Treatment of Peripheral T-Cell Lymphoma: Many Shades of Gray

Previously obscured within other designations of aggressive lymphomas, peripheral T-cell lymphoma (PTCL) now represents 23 different subtypes of non-Hodgkin lymphoma (NHL). Despite the many subtypes now recognized, PTCL represents only approximately 10% of all NHL cases diagnosed. Positron emission tomography/computed tomography has become essential to accurate staging and response-evaluation for PTCL. In comparison to aggressive B-cell NHL, patients with PTCL will more often be refractory to initial therapy, and chemosensitive patients will have shorter disease-free periods. Anthracycline-based regimens, often with the inclusion of etoposide, are commonly used during induction therapy. Consolidation with high-dose therapy and autologous stem cell transplantation (ASCT) in first chemosensitive remission appears to provide the best outcome in common nodal PTCL subtypes. The commonly defined nodal subtypes are PTCL not otherwise specified, angioimmunoblastic T-cell lymphoma, and anaplastic lymphoma kinase (ALK)-positive or ALK-negative anaplastic large-cell lymphoma (ALCL). Four agents have been approved by the US Food and Drug Administration for use in the relapsed/refractory (rel/ref) setting, including belinostat (2014), romidepsin (2011), brentuximab vedotin (2011), and pralatrexate (2009). Brentuximab vedotin was approved only for the ALCL subtype. These agents continue to be studied as combinations in the rel/ref setting and as additions or substitutions for other agents in upfront multiagent chemotherapy regimens. Patients who have responded to treatment in the rel/ref setting and are considered transplant-eligible should be considered for allogeneic stem cell transplantation, especially those with previous ASCT. Upfront allogeneic stem cell transplantation remains a research question in the majority of PTCL subtypes, but data are emerging.