Early and Next-Generation KIT/PDGFRA Kinase Inhibitors and the Future of Treatment for Advanced Gastrointestinal Stromal Tumor

Effects of first‑line therapies in patients with locally advanced gastrointestinal stromal tumors with KIT and PDGFRα gene mutations: A single‑center study

Curative resection is typically recommended for treating gastrointestinal stromal tumors (GISTs). Exceptions are made for locally advanced GISTs (LAGISTs) where radical resection may be impossible. First-line imatinib therapy can be employed to treat GISTs harboring mutations in the tyrosine-protein kinase KIT (KIT) and platelet-derived growth factor receptor α (PDGFRα) genes to reduce the tumor size to resectable levels and minimize surgical risks. The present study investigated the treatment outcomes of patients with LAGISTs with different KIT and PDGFRα gene mutations who received first-line imatinib therapy. A total of 37 patients with LAGISTs who underwent first-line imatinib treatment were included, and the median follow-up period was 41 months. Treatment regimens included imatinib, with subsequent therapies, such as sunitinib and regorafenib, administered upon imatinib failure. The genetic profiles of KIT and PDGFRα were analyzed. Of the 37 patients, 24 (64.9%) successfully underwent curative resection. The median progression-free survival (PFS) was 36 months and the median overall survival (OS) was 41 months. Patients presented with tumors with various genetic mutations, which differentially affected their PFS and OS and adverse events were typically manageable. However, the gene mutation status was not significantly associated with treatment response or surgical resectability (both P>0.05). The present study elucidated the effects of first-line therapy on LAGISTs with genetic mutations, underscoring the effectiveness of imatinib treatment and the value of continual patient monitoring. Additional studies with long-term follow-up are required to evaluate treatment outcomes.

Characteristics and therapeutic strategies for familial gastrointestinal stromal tumors

This editorial discusses Wang et al's article on familial gastrointestinal stromal tumors (GISTs). We read with great interest this article concerning the diagnosis, treatment, and post-treatment management of patients with familial GISTs. The actual incidence of GISTs may be underestimated due to diagnostic limitations and the long-term low-risk behavior of some GISTs. The molecular landscape of GISTs is primarily driven by mutations in the KIT and platelet-derived growth factor receptor alpha (PDGFRA) genes. A subset of GISTs without these mutations known as wild-type GISTs, may harbor other rare mutations, impacting their response to targeted therapies. Clinically, patients with GISTs present with non-specific symptoms, often leading to delayed diagnosis. Genetic predispositions in familial GISTs provide insights into the genetic architecture and extragastrointestinal manifestations of GISTs. Management has evolved from surgical interventions to molecular-based therapies using tyrosine kinase inhibitors. The management of GISTs, especially in familial cases, requires a multidisciplinary approach. Cases of different gene mutations were reported in the same family, suggesting that incorporating genetic testing into routine clinical practice is crucial for the early identification of high-risk individuals and the implementation of tailored surveillance programs.

Clinical Significance of a Prospective Large Genomic Screening for SCLC: The Genetic Classification and a Biomarker-Driven Phase 2 Trial of Gedatolisib

INTRODUCTION

SCLC has been treated as a single entity resulting in limited survival improvement. Developing effective tools for guiding appropriate therapeutic strategies is crucial.

METHODS

A total of 1035 SCLCs were prospectively analyzed by a genomic screening platform: LC-SCRUM-Asia. Fresh frozen tumor samples were subjected to a next-generation sequencing system enabling the integrative analysis of cancer-related genes. A phase 2 trial of gedatolisib for SCLC with PI3K/AKT/mTOR pathway mutations was conducted based on this screening.

RESULTS

On the basis of the treatment outcomes and therapeutic targets, the following five distinct genetic subgroups were identified in SCLC: NSCLC-subgroup (genetic alterations associated with NSCLC, 8.5%); Hotspot-subgroup (targetable hotspot mutations common in tumors, 3.0%); PI3K-subgroup (PI3K/AKT/mTOR pathway mutations, 7.4%); MYC-subgroup (MYC family amplifications, 13.0%); and HME-subgroup (mutations in the histone-modifying enzymes, 17.6%). The NSCLC-subgroup (hazard ratio = 1.57; 95% confidence interval: 1.22-2.03) and MYC-subgroup (hazard ratio = 1.56; 95% confidence interval: 1.26-1.93) had significantly shorter progression-free survivals after first-line platinum-based treatment. The Hotspot-subgroup and MYC-subgroup were candidates for novel targeted therapies. The HME-subgroup had a favorable survival in patients who received programmed cell death (ligand) 1 inhibitor-based therapies (p = 0.005, log-rank test) regardless of some overlap with other subgroups. There were 15 patients enrolled into the phase 2 trial of gedatolisib in the PI3K-subgroup, and the overall response rate and the disease control rate were 6.7% and 20%, respectively. The MYC-subgroup or NSCLC-subgroup was associated with unfavorable clinical outcomes in this trial.

CONCLUSIONS

Molecular classification of SCLC by genetic approach is beneficial for predicting the treatment outcomes and effectively guiding the clinical choices.

Intracranial germ cell tumors: advancement in genomic diagnostics and the need for novel therapeutics

Introduction

The outcomes for patients with intracranial germ cell tumors (GCT) has improved over the past few decades. However, there remains a lack of a consensus on a standard diagnostic and treatment approach of these tumors. The diagnostic work-up of intracranial GCT remains variable, and the treatment for patients with recurrent disease remains challenging.

Methods

We review the current approach in the diagnosis and treatment of intracranial GCT. Given the heterogeneity of these tumors, we highlight the challenges and controversy with these conventional approaches.

Results

We discuss the advancements in the understanding of the underlying genetic changes in intracranial GCT and the utility of novel molecular techniques in the diagnosis and classification of intracranial germ cell tumors as well as development of potential novel therapeutics.

Discussion

Development of liquid biopsy platforms for diagnosis and management of malignancies is a rapidly growing field. Current approach utilizing traditional tumor markers have significant limitations. In this review, we will discuss profiling of intracranial GCTs for genetic and epigenetic signatures, which are emerging as promising biomarkers to assist in the diagnosis and management of intracranial GCTs. Various studies have shown that activating mutations in MAPK pathway are common alterations in intracranial GCTs, with KIT expression seen in most germinomas. Development of targeted therapeutics against KIT has led to the prospect of targeted therapy in germinoma. Other treatment modalities being considered for clinical development include immunotherapy and the use of immune checkpoint inhibitors, especially in NGGCT. In this review, we will discuss the potential novel therapeutics and the clinical trials that are currently under development.

