Efficacy and safety of imatinib mesylate in advanced gastrointestinal stromal tumors

Trends in Diagnosis and Treatment of Metastatic Cancer in the United States

OBJECTIVES

Metastatic cancer has historically been considered fatal; however, there is a paucity of evidence characterizing the epidemiology of incidence, treatment, and outcomes in these patients.

MATERIALS AND METHODS

Incidence rates, annual percent change (APC), descriptive epidemiological statistics, and odds ratios for survival were calculated using registry data from the Surveillance, Epidemiology, and End Results (SEER) and the National Cancer Database (NCDB), 1998 to 2015.

RESULTS

There were a total of 1,055,860 patients with metastatic cancer. The most frequent primary cancers were lung (42.6%), colorectal (9.5%), and ovarian (5.5%). Metastatic lung and colorectal cancer incidence decreased, APC: -1.57 (P<0.001) and APC: -1.48 (P<0.001), respectively; metastatic pancreatic cancer incidence increased, APC: 0.62 (P=0.001). The use of local therapies decreased for almost all sites, and the use of systemic therapies increased across multiple sites: single-agent chemotherapy in kidney (2.54% increase/year), female breast (1.14% increase/year), and prostate cancer (1.08% increase/year); multiagent chemotherapy, most notably in pancreas (2.23% increase/year), uterus (1.81% increase/year), and colorectal cancer (1.54% increase/year). Increased utilization of immunotherapy was observed across the majority of sites, most notably in melanoma (2.14% increase/year). Patients diagnosed from 2006 to 2010 had 17.4% higher odds of surviving at least 60 months compared with 1998 to 2002.

CONCLUSIONS

In this study, metastatic disease has been shown to have unique epidemiological patterns, and survival has improved. Continued research on metastatic disease is important in understanding and addressing the distinct health concerns of this population.

[Surgical and interdisciplinary treatment of gastrointestinal stromal tumors]

Gastrointestinal stromal tumors (GISTs) are the most frequent potentially malignant mesenchymal tumors of the gastrointestinal tract. The treatment of GISTs has been revolutionized since imatinib and other tyrosine kinase inhibitors were introduced for the treatment of GISTs, which inhibit the tyrosine kinases c‑KIT and platelet-derived growth factor receptor (PDGFR) alpha. Even after the introduction of this targeted treatment GISTs can only be cured by surgical resection. With interdisciplinary multimodal treatment the prognosis of metastasized GIST can now be further improved by surgical resection of the primary tumor and the metastases, potentially leading to a cure. Neoadjuvant therapy can reduce the extent of surgical resection and hereby enable organ preservation and reduce surgical morbidity. To evaluate molecular and clinical predictors and to offer an optimal therapeutic plan, patients with GISTs and certainly patients with advanced GISTs should be evaluated by interdisciplinary sarcoma boards.

Small Molecule Kinase Inhibitor Drugs (1995-2021): Medical Indication, Pharmacology, and Synthesis

The central role of dysregulated kinase activity in the etiology of progressive disorders, including cancer, has fostered incremental efforts on drug discovery programs over the past 40 years. As a result, kinase inhibitors are today one of the most important classes of drugs. The FDA approved 73 small molecule kinase inhibitor drugs until September 2021, and additional inhibitors were approved by other regulatory agencies during that time. To complement the published literature on clinical kinase inhibitors, we have prepared a review that recaps this large data set into an accessible format for the medicinal chemistry community. Along with the therapeutic and pharmacological properties of each kinase inhibitor approved across the world until 2020, we provide the synthesis routes originally used during the discovery phase, many of which were only available in patent applications. In the last section, we also provide an update on kinase inhibitor drugs approved in 2021.

Targeted therapy for drug-tolerant persister cells after imatinib treatment for gastrointestinal stromal tumours

BACKGROUND

Despite the effectiveness of tyrosine kinase inhibitors (TKI), gastrointestinal stromal tumours (GIST) develop after the withdrawal of TKI. Based on previous studies, a subpopulation of drug-tolerant cells called "persister cells" may be responsible for the recurrence and have thus, gained attention as a novel target in cancer therapy.

METHODS

The metabolic changes were investigated in imatinib-derived persister GIST cells. We investigated the efficacy and the mechanism of GPX4 inhibitor, which is known as a major inducer of "ferroptosis". We also evaluated the effects of RSL3 to the gefitinib-derived persister lung cancer cells.

RESULTS

We demonstrated a downregulation of glucose metabolism, subsequent decrease in the glutathione level and sensitivity to glutathione peroxidase 4 (GPX4) inhibitor, RSL3 in persister cells. As the cell death induced by RSL3 was found to be "iron-dependent" and "caspase-independent", loss of GPX4 function could have possibly induced selective persister cell ferroptotic death. In the xenograft model, we confirmed the inhibition of tumour regrowth after discontinuation of imatinib treatment. Moreover, RSL3 prevented the growth of gefitinib-derived persister lung cancer cells.

CONCLUSIONS

RSL3 combined with TKI may be a promising therapy for both GIST and epidermal growth factor receptor-mutated lung cancer.

Imatinib augments standard malaria combination therapy without added toxicity

To egress from its erythrocyte host, the malaria parasite, Plasmodium falciparum, must destabilize the erythrocyte membrane by activating an erythrocyte tyrosine kinase. Because imatinib inhibits erythrocyte tyrosine kinases and because imatinib has a good safety profile, we elected to determine whether coadministration of imatinib with standard of care (SOC) might be both well tolerated and therapeutically efficacious in malaria patients. Patients with uncomplicated P. falciparum malaria from a region in Vietnam where one third of patients experience delayed parasite clearance (DPC; continued parasitemia after 3 d of therapy) were treated for 3 d with either the region’s SOC (40 mg dihydroartemisinin + 320 mg piperaquine/d) or imatinib (400 mg/d) + SOC. Imatinib + SOC–treated participants exhibited no increase in number or severity of adverse events, a significantly accelerated decline in parasite density and pyrexia, and no DPC. Surprisingly, these improvements were most pronounced in patients with the highest parasite density, where serious complications and death are most frequent. Imatinib therefore appears to improve SOC therapy, with no obvious drug-related toxicities.

Avapritinib Versus Regorafenib in Locally Advanced Unresectable or Metastatic GI Stromal Tumor: A Randomized, Open-Label Phase III Study

PURPOSE

Primary or secondary mutations in KIT or platelet-derived growth factor receptor alpha (PDGFRA) underlie tyrosine kinase inhibitor resistance in most GI stromal tumors (GISTs). Avapritinib selectively and potently inhibits KIT- and PDGFRA-mutant kinases. In the phase I NAVIGATOR study (NCT02508532), avapritinib showed clinical activity against PDGFRA D842V-mutant and later-line KIT-mutant GIST. VOYAGER (NCT03465722), a phase III study, evaluated efficacy and safety of avapritinib versus regorafenib as third-line or later treatment in patients with unresectable or metastatic GIST.

PATIENTS AND METHODS

VOYAGER randomly assigned patients 1:1 to avapritinib 300 mg once daily (4 weeks continuously) or regorafenib 160 mg once daily (3 weeks on and 1 week off). Primary end point was progression-free survival (PFS) by central radiology per RECIST version 1.1 modified for GIST. Secondary end points included objective response rate, overall survival, safety, disease control rate, and duration of response. Regorafenib to avapritinib crossover was permitted upon centrally confirmed disease progression.

RESULTS

Four hundred seventy-six patients were randomly assigned (avapritinib, n = 240; regorafenib, n = 236). Median PFS was not statistically different between avapritinib and regorafenib (hazard ratio, 1.25; 95% CI, 0.99 to 1.57; 4.2 v 5.6 months; P = .055). Overall survival data were immature at cutoff. Objective response rates were 17.1% and 7.2%, with durations of responses of 7.6 and 9.4 months for avapritinib and regorafenib; disease control rates were 41.7% (95% CI, 35.4 to 48.2) and 46.2% (95% CI, 39.7 to 52.8). Treatment-related adverse events (any grade, grade ≥ 3) were similar for avapritinib (92.5% and 55.2%) and regorafenib (96.2% and 57.7%).

CONCLUSION

Primary end point was not met. There was no significant difference in median PFS between avapritinib and regorafenib in patients with molecularly unselected, late-line GIST.

Pimitespib is effective on cecal GIST in a mouse model of familial GISTs with KIT-Asp820Tyr mutation through KIT signaling inhibition

Three families with multiple gastrointestinal stromal tumors (GISTs) caused by a germline Asp820Tyr mutation at exon 17 of the c-kit gene (KIT-Asp820Tyr) have been reported. We previously generated a knock-in mouse model of the family, and the mice with KIT-Asp818Tyr corresponding to human KIT-Asp820Tyr showed a cecal tumor equivalent to human GIST. In the model mice, we reported that tyrosine kinase inhibitor, imatinib, could stabilize but not decrease the cecal tumor volume. In this report, we examined whether a heat shock protein 90 inhibitor, pimitespib (TAS-116), has an inhibitory effect on phosphorylation of KIT-Asp818Tyr and can decrease the cecal tumor volume in the model mice. First, we showed that pimitespib inhibited KIT phosphorylation both dose- and time-dependently in KIT-Asp818Tyr transfected murine Ba/F3 cells. Then, four 1-week courses of pimitespib were orally administered to heterozygous (KIT-Asp818Tyr/+) model mice. Each course consisted of once-daily administration for consecutive 5 days followed by 2 days-off. Cecal tumors were dissected, and tumor volume was histologically analyzed, Ki-67 labeling index was immunohistochemically examined, and apoptotic figures were counted. Compared to the vehicle treated mice, pimitespib administered mice showed statistically significantly smaller cecal tumor volume, lower Ki-67 labeling index, and higher number of apoptotic figures in 10 high power fields (P = 0.0344, P = 0.0019 and P = 0.0269, respectively). Western blotting revealed that activation of KIT signaling molecules was strongly inhibited in the tumor tissues of pimitespib-administered mice compared to control mice. Thus, pimitespib seemed to inhibit in vivo tumor progression effectively in the model mice. These results suggest that the progression of multiple GISTs in patients with germline KIT-Asp820Tyr might be controllable by pimitespib.

