian teams
Australian laboratories can contribute analytical methods that measure intact adducts, repair activity and intracellular platinum, supported by cancer-research networks in Melbourne, Sydney, Brisbane and Perth. Reproducible protocols matter when centres use different sampling and storage procedures. Collaboration with hospital investigators can connect measurements directly to treatment response.
Regulated clinical materials and biological specimens require planning. Australian Border Force customs clearance, Therapeutic Goods Administration requirements and sponsor approvals may apply to imported reference materials; teams should check them before samples travel to Greece or enter Australia. They should also confirm whether a companion diagnostic is a research assay or part of an approved clinical workflow.
Practical arrangements matter. Australian delegates usually connect through Athens to reach Ioannina, with June bringing warm days and cooler evenings around the city’s lake and historic centre. The Ioannina symposium information provides local context for travel planning, while Zita Congress & Event Management is the official secretariat for registration, accommodation and abstract-related enquiries.
Turning mechanism into better outcomes
The next phase of platinum research should pair better chemistry with better selection. Linking adduct formation to DNA-repair competence, serial tumour sampling and patient-reported toxicity could identify where a new agent or combination adds meaningful benefit. Standardised models should distinguish innate tolerance from adaptations that emerge during therapy.
Researchers, clinicians and students can act by reviewing the official symposium website for the archived programme, participation guidance, application requirements, abstract materials, young-scientist travel awards, poster prizes and scholarship details. Teams seeking collaboration or information about a future edition should contact Zita Congress & Event Management regarding registration, accommodation and abstract-related enquiries, then share the findings with laboratories and oncology services across Australia.