Role of Imaging in Response Assessment and Individualised Treatment for Sarcomas

Molecular Imaging in Soft-tissue Sarcoma: Evolving Role of FDG PET

Soft tissue sarcomas are a rare and heterogenous group of tumors that account for 2% of all cancer-related deaths. Molecular imaging with FDG PET can offer valuable metabolic information to help inform clinical management of soft tissue sarcomas that is unique and complementary to conventional diagnostic imaging techniques. FDG PET imaging often correlates with tumor grade, can help guide biopsy, and frequently detects additional sites of disease compared to conventional imaging in patients being considered for definitive or salvage therapy. Traditional size-based evaluation of treatment response is often inadequate in soft tissue sarcoma and changes in metabolic activity can add significant value to interim and end of treatment imaging for high-grade sarcomas. FDG PET can be used for detection of recurrence or malignant transformation and thus play a vital role in surveillance. This article reviews the evolving role of FDG PET in initial diagnosis, staging, treatment response assessment, and restaging. Further studies on the use of FDG PET in soft sarcoma are needed, particularly for rare histopathologic subtypes.

Exploratory analysis of tumor imaging in a Phase 2 trial with cabozantinib in gastrointestinal stromal tumor: lessons learned from study EORTC STBSG 1317 'CaboGIST'

BACKGROUND

Gastrointestinal stromal tumors (GISTs) are malignant mesenchymal tumors arising in the gastrointestinal tract. Their systemic treatment is based on the use of tyrosine kinase inhibitors (TKIs) with imatinib, sunitinib, and regorafenib being the preferred agents. Assessment of tumor response to TKI treatment in GISTs is traditionally done according the Response Evaluation Criteria in Solid Tumors (RECIST), while Choi criteria have also been proposed as alternative tool assessing both volumetric and density changes on computer tomography (CT) scans. EORTC STBSG 1317 'CaboGIST' was a single-arm prospective Phase 2 trial which met its primary endpoint, as 60% of patients previously treated with imatinib and sunitinib were progression-free at 12 weeks (95% CI 45-74%) based on local RECIST assessment.

MATERIALS AND METHODS

We report here an exploratory analysis of local versus central RECIST version 1.1 assessment and a comparison of RECIST version 1.1 versus Choi criteria.

RESULTS

Comparisons between local and central RECIST version 1.1 at week 12 revealed discrepancies in 17/43 evaluable cases (39.5%). When comparing Choi with local and central RECIST version 1.1, discrepancies were observed in 27/43 (62.8%) and 21/43 (48.8%) cases, respectively. A total of 68% of evaluable patients were progression-free and alive at week 12 based on local RECIST, 84% according to central RECIST analysis and 81% when applying Choi criteria. Central assessment upgraded the treatment response both with RECIST version 1.1 and Choi.

CONCLUSIONS

The results of this exploratory analysis support the conclusion that cabozantinib is active in patients with metastatic or recurrent GIST after treatment with imatinib and sunitinib and confirm once again the limitations of RECIST to capture response to TKI in GIST, and the importance to include density changes in the response evaluation in this setting. Clinical trial number: EORTC 1317, NCT02216578.

Current treatment strategies and future perspectives for gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors that originate from the gastrointestinal tract, mostly from the stomach. GISTs are derived from the myenteric interstitial cells of Cajal and are caused by several mutations in the c-kit and platelet-derived growth factor receptor genes. Clinically, GISTs are detected by endoscopic and imaging findings and are diagnosed by immunostaining. Surgery is the first line of treatment, and if the tumor is relatively small, minimally invasive surgery such as laparoscopy is performed. In recent years, neoadjuvant therapy has been administered to patients with GISTs that are suspected of having a large size or infiltration to other organs. Postoperative adjuvant imatinib is the standard therapy for high-risk GISTs. It is important to assess the risk of recurrence after GIST resection. However, the effect of tyrosine kinase inhibitor use will vary by the mutation of c-kit genes and the site of mutation. Furthermore, information regarding gene mutation is indispensable when considering the treatment policy for recurrent GISTs. This article reviews the clinicopathological characteristics of GISTs along with the minimally invasive and multidisciplinary treatment options available for these tumors. The future perspectives for diagnostic and treatment approaches for these tumors have also been discussed.