High Prevalence of 5T4/Trophoblast Glycoprotein in Soft Tissue Sarcomas

The expression of 5T4/trophoblast glycoprotein was evaluated in several histological subtypes of soft tissue sarcoma (STS) to determine whether the prevalence and level of expression of this membrane-associated glycoprotein is sufficient for use in targeted therapies. Tumor tissue microarrays containing cores from different histological subtypes of STS were stained using a standardized immunohistochemical staining method to detect 5T4; the level of staining was assessed using a semi-quantitative scoring method. No 5T4 staining was seen in the angiosarcomas and liposarcomas investigated in this study. 5T4 staining in the other STS subtypes was seen in more than 50% of cases, warranting further investigation into whether this antigen could evoke an anti-tumor immune response or can be used as target for the delivery of more potent toxins through antibody drug conjugates.

Comparison of outcomes between neoadjuvant imatinib and upfront surgery in patients with localized rectal GIST: An inverse probability of treatment weighting analysis

BACKGROUND AND OBJECTIVES

This study aimed to compare outcomes between neoadjuvant imatinib and upfront surgery in patients with localized rectal gastrointestinal stromal tumors (GIST) patients.

METHODS

Eighty-five patients with localized rectal GIST were divided into two groups: upfront surgery ± adjuvant imatinib (Group A, n = 33) and the neoadjuvant imatinib + surgery + adjuvant imatinib (Group B, n = 52). Baseline characteristics between groups were controlled for with inverse probability of treatment weighting (IPTW) adjusted analysis.

RESULTS

The response rate to neoadjuvant imatinib was 65.9%. After the IPTW-adjusted analysis, patients who underwent neoadjuvant therapy had better distant recurrence-free survival (DRFS) and disease-specific survival (DSS) compared with those who underwent upfront surgery (5-year DRFS 97.8 vs. 71.9%, hazard ratio [HR], 0.15; 95% CI, 0.03-0.87; p = 0.03; 5-year DSS 100 vs. 77.1%; HR, 0.11; 95% CI, 0.01-0.92; p = 0.04). While no significant association was found between overall survival (OS) and treatment groups (p = 0.07), 5-year OS was higher for the neoadjuvant group than upfront surgery group (97.8% vs. 71.9%; HR, 0.2; 95% CI, 0.03-1.15).

CONCLUSIONS

In patients with localized rectal GIST, neoadjuvant imatinib not only shrunk the tumor size but also decreased the risk of metastasis and tumor-related deaths when compared to upfront surgery and adjuvant imatinib alone.

Association of Combination of Conformation-Specific KIT Inhibitors With Clinical Benefit in Patients With Refractory Gastrointestinal Stromal Tumors: A Phase 1b/2a Nonrandomized Clinical Trial

IMPORTANCE

Many cancer subtypes, including KIT-mutant gastrointestinal stromal tumors (GISTs), are driven by activating mutations in tyrosine kinases and may initially respond to kinase inhibitors but frequently relapse owing to outgrowth of heterogeneous subclones with resistance mutations. KIT inhibitors commonly used to treat GIST (eg, imatinib and sunitinib) are inactive-state (type II) inhibitors.

OBJECTIVE

To assess whether combining a type II KIT inhibitor with a conformation-complementary, active-state (type I) KIT inhibitor is associated with broad mutation coverage and global disease control.

DESIGN, SETTING, AND PARTICIPANTS

A highly selective type I inhibitor of KIT, PLX9486, was tested in a 2-part phase 1b/2a trial. Part 1 (dose escalation) evaluated PLX9486 monotherapy in patients with solid tumors. Part 2e (extension) evaluated PLX9486-sunitinib combination in patients with GIST. Patients were enrolled from March 2015 through February 2019; data analysis was performed from May 2020 through July 2020.

INTERVENTIONS

Participants received 250, 350, 500, and 1000 mg of PLX9486 alone (part 1) or 500 and 1000 mg of PLX9486 together with 25 or 37.5 mg of sunitinib (part 2e) continuously in 28-day dosing cycles until disease progression, treatment discontinuation, or withdrawal.

MAIN OUTCOMES AND MEASURES

Pharmacokinetics, safety, and tumor responses were assessed. Clinical efficacy end points (progression-free survival and clinical benefit rate) were supplemented with longitudinal monitoring of KIT mutations in circulating tumor DNA.

RESULTS

A total of 39 PLX9486-naive patients (median age, 57 years [range, 39-79 years]; 22 men [56.4%]; 35 [89.7%] with refractory GIST) were enrolled in the dose escalation and extension parts. The recommended phase 2 dose of PLX9486 was 1000 mg daily. At this dose, PLX9486 could be safely combined with 25 or 37.5 mg daily of sunitinib continuously. Patients with GIST who received PLX9486 at a dose of 500 mg or less, at the recommended phase 2 dose, and with sunitinib had median (95% CI) progression-free survivals of 1.74 (1.54-1.84), 5.75 (0.99-11.0), and 12.1 (1.34-NA) months and clinical benefit rates (95% CI) of 14% (0%-58%), 50% (21%-79%), and 80% (52%-96%), respectively.

CONCLUSIONS AND RELEVANCE

In this phase 1b/2a nonrandomized clinical trial, type I and type II KIT inhibitors PLX9486 and sunitinib were safely coadministered at the recommended dose of both single agents in patients with refractory GIST. Results suggest that cotargeting 2 complementary conformational states of the same kinase was associated with clinical benefit with an acceptable safety profile.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02401815.

Beyond the Driver Mutation: Immunotherapies in Gastrointestinal Stromal Tumors

Gastrointestinal stromal tumors (GISTs) are a subtype of soft tissue sarcoma (STS), and have become a concept of oncogenic addiction and targeted therapies.The large majority of these tumors develop after a mutation in KIT or platelet derived growth factor receptor α (PDGFRα), resulting in uncontrolled proliferation. GISTs are highly sensitive to imatinib. GISTs are immune infiltrated tumors with a predominance of tumor-associated macrophages (TAMs) and T-cells, including many CD8+ T-cells, whose numbers are prognostic. The genomic expression profile is that of an inhibited Th1 response and the presence of tertiary lymphoid structures and B cell signatures, which are known as predictive to response to ICI. However, the microtumoral environment has immunosuppressive attributes, with immunosuppressive M2 macrophages, overexpression of indoleamine 2,3-dioxygenase (IDO) or PD-L1, and loss of major histocompatibility complex type 1. In addition to inhibiting the KIT oncogene, imatinib appears to act by promoting cytotoxic T-cell activity, interacting with natural killer cells, and inhibiting the expression of PD-L1. Paradoxically, imatinib also appears to induce M2 polarization of macrophages. There have been few immunotherapy trials with anti-CTLA-4 or anti-PD-L1drugs and available clinical data are not very promising. Based on this comprehensive analysis of TME, we believe three immunotherapeutic strategies must be underlined in GIST. First, patients included in clinical trials must be better selected, based on the identified driver mutation (such as PDGFRα D842V mutation), the presence of tertiary lymphoid structures (TLS) or PD-L1 expression. Moreover, innovative immunotherapeutic agents also provide great interest in GIST, and there is a strong rationale for exploring IDO targeting after disease progression during imatinib therapy. Finally and most importantly, there is a strong rationale to combine of c-kit inhibition with immune checkpoint inhibitors.

Therapeutic Implications of Germline Testing in Patients With Advanced Cancers

PURPOSE

Tumor mutational profiling is increasingly performed in patients with advanced cancer. We determined the extent to which germline mutation profiling guides therapy selection in patients with advanced cancer.

METHODS

Patients with cancer undergoing tumor genomic profiling were prospectively consented for germline cancer predisposition gene analysis (2015-2019). In patients harboring germline likely pathogenic or pathogenic (LP/P) alterations, therapeutic actionability was classified using a precision oncology knowledge base. Patients with metastatic or recurrent cancer receiving germline genotype-directed therapy were determined.

