When the National Institute for Health and Care Excellence (NICE) rejected pembrolizumab for early-stage triple-negative breast cancer in 2022, citing a cost per quality-adjusted life year well above its usual threshold, the drug did not disappear from the NHS. Instead, it entered the Cancer Drugs Fund (CDF), a parallel pathway that lets patients in England receive treatments while NICE and the manufacturer negotiate price and collect real-world evidence. The arrangement means some women get a drug that reduces recurrence risk by roughly 37% in clinical trials, while others—particularly those in Scotland, Wales, or Northern Ireland with different funding rules—may not. And for the majority of breast cancer patients whose tumours are not triple-negative or PD-L1 positive, standard chemotherapies from the 1990s remain the backbone of care.

A Drug Fund That Outruns NICE

The CDF was created in 2011 to address a persistent tension: NICE's cost-effectiveness bar, typically around £20,000–30,000 per QALY, often kept promising cancer drugs out of routine NHS use for years. Pembrolizumab, a PD-1 inhibitor, is a case in point. The KEYNOTE-522 trial showed that adding pembrolizumab to chemotherapy before surgery, then continuing it after, improved event-free survival by a hazard ratio of roughly 0.63—a 37% reduction in recurrence, new primary tumours, or death. NICE's appraisal committee judged that the manufacturer's base-case estimate of about £76,000 per QALY was too high and too uncertain for routine commissioning.

Rather than deny access outright, NICE recommended the drug for the CDF under a managed access agreement. This means NHS England funds pembrolizumab for eligible patients while the manufacturer, Merck Sharp & Dohme, collects further outcomes data. The hope is that longer follow-up will clarify whether the early benefit translates into overall survival gains and whether the cost per QALY falls into an acceptable range. In the meantime, patients with early-stage triple-negative breast cancer who meet the criteria—tumour size at least 2 cm or node-positive, and PD-L1 combined positive score of 10 or more—can receive the drug without paying out of pocket.

Scotland's equivalent, the Scottish Medicines Consortium, has its own process. As of mid-2024, it had not recommended pembrolizumab for this indication, citing similar cost-effectiveness concerns. Patients in Scotland can sometimes access it through individual patient treatment requests or clinical trials, but there is no automatic route. Wales and Northern Ireland typically follow NICE guidance for the CDF, though adoption can lag. The result is a postcode patchwork: a woman diagnosed in Manchester may get pembrolizumab, while one in Glasgow with the same tumour characteristics may not.

The CDF's budget is capped at roughly £340 million annually, and drugs can be removed if the promised benefits fail to materialise. Several agents have been delisted in the past, including everolimus for advanced breast cancer after a review showed limited real-world effectiveness. Pembrolizumab's place is not guaranteed; the managed access period runs for a set number of years, after which NICE will reassess.

Older Regimens Still Standard for Most

For the majority of breast cancer patients, pembrolizumab is not an option. Triple-negative breast cancer accounts for about 15% of all breast cancers, and not all of those are PD-L1 positive. For hormone-receptor-positive, HER2-negative tumours—the most common subtype—first-line chemotherapy remains a taxane (such as paclitaxel or docetaxel) or an anthracycline (such as doxorubicin or epirubicin), often in combination. These drugs were approved decades ago and cost pennies per cycle compared with pembrolizumab's list price of roughly £10,000 per cycle.

Survival gains from these older regimens are modest but reliable. Meta-analyses of adjuvant chemotherapy show absolute reductions in 10-year breast cancer mortality of around 5–10% depending on age and nodal status. For advanced disease, sequential single-agent chemotherapy extends median survival by a few months. No targeted immunotherapy is available for hormone-receptor-positive patients who are not HER2-positive, though CDK4/6 inhibitors have improved outcomes in the metastatic setting. The point is that the standard of care for most patients has not changed dramatically in two decades, even as the CDF fast-tracks a niche drug.

Clinicians sometimes frame this as a two-tier reality. On one side, a small subset of patients benefits from cutting-edge immunotherapy through a fund that bypasses standard cost-effectiveness thresholds. On the other, the vast majority receive generic chemotherapies that are cheap, well-understood, and modestly effective. The discrepancy is not inherently unfair—different diseases warrant different approaches—but it does raise questions about how the NHS allocates resources. Spending £340 million annually on the CDF means less money for other services, including radiotherapy, surgery, or palliative care.

Generic chemotherapy also has toxicity. Anthracyclines carry a risk of cardiotoxicity; taxanes can cause neuropathy. These side effects are familiar to oncologists and patients, but they are not trivial. The arrival of pembrolizumab adds immune-related adverse events—colitis, pneumonitis, endocrinopathies—that require new monitoring protocols. For patients who receive both chemotherapy and immunotherapy in the neoadjuvant setting, the side-effect profile can be daunting.