MRI Volumetrics and Image Texture Analysis in Assessing Systemic Treatment Response in Extra-Abdominal Desmoid Fibromatosis

Purpose To determine whether MRI volumetric and image texture analysis correlates with treatment-induced biologic changes in desmoid fibromatosis (DF) earlier than conventional response criteria. Materials and Methods This retrospective study included 27 patients with histologically proven extra-abdominal DF who were managed with active surveillance or systemic therapy (from 2004 to 2016). MRI volumetric and image texture parameters were derived from manual tumor segmentations, and tumor signal intensity was normalized to muscle. Results were compared with objective response rates based on Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1, World Health Organization (WHO) lesion response, volumetrics, and MRI-modified Choi criteria. Correlation coefficients (r) between image texture features and maximum tumor diameters were obtained by using a meta-analysis approach. Results The 27 included patients (mean age, 39 years; 74% women) were followed for an average of 4 years, comprising 207 distinct time-point assessments. The mean baseline tumor maximum diameter was 7.9 cm (range, 3.4-15.2 cm). Partial response (PR) rates as best response were 37%, 44%, 70%, and 81% by RECIST, WHO, volumetrics, and MRI-modified Choi criteria, respectively. Among the 10 tumors showing RECIST PR, a preceding MRI-modified Choi PR was observed in 70% (seven of 10), on average 1.3 years earlier. Multiple image texture parameters showed associations with objective measurements of tumor diameter including mean tumor-to-muscle signal ratio (r = 0.51; P = .004), median tumor-to-muscle signal ratio (r = 0.52; P = .003), energy (r = 0.48; P < .001), run entropy (r = 0.32, P = .04), and gray-level nonuniformity (r = 0.54; P ≤ .001). Conclusion Volumetric signal and image texture assessment allows more comprehensive analysis of DF biologic change and may permit early prediction of DF behavior and therapeutic response. Keywords: MR Imaging, Soft Tissues/Skin, Neoplasms-Primary © RSNA, 2021.

Multimodal functional imaging for early response assessment in patients with gastrointestinal stromal tumor treated with tyrosine kinase inhibitors

BACKGROUND

Several imaging modalities are used in the early work-up of patients with gastrointestinal stromal tumor (GIST) receiving tyrosine kinase inhibitor (TKI) treatment and there is a need to establish whether they provide similar or complimentary information.

PURPOSE

To compare 18F-fluorodeoxyglucose positron emission tomography (FDG PET), computed tomography (CT) and magnetic resonance imaging (MRI) as early predictors of three-month outcomes for patients with GIST receiving TKI treatment.

MATERIAL AND METHODS

Thirty-five patients with advanced GIST were prospectively included between February 2011 and June 2017. FDG PET, contrast-enhanced CT (CECT), and MRI were performed before and early after onset of TKI treatment (range 8-18 days). Early response was categorized according to mRECIST (CT), the Choi criteria (CECT), and PERCIST (FDG PET/CT). For MRI, volumetry from T2-weighted images and change in apparent diffusion coefficient (ADC) from diffusion-weighted imaging was used. The reference standard for early assessment was the three-month mRECIST evaluation based on CT. At three months, both stable disease (SD) and partial response (PR) were categorized as response. Clinical usefulness was defined as agreement between early and three-month assessment.

RESULTS

At the three-month assessment, 91% (32/35) were responders, 37% (13/35) PR, 54% (19/35) SD, and 9% (3/35) had progressive disease (PD). Early assessment correctly predicted three-month response in 93% (27/29) for MRI, 80% (28/35) for PERCIST, 74% (26/35) for Choi, and 23% (8/35) for mRECIST. Six patients had non-FDG-avid tumors. For the FDG-avid tumors, PET/CT correctly predicted three-month response in 97% (28/29).

CONCLUSION

MRI was superior to CECT for early assessment of TKI-treatment response in GIST. If the tumor was FDG-avid, PET and MRI were equally good. Changes in functional parameters were superior to changes in longest tumor diameter (mRECIST).