RESULTS

Among 11,947 patients across > 50 malignancies, 17% (n = 2,037) harbored a germline LP/P variant. By oncology knowledge base classification, 9% (n = 1042) had an LP/P variant in a gene with therapeutic implications (4% level 1; 4% level 3B; < 1% level 4). BRCA1/2 variants accounted for 42% of therapeutically actionable findings, followed by CHEK2 (13%), ATM (12%), mismatch repair genes (11%), and PALB2 (5%). When limited to the 9,079 patients with metastatic or recurrent cancer, 8% (n = 710) harbored level 1 or 3B genetic findings and 3.2% (n = 289) received germline genotype-directed therapy. Germline genotype-directed therapy was received by 61% and 18% of metastatic cancer patients with level 1 and level 3B findings, respectively, and by 54% of BRCA1/2, 75% of mismatch repair, 43% of PALB2, 35% of RAD51C/D, 24% of BRIP1, and 19% of ATM carriers. Of BRCA1/2 patients receiving a poly(ADP-ribose) polymerase inhibitor, 45% (84 of 188) had tumors other than breast or ovarian cancer, wherein the drug, at time of delivery, was delivered in an investigational setting.

CONCLUSION

In a pan-cancer analysis, 8% of patients with advanced cancer harbored a germline variant with therapeutic actionability with 40% of these patients receiving germline genotype-directed treatment. Germline sequence analysis is additive to tumor sequence analysis for therapy selection and should be considered for all patients with advanced cancer.

Avapritinib in unresectable or metastatic gastrointestinal stromal tumor with PDGFRA exon 18 mutation: safety and efficacy

INTRODUCTION

Avapritinib (formerly known as BLU-285) is an orally available type I tyrosine kinase inhibitor that, in 2020, obtained regulatory approval for the treatment of patients with gastrointestinal stromal tumors (GISTs) harboring a primary mutation in PDGFRA exon 18, including the PDGFRA D842V mutation.

AREAS COVERED

Herein, we comprehensively review the available efficacy and safety data on avapritinib, with the final goal of providing practical knowledge to both sarcoma and community-based oncologists for the correct management of this rare GIST subpopulation with this novel therapy.

EXPERT OPINION

The approval of avapritinib in GIST is a milestone in precision oncology, as this is the first agent ever demonstrating unequivocal antitumoral activity in GIST driven by the multi-resistant PDGFRA D842V mutation. The safety profile is manageable and tolerability-guided dose adjustment is recommended to manage treatment-related adverse events without compromising efficacy. Based on its unprecedented activity, avapritinib should be considered as first-line therapy for GIST patients harboring this mutation. We strongly recommend to determine KIT/PDGFRA genotype in order to identify the different GIST molecular subtypes and guide treatment decision.

A Randomized Phase 2 Study Of Nivolumab Monotherapy Or Nivolumab Combined with Ipilimumab In Patients with Advanced Gastrointestinal Stromal Tumors

PURPOSE

Most GISTs are driven by KIT/PDGFRa mutations. TKI benefit is progressively less after imatinib failure. This phase II trial analyzed the efficacy of nivolumab (N) or nivolumab + ipilimumab (N + I) in refractory GIST patients.

PATIENTS AND METHODS

Advanced/metastatic GIST patients refractory to at least imatinib were randomized 1:1 in a noncomparative, parallel group, unblinded Phase 2 trial of N (240mg Q2wks) or N + I (240 mg Q2wks + 1mg/kg Q6wks). The primary endpoint was the ORR of N alone or N+I by RECIST 1.1 in the ITT population.

RESULTS

36 patients with a median of 3 (1-6) prior lines of therapies were enrolled. 10/19(52.6%) patients had SD for a CBR of 52.6 % in the N arm and the median PFS was 11.7 wks (95% CI, 7.0, 17.4). In the N+I arm, 1/16(6.7%) patients had a CR and 4/16(25.0%) had SD for a CBR of 31.3% and a median PFS of 8.3wks (95% CI, 5.6, 22.2). The 4 and 6 month PFS were 42.1% and 26.3%, respectively for N and 31.3% and 18.8%, respectively for N+I. The most common adverse events (AEs) attributed to N and N+I were fatigue: 13.9% and 22.2%, respectively. There were 9 total attributable grade 3-4 AEs.

CONCLUSIONS

The primary endpoint of RR>15% was not observed for N or N + I. In a heavily pretreated GIST population, responses and long term disease control with both N and N+I were observed. No new safety signals have been observed.

Gastrointestinal stromal tumour lacking mutations in the KIT and PDGFRA genes in a cat

Molecular subtyping in gastrointestinal stromal tumours is a useful method for predicting the efficacy of treatment using tyrosine kinase inhibitors in humans. However, owing to the paucity of reports on mutational analyses, the association between genetic mutations and the therapeutic response to tyrosine kinase inhibitors remains unclear in feline gastrointestinal stromal tumours. In this report, we describe the case of a cat with a gastrointestinal stromal tumour which was unresponsive to tyrosine kinase inhibitors. A mutational analysis revealed that the cat lacked mutations in both the KIT and platelet-derived growth factor receptor-alpha (PDGFRA) genes. Our findings are consistent with the fact that KIT/PDGFRA wild-type gastrointestinal stromal tumours are less responsive to tyrosine kinase inhibitors in humans. This signifies the need for further evaluation and possibly individualised treatment for gastrointestinal stromal tumours in cats on the basis of mutational analyses.

Gastrointestinal stromal tumors with BRAF gene fusions. A report of two cases showing low or absent KIT expression resulting in diagnostic pitfalls

Although most gastrointestinal stromal tumors (GISTs) exhibit activating mutations in either KIT or PDGFRA, rare cases have shown to be driven by gene fusions involving kinases, mainly involving NTRK3, and rarely BRAF or FGFR1. BRAF gene rearrangements have been described in only two patients to date, as separate case reports. In addition, BRAF V600E mutation is an uncommon but established oncogenic pathway in GIST. In this report, we describe two new GIST cases harboring novel BRAF fusion genes, arising in two young-adult women (37 and 40 years of age) in the small bowel and distal esophagus, both with a spindle cell phenotype. The small bowel GIST measured 2.8 cm and showed a high cellularity and a mitotic rate of 20/50 HPFs, while the esophageal lesion measured 7 cm and 1/50 HPFs. Immunohistochemically, both tumors showed diffuse reactivity for DOG1, while KIT/CD117 was weakly positive in the small bowel GIST and completely negative in the esophageal tumor. Based on these findings, the latter case was misinterpreted as a low-grade myxoid leiomyosarcoma, as it showed a myxoid stroma, reactivity for SMA and focal positivity for desmin. Archer FusionPlex revealed a fusion between BRAF with either AGAP3 or MKRN1 gene partners. Moreover, MSK-IMPACT DNA targeted sequencing confirmed both fusions but did not identify additional mutations. In one case with available material, the BRAF gene rearrangement was also validated by FISH. The recognition of BRAF fusion-positive GISTs is critical as it may be associated with a low level of KIT expression and may result in diagnostic challenges with significant impact on therapeutic management. The clinical benefit with KIT inhibitors, such as imatinib, remains to be determined.

C-KIT Expression in Orbital Cavernous Venous Hemangiomas

Orbital (slow flow) cavernous venous hemangiomas (OCVH) are the most common benign orbital tumors in adults. The c-KIT is a tyrosine kinase receptor, which is expressed on several types of cells, is thought to play a key role in tumor pathogenesis. The purpose of this study was to evaluate the presence of the receptor c-KIT in OCVH. Our retrospective study examined 16 orbital cavernous venous hemangiomas from 16 cases operated on between 2006–2016 at Emek Medical Center. The mean tumor size was 18.4 mm. Symptoms appeared between 6 months and 22 years before operation. All specimens were analyzed for the c-KIT receptor through immunohistochemistry. The c-KIT was expressed by the endothelium in all 16 preparates. Staining was strong in two cases, moderate in six, and weak in eight cases, with no statistically significant correlation between staining and tumor size (p = 0.69) or the symptom duration (p = 0.15). We conclude that c-KIT may play an important role in the pathogenesis of OCVH. This pilot study is significant in that tumor-targeted therapy such as Imatinib Mesylate and Sunitinib may have a role in treating surgically complicated cases located in the orbital apex. A large multicenter collaborative study is necessary to examine the role of c-KIT in OCVH.

Gastric Gastrointestinal Stromal Tumor with Repeated Recurrence at the Anastomosis Site in a Very Elderly Patient

Although high-risk gastrointestinal stromal tumors (GISTs) frequently recur, even after a complete resection and imatinib therapy, local recurrence at the suture line after complete resection is rare. The present case was an 88-year-old woman who was initially diagnosed with high-risk GIST without a distant metastasis. She underwent a complete surgical resection of the lesion and received adjuvant imatinib therapy for 18 months, which was discontinued due to severe drug-induced anemia. During the follow- up, an endoscopic examination performed 40 months after the initial surgery revealed local recurrence at the anastomosis site. Although a complete surgical resection was performed, repeated local recurrence was detected 18 months later, which progressed rapidly to metastatic disease. This paper reports a case of a completely resected gastric GIST with repeated local recurrence, despite the complete surgical resections and adjuvant imatinib therapy.

Immune Cell Infiltration and the Expression of PD-1 and PD-L1 in Primary PDGFRA-Mutant Gastrointestinal Stromal Tumors

PURPOSE

To characterize the immune cell profile and expression of PD-1, PD-L1, and IDO in PDGFRA-mutant gastrointestinal stromal tumors (GISTs).