Cancer-associated fibroblasts as therapeutic targets for cancer: advances, challenges, and future prospects

Research into cancer treatment has been mainly focused on developing therapies to directly target cancer cells. Over the past decade, extensive studies have revealed critical roles of the tumour microenvironment (TME) in cancer initiation, progression, and drug resistance. Notably, cancer-associated fibroblasts (CAFs) have emerged as one of the primary contributors in shaping TME, creating a favourable environment for cancer development. Many preclinical studies have identified promising targets on CAFs, demonstrating remarkable efficacy of some CAF-targeted treatments in preclinical models. Encouraged by these compelling findings, therapeutic strategies have now advanced into clinical evaluation. We aim to provide a comprehensive review of relevant subjects on CAFs, including CAF-related markers and targets, their multifaceted roles, and current landscape of ongoing clinical trials. This knowledge can guide future research on CAFs and advocate for clinical investigations targeting CAFs.

Discovery of novel PDGFR inhibitors targeting non-small cell lung cancer using a multistep machine learning assisted hybrid virtual screening approach

Non-Small Cell Lung Cancer (NSCLC) is a formidable global health challenge, responsible for the majority of cancer-related deaths worldwide. The Platelet-Derived Growth Factor Receptor (PDGFR) has emerged as a promising therapeutic target in NSCLC, given its crucial involvement in cell growth, proliferation, angiogenesis, and tumor progression. Among PDGFR inhibitors, avapritinib has garnered attention due to its selective activity against mutant forms of PDGFR, particularly PDGFRA D842V and KIT exon 17 D816V, linked to resistance against conventional tyrosine kinase inhibitors. In recent years, Machine Learning has emerged as a powerful tool in pharmaceutical research, offering data-driven insights and accelerating lead identification for drug discovery. In this research article, we focus on the application of Machine Learning, alongside the RDKit toolkit, to identify potential anti-cancer drug candidates targeting PDGFR in NSCLC. Our study demonstrates how smart algorithms efficiently narrow down large screening collections to target-specific sets of just a few hundred small molecules, streamlining the hit discovery process. Employing a Machine Learning-assisted virtual screening strategy, we successfully preselected 220 compounds with potential PDGFRA inhibitory activity from a vast library of 1.048 million compounds, representing a mere 0.013% of the original library. To validate these candidates, we employed traditional genetic algorithm-based virtual screening and docking methods. Remarkably, we found that ZINC000002931631 exhibited comparable or even superior inhibitory potential against PDGFRA compared to Avapritinib, which highlights the value of our Machine Learning approach. Moreover, as part of our lead validation studies, we conducted molecular dynamic simulations, revealing critical molecular-level interactions responsible for the conformational changes in PDGFRA necessary for substrate binding. Our study exemplifies the potential of Machine Learning in the drug discovery process, providing a more efficient and cost-effective means of identifying promising drug candidates for NSCLC treatment. The success of this approach in preselecting compounds with potent PDGFRA inhibitory potential highlights its significance in advancing personalized and targeted therapies for cancer treatment.

Identifying and validating angiogenesis-related genes remodeling tumor microenvironment and suppressing immunotherapy response in gastric cancer

Angiogenesis significantly correlates with tumor microenvironment remodeling and immunotherapy response. Our study aimed to construct a prognostic angiogenesis-related model for gastric cancer. Using public database, a angiogenetic related five-gene (FGF1, GRB14, PAK3, PDGFRA, and PRKD1) model was identified. The top 25 % of patients were defined as high-risk, and the remaining as low-risk. The area under the curve for 1-, 3-, and 5-year overall survival (OS) were 0.646, 0.711, and 0.793, respectively. Survival analysis showed a better 10-year OS in low-risk patients in the construction (HR = 0.57, p = 0.002) and validation cohorts. GO and GSEA revealed that DEGs were enriched in extracellular matrix receptor interactions, dendritic cell antigen processing/presentation regulation, and angiogenesis pathways. CIBERSORT analysis revealed abundant naïve B cells, resting mast cells, resting CD4+ memory T cells, M2 macrophages, and monocytes in high-risk subgroups. The TIMER database showed strong positive correlations between PAK3, FGF1, PRKD1, and PDGFRA expression levels and the infiltration of CD4+ T cells and macrophages. The IOBR analysis revealed an immunosuppressive environment in the high-risk subgroup. Low-risk patients show a higher response rate to anti-PD1 treatment. TMA showed that FGF1 overexpression was associated with poor prognosis and CD4+ T cells and macrophage infiltration. In vivo study based on the 615 mice indicated that inhibiting FGF1 function could suppress tumor growth and enhance anti-PD1 therapeutic efficacy. In summary, we established a five-angiogenesis-related gene model to predict survival outcomes and immunotherapy responses in patients with gastric cancer and identified FGF1 as a prognostic gene and potential target for improving immune treatment.

The INSIGHT study: a randomized, Phase III study of ripretinib versus sunitinib for advanced gastrointestinal stromal tumor with KIT exon 11 + 17/18 mutations

Somatic KIT activating mutations drive most gastrointestinal stromal tumors (GISTs). Disease progression eventually develops with first-line imatinib, commonly due to KIT secondary mutations, and different kinase inhibitors have various levels of treatment efficacy dependent on specific acquired resistance mutations. Ripretinib is a broad-spectrum switch-control KIT/PDGFRA tyrosine kinase inhibitor for patients with advanced GIST who received prior treatment with three or more kinase inhibitors, including imatinib. Exploratory baseline circulating tumor DNA analysis from the second-line INTRIGUE trial determined that patients with advanced GIST previously treated with imatinib harboring primary KIT exon 11 mutations and secondary resistance mutations restricted to KIT exons 17/18 had greater clinical benefit with ripretinib versus sunitinib. We describe the rationale and design of INSIGHT (NCT05734105), an ongoing Phase III open-label study of ripretinib versus sunitinib in patients with advanced GIST previously treated with imatinib exclusively harboring KIT exon 11 + 17/18 mutations detected by circulating tumor DNA.Clinical Trial Registration: NCT05734105 (ClinicalTrials.gov).

Effect and safety of ripretinib in the treatment of advanced gastrointestinal stromal tumor: A systematic review and meta-analysis

BACKGROUND

Imatinib (IMA) has received approval as the primary treatment for gastrointestinal stromal tumors (GIST). Nonetheless, approximately half of the patients with advanced GIST show disease advancement following IMA treatment. Presently, the efficacy of secondary and tertiary medications in addressing various GIST secondary mutations is somewhat restricted. Consequently, there is a significant medical demand for the creation of kinase inhibitors that extensively block secondary drug-resistant mutations in advanced GIST. Ripretinib (RPT) is a new, switch-control tyrosine kinase inhibitors that can suppress different mutations of KIT and PDGFRA via a dual mechanism of action.

AIM

To investigate the literature on RPT to assess an effective, safe, and successful treatment strategy against advanced GIST.

METHODS

The present systematic review and meta-analysis was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. PubMed, Embase, Cochrane, Web of Science and ClinicalTrials.gov databases were screened from January 1, 2003 to May 1, 2024.

