A novel, more reliable approach to use of progression-free survival as a predictor of gain in overall survival: The Ottawa PFS Predictive Model

New Anticancer Drugs: Reliably Assessing "Value" While Addressing High Prices

Countries face challenges in paying for new drugs. High prices are driven in part by exploding drug development costs, which, in turn, are driven by essential but excessive regulation. Burdensome regulation also delays drug development, and this can translate into thousands of life-years lost. We need system-wide reform that will enable less expensive, faster drug development. The speed with which COVID-19 vaccines and AIDS therapies were developed indicates this is possible if governments prioritize it. Countries also differ in how they value drugs, and generally, those willing to pay more have better, faster access. Canada is used as an example to illustrate how "incremental cost-effectiveness ratios" (ICERs) based on measures such as gains in "quality-adjusted life-years" (QALYs) may be used to determine a drug's value but are often problematic, imprecise assessments. Generally, ICER/QALY estimates inadequately consider the impact of patient crossover or long post-progression survival, therapy benefits in distinct subpopulations, positive impacts of the therapy on other healthcare or societal costs, how much governments willingly might pay for other things, etc. Furthermore, a QALY value should be higher for a lethal or uncommon disease than for a common, nonlethal disease. Compared to international comparators, Canada is particularly ineffective in initiating public funding for essential new medications. Addressing these disparities demands urgent reform.

Population Survival Kinetics Derived from Clinical Trials of Potentially Curable Lung Cancers

Using digitized data from progression-free survival (PFS) and overall survival Kaplan-Meier curves, one can assess population survival kinetics through exponential decay nonlinear regression analyses. To demonstrate their utility, we analyzed PFS curves from published curative-intent trials of non-small cell lung cancer (NSCLC) adjuvant chemotherapy, adjuvant osimertinib in resected EGFR-mutant NSCLC (ADAURA trial), chemoradiotherapy for inoperable NSCLC, and limited small cell lung cancer (SCLC). These analyses permit assessment of log-linear curve shape and estimation of the proportion of patients cured, PFS half-lives for subpopulations destined to eventually relapse, and probability of eventual relapse in patients remaining progression-free at different time points. The proportion of patients potentially cured was 41% for adjuvant controls, 58% with adjuvant chemotherapy, 17% for ADAURA controls, not assessable with adjuvant osimertinib, 15% with chemoradiotherapy, and 12% for SCLC. Median PFS half-life for relapsing subpopulations was 11.9 months for adjuvant controls, 17.4 months with adjuvant chemotherapy, 24.4 months for ADAURA controls, not assessable with osimertinib, 9.3 months with chemoradiotherapy, and 10.7 months for SCLC. For those remaining relapse-free at 2 and 5 years, the cure probability was 74%/96% for adjuvant controls, 77%/93% with adjuvant chemotherapy, 51%/94% with chemoradiation, and 39%/87% with limited SCLC. Relatively easy population kinetic analyses add useful information.

Adapting Health Technology Assessment agency standards for surrogate outcomes in early stage cancer trials: what needs to happen?

INTRODUCTION

An avalanche of early stage cancer clinical trials is coming. The majority of these solely use surrogate outcomes that have not been validated against a target outcome of interest (e.g. overall survival). Current HTA guidance on surrogate outcome validation are not methodologically or practically conducive to this scenario.

AREAS COVERED

We provide a high-level overview of methods, approaches, and conceptual thinking for making better use of limited evidence within early stage cancer HTA submissions. We outline regulatory and HTA issues and emphasize how evidence transitions from one to another, what major gaps currently exist, and how these may be bridged. We summarize current methodologies and practices, their pros and cons. We outline how complementary measurements strengthen evaluations and address fallacies and biases of conventional statistical methods for surrogate outcomes validation. The value of real-world data to support some of the necessary validity components is discussed. Lastly, we address the importance of the patient voice for better understanding which surrogate outcomes may appropriately inform HTA.

EXPERT OPINION

Conventional surrogate outcome validation represents a fraught and sub-optimal framework for HTA purposes, particularly for early stage cancer. Tools for optimizing use of limited evidence exist. Education of stakeholders is highly needed.

Pre-diagnosis fiber : carbohydrate intake ratio and mortality of ovarian cancer: results from a prospective cohort study

