A Multicenter Real-Life Study of Polatuzumab Vedotin Combined with Immunochemotherapy in Patients with R/R DLBCL: Preliminary Data on Efficacy and Safety in Chinese Cohort

Background

For patients with relapse/refractory(R/R) Diffuse Large B Cell Lymphoma (DLBCL), intensive therapy (such as R-ICE, R-DHAP) followed by autologous stem cell transplant (ASCT) can provide potential cure. However, not all patients would be eligible for such aggressive therapy. The ASCT ineligible or patients have very low survival rates and no curative options. Polatuzumab vedotin (Pola) is a conjugated antibody that delivers the microtubule inhibitor MMAE to CD79b-expressing cells. Pola administered in combination with Bendamustine-Rituximab (P-BR) has been approved for R/R DLBCL patients in USA and Europe consecutively. But real-life data of Pola on efficacy and safety in this setting especially in Chinese patients remain very limited.

Aim

This study aims to investigate the efficacy and tolerability of Pola with BR or R in R/R patients with DLBCL treated through a Compassionate Use Program (CUP) after failing ≥2 prior regimens.

Methods

We collected and analyzed the data of all patients enrolled in Pola CUP in four Chinese centers. Patients with R/R DLBCL who have exhausted all therapeutic options after at least 2 prior treatments could be enrolled in this program. Pola was administered at a dose of 1.8 mg/kg/cycle iv in combination with rituximab±bendamustine for a total of up to 6 cycles. Response was assessed after every 2 cycles and at end of treatment.

Results

From Dec 12 2019 to Jul 30 2020, 27 patients were treated in the CUP of Pola and there are 20 patients whose diseases had already been assessed at least once for the response evaluation. Baseline characteristics of the 20 patients are shown in Table1. Nine patients received Pola-BR combination and 3 of them received the bendamustine combined regimen after the 3^rd or 4^th cycle in order to improve the efficacy. For the other 11 patients only Pola-R was administered. All patients received rituximab in front lines and 80.0%(16/20) of them are refractory to the prior therapy (no response or relapsed≤6 mon). 70.0% (14/20) patients had a high-intermediate or high risk disease (IPI score≥3); 10.0% (2/20) had ECOG performance status (PS) 3-4. 25.0% (5/20) patients had already received prior Car-T and 5.0% (1/20) had prior ASCT therapy.

At time of analysis, six patients finished all 6 cycles of treatment and 3 discontinued therapy due to personal reason or disease progression. The remaining patients are still in the process of treatment. The achieved overall response was Complete Response (CR) in 1 patients (5.0%) and Partial Response (PR) in 15 patients (75.0%). One patient progressed after 2 cycles of Pola-R therapy, but achieved PR after receiving Bendamustine combined therapy from the 3^rd cycle. The overall response rate and treatment duration is shown in table 2 and Figure 1. The median follow-up is 48 days and the progression free survival (PFS) of the two progressed patients is 29 and 148 days. (Table 3 & Figure 2).

The main toxicity was hematological. Four patients developed grade 3-4 neutropenia (20.0%) and 2 patient (10.0%) had grade 3-4 thrombocytopenia. Febrile neutropenia was reported in 2 patients. One patient had pneumonia but recovered after anti-infection therapy. The adverse event of peripheral neuropathy was not observed.

Conclusion

For this R/R DLBCL cohort with heavily treated, high risk and refractory diseases, the Pola-(B)R regimen still achieved promising efficacy. However considering the limited sample size and short follow-up, more mature data and long-term survival outcomes is warrant.

Key words

Relapse/refractory; DLBCL; Polatuzumab Vedotin; Compassionate Use