Acquired resistance to every therapy
Nearly every targeted therapy stops working within months to a few years as the tumour adapts.
Every class of anticancer drug is followed by a catalogue of resistance mechanisms: on-target mutations (EGFR C797S, ESR1, BTK C481S, androgen receptor variants), bypass signalling (MET amplification, PI3K activation), lineage plasticity (adenocarcinoma to small-cell or neuroendocrine transformation), drug efflux, antigen loss after CAR-T or ADC therapy, and payload-specific resistance to topoisomerase inhibitors. Even the best first-line targeted therapies in lung cancer produce median progression-free survival of under two years. Because resistance biopsies are rare and mechanisms are heterogeneous between lesions, the choice of next-line therapy is often guesswork, and combination or sequencing strategies designed to pre-empt resistance are seldom tested prospectively. Degraders that remove the target, dual-payload conjugates, ctDNA-triggered switching, and upfront combinations are the emerging countermeasures.
- Tumours are heterogeneous, so a resistant subclone almost always pre-exists the drug.
- Single-agent targeting of one node leaves parallel pathways available for bypass.
- Resistance biopsies are uncommon outside academic centres, so mechanisms are inferred rather than measured.
- Sequential single-agent development is commercially simpler than testing rational upfront combinations.
- Lineage plasticity and epigenetic state changes are not captured by DNA sequencing and have few druggable handles.
- SERENA-6 established ctDNA-triggered switching to camizestrant on emergence of ESR1 mutation, before progression, as a viable strategy.
- Combinations such as amivantamab plus lazertinib (MARIPOSA) and osimertinib plus chemotherapy (FLAURA2) attack EGFR resistance up front.
- BTK degraders (BGB-16673) and non-covalent BTK inhibitors (pirtobrutinib) are designed to work after covalent-inhibitor resistance and to pre-empt it in first line.
- Dual-payload and bispecific ADCs (Sutro Biopharma, Mersana, SystImmune's BL-B01D1) aim to prevent payload- or antigen-loss resistance.
- AACR Project GENIE and cBioPortal make paired pre- and post-resistance sequencing data available for pooled analysis.
- Evolutionary and adaptive therapy trials at Moffitt test dosing schedules that maintain drug-sensitive clones to suppress resistant ones.
Blood tests can already detect tumour DNA. Reporting which sub-populations of the tumour are growing or shrinking, cycle by cycle, would turn the test into an evolution monitor.
Sometimes a progression biopsy shows exactly which drug would help, but it is licensed for another cancer and cannot be obtained. A standing pathway would fix that.
Instead of a new trial for each resistance mechanism, one continuous trial could sort patients into arms based on the reason their last treatment failed.
For each cancer-causing mutation, find every gene the cancer cell newly depends on, in every tissue, so that even undruggable drivers get druggable partners.
When a resistance mutation first appears in the blood, the current drug is often still controlling most of the tumour. Adding a second drug rather than swapping may keep both under control.
If most tumours escape a drug by the same back-up route, blocking that route from the start may prevent resistance rather than chase it.
When a tumour evolves resistance to one drug, it sometimes becomes weaker against another. Map these trade-offs systematically so doctors can pick the next drug to exploit them.
Rather than giving the same dose until the cancer grows, measure tumour DNA in blood every few weeks and let a validated algorithm raise, lower, pause or switch drugs to keep the cancer suppressed for longer.
When a scan shows most tumours shrinking but one growing, that odd lesion holds the escape mechanism. Sampling it, and treating it locally, should be routine.
Cells that survive treatment do so by changing which genes they use, not their DNA. Drugs that block that change may stop survivors from forming at all.
Cancer cells can survive a drug because surrounding normal cells feed them growth signals. Blocking those signals could make existing drugs work better and longer.
Some tumours have broken the machinery that displays their identity to immune cells. Those patients cannot benefit from most immunotherapy and should be routed elsewhere.
Treatment leaves behind damaged cells that stop dividing but do not die, and they release signals that help surviving cancer cells regrow. Removing them could reduce relapse.
Group patients by why their last drug stopped working, then test the combination designed to fix that specific failure, whatever the cancer.
Use tumour DNA in the blood as the signal to pause and restart a lung cancer pill, keeping the tumour in check while slowing the rise of resistant cells.
When attacked, cells switch on a survival programme that buys them time to adapt. Blocking that programme could turn a partial response into a complete one.
Choose two treatments so that whatever the tumour does to escape the first, it becomes easier to kill with the second. The immune system is a good candidate partner.
