A phase II study on the neo-adjuvant combination of pazopanib and radiotherapy in patients with high-risk, localized soft tissue sarcoma

Elderberry interaction with pazopanib in a patient with soft‑tissue sarcoma: A case report and literature review

Elderberry flower extract is marketed as an herbal supplement with purported benefits in boosting the immune system. The use of elderberry increased during the coronavirus pandemic. However, the interaction of elderberry with cytotoxic medicines has remained elusive. Pazopanib is a multikinase inhibitor approved for patients diagnosed with soft-tissue sarcoma. The present study reported on the case of a middle-aged woman diagnosed with localized intermediate-grade sarcoma of the left sartorius muscle who received neoadjuvant pazopanib with radiation therapy. The patient had no other medical comorbidities and only took over-the-counter (OTC) elderberry supplements for numerous years to 'boost' her immune system. She started pazopanib at 400 mg per os (PO) daily, which was increased to 800 mg PO daily after a week. By week three on pazopanib, the patient reported intense nausea and a number of loose stools, requiring anti-nausea medication. By the fourth week on pazopanib, laboratory tests showed grade 3 liver injury, as demonstrated by a fivefold rise in liver enzymes along with severe nausea and loose stools. All medications, including elderberry supplement, were stopped. Within two weeks of stopping all medicines, the liver enzymes started normalizing within two weeks and were normal by the end of four weeks. Pazopanib treatment was resumed without the recurrence of side effect. Pazopanib is metabolized in the liver via the cytochrome P 450 (CYP)3A4 enzyme pathway. Hence, potent inhibitors of CYP3A4 are avoided for concurrent use with pazopanib. Small in vitro studies on elderberry extracts have shown weak inhibition of CYP3A4. However, considering the wide usage of elderberry and the availability of mixed supplements OTC, it is essential to pursue clinical studies in cancer patients to understand the interactions of elderberry extracts with cytotoxic medicines. In this report, the scientific evidence behind the use of elderberry was reviewed and a hypothesis of its interaction with pazopanib was proposed.

Unraveling the Myth of Radiation Resistance in Soft Tissue Sarcomas

There is a misconception that sarcomas are resistant to radiotherapy. This manuscript summarizes available (pre-) clinical data on the radiosensitivity of soft tissue sarcomas. Currently, clinical practice guidelines suggest irradiating sarcomas in 1.8-2 Gy once daily fractions. Careful observation of myxoid liposarcomas patients during preoperative radiotherapy led to the discovery of this subtype's remarkable radiosensitivity. It resulted subsequently in an international prospective clinical trial demonstrating the safety of a reduced total dose, yet still delivered with conventional 1.8-2 Gy fractions. In several areas of oncology, especially for tumors of epithelial origin where radiotherapy plays a curative role, the concurrent application of systemic compounds aiming for radiosensitization has been incorporated into routine clinical practice. This approach has also been investigated in sarcomas and is summarized in this manuscript. Observing relatively low α/β ratios after preclinical cellular investigations, investigators have explored hypofractionation with daily doses ranging from 2.85-8.0 Gy per day in prospective clinical studies, and the data are presented. Finally, we summarize work with mouse models and genomic investigations to predict observed responses to radiotherapy in sarcoma patients. Taken together, these data indicate that sarcomas are not resistant to radiation therapy.

Current stand on systemic therapy in localized soft tissue sarcomas: a clinician's perspective

Soft tissue sarcomas (STS) are rare heterogenous tumors derived from mesenchymal tissue. While surgery represents the primary treatment modality, the high recurrence rates following surgery alone necessitate consideration for systemic therapy in high-risk sarcomas. Despite multiple trials and meta-analyses over the last 3 decades, the role of chemotherapy remains controversial. It is crucial to accurately identify patients with high-risk diseases who may benefit the most from adjuvant and/or neoadjuvant chemotherapy. There is renewed interest in the potential to improve outcomes in localized resectable STSs with the addition of targeted and immunotherapeutic strategies. The review presented here is a summary of current evidence on systemic therapy in resectable localized STSs of the trunk and extremities to facilitate clinician decision-making.