METHODS

The clinicopathological data of PDGFRA-mutant GIST patients who received surgical resection in Zhongshan Hospital between January 2013 and August 2019 were reviewed retrospectively. The specimens of tissue chips were detected for immune cell infiltration and the expression of PD-1, PD-L1, and IDO by immunohistochemical staining.

RESULTS

CD3⁺, CD8⁺, and CD68⁺ cells were the main infiltrating immune cells in the 42 patients included in this study. In addition, CD4⁺, CD56⁺, Foxp3⁺, and CD20⁺ cells were also observed. A higher CD8⁺ T cell count was associated with smaller tumor size and PDGFRA D842V mutation (P = 0.047, P = 0.005). A higher CD3⁺ and CD68⁺ cell count was associated with a higher mitotic index (P = 0.022, P = 0.006). CD4⁺ and CD20⁺ cell count was associated with tumor morphology (P = 0.002, P = 0.045). PD-1 expression was present in 37 (88%) samples. Eighteen samples were positive for PD-L1 expression, and it was higher in small vs. large tumors (P = 0.012) and epithelioid and mixed cell type vs. spindle cell type GISTs (P = 0.046). IDO expression was positive in all 42 patients. The number of CD4⁺ cells was significantly greater in the specimens with high IDO expression (P = 0.012).

CONCLUSION

There were abundant infiltrating immune cells in PDGFRA-mutant GISTs. PD-L1 expression was negatively associated with tumor size. The immunotherapy targeting PD-1/PD-L1 checkpoint and IDO may be valuable.

Inhibition of PI3K and MAPK pathways along with KIT inhibitors as a strategy to overcome drug resistance in gastrointestinal stromal tumors

Activating mutations in KIT/PDGFRA receptor tyrosine kinases drive gastrointestinal stromal tumors (GIST). KIT/PDGFRA inhibitors, such as imatinib do not evoke an effective cytocidal response, leaving room for quiescence and development of multiple secondary resistance mutations. As the majority of the secondary resistance clones activate PI3K and MAPK pathways, we investigated whether combined targeting of KIT/PI3K/MAPK (KPM) pathways overcomes drug resistance and quiescence in GIST cells. We monitored the proliferation of imatinib–sensitive and–resistant GIST cell lines after treating them with various combinations of drugs to inhibit KPM pathways. Cytocidal response was evaluated through proliferation, apoptosis and colony outgrowth assays. Combined inhibition of KPM signaling pathways using a KPM inhibitor cocktail decreased the survival of drug-resistant GIST cells and dramatically reduced their proliferation. Downstream pathway analysis showed that the residual PI3K/MAPK signaling observed after KIT inhibitor treatment plays a role in mediating quiescence and drug resistance. The KPM inhibitor cocktail with sunitinib or regorafenib effectively induced apoptosis and prevented colony outgrowth after long-term drug removal, suggesting that it can be used as an effective strategy against quiescence and drug resistance in metastatic GIST.

Delayed adjuvant imatinib in patients with high risk of recurrence of gastrointestinal stromal tumor after radical surgery: a retrospective cohort study

PURPOSE

To investigate the impact of delayed adjuvant imatinib on GIST patients with high risk of recurrence.

METHOD

Adult GIST patients were retrospectively collected from our hospital between 2011 and 2018, and patients having high risk of recurrence were included for subsequent analyses. The primary endpoint was recurrence-free survival (RFS).

RESULTS

According to the interval between the radical surgery and the beginning of adjuvant imatinib, 222 patients were divided into three groups: group A (≤ 2 months, n = 41), group B (2-≤ 4 months, n = 113), and group C (4-≤ 6 months, n = 68). Univariate, multivariate, and survival analyses all showed that patients in group A had significantly more favorable RFS than those in group C but not group B, and patients taking adjuvant imatinib for over 12 months were also associated with longer RFS comparing to adjuvant imatinib of ≤ 12 months. When stratified by the duration of adjuvant imatinib, no significant differences were found in RFS among groups A, B, and C for adjuvant imatinib of ≤ 12 months. While for adjuvant imatinib of over 12 months, both groups A and B had significantly more favorable RFS than group C, and no significant difference in RFS was found between group A and B.

CONCLUSION

Delayed postoperative adjuvant imatinib for over 4 months in patients with high risk of recurrence of GIST may lead to worse RFS, and longer treatment with shorter delay has best results.

Combined Inhibition of AKT and KIT Restores Expression of Programmed Cell Death 4 (PDCD4) in Gastrointestinal Stromal Tumor

The majority of gastrointestinal stromal tumor (GIST) patients develop resistance to the first-line KIT inhibitor, imatinib mesylate (IM), through acquisition of secondary mutations in KIT or bypass signaling pathway activation. In addition to KIT, AKT is a relevant target for inhibition, since the PI3K/AKT pathway is crucial for IM-resistant GIST survival. We evaluated the activity of a novel pan-AKT inhibitor, MK-4440 (formerly ARQ 751), as monotherapy and in combination with IM in GIST cell lines and preclinical models with varying IM sensitivities. Dual inhibition of KIT and AKT demonstrated synergistic effects in IM-sensitive and -resistant GIST cell lines. Proteomic analyses revealed upregulation of the tumor suppressor, PDCD4, in combination treated cells. Enhanced PDCD4 expression correlated to increased cell death. In vivo studies revealed superior efficacy of MK-4440/IM combination in an IM-sensitive preclinical model of GIST compared with either single agent. The combination demonstrated limited efficacy in two IM-resistant models, including a GIST patient-derived xenograft model possessing an exon 9 KIT mutation. These studies provide strong rationale for further use of AKT inhibition in combination with IM in primary GIST; however, alternative agents will need to be tested in combination with AKT inhibition in the resistant setting.

Gastrointestinal Stromal Tumor (GIST) from esophagus to anorectum - diagnosis, response evaluation and surveillance on computed tomography (CT) scan

Gastrointestinal stromal tumor (GIST) are the most common non epithelial tumor of the gastrointestinal (GI) tract. They arise from interstitial cells of Cajal present in the myenteric plexus. They can also arise outside the GI tract from mesentery, retro peritoneum and omentum. With the advent of new targeted molecular therapy c- tyrosine kinase inhibitor (Imatinib), it has become important to differentiate between response and pseudo-progression of the disease as response evaluation criteria for GIST are different from Response Evaluation Criteria in Solid Tumors (RECIST). Purpose of this pictorial essay is to enumerate the characteristic CT features of GIST, and discuss atypical features and response evaluation criteria.

Preseptal cellulitis, intraocular inflammatory reaction and corneal persistent epithelial defect as side effects of avapritinib

Avapritinib is a tyrosine kinase inhibitor currently being investigated on clinical trials for the treatment of unresectable or metastatic gastrointestinal stromal tumour (GIST). It has been recently approved by the Food and Drug Administration and the European Medicines Agency for the treatment of unresectable or metastatic GIST harbouring PDGFRa Exon 18 mutation and by the European Medicines Agency for the treatments of unresectable or metastatic GIST harbouring the PDGFRa D842V mutation. We report a clinical case of a 76-year-old female, diagnosed with a stage IV GIST, treated with avapritinib 300 mg once daily. through compassionate use who experienced an intraocular side effect not previously reported avapritinib. She developed preseptal cellulitis on her right eye following 2 months of treatment with avapritinib and, subsequently evolved to an intraocular inflammatory reaction and persistent corneal epithelial defect. The treatment with avapritinib was stopped and the patient received corticosteroid and corneal regenerating agents. The symptoms resolved within 1 month and the patient has remained on stable disease at two subsequent adjusted avapritinib doses (100 mg once daily) for over 1 year.

Benefit of pazopanib in advanced gastrointestinal stromal tumours: results from a phase II trial (SSG XXI, PAGIST)

BACKGROUND

Patients with advanced gastrointestinal stromal tumours (GISTs) resistant to the tyrosine kinase inhibitors imatinib and sunitinib may be treated with regorafenib, which resulted in a median progression-free survival (PFS) of 4.8 months in the GRID trial. Also, pazopanib, another tyrosine kinase inhibitor, has been studied in a randomized, placebo-controlled trial (PAZOGIST) in the third line, which showed a PFS of 45.2% 4 months after study entry, but patients intolerant to sunitinib were also included. We designed another trial evaluating pazopanib, enrolling only patients with progression on both imatinib and sunitinib.

PATIENTS AND METHODS

Since all eligible patients had progressive disease, we preferred a non-randomized, phase II multicentre trial so that all patients could receive a potentially active drug. Patients had a progressive metastatic or locally advanced GIST and were ≥18 years of age, with a performance status of 0-2, and sufficient organ functions. The primary endpoint was disease control rate (defined as complete remission + partial remission + stable disease) at 12 weeks on pazopanib. A Simon's two-stage analysis was used with an interim analysis 12 weeks after enrollment of the first 22 patients, and if passed, there was a full enrolment of 72 patients. GIST mutational analysis was done, and most patients had pazopanib plasma concentration measured after 12 weeks.

RESULTS

Seventy-two patients were enrolled. The disease control rate after 12 weeks was 44%, and the median PFS was 19.6 weeks (95% confidence interval 12.6-23.4 weeks). Pazopanib-related toxicity was moderate and manageable. No statistically significant differences were found related to mutations. Plasma concentrations of pazopanib had a formal but weak correlation with outcome.