In advanced prostate cancer, a shortened form of the hormone receptor loses the very part existing drugs bind to. A drug that destroys the whole protein would still work.
Some cancers escape treatment by changing into a different kind of cell that the drug no longer affects. Tumour RNA in blood could show this shift months before a biopsy would.
When doctors discover how a tumour escaped a drug, that finding usually stops at a paper. Recreating it in a model gives everyone a system to test the next drug against.
Rather than hitting the tumour as hard as possible, adaptive therapy uses just enough drug to keep it in check, letting drug-sensitive cells suppress resistant ones. A small prostate cancer pilot was promising; randomised trials are needed.
Cells that receive only a small amount of a drug survive and adapt. Measuring where inside a tumour the drug actually reaches would show where resistance is being bred.
Flu vaccines are chosen by predicting which virus strains will dominate next season. The same forecasting maths could predict which resistance mutation a patient's tumour will develop next.
When a treatment stops working, the tumour is rarely re-sampled, so nobody learns why. Paying for a biopsy at that moment would build the missing map of resistance.
Some patients cannot have their tumour biopsied safely. Cancer cells captured from a blood sample can sometimes be grown into a model instead.
A few cancer cells survive treatment by going quiet rather than mutating. These survivors are unusually vulnerable to a particular kind of cell death, which a drug could trigger.
Resistance mutations often exist in a tiny fraction of cells before treatment starts. A very sensitive test at diagnosis could find them and prompt a combination from day one.
Drugs approved on early evidence come with follow-up obligations. One of them should be finding out how tumours escape the new drug.
Knowledge about how cancers become resistant is scattered across thousands of papers and company files. Pooling it into one structured, public resource would let anyone see the pattern.
Resistant cancer cells sometimes come to depend on the very drug they resisted. Stopping the drug for a while can make them vulnerable to it once more.
Cell therapies fail when the tumour stops showing the marker they were built to find. Preparing an alternative product in advance would let doctors switch quickly.
Trials usually study one treatment at a time, so nobody knows the best order. Deciding the next step in advance, by lottery, answers the sequencing question at little extra cost.
Antibody drugs need their target to still be present. After one fails, checking which surface markers remain would guide the choice of the next one instead of guessing.
Treatment is often chosen from a biopsy taken years earlier from the original tumour. The spread disease may now look different. Test it again before switching drugs.
Hospitals rotate antibiotics to stop bacteria adapting. Cycling between two cancer drugs on a set schedule, rather than using one until it fails, might work the same way.
Patients are randomised at each decision point, not just at the start, so one trial can compare whole treatment sequences rather than single drugs.
Many tumours carry an enzyme that keeps creating new mutations, feeding resistance. Blocking that enzyme while a targeted drug works could make resistance arrive later.
Real treatment is a series of decisions: start with this, switch to that if it fails. Sequential multiple-assignment randomised trials test whole strategies by randomising patients again at each decision point.
Cells that survive treatment often change how they make energy, relying on burning fat rather than sugar. Blocking that switch might finish them off.
Species go extinct when a second disaster hits a population already shrunk by a first one. Apply the same logic: hit the tumour with a different kind of drug when it is smallest, rather than waiting for it to grow back.
Two drugs might work better given in turns rather than together, with less toxicity. Almost no trial has tested this.
Giving a targeted drug in pulses rather than continuously might slow the emergence of resistant cells and reduce side effects. Early results are mixed, so this needs careful trials with clear rules for when to try it.
Targeted drugs briefly make cancer cells easier for the immune system to spot. Giving immunotherapy exactly in that window, rather than at the same time, may work better.
Countries track how bacteria become resistant to antibiotics and publish it. Doing the same for cancer drugs would show which escape routes are becoming common and where.
Under treatment stress, cancer cells switch on sloppy DNA copying that generates the mutations they need to survive. Blocking that machinery could stop resistance being invented.
If a drug relies on one marker, the tumour can survive by dropping it. A drug that recognises two markers at once makes that escape harder.
A single protein predicts whether a tumour will respond to DNA-damaging drug payloads. Measuring it could stop patients receiving a second drug of the same kind that will not work.
Resistance often arrives as the same few mutations. Teaching the immune system to recognise them in advance could remove the escaping cells while they are still rare.
Cancers with faulty DNA proof-reading depend on one particular unwinding enzyme to survive. Blocking it kills them and spares normal cells.
Patients with newly diagnosed metastatic colorectal cancer whose tumour carries a BRAF V600E mutation, which is about 8-12% of cases, should now be offered encorafenib and cetuximab together with FOLFOX from the start rather than after chemotherapy fails; median survival has roughly doubled to about two and a half years. BRAF testing at diagnosis is therefore essential, alongside RAS and mismatch repair testing. The regimen is more toxic than chemotherapy alone.
