Surrogate endpoints for HTA decisions of breast cancer drugs: utility and pitfalls

What constitutes meaningful benefit of cancer drugs in the context of LMICs? A mixed-methods study of oncologists' perceptions on endpoints, benefit, price, and value of cancer drugs

BACKGROUND

The importance of surrogate endpoints, magnitude of clinical benefit of cancer drugs, and their prices have often been debated in the oncology world. No study, however, has systemically explored oncologists' perception regarding these issues.

METHODS

We conducted a mixed-methods study including in-depth qualitative interviews of medical oncologists prescribing cancer drug therapy in India. Quantitative data were collected using a predetermined proforma. Qualitative in-depth interviews were audio-recorded, transcribed verbatim, anonymized, subsequently coded, and analyzed by generating basic and global themes.

RESULTS

We interviewed 25 medical oncologists. Twenty-eight percent of oncologists rarely used cancer drugs that improved response rate (RR) but not overall survival (OS), and an equal percentage mostly/often used such drugs. For cancer drugs that improved progression-free survival (PFS) but not OS, 20% never/rarely used them while 48% mostly/often used them. Oncologists in India considered a 4.5-month (range, 1.5-12 months) advantage in median PFS as meaningful, and considered price of ∼120 United States Dollars (USD) per month (range, 48-720 USD per month) for those PFS gains as justified. For OS, median gains of 4.5 months (range, 2-24 months) and at a monthly price of ∼360 USD (range, 48-900 USD) was considered justified. Oncologists in India were aware and concerned that RR only meant tumour shrinkage not survival benefit, but many assumed that tumour shrinkage meant better quality of life. Many oncologists acknowledged the limitations of PFS but would use a drug with PFS benefit if it was cheaper than the drug with OS benefit.

CONCLUSIONS

Oncologists in India showed awareness of the limited surrogacy between RR/PFS and OS but assumed that RR/PFS correlated with improved quality of life and acknowledged price as a factor in deciding treatment choices. This is the first study providing a benchmark for minimum clinical benefit (4.5 months in PFS or OS) and maximum monthly price (120 USD for PFS, 360 USD for OS) deemed justifiable by oncologists practicing in low-and-middle-income countries.

Breast cancer drugs: FDA approval, development time, efficacy, clinical benefits, innovation, trials, endpoints, quality of life, value, and price

OBJECTIVE

This study analyzes the development, benefits, trial evidence, and price of new breast cancer drugs with US Food and Drug Administration (FDA) approval.

METHODS

We identified 26 drugs with 42 FDA-approved indications for early and metastatic breast cancer (2000-2023). Data were collected from FDA labels, clinicaltrials.gov, and Medicare and Medicaid. Overall survival (OS) and progression-free survival (PFS) hazard ratios (HRs) and tumor response's relative risk (RR) alongside objective response rate (ORR) were meta-analyzed.

RESULTS

The median development time for breast cancer drugs was 7.8 years (95% CI 6.2-10.8). 26% of treatments were considered innovative ("first-in-indication") with 88% acting via a targeted mechanism. 64% were small molecules, 19% antibodies, and 18% antibody-drug conjugates. 38% were approved for HR + and 31% for HER2 + breast cancer. 6 indications were for early and 36 for metastatic breast cancer. Indications utilized FDA's special programs: orphan (2%), fast track (24%), accelerated approval (19%), priority review (74%), breakthrough therapy (44%). Approval was predominantly supported by phase 3 trials (88%) of randomized controlled design (66%), enrolling a median of 585 patients (IQR 417-752) at 181 centers (IQR 142-223) across 19 countries (IQR 17-20). New drugs' HR were 0.78 for OS (95% CI 0.74-0.82) and 0.59 for PFS (95% CI 0.54-0.64) with a RR for tumor response of 1.61 (95% CI 1.46-1.76). Median improvements of OS were 2.8 months (IQR 1.8-5.8) and PFS were 4.4 months (IQR 2.2-7.1). In single-arm trials, the average ORR was 31% (95% CI 10-53). In meta-regressions, the correlation between OS/PFS was 0.34 (p = 0.031) and OS/response was 0.01 (p = 0.435). 60% of treatments had a 'high-value' ESMO-MCBS score with 14% demonstrating improvements in quality of life. The median price was $16,013 per month (95% CI 13,097-17,617). There was no association between prices and patient benefit. The median value per life year gained was $62,419 (IQR 25,840-86,062).

CONCLUSIONS

Over the past two decades, the development of innovative and effective drugs transformed the treatment landscape for breast cancer patients. Yet, investigators and regulators must safeguard that highly-priced new drugs demonstrate improvements in patient-centered clinical endpoints: overall survival and quality of life.

Global representativeness and impact of funding sources in cost-effectiveness research on systemic therapies for advanced breast cancer: A systematic review

BACKGROUND

Breast cancer (BC) is the most incident tumor and, consequently, any new intervention can potentially promote a considerable budget impact if incorporated. Cost-effectiveness (CE) studies assist in the decision-making process but may be influenced by the country's perspective of analysis and pharmaceutical industry funding.

METHODS

A systematic review of Medline, Scopus, and Web of Science from January 1st, 2012 to July 8th, 2022 was conducted to identify CE studies of tumor-targeted systemic-therapies for advanced BC. Articles without incremental cost-effectiveness ratio calculations were excluded. We extracted information on the country and class of drug studied, comparator type, authors' conflicts of interest (COI), pharmaceutical industry funding, and authors' conclusions.

RESULTS

71 studies comprising 204 CE assessments were included. The majority of studies were from the United States and Canada (44%), Asia (32%) and Europe (20%). Only 8% were from Latin America and none from Africa. 31% had pharmaceutical industry funding. The most studied drug classes were cyclin-dependent-kinase inhibitors (29%), anti-HER2 therapy (23%), anti-PD(L)1 (11%) and hormone therapy (11%). Overall, 34% of CE assessments had favorable conclusions. Pharmaceutical industry-funded articles had a higher proportion of at least one favorable conclusion (82% vs. 24%, p-value<0.001), European countries analyzed (45% vs. 9%, p-value = 0.003), and CE assessments with same class drug comparators (56% vs. 33%, p-value = 0.004).

CONCLUSIONS

Breast cancer CE literature scarcely represents low-and-middle-income countries' perspectives and is influenced by pharmaceutical industry funding which targets European countries', frequently utilizes comparisons within same-drug class, and is more likely to have favorable conclusions.