Histology-Agnostic Drugs: A Paradigm Shift-A Narrative Review

Cancer diagnosis and therapeutics have been traditionally based on pathologic classification at the organ of origin. The availability of an unprecedented amount of clinical and biologic data provides a unique window of opportunity for the development of new drugs. What was once treated as a homogeneous disease with a one-size-fits-all approach was shown to be a rather heterogeneous condition, with multiple targetable mutations that can vary during the course of the disease. Clinical trial designs have had to adapt to the exponential growth of targetable mechanisms and new agents, with ensuing challenges that are closer to those experienced with rare diseases and orphan medicines. To face these problems, precision/enrichment and other novel trial designs have been developed, and the concept of histology-agnostic targeted therapeutic agents has emerged. Patients are selected for a specific agent based on specific genomic or molecular alterations, with the same compound used to potentially treat a multiplicity of cancers, granted that the actionable driver alteration is present. There are currently approved drugs for such indications, but this approach has raised issues on multiple levels. This review aims to address the challenges of this new concept and provide insights into possible solutions and frameworks on how to tackle them.

Modelling approaches for histology-independent cancer drugs to inform NICE appraisals: a systematic review and decision-framework

BACKGROUND

The first histology-independent marketing authorisation in Europe was granted in 2019. This was the first time that a cancer treatment was approved based on a common biomarker rather than the location in the body at which the tumour originated. This research aims to explore the implications for National Institute for Health and Care Excellence appraisals.

METHODS

Targeted reviews were undertaken to determine the type of evidence that is likely to be available at the point of marketing authorisation and the analyses required to support National Institute for Health and Care Excellence appraisals. Several challenges were identified concerning the design and conduct of trials for histology-independent products, the greater levels of heterogeneity within the licensed population and the use of surrogate end points. We identified approaches to address these challenges by reviewing key statistical literature that focuses on the design and analysis of histology-independent trials and by undertaking a systematic review to evaluate the use of response end points as surrogate outcomes for survival end points. We developed a decision framework to help to inform approval and research policies for histology-independent products. The framework explored the uncertainties and risks associated with different approval policies, including the role of further data collection, pricing schemes and stratified decision-making.

RESULTS

We found that the potential for heterogeneity in treatment effects, across tumour types or other characteristics, is likely to be a central issue for National Institute for Health and Care Excellence appraisals. Bayesian hierarchical methods may serve as a useful vehicle to assess the level of heterogeneity across tumours and to estimate the pooled treatment effects for each tumour, which can inform whether or not the assumption of homogeneity is reasonable. Our review suggests that response end points may not be reliable surrogates for survival end points. However, a surrogate-based modelling approach, which captures all relevant uncertainty, may be preferable to the use of immature survival data. Several additional sources of heterogeneity were identified as presenting potential challenges to National Institute for Health and Care Excellence appraisal, including the cost of testing, baseline risk, quality of life and routine management costs. We concluded that a range of alternative approaches will be required to address different sources of heterogeneity to support National Institute for Health and Care Excellence appraisals. An exemplar case study was developed to illustrate the nature of the assessments that may be required.

CONCLUSIONS

Adequately designed and analysed basket studies that assess the homogeneity of outcomes and allow borrowing of information across baskets, where appropriate, are recommended. Where there is evidence of heterogeneity in treatment effects and estimates of cost-effectiveness, consideration should be given to optimised recommendations. Routine presentation of the scale of the consequences of heterogeneity and decision uncertainty may provide an important additional approach to the assessments specified in the current National Institute for Health and Care Excellence methods guide.

FURTHER RESEARCH

Further exploration of Bayesian hierarchical methods could help to inform decision-makers on whether or not there is sufficient evidence of homogeneity to support pooled analyses. Further research is also required to determine the appropriate basis for apportioning genomic testing costs where there are multiple targets and to address the challenges of uncontrolled Phase II studies, including the role and use of surrogate end points.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Evidence Synthesis programme and will be published in full in Health Technology Assessment; Vol. 25, No. 76. See the NIHR Journals Library website for further project information.

The Potential Long-Term Comparative Effectiveness of Larotrectinib and Entrectinib for Second-Line Treatment of TRK Fusion-Positive Metastatic Lung Cancer

BACKGROUND

Larotrectinib and entrectinib are FDA-approved therapies for patients with non-small cell lung cancer (NSCLC) with neurotrophic receptor tyrosine kinase gene fusion (TRK fusion-positive) whose cancer has metastasized and progressed. Early evidence indicates that these targeted therapies may offer dramatic survival benefits versus traditional cytotoxic regimens, but it remains uncertain how larotrectinib and entrectinib compare with each other.

OBJECTIVE

To simulate and compare expected life-years and quality-adjusted life-years (QALYs) for both TRK inhibitors.

METHODS

We developed a partitioned survival model to project the long-term comparative effectiveness of larotrectinib versus entrectinib in second-line treatment of metastatic NSCLC. Larotrectinib survival data were derived from a 13-month follow-up of 12 patients with TRK fusion-positive NSCLC in the NCT02122913 (phase 1) and NCT02576431 (NAVIGATE) trials. Entrectinib survival data were derived from a 13-month follow-up of 10 patients with TRK fusion-positive NSCLC in the ALKA-372-001, STARTRK-1, and STARTRK-2 trials. For larotrectinib and entrectinib progression-free survival and overall survival (OS), in-trial survival was extrapolated using parametric curve fits. Exponential fits were selected for all survival models based on minimal Bayesian information criteria and clinical plausibility. Lifetime survival curves were used to estimate expected mean/median survival. QALYs were estimated by applying preprogression and postprogression health state utilities derived from the literature.