RESULTS

A total of 4 studies were included, with a total of 507 patients enrolled. The objective response rate (ORR) of the RPT-treated advanced GIST was 17% (95%CI: 0.11-0.27), while the disease control rate (DCR) was 66% (95%CI: 0.59-0.73). The overall occurrence of adverse events with varying degrees was 97% (95%CI: 0.93-1), whereas that of grade ≥ 3 adverse reactions was 42% (95%CI: 0.28-0.63). The sensitivity analysis revealed that omitting some studies did not yield statistically notable variances in the aggregate data regarding the ORR, DCR, and the occurrence of adverse events of grade 3 or higher. The publication bias was absent because no significant asymmetry was observed in Begg's funnel plot in all studies.

CONCLUSION

RPT has favorable efficacy profiles in GIST patients, but the adverse reactions are obvious, and patient management needs to be strengthened to achieve better safety and tolerability.

Natural Alkaloids in Cancer Therapy: Berberine, Sanguinarine and Chelerythrine against Colorectal and Gastric Cancer

The rising incidence of colorectal cancer (CRC) and gastric cancer (GC) worldwide, coupled with the limited effectiveness of current chemotherapeutic agents, has prioritized the search for new therapeutic options. Natural substances, which often exhibit cytostatic properties, hold significant promise in this area. This review evaluates the anticancer properties of three natural alkaloids-berberine, sanguinarine, and chelerythrine-against CRC and GC. In vivo and in vitro studies have demonstrated that these substances can reduce tumor volume and inhibit the epithelial-mesenchymal transition (EMT) of tumors. At the molecular level, these alkaloids disrupt key signaling pathways in cancer cells, including mTOR, MAPK, EGFR, PI3K/AKT, and NF-κB. Additionally, they exhibit immunomodulatory effects, leading to the induction of programmed cell death through both apoptosis and autophagy. Notably, these substances have shown synergistic effects when combined with classical cytostatic agents such as cyclophosphamide, 5-fluorouracil, cetuximab, and erlotinib. Furthermore, berberine has demonstrated the ability to restore sensitivity in individuals originally resistant to cisplatin GC. Given these findings, natural compounds emerge as a promising option in the chemotherapy of malignant gastrointestinal tumors, particularly in cases with limited treatment options. However, more research is necessary to fully understand their therapeutic potential.

Survival of advanced/recurrent gastrointestinal stromal tumors treated with tyrosine kinase inhibitors in Taiwan: a nationwide registry study

BACKGROUND

Most gastrointestinal stromal tumors (GISTs) harbor c-KIT or PDGFRA mutations. Administration of tyrosine kinase inhibitors (TKIs) has significantly improved the survival of patients with GISTs. We aimed to evaluate the clinical outcome of advanced or recurrent GIST patients in Taiwan.

METHODS

Patients diagnosed between 2010 and 2020 were enrolled. The collected data included baseline characteristics, treatment pattern, treatment outcome, genetic aberrations and survival status. Progression-free survival (PFS) and overall survival (OS) were analyzed and plotted with the Kaplan-Meier method. Cox regression analysis was used to analyze the prognostic factors of survival.

RESULTS

A total of 224 patients with advanced or recurrent GISTs treated with TKIs were enrolled. All patients received imatinib treatment. Ninety-three and 42 patients received sunitinib and regorafenib treatment, respectively. The 48-month PFS and OS rates for patients treated with imatinib were 50.5% and 79.5%, respectively. c-KIT exon 9 and PDGFRA mutations were prognostic factors for a poor PFS and PDGFRA mutation was a prognostic factor for a poor OS in patients treated with imatinib in multivariate Cox regression analysis. The median PFS of patients who received sunitinib treatment was 12.76 months (95% confidence interval (CI), 11.01-14.52). Patients with c-KIT exon 9 mutations had a longer PFS than those with other genetic aberrations. The median PFS of patients treated with regorafenib was 7.14 months (95% CI, 3.39-10.89).

CONCLUSIONS

We present real-world clinical outcomes for advanced GIST patients treated with TKIs and identify mutational status as an independent prognostic factor for patient survival.

Precision Oncology in Soft Tissue Sarcomas and Gastrointestinal Stromal Tumors

Soft tissue sarcomas (STSs), including gastrointestinal stromal tumors (GISTs), are mesenchymal neoplasms with heterogeneous clinical behavior and represent broad categories comprising multiple distinct biologic entities. Multidisciplinary management of these rare tumors is critical. To date, multiple studies have outlined the importance of biological characterization of mesenchymal tumors and have identified key molecular alterations which drive tumor biology. GIST has represented a flagship for targeted therapy in solid tumors with the advent of imatinib which has revolutionized the way we treat this malignancy. Herein, the authors discuss the importance of biological and molecular diagnostics in managing STS and GIST patients.

Referral patterns of GIST patients: data from a nationwide study

BACKGROUND

This study compares the characteristics, referral and treatment patterns and overall survival (OS) of gastrointestinal stromal tumor (GIST) patients treated in reference and non-reference centers in the Netherlands.

PATIENTS AND METHODS

This retrospective cohort study on patients diagnosed between 2016 and 2019, utilises data from the Netherlands Cancer Registry and the Dutch Nationwide Pathology Database. Patients were categorized into two groups: patients diagnosed in or referred to reference centers and patients diagnosed in non-reference centers without referral.

RESULTS

This study included 1,550 GIST patients with a median age of 67.0 in reference and 68.0 years in non-reference centers. Eighty-seven per cent of patients were diagnosed in non-reference centers, of which 36.5% (493/1,352) were referred to a reference center. Referral rates were higher for high-risk (62.2% [74/119]) and metastatic patients (67.2% [90/134]). Mutation analysis was performed in 96.9% and 87.6% of these cases in reference and in non-reference centers (p < 0.01), respectively. Systemic therapy was given in reference centers versus non-reference in 89.5% versus 82.0% (p < 0.01) of high-risk and in 94.1% versus 65.9% (p < 0.01) of metastatic patients, respectively. The proportion of positive resection margins and tumor rupture did not differ between reference and non-reference centers. Median OS was not reached.

CONCLUSION

A substantial amount of metastatic GIST patients in non-reference centers did not receive systemic treatment. This might be due to valid reasons. However, optimisation of the referral strategy of GIST patients in the Netherlands could benefit patients. Further research is needed to explore reasons for not starting systemic treatment in metastatic GIST patients.

Avapritinib-based SAR studies unveil a binding pocket in KIT and PDGFRA

Avapritinib is the only potent and selective inhibitor approved for the treatment of D842V-mutant gastrointestinal stromal tumors (GIST), the most common primary mutation of the platelet-derived growth factor receptor α (PDGFRA). The approval was based on the NAVIGATOR trial, which revealed overall response rates of more than 90%. Despite this transformational activity, patients eventually progress, mostly due to acquired resistance mutations or following discontinuation due to neuro-cognitive side effects. These patients have no therapeutic alternative and face a dismal prognosis. Notable, little is known about this drug's binding mode and its medicinal chemistry development, which is instrumental for the development of the next generation of drugs. Against this background, we solve the crystal structures of avapritinib in complex with wild-type and mutant PDGFRA and stem cell factor receptor (KIT), which provide evidence and understanding of inhibitor binding and lead to the identification of a sub-pocket (Gα-pocket). We utilize this information to design, synthesize and characterize avapritinib derivatives for the determination of key pharmacophoric features to overcome drug resistance and limit potential blood-brain barrier penetration.

