ASCO 2027: A Clinical Data Planner for Biomarker & CDx Teams
Research meetings show you where the biology is heading. Clinical meetings show you which biomarkers are about to become labels. For a diagnostics company, a CRO or a pharma biomarker team, that second question is the one that moves budgets: a single phase III readout can create a new tested population, redraw a cut-off, or make an assay you have spent years validating less relevant overnight.
This planner uses ASCO 2027, the largest clinical oncology meeting of the year, as the anchor for early summer, but the method applies to any late-stage readout. It covers how to read clinical data for biomarker implications, which results change companion diagnostic (CDx) strategy, how each team should prepare and what to do afterwards.
Key takeaways
- Late-stage clinical readouts matter to biomarker teams because they decide which populations, assays and cut-offs end up in labels and guidelines.
- Before acting on a biomarker result, check four things: whether the biomarker population was pre-specified, which assay and scoring system was used, where the cut-off sits, and how many patients had an evaluable sample.
- Four kinds of readout change CDx strategy: label-enabling trials in a biomarker-defined population, new indications created by redrawing an existing biomarker, label narrowing by biomarker, and ctDNA-guided trial designs.
- Diagnostics, CRO and pharma biomarker teams need different preparation, and most of the value comes from the follow-up: label watch, guideline updates and partnering conversations.
- The June data season sits between focused summits: ImmunoMark San Diego (10–11 February 2027) and London (3–4 March 2027) come earlier, and ImmunoMark Boston is in June 2027.
When and where: the 2027 meeting at a glance
The ASCO Annual Meeting 2027 runs from 4 to 8 June 2027 in Chicago, according to the organiser’s published dates. Last year’s meeting (ASCO 2026) ran from 29 May to 2 June 2026, also in Chicago. Confirm deadlines on the organiser’s site.
Why clinical data needs a different reading from research data
Our planner for the spring research meeting season focuses on science themes. Clinical data differs in three ways. The assay is fixed: by phase III the sponsor has chosen a test, scoring system and cut-off, so the data is evidence for that combination, not the biomarker in general. The statistics decide the label: a striking subgroup curve is not a pre-specified, alpha-controlled analysis. The consequences are commercial: a positive biomarker-defined readout starts the clock on CDx submissions, laboratory adoption, reimbursement and guideline changes.
How to read a late-stage readout for biomarker implications
Ask the same four questions of every relevant abstract, presentation or simultaneous publication. They separate results that will change practice from results that will only generate discussion.
1. Was the biomarker population pre-specified?
Was the biomarker-defined group a primary or key secondary endpoint in the testing hierarchy, a pre-specified subgroup without alpha, or a post hoc analysis? Usually only the first can support a biomarker-restricted indication alone. Untested pre-specified subgroups are supportive; exploratory cuts are hypotheses, however clean the forest plot.
2. Which assay, scoring system and cut-off?
PD-L1 is the familiar example: several immunohistochemistry assays, paired with different drugs and scored as tumour proportion score (TPS), combined positive score (CPS) or immune cell area at different thresholds. Our PD-L1 guide covers why these are not interchangeable. Note whether the trial used a central laboratory, a clinical trial assay that will become the CDx, or local testing.
3. Who was tested, and who was missing?
Check the evaluable sample rate, biomarker prevalence among screened patients, and whether tissue or plasma was used. A low evaluable rate signals a pre-analytical problem that will reappear in routine practice; prevalence tells you how many tests each eligible patient will cost.
4. Does the effect hold across the range of the biomarker?
Benefit concentrated at the high end of a continuous biomarker, with little below a threshold, warns that the label may later be narrowed, as happened in gastric cancer (below).
| Question | What to look for | Why it matters for CDx |
| Pre-specified or exploratory? | Testing hierarchy, alpha allocation, stratification factors | Decides whether a biomarker-restricted label is likely |
| Which assay? | Antibody or panel, platform, central or local testing | Identifies the likely CDx and any bridging study needed |
| Which cut-off? | Score type, threshold, how it was chosen | Sets the tested population and the scoring burden on labs |
| Evaluable rate and prevalence | Screened vs enrolled, tissue vs plasma, failure rate | Predicts testing volume and pre-analytical risk in practice |
| Effect across the range | Results by biomarker level, not just above and below the cut-off | Signals future label narrowing or expansion |
Which readouts change CDx strategy
Four kinds of result are worth stopping for.