Biology and Management of High-Grade Myxofibrosarcoma: State of the Art and Future Perspectives

Myxofibrosarcoma (MFS) is one of the most common adult soft tissue sarcomas, typically arising in the extremities. Histologically, MFS is classified into three grades: low, intermediate, and high. Histological grades correlate with distant metastases and tumor-associated mortality. The diagnosis of MFS is challenging due to a lack of well-characterized immunohistochemical markers. High-grade MFS displays highly complex karyotypes with multiple copy number alterations. Recent integrated genomic studies have shown the predominance of somatic copy number aberrations. However, the molecular pathogenesis of high-grade MFS remains poorly understood. The standard treatment for localized MFS is surgical resection. The systemic treatment options for advanced disease are limited. This review provides an updated overview of the clinical and imaging features, pathogenesis, histopathology, and treatment of high-grade MFS.

Toxicity, normal tissue and dose-volume planning parameters for radiotherapy in soft tissue sarcoma of the extremities: A systematic review of the literature

BACKGROUND

Patients with soft tissue sarcoma of the extremities (STSE) are left with high incidence of toxicities after Radiotherapy (RT). Understanding the normal tissue dose relationship with the development of long-term toxicities may enable better RT planning in order to reduce treatment toxicities for STSE. This systematic review of the literature aims at reporting the incidence of acute and late toxicities and identifying RT delineation guidance the normal tissues structures and dose-volume parameters for STSE.

METHODS

A literature search of PUBMED-MEDLINE for studies that reported data on RT toxicity outcomes, delineation guidelines and dose-volume parameters for STSE from 2000 to 2022. Data has been tabulated and reported.

RESULTS

Thirty of 586 papers were selected after exclusion criteria. External beam RT prescriptions ranged from 30 to 72 Gy. The majority of studies reported the use of Intensity Modulated RT (IMRT) (27%). Neo-adjuvant RT was used in 40%. The highest long-term toxicities were subcutaneous and lymphoedema, reported when delivering 3DCRT. IMRT had a lower incidence of toxicities. Normal tissue outlining such as weight-bearing bones, skin and subcutaneous tissue, corridor and neurovascular bundle was recommended in 6 studies. Nine studies recommended the use of dose-volume constraints, but only one recommended evidence-based dose-volume constraints.

CONCLUSION

Although the literature is replete with toxicity reports, there is a lack of evidence-based guidance on normal tissue and dose-volume parameters and strategies to reduce the normal tissues irradiation when optimising RT plans for STSE are poor compared to other tumour sites.

Intra-Tumoral Pharmacokinetics of Pazopanib in Combination with Radiotherapy in Patients with Non-Metastatic Soft-Tissue Sarcoma

There is a lack of understanding whether plasma levels of anticancer drugs (such as pazopanib) correlate with intra-tumoral levels and whether the plasma compartment is the best surrogate for pharmacokinetic and pharmacodynamic evaluation. Therefore, we aimed to quantify pazopanib concentrations in tumor tissue, to assess the correlation between tumor concentrations and plasma concentrations and between tumor concentrations and efficacy. In this clinical trial, non-metastatic STS patients were treated with neo-adjuvant concurrent radiotherapy and pazopanib. Plasma samples and tumor biopsies were collected, and pazopanib concentrations were measured using liquid chromatography-tandem mass spectrometry. Twenty-four evaluable patients were included. The median pazopanib tumor concentration was 19.2 µg/g (range 0.149-200 µg/g). A modest correlation was found between tumor concentrations and plasma levels of pazopanib (ρ = 0.41, p = 0.049). No correlation was found between tumor concentrations and percentage of viable tumor cells (p > 0.05); however, a trend towards less viable tumor cells in patients with high pazopanib concentrations in tumor tissue was observed in a categorical analysis. Possible explanations for the lack of correlation might be heterogeneity of the tumors and timing of the biopsy procedure.