Bleomycin Use in the Treatment of Hodgkin Lymphoma (HL): Toxicity and Outcomes in the Modern Era

BACKGROUND: Historically, one in five Hodgkin Lymphoma (HL) patients treated with bleomycin develop bleomycin pulmonary toxicity (BPT), a life-threatening interstitial pneumonitis. The current treatment paradigm consists of prompt discontinuation of bleomycin, administration of corticosteroids, antibiotics, hospital admission, respiratory therapy, or intensive care. BPT represents a challenge for patients with HL as it not only impairs respiratory function, but also has negative impacts on clinical outcomes. A collection of a dozen studies suggest BPT has a mortality rate just short of 10% of patients who develop BPT. Given recent data on bleomycin omission with negative interim PET scan, we assessed changes in BPT rates and severity over the past 15 years. Overall, treatment protocol characterization and patient characteristics most responsive to BPT treatment are poorly understood.

OBJECTIVES: In this study, we investigated the clinical impact and treatment strategies in patients with BPT. Our goals were to: 1) Identify HL patients in the last decades who developed BPT and identify risk factors for BPT, 2) evaluate the impact of BPT on long-term clinical outcomes, and 3) characterize patterns of treatment strategies among patients with HL who develop BPT.

METHODS: A single-center, retrospective analysis was preformed using patient data from the Mayo Clinic Lymphoma Database (Rochester, MN) consisting of 1,299 patients diagnosed with HL. All patients were diagnosed between 2003-2018. Inclusion criteria included 1) newly diagnosed, biopsy proven HL, 2) upfront treatment with ABVD, 3) treatment was received at our institution. All patients were assessed for clinically relevant HL characteristics including stage of disease, presence of bulky disease, presence of B symptoms, Eastern Cooperative Oncology Group (ECOG) performance status, BPT risk factors, and bleomycin treatment regimen. BPT was clinically defined as 1) Presence of pulmonary symptoms, 2) bilateral interstitial infiltrates on imaging, and 3) no evidence of infectious etiology. Patients treated in the "Early Era" (2000s) were compared to patients in the "Recent Era" (2010s). Comparison of continuous variables between BPT groups was assessed with Wilcox rank-sum test. OS and PFS were estimated via the Kaplan-Meier method. Approval of the protocol by the Mayo Clinic Institutional Review Board (IRB) was obtained and all patients were consented accordingly.

RESULTS: One-hundred twenty six patients met the inclusion criteria for this study. Median follow-up for PFS and OS was 5.5 years (95%CI = 4.8-6.4) and 5.8 years (95%CI = 5.0-7.0), respectively. The 10-year OS and PFS among all patients were 85.1% (95%CI = 77.8-93.1) and 86.3% (95%CI = 80.1-93.0), respectively. Forty-seven patients (37% of all patients) met criteria for BPT. The estimated 10-year OS for BPT and non-BPT patients were 74.7% (95%CI = 61.8-90.5) and 91.7% (95%CI = 83.9-100.0), respectively. The estimated 10-year PFS for BPT and non-BPT patients were 84.7% (95%CI = 74.8-95.8) and 87.0% (95%CI = 79.1-95.8), respectively. In univariable analysis, BPT negatively impacted OS (HR=3.6, 95%CI: 1.2-10.6). However, bleomycin omission did not impact OS (HR=1.3, 95%CI=0.5-3.7). BPT-mortality was 17%. In multivariable analysis, BPT was not significantly associated with OS after adjusting for baseline characteristics (HR=3.0, 95%CI=0.9-9.9). Patients were older (median: 46 vs 33 years) and received less bleomycin (median: 107 vs 215 units) compared to non-BPT patients. BPT was most often managed with bleomycin omission with 59% of patients (74 of 126 patients) having omitted bleomycin at some point during treatment. Patients treated in the "Recent Era" (2010s) had lower BPT rates (28% vs 48%), mortality (10% vs 21%), bleomycin dose (143 vs 204 units), and bleomycin cycles (7 vs 12 cycles), yet higher prophylactic bleomycin omission (59% vs 8%) compared to "Early Era" (2000s). Patients treated in the Recent Era compared to Early Era had a reduction of BPT treatment with steroids, hospital admission, respiratory therapy, and ICU admission by 12%, 22%, 14%, 13%, respectively.

CONCLUSION: Overall, our data suggests BPT continues to impact OS in HL patients treated with ABVD, however BPT treatment is decreasing as management changed in recent years.