Olaparib for adjuvant treatment of BRCA mutation-positive HER2-negative high-risk early breast cancer after chemotherapy

3.1 The patient experts explained that BRCA mutation-positive HER2‑negative high-risk early breast cancer is an aggressive form of cancer with poor outcomes. They also explained that it can be very distressing for people with the condition. It includes hormone receptor-positive and triple-negative breast cancer, the latter having the poorest prognosis. The patient experts explained that there are limited treatment options available for the condition, particularly for triple-negative breast cancer. They thought that many people who have had olaparib appreciated having access to an extra treatment option that has been shown to improve survival. People with HER2‑negative high-risk early breast cancer often worry about the increased risk of their cancer returning after treatment. Also, people with BRCA mutation-positive breast cancer have concerns about whether their relatives have the BRCA1 or 2 mutations and so an increased risk of developing cancer. Having a treatment that has been shown to improve outcomes has a positive effect on mental health. One of the patient experts who had had olaparib highlighted that it is a convenient oral treatment, and only infrequent hospital visits are needed for monitoring. They explained that olaparib's side effects were manageable. They also said that they were able to continue their usual daily activities and maintain a good quality of life while having it, although they did have fatigue. The committee concluded that olaparib would be a welcome adjuvant treatment option to improve outcomes in people with BRCA mutation-positive HER2‑negative high-risk early breast cancer.

3.2 The committee noted that current standard care for BRCA mutation-positive HER2‑negative high-risk early breast cancer is neoadjuvant chemotherapy followed by surgery and surveillance, or surgery followed by adjuvant chemotherapy. The most common chemotherapy regimen is an anthracycline taxane combination plus a platinum therapy. People with hormone receptor-positive HER2‑negative breast cancer may also have adjuvant endocrine therapy after surgery. The committee noted that olaparib would be used after neoadjuvant or adjuvant chemotherapy, either:

3.3 The clinical evidence came from OlympiA, a randomised double-blind placebo-controlled trial (n=1,836). It was done in 23 countries worldwide and included 106 people from the UK. The trial compared olaparib with placebo in people with (germline) BRCA mutation-positive HER2‑negative high-risk early breast cancer. People in the trial had either had neoadjuvant or adjuvant treatment at the point of randomisation. The criteria for defining high risk in OlympiA were:

3.4 The primary outcome in OlympiA was invasive disease-free survival. Secondary outcomes included distant disease-free survival and overall survival. A statistically significant difference in all 3 outcomes was shown with olaparib compared with placebo:

3.5 For the subgroup of people in OlympiA who had triple-negative breast cancer, olaparib statistically significantly improved invasive disease-free survival compared with placebo. For the subgroup of people with hormone receptor-positive HER2‑negative breast cancer, the results were consistent with the overall population but were not statistically significant. The clinical experts advised that this was because:

3.6 The company presented a 5‑state semi-Markov model to estimate the cost effectiveness of adjuvant treatment with olaparib compared with routine monitoring in people with BRCA mutation-positive HER2‑negative high-risk early breast cancer previously treated with adjuvant or neoadjuvant chemotherapy. The 5 health states were: disease-free; non-metastatic breast cancer (local recurrence); early-onset metastatic breast cancer (recurrence within 2 years); late-onset metastatic breast cancer (recurrence after 2 years); and death. The model estimated the cost effectiveness of olaparib in people with triple-negative breast cancer and people with hormone receptor-positive HER2‑negative breast cancer separately. The EAG described the model as high-quality and largely aligned with NICE's methods for economic evaluation. The committee concluded that the model was suitable for decision making.

