On April 25, 2025 ALX Oncology Holdings Inc., ("ALX Oncology" or the "Company") (Nasdaq: ALXO), a clinical-stage biotechnology company advancing a pipeline of novel therapies designed to treat cancer and extend patients’ lives, reported encouraging data from an ongoing Phase 1/2 investigator-sponsored trial (IST) of the company’s lead clinical candidate, evorpacept, in combination with standard-of-care rituximab and lenalidomide (R2) in patients with indolent and aggressive relapsed or refractory B-cell non-Hodgkin lymphoma (R/R B-NHL) (Press release, ALX Oncology, APR 25, 2025, View Source [SID1234652136]). Final results from the Phase 1 portion of the trial will be presented Tuesday, April 29, during a poster presentation at the American Association for Cancer Research (AACR) (Free AACR Whitepaper) (AACR) Annual Meeting 2025 in Chicago, Illinois.

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"In patients with indolent B-NHL, increases in certain pro-tumoral macrophages can promote resistance to important frontline standard-of-care treatments, including R2," said Paolo Strati, M.D., the trial’s lead investigator and Associate Professor of Lymphoma-Myeloma at The University of Texas MD Anderson Cancer Center. "Evorpacept is uniquely designed to activate the innate immune system and engage macrophages to enhance the therapeutic benefits of and deepen responses to anti-cancer antibodies such as rituximab. This trial suggests evorpacept has a synergistic effect with R2 that may help improve outcomes and overcome resistance to R2 in this patient population."

The clinical trial conducted by Dr. Strati and colleagues at MD Anderson enrolled a total of 20 patients with indolent (n=18) and aggressive (n=2) R/R B-NHL; all 20 had previously received an anti-CD20 monoclonal antibody (rituximab), 72% had received prior chemoimmunotherapy and 80% had progressed within 24 months from frontline therapy. Patients with indolent NHL had received at least one prior line of systemic therapy. Investigators administered the CD47-blocker evorpacept at two dose levels: 30 mg/kg Q2W (n=3) or 60 mg/kg Q4W (n=17) in combination with standard R2 treatment. The regimen was well- tolerated, and there were no dose-limiting toxicities.

After a median follow-up of 28 months (95% CI, 18-28 months) the two-year progression-free survival (PFS) rate was 69% and two-year overall survival (OS) rate was 84%. Sixteen patients (80%) achieved complete responses and the best overall response rate (ORR) was 90%. As previously reported at the AACR (Free AACR Whitepaper) 2024 Annual Meeting, the CR rate among the 18 patients with iNHL was 83%. This complete response rate achieved by evorpacept + R2 in this trial compares favorably to the 34% historical CR rate for R2 alone. During treatment, a significant increase in T cells and anti-tumoral macrophages was observed.

"The final results from this Phase 1 study reinforce evorpacept’s potential to meaningfully deepen and enhance responses to many of the most important cancer therapies available today, including anti-cancer antibodies such as rituximab, and to thereby help address significant, unmet needs in cancer treatment," said Jason Lettmann, Chief Executive Officer of ALX Oncology. "We look forward to the continued evaluation of evorpacept in patients with previously untreated and high tumor-burden indolent NHL in the Phase 2 portion of this study."

The Phase 2 portion of this IST in patients with previously untreated iNHL is ongoing and has completed enrollment.

Details of the poster to be presented at AACR (Free AACR Whitepaper) 2025 are as follows:

Title: Final results of a phase I trial of evorpacept (ALX148), lenalidomide, and rituximab for patients with B-cell non-Hodgkin lymphoma
Presenter: Paolo Strati, M.D., Associate Professor of Lymphoma-Myeloma, The University of Texas MD Anderson Cancer Center
Session Title: Late-Breaking Research: Clinical Research 3
Date/Time: Tuesday, April 29, 2025, from 2:00 p.m. – 5:00 p.m. CT
Location: McCormick Place Convention Center, Poster Section 53
Poster Board Number: 13
Published Abstract Number: LB369

A copy of the AACR (Free AACR Whitepaper) 2025 IST presentation will be available in the "Publications" section of the ALX Oncology website following the presentation.