Background: The association between the ratio of fiber to carbohydrate (F : C-R) and cancer mortality is not currently well-known. We prospectively evaluated for the first time the aforementioned topic among ovarian cancer (OC) patients. Methods: A total of 703 newly diagnosed OC patients aged 18-79 years were included. Pre-diagnosis diet intake details were collected with a validated food frequency questionnaire. Deaths were ascertained until March 31, 2021, based on medical records and the cancer registry. Cox proportional hazard models were used to evaluate hazard ratios (HRs) and 95% confidence intervals (CIs) between pre-diagnostic fiber, carbohydrate, and F : C-R intake and OC mortality. Restricted cubic splines were used to analyze the potential nonlinear relationship between F : C-R and OC mortality. Results: During the follow-up period (median: 37.2 months; interquartile: 24.7-50.2 months), we observed 130 (18.49%) OC patients died. The pre-diagnosis higher fiber intake (comparing the highest with the lowest tertile of intake: HR = 0.56, 95% CI = 0.35-0.92; HR per 1 SD increment: 0.78, 95% CI = 0.64-0.96; P trend < 0.05) and higher F : C-R intake (comparing the highest with the lowest tertile of intake: HR = 0.51, 95% CI = 0.31-0.85; HR per 1-SD increment: 0.73; 95% CI = 0.59-0.91; P trend < 0.05) were significantly associated with lower mortality for OC patients, but no evidence of the association between pre-diagnosis carbohydrate intake and OC mortality was observed. We found no evidence of a nonlinear relationship between F : C-R and OC mortality. Significant inverse associations were also observed for subgroup analyses stratified by age at diagnosis, menopausal status, residual lesions, histological type, FIGO stage, and body mass index, although not all associations showed statistical significance. Conclusion: Pre-diagnosis high fiber intake and high F : C-R diet intake were associated with a decreased risk of OC mortality.

Treatment Access, Health Economics, and the Wave of a Magic Wand

New drugs are expensive, in part due to excessive drug development costs. Governments are trying to reduce drug prices. This can delay access to effective agents. A country’s access to new drugs correlates with prices they agree to pay. After Health Canada approves a drug, the Canadian Agency for Drug and Technologies in Health (CADTH) assesses it. CADTH’s approval is usually contingent on it costing ≤CAD 50,000 per quality adjusted life year (QALY) gained. This value (unchanged from the 1970s) is inappropriately low. An inflation-adjusted CAD 50,000 1975 QALY should translate into a CAD 250,000 2021 QALY. CADTH’s target also does not consider that drug development costs have risen much faster than inflation or that new precision therapies may only be used in small populations. In a separate process, proposals from the Patented Medicines Price Review Board (PMPRB) would decrease initial Canadian drug prices by 20%, but prices would fall further as sales increased, with ultimate price reductions of up to 80%. PMPRB claims its proposal would not reduce drug access, but multiple analyses strongly suggest otherwise. Government price controls target the symptom (high prices), not the disease. They translate into shortages without solving the problem. CADTH and PMPRB approaches both threaten access to effective drugs.

The need for speed in advanced non-small cell lung cancer: A population kinetics assessment

BACKGROUND

Systemic therapy prolongs overall survival (OS) in advanced non-small cell lung cancer (NSCLC), but diagnostic tests, staging and molecular profiling take time, and this can delay therapy initiation. OS approximates first-order kinetics.

METHODS

We used OS of chemo-naive NSCLC patients on a placebo/best supportive care trial arm to estimate % of patients dying while awaiting therapy. We digitized survival curves from eight studies, calculated OS half-life, then estimated the proportion surviving after different times of interest (t_n ) using the formula: X = exp - t n ∗ 0 .693 / t 1 / 2 , where EXP signifies exponential, * indicates multiplication, 0.693 is the natural log of 2, and t_1/2 is the survival half-life in weeks.

RESULTS

Across trials, the OS half-life for placebo/best supportive care in previously untreated NSCLC was 19.5 weeks. Hence, based on calculations using the formula above, if therapy were delayed by 1, 2, 3, or 4 weeks then 4%, 7%, 10%, and 13% of all patients, respectively, would die while awaiting treatment. Others would become too sick to consider therapy even if still alive.

CONCLUSIONS

This quantifies why rapid baseline testing and prompt therapy initiation are important in advanced NSCLC. It also illustrates why screening procedures for clinical trial inclusion must be faster. Otherwise, it is potentially hazardous for a patient to be considered for a trial due to risk of death or deterioration while awaiting eligibility assessment. It is also important to not delay initiation of systemic therapy for procedures that add relatively little value, such as radiotherapy for small, asymptomatic brain metastases.

Potential insights from population kinetic assessment of progression-free survival curves

Progression-free survival (PFS) curves follow first order kinetics on exponential decay nonlinear regression analysis (EDNLRA). Some exhibit 1-phase-decay, some have 2-phase-decay, some are convex. We digitized, performed EDNLRA and generated log-linear plots for 887 published PFS curves for incurable solid tumors treated with various systemic therapies. Proportion of curves fitting 2-phase-decay varied by therapy (p < 0.0001). For 13 therapies, >64 % of PFS curves had 2-phase-decay. This included epidermal growth factor receptor inhibitors in unselected lung cancer patients (some with, some without mutations), immune checkpoint inhibitors, interferon, breast cancer hormonal therapies, and selected others, suggesting 2 distinct, potentially identifiable subpopulations with differing progression rates. For 22 other therapies, <25 % of PFS curves had 2-phase-decay. Only 1 therapy was in the mid-range. Small cell lung and colon carcinomas were particularly likely to yield highly convex curves (p < 0.006), probably from discontinuation of effective therapies. PFS curve shape may yield biological and clinical insights.