Label-enabling trials in a biomarker-defined population
When a phase III trial meets its primary endpoint in a pre-specified biomarker population tested with a defined assay, a CDx submission usually follows alongside the drug filing. The practical questions: is the clinical trial assay the final device, is a companion or complementary claim more likely, and which laboratories will offer the test at launch? Our guide to companion vs complementary diagnostics explains how that choice is made.
New indications created by redrawing an existing biomarker
HER2-low breast cancer is the clearest recent case. In August 2022 the FDA approved trastuzumab deruxtecan for unresectable or metastatic HER2-low breast cancer on the basis of the DESTINY-Breast04 trial, and the existing VENTANA HER2 (4B5) assay was then approved to identify HER2-low patients. The biomarker was decades old, but tumours previously reported as HER2-negative became a treatable group, and pathologists had to score reliably at the low end of the immunohistochemistry scale. Readouts like this create demand for training, proficiency testing, digital pathology support and re-testing of archived samples.
Label narrowing by biomarker
Readouts also feed regulatory decisions after approval. In September 2024 an FDA advisory committee voted that the benefit-risk of first-line PD-1 inhibitors in HER2-negative, microsatellite-stable gastric and gastro-oesophageal junction adenocarcinoma was not favourable for tumours with PD-L1 expression below 1, and in 2025 the relevant indications were limited to PD-L1-positive disease. Long-term follow-up and pooled subgroup analyses can turn an all-comers indication into a tested one.
ctDNA-guided trial designs
Circulating tumour DNA is moving from exploratory endpoint into trial design. The randomised DYNAMIC trial in stage II colon cancer (New England Journal of Medicine, 2022) showed that a ctDNA-guided approach reduced adjuvant chemotherapy use without compromising recurrence-free survival. In advanced breast cancer, the phase III SERENA-6 trial used serial ctDNA monitoring to detect emerging ESR1 mutations and switch therapy before radiographic progression; an April 2026 FDA advisory committee voted against the switch strategy, but the FDA granted accelerated approval to camizestrant with a CDK4/6 inhibitor on 4 September 2026 for ESR1-mutated disease, with confirmatory trials required (FDA). It is the clearest example yet of a ctDNA-triggered treatment switch reaching a US label. The lesson for MRD and liquid biopsy companies: regulators judge these designs on whether acting on the ctDNA signal improves outcomes, not only on whether the assay detects it. The FDA’s final guidance on ctDNA in curative-intent solid tumour drug development (November 2024) sets out its current thinking. See also our pieces on ctDNA and MRD in immunotherapy trials and biomarker-driven clinical trial designs.
Team-by-team preparation
Divide the work by function rather than sending everyone to the same plenary sessions.
| Team | Before the meeting | During the meeting | Within a month after |
| Diagnostics companies (IVD, CDx, NGS, IHC) | List the late-stage trials using biomarkers your platform measures or could measure; note the assay each one used | Capture assay, cut-off, prevalence and evaluable rate; meet sponsors whose trials used local or multiple assays | Brief commercial teams on expected testing demand; open bridging or concordance talks |
| CROs and central laboratories | Map which clients have readouts due and which biomarker-defined trials may follow | Track designs that will need new screening workflows, such as serial ctDNA sampling or low-end IHC scoring | Plan capacity and validation for follow-on trials; follow up with sponsors planning confirmatory or expansion studies |
| Pharma biomarker and translational teams | Identify competitor readouts in your indications and the biomarker strategy each implies | Compare cut-offs and assays with your own programme; note any subgroup effects that could reach your label | Update the CDx plan, assay choice for upcoming trials and evidence for regulators and payers |
| CDx regulatory and medical affairs | Know which approvals and advisory meetings are pending | Separate pre-specified from exploratory results before internal summaries go out | Monitor label and guideline changes; prepare answers for labs and clinicians |
| BD and partnering | Book meetings with sponsors whose readouts are expected, before travel | Listen for unmet testing needs: assay gaps, turnaround, access | Send a specific proposal within two weeks |
After the meeting: three things to track
Label watch
A practice-changing readout starts a regulatory process. Track the drug filing, any CDx premarket approval or supplement, and the final label wording on the tested population and specified test. Our step-by-step guide to the FDA companion diagnostic pathway explains the timelines.
