Selinexor in Combination with Salvage Regimen for Refractory Diffuse Large B-Cell Lymphoma (DLBCL) Patients with TP53 Alterations

Background

TP53 has been identified as one of the most frequently altered gene in diffuse large B-cell lymphoma (DLBCL). The prognosis of DLBCL patients with TP53 mutations ( TP53^mut) was poor prognosis in R-CHOP era, even with treatments like autologous stem-cell transplantation (ASCT) or anti-CD19 chimeric antigen receptor T-cell (CAR-T) therapy. Moreover, TP53 mutations are more prevalent at relapse and are associated with therapeutic resistance. Selinexor is a selective inhibitor of nuclear export with promising anti-cancer properties and preclinical studies have shown its potential to suppress tumor cells with TP53 mutations. Several clinical studies proved selinexor in combination with R-GDP/R-ICE/R-Gemox was effective in relapsed/refractory DLBCL.

Method

The study enrolled relapsed/refractory DLBCL patients with TP53 alterations (including TP53 mutation and/or deletion) for treatment with selinexor in combination with salvage regimens (R-GDP/R-ICE/R-Gemox) since November 2021 in our center. The treatment was administered orally as 40 mg of selinexor on days 1, 8, and 15, combined with one of the following regimens: R-GDP (R 375mg/m2 d0, gemcitabine 1g/m2*d1, cisplatin 25mg/m2 d1-d3, dexamethasone 40mg d1-d4). R-ICE (R 375mg/m2 d0, ifosfamide 1.5g/m2*3d, carboplatin (AUC 5) and etoposide 100mg/m2*3d). R-Gemox ((R 375mg/m2 d0, gemcitabine 1g/m2*d1, oxaliplatin 100mg/m2*d1) every 3 weeks as per physician's choice. Objective response rate (ORR) was evaluated every 3 cycles based on Lugano 2014 criteria and Adverse events (AE) were rated according to the NCI CTCAE 5.0.

Results

20 patients were treated with selinexor plus salvage regimen in this study and received at least two cycles of treatment, making them eligible for analysis. The median age of the 20 patients was 54 years (range 15 to 77), of this patients, 12 (60%) were male, 12 (60%) patients had disease stage III-IV at screening, and 45% with IPI>2. The median number of prior regimen was 1 (range, 1-4) with 2 patients (2 L) and 1 patient (3L). ALL patients were refractory to the last line of treatment. The patients received a median of three cycles (range, 2-6) of selinexor 40mg once a week combined with salvage regimen (13 patients received selinexor plus R-GDP, 6 with selinexor plus R-ICE and 1 with selinexor plus R-Gemox). The mutational profile of patients was presented in Figure A (14 patients with TP53 mutation, 5 patients with TP53 mutation and deletion, 1 with TP53 deletion).

The best overall and complete response rates were 75% and 25%, respectively. Among them, 6 patients in PR and 1 patient in SD received CART treatment, and 5 achieved PR and 2 with CR after CART treatment (Figure B). One patient experienced PD after selinexor+R-GDP and died of disease progression within one month after CART transfusion. 1 SD patient transferred to CD3/CD20 bispecific antibody clinical trial and still progressed during the bispecific treatment. Taken together, selinexor-based salvage regimen had promising response rate in refractory DLBCL with TP53 alterations, and could be a potential bridging approach before CART therapy. Patients responded to selinexor-based regimen tended to have better outcome after CART or bispecific antibody treatment.

Conclusions

TP53 alterations are associated with poor outcomes in DLBCL. We identified an effective dosing schedule of selinexor (40mg QW) in combination with R-GDP/R-ICE/R-Gemox for TP53-altered refractory DLBCL patients. Further research is warranted to investigate the mechanism of action behind this treatment approach