Larotrectinib versus Prior Therapies in Tropomyosin Receptor Kinase Fusion Cancer: An Intra-Patient Comparative Analysis

Larotrectinib efficacy and safety in adult patients with tropomyosin receptor kinase fusion sarcomas

BACKGROUND

Larotrectinib, a first-in-class, highly selective tropomyosin receptor kinase (TRK) inhibitor, has demonstrated efficacy in adult and pediatric patients with various solid tumors harboring NTRK gene fusions. This subset analysis focuses on the efficacy and safety of larotrectinib in an expanded cohort of adult patients with TRK fusion sarcomas.

METHODS

Patients (≥18 years old) with sarcomas harboring NTRK gene fusions were identified from three clinical trials. Patients received larotrectinib 100 mg orally twice daily. Response was investigator-assessed per RECIST v1.1. Data cutoff was July 20, 2021.

RESULTS

At the data cutoff, 36 adult patients with TRK fusion sarcomas had initiated larotrectinib therapy: two (6%) patients had bone sarcomas, four (11%) had gastrointestinal stromal tumors, and 30 (83%) had soft tissue sarcomas. All patients were evaluable for response and demonstrated an objective response rate of 58% (95% confidence interval, 41-74). Patients responded well to larotrectinib regardless of number of prior lines of therapy. Adverse events (AEs) were mostly grade 1/2. Grade 3 treatment-emergent AEs (TEAEs) occurred in 15 (42%) patients. There were no grade 4 TEAEs. Two grade 5 TEAEs were reported, neither of which were considered related to larotrectinib. Four (11%) patients permanently discontinued treatment due to TEAEs.

CONCLUSIONS

Larotrectinib demonstrated robust and durable responses, extended survival benefit, and a favorable safety profile in adult patients with TRK fusion sarcomas with longer follow-up. These results continue to demonstrate that testing for NTRK gene fusions should be incorporated into the clinical management of adult patients with various types of sarcomas.

PLAIN LANGUAGE SUMMARY

Tropomyosin receptor kinase (TRK) fusion proteins result from translocations involving the NTRK gene and cause cancer in a range of tumor types. Larotrectinib is an agent that specifically targets TRK fusion proteins and is approved for the treatment of patients with TRK fusion cancer. This study looked at how well larotrectinib worked in adult patients with sarcomas caused by TRK fusion proteins. Over half of patients had a durable response to larotrectinib, with no unexpected side effects. These results show that larotrectinib is safe and effective in adult patients with TRK fusion sarcomas.

Economic Evaluation of a Tumour-Agnostic Therapy: Dutch Economic Value of Larotrectinib in TRK Fusion-Positive Cancers

BACKGROUND

Larotrectinib is the first tumour-agnostic therapy that has been approved by the European Medicines Agency. Tumour-agnostic therapies are indicated for a multitude of tumour types. The economic models supporting reimbursement submissions of tumour-agnostic therapies are complex because of the multitude of indications per model.

OBJECTIVE

The objective of this paper was to evaluate the cost effectiveness of larotrectinib compared with standard of care in patients with cancer with tropomyosin receptor kinase fusion-positive tumour types in the Netherlands.

METHODS

A previously constructed cost-effectiveness model with a partitioned survival approach was adapted to the Dutch setting, simulating costs and effects of treatment in patients with tropomyosin receptor kinase fusion-positive cancer. The cost-effectiveness model conducts a naïve comparison of larotrectinib to a weighted comparator standard-of-care arm. Dutch specific resource use and costs were implemented and inflated to reflect 2019 euros. The analysis includes a lifetime horizon and a societal perspective.

RESULTS

Larotrectinib versus Dutch standard of care resulted in 5.61 incremental (QALYs) and €232,260 incremental costs, leading to an incremental cost-effectivenes ratio of €41,424/QALY. The probabilistic sensitivity analysis reveals a 88% chance of larotrectinib being cost effective compared with the pooled comparator standard-of-care arm at the applicable €80,000/QALY willingness-to-pay threshold in the Netherlands.

CONCLUSIONS

The incremental cost-effectivenes ratio was well below the applicable threshold for diseases with a high burden of disease in the Netherlands (€80,000). At this threshold, larotrectinib was estimated to be a cost-effective treatment for patients with tropomyosin receptor kinase fusion-positive cancer compared with current standard of care in the Netherlands.

