A pharmaceutical company can build a perfect forecast for its own drug and still get blindsided. The model accounts for the disease, the patients, the access timelines, and the prescribing behaviour. What it fails to account for is the competitor drug entering the same space eighteen months later, changing the standard of care, and rewriting every assumption in the original plan.
Stelios Tzellos of the UK treats competitive intelligence as a discipline rather than a periodic check-in. As a professional in business insights, analytics, and oncology marketing at AstraZeneca, with earlier roles at GlobalData and IQVIA, he has built the competitive assessments that tell a company not just where the market is, but where it is going and who else is heading there.
A Forecast Without Competitors Is a Fantasy
Every market forecast makes assumptions about the competitive field, whether those assumptions are stated or not. A model that projects steady market share for a drug is implicitly assuming that no competitor disrupts it. In oncology, that assumption rarely survives contact with reality. Pipelines are crowded, mechanisms overlap, and a readout from a competitor’s trial can reshape the field in a single afternoon.
Reading the pipeline means knowing what is in development, what stage each candidate has reached, what its trial design implies, and how its mechanism might change treatment sequencing. This is structured analysis built on clinical trial registries, conference presentations, published data, and an understanding of the biology that connects them.
What the Pipeline Actually Tells You
A competitor’s trial design reveals its intentions. The choice of patient population, the comparator arm, the endpoints, and the line of therapy all signal where the drug is aiming. An analyst who reads these signals correctly can project a competitive threat long before the drug reaches the market.
Tzellos built competitive assessments at GlobalData, covering oncology and haematology indications including Hodgkin’s lymphoma. The work required tracking not just approved drugs but the candidates moving through development, and judging which ones posed a real threat versus which would stall.
The Biology Behind the Threat
Not every competitor matters equally, and telling the difference requires understanding mechanism. Two drugs aimed at the same cancer might compete directly or might serve different patient subgroups defined by molecular features. A drug with a novel mechanism might expand the treated population rather than divide the existing one.
Tzellos studied molecular biology at Imperial College London, where his doctoral research examined gene regulation in Epstein-Barr virus. That foundation lets him assess a competing drug by what it does at the mechanistic level, which is often a better predictor of competitive impact than the headline trial result.
War-Gaming the Launch
The practical output of competitive intelligence is preparation. A company that has mapped the pipeline can run scenarios. What happens to our forecast if a competitor reads out positive in first line? What if their access clears faster than ours? What if a combination regimen makes our monotherapy assumptions obsolete? Asking these questions before launch is far cheaper than answering them afterward.
At IQVIA, Tzellos worked with global clients on forecasting and evidence-based strategy, where competitive scenarios fed directly into commercial planning. At AstraZeneca, he leads cross-functional projects that keep the competitive picture in front of the teams making product decisions. A forecast that ignores the competition describes a market that will never exist.