A Pilot Study of Brentuximab Vedotin, Rituximab and Dose Attenuated CHP in Patients 75 Years and Older with Diffuse Large B-Cell Lymphoma

Older patients with hematologic malignancies are underrepresented on prospective clinical trials relative to the incidence of disease in this group (Kanapuru et al, 2020). There are few studies in diffuse large B-cell lymphoma (DLBCL) focused specifically on older patients. Rituximab and dose attenuated cyclophosphamide, doxorubicin, vincristine, and prednisone (R-miniCHOP) has been studied on a prospective trial in fit patients aged 80 years and older. Seventy-two percent of patients on this study completed 6 cycles of R-miniCHOP. The overall response rate (ORR) was 73%, and the 2-year progression free survival (PFS) was 47% (Peyrade et al, 2011). Novel regimens are needed to improve upon the efficacy of therapy while preserving tolerability. Brentuximab vedotin (BV) has demonstrated activity in relapsed and refractory DLBCL (Jacobsen et al, 2015) as well as in combination with chemoimmunotherapy (Svoboda, 2020). This study evaluates the feasibility of BV with dose attenuated chemoimmunotherapy.

Methods: Patients with both CD30 positive (cut off 1%) and CD30 negative DLBCL aged 75 years and older were enrolled on the study. Patients received six, 3-week cycles of BV 1.8 mg/kg, cyclophosphamide 400 mg/m2, doxorubicin 25 mg/m2, vincristine 1 mg and prednisone 40 mg/m2 days 1-5 (BV R-miniCHP). For the first cycle patients received BV and prednisone as a prephase starting one week prior to cycle 1. All patients received pegfilgrastim. All patients underwent geriatric assessments at screening, following prephase and at the end of treatment. The primary endpoint was feasibility of this regimen in older patients. The regimen was considered feasible if 71% of patients completed 6 cycles of treatment with a 90% confidence interval (CI)=(58.0, 90.6%). Secondary endpoints included toxicity, ORR and complete response (CR) evaluated by positron emission tomography, PFS and overall survival (OS). Response assessments used the Lugano Criteria (Cheson et al, 2014). PFS and OS were estimated using the Kaplan-Meier method.

Results: Twenty-two patients were enrolled and started prephase with BV and prednisone. Their baseline characteristics are summarized in the table. Seventy-seven percent (17/22) of patients completed 6 cycles of BV R-miniCHP. Reasons for not completing treatment included progressive disease in 2 patients, myocardial infarction, fatigue, and an unrelated injury in 1 patient each. Twenty-one patients were evaluable for response. ORR was 86% (18/21) in all patients, with 67% (14/21) achieving CR. In CD30 positive patients the ORR was 80% (8/10) and the CR rate was 70% (7/10). In CD30 negative patients the ORR was 91% (10/11) and the CR rate was 64% (7/11). With a median follow up of 23 months, median OS and PFS (figure) were not reached. The 2-year PFS was 60.6%, 90% CI=(40.0%, 76.1%), and the 2-year OS was 73.9%, 90% CI=(52.4%, 86.8%).

The most common adverse events (AEs) were fatigue (82%), anemia (50%), diarrhea (50%), dysgeusia (45%) and peripheral sensory neuropathy (45%). Grade ≥3 AEs seen in more than 2 patients included neutropenia (23%), fatigue (18%), pneumonia (18%), hypoxia (14%), thrombocytopenia (9%) and thromboembolism (9%). Grade ≥3 peripheral sensory neuropathy was seen in 9% of patients. There were two deaths in patients receiving study treatment. These included a myocardial infarction related to treatment, and a bowel obstruction secondary to disease progression. Three other patients have died in follow up with 2 secondary to disease progression and 1 due to an unrelated event.

Conclusions: The study met its primary feasibility endpoint with 77% of patients completing 6 cycles of therapy. This regimen was delivered safely in this population and toxicities were consistent with those reported in larger prospective studies with R-miniCHOP or ofatumumab and miniCHOP (Peyrade et al, 2011; Peyrade et al 2017). Peripheral neuropathy is a key AE of interest given the inclusion of BV and while nearly half of patients experienced some peripheral neuropathy, it was severe in only 9% of pts. The ORR and CR rate, as well as the 2-year PFS compare favorably to other prospective studies in a population that included patients with high clinical risk, histologic transformation, and double hit lymphoma. BV and R-miniCHP may be a feasible regimen in older patients, and warrants further study based on these preliminary data demonstrating clinical activity and tolerability.