Clinical Trial Endpoints in Metastatic Cancer: Using Individual Participant Data to Inform Future Trials Methodology

Meta-analysis based on individual participant data (IPD) is a powerful methodology for synthesizing evidence by combining information drawn from multiple trials. Hitherto, its principal application has been in questions of clinical management, but an increasingly important use is in clarifying trials methodology, for instance in the selection of endpoints, as discussed in this review. In oncology, the Aide et Recherche en Cancérologie Digestive (ARCAD) Metastatic Colorectal Cancer Database is a leader in the use of IPD-based meta-analysis in methodological research. The ARCAD database contains IPD from more than 38 000 patients enrolled in 46 studies and continues to collect phase III trial data. Here, we review the principal findings of the ARCAD project in respect of endpoint selection and examine their implications for cancer trials. Analysis of the database has confirmed that progression-free survival (PFS) is no longer a valid surrogate endpoint predictive of overall survival in the first-line treatment of colorectal cancer. Nonetheless, PFS remains an endpoint of choice for most first-line trials in metastatic colorectal cancer and other solid tumors. Only substantial PFS effects are likely to translate into clinically meaningful benefits, and accordingly, we advocate an oncology research model designed to identify highly effective treatments in carefully defined patient groups. We also review the use of the ARCAD database in assessing clinical response including novel response metrics and prognostic markers. These studies demonstrate the value of IPD as a tool for methodological studies and provide a reference point for the expansion of this approach within clinical cancer research.

Clinical Trials of Liposomes in Children’s Anticancer Therapy: A Comprehensive Analysis of Trials Registered on ClinicalTrials.gov

Objective

Clinical trials have become essential for driving the development of medicine. However, little is known about the current status of clinical trials on liposomes in children’s anticancer therapy (LCAT). This study aimed to synthesize current finding from clinical trials of LCAT in ClinicalTrials.gov.

Methods

A cross-sectional descriptive study of clinical trials on LCAT was conducted, using studies registered on ClinicalTrials.gov through December 30, 2021.

Results

A total of 74 eligible trials were identified, accounting for 4.8% (74/1552) of all trials on liposomes for cancer therapy. Among these trials, 70 (94.6%) were interventional trials, and the remaining 4 (5.4%) were observational trials. Of the 70 interventional trials, 63 (90.0%) were for treatment, 48.6% were involving unlabeled allocations, 30.0% were randomized, 52.9% were single group assignment, 71.4% were without masking, 28.6% were Phase 3 trials, 30.0% were Phase 1 trials, and 24.3% were Phase 2 trials. Furthermore, 17 liposomal drugs for 123 types of cancer were investigated in the interventional trials, and these were mainly focused on organic chemicals (43/70, 61.4%). Of these cancers, the highest proportion was leukemia (15.4%), followed by lymphoma (9.8%) and ovarian cancer (8.9%).

Conclusion

High quality, adequately powered, masked, appropriately sized, and randomized clinical trials represent the critical priorities for conducting a high-quality clinical trial. However, most of these trials for LCAT were non-randomized, single group assignment, and non-blinded interventional trials of small scale, with various eligibility criteria and outcome measures. Our analysis highlights the need for improvement in the completeness of study designs curated on clinicalTrials.gov. We urge for decision-makers to avoid adopting entrenched positions about the study design of cancer clinical trials to avoid this problem. As such, tackling the problematic challenges related to cancer and designing efficient trials for cancer requires developing and applying new approaches and multiple strategies.

NTRK Fusion in Non-Small Cell Lung Cancer: Diagnosis, Therapy, and TRK Inhibitor Resistance

Neurotrophic tropomyosin receptor kinase (NTRK) gene fusion has been identified as an oncogenic driver of various solid tumors, and it is rare in non-smalll cell lung cancer (NSCLC) with a frequency of approximately less than 1%. Next-generation sequencing (NGS) is of priority for detecting NTRK fusions, especially RNA-based NGS. Currently, the tropomyosin receptor kinase (TRK) inhibitors have shown promising efficacy and well tolerance in patients with NTRK fusion-positive solid tumors, regardless of tumor histology. The first-generation TRK inhibitors (larotrectinib and entrectinib) are recommended as the first-line treatment for locally advanced or metastatic NSCLC patients with positive NTRK fusion. However, TRK inhibitor resistance can eventually occur due to on-target or off-target mechanisms. Further studies are under investigation to overcome resistance and improve survival. Interestingly, NTRK fusion might be the mechanism of resistance to epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKI) in NSCLC patients with EGFR mutation. Regarding immunotherapy, the efficacy of immune checkpoint inhibitors in NSCLC patients harboring NTRK fusion has yet to be well described. In this review, we elucidate the function of NTRK genes, summarize the diagnostic techniques for NTRK fusions, and present clinical data for TRK inhibitors; we also discuss potential mechanisms of resistance to TRK inhibitors.

