Minimal / molecular residual disease (MRD)
Cancer still present after treatment but too small to see on scans, detected by blood or marrow tests.
In leukaemia/myeloma: flow cytometry or NGS of marrow (clonoSEQ). In solid tumours: ctDNA after surgery. MRD positivity predicts relapse; MRD-guided escalation (IMvigor011) and de-escalation (DYNAMIC) are proven concepts; MRD is an accepted endpoint in myeloma trials (FDA ODAC 2024).
AMPLIFY delivered the first all-oral, fixed-duration doublet for front-line CLL and supported its approval, giving fit patients a way to avoid both chemotherapy and years of continuous BTK inhibitor. It does not settle whether a doublet or triplet is best, or how AV compares with venetoclax-obinutuzumab. Patients with TP53 aberration were excluded and still need different strategies.
AALL1731 brings immunotherapy into the front-line treatment of the commonest childhood cancer, in the group of children where most relapses were occurring despite good initial risk. Blinatumomab was approved for this use in 2024 and paediatric protocols worldwide are being amended. Whether it can allow less chemotherapy, and its effect on very low-risk children, are the next questions.
After bladder removal, a blood test can now tell who needs immunotherapy and who can safely be spared it. This is the model for MRD-guided adjuvant therapy across cancers: treat the blood-positive, watch the blood-negative.
E1910 changed the standard of care for adult B-ALL: immunotherapy is now part of front-line consolidation even for patients with no detectable leukaemia, because MRD-negative by flow cytometry does not mean cured. It also demonstrated that a T-cell engager can improve overall survival in a curative setting. Chemotherapy-light or chemotherapy-free regimens built on blinatumomab and inotuzumab are the next step.
The blood test stratifies risk far better than stage or pathology. It supports treating ctDNA-positive patients and suggests ctDNA-negative patients gain little from chemotherapy, but because treatment was not randomised the de-escalation claim needs the randomised trials that are now under way.
Relapse after surgery is driven by particular subclones that can be identified in the primary tumour and tracked in blood, which argues for evolution-aware adjuvant strategies. The pollution finding reframes carcinogenesis: some agents promote already-mutant cells rather than causing mutations.
For stage II colon cancer, where most patients are cured by surgery alone, a blood test can identify the minority who benefit from chemotherapy and spare everyone else its side effects. It does not yet prove that treating ctDNA-positive patients improves survival compared with not treating them.
Every resected non-squamous lung cancer should be tested for EGFR mutations, because patients who carry one live longer if they take osimertinib for three years after surgery. The trial does not tell us whether adjuvant chemotherapy can be omitted, nor what happens on relapse after osimertinib, and the three-year duration was chosen empirically.
CLL14 established the first chemotherapy-free, fixed-duration regimen for front-line CLL and made MRD-guided thinking mainstream in the disease. Patients get a year of treatment and then a treatment-free period rather than indefinite therapy. The choice today is between fixed-duration venetoclax combinations and continuous BTK inhibitors, with no proven survival difference.
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.
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.
INO-VATE made inotuzumab a standard salvage therapy for adult ALL and a common route to transplant, and, with the TOWER trial of blinatumomab, moved adult ALL from chemotherapy-only salvage to immunotherapy. Both drugs have since been pulled into front-line regimens. The liver toxicity signal shaped how transplant conditioning is chosen after inotuzumab.