RESULTS

In the base case, treatment with larotrectinib and entrectinib resulted in 5.4 and 1.2 median preprogression life-years and 7.0 and 1.8 median total life-years, respectively. Mean preprogression life-years (QALYs) were 7.5 (5.0) and 1.9 (1.2), and mean total life-years (QALYs) were 9.2 (5.8) and 4.4 (2.4), respectively.

CONCLUSIONS

Among TRK inhibitors for metastatic NSCLC, larotrectinib is estimated to provide improved life-year and QALY outcomes versus entrectinib based on parametric extrapolations of in-trial survival data. Our analysis is limited by lack of NSCLC-specific data on entrectinib OS, the small samples of patients with NSCLC in the trials, and a cross-trial comparison. Future studies should re-evaluate the comparative effectiveness of larotrectinib versus entrectinib as more patients are treated and as long-term survival data mature.

DISCLOSURES

Funding for this study was contributed by Bayer Healthcare, which reviewed the manuscript drafts, and employees contributed to the manuscript as coauthors. Xia and Williamson are employees of Bayer Healthcare. Roth, Carlson, and Sullivan are consultants to Bayer Healthcare and retain rights to all final revisions to the manuscript. Carlson also reports fees from Adaptive Biotechnologies, unrelated to this work. Roth reports consulting fees from BMS, unrelated to this work.

Histology-agnostic drug development - considering issues beyond the tissue

With advances in tumour biology and immunology that continue to refine our understanding of cancer, therapies are now being developed to treat cancers on the basis of specific molecular alterations and markers of immune phenotypes that transcend specific tumour histologies. With the landmark approvals of pembrolizumab for the treatment of patients whose tumours have high microsatellite instability and larotrectinib and entrectinib for those harbouring NTRK fusions, a regulatory pathway has been created to facilitate the approval of histology-agnostic indications. Negative results presented in the past few years, however, highlight the intrinsic complexities faced by drug developers pursuing histology-agnostic therapeutic agents. When patient selection and statistical analysis involve multiple potentially heterogeneous histologies, guidance is needed to navigate the challenges posed by trial design. Additionally, as new therapeutic agents are tested and post-approval data become available, the regulatory framework for acting on these data requires further optimization. In this Review, we summarize the development and testing of approved histology-agnostic therapeutic agents and present data on other agents currently under development. Finally, we discuss the challenges intrinsic to histology-agnostic drug development in oncology, including biological, regulatory, design and statistical considerations.

New Targets in Lung Cancer (Excluding EGFR, ALK, ROS1)

PURPOSE OF REVIEW

Over the last two decades, the identification of targetable oncogene drivers has revolutionized the therapeutic landscape of non-small cell lung cancer (NSCLC). The extraordinary progresses made in molecular biology prompted the identification of several rare molecularly defined subgroups. In this review, we will focus on the novel and emerging actionable oncogenic drivers in NSCLC.

RECENT FINDINGS

Recently, novel oncogene drivers emerged as promising therapeutic targets besides the well-established EGFR mutations, and ALK/ROS1 rearrangements, considerably expanding the list of potential exploitable genetic aberrations. However, the therapeutic algorithm in these patients is far less defined. The identification of uncommon oncogene drivers is reshaping the diagnostic and therapeutic approach to NSCLC. The introduction of novel highly selective inhibitors is expanding the use of targeted therapies to rare and ultra-rare subsets of patients, further increasing the therapeutic armamentarium of advanced NSCLC.

Update on optimal treatment for metastatic colorectal cancer from the AGITG expert meeting: ESMO congress 2019

Introduction: Outcomes in metastatic colorectal cancer are improving, due to the tailoring of therapy enabled by better understanding of clinical behavior according to molecular subtype.Areas covered: A review of the literature and recent conference presentations was undertaken on the topic of systemic treatment of metastatic colorectal cancer. This review summarizes expert discussion of the current evidence for therapies in metastatic colorectal cancer (mCRC) based on molecular subgrouping.Expert opinion: EGFR-targeted and VEGF-targeted antibodies are now routinely incorporated into treatment strategies for mCRC. EGFR-targeted antibodies are restricted to patients with extended RAS wild-type profiles, with evidence that they should be further restricted to patients with left-sided tumors. Clinically distinct treatment pathways based on tumor RAS, BRAF, HER2 and MMR status, are now clinically applicable. Evidence suggests therapy for additional subgroups will soon be defined; the most advanced being for patients with KRAS G12 C mutation and gene TRK fusion defects.

Tropomyosin receptor kinase inhibitors: an updated patent review for 2016-2019

Introduction: Tropomyosin receptor kinases (Trks) control processes in the fields of growth, survival, and differentiation of neuronal processes. They also play a crucial role in neurodegenerative diseases as well as different types of cancer. Interest in developing Trk inhibitors to target NTRK fusion-driven cancers has escalated in the last decade, leading to the FDA approval of the pan-Trk inhibitors entrectinib and larotrectinib. The development of next-generation inhibitors that overcome resistance mutations arising from treatment with these first generation inhibitors has been the focus in recent years.Area covered: In this updated patent review for 2016-2019, patents covering inhibitors targeting the Trk family are discussed as a continuation of the previous reviews, Tropomyosin receptor kinase inhibitors: an updated patent review for 2010-2016 - Parts 1 & 2. The status of Trk inhibitors in clinical trials is also evaluated. For the identification of relevant patents and clinical trials, Web of Science, Google, Google Patents, and patent referencing were used.Expert opinion: The FDA approval of larotrectinib and entrectinib is a prime example of how basket clinical trial design targeting oncogenic drivers, regardless of tumor histology, is a viable approach to drug discovery and embodies the shift toward personalized medicine.