CALGB 50801 (Alliance): PET adapted therapy in bulky stage I/II classic Hodgkin lymphoma (cHL).
Authors: LaCasce Ann S. , Dockter Travis , Ruppert Amy S. , Kostakoglu Lale , Schöder Heiko , Hsi Eric D. , Bogart Jeffrey A , Cheson Bruce D. , Wagner-Johnston Nina D. , Abramson Jeremy S. , Maddocks Kami J. , Leonard John Paul , Bartlett Nancy L. 
Published: June 2021

7507 Background: Bulky disease is associated with inferior outcomes in patients with early stage cHL. Historically, most patients (pts) receive chemotherapy followed by radiotherapy (RT), which is associated with long-term toxicity. We tested a PET-adapted approach to reduce the need for RT in pts with early PET-negative (PET-) disease and escalate therapy in pts with PET-positive (PET+) disease. Methods: Eligible pts aged 18-60 years (yrs) had stage IA-IIB cHL with disease bulk >10 cm or >.33 max intrathoracic diameter on chest x-ray. Pts received 2 cycles of doxorubicin-bleomycin-vinblastine-dacarbazine (ABVD) followed by centrally reviewed PET. PET- was defined as Deauville of 1-3. Pts who achieved a negative PET scan (PET2-) received 4 additional cycles of ABVD. PET2+ pts received 4 cycles of escBEACOPP plus 30 Gy involved-site radiation therapy. The primary endpoint was progression-free survival (PFS) estimated from PET2. With 93 pts and assuming 30% PET2+, there was 80% power to rule out that PFS of PET2+ pts was substantially inferior to PFS of PET2- pts (HR 4.1, 3-yr PFS 40% vs 80%) if the true PFS of PET2+ pts was closer to that of PET2- pts (HR 2.29, 3-yr PFS 60% vs 80%) with one-sided alpha=0.15. With few events and mature follow-up, we report results 3 yrs after the last pt was enrolled. Results: Between May 2010 and October 2017, 101 pts enrolled. Excluding 6 ineligible pts (3 without baseline DLCO, 2 did not meet definition of bulk, 1 stage IIIB) and 1 pt without PET2, 94 were evaluable. 78% of pts were PET2- (73 PET2-, 21 PET2+). Median age was 30 yrs (range: 18 to 58) and 53.2% were female. Distribution of stage was: 1A - 7.4%, IB - 2.1%, IIA – 39.4%, IIB - 51.1%; 61.9% PET2+ pts had stage IIB disease. Therapy was generally well tolerated. Grade > 3 neutropenia occurred in 86% of pts with 8% of PET2- and 10% of PET2+ with grade > 3 febrile neutropenia. 3-yr PFS estimates were 93.1% (95% CI: 87.4-99.1%) in PET2- pts, 89.7% (95% CI: 77.2-100.0%) in PET2+ pts (HR=1.01, 85% upper bound 2.32), and 92.3% (95% CI: 87.0-98.0%) for all pts. The protocol-defined primary endpoint was met as the PFS hazard ratio for PET2+ vs PET2- was less than 4.1 (one sided p=0.04). With a median follow-up of 5.5 yrs, 3 PET2- pts died (HL, anaplastic astrocytoma and COPD) and 1 PET2+ died of progressive disease. 3-yr overall survival (not a primary or secondary outcome of the study) estimates were 98.6% (95% CI: 95.9-100.0%) in PET2- pts, 94.4% (95% CI: 85.4-100.0%) in PET2+ pts (HR: 1.2, 95% CI: 0.12, 11.60), and 97.7% (95% CI: 94.7-100.0%) for all pts. Conclusions: Excellent PFS outcomes were observed in all pts using a PET-adapted approach that allowed omission of RT in 78% of pts. In addition, PET2+ pts treated with escalation to BEACOPP and consolidative RT did not have inferior outcomes. Support: U10CA180821, U10CA180882; https://acknowledgments.alliancefound.org ; ClinicalTrials.gov Identifier: NCT01118026. Clinical trial information: NCT01118026.