Efficacy and safety of ripretinib vs. sunitinib in patients with advanced gastrointestinal stromal tumor previously treated with imatinib: A phase 2, multicenter, randomized, open-label study in China

AIM

A bridging study of INTRIGUE study to assess the efficacy and safety of ripretinib versus sunitinib as second-line treatment in Chinese GIST patients.

METHODS

This was a phase 2, multicenter, randomized, open-label study in China. GIST patients previously treated with imatinib were randomized (1:1) to receive ripretinib 150 mg once daily (QD) by continuous dosing in 42-day cycles or sunitinib 50 mg QD in 42-day cycles (four weeks on/two weeks off). Primary endpoint was progression-free survival (PFS) by independent radiological review (IRR).

RESULTS

Between 6 December 2020 and 15 September 2021, 108 patients were randomized to receive ripretinib (n = 54) or sunitinib (n = 54) (all-patient [AP] intention-to-treat [ITT] population). Seventy patients had primary KIT exon 11 mutations (ripretinib, n = 35; sunitinib, n = 35; Ex11 ITT population). By data cut-off (20 July 2022), in AP ITT population, PFS by IRR was comparable between ripretinib and sunitinib arms (HR 0·99, 95 % CI 0·57, 1·69; nominal p = 0·92; median PFS [mPFS] 10·3 vs 8·3 months). In Ex11 ITT population, PFS by IRR was longer for ripretinib than sunitinib (HR 0·46, 95 % CI 0·23, 0·92; nominal p = 0·03; mPFS not reached in ripretinib arm and 4·9 months in sunitinib arm). Fewer patients experienced grade 3/4 treatment-related treatment-emergent adverse events with ripretinib (17%) versus sunitinib (56%).

CONCLUSIONS

Ripretinib demonstrated similar efficacy and a favorable safety profile versus sunitinib as second-line treatment in Chinese GIST patients. Furthermore, ripretinib provided greater clinically meaningful benefit versus sunitinib in patients with KIT exon 11 mutation.

Sarcoma care in the era of precision medicine

Sarcoma subtype classification is currently mainly based upon histopathological morphology. Molecular analyses have emerged as an efficient addition to the diagnostic workup and sarcoma care. Knowledge about the sarcoma genome increases, and genetic events that can either support a histopathological diagnosis or suggest a differential diagnosis are identified, as well as novel therapeutic targets. In this review, we present diagnostic, therapeutic, and prognostic molecular markers that are, or might soon be, used clinically. For sarcoma diagnostics, there are specific fusions highly supportive or pathognomonic for a diagnostic entity-for instance, SYT::SSX in synovial sarcoma. Complex karyotypes also give diagnostic information-for example, supporting dedifferentiation rather than low-grade central osteosarcoma or well-differentiated liposarcoma when detected in combination with MDM2/CDK4 amplification. Molecular treatment predictive sarcoma markers are available for gastrointestinal stromal tumor (GIST) and locally aggressive benign mesenchymal tumors. The molecular prognostic markers for sarcomas in clinical practice are few. For solitary fibrous tumor, the type of NAB2::STAT6 fusion is associated with the outcome, and the KIT/PDGFRA pathogenic variant in GISTs can give prognostic information. With the exploding availability of sequencing technologies, it becomes increasingly important to understand the strengths and limitations of those methods and their context in sarcoma diagnostics. It is reasonable to believe that most sarcoma treatment centers will increase the use of massive-parallel sequencing soon. We conclude that the context in which the genetic findings are interpreted is of importance, and the interpretation of genomic findings requires considering tumor histomorphology.

A review: FDA-approved fluorine-containing small molecules from 2015 to 2022

Fluorine-containing small molecules have occupied a special position in drug discovery research. The successful clinical use of fluorinated corticosteroids in the 1950s and fluoroquinolones in the 1980s led to an ever-increasing number of approved fluorinated compounds over the last 50 years. They have shown various biological properties such as antitumor, antimicrobial, and anti-inflammatory activities. Fluoro-pharmaceuticals have been considered a strong and practical tool in the rational drug design approach due to their benefits from potency and ADME (absorption, distribution, metabolism, and excretion) points of view. Herein, approved fluorinated drugs from 2015 to 2022 were reviewed.

A phase II study on the efficacy of regorafenib in treating patients with c-KIT-mutated metastatic malignant melanoma that progressed after previous treatment (KCSG-UN-14-13)

BACKGROUND

c-KIT mutations are found in approximately 15% of patients with malignant melanoma in the Asian population. Regorafenib, an oral multikinase inhibitor, acts against both wild-type and mutant KIT.

OBJECTIVE

This multi-institutional, phase II, single-arm study aimed to evaluate the efficacy of regorafenib against metastatic malignant melanoma harbouring c-KIT mutations.

METHODS

Patients with metastatic melanoma positive for c-KIT mutations, upon progression after at least one line of systemic treatment, were enroled. Patients received oral regorafenib 160 mg once daily for 3 weeks (4-week cycle). The primary endpoint was disease control rate (DCR), and secondary endpoints were safety, overall response rate (ORR), progression-free survival (PFS), and overall survival (OS).

RESULTS

In total, 23 patients were enrolled. c-KIT mutations were frequently reported in exon 11 (14/23, 60.9%), followed by exons 13, 17, and 9 in 5 (21.7%), 5 (21.7%), and 2 (8.7%) patients, respectively. DCR at 8 weeks was 73.9%, with 2 patients (8.7%) achieving complete response, 5 (21.7%) achieving partial response, and 10 (43.5%) showing stable disease. ORR was 30.4% (7/23). The median follow-up period was 15.7 months (95% confidence interval [CI], 9.6-21.3), and median OS and PFS were 21.5 months (95% CI, 15.1-27.9) and 7.1 months (95% CI, 5.0-9.2), respectively. Circulating tumour DNA analysis in selected patients showed high c-KIT correlation (85.7%) with tissue-based tumour mutational profiles. The most common adverse events (AEs) were skin reactions, including palmar-plantar erythrodysesthesia (52.2%), and grade 3 AEs were reported in 39.1% (9/23) of the patients.

CONCLUSION

Regorafenib in second- or later-line settings demonstrated significant activity in patients with metastatic melanoma harbouring c-KIT mutations.

