Abstract 1500P
Background
Radiation therapy is an essential backbone for the management of patients (pts) with soft tissue sarcomas (STS) as part of a multimodal curative or palliative treatment. Concurrent therapy with external-beam radiation therapy (EBRT) and chemotherapy with doxorubicin and ifosfamide is in use as well but is associated with relevant toxicity. Gemcitabine is a known radiosensitizer and shows activity in STS.
Methods
A single-center, retrospective analysis of 30 patients (pts) with STS treated with concurrent EBRT and gemcitabine from Nov 2017 to Feb 2022 in a neoadjuvant (17 pts) or palliative setting (13 pts). Gemcitabine was administered at 150-300mg/m2 once weekly for the duration of the EBRT (50 Gy in 25 fractions over 5 weeks). In the group receiving neoadjuvant treatment, 6 pts had undifferentiated pleomorphic sarcoma (UPS) G3, 5 liposarcoma (LPS) G1-G3, 2 leiomyosarcoma (LMS) G2, 1 solitary fibrous tumor (SFT), 1 malignant peripheral nerve sheath tumor (MPNST) G2, endometrial stromal sarcoma (ESS) G3 and 1 rhabdomyosarcoma G3.
Results
17 pts received the combination therapy in the neoadjuvant setting being ineligible for a systemic treatment or in addition to it. The IUCC stage was IIIB/A in 13 pts, IV in 1pt, and IB in 3 pts. 12 pts had R0 resection and 5 pts R1. The tumor regression grade (TRG) was >90% in 6 of the 9 G3 STS (67%), 80% 2/9 G3 STS (22%). The TRG for the G2 STS (n=2) was 30% and 40% and for the G1 STS between 5 and 40 %. All pts treated in palliative setting had high-grade STS and responded to the treatment with partial remission or durable local control for symptomatic fast-growing lesions. The combination treatment was well tolerated with reversible skin toxicity, leukopenia and thrombopenia CTCAE grade I-II. As expected, no hair loss was observed as a relevant benefit for the pts’ quality of life.
Conclusions
The concurrent EBRT and gemcitabine as radiosensitizer in pts with STS is feasible and well tolerated. The treatment is an option for patients not eligible for neoadjuvant systemic treatment or in addition to it and in the palliative setting as well. It might be more potent as radiation only in achieving tumor regression and local control for high-grade STS, but this requires prospective study.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
P. Hohenberger: Financial Interests, Personal, Advisory Board: Pfizer, Roche, GSK; Financial Interests, Personal, Invited Speaker: PharmaMar, Lilly; Financial Interests, Personal, Other, Clinical Expert: Boehringer Ingelheim; Financial Interests, Personal, Invited Speaker, Clinical Expert: AstraZenneca; Financial Interests, Institutional, Funding, Clinical Trial: Siemens; Financial Interests, Institutional, Research Grant, Clinical Trial: Novartis; Financial Interests, Institutional, Other, Clinical Trial: BLU-Medicine; Financial Interests, Institutional, Other, Meeting sponsorship: Pekkip Oncology; Non-Financial Interests, , Invited Speaker: German SarcomaFoundation (DSS); Non-Financial Interests,Leadership Role: German Interdisciplinary Sarcoma Group (GISG), Interdisciplinary Working Party on Sarcomas (IAWS) of the German Cancer Society (DKG); Non-Financial Interests, , Advisory Role: German Cancer Aid (DKH), Committee on Health Technology Assessment, Sarcoma Patients EuroNet (SPAEN). M. Augustin: Financial Interests, Personal, Advisory Board: BMS, PharmaMar, Merck, Roche, MSD, Pfizer, IPSEN; Financial Interests, Institutional, Principal Investigator: BMS, MSD, PhamaMar, AstraZeneca, Exelixis, IPSEN, Pfizer; Financial Interests, Personal, Other: BluePrint Medicines, Janssen-Cilag. All other authors have declared no conflicts of interest.