Aleix Prat, Director of the Clínic Barcelona Comprehensive Cancer Center at Barcelona Clinical Hospital, shared a post on LinkedIn:
“What can we do for patients with HER2–negative tumors that remain after neoadjuvant chemotherapy?
Very proud to share our new study PROMETEO (SOLTI-1503), sponsored and coordinated by SOLTI cancer research, and led by Tomás Pascual Martínez and myself, now published in Nature Communications Nature Portfolio.
In early breast cancer, achieving a pathological complete response (pCR) after neoadjuvant therapy is associated with excellent outcomes.
However, tumors that do not achieve a pCR represent a high-risk scenario.
- They are associated with a substantially worse prognosis
- They remain a major unmet clinical need
Eligible patients had HER2- disease, including TNBC and HR+/HER2-, all with residual disease after neoadjuvant chemotherapy and before surgery.
PROMETEO focuses precisely on this population.
This phase II window-of-opportunity trial, conducted in the preoperative setting, explored for the first time in this context the combination of an oncolytic virus (T-VEC) with PD-L1 blockade (atezolizumab).
These studies are unique and particularly challenging to execute, requiring precise coordination within a very short time window
They depend on a strong network of committed hospitals, clinicians, surgeons, radiologists, pathologists, and research teams
The concept:
Activate the immune system directly within the tumor
What did we observe?
- 25% of patients achieved a pCR, a remarkable finding in this population
- pCR rates reached 30% in HR+/HER2-negative tumors
- We observed robust immune activation, including increased TILs, PD-L1 expression, and increased HER2DX immune/IGG expresssion after treatment
- With ~4 years of follow-up, no recurrences have been observed among patients achieving pCR
PROMETEO also reinforces the value of window-of-opportunity trials, which allow us to test new therapies and understand tumor biology in real time.
Although T-VEC will not move forward in this indication, PROMETEO provides an important proof of concept:
It is possible to induce immune activation and achieve meaningful responses in tumors with residual disease after chemotherapy.
Congratulations to the entire SOLTI cancer research network and all collaborators involved.”
Title: Talimogene laherparepvec and atezolizumab in HER2-negative breast cancer following neoadjuvant chemotherapy: a window-of-opportunity phase II trial (SOLTI-1503 PROMETEO)
Authors: Tomás Pascual, Maria Vidal, Juan M. Cejalvo, Estela Vega, Esther Sanfeliu, Guillermo Villacampa, Sergi Ganau, Ana María Julve Parreño, Esther Zamora, Ignacio Miranda, Ana Delgado, Begoña Bermejo, Elia Seguí, Fara Brasó-Maristanty, Luis de la Cruz-Merino, Manel Juan, Patricia Galván, Xavier Gonzàlez-Farré, Samyukta Chillara, Patricia Villagrasa, Adam D. Pfefferle, Constandina E. O’Connell, Juan M. Ferrero-Cafiero, Mafalda Oliveira, Charles M. Perou and Aleix Prat
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