Patients newly diagnosed with EGFR-mutated advanced lung cancer now have a first-line option that improves survival over osimertinib, particularly if they have high-risk features. The trade-off is intravenous (now subcutaneous) infusions and considerably more skin, nail and clotting toxicity, so osimertinib alone remains reasonable for those who prioritise convenience and tolerability. Both this regimen and osimertinib plus chemotherapy (FLAURA2) are approved; there is no direct comparison.
Revumenib proved that a transcriptional dependency, rather than a kinase, can be drugged in leukaemia, opening treatment for two genetic subgroups that together cover roughly a third of AML plus most infant ALL. It is now approved and is being combined with venetoclax-azacitidine and intensive chemotherapy in front-line trials. Single-agent remissions are often short without transplant.
Patients with KRAS G12C lung cancer that has progressed after chemo-immunotherapy can take an oral KRAS inhibitor instead of docetaxel and gain a somewhat longer time to progression with fewer severe side effects, but should understand that most tumours become resistant within a year and that survival is not improved. KRAS G12C testing is worthwhile, but first-generation inhibitors are a step rather than a cure; combinations and next-generation inhibitors are the active research fronts.
Patients with metastatic colorectal cancer carrying a KRAS G12C mutation (about 3-4% of cases) who have exhausted standard chemotherapy now have a targeted option that works far better than trifluridine-tipiracil or regorafenib. The higher sotorasib dose is clearly superior, and the EGFR antibody is essential because KRAS inhibition alone barely works in bowel cancer. Responses are still modest and short-lived compared with EGFR or ALK inhibitors in lung cancer.
CD20 x CD3 bispecifics gave patients whose lymphoma has failed CAR-T, or who cannot access it, an effective off-the-shelf treatment that can be started within days. Epcoritamab and glofitamab are now standard third-line options and are moving into earlier lines and combinations. They do not yet replace CAR-T, whose remissions appear more durable.
QuANTUM-First gave FLT3-ITD AML patients a second front-line targeted option and showed that continuing a FLT3 inhibitor as long-term maintenance, including after transplant, pays off. Quizartinib was approved for this indication in 2023. Head-to-head data against midostaurin are lacking, and the design leaves open how much of the benefit came from maintenance.
For HER2-positive metastatic breast cancer that has progressed after trastuzumab and a taxane, trastuzumab deruxtecan is now the standard second-line treatment and T-DM1 has moved later in the sequence. The benefit is large enough that ADC design, not just the target, is understood to be what matters. Patients need lung monitoring because of the risk of pneumonitis.
Cancer is now understood to change its identity and behaviour without new mutations, to be shaped by bacteria inside and around it, and to be helped along by ageing cells. This explains why some tumours escape targeted drugs by changing cell type and why gut bacteria affect immunotherapy response.
Sacituzumab govitecan is a standard second-line or later treatment for metastatic triple-negative breast cancer, roughly doubling survival compared with the chemotherapies it was tested against. Patients should expect neutropenia and diarrhoea, which are manageable with growth factor support and loperamide. Trials are now testing it earlier, in first-line combinations with pembrolizumab and after surgery for residual disease.
For ALK-positive advanced lung cancer, lorlatinib as the first drug offers the possibility of many years without progression and strong protection against brain metastases. Alectinib and brigatinib remain alternatives with a gentler side-effect profile; the choice weighs lorlatinib's cognitive, metabolic and weight effects against its unmatched duration of control.
The UCART19 report was the first clinical evidence that a universal, pre-manufactured CAR-T made from a donor can work, avoiding the weeks of autologous manufacturing and the problem of patients whose own T cells are too damaged. It set the template for later allogeneic programmes (including cemacabtagene autoleucel in the ALPHA studies) and for in vivo CAR generation. Short persistence and the need for deep lymphodepletion remain the central weaknesses.
VIALE-A turned a palliative regimen into one that produces remission in two-thirds of older AML patients and is now the reference treatment for anyone not fit for intensive chemotherapy. It shifted the field towards lower-intensity targeted combinations and opened the door to adding FLT3, IDH and menin inhibitors to the backbone. Cure remains uncommon and most patients relapse within two years.
ZUMA-2 gave patients with BTK-inhibitor-refractory mantle cell lymphoma, who previously had a median survival under a year, a therapy with durable remissions in a substantial fraction. Brexu-cel is now standard after BTK inhibitor failure and CAR-T is being tested earlier in the disease. Neurotoxicity rates are higher than in other lymphoma CAR-T trials.