Immune checkpoint inhibitors in treatment of soft-tissue sarcoma: A systematic review and meta-analysis

BACKGROUND

Soft-tissue sarcomas (STSs) are rare malignancies, accounting for approximately 1% of adult cancer. Metastatic disease carries a poor prognosis, and various efforts have been made to improve the prognosis of advanced STS, to date with little success. Immune checkpoint inhibitors (ICPIs) have substantially improved prognosis for many cancer types. Their role in the treatment of STS, however, remains unravelled.

OBJECTIVE

The objective of the study is to assess the activity of ICPIs in the treatment of STS.

METHODS

We performed a systematic review using MEDLINE, Embase and Cochrane Central Register of Controlled Trials. Furthermore, abstracts from European Society of Medical Oncology (ESMO), American Society of Clinical Oncology (ASCO) and Connective Tissue Society Oncology (CTOS) congress were searched from 2017 until 2020. Prospective clinical trials investigating ICPIs, either monotherapy or combination therapy, in STS were available for inclusion. The outcomes of interest were objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), overall survival (OS) and major toxicity. Cut-off for clinical activity was defined as an ORR of ≥0.15. Subgroup analysis was carried out as per treatment category, disease setting and histologic subtype, using a random effects model.

RESULTS

We identified 27 studies, including a total of 1012 patients (range 6-85) with more than 25 histologic subtypes. The pooled ORR was 0.14 (95% confidence interval [CI] 0.09-0.18), DCR was 0.55 (95% CI 0.43-0.66), mean PFS range was 1.8-11.5 months and mean OS was 6.1-34.7 months. The pooled ORR as per treatment category was 0.14 for anti-programmed cell death 1 (anti-PD1) monotherapy (95% CI 0.07-0.23), 0.16 for anti-PD1 + anti-cytotoxic T-lymphocyte-associated protein 4 (95% CI 0.06-0.29), 0.20 for anti-PD1 + tyrosine kinase inhibitor (95% CI 0.06-0.38), 0.20 for anti-PD1 + chemo (95% CI 0.06-0.38) and 0.08 for anti-PD1 + immunomodulator (95% CI 0.01-0.19). The pooled ORR as per disease setting was as follows: neoadjuvant treatment, 0.09 (0.00-0.25); advanced disease first line, 0.23 (0.15-0.32) and advanced pretreated, 0.13 (0.09-0.19). High response rates were seen in classic Kaposi sarcoma (CKS), alveolar soft part sarcoma (ASPS) and undifferentiated pleomorphic sarcoma (UPS) with ORR of 0.69 (95% CI 0.51-0.82), 0.35 (95% CI 0.27-0.44) and 0.20 (95% CI 0.15-0.27), respectively. Activity was limited in gastrointestinal stromal tumour (ORR 0.01 [95% CI 0.0-0.08]), uterine leiomyosarcoma (ORR 0.06 [95% CI 0.02-0.18]), leiomyosarcoma (ORR 0.10 [95% CI 0.06-0.17]) and liposarcoma (ORR 0.11 [95% CI 0.07-0.17]).

CONCLUSION

Clinical activity of ICPIs in STS is highly variable and depends on histologic subtype, disease setting and concomitant treatment strategy. Activity was high in CKS, ASPS and UPS. Early incorporation of ICPIs in combination with chemotherapy seems a promising strategy that warrants further interest. Translational research integrating molecular profile, biological behaviour and response to ICPIs should determine their role in treatment of STS.

Hypofractionated Radiotherapy in Locally Advanced Myxoid Liposarcomas of Extremities or Trunk Wall: Results of a Single-Arm Prospective Clinical Trial

Introduction: Myxoid liposarcoma (MLPS) has been reported to be more radiosensitive compared with other soft tissue sarcomas. The main objective of the study was to assess the efficacy of hypofractionated radiotherapy (RT) in the preoperative setting in patients with locally advanced primary MLPS. Methods: Single-arm prospective exploratory clinical trial enrolled MLPS patients for preoperative 5 × 5 Gy RT with delayed surgery. The endpoints of the study were the rate of early wound healing complications and 5-year local control rate. Results: 29 patients (pts) were included, all had tumors located on the lower limb. The median maximum size of the tumor was 13 cm (IQR 10–15 cm). Early RT tolerance was good. Postoperative wound complications occurred in 11 pts (37.9%), late complications concerned 13.8% of patients. A total of 27 patients were included for the efficacy analyses. The pathological features of response to RT were detected in all analyzed surgical specimens. In 25 patients R0 margins were achieved, two patients had an R1 resection. None of the patients had local recurrence. Conclusion: Preoperative hypofractionated RT with a prolonged gap between RT and surgery is a feasible method of the management of MLPS, providing a good local control and low rates of treatment toxicity.