Ripretinib in combination with tyrosine kinase inhibitor as a late-line treatment option for refractory gastrointestinal stromal tumors: two case reports and literature review

Background: This case report presents two clinical cases of metastatic refractory gastrointestinal stromal tumor (GIST) with treatment history of 6-14 years. The follow-up treatment of both cases comprised ripretinib dose escalation and its combination with other tyrosine kinase inhibitors (TKIs). To the best of our knowledge, this is the first report that explored ripretinib combination therapy in the late-line treatment of GISTs. Case description: Case-1 represents a 57-year-old female patient who underwent surgical resection for retroperitoneal GIST in 2008. After tumor recurrence in 2009, imatinib was started with complete response for 8 years. Imatinib was followed by sunitinib and regorafenib treatment. In March 2021, due to progressive disease (PD), the patient started ripretinib (150 mg QD) and achieved partial response (PR). Six months later, the patient showed PD. Subsequently, ripretinib dose was increased (150 mg BID) followed by ripretinib (100 mg QD) and imatinib (200 mg QD) combination. CT performed in February 2022 revealed stable lesions with internal visible necrosis. Combination therapy achieved stable disease (SD) for 7 months. On further follow-up in July 2022, the patient showed PD and died in September 2022. Case-2: represents a 73-year-old female patient diagnosed with unresectable duodenal GIST with liver, lung, and lymph node metastases in 2016. After treatment with imatinib, followed by sunitinib, regorafenib, and imatinib rechallenge, ripretinib (150 mg QD) was administered in May 2021, and SD was achieved. Ripretinib dose was increased (200 mg QD) due to PD in December 2021. The tumor showed heterogeneous manifestations, with overall size increase and regression in right posterior lobe. In February 2022, ripretinib (150 mg) plus sunitinib (25 mg) QD was commenced. On follow-up in April 2022, the patient showed slightly improved symptoms with stable hematologic parameters. Combination therapy achieved SD for 5 months and the patient showed PD in July 2022 and discontinued the treatment later. The patient was in poor general condition and was receiving nutritional therapy until last follow-up in October 2022. Conclusion: This case report provides evidence that combination therapy of ripretinib with other TKIs could be an effective late-line treatment option for refractory GIST patients.

Efficacy and safety of ripretinib in Chinese patients with advanced gastrointestinal stromal tumors: a real-world, multicenter, observational study

Introduction

Mutations in KIT proto-oncogene, receptor tyrosine kinase (KIT) and platelet-derived growth factor receptor-α (PDGFRA) render the available tyrosine kinase inhibitors (TKI) ineffective in treating advanced gastrointestinal stromal tumors (GIST). Ripretinib, a broad-spectrum switch-control kinase inhibitor, has shown increased efficacy and manageable safety, but real-world evidence remains scarce. This study evaluates the efficacy and safety of ripretinib among Chinese patients in a real-world setting.

Methods

Advanced GIST patients (N=23) receiving ripretinib following progression on previous lines of TKI treatment were enrolled to determine the efficacy [progression-free survival (PFS) and overall survival (OS)]. Safety was assessed by the incidence and severity of adverse events (AEs). All statistical analyses were performed using SPSS version 20.0 and a p-value of <0.05 was considered significant.

Results

The median PFS (mPFS) of efficacy analysis set (EAS) (N=21) was 7.1 months. mPFS of patients receiving ripretinib following ≤2 lines of previous TKI treatment and ≥3 prior lines of therapy were 7.1 and 9.2 months, respectively. The median OS (mOS) was 12.0 months and shorter interval between the end of the latest TKI and ripretinib therapy was correlated with longer median PFS and OS (p=0.054 and p=0.046), respectively. Alopecia and asthenia were the most common AEs observed.

Conclusion

Compared to previous lines of TKI in advanced GIST patients, ripretinib showed superior efficacy with clinically manageable AEs. Real-world results are comparable to that of phase III INVICTUS study and its Chinese bridging study. Hence, ripretinib can be used for the clinical management of advanced GIST patients.

Receptor tyrosine kinase inhibitors in cancer

Targeted therapy is a new cancer treatment approach, involving drugs that particularly target specific proteins in cancer cells, such as receptor tyrosine kinases (RTKs) which are involved in promoting growth and proliferation, Therefore inhibiting these proteins could impede cancer progression. An understanding of RTKs and the relevant signaling cascades, has enabled the development of many targeted drug therapies employing RTK inhibitors (RTKIs) some of which have entered clinical application. Here we discuss RTK structures, activation mechanisms and functions. Moreover, we cover the potential effects of combination drug therapy (including chemotherapy or immunotherapy agents with one RTKI or multiple RTKIs) especially for drug resistant cancers.

Neuropsychiatric Adverse Drug Reactions with Tyrosine Kinase Inhibitors in Gastrointestinal Stromal Tumors: An Analysis from the European Spontaneous Adverse Event Reporting System

Tyrosine kinase inhibitors (TKIs) are widely used in gastrointestinal stromal tumors (GISTs). The aim of this study is to evaluate the reporting frequency of neuropsychiatric adverse drug reactions (ADRs) for TKIs through the analysis of European individual case safety reports (ICSRs). All ICSRs collected in EudraVigilance up to 31 December 2021 with one TKI having GISTs as an indication (imatinib (IM), sunitinib (SU), avapritinib (AVA), regorafenib (REG), and ripretinib (RIP)) were included. A disproportionality analysis was performed to assess the frequency of reporting for each TKI compared to all other TKIs. The number of analyzed ICSRs was 8512, of which 57.9% were related to IM. Neuropsychiatric ADRs were reported at least once in 1511 ICSRs (17.8%). A higher reporting probability of neuropsychiatric ADRs was shown for AVA. Most neuropsychiatric ADRs were known, except for a higher frequency of lumbar spinal cord and nerve root disorders (reporting odds ratio, ROR 4.46; confidence interval, CI 95% 1.58–12.54), olfactory nerve disorders (8.02; 2.44–26.33), and hallucinations (22.96; 8.45–62.36) for AVA. The analyses of European ICSRs largely confirmed the safety profiles of TKIs in GISTs, but some ADRs are worthy of discussion. Further studies are needed to increase the knowledge of the neuropsychiatric disorders of newly approved TKIs.

Identification of M4205─A Highly Selective Inhibitor of KIT Mutations for Treatment of Unresectable Metastatic or Recurrent Gastrointestinal Stromal Tumors

The treatment of gastrointestinal stromal tumors (GISTs) driven by activating mutations in the KIT gene is a prime example of targeted therapy for treatment of cancer. The approval of the tyrosine kinase inhibitor imatinib has significantly improved patient survival, but emerging resistance under treatment and relapse is observed. Several additional KIT inhibitors have been approved; still, there is a high unmet need for KIT inhibitors with high selectivity and broad coverage of all clinically relevant KIT mutants. An imidazopyridine hit featuring excellent kinase selectivity was identified in a high-throughput screen (HTS) and optimized to the clinical candidate M4205 (IDRX-42). This molecule has a superior profile compared to approved drugs, suggesting a best-in-class potential for recurrent and metastatic GISTs driven by KIT mutations.

