Kunal Potnis, MD, Yale School of Medicine, New Haven, Connecticut, discusses an analysis of the cost-effectiveness of ribociclib plus endocrine therapy compared to endocrine therapy alone among patients with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative early breast cancer. 

Results demonstrated that ribociclib plus endocrine therapy is less cost-effective than endocrine therapy alone. Dr Potnis emphasized that cost-effectiveness analyses should “be used at the population level by folks who are interested in understanding how to best allocate resources at a budget level” and should not “be used at the individual level and certainly do not guide what sort of therapies that physicians are prescribing for their patients.”

Dr Potnis presented these results at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago, Illinois. 

Transcript: 

Hi, my name is Dr Kunal Potnis, I am a resident physician in internal medicine at the Yale School of Medicine, and I'm excited to be here at ASCO this year presenting my team's work looking at the cost-effectiveness of ribociclib plus endocrine therapy in patients with HR-positive, HER2-negative early breast cancer in the United States. 

Just by way of some background, hormone receptor, or HR-positive, HER2-negative breast cancer is the most common type of breast cancer in the United States, accounting for about 70% to 75% of cases, and generally these cases are detected early, they're treated with curative intent, but in some cases, actually about 27% to 57% of cases, patients experience recurrence. In the last several years, there's been a lot of attention put into what do we do for these patients and CDK4/6 inhibitors in the last few years have gained a lot of attention, first in the advanced breast cancer space and more recently in the early breast cancer space. 

Last year in the New England Journal [of Medicine], the phase 3 NATALEE trial was published which looked at ribociclib, which is a CDK4/6 inhibitor, plus endocrine therapy compared to endocrine therapy alone in patients with HR-positive, HER2-negative breast cancer. In the study, the authors found that the patients that received ribociclib plus endocrine therapy actually had an improved invasive disease-free survival compared to the patients that received endocrine therapy alone; it was about 90% versus 87%, which was found to be statistically significant. 

I think it's worth mentioning that CDK4/6 inhibitors, including ribociclib, can be quite costly. In the case of ribociclib, looking at the average wholesale price it can cost about $12 000 per month, taking into account discounts that are applied to payers that can be more like $8 600 per month, but still a cost to be considered. 

Our team looked at the cost-effectiveness of ribociclib plus endocrine therapy versus endocrine therapy alone in this patient population in the United States. And to do this, our team constructed a partitioned survival model using clinical data from the NATALEE trial. Our costs were informed by discounted average wholesale price, Medicare data, as well as prior work. Our utilities were informed by prior work in the early breast cancer space among patients who are HR-positive, HER2-negative and in terms of outcomes, we were interested in the ICER, the incremental cost effectiveness ratio, which we looked at from 2 different perspectives. One, we looked at US dollars per quality adjusted life year, which is a pretty standard outcome used in this kind of work. We also looked at equal value life year, which doesn't factor in quality of life but, some have argued that this outcome has a little bit more of a role in achieving a more equitable discussion of therapies. We took a US payor perspective, and we did our analysis over a 10-year time horizon. In addition to these base case analyses, we did sensitivity analyses, deterministic, probabilistic, basically 1, to get a sense of which parameters our model was the most sensitive to and 2, to understand how much uncertainty in all of our parameters were affecting our conclusion. 

Ultimately, we found that when looking at the ICER for ribociclib plus endocrine therapy compared to endocrine therapy alone, we found that the ICER was about $1.3 million per quality, or $1.2 million per equal value life year, so the endocrine therapy alone strategy was favored in that case. And when looking at our probabilistic sensitivity analysis, endocrine therapy alone was favored in 100% of our 10 000 Monte Carlo simulations, which strengthened that result.

I think [there are] a few takeaways from our study, 1 at current pricing, we found that ribociclib plus endocrine therapy was most likely not cost effective in this patient population. And we did a threshold analysis and found that a 90% price reduction would be required for ribociclib in order for it to be cost effective at even the highest commonly accepted willingness to pay threshold in the United States, which is $150 000 per quality. We also found that our results were consistent with similar analyses that have been done around the world looking at this same set of comparators in the same patient population in China, in India. 

And the last thing I will say is cost-effectiveness analyses, they're meant to be used at the population level by folks who are interested in understanding how to best allocate resources at a budget level. They're not really quite meant to be used at the individual level and certainly do not guide what sort of therapies that physicians are prescribing for their patients. That is a very individual level decision and just something I want to make crystal clear. 

Moving forward, our team will be looking at a few different things, we'll be keeping an eye out for any more longer term data in this patient population, we'll be looking for any new utility data, anything that can help refine our conclusion but, at the current moment, did not find ribociclib plus endocrine therapy to be cost effective in these patients.

Source: 

Potnis K, Ito S, Kunst N, et al. Cost-effectiveness of ribociclib plus endocrine therapy in HR-positive, HER2-negative early breast cancer in the United States. Presented at 2025 ASCO Annual Meeting. May 30-June 3, 2025; Chicago, IL. Abstract 11049