SABCS 2025 – pumitamig replicates breast cancer findings

BioNTech and Bristol Myers Squibb’s PD-L1 x VEGF project pumitamig looked good in a Chinese trial in triple-negative breast cancer last year, and now it’s produced similar results in a global mid-stage study.

While there are some differences between the trials, one notable finding in both was a similar performance across patients regardless of PD-L1 status. However, in the recently begun global phase 3 Rosetta Breast-01 study the groups are homing in on patients with PD-L1 expression below 10% – thereby avoiding Merck & Co’s Keytruda, which as part of a chemo combo has a US green light only in 10% or higher expressers.

Global phase 2 

The latest results, being presented in a poster at the San Antonio Breast Cancer Symposium, come from the global phase 2 BNT327-02 trial, which enrolled first as well as second-line TNBC patients. It tested pumitamig at two different doses plus various chemotherapies.

In cohort one, which combined pumitamig at 15mg/kg or 20mg/kg every two weeks with Abraxane, the confirmed overall response rate was 62%. Including unconfirmed responses bumped that number up to 72%.

Cutting the data by PD-L1 expression led to an identical confirmed and unconfirmed response rate, 71%, in ≥10% and <10% expressers.

Response rates were better with the 20mg/kg dose (80%) versus 15mg/kg (63%), and were also better in first-line (76%) versus second-line patients (68%, all confirmed plus unconfirmed).

The numbers look similar to those seen last year at ESMO and SABCS from a phase 1/2 Chinese trial, especially taking into account that this was in first-line TNBC only. That study reported a confirmed ORR of 74% among 42 patients. Cutting by PD-L1 status found ORRs of 77% in <1%, 56% at 1-10%, and 100% at ≥10% expression.

In the Chinese study, median progression-free survival was 13.5 months, while median overall survival wasn’t reached. In the global trial these endpoint were still immature.

The latest data seem to bode well for Rosetta Breast-01, which began in October, in first-line TNBC patients with PD-L1 expression of 10% or lower. That study will compare pumitamig plus physician’s choice of chemo, versus chemo alone, with co-primary endpoints of PFS and OS. Pumitamig will be dosed at 1,500mg every two weeks, or 2,000mg every three weeks, equivalent to the 20mg/kg dose tested in phase 2.

Still, it’s notable that BioNTech and Bristol aren’t pitting their project, which was originated by Biotheus, against Keytruda in higher expressers.

Data with pumitamig + chemo in TNBC

Notes: *data from cohort 1: pumitamig (15mg/kg or 20mg/kg Q2W) + Abraxane; across cohorts 1 & 2 (cohort 2: pumitamig 20mg/kg + paclitaxel, gemcitabine + carboplatin, or Halaven); ^no pumitamig-related deaths but one paclitaxel-related death. Source: SABCS & company releases.