Emerging Data on the Safety and Efficacy of Ripretinib for the Treatment of Gastrointestinal Stromal Tumors

In patients with gastrointestinal stromal tumors (GIST), systemic treatment after disease progression on imatinib is challenging. Sunitinib and regorafenib are approved in the second- and third-line setting, respectively, with activity against certain secondary mutations with comparatively much lower response rates and survival increment compared to imatinib. All three of these drugs were serendipitously found to have activity in GIST, starting with imatinib, which was formulated for its ability to inhibit BCR-ABL in chronic myelogenous leukemia. Ripretinib is a drug that was specifically developed as a more potent KIT tyrosine kinase inhibitor (TKI), with broad-spectrum activity against the mutations encountered in GIST. Encouraging responses in early and later lines of treatment in the Phase 1 trial of ripretinib in GIST led to the rapid development of this novel drug. In a Phase 3 randomized clinical trial with cross-over, ripretinib demonstrated superior PFS and overall survival (OS) in 4th-line treatment and beyond compared to placebo. This established 150 mg once daily ripretinib as the standard of care in this setting. Ripretinib is generally well tolerated, with common adverse effects of hair loss, diarrhea, cramps, fatigue and nausea. The favorable safety profile and efficacy of ripretinib prompted its evaluation in a randomized phase 3 trial in the 2nd-line treatment setting. However, it did not result in a longer PFS duration than sunitinib. Although the efficacy of ripretinib in this unselected patient population was not significantly different from that of sunitinib, the tolerability profile was better. This review article aims to review the efficacy and tolerability profile of ripretinib, together with its role in the setting of unresectable or metastatic GIST.

Insights into the medical management of gastrointestinal stromal tumours: lessons learnt from a dedicated gastrointestinal stromal tumour clinic in North India

Background

The advent of molecular driver alterations has brought in a revolutionary transformation in the treatment landscape of gastrointestinal stromal tumour (GIST). However, there is a paucity of data regarding mutational testing prevalence and associated outcomes from India.

Methods

It was a retrospective study. We reviewed the case records of all patients diagnosed with GIST in a tertiary care centre from 2015 to 2021. The clinicopathological, mutational analysis and treatment plans were recorded. The study cohort was characterised by descriptive statistics.

Results

Our study included 120 patients with a median age of 53 years (range: 28-77), with a male preponderance of 2:1. The most common site of the primary was the stomach (50%), followed by the small intestine (37%), with 55.8% of the patients having disseminated disease at presentation with a predominance of liver metastasis (67%). The prevalence of mutational analysis among patients prior to referral was 4%. 60.8% of the patients at our clinic had mutational analysis performed, and unavailability of analysis in the rest was due to financial constraints (12.5%), exhaustion of tissue (7.5%), reluctance to repeat biopsy (4.1%) and low-risk patients. We report c-kit in the majority (52%), platelet-derived growth factor receptor (PDGFR) in 19.2% and wild type in 16.4% along with the rarer subtypes: succinate dehydrogenase (SDH)-deficient GIST in 10.9% and Neurotrophic tyrosine receptor kinase (NTRK) fusion in 1.3%. Four of the eight SDH-deficient GIST patients had germline mutations (50%). The knowledge of driver mutations led to a change of treatment in 39.7% (29/73), i.e. stoppage of tyrosine kinase inhibitor (TKI) in 3, switch of TKI in 23, increase in TKI dose in 2 and upfront surgery in 1. The most common change was the use of sunitinib and regorafenib in patients with SDH-deficient GIST.

Conclusion

Our study is one of the largest comprehensive series describing the clinical and mutational profile of GIST from India. The mutation testing rates at primary care centres continue to be low. Despite the hurdles, a large percentage of our patients underwent molecular testing, aiding in therapeutic decision-making.

New natural compound inhibitors of PDGFRA (platelet-derived growth factor receptor α) based on computational study for high-grade glioma therapy

BACKGROUND

High-grade glioma (HGG) is a malignant brain tumor that is common and aggressive in children and adults. In the current medical paradigm, surgery and radiotherapy are the standard treatments for HGG patients. Despite this, the overall prognosis is still very bleak. Studies have shown that platelet-derived growth factor receptor α (PDGFRA) is an essential target to treat tumors and inhibiting the activity of PDGFRA can improve the prognosis of HGG. Thus, PDGFRA inhibitors are critical to developing drugs and cancer treatment.

OBJECTIVE

The purpose of this study was to screen lead compounds and candidate drugs with potential inhibitors against platelet-derived growth factor receptor α (PDGFRA) from the drug library (ZINC database) in order to improve the prognosis of patients with high-grade glioma (HGG).

MATERIALS AND METHODS

In our study, we selected Imatinib as the reference drug. A series of computer-aided technologies, such as Discovery Studio 2019 and Schrodinger, were used to screen and assess potential inhibitors of PDGFRA. The first step was to calculate the LibDock scores and then analyze the pharmacological and toxicological properties. Following this, we docked the small molecules selected in the previous steps with PDGFRA to study their docking mechanism and affinity. In addition, molecular dynamics simulation was used to determine whether the ligand-PDGFRA complex was stable in nature.

RESULTS

Two novel natural compounds 1 and 2 (ZINC000008829785 and ZINC000013377891) from the ZINC database were found binding to PDGFRA with more favorable interaction energy. Also, they were predicted with less Ames mutagenicity, rodent carcinogenicity, non-developmental toxic potential, and tolerant with cytochrome P450 2D6 (CYP2D6). The dynamic simulation analysis demonstrated that ZINC000008829785-PDGFRA and ZINC000013377891-PDGFRA dimer complex had more favorable potential energy compared with Imatinib, and they can exist in natural environments stably.

CONCLUSION

ZINC000008829785 and ZINC000013377891 might provide a solid foundation for drugs that inhibit PDGFRA in HGG. In addition to being safe drug candidates, these compounds had important implications for improving drugs targeting PDGFRA.

Multiple Metastatic Extra-gastrointestinal Stromal Tumors with Plasmoid Differentiation: A Case Report and Review of Literature

Extra-gastrointestinal stromal tumors (EGISTs) are rare mesenchymal tumors that arise from the abdominal, pelvic or retroperitoneal region, unrelated to the gastrointestinal tract. However, cases with a plasmoid morphology are extremely rare. we hererin report a 49-year-old man with abdominal pain who underwent magnetic resonance imaging that revealed an irregular tumor (103×71 mm) in size, in the space between stomach and pancreas, diagnosed as an EGISIT, we also reviewed the clinicopathological characteristics and immunohistochemical characteristics, molecular genetic features and differential diagnoses previously reported in the literature.

