ALX Oncology's CD47 Biomarker Data Locks In a Targeted Path Forward

Q1 update validates evorpacept in HER2+ breast cancer; biomarker-driven ASPEN-09 now the fulcrum, with a $2-4B addressable market.

ALXO · Earnings Call · 2026-05-09

What changed at ALX Oncology?

ALX Oncology reported Q1 2026 with an update that sharpens its thesis: evorpacept's CD47 target is now backed by biomarker data from two independent HER2-positive cancer studies. In the newly disclosed ESMO Breast 2026 analysis of evorpacept plus zanidatamab, patients with centrally-confirmed HER2-positive disease and high CD47 expression (≥20%) achieved a 100% objective response rate, including one complete response, with median duration of response of 20.2 months and median PFS of 22.1 months. Management framed this as “CD47 expression is a key predictive biomarker for increasing durable clinical response” — Jason Lettmann, Chief Executive Officer · 2026-05-09. Chief Medical Officer Barbara Klencke added “All five of these patients with CD47 expression responded, including one patient with a complete response.” — Barbara Klencke, Chief Medical Officer · 2026-05-09 This is a continuation, not a pivot — the company has been discussing ASPEN 09 study for several quarters. But this quarter adds an external expert voice (Dr. Sara Hurvitz) and a concrete market sizing:

We estimate that there are approximately 20,000 addressable patients who are HER2-positive and overexpress CD47, representing a $2 billion to $4 billion market opportunity in the United States, the 5 major European markets and Japan.
Barbara Klencke, Chief Medical Officer · 2026-05-09

Sara Hurvitz, a recognized breast cancer expert, called the data "pretty impressive" and noted that the real clinical need is in patients who have already progressed on ENHERTU, where median PFS is typically under 6 months. She expressed the same excitement she felt when ENHERTU data first emerged: “I feel that same flurry of excitement seeing these data because it's pretty tough to treat patients post T-DXd now.” — Sara Hurvitz, Medical Expert/Oncologist · 2026-05-09

Why it matters: biomarker-driven path

The company is structuring its Phase II breast study (ASPEN-09) around CD47 expression, with a primary endpoint of response rate in CD47-overexpressing patients. It has also upsized the trial from 80 to 120 patients to better define the optimal cut point. Recent commentary highlights the strategic shift: “It has always been a response-rate endpoint trial... I have moved that up to the primary endpoint” — Barbara Klencke, Executive · 2026-02-27 (from the February 2026 call). Earlier, Jason Lettmann confirmed the timeline: “We are guiding towards 80-patient full data from those 80 patients in mid next year.” — Jason Lettmann, Executive · 2026-02-27 This biomarker approach is intended to de-risk a future Phase III. However, management is cautious about the regulatory path; as Klencke said this quarter: “Our base case is that a Phase III trial will be required because the bar is high for accelerated approval” — Barbara Klencke, Chief Medical Officer · 2026-05-09. That is a meaningful nuance — despite the striking ORR data, the company is not assuming an accelerated approval path. The Fc domain engineering of evorpacept remains a differentiator, avoiding on-target toxicities that killed prior CD47 inhibitors. The safety database is now more than 800 patients, and the mechanism—blocking the "don't eat me" signal without engaging an active Fc—now has consistent clinical data across breast and gastric HER2-positive cancers, supporting the ESMO Breast data and the broader pipeline. Meanwhile, the company's second asset, ALX2004, an EGFR-targeted ADC, is progressing through dose escalation and is on track for an initial safety readout in the second half of 2026. Management emphasizes that both programs could be ready for registrational studies by end of next year.

Financial and tape context

ALX ended Q1 with a strengthened balance sheet. Effective net cash rose to $293M, up 54% year-over-year, and cash runway jumped to 7.5 quarters from 2.4 in Q4 2025. R&D spend is down 43% year-over-year, reflecting disciplined execution. The stock has been in a chronic drawdown from its December 2020 peak of $112.26 — down 98.2% — though over the last 90 days it has risen about 20%, a small recovery from a low base. Market cap is under $300M, so each clinical catalyst can move shares significantly. The broader market's top themes this quarter are dominated by data centers and tariffs, but ALX's story is company-specific and clinical. Several large pharma and biotech reporters this week also discussed emerging biotechs and accelerated approval themes, but none with ALX's exact mechanism. This remains a one-of-a-kind name in a challenging small-cap biotech environment, and today's data adds another layer of evidence to the CD47 expression biomarker narrative that has been the company's core investment thesis.