Stem Cell Transplant (SCT) and Pralatrexate Therapy: Outcome of Patients with Relapsed or Refractory Peripheral T-Cell Lymphoma Who Received SCT Prior to or Following Pralatrexate Therapy.
Authors: Popplewell Leslie , Pro Barbara , Jacobsen Eric , Horwitz Steven M. , Boyd Adam , Patterson Molly , Fruchtman Steven , O'Connor Owen A 
Published: October 2019

Abstract
Abstract 3420
Poster Board III-308

Background
Stem cell transplant (SCT) may be offered as a curative approach in patients with chemotherapy-sensitive peripheral T-cell lymphoma (PTCL). Thus, new agents with the ability to induce a response for relapsed or refractory patients are important to identify. This analysis evaluated SCT use before or after pralatrexate, a new anti-folate, as monotherapy in the PROPEL study.

Methods
Patients with relapsed or refractory PTCL received pralatrexate 30 mg/m2 by IV push once weekly for 6 weeks in 7-week cycles with vitamin B12 and folic acid supplementation in PROPEL. Eligibility criteria included histologic confirmation of PTCL by central review, disease progression after ≥ 1 prior treatment, and ECOG performance status £ 2. Response was assessed centrally using the International Workshop Criteria. Patients who had received prior allogeneic SCT were not permitted to enroll. Patients with prior autologous SCT were eligible if they had not relapsed within 75 days of SCT. There were no restrictions on SCT after completing study treatment. Subsequent post-pralatrexate therapies were recorded during follow up until patient death, loss to follow-up, or data cutoff.

Results
One-hundred and nine patients in the PROPEL trial were evaluable for response. Eighteen (16%) had received autologous SCT previously, including 8 (7%) patients for whom SCT was the most recent therapy prior to study enrollment. The overall response rate (ORR: complete response [CR/CRu] or partial response [PR]) was 33% (6/18), including 2 CRs, for patients with a prior autologous SCT at any time prior to receiving pralatrexate and 63% (5/8), including 2 CRs, for those patients whose most recent therapy was autologous SCT. Patients were followed from initiation of pralatrexate for a median of 10.5 months (range, 1.0-24.0). Of the 109 patients who were evaluable for response, 6 (6%) patients went on to SCT (2 autologous SCT, 4 allogeneic SCT) as their initial subsequent therapy after responding to pralatrexate according to investigator assessment of response. Four of these patients were still in response by central review at the time they started SCT. At the time of data cutoff, no additional therapy was administered to any of these 4 patients post SCT. The other 2 patients had PRs by investigator review and progressive disease by central review at the time SCT was started; neither of these patients had additional therapy documented after SCT. All 6 patients were alive at the time of last contact.

Conclusions
The PROPEL trial showed that pralatrexate as a single agent had activity, including CRs, in patients who relapsed following an autologous SCT. The PROPEL trial also demonstrated that patients with relapsed or refractory PTCL can proceed to subsequent SCT after achieving a response with pralatrexate, permitting these patients a transplant option and potential cure.

Disclosures
Pro: Allos Therapeutics, Inc.: Research Funding. Jacobsen:Allos Therapeutics, Inc.: Consultancy. Horwitz:Allos Therapeutics, Inc: Consultancy, Research Funding. Boyd:Allos Therapeutics, Inc.: Employment. Fruchtman:Allos Therapeutics, Inc.: Employment.