CONCLUSION

Pazopanib given in the third line to patients with GIST progressing on both imatinib and sunitinib was beneficial for about half of the patients. The PAGIST trial confirms the results from the PAZOGIST trial, and the median PFS achieved seems comparable to the PFS achieved with regorafenib in the third-line setting.

Molecular Mechanism and Prevention Strategy of Chemotherapy- and Radiotherapy-Induced Ovarian Damage

Fertility preservation is an emerging discipline, which is of substantial clinical value in the care of young patients with cancer. Chemotherapy and radiation may induce ovarian damage in prepubertal girls and young women. Although many studies have explored the mechanisms implicated in ovarian toxicity during cancer treatment, its molecular pathophysiology is not fully understood. Chemotherapy may accelerate follicular apoptosis and follicle reservoir utilization and damage the ovarian stroma via multiple molecular reactions. Oxidative stress and the radiosensitivity of oocytes are the main causes of gonadal damage after radiation treatment. Fertility preservation options can be differentiated by patient age, desire for conception, treatment regimen, socioeconomic status, and treatment duration. This review will help highlight the importance of multidisciplinary oncofertility strategies for providing high-quality care to young female cancer patients.

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

The majority of gastrointestinal stromal tumors (GIST) harbor an activating mutation in either the KIT or PDGFRA receptor tyrosine kinases. Approval of imatinib, a KIT/PDGFRA tyrosine kinase inhibitor (TKI), meaningfully improved the treatment of advanced GIST. Other TKIs subsequently gained approval: sunitinib as a second-line therapy and regorafenib as a third-line therapy. However, resistance to each agent occurs in almost all patients over time, typically due to secondary kinase mutations. A major limitation of these 3 approved therapies is that they target the inactive conformation of KIT/PDGFRA; thus, their efficacy is blunted against secondary mutations in the kinase activation loop. Neither sunitinib nor regorafenib inhibit the full spectrum of KIT resistance mutations, and resistance is further complicated by extensive clonal heterogeneity, even within single patients. To combat these limitations, next-generation TKIs were developed and clinically tested, leading to 2 new USA FDA drug approvals in 2020. Ripretinib, a broad-spectrum KIT/PDGFRA inhibitor, was recently approved for the treatment of adult patients with advanced GIST who have received prior treatment with 3 or more kinase inhibitors, including imatinib. Avapritinib, a type I kinase inhibitor that targets active conformation, was approved for the treatment of adults with unresectable or metastatic GIST harboring a PDGFRA exon 18 mutation, including PDGFRA D842V mutations. In this review, we will discuss how resistance mutations have driven the need for newer treatment options for GIST and compare the original GIST TKIs with the next-generation KIT/PDGFRA kinase inhibitors, ripretinib and avapritinib, with a focus on their mechanisms of action.

Succinate dehydrogenase-deficient gastrointestinal stromal tumor: from diagnostic dilemma to novel personalised therapy in 2 case reports

Succinate dehydrogenase (SDH)-deficient gastrointestinal stromal tumor (GIST) is a unique and distinctive subtype of gastric GIST. The literature on this subtype from developing countries is exceedingly sparse. Patients with SDH-deficient GIST often experience a lack or delay in genomic profiling, despite stereotypical clinicopathologic features, potentially resulting in sub-optimal management. SDH-deficient GISTs are highly syndromic, typically have more indolent behavior, a prognosis not predicted by size and mitotic rate, a tendency to lymph node metastases, and are insensitive to standard tyrosine kinase inhibitors (TKIs). We report two women with SDH-deficient GIST. In the first case, SDH deficiency was identified late due to lack of awareness and poor access to diagnostic facilities. The patient progressed through TKI therapy, but responded to temozolomide, which is under investigation in clinical trials. In the second case, SDH deficiency was identified at diagnosis, and the patient responded well to ¹⁷⁷Lutetium peptide radionuclide receptor therapy (PRRT) after progressing through two lines of TKIs. We aim to highlight the need for more awareness and access to genomic diagnostic facilities for GIST patients, temozolomide as a novel therapy for SDH-deficient GIST, and the potential value of DOTATATE positron emission tomography (PET) and PRRT as a novel imaging modality and therapy for TKI insensitive GIST patients.

Molecular mechanisms underpinning sarcomas and implications for current and future therapy

Sarcomas are complex mesenchymal neoplasms with a poor prognosis. Their clinical management is highly challenging due to their heterogeneity and insensitivity to current treatments. Although there have been advances in understanding specific genomic alterations and genetic mutations driving sarcomagenesis, the underlying molecular mechanisms, which are likely to be unique for each sarcoma subtype, are not fully understood. This is in part due to a lack of consensus on the cells of origin, but there is now mounting evidence that they originate from mesenchymal stromal/stem cells (MSCs). To identify novel treatment strategies for sarcomas, research in recent years has adopted a mechanism-based search for molecular markers for targeted therapy which has included recapitulating sarcomagenesis using in vitro and in vivo MSC models. This review provides a comprehensive up to date overview of the molecular mechanisms that underpin sarcomagenesis, the contribution of MSCs to modelling sarcomagenesis in vivo, as well as novel topics such as the role of epithelial-to-mesenchymal-transition (EMT)/mesenchymal-to-epithelial-transition (MET) plasticity, exosomes, and microRNAs in sarcomagenesis. It also reviews current therapeutic options including ongoing pre-clinical and clinical studies for targeted sarcoma therapy and discusses new therapeutic avenues such as targeting recently identified molecular pathways and key transcription factors.

Discovery and pharmacological characterization of AZD3229, a potent KIT/PDGFRα inhibitor for treatment of gastrointestinal stromal tumors

Gastrointestinal stromal tumor (GIST) is the most common human sarcoma driven by mutations in KIT or platelet-derived growth factor α (PDGFRα). Although first-line treatment, imatinib, has revolutionized GIST treatment, drug resistance due to acquisition of secondary KIT/PDGFRα mutations develops in a majority of patients. Second- and third-line treatments, sunitinib and regorafenib, lack activity against a plethora of mutations in KIT/PDGFRα in GIST, with median time to disease progression of 4 to 6 months and inhibition of vascular endothelial growth factor receptor 2 (VEGFR2) causing high-grade hypertension. Patients with GIST have an unmet need for a well-tolerated drug that robustly inhibits a range of KIT/PDGFRα mutations. Here, we report the discovery and pharmacological characterization of AZD3229, a potent and selective small-molecule inhibitor of KIT and PDGFRα designed to inhibit a broad range of primary and imatinib-resistant secondary mutations seen in GIST. In engineered and GIST-derived cell lines, AZD3229 is 15 to 60 times more potent than imatinib in inhibiting KIT primary mutations and has low nanomolar activity against a wide spectrum of secondary mutations. AZD3229 causes durable inhibition of KIT signaling in patient-derived xenograft (PDX) models of GIST, leading to tumor regressions at doses that showed no changes in arterial blood pressure (BP) in rat telemetry studies. AZD3229 has a superior potency and selectivity profile to standard of care (SoC) agents-imatinib, sunitinib, and regorafenib, as well as investigational agents, avapritinib (BLU-285) and ripretinib (DCC-2618). AZD3229 has the potential to be a best-in-class inhibitor for clinically relevant KIT/PDGFRα mutations in GIST.

Clinicopathological Features and Outcomes of Gastrointestinal Stromal Tumours in Oman: A multi-centre study

Objectives

This study aimed to report the clinicopathological features, management and long-term outcomes of patients with gastrointestinal stromal tumours (GISTs) in Oman.

Methods

This retrospective study was conducted on patients treated for GIST between January 2003 and December 2017 at three tertiary referral centres in Muscat, Oman. All patients with confirmed histopathological diagnoses of GIST and followed-up at the centres during this period were included. Relevant information was retrieved from hospital records until April 2019.

Results

A total of 44 patients were included in the study. The median age was 55.5 years and 56.8% were female. The most common primary site of disease was the stomach (63.6%) followed by the jejunum/ileum (18.2%). Two patients (4.5%) had c-Kit-negative, discovered on GIST-1-positive disease. A total of 24 patients (54.5%) presented with localised disease and eight (33.3%) were classified as being at high risk of relapse. Patients with metastatic disease received imatinib in a palliative setting, whereas those with completely resected disease in the intermediate and high-risk groups were treated with adjuvant imatinib. Of the six patients (13.6%) with progressive metastatic disease, of which four had mutations on exon 11 and one on exon 9, while one had wild-type disease. Overall, rates of progression-free survival and overall survival (OS) at 100 months were 77.4% and 80.4%, respectively. Rates of OS for patients with localised and metastatic disease were 89.9% and 80.2%, respectively.

Conclusion

The presenting features and outcomes of patients with GISTs in Oman were comparable to those reported in the regional and international literature.

The incidence, treatment and survival of patients with rare types of rectal malignancies in the Netherlands: A population-based study between 1989 and 2018

AIM

To describe the incidence, treatment and survival of patients with rare types of rectal malignancies in the Netherlands.

METHODS

Data of patients with rectal malignancies diagnosed in the Netherlands between 1989 and 2018 were retrieved from the Netherlands Cancer Registry and grouped according to the RARECARE cancer list. Age-standardised incidence rates were calculated using the European Standard Rate. The Joinpoint Regression Program was used for analysing trends and joinpoints and for the estimation of annual percentage changes (APCs). Patient characteristics, treatment details and relative survival (RS) were reported for different histological types of rectal malignancies and compared between different time periods. RS was assessed using Kaplan-Meier analysis and log-rank test.