Functional image in soft tissue sarcomas: An update of the indications of 18F-FDG-PET/CT

Soft tissue sarcomas (STS) are a rare and heterogeneous group of tumors. They account for 1% of solid malignant tumors in adults and 7% in children and are responsible for 2% of cancer mortality. They require a multidisciplinary approach in centers with experience. This collaboration aims to update the scientific evidence to strengthen, together with clinical experience, the bases for the use and limitations of ¹⁸F-FDG-PET/CT in STSs. The general recommendations for the use of PET/CT in STS at present are summarized as the initial evaluation of soft tissue tumours when conventional image does not establish benignity with certainty and this determines the approach; in biopsy guiding in selected cases; in the initial staging, as additional tool, for rhabdomyosarcoma and STS of extremities or superficial trunk and head and neck tumours; in the suspicion of local recurrence when the CT or MRI are inconclusive and in the presence of osteosynthesis or prosthetic material and in assessment of therapy response to local/systemic therapy in stages ii/iii. In addition, PET/CT has the added value of being a surrogate marker of the histopathological response and it provides prognostic information, both in the baseline study and after treatment.

Update on systemic therapy for advanced soft-tissue sarcoma

Background

Soft-tissue sarcoma (sts) represents a rare group of mesenchymal neoplasms comprising more than 50 heterogeneous subtypes. Great efforts have been made to increase the understanding of the treatment of advanced sts (unresectable or metastatic disease). We set out to determine whether outcomes for patients with advanced sts have improved over time and to assess the current evidence for systemic therapy.

Methods

In a scoping review, we evaluated the contemporary evidence for systemic treatment of advanced sts in adults (>18 years of age). Phase i, ii, and iii studies of systemic therapy for advanced sts published in the English language were included. After abstract and full-text review of seventy-seven studies, sixty-two trials met the inclusion criteria.

Results

The number of clinical trials conducted and published in advanced sts has increased over the last 30 years. Although median overall survival has increased, attempts at improving first-line therapy through dose intensification, doublet chemotherapy, or alternative backbones have not been successful. The optimal therapy beyond anthracyclines remains a challenge, especially given the heterogeneity that grouping multiple sts subtypes within clinical trials creates. However, increasing numbers of agents are being studied, and several studies had shown isolated benefit in progression-free or overall survival.

Summary

First-line systemic therapy with an anthracycline remains the standard of care for advanced sts. However, choice of subsequent therapy beyond anthracyclines remains challenging. Novel systemic therapies, use of molecular diagnostics to direct therapy, subtype-specific trials, and learnings from real-world retrospective data are all important for improving outcomes in patients with advanced sts.

Prognosis assessment in metastatic gastrointestinal stromal tumors treated with tyrosine kinase inhibitors based on CT-texture analysis

PURPOSE

Identification of prognostic CT-textural features in patients with gastrointestinal stromal tumors undergoing tyrosine kinase inhibitor (TKI) therapy.

METHODS AND MATERIALS

We identified 25 GIST patients (mean age, 70.58 ± 9.7 years; range, 41.25-84.08 years; 20 males, 5 females) with a total of 123 scans, each examined with a standardized CT protocol between 1/2014-7/2018. 92 texture features, based on pyradiomics library, were extracted and correlated to response categories; evaluated with help of modified Choi criteria. All patients underwent therapy with imatinib in the first line and different tyrosine kinase inhibitors after disease progression. KIT and PDGFR-mutations were registered in all patients as well as the number of previous treatment regimens, patient's age as well as gender and the presence of contrast enhancement (vitality) in tumor. The lesion with the largest diameter was chosen and contoured using the spherical VOI tool. Inter-rater testing was performed by a second experienced radiologist. Regression and AUC analysis was performed.