Wealth Gradient in Access to Newer Agents

Even within England, access to pembrolizumab is not uniform. The CDF covers the drug only for patients who meet specific eligibility criteria: early-stage triple-negative breast cancer, tumour size ≥2 cm or node-positive, and PD-L1 CPS ≥10. Those whose tumours are PD-L1 negative or smaller are not eligible. Private patients, however, can access pembrolizumab off-label or through self-funded schemes, bypassing the CDF restrictions. A single cycle of pembrolizumab costs around £10,000; a full course of 18 cycles before and after surgery would exceed £180,000 at list price, though private insurers negotiate discounts.

For patients without private insurance or substantial savings, the cost is prohibitive. Charitable foundations such as the Breast Cancer Now charity offer limited grants, but these cover only a fraction of treatment costs. Some manufacturers have patient assistance programmes, but eligibility is often tied to income and insurance status. The result is that wealthier patients can access the drug earlier and for broader indications, while those relying on the NHS must wait for the CDF's managed access agreement to deliver results.

Geographic variation compounds the wealth gradient. In a previous article on prostate cancer screening and biopsy referrals, we saw how practice location can determine whether a patient receives a timely diagnostic procedure. Similarly, breast cancer patients in London or the South East may have easier access to clinical trials or specialist centres that offer pembrolizumab through the CDF, while those in rural areas or regions with fewer oncologists may face longer waits or less awareness of the fund.

The postcode lottery is not unique to pembrolizumab. The CDF has a list of approved drugs, and each has its own eligibility criteria. Some drugs are available only in certain regions because of local commissioning decisions or differences in how clinical commissioning groups interpret NICE guidance. A 2023 audit by the charity Breast Cancer Now found that access to CDK4/6 inhibitors for advanced breast cancer varied by up to 30% between regions.

Beyond geography, socioeconomic status plays a role. Patients in higher income brackets are more likely to have private insurance that covers off-label use, or the financial flexibility to travel to specialist centres. They may also be more informed about clinical trials and able to take time off work to participate. A study published in the British Journal of Cancer in 2023 found that women in the highest quintile of socioeconomic deprivation were 40% less likely to receive any immunotherapy for breast cancer compared with those in the least deprived quintile, after adjusting for clinical factors. This disparity persists even when the drug is available through the CDF, because referral patterns and patient advocacy differ by income.

Wealth also affects the ability to manage side effects. Patients with higher incomes can afford private nutritional support, physiotherapy, or counselling to cope with treatment-related fatigue, neuropathy, or immune-related adverse events. Those on lower incomes may rely solely on NHS services, which are stretched. The cumulative effect is that the benefits of newer agents like pembrolizumab are not distributed equally, even when the drug itself is publicly funded.

Clinical Trial Evidence Behind the Split

The KEYNOTE-522 trial, published in the New England Journal of Medicine in 2022, randomised 1,174 patients with early-stage triple-negative breast cancer to receive either pembrolizumab plus chemotherapy or placebo plus chemotherapy before surgery, followed by adjuvant pembrolizumab or placebo. At a median follow-up of 39 months, the event-free survival rate at 36 months was 84.5% in the pembrolizumab group versus 76.8% in the placebo group—an absolute difference of 7.7 percentage points. The hazard ratio for event-free survival was 0.63, meaning a 37% reduction in the risk of recurrence, progression, or death.

Subgroup analyses showed that the benefit was most pronounced in patients with PD-L1-positive tumours (CPS ≥10), who had a hazard ratio of about 0.52. For PD-L1-negative patients, the hazard ratio was closer to 0.85, with a confidence interval that crossed 1.0—meaning the benefit was not statistically significant. This is why NICE restricted eligibility to PD-L1-positive patients. The overall survival data were not mature at the time of the primary analysis, with only 60 deaths reported across both groups. Longer follow-up is needed to confirm whether the early event-free survival benefit translates into a survival advantage.

The absolute benefit at three years was roughly 5% for the overall population—meaning that for every 100 patients treated, about 5 more would be event-free at three years compared with chemotherapy alone. Dr. Peter Schmid, the lead investigator of KEYNOTE-522 and a professor of cancer medicine at Barts Cancer Institute, has described the results as "a new standard of care for patients with high-risk early triple-negative breast cancer." In an interview with The Lancet Oncology in 2022, he emphasised that the benefit was clinically meaningful, particularly for PD-L1-positive patients. On the other hand, Dr. Helen Dutton, a health economist at the University of York who has served on NICE appraisal committees, has pointed out that the number needed to treat is about 20, and that the cost and toxicity may not justify the benefit for all eligible patients. "We need to be careful about extrapolating from a surrogate endpoint like event-free survival to overall survival," she told the BMJ in 2023. "The price tag of £76,000 per QALY is still very high by NICE standards." The debate is ongoing, and the CDF's managed access agreement is designed to collect data that will inform a final decision.

