Hematopoietic Stem Cell Transplant in Novel Agent Era Is Associated with Improved Survival in Relapsed and Refractory Peripheral T-Cell Lymphoma

Background

Conventional salvage chemotherapy has limited efficacy in relapsed or refractory (R/R) peripheral T-cell lymphoma (PTCL). In the last decade, several novel agents, including pralatrexate, an antifolate, brentuximab vedotin (BV), a CD30-directed antibody-drug conjugate, and romidepsin, a histone deacetylase inhibitor, have been introduced into clinical practice based on phase 2 data demonstrating efficacy in relapsed/refractory (R/R) diseases. Their impact on real world survival remains to be defined. In this single-center retrospective cohort study we assessed survival including outcomes after hematopoietic stem cell transplant (HSCT) with respect to novel agent exposure.

Methods

Patients diagnosed with PTCL from 2012-2017 who consented for inclusion in the Weill Cornell lymphoma and bone marrow transplant databases with adequate treatment records were included. Medical records were reviewed for baseline characteristics, treatment course, and outcomes including overall survival and HSCT. Median follow-up time was estimated on overall survival by reverse Kaplan-Meier method. Overall Survival (OS) time was calculated from date of diagnosis to date of death or last follow-up. Kaplan-Meier estimator was used to estimate survival probability. Survival difference between groups was tested by log-rank test and Cox regression analysis for statistical significance.

Results

A total of 123 cases were reviewed with median follow-up of 34 months. The major PTCL subtypes were PTCL NOS (N=34, 27.6%), angioimmunoblastic T-cell lymphoma (N=21, 17%), adult T-cell leukemia/lymphoma (N=19, 15.4%), and anaplastic large cell lymphoma (N=14, 11.4%). The most common 1^st line chemotherapy regimens were CHOP (N=34, 31.5%), EPOCH (N=21, 19.4%), or CHOEP (N=10, 9.3%). Ninety-two patients had relapsed or refractory disease, and the most common 2^nd line therapies were DICE/ICE (N=17, 18.4%), gemcitabine-based regimens (N=6, 7.5%), bendamustine (N=5, 5.4%), hyperCVAD (N=5, 5.4%), or combinations of novel agents. Thirty-three R/R patients received a novel agent, including pralatrexate alone (N=3), BV (N=13), or romidepsin (N=17). Thirty-six R/R patients underwent HSCT, including 26 allogeneic and 10 autologous.

Baseline characteristics at diagnosis including age, gender, Ann Arbor stage, ECOG status, and IPI were similar between R/R patients who received a novel agent and those who did not. Although no differences in OS were seen with novel agent use among patients with R/R disease, there was a significant difference in OS among patients who received HSCT and those who did not (p=0.012 by log-rank test). Compared to no HSCT, significantly improved survival was observed in patients receiving allogeneic HSCT (HR = 0.47, p = 0.03) as well as autologous HSCT (HR = 0.27, p= 0.03) by Cox regression survival analysis, both univariate and multivariate when adjusting for interaction with novel agents.

Conclusion

Data from this single-center retrospective cohort study suggest that hematopoietic stem cell transplant, both autologous and allogeneic, was associated with overall survival benefit in R/R diseases in the novel agent era. The real world impact of novel agents use in PTCL subtypes warrants further study, preferably in a prospectively designed multicenter population study with larger sample size where disease subtypes, therapeutic targets of novel agents, and line of therapies can be sufficiently delineated for response and survival analysis.