RESULTS

Ten variables could be confirmed to be significantly associated with disease progression. Of them, four textural parameters were significantly positively associated with disease progression and negatively with progression free survival (Glcm Id [grey-level co-occurrence matrix inverse difference], p = 0.012, HR 3.83; 95% CI 1.697-8.611, Glcm Idn [grey-level co-occurrence matrix inverse difference normalized], p = 0.045, HR 2.06, 95% CI 1.015-4.185, Glrlm [grey-level run length matrix] normalized, p = 0.005, HR 3.181; 95% CI 1.418-7.138 and Ngtdm [neighboring grey-tone difference matrix] coarseness, p < 0.001, HR 3.156, 95% CI 1.554-6.411). Single variables were shown to be significantly inferior to the combination of all variables. After 6 months, 90% of patients with 0-1 risk factors (group 1), 64.4% with 2-3 risk variables and 38.1% of patients presenting > 3 structural risk variables showed stable disease. Gclm Id, Gclm Idn and Glrlm non-uniformity were associated with the number of previous treatments, Glrlm non-uniformity also with tumor vitality (enhancement), whereas Gclm Idn and Ngtdm coarseness were associated with the number of tumor mutations.

CONCLUSION

Some of the CT-textural features correlate with disease progression and the progressive free survival as well as with the number of gene mutations and the number of treatment regimens the patients were exposed to as well as with the tumor enhancement. All these features reflect tumor homogeneity.

Systemic Treatment of Metastatic/Recurrent Uterine Leiomyosarcoma: A Changing Paradigm

The treatment of metastatic and recurrent uterine leoimyosarcoma (uLMS) has evolved rapidly in the past several years. Leoimyosarcoma is extremely aggressive and responds poorly to traditional chemotherapeutics. Recent regulatory approval of novel treatment options has significantly expanded the therapeutic armamentarium, and the addition of these therapies has challenged clinicians to select and optimally sequence these new compounds. Additionally, the potential role of immunotherapy is being assessed in current uLMS clinical trials. Given the increasing number of agents available both in the U.S. and globally, a treatment template that addresses optimal sequencing based upon expert consensus would be useful. Current guidelines, although listing various options, lack granularity by line of therapy. Most patients with leiomyosarcoma, even in early stage, are treated with surgery followed by adjuvant chemotherapy despite uLMS being relatively chemoresistant. Adjuvant chemotherapy often includes the combination of gemcitabine and docetaxel with or without doxorubicin in first-line systemic therapy, but these cytotoxic agents only provide patients with advanced disease a 5-year survival <30%. This review will focus on examination of current guidelines and consensus building for optimal sequencing of systemic therapies for advanced or recurrent uLMS. Critical ongoing studies investigating novel approaches including immunotherapeutics and genetic alterations also will be discussed. IMPLICATIONS FOR PRACTICE: Recent regulatory approval of novel treatment options has significantly expanded the therapeutic armamentarium, and the addition of these therapies has challenged clinicians to select and optimally sequence these compounds. This review will focus on examination of current guidelines and consensus building for optimal sequencing of systemic therapies for advanced or recurrent uterine leoimyosarcoma.

Gastrointestinal stromal tumors: A multidisciplinary challenge

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors located in the alimentary tract. Its usual manifestation is gastrointestinal bleeding. However, small asymptomatic lesions are frequently detected as incidental finding. Characteristically, most GISTs (> 95%) are positive for the KIT protein (CD117) by IHC staining and approximately 80%-90% of GISTs carry a mutation in the c-KIT or PDGFRA genes. Mutational analysis should be performed when planning adjuvant and neoadjuvant therapy, due to its possible resistance to conventional treatment. The arise of tyrosine kinase inhibitor has supposed a revolution in GISTs treatment being useful as adjuvant, neoadjuvant or recurrence disease treatment. That is why a multidisciplinary approach to this disease is required. The correct characterization of the tumor at diagnosis (the diagnosis of recurrences and the evaluation of the response to treatment with tyrosine kinase inhibitors) is fundamental for facing these tumors and requires specialized Endoscopist, Radiologists and Nuclear Medicine Physician. Surgery is the only potentially curative treatment for suspected resectable GIST. In the case of high risk GISTs, surgery plus adjuvant Imatinib-Mesylate for 3 years is the standard treatment. Neoadjuvant imatinib-mesylate should be considered to shrink the tumor in case of locally advanced primary or recurrence disease, unresectable or potentially resectable metastasic tumors, and potentially resectable disease in complex anatomic locations to decrease the related morbidity. In the case of Metastatic GIST under Neoadjuvant treatment, when there are complete response, stable disease or limited disease progression, complete cytoreductive surgery could be a therapeutic option if feasible.

