CHOSA and AIDA present data at ASCO 2026 showing up to 78% pathological complete response (pCR) rate in breast cancer using combined, integrated, taxane and platinum biomarkers

The English text is an unofficial translation. In case of any discrepancies between the Swedish text and the English translation, the Swedish text shall prevail.

01 June 2026 - CHOSA Oncology AB (“CHOSA” or the “Company”) in cooperation with and AIDA Oncology ApS (“AIDA”) today jointly announces publication of a new ASCO 2026 abstract presenting data from the I-SPY2 study showing that combined use of CHOSA’s platinum Drug Response Predictor - Platin-DRP® from CHOSA - and a taxane docetaxel response predictor Oncotect from AIDA, through a collaboration with AIDA Oncology, identified breast cancer patient subgroups with markedly higher response rates to neoadjuvant chemotherapy in breast cancer. The combined, integrated prediction of platin and taxane response was jointly developed between CHOSA and AIDA.

Background: Triple-negative breast cancer (TNBC) accounts for approximately 15–20% of all breast cancer cases and remains one of the most aggressive breast cancer subtypes, with a substantial risk of recurrence despite advances in treatment. Taxanes (paclitaxel and docetaxel) and platinum agents, particularly carboplatin, are among the most important components of modern neoadjuvant treatment regimens for TNBC.

Achieving optimal outcomes depends on selecting therapies to which an individual patient's tumour is sensitive. CHOSA’s Platin-DRP® and AIDA’s Oncotect® taxane predictor have previously demonstrated the ability to predict response to platinum- and taxane-based therapies, respectively. As both drug classes form a cornerstone of current TNBC treatment, we evaluated whether combining these two drug-specific biomarkers could further improve the identification of patients most likely to achieve a pathologic complete response (pCR) and benefit from intensified neoadjuvant treatment.

The abstract has additionally been selected for poster presentation at the American Society of Clinical Oncology - ASCO - Annual Meeting 2026 in Chicago.

The study analyzed patients from the I-SPY2 trial receiving neoadjuvant veliparib-carboplatin in combination with standard taxane-anthracycline chemotherapy (VC arm). Results demonstrated that combining drug-specific gene expression predictors may significantly improve identification of patients most likely to achieve pathologic complete response (pCR).

Key findings from the abstract include:

• Patients classified as high for both platinum and taxane response signatures achieved a pCR rate of 78% (7/9 patients)

• Patients classified as low for both biomarkers had a pCR rate of 0% (0/8 patients)

• Double-high patients showed a pCR rate of 55% versus only 19% in double-low patients

• The overall pCR rate in the veliparib-carboplatin treatment arm was 38%, compared with 17.3% in the control arm

• CHOSA’s Platin-DRP® independently predicted pCR with an odds ratio (OR) of 3.4 (p = 0.016)

• The taxane Oncotect® predictor from AIDA independently predicted pCR with an OR of 3.88 (p = 0.01).

Importantly, both predictors retained independent predictive value after adjustment for established risk classification by MammaPrint.

The data suggest that combining drug-specific biomarkers may enable more precise selection of patients likely to benefit from platinum addition to taxane-based neoadjuvant chemotherapy regimens. Likewise, data show that those who had a score of 0% had no benefit – and a hence an alternative treatment approach should be considered, and unnecessary side effects can be avoided.

“Achieving pathologic complete response is strongly associated with improved long-term outcomes in early breast cancer. We believe these data represent an important step toward more individualized chemotherapy selection using combined biomarkers for the most widely used cancer drug classes,” said Peter Buhl Jensen, CEO of CHOSA.

Abstract title:

“Taxane and platinum combination as a predictor of pathologic complete response in I-SPY2 by gene expression breast cancer signatures”

The poster presentation details are:

Abstract number: 544048
Poster Session: Breast Cancer - Local/Regional/Adjuvant
Poster board number: 93
Presentation date/time: June 1, 2026, 1:30 PM–4:30 PM CT

The abstract is publicly available via ASCO’s website:
https://www.asco.org/abstracts-presentations/265828

The poster is attached.

This information is information that CHOSA Oncology AB is obliged to make public pursuant to the EU Market Abuse Regulation (MAR). The information was submitted for publication, through the agency of the contact person set out above, at 20.30 CET on 1 june.

  

For more information please contact:

Peter Buhl Jensen, CEO

peter@chosa.bio

+ 45 21 60 89 22

 

About the study
The analysis included gene expression data from 987 high-risk early breast cancer tumors from the I-SPY2 trial, including 71 patients treated with veliparib-carboplatin plus standard chemotherapy and 179 HER2-negative control patients treated with standard taxane-anthracycline chemotherapy alone.