Advances of endoscopic and surgical management in gastrointestinal stromal tumors

As one of the most common mesenchymal malignancies in the digestive system, gastrointestinal stromal tumors (GISTs) occur throughout the alimentary tract with diversified oncological characteristics. With the advent of the tyrosine kinase inhibitor era, the treatment regimens of patients with GISTs have been revolutionized and GISTs have become the paradigm of multidisciplinary therapy. However, surgery resection remains recognized as the potentially curative management for the radical resection and provided with favorable oncological outcomes. The existing available surgery algorithms in clinical practice primarily incorporate open procedure, and endoscopic and laparoscopic surgery together with combined operation techniques. The performance of various surgery methods often refers to the consideration of risk evaluation of recurrence and metastases; the degree of disease progression; size, location, and growth pattern of tumor; general conditions of selected patients; and indications and safety profile of various techniques. In the present review, we summarize the fundamental principle of surgery of GISTs based on risk assessment as well as tumor size, location, and degree of progress with an emphasis on the indications, strengths, and limitations of current surgery techniques.

Latest Advances in the Management of Pediatric Gastrointestinal Stromal Tumors

Gastrointestinal stromal tumor is the most common mesenchymal neoplasm of the gastrointestinal tract, usually found in elderly adults. It is infrequent among pediatric patients and usually differs biologically from adult-type diseases presenting mutations of KIT and PDGFR genes. In this population, more frequent is the wild-type GIST possessing SDH, TRK, RAS, NF1 mutations, among others. Both tumor types require individualized treatment with kinase inhibitors that are still being tested in the pediatric population due to the different neoplasm biology. We review the latest updates to the management of pediatric gastrointestinal tumors with a particular focus on the advances in molecular biology of the disease that enables the definition of possible resistance. Emerging treatment with kinase inhibitors that could serve as targeted therapy is discussed, especially with multikinase inhibitors of higher generation, the effectiveness of which has already been confirmed in the adult population.

Molecular targeted therapy for anticancer treatment

Since the initial clinical approval in the late 1990s and remarkable anticancer effects for certain types of cancer, molecular targeted therapy utilizing small molecule agents or therapeutic monoclonal antibodies acting as signal transduction inhibitors has served as a fundamental backbone in precision medicine for cancer treatment. These approaches are now used clinically as first-line therapy for various types of human cancers. Compared to conventional chemotherapy, targeted therapeutic agents have efficient anticancer effects with fewer side effects. However, the emergence of drug resistance is a major drawback of molecular targeted therapy, and several strategies have been attempted to improve therapeutic efficacy by overcoming such resistance. Herein, we summarize current knowledge regarding several targeted therapeutic agents, including classification, a brief biology of target kinases, mechanisms of action, examples of clinically used targeted therapy, and perspectives for future development.

Clinical and NGS predictors of response to regorafenib in recurrent glioblastoma

Predictive factors for response to regorafenib in recurrent glioblastoma, IDH-wildtype, are scarcely recognized. The objective of this study was to identify molecular predictive factors for response to regorafenib using a clinically available platform. We analyzed a prospective cohort of 30 patients harboring recurrent glioblastoma, IDH-wildtype, and treated with regorafenib. Next-generation sequencing (NGS) analysis was performed on DNA extracted from paraffin-embedded tissues using a clinically available platform. Moreover, MGMT methylation and EGFRvIII expression analyses were performed. Six-month progression-free survival (PFS) was 30% and median overall survival (OS) was 7.5 months, in line with literature data. NGS analysis revealed a mutation in the EGFR pathway in 18% of cases and a mutation in the mitogen-activated protein-kinase (MAPK) pathway in 18% of cases. In the remaining cases, no mutations were detected. Patients carrying MAPK pathway mutation had a poor response to regorafenib treatment, with a significantly shorter PFS and a nonsignificantly shorter OS compared to EGFR-mutated patients (for PFS, 2.5 vs 4.5 months, p = 0.0061; for OS, 7 vs 9 months, p = 0.1076). Multivariate analysis confirmed that MAPK pathway mutations independently predicted a shorter PFS after regorafenib treatment (p = 0.0188). The negative prognostic role of MAPK pathway alteration was reinforced when we combined EGFR-mutated with EGFRvIII-positive cases. Recurrent glioblastoma tumors with an alteration in MAPK pathway could belong to the mesenchymal subtype and respond poorly to regorafenib treatment, while EGFR-altered cases have a better response to regorafenib. We thus provide a molecular selection criterion easy to implement in the clinical practice.

[Gastrointestinal stromal tumors (GIST)]

Gastrointestinal stromal tumors (GIST) are rare tumors with a varying malignancy potential, most frequently located in the stomach and the small intestine. The median age at diagnosis is around 65 years. Standard treatment of localized disease is complete surgical resection. A GIST is generally resistant to conventional chemotherapy. Most GISTs harbor tyrosine kinase activating mutations in either the KIT or PDGFRA proto-oncogene. The standard treatment of locally advanced and metastatic GIST with such mutations is the tyrosine kinase inhibitor imatinib. In cases of progressive disease after successive treatment with imatinib, sunitinib, and regorafenib, a fourth-line therapy with ripretinib was recently approved. Approved in 2020, avapritinib is the first effective targeted therapy for advanced stage GIST harboring an imatinib-resistant PDGFRA D842V mutation.

Effect of skeletal muscle loss during neoadjuvant imatinib therapy on clinical outcomes in patients with locally advanced GIST

BACKGROUND

Currently, the effect of skeletal muscle loss during neoadjuvant imatinib therapy on clinical outcomes in patients with locally advanced gastrointestinal stromal tumors (LA-GIST) remains unclear. This study aims to investigate the relationship between changes in skeletal muscle and postoperative complications, survival and tumor response in patients with LA-GIST during neoadjuvant therapy with imatinib.

METHODS

We retrospectively analyzed pre- and post-treatment computed tomography images of 57 GIST patients who underwent radical surgery after neoadjuvant therapy with imatinib from January 2013 to March 2019. Skeletal muscle index (SMI) was measured at the L3 vertebral level in all patients. A cut-off value (SMI < 52.3 cm²/m² and < 38.6 cm²/m² for men and women, respectively) published in a previous study was used to define sarcopenia. Based on gender, we defined ΔSMI (%)/250 days above 9.69% for men and ΔSMI (%)/250 days above 7.63% for women as significant muscle loss (SML). Factors associated with postoperative complications and tumor response were analyzed using logistic regression, and predictors affecting patient prognosis were analyzed using Cox regression.

RESULTS

Of the 57 patients, sarcopenia was present before and after neoadjuvant therapy in 20 (35.09%) and 28 (49.12%) patients, respectively. It was not associated with immediate or long-term clinical outcomes. However, patients with SML during neoadjuvant therapy had a higher incidence of postoperative complications (60.00% vs. 25.00%, p = 0.008), worse pathological regression (44.00% vs. 75.00%, p = 0.017) and worse 3-year survival (Male, 68.75% vs. 95.45%, p = 0.027; Female, 66.67% vs. 100.00%, p = 0.046) than patients without SML.

CONCLUSION

The development of SML during neoadjuvant therapy in LA-GIST patients, rather than pre- and post-treatment sarcopenia, is a major prognostic factor for the long-term prognosis and is also associated with recent postoperative complication rates and pathological regression.