Impact of tissue-agnostic approvals for patients with sarcoma

Tissue-agnostic drug development is a major step forward in offering treatment options for rare tumors. Sarcomas are heterogeneous rare malignancies with more than 100 subtypes. Recent failure of Phase III trials, nonbiomarker-driven clinical trials, and rarity hamper developmental therapeutics in sarcomas. Since a 'one-size-fits-all' approach continues to be the standard of care, tissue-agnostic approvals assume significance in sarcomas. In this review, we focus on the clinical evidence of recent drug approvals for neurotrophic tyrosine receptor kinase (NTRK) fusion, microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR) phenotype, and tumor mutation burden-high (TMB-H) status in the context of sarcomas, and the future landscape of tissue-agnostic targets, such as rearranged during transfection (RET), fibroblast growth factor receptor (FGFR), and neuregulin-1 (NRG1).

Belgian expert consensus for tumor-agnostic treatment of NTRK gene fusion-driven solid tumors with larotrectinib

Fusions of NTRK (neurotrophic tyrosine receptor kinase) genes with 5' partner genes can result in the expression of chimeric proteins that drive oncogenesis through ligand-independent kinase activation. Despite variable frequencies of NTRK fusions in different tumor types, the fact that they are common to a wide range of cancers raises the possibility of developing tumor-agnostic treatments specifically targeting NTRK fusion products, irrespective of tumor type. The first-generation Trk (tropomyosin receptor kinase) inhibitor, larotrectinib, was the first tumor-agnostic treatment of NTRK fusion-positive cancers in adults and children, to be approved in the European Union. This consensus, developed by a Belgian multidisciplinary expert panel, aims to highlight the unmet medical need associated to NTRK fusion-driven cancer treatment and, based on current knowledge of NTRK fusions and larotrectinib treatment outcome and safety, provide comprehensive guidance to oncologists regarding NTRK fusion-driven cancer diagnostics and the best use of larotrectinib in real-world clinical settings. Larotrectinib; NTRK gene fusion; Trk inhibitor; Tumor-agnostic; Expert opinion; Oncogene proteins; Protein kinase inhibitors.

Multi-omic molecular profiling guide's efficacious treatment selection in refractory metastatic breast cancer: a prospective phase II clinical trial

This prospective phase II clinical trial (Side Out 2) explored the clinical benefits of treatment selection informed by multi‐omic molecular profiling (MoMP) in refractory metastatic breast cancers (MBCs). Core needle biopsies were collected from 32 patients with MBC at trial enrollment. Patients had received an average of 3.94 previous lines of treatment in the metastatic setting before enrollment in this study. Samples underwent MoMP, including exome sequencing, RNA sequencing (RNA‐Seq), immunohistochemistry, and quantitative protein pathway activation mapping by Reverse Phase Protein Microarray (RPPA). Clinical benefit was assessed using the previously published growth modulation index (GMI) under the hypothesis that MoMP‐selected therapy would warrant further investigation for GMI ≥ 1.3 in ≥ 35% of the patients. Of the 32 patients enrolled, 29 received treatment based on their MoMP and 25 met the follow‐up criteria established by the trial protocol. Molecular information was delivered to the tumor board in a median time frame of 14 days (11–22 days), and targetable alterations for commercially available agents were found in 23/25 patients (92%). Of the 25 patients, 14 (56%) reached GMI ≥ 1.3. A high level of DNA topoisomerase I (TOPO1) led to the selection of irinotecan‐based treatments in 48% (12/25) of the patients. A pooled analysis suggested clinical benefit in patients with high TOPO1 expression receiving irinotecan‐based regimens (GMI ≥ 1.3 in 66.7% of cases). These results confirmed previous observations that MoMP increases the frequency of identifiable actionable alterations (92% of patients). The MoMP proposed allows the identification of biomarkers that are frequently expressed in MBCs and the evaluation of their role as predictors of response to commercially available agents. Lastly, this study confirmed the role of MoMP for informing treatment selection in refractory MBC patients: more than half of the enrolled patients reached a GMI ≥ 1.3 even after multiple lines of previous therapies for metastatic disease.

