736P - Residual masses after salvage chemotherapy in men with metastatic seminoma: The Semi-ResMass multicenter retrospective study

Background

Only limited data exist on the management of residual masses in men who have received two lines of chemotherapy for advanced seminoma. Therefore, the role of FDG PET/CT scans, surgery and other additional treatments remains controversial in these men.

Methods

Data from men with pure seminoma and residual masses after salvage chemotherapy were retrospectively collected from 13 high-volume centers. We analyzed the clinical management of residual masses (imaging, surgery, pathological data, and additional treatment modalities) and long-term outcomes. Residual mass was defined as a lesion of ≥1 cm after two lines of platinum-based chemotherapy.

Results

Data from 92 patients (pts) with non-progressing residual masses after second-line chemotherapy have been collected and have been included in this analysis. A post-chemotherapy FDG PET/CT was performed in 54 (59%) pts. Viable seminoma was found in 3/12 pts who had a biopsy (bio+). Surgery was performed in 47 (51%) pts, irrespectively of FDG uptake (no=8, yes=16). Complete necrosis was found in 42 (89%), viable seminoma in 3 (6%), teratoma in 1, and leiomyoma in 1 pt, respectively. No viable tumor cells were found in 8 men with a negative PET (PET-) who underwent surgery (2bio+). 16/28 pts with a positive PET (PET+) underwent surgery: 12 complete necrosis, 2 viable seminoma, 1 teratoma, and 1 leiomyoma. Among those with a PET+, 5/28 pts (18%) experienced either viable seminoma in residual subsequent relapse. A second relapse occurred in 13/92 (14%). Only 4/47 (8%) pts who had residual masses resected post 1^st salvage chemotherapy subsequently relapsed (3 had viable seminoma in the residuals). At a median follow-up of 4.35 years, 88 (92%) pts were alive. 4/92 patients died of cancer progression.

Conclusions

Most men with seminoma residual masses after 1^st salvage chemotherapy may achieve a cure. Pending validation with more pts in this rare situation, FDG PET/CT may help guide the selection of post-chemotherapy resection candidates. PET/CT appears of high negative predictive value when negative (100% [95%CI 63-100]), while PET+ scans have a remarkable risk of being false positive (positive predictive value 16% [95%CI 3-40]).