Guideline updates
Clinical practice guidelines often update faster than labels, sometimes adding a biomarker recommendation before a CDx is approved. For diagnostics teams, the guideline change is often what triggers routine testing and payer coverage, so track it market by market.
Partnering follow-up
The weeks after a big readout are when sponsors choose assay partners for confirmatory and expansion trials. Keep follow-up specific: the trial, the assay question, the proposal. For partnership structures, see our guide to pharma and diagnostics co-development.
How the June data season sits around focused summits
Large clinical meetings are where data appears first; detailed conversations about assays, cut-offs and partnering usually happen in smaller rooms. Our oncology conferences calendar shows the full year; for biomarker and CDx teams, the ImmunoMark editions fit like this:
| When | Meeting | Best use for biomarker and CDx teams |
| 10–11 February 2027 | ImmunoMark Summit San Diego | Set the year’s agenda: the assays, platforms and partners you want by summer |
| 3–4 March 2027 | ImmunoMark Summit London | European CDx and regulatory perspective; meet pharma teams choosing trial assays |
| June 2027 | ImmunoMark Summit Boston | Discuss what early summer readouts mean for biomarker strategy in pre-arranged 1:1 meetings |
Each edition runs two parallel streams, Next-Gen Immuno-Oncology and Biomarkers & Companion Diagnostics, with keynotes, panels, case studies, pre-arranged 1:1 meetings and a Day 1 drinks reception. At London 2026, 300+ attendees from 100+ companies took part, 70% of them senior decision-makers, including teams from GSK, Roche, Merck, AstraZeneca, J&J, BMS, Incyte and Pierre Fabre. More than 200 meetings took place, with 15–25 meetings per sponsor. Our oncology conference sponsorship page compares a focused meeting with a large congress.
FAQs
When and where is ASCO 2027?
The ASCO Annual Meeting 2027 takes place from 4 to 8 June 2027 in Chicago. The 2026 meeting ran from 29 May to 2 June 2026, also in Chicago.
How can I tell whether a biomarker subgroup result is reliable?
Check whether the biomarker population was pre-specified and formally tested within the trial’s statistical hierarchy, which assay and cut-off were used, how many patients had an evaluable sample, and whether the effect is consistent across the range of the biomarker. Post hoc subgroups are hypotheses, not evidence for a label.
What kinds of trial readouts change companion diagnostic strategy?
Four kinds: label-enabling trials in a pre-specified biomarker population, new indications created by redrawing an existing biomarker (as with HER2-low breast cancer), label narrowing by biomarker level (as with PD-L1 in HER2-negative gastric cancer), and trials that use ctDNA to guide treatment decisions.
When is ImmunoMark Summit Boston?
ImmunoMark Summit Boston, the East Coast Edition, takes place in June 2027 with 300+ attendees. Earlier 2027 editions run in San Diego on 10–11 February and London on 3–4 March.
Next stop: ImmunoMark Boston
If your team reads early summer clinical data for its biomarker implications, ImmunoMark’s immuno-oncology and biomarker summit in Boston is where to take those questions to the people choosing assays, cut-offs and CDx partners: 300+ senior pharma, biotech and diagnostics attendees in June 2027, with pre-arranged 1:1 meetings.
Register for ImmunoMark Boston
If your company wants to meet this audience, see the Boston sponsorship opportunities, including the ROI calculator.
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