3.7 There was no long-term data from OlympiA to use in the economic model. So, the company and the EAG had to extrapolate the data and make assumptions about recurrence using expert opinion and the published literature. The company used a log-normal distribution to model the risk of recurrence in both the triple-negative and hormone receptor-positive HER2‑negative breast cancer populations. The EAG agreed with the log-normal distribution for the triple-negative population but thought that this was too optimistic for the hormone receptor-positive HER2‑negative population. It preferred the generalised gamma distribution. This gave the smallest difference in long-term invasive disease-free survival for this subgroup. It also resulted in there being an equal risk of recurrence in the olaparib and placebo groups at an earlier time point (5.4 years compared with 14.5 years in the company's model). The company provided scenario analyses varying the time point at which the risk of recurrence was equal, but this only had a small effect on incremental cost-effectiveness ratios (ICERs). The committee agreed that there was insufficient evidence to make an informed decision about whether a log-normal or generalised gamma distribution was more suitable without further follow up from the trial. It noted the clinical experts' opinion that, for long-term invasive disease-free survival, there was little difference between the 2 distributions.

3.8 For people with hormone receptor-positive HER2‑negative breast cancer, the company and EAG assumed that the risk of recurrence remained elevated throughout the lifetime horizon of the model. But, for people with triple-negative breast cancer, the company and EAG made different assumptions. The company assumed that, after 5 years, there was a 0% chance of recurrence, while the EAG assumed a 5% risk from year 5 to year 15. The clinical experts explained that most recurrences in people with triple‑negative breast cancer occur in the first 2 to 3 years after diagnosis. They also said that the risk of recurrence after 5 years is very low, although it is not likely to be 0%. They estimated that there may be a 2% to 3% risk of recurrence between year 5 and year 8, and 0% after 8 years. The committee concluded that assuming a 2% to 3% risk of recurrence between year 5 and year 8, while uncertain, was reasonable.

3.9 The company and the EAG used different extrapolation curves for estimating survival after early metastatic recurrence. The company used an exponential distribution and the EAG used the Gompertz distribution. The EAG argued that using an exponential distribution is unsuitable when the data violates the proportional hazards assumption. It highlighted that the company had presented evidence that hazards between arms were non-proportional. Both Kaplan–Meier curves and log-cumulative hazards indicated violation of proportional hazards. The EAG thought that the Gompertz distribution gave the most plausible survival difference between arms and, given the long-term uncertainty, was more conservative. The clinical experts noted that the latest publication of the OlympiA data showed that the proportional hazards assumption was met for survival. The committee noted that the choice of extrapolation method had a small effect on the ICER, so did not discuss this further.

3.10 The utility values used in the modelling were a key driver of the cost-effectiveness results, particularly the values for the disease-free health state. The company used health-related quality-of-life data from the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ‑C30) in OlympiA, mapped to EQ‑5D‑3L to estimate the utility value for the disease-free health state. It set the non-metastatic breast cancer (local recurrence) utility value to be the same as that for the disease-free health state because the difference between the two was non-significant in the trial. The metastatic breast cancer utility value was sourced from external literature. The EAG had 2 issues with the company's approach. Firstly, it believed that there was a risk of bias because of low completion rates of the EORTC QLQ‑C30 questionnaires. Secondly, it had concerns about the algorithms used to map the data to EQ‑5D‑3L. The EAG highlighted that older algorithms, such as the Crott and Briggs algorithm used in the company's base case, have been shown to produce biased estimates. It also explained that newer algorithms have had insufficient external validation. The committee noted these limitations and questioned whether the company's estimates were plausible. It noted that these were 0.869 for the disease-free and the non-metastatic breast cancer health states and 0.685 for the metastatic breast cancer health state. The committee appreciated that the utility values were estimated from the health-related quality-of-life data in OlympiA. But it was concerned that the values were unrealistically high because the disease-free value was only slightly lower than that of age-matched people in the general population (0.877). The committee considered this to be implausible because people taking olaparib would recently have had both surgery and chemotherapy. Also, this value was not consistent with other technology appraisals of treatments for triple-negative breast cancer. The committee was also not convinced that it was realistic to assume the same utility for the disease-free and non-metastatic breast cancer (local recurrence) health states. This was because of the anxiety associated with having a local recurrence and probable further surgery, possibly including mastectomy. The committee was also aware that the utility values used by the company for metastatic breast cancer were generally higher than those used in some other technology appraisals. For these reasons, the committee concluded that the company's utility values were not appropriate.