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

G. Baciarello: Financial Interests, Personal, Invited Speaker: Astellas; Financial Interests, Institutional, Steering Committee Member: Bayer; Non-Financial Interests, Principal Investigator: Roche, Eli Lilly, MSD; Non-Financial Interests, Member: ASCO. U.F.F. De Giorgi: Financial Interests, Personal, Advisory Board: Pfizer, BMS, MSD, PharmaMar, Astellas, Bayer, Ipsen, Novartis, Eisai, Janssen; Financial Interests, Personal, Invited Speaker: Roche, BMS, Clovis Oncology, AstraZeneca; Financial Interests, Institutional, Research Grant: AstraZeneca, Sanofi, Roche. G. Gravis: Financial Interests, Institutional, Invited Speaker: AAA, Amgen, Astellas, BMS, Janssen, MSD, Pfizer, Ipsen, AstraZeneca, alliance Merck Pfizer, Bayer, EISAI; Financial Interests, Institutional, Advisory Board: Alliance Merck-Pfizer, BMS, Janssen, Pfizer, Ipsen, Bayer, Eisai; Non-Financial Interests, Principal Investigator: BMS, Ipsen, Merck; Financial Interests, Institutional, Funding: Janssen; Financial Interests, Institutional, Coordinating PI: BMS. F. Morelli: Financial Interests, Personal, Invited Speaker: Astellas, Ipsen; Financial Interests, Personal, Advisory Board: Pfizer. D. Pouessel: Financial Interests, Personal, Invited Speaker: Ipsen, Bristol-Myers-Squibb, AstraZeneca, Astellas Pharma, MSD Oncology, Pfizer / Astellas; Financial Interests, Personal, Advisory Board: Astellas Pharma, Pfizer, MSD Oncology, Bristol-Myers-Squibb, Merck; Financial Interests, Institutional, Local PI: Merck Sharp & Dohme, Roche, Bristol-Myers-Squibb, AstraZeneca, Seagen. C. Oing: Financial Interests, Personal, Invited Speaker, Renal Cancer Expert Panel Case Presentation: Ipsen; Financial Interests, Personal, Invited Speaker, Talk on Pain Management in GU Cancer Patients: Medac; Financial Interests, Personal, Invited Speaker, Case Presentation Soft Tissue Sarcoma: Roche; Financial Interests, Personal, Advisory Board, Ad Board on discussing novel educational events for young haematologists: Novartis; Financial Interests, Personal, Invited Speaker, Science Slam with a presentation on young professional support from oncological societies in Germany: AstraZeneca; Financial Interests, Personal, Advisory Board, AdBoard assessing educational needs for oncology professionals regarding G-CSF use: Sandoz; Financial Interests, Personal, Invited Speaker, Presentation on Burnout and Resilience in medical oncology professionals: Asklepios Hamburg; Financial Interests, Personal, Advisory Board, Larotrectinib use in sarcoma: Bayer; Financial Interests, Personal, Advisory Board, Experiences with Cabo/Nivo as first-line treatment for metastatic RCC: Ipsen; Non-Financial Interests, Other, Clinical Advisory role in early drug discovery with a fellowship position affiliated with Astex Pharmaceuticals, Cambridge, UK: Astex Pharmaceuticals; Non-Financial Interests, Institutional, Product Samples, Cytotoxic Agent for Preclinical Experiments: PharmaMar. S. Ladoire: Financial Interests, Personal, Advisory Board, advisory board: Pfizer, Novartis, AstraZeneca, Sanofi, Daiichi Sankyo, Gilead, Menarini-Stemline; Financial Interests, Personal, Advisory Board, advisory board, expert testimony: Astellas; Financial Interests, Personal, Advisory Board, expert testimony, invited speaker: Janssen, Ipsen; Financial Interests, Personal, Invited Speaker, invited speaker: BMS, Seagen, Exact Science; Financial Interests, Personal, Invited Speaker, invited speaker, expert testimony: Lilly; Financial Interests, Institutional, Research Grant, research grant: Novartis, Eisai, BMS. K. Fizazi: Financial Interests, Institutional, Advisory Board: Astellas, Bayer, Janssen, AAA, MSD, AstraZeneca, Novartis/AAA, Pfizer, Daiichi Sankyo; Financial Interests, Institutional, Invited Speaker: Astellas, Bayer, Janssen, Sanofi, MSD, AstraZeneca, Novartis, Pfizer; Financial Interests, Personal, Advisory Board: Curevac, Orion; Financial Interests, Personal, Advisory Board, February 2022: Arvinas; Financial Interests, Personal, Advisory Board, April 2022: Macrogenics; Financial Interests, Institutional, Research Grant, Trial chair: Pfizer, Bayer, AstraZeneca, Orion, MSD, BMS, Janssen; Non-Financial Interests, Principal Investigator, Chair of the 7DX phase 3 trial: BMS; Non-Financial Interests, Principal Investigator, Chair of the Docetaxel-pembrolizumab phase 3 trial: Merck; Non-Financial Interests, Principal Investigator, Chair of the Darolutamide BCR phase 3 trial: Bayer; Non-Financial Interests, Principal Investigator, Chair of the PSMAfore phase 3 trial: AAA/Novartis; Non-Financial Interests, Principal Investigator, Chair of the CYPIDES ODM-208 Phase I-II trial: Orion; Non-Financial Interests, Principal Investigator, Chair of the STESIDES ODM-209 Phase I-II trial: Orion; Non-Financial Interests, Principal Investigator, Chair of the CAPITELLO 281 phase 3 trial: AstraZeneca; Non-Financial Interests, Principal Investigator, Chair of the TALAPRO-2 and TALAPRO-3 phase 3 trials: Pfizer; Non-Financial Interests, Principal Investigator, Chair of the RADIANT phase 3 trial: Bayer; Non-Financial Interests, Principal Investigator, Chair of the TRITON-3 phase 3 trial: Clovis. All other authors have declared no conflicts of interest.