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733 PET-Driven Radiotherapy (RT) in Patients with Low Risk Diffuse Large B-Cell Lymphoma (DLBCL): 5-Year Results of the DLCL10 Multicenter Phase 2 Trial By Fondazione Italiana Linfomi (FIL)Clinically Relevant Abstract

Program: Oral and Poster Abstracts
Type: Oral
Session: 626. Aggressive Lymphomas: Prospective Therapeutic Trials: Frontline Treatment of Large B-cell Lymphoma
Hematology Disease Topics & Pathways:
Research, clinical trials, Clinical Research, Combination therapy, Therapies
Monday, December 12, 2022: 10:30 AM

Monica Balzarotti, MD1*, Umberto Ricardi, MD2*, Michele Spina, MD3, Andrea Evangelista, MSc4*, Alessandra Tucci, MD5*, Federica Cavallo, MD6*, Manuela Zanni, MD7*, Annalisa Arcari, MD8*, Vittorio Ruggero Zilioli, MD9*, Roberto Sartori, MD10*, Francesco Merli, MD11*, Francesca Re, MD12*, Umberto Vitolo, MD13, Maria Assunta Deidda, MD14*, Luca Melis, MD15*, Daniela Dessì, MD16*, Marcello Rodari, MD17*, Armando Santoro, MD18*, Gianluca Gaidano, MD, PhD19, Giovannino Ciccone, MD20*, Stephane Chauvie, PhD21* and Maria Giuseppina Cabras, MD16*

1Department of Hematology, Humanitas Clinical and Research Center IRCCS, Rozzano, Italy
2Radiation Oncology, Department of Oncology, University of Turin, Turin, ITA
3Dept of Medical Oncology, IRCCS CRO Aviano, Aviano (PN), Italy
4Città Della Salute E Della Scienza, Torino, ITA
5Department of Hematology, ASST Spedali Civili, Brescia, Italy
6Division of Hematology , AOU Città della Salute e della Scienza di Torino, Torino, Italy
7Division of Hematology, Azienda Ospedaliera Santi Antonio e Biagio e Cesare Arrigo, Alessandria, Italy
8Hematology Unit, Ospedale Guglielmo da Saliceto, Piacenza, Italy
9Division of Hematology, ASST Grande Ospedale Metropolitano Niguarda, Milan, IT-MI, Italy
10Ospedale di Castelfranco Veneto - Ematologia, Castelfranco Veneto, ITA
11AUSL-IRCCS, Reggio Emilia, Reggio Emilia, Italy
12Hematology and CTMO, Azienda Ospedaliera-Universitaria di Parma, Parma, Italy
13Candiolo Cancer Institute, FPO-IRCCS, Candiolo (Torino), Italy
14Department of Radiotherapy, Regional Oncological Businco Hospital, Cagliari, Italy
15Ospedale Oncologico "A. Businco" Cagliari ·, Nuclear Medicin Unit, Cagliari, Italy
16Division of Hematology, Ospedale Oncologico Armando Businco, Cagliari, Italy
17Nuclear Medicine, IRCCS Humanitas Research Hospital, Milano, Italy
18Humanitas University and IRCCS Humanitas Research Hospital, Humanitas Cancer Center, Milan, Italy
19Division of Hematology, Department of Translational Medicine, Università del Piemonte Orientale, Novara, Italy
20Unit of Clinical Epidemiology, Azienda Ospedaliera e Universitaria Città della Salute e della Scienza and CPO Piemonte, Torino, Italy
21Medical Phyhsics Department, S. Croce Hospital, Cuneo, Italy

Background Recent data show that RT on PET-negative sites after chemo-immunotherapy in early stage DLBCL can be avoided. Nevertheless, bulky sites at diagnosis are still irradiated after rituximab-chemotherapy (R-CT), whereas residual uptake area (RUA at other sites are considered as failure. As PET negativity is mandatory to define complete remission (CR), we hypothesized that PET-neg areas after R-CT do not need consolidation RT independently from their size at onset

Aims: To assess the role of RT in PET-neg and in PET-pos low-risk DLBCL patients after R-CT

Methods: The DLCL10 protocol was a phase II study of patients (pts) >=18 years with low risk DLBCL according to the MiNT trial, (aa IPI 0 and bulky, aa IPI 1 +/- bulky) conducted in 19 FIL centers. Pts were treated with 6 courses of RCHOP and final response was evaluated with FDG-PET. Both pre and post treatment PET scans were centrally reviewed through the Widen web platform by a panel of 5 nuclear medicine experts. Positive scans were those centrally classified with Deauville score 3-4-5 by the first 2 concordant reviewers. Pts with one RUA received RT, 36 Gy involved-site, regardless of bulky disease at onset, while those with multiple RUA were shifted to salvage systemic therapy. Primary aim was to obtain a 2-year PFS of at least 85% for post R-CT PET-neg pts. Secondary endpoints were OS and response.