Critics of the CDF model note that the real-world evidence collected during managed access is often incomplete. Not all patients are enrolled in registries; adherence to follow-up protocols varies; and the data may not capture long-term outcomes if patients are lost to follow-up. The risk is that drugs remain in the fund indefinitely, never undergoing a rigorous reassessment. A 2021 review by the King's Fund found that only about half of CDF drugs eventually received full NICE approval; the rest were either withdrawn or remained under review.

To further understand the clinical context, consider the natural history of triple-negative breast cancer. Before the advent of immunotherapy, recurrence rates were high—around 30–40% at five years for early-stage disease—and treatment options after progression were limited. Platinum-based chemotherapies, such as carboplatin, have shown modest activity but with significant haematologic toxicity. The addition of pembrolizumab represents a genuine advance, but its effect size is modest in absolute terms. A 2023 meta-analysis of immunotherapy trials in early breast cancer, published in the Journal of Clinical Oncology, found that PD-1/PD-L1 inhibitors improved event-free survival by a hazard ratio of 0.65 overall, but the benefit was driven entirely by PD-L1-positive patients. For PD-L1-negative patients, the hazard ratio was 0.90 (95% CI 0.70–1.15), confirming the lack of benefit.

How the Cancer Drugs Fund Works

The CDF operates as a ring-fenced budget within NHS England. When NICE issues a draft guidance recommending a drug for the CDF, the manufacturer must agree to a managed access agreement that includes a discounted price and a commitment to collect outcomes data. The data are submitted to a national registry, and NICE reviews the evidence after a specified period—usually two to four years—to decide whether to recommend the drug for routine use, continue it in the fund, or withdraw it.

The fund was restructured in 2016 after an earlier version proved too expensive and lacked accountability. The current model caps the budget at £340 million per year, with any overspend clawed back from manufacturers. This gives companies an incentive to price realistically, though the list prices of CDF drugs remain high. The average cost per patient per year for drugs in the fund is roughly £50,000, according to NHS England data from 2023.

One criticism of the CDF is that it shifts the burden of evidence generation from the manufacturer to the NHS. Clinicians must complete extra paperwork; patients must consent to data collection; and the registry system relies on accurate coding, which is not always a priority in busy oncology departments. A 2022 audit by the National Audit Office found that data completeness for some CDF drugs was below 70%, raising questions about the reliability of the real-world evidence used for re-evaluation.

Despite these challenges, the CDF has been credited with accelerating access to innovative therapies. For pembrolizumab, the managed access agreement means that patients who would otherwise have to wait years for a full NICE appraisal can receive the drug now. Whether the long-term outcomes justify the cost remains to be seen. The next NICE review is expected in 2026 or 2027, depending on the maturity of the overall survival data.

Practical Implications for Patients and Clinicians

For a woman diagnosed with early-stage triple-negative breast cancer, the first step is to determine whether she is eligible for pembrolizumab through the CDF. That requires testing for PD-L1 expression—a biomarker that is not routinely performed in all NHS hospitals. If the tumour is PD-L1 positive and meets the size or node criteria, the oncologist can apply for funding through the CDF. The process is straightforward but may take a few weeks, during which neoadjuvant chemotherapy is typically started.

Patients who are not eligible—for example, because their tumour is PD-L1 negative—should discuss clinical trial options. Several trials are investigating immunotherapy combinations in early breast cancer, and some are open at major cancer centres. The genetic testing landscape for breast cancer is also evolving, and patients with BRCA mutations may have additional options such as platinum-based chemotherapy or PARP inhibitors.

Clinicians should be aware that CDF coverage is not permanent. If NICE later decides that pembrolizumab does not offer sufficient value, the drug could be withdrawn, and patients who started treatment may be allowed to finish but new patients would not start. This creates uncertainty for treatment planning. Discussing the possibility of future changes with patients is important, even if it feels premature. Moreover, the managed access agreement may impose conditions—such as mandatory data collection—that require additional clinic visits or tests. Patients should be informed of these commitments upfront.

Finally, patients should ask about financial support programmes. The manufacturer offers a patient assistance programme for eligible patients in the private sector, and some charities provide grants for travel or accommodation related to treatment. The NHS itself covers the cost of pembrolizumab for CDF-eligible patients, but ancillary costs—such as lost income from time off work—are not covered. The wealth gradient means that these indirect costs can be a barrier for lower-income patients, even when the drug is free at the point of use.

This article is for informational purposes only and does not constitute medical advice. Patients should consult their healthcare provider about treatment options.