ADMIRAL showed that a targeted oral drug can beat chemotherapy outright in relapsed AML, and made gilteritinib the standard bridge to transplant for FLT3-mutated relapse. Its success also underpinned FLT3 inhibitor use in first-line combinations. Resistance through FLT3-independent clones and RAS pathway mutations limits durability without transplant.
Anyone diagnosed with advanced lung cancer should have EGFR testing before treatment, because osimertinib as the first drug gives the longest disease control, protects the brain, and is well tolerated. Chemotherapy is not the first step for these patients. The remaining questions are whether to intensify upfront (adding chemotherapy or amivantamab) and how to treat resistance when it develops.
MURANO made fixed-duration venetoclax the standard for relapsed CLL and showed that stopping therapy after a deep response is safe for most patients. It also established MRD at end of treatment as a practical guide to who is likely to stay in remission. Retreatment with venetoclax at relapse appears feasible.
Every woman diagnosed with advanced high-grade ovarian cancer should be tested for BRCA mutations at diagnosis, because those who carry one should receive two years of olaparib after chemotherapy, which greatly extends the time in remission and improves long-term survival. The plateau in the survival curves suggests some patients are cured by this approach. Toxicity is mostly anaemia, fatigue and nausea, and the two-year limit appears sufficient.
Lung cancers keep evolving after they form, and it is ongoing chromosomal instability rather than the number of mutations that best predicts who will relapse. This gives a rationale for targeting the earliest (clonal) drivers and neoantigens and for tracking evolution in blood after surgery.
The most frequently mutated oncogene in cancer stopped being undruggable, and patients with KRAS G12C lung and bowel cancers now have targeted pills. The approach, exploiting a mutation-created chemical handle and an inactive-state pocket, has become a template for other hard targets.
A single biopsy is an incomplete picture of a patient's cancer. Truncal mutations shared by all cells (in kidney cancer, VHL) are the most reliable drug targets, whereas mutations in only some branches predict resistance. This is why liquid biopsy and multi-region sampling matter.
Instead of blocking a cancer protein, a drug can now remove it entirely, which works even for proteins without a druggable active site and can overcome resistance driven by target overexpression or mutation. Several degraders are in late-stage trials for breast and prostate cancer.
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not linked directly; found by shared links- BottleneckTumour heterogeneity and clonal evolution
Shares Slow the tumour's mutation engine with APOBEC inhibitors during targeted therapy, Switch drugs at maximum response, not at relapse, An open atlas of collateral sensitivity for every approved targeted drug, Find the parts of a tumour the drug never reaches.
- TargetEGFR
Shares Vaccinate against the resistance mutation before it takes over, Add a drug when the blood test turns, without stopping the one that works, ctDNA-guided dose holidays for lung cancer targeted therapy, EGFR C797S.
- BottleneckToo many combinations to test
Shares Rotate between drugs on a fixed schedule instead of waiting for failure, Test alternating drug schedules against giving both drugs at once, An open atlas of collateral sensitivity for every approved targeted drug, Combination baskets defined by resistance mechanism rather than by cancer type.
- TargetMET
Shares Block the survival signals the tumour's neighbours provide, Add a drug when the blood test turns, without stopping the one that works, MET amplification (bypass resistance), Add the second drug on day one when the escape route is predictable.
- TermCirculating tumour DNA (ctDNA)
Shares Fund a biopsy at progression, every time, as standard care, SMART designs to test treatment strategies, not just single drugs, ctDNA-guided dose holidays for lung cancer targeted therapy, Test intermittent dosing of targeted drugs to delay resistance, with honest priors.
- TechnologyAntibody-drug conjugate (ADC)
Shares Two-target antibody drugs to close the antigen escape route, ADC payload neutralisers, Combination baskets defined by resistance mechanism rather than by cancer type, Mersana Therapeutics.
- TargetBTK (Bruton tyrosine kinase)
Shares BRUIN CLL-321, CaDAnCe-304, BTK degraders to pre-empt resistance in frontline CLL, BGB-16673.
- TermOverall survival (OS)
Shares Randomise the next line of treatment before the first one fails, ADMIRAL: gilteritinib pills versus chemotherapy for relapsed FLT3-mutated acute myeloid leukaemia, QuANTUM-First: quizartinib added to intensive chemotherapy and continued as maintenance in newly diagnosed FLT3-ITD AML, VIALE-A: venetoclax plus azacitidine for older adults with acute myeloid leukaemia who cannot have intensive chemotherapy.