3.11 The EAG used utility values from an external UK study (Verrill et al. 2020) in people with HER2‑positive breast cancer (108 with early and 102 with metastatic breast cancer). This study directly measured health-related quality of life using the EQ‑5D questionnaire. The values were 0.732 for the disease-free, 0.668 for non-metastatic breast cancer and 0.603 for metastatic breast cancer health states. The EAG chose a value for non-metastatic breast cancer that was the midpoint between the disease-free and metastatic breast cancer health states. The committee noted that the estimates were much lower than the company's estimates, possibly because of the older population in Verrill et al. compared with OlympiA. The EAG also presented a sensitivity analysis adjusting for the age difference between Verrill et al. and OlympiA. This increased the utility values to 0.770 for the disease-free, 0.702 for non-metastatic breast cancer and 0.634 for metastatic breast cancer health states. The committee accepted that using the utilities from Verrill et al. had some limitations because of differences in the populations. But it concluded that the utility values from the EAG's age-adjusted estimates using Verrill et al. were the most appropriate of the ones presented by the company and EAG.

3.12 The company assumed that olaparib was not associated with additional costs for BRCA testing, which is needed to determine eligibility for olaparib. The rationale for this was that most people with HER2‑negative high-risk early breast cancer will have routine BRCA screening as part of standard care in the NHS. The EAG questioned whether this was the case for people with hormone receptor-positive HER2‑negative early breast cancer and preferred to include BRCA testing costs for this group. The company submitted data suggesting that most people with hormone receptor-positive HER2‑negative high-risk early breast cancer who are potentially eligible for olaparib would already be identified for BRCA testing if the current National Genetic Test Directory criteria were uniformly implemented in clinical practice. This was because OlympiA only recruited people with breast cancer at high risk of recurrence. The clinical experts agreed that most people with hormone receptor-positive HER2‑negative high-risk early breast cancer would be eligible for testing and that training for clinicians would increase implementation. The committee accepted that most people with HER2‑negative early breast cancer at high risk of recurrence meet the current testing criteria, so BRCA testing costs did not need be included in the model.

3.13 The company argued that discount rates of 1.5% for costs and outcomes should be applied for the triple-negative breast cancer population instead of rates of 3.5%. The company presented a scenario analysis using the lower rates and this reduced the ICER in the triple-negative breast cancer population substantially. But the committee noted that, for the 1.5% rates to be applicable, the treatment would have to:

3.14 The base-case ICERs originally submitted by the company for olaparib compared with routine monitoring were above the range normally considered a cost-effective use of NHS resources. That range is £20,000 to £30,000 per quality-adjusted life year (QALY) gained. This was true for both the triple-negative and the hormone receptor-positive HER2‑negative early breast cancer populations. None of the company's scenario analyses substantially changed the results, apart from an analysis that used 1.5% discount rates for costs and outcomes. But the committee had concluded that was not appropriate (see section 3.13). Incorporating the committee's preferred assumptions on utility values (see section 3.10 and section 3.11), and on risk of recurrence in the triple-negative early breast cancer population (see section 3.8), increased the company's ICERs further. After the first committee meeting, the company updated its commercial arrangement and submitted a new analysis using the committee's preferred assumptions. The change to the commercial arrangement resulted in ICERs that were substantially below £30,000 per QALY gained. The ICERs cannot be reported here because of confidential commercial arrangements for subsequent treatments in the pathway. The committee concluded that olaparib is a cost-effective adjuvant treatment for BRCA mutation-positive HER2‑negative high-risk early breast cancer after chemotherapy.

3.15 The committee recognised the unmet need for treatment options for people with BRCA mutation-positive HER2‑negative high-risk early breast cancer (see section 3.1). It also agreed that olaparib is an effective treatment (see section 3.4). After the first committee meeting, the company updated its cost-effectiveness analysis, adopting the committee's preferred assumptions and including a revised commercial arrangement. This reduced the ICERs to substantially below £30,000 per QALY gained. The committee concluded that olaparib is a cost-effective adjuvant treatment for BRCA mutation-positive HER2‑negative high-risk early breast cancer after chemotherapy.