Comparative Assessment of Quantification Methods for Tumor Tissue Phosphoproteomics

With increasing sensitivity and accuracy in mass spectrometry, the tumor phosphoproteome is getting into reach. However, the selection of quantitation techniques best-suited to the biomedical question and diagnostic requirements remains a trial and error decision as no study has directly compared their performance for tumor tissue phosphoproteomics. We compared label-free quantification (LFQ), spike-in-SILAC (stable isotope labeling by amino acids in cell culture), and tandem mass tag (TMT) isobaric tandem mass tags technology for quantitative phosphosite profiling in tumor tissue. Compared to the classic SILAC method, spike-in-SILAC is not limited to cell culture analysis, making it suitable for quantitative analysis of tumor tissue samples. TMT offered the lowest accuracy and the highest precision and robustness toward different phosphosite abundances and matrices. Spike-in-SILAC offered the best compromise between these features but suffered from a low phosphosite coverage. LFQ offered the lowest precision but the highest number of identifications. Both spike-in-SILAC and LFQ presented susceptibility to matrix effects. Match between run (MBR)-based analysis enhanced the phosphosite coverage across technical replicates in LFQ and spike-in-SILAC but further reduced the precision and robustness of quantification. The choice of quantitative methodology is critical for both study design such as sample size in sample groups and quantified phosphosites and comparison of published cancer phosphoproteomes. Using ovarian cancer tissue as an example, our study builds a resource for the design and analysis of quantitative phosphoproteomic studies in cancer research and diagnostics.

New Drug Approvals for Sarcoma in the Last 5 Years

Sarcoma and locally aggressive connective tissue tumors are a complex group of diseases with a growing number of histotypes in the most recent WHO classification. Most of these tumors are rare (incidence <6/10⁵/y) or ultrarare (<1/10⁶/y). Despite their rarity, sarcomas are often good models for the development of personalized medicine, and a large number of new clinical trials in select histotypes and molecular subsets were reported during the past 5 years, leading to a faster rate of new drug approvals. We analyzed the published literature and the abstracts reported in major congresses dedicated to sarcoma and connective tissue tumor management in the last 5 years. Several targeted therapies, cytotoxic treatments, and immunotherapies have demonstrated activity in dedicated histologic and molecular subtypes of sarcomas. The majority of the studies for ultrarare entities are uncontrolled studies, as a consequence of the rarity of histotypes, but randomized controlled trials were available in the less rare histotypes. Most successful trials were based on biomarker selection, which were often driver molecular alterations, while a large number of ongoing research programs aim to identify biomarkers in parallel to new drug development. Availability of the new agents varies across countries. This article describes the new drugs that made it through to the finish line and new agents with promising activity that are in later stages of investigation in the large family of malignant connective tissue tumors.

Neuregulin 1 (NRG1) fusion-positive high-grade spindle cell sarcoma: A distinct group of soft tissue tumors with metastatic potential

Neuregulin 1 (NRG1) is an epidermal growth factor (EGF)-like ligand that activates receptor tyrosine kinases of the ErbB family of receptors. NRG1 gene fusions, which are rare (<1%) but recurrent events in solid tumors, are an emerging oncogenic driver that is potentially actionable using ErbB-targeted tyrosine kinase inhibitors. Largely characterized only in carcinomas, we describe three cases of NRG1-rearranged sarcomas. The patients were all female, aged 32-47 years old. Two cases were deep-seated tumors in the lower extremities (right thigh and calf); one case presented as a uterine mass. The tumors measured 9-11.5 cm in the greatest dimensions. Histologically, all three tumors were high-grade spindle cell sarcomas composed of monomorphic spindle cells arranged in interlacing fascicles. The tumor cells were set in the loose collagenous stroma with branching, curvilinear thin-walled vasculature in the background. Cytologically, the neoplastic cells displayed ovoid to fusiform nuclei with finely stippled chromatin, inconspicuous nucleoli, scant to moderate clear to eosinophilic cytoplasm, occasional cytoplasmic vacuoles, and elongated cytoplasmic processes. Mitotic activity was elevated (> 20/10 high power fields) and tumor necrosis was present. None of the tumors expressed lineage-specific immunophenotypical markers. Targeted RNA-sequencing uncovered gene fusions involving NRG1 and the 5' untranslated regions of PPHLN1, HMBOX1, or MTUS1. In all cases, the C-terminal EGF-like domain of NRG1 was preserved in the predicted chimeric protein product. All three patients developed metastatic disease within 2 years from initial presentation and were alive with disease at last follow-up (mean follow-up period = 19 months). In conclusion, we present the first case series of NRG1-rearranged sarcomas characterized by high-grade fascicular spindle cell morphology, non-specific immunoprofile, and aggressive clinical behavior. Further studies are needed to determine whether this distinct subgroup of spindle cell sarcomas are amenable to targeted therapies.

The Pharmacokinetic Effect of Itraconazole and Voriconazole on Ripretinib in Beagle Dogs by UPLC-MS/MS Technique

BACKGROUND

A new UPLC-MS/MS technique for the determination of ripretinib in beagle dog plasma was developed, and the pharmacokinetic effects of voriconazole and itraconazole on ripretinib in beagle dogs were studied.

METHODS

After extraction with ethyl acetate under alkaline conditions, ripretinib was detected using avapritinib as the internal standard (IS). The mobile phases were 0.1% formic acid-acetonitrile. The scanning method was multi-reaction monitoring using ESI+ source, and the ion pairs for ripretinib and IS were m/z 509.93→416.85 and 499.1→482.09, respectively. This animal experiment adopted a three period self-control experimental design. In the first period, ripretinib was orally administered to six beagle dogs at a dose of 5 mg/kg. In the second period, the same six beagle dogs were orally given itraconazole at a dose of 7 mg/kg, after 30 min, ripretinib was orally given. In the third period, voriconazole at a dose of 7 mg/kg was given orally, and then ripretinib was orally given. At different time points, the blood samples were collected. The concentration of ripretinib was detected, and the pharmacokinetic parameters of ripretinib were calculated.

RESULTS

Ripretinib had a good linear relationship in the range of 1-1000 ng/mL. The precision, accuracy, recovery, matrix effect and stability met the requirements of the guiding principles. After erdafitinib combined with itraconazole, the Cmax and AUC0→t of ripretinib increased by 38.35% and 36.36%, respectively, and the t1/2 was prolonged to 7.53 h. After ripretinib combined with voriconazole, the Cmax and AUC0→t of ripretinib increased by 37.44% and 25.52%, respectively, and the t1/2 was prolonged to 7.33 h.

CONCLUSION

A new and reliable UPLC-MS/MS technique was fully optimized and developed to detect the concentration of ripretinib in beagle dog plasma. Itraconazole and voriconazole could inhibit the metabolism of ripretinib in beagle dogs and increase the plasma exposure of ripretinib.