RESULTS

A total of 88,299 cases of rectal malignancies were included of which 2125 (2.5%) were categorised as rare histological subtypes. The incidence of rectal neuro-endocrine tumours (NET) (APC: 6.2%, 95% confidence interval [CI]: 5.4%; 7.1%), rectal sarcoma (APC: 5.8%, 95% CI: 2.9%; 8.7%) and rectal adenocarcinoma (APC 1.0%, 95% CI: 0.26%; 1.8%) increased. Prognosis was best in patients with rectal NET (5-year RS: 72.4%, 95% CI: 70.1%; 74.7%) and worst in patients with rectal melanoma (5-year RS: 8.9%, 95% CI: 5.1%; 15.7%). RS has improved in patients with rectal adenocarcinoma, rectal sarcoma and rectal lymphoma in 2008-2018 (p-values p < 0.001, p = 0.023 and p = 0.029).

CONCLUSION

Significant increases in incidence were observed for different types of rectal malignancies. Differences in incidence, treatment and survival found in this study could be useful to make clinicians aware of specific diseases.

Characteristics of 18F-FDG and 18F-FDOPA PET in an 8-year-old neutered male Yorkshire Terrier dog with glioma: long-term chemotherapy using hydroxyurea plus imatinib with prednisolone and immunoreactivity for PDGFR-β and LAT1

An 8-year-old neutered male Yorkshire Terrier dog presented with head pressing, vestibular ataxia, neck tenderness, and no oculocephalic reflex. A demarcated lesion in the pons was identified on MRI. The patient was tentatively diagnosed with a glioma and was treated with hydroxyurea plus imatinib and prednisolone. After 30 days of therapeutic treatment, the patient showed a clear improvement in neurological signs, which lasted for 1117 days. On day 569 after the initiation of treatment, ¹⁸F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) was performed with no significant findings on visual analysis. The average and maximal standardized uptake values (SUVs) were 1.92 and 2.29, respectively. The tumor-to-normal-tissue (T/N) ratio was 0.97. The first evidence of clinical deterioration was noticed on day 1147. On day 1155, 3,4-dihydroxy-6-[¹⁸F]-fluoro-l-phenylalanine (¹⁸F-FDOPA)-PET was performed. High uptake of ¹⁸F-FDOPA was observed in the intracranial lesion. The mean and maximal SUVs of the tumor were 1.59 and 2.29, respectively. The T/N ratio was 2.22. The patient was euthanized on day 1155 and histopathologic evaluations confirmed glioma (astrocytoma). This case shows that chemotherapy with hydroxyurea plus imatinib may be considered in the treatment of canine glioma. Furthermore, this is the first case describing the application of ¹⁸F-FDG and ¹⁸F-FDOPA in a dog with glioma.

Starting Imatinib at 400 mg Daily in Patients with Gastrointestinal Stromal Tumors Harboring KIT Exon 9 Mutations: A Retrospective, Multicenter Study

BACKGROUND

Retrospective analyses suggest that patients with advanced KIT exon 9-mutated gastrointestinal stromal tumors (GISTs) receiving imatinib 800 mg (rather than 400 mg) daily have better outcomes. In the adjuvant setting, the question of the optimal dose of imatinib remains unsettled.

OBJECTIVE

We aimed to retrospectively assess the activity of imatinib 400 mg in both the adjuvant and the advanced settings.

PATIENTS AND METHODS

We performed a multicenter study of patients with KIT exon 9-mutated GIST starting imatinib at 400 mg daily. We examined the relapse-free survival (RFS) among high-risk patients either receiving or not receiving adjuvant imatinib. In patients with advanced disease, progression-free survival (PFS, progression under imatinib 400 mg), time to imatinib failure (TIF, progression under imatinib 400, then 800 mg upon first progression), and overall survival (OS) were analyzed.

RESULTS

In the post-operative setting (n = 37), 20 patients received adjuvant imatinib. Median RFS in high-risk patients receiving adjuvant imatinib (n = 14) was not reached (95% CI 17.5-46.6) versus 13.6 months (95% CI 4.7-13.6) for those who did not (p = 0.37), after a median follow-up of 58 months. RFS at 36 months was 63% (30.3-96.6) versus 40% (95% CI 0-82.9), p = 0.2. In advanced disease (n = 28), median PFS, TIF and OS were 12.7 months (95% CI 6.1-18.2), 21.0 months (95% CI 17.4-28.1) and 47.0 months (95% CI 33.5-69.2), respectively.

CONCLUSIONS

Despite the limitations of a retrospective analysis and the small number of patients, the benefit of adjuvant imatinib 400 mg daily in high-risk patients appeared relevant. Patients with advanced disease receiving imatinib 400 mg with subsequent dose escalation had a TIF similar to that observed with an initial dose of 800 mg. Intra-patient dose escalation in this setting might be an option.

Refractory hypoglycaemia in a localised gastrointestinal stromal tumour: Case report

Introduction

GIST and NICTH are mesenchymal in origin however there are very few reports of GIST associated with NICTH which is a para neoplastic syndrome, generally diagnosed when a tumour induced hypoglycaemia is noted.

Case presentation

A 46 years old female with prime complain of awareness of a mass in the upper abdomen was admitted for evaluation and further management. Detailed investigation revealed the mass to be gastrointestinal stromal tumour. On the day of admission patient was found to be hypoglycaemic which didn't resolve even after 10% glucose infusion. A growth hormone releasing peptide-2 (GHRP-2) assay was carried out which showed an excessive reaction of basal growth hormone however corticotropin releasing hormone (CRH) tests were within normal limits. She was suspected to be Non Islet cell tumour hypoglycaemia (NICTH) and hypoglycaemia resolved upon administering dexamethasone. Later she underwent chemotherapy and surgical resection after which her blood sugar levels were within normal limits.

Discussion

Expression of big IGF-II on the surface of GIST be it metastatic or nonmetastatic can cause refractory hypoglycaemia and can be fatal if left untreated.

Conclusion

Clinicians should be aware of refractory hypoglycaemia in patients with large GIST's as glucocorticoid therapy may prove to be extremely useful and lifesaving even before considering any forms of definitive management of the tumour.

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Localised GISTS may present with refractory hypoglycaemia.

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If not diagnosed due to clinical vague nature, it can be fatal.

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It responds very well to steroid treatment and can prevent a potentially fatal condition.

Staged surgical approach for metastatic GIST, how far should we go? Case report

Introduction

Gastrointestinal stromal tumor (GIST) is an uncommon mesenchymal neoplasm that commonly arises from the stomach and proximal small intestine but can develop in any part of the gastrointestinal tract. The disease can range from primary localized to an advanced metastatic unresectable disease in up to 30% of patients. Usually, metastasis involves the liver, peritoneum, and occasionally the lungs. The current standard treatment of localized resectable tumors is complete oncological resection, while advanced metastatic GISTs treatment remains contentious.

Case presentation

We report a case of a 34 years old pregnant female presenting with a 3 days history of multiple episodes of hematemesis and melena. Laboratory investigations were unremarkable except for severe anemia (Hgb 4.4 g/dL). After further investigations a diagnosis of duodenal GIST (DGIST) with liver metastasis was made. She received and showed good response to neoadjuvant Imatinib therapy, which was followed by a successful 2-stage surgery in the form of extended right hepatectomy and Whipple procedure with a good survival.

Clinical dissection

The evolution of Imatinib had a tremendous impact on surgery in metastatic GIST even in initially unresectable cases, thereby providing a better survival. However, the duration of neoadjuvant Imatinib course and the matter of resistance are still unclear those necessitating the use of different agents or the surgical approach.

Conclusion

Although with the advancements in surgical approaches and perioperative care, liver resection might be a curative option. The role of surgery in advanced GIST remains a controversial matter that needs critical selection of cases based on further future research.

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GIST is considered a relatively rare entity, accounting for only 1% of all primary gastrointestinal tumors with the incidence being 10-13 per million population per year.

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We present a case of a 34 pregnant female presenting with vomiting blood and passing melena, which after further examination and investigation was revealed to be due to a duodenal GIST.

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The evolution of Imatinib had a tremendous impact on surgery in metastatic GIST even in initially unresectable cases.

A Nomogram Predicting Progression Free Survival in Patients with Gastrointestinal Stromal Tumor Receiving Sunitinib: Incorporating Pre-Treatment and Post-Treatment Parameters

Simple Summary

Sunitinib has been approved as the second-line targeted treatment for gastrointestinal stromal tumor (GIST) after imatinib failure. It is thus necessary to effectively assess prognosis after sunitinib use. However, the current assessment remains insufficient for the contemporary period. We examined prognostic factors influencing progression-free survival. Furthermore, we constructed a prognostic nomogram model using these significant pre-treatment and post-treatment variables.