About CHOSA Oncology AB
CHOSA Oncology is a precision oncology company developing Platin-DRP®, a gene expression–based biomarker that predicts response to platinum-based chemotherapy. By identifying patients most likely to benefit, CHOSA aims to improve outcomes and optimize treatment selection in cancer care.

About AIDA Oncology ApS

AIDA Oncology is a precision oncology company based in Denmark and the UK that focuses on improving cure rates in early breast cancer treatment outcomes by enabling clinicians to match individual patients with the drugs most likely to work for them. AIDA’s highly scalable, software-only platform applies AI-derived algorithms to the gene expression patterns of patient tumours to predict drug efficacy across the five most widely used drug classes in breast cancer, an approach validated in approximately 2,800 patients to date.  Beyond better patient outcomes, AIDA’s approach delivers significant savings for hospital systems by reducing wasted drug spend and avoidable side-effects. Backed by the BioInnovation Institute (BII) and Denmark’s Export and Investment Fund (EIFO), AIDA is led by a proven expert Oncology team.

Background

Cisplatin and its sister molecule carboplatin have been cornerstones in lung cancer therapy for decades. Despite advances in immunotherapy, platinum drugs remain critical in treatment regimens, including combinations with PD-1/L1 inhibitors. While numerous efforts to predict cisplatin efficacy have failed, the Platin-DRP, based on a 205-gene biomarker signature, has shown promising results in other settings, including adjuvant therapy in NSCLC and progression-free survival in breast cancer.

As previously announced, CHOSA is also exploring the predictive potential of Platin-DRP in those treated with carboplatin in lung cancer. Data from the SPLENDOUR trial provides a unique opportunity to validate this tool in a large cohort and potentially confirm its utility across both drugs. Future research will also aim to determine whether Platin-DRP can predict the effectiveness of platinum drugs combined with PD-1/L1 inhibitors. CHOSA Oncology AB is an oncology biotechnology company led by an experienced international team with expertise in oncology, drug development, clinical trials, regulatory affairs, and business development. CHOSA intends to enter into partnership or sublicensing agreements for LiPlaCis® and the DRP®.

About Platin-DRP, a test to predict if cisplatin treatment is likely to be successful

CHOSA is focused on its Platin-DRP® drug response predictor, to which it holds worldwide rights. Platin-DRP is a validated test designed to help identify patients most likely to benefit from cis- and carboplatin treatment. Breast: Strong phase 2b data in metastatic breast cancer have shown that patients selected by DRP® responded better to treatment, had longer progression-free survival, and may also have achieved longer overall survival than patients identified as unlikely to respond well. Lung: Platin-DRP has also demonstrated its ability to predict the benefit of adjuvant cisplatin in lung cancer. Cisplatin treatment after surgery remains a gold standard that can improve cure rates, but doctors have not had a validated tool to identify which patients are most likely to benefit. This is where Platin-DRP may become a game changer, particularly in newer neoadjuvant settings where immunotherapy has shown high efficacy in combination with platinum doublets. Platin-DRP was validated in a blinded retrospective study in two lung cancer patient cohorts receiving cisplatin after surgery to eliminate residual tumour cells. Patients with the 10% highest scores had a 3-year survival of 90%, whereas patients with the lowest 10% scores had a 3-year survival of only 40%¹. In 2026 CHOSA in collaboration with key opinion leaders in lung cancer showed the Platin-DRP in advanced clearly separated the patient with a sensitive cancer from a platin resistant tumor with a median survival of 16.9 months in the former group vs only 5.5 months in the latter2.  

Immunotherapy Cisplatin and carboplatin have often been shown to activate the immune system, potentially making “cold” tumours more susceptible to PD-1 inhibitors. This synergy may be important not only in lung cancer, but also in breast cancer, bladder cancer and head & neck cancer. In the growing PD-1 inhibitor market, CHOSA’s approach may offer the ability to predict whether platin can provide synergy with PD-1 inhibition, potentially creating a meaningful advantage for treatment selection and future partners.

 

1) Buhl et al PLOS One doi: 10.1371/journal.pone0194609 2) ESMO Open Volume 11, Supplement 3, 106773, April 2026

DRP® is a registered trademark of Allarity Therapeutics, Inc., and is used under license granted to CHOSA. LiPlaCis is in-licensed from Allarity Therapeutics Ltd (previous Oncology Venture ApS) and LiPlasome Pharma ApS.

 

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