Results: From January 2012 to December 2017, 115 consecutive pts were screened, and 110 were evaluable. Median age 58 years (47-65); M:F 61 /49; DLBCL de novo 90%, aa IPI 0 16 , aa IPI 1 94 (20% with bulky mass), bulky disease in the whole series 35 pts ; RCHOP-14 /RCHOP-21 73/37. At the time of the present analysis median follow-up was 63 months and 13 pts died (3 lymphoma, 2 acute toxicitiy, 2 late toxicity, 2 secondary neoplasm, 2 complication from allo-transplant, 1 other causes, 1 unknown). A total of 105 pts completed the R-CT program, while five were discontinuated for lymphoma progression (1), toxicity (2, both died), histological review (1) and patient dispersion (1). At end of treatment, 83 patients had PET-neg, whereas 17 had single RUA and received involved -site RT. In PET-neg patients, PFS was 90.6% (95% CI 81.1-95.4) at 2 years and 82.48% (95% CI 78.4-94.3) at 5 years. OS was 96.37% (95% CI 89.17-98.81) at 2 years and 87.81% (95% CI 77.62-93.54) at 5 years. After RT, 15 pts reached CR, one PR and one was not evaluable. None of them relapsed. Thus, all patients with positive focal RUA after R-CT were cured with involved-site RT. Concerning the 35 pts with bulky disease, 21 reached PET-neg and 14 had single RUA after R-CT and were thus irradiated (1 PD). There were two relapses in the PET-neg/not irradiated group, but only one in previously bulky site. In the PET-pos /RT group no relapse occurred. In the total population, 5 -year PFS and OS are 80.9% (95%, CI 79.28-92.18) and 87.1% (95%, CI 78.66- 92.38), respectively.

Conclusion: Our data suggest that irradiating only sites of unique PET RUA, regardless of bulky at onset, can be considered as a reasonable strategy for low risk DLBCL pts. In cases with bulky disease, PET-driven RT allowed RT sparing in approximately half of patients in this small series. Moreover, consolidation RT in those with focal residual PET positivity, guaranteed excellent prognosis (17/17 cured) and can be considered as a valid option

Disclosures: Balzarotti: Servier: Membership on an entity's Board of Directors or advisory committees; Gentili: Membership on an entity's Board of Directors or advisory committees; Astrazeneca: Honoraria; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Gilead: Honoraria; Takeda: Honoraria. Tucci: Janssen: Membership on an entity's Board of Directors or advisory committees; MSD: Honoraria; Sanofi: Membership on an entity's Board of Directors or advisory committees; Gentili: Membership on an entity's Board of Directors or advisory committees; Kiowa Kyrin: Honoraria; Takeda: Honoraria. Cavallo: Amgen: Other: Expenses for EHA virtual meeting; Roche: Membership on an entity's Board of Directors or advisory committees, Other: Expenses for Ash meeting; Takeda: Other: Expenses for ICML virtual meeting; Servier: Speakers Bureau. Zilioli: Gentili: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees, Other: travel expenses, Speakers Bureau; Gilead: Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy; MSD: Membership on an entity's Board of Directors or advisory committees; Janssen: Other: travel expenses, Speakers Bureau. Vitolo: AbbVie, Incyte, Janssen, Gilead Sciences: Speakers Bureau; Seagen, Genmab, Incyte, Costellation, Bayer, Regeneron: Consultancy. Santoro: AstraZeneca: Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Eli-Lilly: Speakers Bureau; Sandoz: Speakers Bureau; Eisai: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Speakers Bureau; Bayer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Merck Sharp & Dohme: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Speakers Bureau; Gilead: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Servier: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Speakers Bureau; Abb-vie: Speakers Bureau; Amgen: Speakers Bureau; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda: Speakers Bureau; Incyte: Consultancy; Sanofi: Consultancy. Gaidano: Astra-Zeneca: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Beigene: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

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