Abstract

The present study aimed to construct a prognostic nomogram incorporating pre-treatment and post-treatment factors to predict progression-free survival (PFS) after use of sunitinib in patients with metastatic gastrointestinal stromal tumors (GISTs) following imatinib intolerance or failure. From 2007 to 2018, 109 metastatic GIST patients receiving sunitinib at Chang Gung Memorial Hospital, Taiwan, were enrolled. A prognostic nomogram to predict PFS was developed. Sixty-three male and forty-six female metastatic GIST patients, with a median age of 61 years (range: 15–91 years), received sunitinib. The median PFS for 109 patients is 9.93 months. For pre-treatment factors, male gender, body mass index more than 18.5 kg/m², no sarcopenia status, higher lymphocyte count, lower platelet/lymphocyte ratio, good performance status, higher sunitinib dose, and non-liver metastasis were significantly associated with favorable PFS. For post-treatment factors, adverse events with hypertension, hand–foot skin reaction, and diarrhea were significantly associated with favorable PFS. However, only eight clinicopathological independent factors for PFS prediction were selected for prognostic nomogram establishment. The calibration curve for probability of PFS revealed good agreement between the nomogram prediction and actual observation. High risk patients will experience the lowest PFS. A prognostic nomogram integrating eight clinicopathological factors was constructed to assist prognostic prediction for individual patients with advanced GIST after sunitinib use.

Quantitative proteomic analysis of aberrant expressed lysine acetylation in gastrointestinal stromal tumors

BACKGROUND

Gastrointestinal stromal tumor (GIST) is a common digestive tract tumor with high rate of metastasis and recurrence. Currently, we understand the genome, transcriptome and proteome in GIST. However, posttranscriptional modification features in GIST remain unclear. In the present study, we aimed to construct a complete profile of acetylome in GIST.

METHODS

Five common protein modifications, including acetylation, succinylation, crotonylation, 2-hydroxyisobutyrylation, and malonylation were tested among GIST subgroups and significantly differentially- expressed lysine acetylation was found. The acetylated peptides labeled with Tandem Mass Tag (TMT)under high sensitive mass spectrometry, and some proteins with acetylation sites were identified. Subsequently, these proteins and peptides were classified into high/moderate (H/M) risk and low (L) risk groups according to the modified NIH classification standard. Furthermore, cell components, molecular function, biological processes, KEGG pathways and protein interaction networks were analyzed.

RESULTS

A total of 2904 acetylation sites from 1319 proteins were identified, of which quantitative information of 2548 sites from 1169 proteins was obtained. Finally, the differentially-expressed lysine acetylation sites were assessed and we found that 42 acetylated sites of 38 proteins were upregulated in the H/M risk group compared with the L risk group, while 48 acetylated sites of 44 proteins were downregulated, of which Ki67 K1063Ac and FCHSD2 K24Ac were the two acetylated proteins that were most changed.

CONCLUSIONS

Our novel findings provide further understanding of acetylome in GIST and might demonstrate the possibility in the acetylation targeted diagnosis and therapy of GIST.

An updated review of the treatment landscape for advanced gastrointestinal stromal tumors

Before the introduction of tyrosine kinase inhibitors (TKIs), the overall survival of patients with advanced or metastatic gastrointestinal stromal tumors (GISTs) was 10 to 20 months because of the lack of approved therapies. In the last 20 years, a treatment algorithm for patients with advanced GISTs, which includes imatinib, sunitinib, and regorafenib as first‐, second‐, and third‐line therapies, respectively, has been established. Recently, 2 new TKIs have been approved: ripretinib for fourth‐line therapy and avapritinib as first‐line therapy in patients harboring platelet‐derived growth factor receptor α (PDGFRA) exon 18 D842V mutations. Additionally, there are several experimental therapies under investigation that could advance individualized patient care. All of these therapies have varying efficacies and safety profiles that warrant an updated treatment landscape review. This review article summarizes the efficacy and safety data currently available for conventional TKIs along with recently approved and experimental therapies.

With evolving treatment options and effective toxicity management, patients with advanced gastrointestinal stromal tumors are living longer than ever before. Recently approved targeted therapies and the investigation of experimental treatment options have the potential to alter the current treatment algorithm and encourage personalized patient care.

[New data on the molecular biology of soft tissue sarcoma]

Sarcoma consists in a group of rare malignant tumours of mesenchymal origin characterized by their vast clinical, pathological and biological heterogeneity. The pathological diagnosis of sarcoma relies classically of the differentiation features of tumour cells, with dozens of different tumour subtypes described in the last international classifications. Over the last decades, the advances in the development of new techniques of molecular biology have led to a major complexification of sarcoma classification, with the identification of multiple and specific molecular alterations that have led to significant changes for patients diagnostic, prognostic and therapeutic management. This review aims at giving an overview on the current knowledge of the molecular biology of soft tissue sarcoma, and emphasizes on their consequences for the daily management of patients.

Infections associated with the new 'nibs and mabs' and cellular therapies

PURPOSE OF REVIEW

In recent years, we have witnessed a remarkable surge in the clinical development of effective biological and cellular therapies for the treatment of neoplastic and autoimmune disorders. The present review summarizes our understanding of the pathogen-specific infection risk associated with the use of such therapies.

RECENT FINDINGS

A variety of biologics, in the form of either monoclonal antibodies (Mabs) or small molecule kinase inhibitors (Nibs), are continuously introduced in the clinic for the management of autoimmune and malignant diseases. In addition, cellular therapies such as the infusion of chimeric antigen receptor (CAR) T-cells are becoming increasingly available for patients with treatment-refractory lymphoid malignancies. Some of these biological and cellular interventions exert direct or indirect adverse effects on the induction of protective immune responses against various pathogens, resulting in heightened infection susceptibility.

SUMMARY

The introduction of biological and cellular therapies for the treatment of malignant and autoimmune diseases has been associated with increased infection susceptiblity, which varies greatly depending on the specific immunomodulatory therapy, the infecting pathogen and the recipient patient population. A high index of clinical suspicion and efforts aiming at early diagnosis, targeted vaccination or prophylaxis, and prompt initiation of antimicrobial treatment should help improve infection outcomes.

Indocyanine green-labeled dasatinib as a new fluorescent probe for molecular imaging of gastrointestinal stromal tumors

BACKGROUND AND AIM

It is difficult to differentiate gastrointestinal stromal tumors (GISTs) from other subepithelial lesions under gastrointestinal endoscopy. Because most GISTs express tyrosine kinase receptor c-KIT, fluorescence-labeled c-KIT-specific tyrosine kinase inhibitors seem to be useful agents for molecular imaging of GIST. We aimed to develop a near-infrared fluorescent imaging technology for GIST targeting c-KIT using the novel fluorescent probe indocyanine green-labeled dasatinib (ICG-dasatinib) and to investigate the antitumor effect of ICG-dasatinib on GIST cells.

METHODS

Indocyanine green-labeled dasatinib was synthesized by labeling linker-induced dasatinib with ICG derivative 3-indocyanine-green-acyl-1,3-thiazolidine-2-thione. Human GIST cell lines GIST-T1 and GIST-882M were incubated with ICG-dasatinib and observed by fluorescent microscopy. GIST cells were incubated with ICG-dasatinib, unlabeled dasatinib, or imatinib, and cell viabilities were evaluated. Subcutaneous GIST model mice or orthotopic GIST model rats were intravenously injected with ICG-dasatinib and observed using an IVIS Spectrum.

RESULTS

Strong fluorescent signals of ICG-dasatinib were observed in both GIST cell lines in vitro. IC50 values for ICG-dasatinib, unlabeled dasatinib, and imatinib were 13.9, 1.17, and 16.2 nM in GIST-T1 and 26.6, 3.63, and 47.6 nM in GIST-882M cells, respectively. ICG-dasatinib accumulated in subcutaneous xenografts in mice. Fluorescent signals were also observed in liver and gallbladder, indicating biliary excretion; however, fluorescence intensity of tumors was significantly higher than that of intestine after washing. Strong fluorescent signals were observed in orthotopic xenografts through the covering normal mucosa in rats.

CONCLUSIONS

Indocyanine green-labeled dasatinib could visualize GIST cells and xenografted tumors. The antitumor effect of ICG-dasatinib was preserved to the same degree as imatinib.

ABCG2 Single Nucleotide Polymorphism Affects Imatinib Pharmacokinetics in Lower Alpha-1-Acid Glycoprotein Levels in Humans

Imatinib is transported extracellularly by ABCB1 and ABCG2 efflux transporters and bound to alpha-1-acid glycoprotein (AGP) in the bloodstream. However, the clinical and pharmacokinetic effects of ABCB1 and ABCG2 on imatinib were inconsistent in the previous literature and have not been confirmed. Therefore, in the present study, we explored the effects of the ABCG2 and ABCB1 genetic polymorphisms on imatinib pharmacokinetics in association with plasma AGP levels in healthy subjects. Twenty-seven healthy individuals were recruited, genotyped for ABCG2 and ABCB1, and given a single oral dose of 400 mg imatinib. Plasma imatinib concentrations were measured and its pharmacokinetics was assessed with respect to ABCG2 (c.421C>A and c.34G>A) and ABCB1 (c.1236C>T, c.2677C>T/A, and c.3435C>T) genotypes, and plasma AGP levels. AGP levels showed a strong positive correlation with imatinib pharmacokinetics. ABCG2 c.421C>A single nucleotide polymorphism showed a statistically significant effect on imatinib pharmacokinetics in low plasma AGP levels groups (<80 mg/dl); subjects with high plasma AGP levels (n = 5, ≥80 mg/dl) were excluded. The results indicate that plasma AGP levels and ABCG2 polymorphisms modulated imatinib pharmacokinetics; however, the effects of the ABCG2 transporter was masked at high plasma AGP levels.