PET-CT evaluation of the curative effect of crizotinib on malignant myofibroblastoma with rare mutation of ALK R401: a case report and literature review

Objective

The purpose of this article is to explore the targeted treatment of malignant myofibroblastoma and evaluate the role of neoplasm metabolite markers in the evaluation of efficacy after targeted therapy.

Method

This report described a case of myofibroblastic sarcoma with rare mutation of ALK R401 in a 58-year-old man prescribed with crizotinib, to evaluate its curative effect by positron emission tomography coupled with computed tomography (PET-CT). After the progressive disease in the brain, bevacizumab combined with crizotinib was administered. The Response Evaluation Criteria in Solid Tumors (RECIST), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were used to assess the efficacy. The efficacy was assessed by comparing changes in MTV and TLG.

Result

After the treatment of crizotinib, the tumor volume was decreased. However, bevacizumab combined with crizotinib had not improved the prognosis. The change of MTV and TLG was consistent with the efficacy. The increase of MTV and TLG is an early indicator of the poor prognosis of patients.

Conclusion

The treatment of the crizotinib patient with the mutation of ALK R401 was effective. The values of MTV and TLG reflected the prognosis earlier than RECIST.

Nonconventional patterns of benefit of solid tumors treated with PD-(L)1 inhibitors: a systematic review

Aim: The use of immune checkpoint inhibitors in the treatment of solid tumors has been expanding recently. Standard response evaluation criteria are not well suited to evaluate the clinical benefit from these agents. To systematically review the incidence and characteristics of nonconventional patterns of benefit observed in solid tumors treated with immune checkpoint inhibitors. Materials & methods: MEDLINE and EMBASE databases have been searched. Moreover, reference lists of relevant articles were checked for cross-references. Selection criteria: Clinical studies evaluating PD-(L)1 inhibitors for the management of advanced solid tumors irrespective of the publication status or language. The review author extracted relevant data on the characteristics of participants and the outcomes of the different studies. Results: Nineteen prospective trials with 5404 participants were included. Among patients experiencing RECIST-defined progression and continued treatment beyond progression, rates of response beyond progression ranged from 4 to 10% (of the total number of included patients). These findings were similarly observed regardless of the PD-(L)1 inhibitor used, the disease treated, or the dose used indicating that these findings are part of the inherent characteristics of PD-(L)1 inhibitors for solid tumors. These findings need confirmation from the results of other prospective studies. Many additional ongoing trials were identified evaluating the use of PD-(L)1 inhibitors for the management of solid tumors. Conclusion: Traditional RECIST criteria are not suited for proper assessment of response to PD-(L)1 inhibitors; and more tailored criteria (e.g. immune-related response criteria) should be employed for patients treated with PD-(L)1 inhibitors; moreover in patients with an evidence of disease progression on initial disease evaluation, treatment should not be stopped except after confirmation of progressive disease with a second evaluation at least 4 weeks later.

Systemic Treatments in Soft Tissue Sarcomas

Systematic treatment of adult-type soft tissue sarcoma is evolving. Its role in the neoadjuvant setting is currently experimental, whereas the data on adjuvant chemotherapy are inconclusive. Nevertheless, in clinical practice, neoadjuvant and adjuvant chemotherapy may be considered on an individual basis after multidisciplinary discussion. Systemic therapy has a well-established role in the management of locally advanced and metastatic disease and histology-based treatment approaches are being studied.