Targeting TRK: A fast-tracked application of precision oncology and future directions

The NTRK genes encode the tropomyosin-related receptor tyrosine kinases TrkA, TrkB and TrkC. TRK receptors regulate the proliferation, differentiation, and survival of many neuronal and non-neuronal glial cells during embryogenesis, thus playing a critical role in synaptic plasticity and the development of nociceptive pathways. Recurrent genomic alterations in NTRK genes, typically fusions involving the 3' region encoding the kinase domain juxtaposed to 5' sequences from numerous partner genes, occur at a low frequency in a wide diversity of adult and pediatric cancers. The contributions of the resulting constitutively activated kinase to oncogenesis and cancer progression are being elucidated. Larotrectinib and entrectinib are potent first-generation TRK inhibitors with IC₅₀ values in the nanomolar range across cancer cell lines harboring NTRK fusions. Larotrectinib is highly selective for TRK receptors, whereas entrectinib also potently inhibits ROS1 and ALK. Clinical trials of both drugs demonstrated significant and durable responses in patients with tumors harboring NTRK alterations, leading to first of its kind cancer agnostic FDA approvals in the United States for drugs targeting a genomic alteration. Unfortunately, acquired resistance inevitably develops. The second-generation TRK inhibitors selitrectinib and repotrectinib are designed to overcome known mechanisms of resistance.

Intrapatient comparisons of efficacy in a single-arm trial of entrectinib in tumour-agnostic indications

Background

Entrectinib is a tropomyosin receptor kinase inhibitor approved for the treatment of neurotrophic tyrosine receptor kinase (NTRK) fusion-positive solid tumours based on single-arm trials. Traditional randomised clinical trials in rare cancers are not feasible; we conducted an intrapatient analysis to evaluate the clinical benefit of entrectinib versus prior standard-of-care systemic therapies.

Methods

Patients with locally advanced/metastatic NTRK fusion-positive tumours enrolled in the global phase II, single-arm STARTRK-2 trial were grouped according to prior systemic therapy and response. The key analysis used growth modulation index [GMI; ratio of progression-free survival (PFS) on entrectinib to time to discontinuation (TTD) on the most recent prior therapy]; ratio ≥1.3 indicated clinically meaningful efficacy. Additional analyses investigated TTD and objective response rate (ORR) for entrectinib and prior therapies.

Results

Seventy-one patients were included; 51 received prior systemic therapy. In 38 patients who progressed on prior therapy, ORR was 60.5% (23/38) with entrectinib and 15.8% (6/38) with the most recent prior therapy. Median PFS [11.2 months; 95% confidence interval (CI) 6.7–not estimable] for entrectinib exceeded median TTD (2.9 months; 95% CI 2.0-4.9) for most recent prior therapy. From the intrapatient analysis of GMI, 65.8% had a ratio ≥1.3 and median GMI was 2.53. Consistent results were observed at more stringent GMI thresholds; 60.5% of patients had GMI ≥1.5 or ≥1.8 and 57.9% had GMI ≥2.0.

Conclusions

ORR was high and PFS was longer on entrectinib versus TTD on prior therapy. Furthermore, 65.8% of patients experienced clinically meaningful benefit based on GMI. This intrapatient analysis demonstrates comparative effectiveness of entrectinib in a rare, heterogeneous adult population.

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Randomised trials are unfeasible for molecular targeted agents in rare indications because of low patient numbers.

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Intrapatient comparison with prior therapies can be used to evaluate relative treatment efficacy in rare tumours.

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Entrectinib is a potent tropomyosin receptor kinase (TRK) inhibitor with proven efficacy in neurotrophic tyrosine receptor kinase (NTRK) fusion-positive tumours from the global STARTRK-2 trial.

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Median progression-free survival on entrectinib was longer than time to discontinuation on prior therapy (11.2 months versus 2.9 months).

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About 61% of patients with prior therapy progression responded to entrectinib; 66% had growth modulation index ≥1.3 (clinically meaningful threshold).