Digital Display Precision Predictor: the prototype of a global biomarker model to guide treatments with targeted therapy and predict progression-free survival

The expanding targeted therapy landscape requires combinatorial biomarkers for patient stratification and treatment selection. This requires simultaneous exploration of multiple genes of relevant networks to account for the complexity of mechanisms that govern drug sensitivity and predict clinical outcomes. We present the algorithm, Digital Display Precision Predictor (DDPP), aiming to identify transcriptomic predictors of treatment outcome. For example, 17 and 13 key genes were derived from the literature by their association with MTOR and angiogenesis pathways, respectively, and their expression in tumor versus normal tissues was associated with the progression-free survival (PFS) of patients treated with everolimus or axitinib (respectively) using DDPP. A specific eight-gene set best correlated with PFS in six patients treated with everolimus: AKT2, TSC1, FKB-12, TSC2, RPTOR, RHEB, PIK3CA, and PIK3CB (r = 0.99, p = 5.67E-05). A two-gene set best correlated with PFS in five patients treated with axitinib: KIT and KITLG (r = 0.99, p = 4.68E-04). Leave-one-out experiments demonstrated significant concordance between observed and DDPP-predicted PFS (r = 0.9, p = 0.015) for patients treated with everolimus. Notwithstanding the small cohort and pending further prospective validation, the prototype of DDPP offers the potential to transform patients' treatment selection with a tumor- and treatment-agnostic predictor of outcomes (duration of PFS).

Gastrointestinal stromal tumor: a review of current and emerging therapies

Gastrointestinal stromal tumors (GIST) are rare neoplasms arising from the interstitial cell of Cajal in the gastrointestinal tract. Two thirds of GIST in adult patients have c-Kit mutation and smaller fractions have platelet derived growth factor receptor alpha (PDGFRA) mutation. Surgery is the only curative treatment for localized disease. Imatinib improves survival when used adjuvantly and in advanced disease. Several targeted therapies have also improved survival in GIST patients after progression on imatinib including sunitinib and regorafenib. Recently, United States Federal and Drug Administration (FDA) approved two new tyrosine kinase inhibitors for the treatment of heavily pretreated advanced/unresectable GIST including avapritinib (a selective inhibitor for PDGFRA exon 18 mutation including D842V mutations) and ripretinib (a broad-spectrum kinase inhibitor of c-Kit and PDGFRA). In this article, we will provide a comprehensive review of GIST including the current standard of care treatment and exploring future paradigm shifts in therapy.

Human Pluripotent Stem Cells for Modeling of Anticancer Therapy-Induced Cardiotoxicity and Cardioprotective Drug Discovery

Anticancer chemotherapies have been shown to produce severe side effects, with cardiotoxicity from anthracycline being the most notable. Identifying risk factors for anticancer therapy-induced cardiotoxicity in cancer patients as well as understanding its underlying mechanism is essential to improving clinical outcomes of chemotherapy treatment regimens. Moreover, cardioprotective agents against anticancer therapy-induced cardiotoxicity are scarce. Human induced pluripotent stem cell technology offers an attractive platform for validation of potential single nucleotide polymorphism with increased risk for cardiotoxicity. Successful validation of risk factors and mechanism of cardiotoxicity would aid the development of such platform for novel drug discovery and facilitate the practice of personalized medicine.

SMARCB1/INI1-deficient tumors of adulthood

The SMARCB1/INI1 gene was first discovered in the mid-1990s, and since then it has been revealed that loss of function mutations in this gene result in aggressive rhabdoid tumors. Recently, the term "rhabdoid tumor" has become synonymous with decreased SMARCB1/INI1 expression. When genetic aberrations in the SMARCB1/INI1 gene occur, the result can cause complete loss of expression, decreased expression, and mosaic expression. Although SMARCB1/INI1-deficient tumors are predominantly sarcomas, this is a diverse group of tumors with mixed phenotypes, which can often make the diagnosis challenging. Prognosis for these aggressive tumors is often poor. Moreover, refractory and relapsing progressive disease is common. As a result, accurate and timely diagnosis is imperative. Despite the SMARCB1/INI1 gene itself and its implications in tumorigenesis being discovered over two decades ago, there is a paucity of rhabdoid tumor cases reported in the literature that detail SMARCB1/INI1 expression. Much work remains if we hope to provide additional therapeutic strategies for patients with aggressive SMARCB1/INI1-deficient tumors.

Ripretinib for the treatment of advanced gastrointestinal stromal tumor

Gastrointestinal stromal tumors (GISTs) are rare tumors of the gastrointestinal (GI) tract yet represent the most common GI sarcomas. Most GISTs are driven by activating mutations of the KIT and/or PDGFRA genes. Prior to the development of tyrosine kinase inhibitors (TKIs), GISTs were associated with a poor prognosis because conventional cytotoxic chemotherapy was relatively ineffective. However, TKIs that inhibit the most common driver mutations in KIT or PDGFRA have revolutionized the treatment of GISTs over the past two decades. Notwithstanding, ongoing management challenges relate to the development of secondary mutations in these genes, resulting in tumor progression. Due to both the intra- and inter-patient heterogeneity of these secondary mutations in GISTs, optimal treatment requires an agent that blocks as many mutant genes as possible. Ripretinib - a novel switch-control TKI - inhibits many of the most common primary and secondary activating KIT and PDGFRA mutants involved in GIST progression through a dual mechanism of action. In the pivotal INVICTUS phase III trial, patients with advanced GIST that had progressed on at least imatinib, sunitinib, and regorafenib and who received ripretinib experienced significantly longer progression-free survival (primary endpoint) as well as prolongation of overall survival, compared with those receiving placebo. Treatment with ripretinib was associated with durable improvements in quality-of-life indices and a manageable toxicity profile. The most frequent side effects were common to the class of TKIs used in the management of GIST. These results led to the approval of ripretinib for treatment of advanced GIST in adults who have received three or more TKIs, including imatinib. Ripretinib is also under investigation in the second-line treatment of advanced GIST in a phase III trial (INTRIGUE) comparing ripretinib with sunitinib in patients with advanced GIST after treatment with imatinib.

PLAIN LANGUAGE SUMMARY

Use of ripretinib for the treatment of gastrointestinal stromal tumors (GISTs) Gastrointestinal stromal tumors (GISTs) are a rare type of tumor most commonly located in the stomach and small intestine but can develop anywhere throughout the gastrointestinal tract. The symptoms of GISTs vary in extent depending on location of the primary tumor and include a feeling of fullness, abdominal pain, intestinal bleeding, and fatigue. Since these symptoms are nonspecific, making a diagnosis can be challenging. Most GISTs carry initial mutations in genes that control specific enzymes called tyrosine kinases. Historically, treatment of GISTs was limited because traditional chemotherapy is ineffective against these tumors. However, with the introduction of drugs that inhibit tyrosine kinases [i.e., tyrosine kinase inhibitors (TKIs)], survival has been extended substantially. However, many GISTs go on to develop secondary mutations that render them resistant to a given TKI. Prior to the approval of ripretinib, four TKIs were available for the treatment of GIST: imatinib; sunitinib; regorafenib; and, recently, avapritinib. Each drug is used until resistance develops or patients are unable to tolerate the side effects of treatment, after which the next drug is started. Ripretinib was recently approved by the FDA as the fourth drug in the usual treatment sequence recommended for patients with advanced GIST who have progressed (or are treatment intolerant) after receiving three or more TKIs, including imatinib. Approval of ripretinib was based on the results of the INVICTUS trial, which demonstrated that the drug significantly improves the time patients have without progression of the disease or death compared with placebo. The most common side effects related to ripretinib were hair loss, muscle pain, nausea, fatigue, hand-foot syndrome, and diarrhea, although most events were not very severe. Ripretinib is being further studied as the second TKI used in patients with GIST who have progressed on or could not tolerate first-line treatment with imatinib.

Discovery of novel potential KIT inhibitors for the treatment of gastrointestinal stromal tumor

Numerous inhibitors of tyrosine-protein kinase KIT, a receptor tyrosine kinase, have been explored as a viable therapy for the treatment of gastrointestinal stromal tumor (GIST). However, drug resistance due to acquired mutations in KIT makes these drugs almost useless. The present study was designed to screen the novel inhibitors against the activity of the KIT mutants through pharmacophore modeling and molecular docking. The best two pharmacophore models were established using the KIT mutants’ crystal complexes and were used to screen the new compounds with possible KIT inhibitory activity against both activation loop and ATP-binding mutants. As a result, two compounds were identified as potential candidates from the virtual screening, which satisfied the potential binding capabilities, molecular modeling characteristics, and predicted absorption, distribution, metabolism, excretion, toxicity (ADMET) properties. Further molecular docking simulations showed that two compounds made strong hydrogen bond interaction with different KIT mutant proteins. Our results indicated that pharmacophore models based on the receptor–ligand complex had excellent ability to screen KIT inhibitors, and two compounds may have the potential to develop further as the future KIT inhibitors for GIST treatment.