In recent years, immunotherapy has often been communicated simply as PD-L1 inhibitor + chemotherapy, creating the perception that chemotherapy could eventually be phased out. However, the 2025 treatment overview presented by Jarushka Naidoo (MD BCH MHS) and a comprehensive Frontiers in Oncology meta-analysis* underline that platinum combinations remain indispensable in achieving survival benefit. The analysis shows that platinum-based chemotherapy and PD-1/PD-L1 inhibition represent equally important and interdependent therapeutic partners.

Across eight market leading PD-1/PD-L1 inhibitors - nivolumab, pembrolizumab, atezolizumab, cemiplimab, durvalumab, sintilimab, tislelizumab, and toripalimab - overall survival and progression free survival significantly improved when combined with cisplatin or carboplatin.

"These findings remind us that while immunotherapy has revolutionized lung cancer care, its success is built on platinum chemotherapy," said Peter Buhl Jesen, MD, DMSc, CEO of CHOSA Oncology. "Cisplatin and carboplatin are not being replaced - by Chosa’s Platin-DRP® technology they are being redefined as precision-enabled partners in modern oncology."

This insight also extends to the next generation of combination regimens, including bispecific antibodies and dual-checkpoint (PD-1 + CTLA-4) approaches, where platinum-based chemotherapy continues to serve as the immunologic primer for tumor response.

The test, based on a 205-gene Platin-DRP® signature, has previously been validated for cisplatin in two independent, blinded lung cancer clinical trial datasets and in a prospective phase 2 breast cancer study. In a recent collaboration with ETOP/EORTC the Platin-DRP® was independently validated and showed prediction of survival for lung cancer patients treated with cisplatin as well as carboplatin. The same predictor was evaluated in a cohort of 20 breast cancer patients treated with carboplatin, to assess whether a cisplatin-derived signature could predict response to its sister compound. The results were statistically significant and supportive - forming the basis of CHOSA’s Poster presentation at the annual ESMO conference.

For additional information, contact:

Peter Buhl Jensen, CEO
Peter@chosa.bio  
+ 45 21 60 89 22

Background

Cisplatin and its sister molecule carboplatin have been cornerstones in lung cancer chemotherapy 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 Cisplatin-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 the Cisplatin-DRP not only in cisplatin-treated patients but also 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, potentially confirming its utility across both drugs. Future research will aim to determine whether the Cisplatin-DRP can predict the effectiveness of combinations of platinum drugs with PD-1/L1 inhibitors.

CHOSA in short

CHOSA Oncology AB is an oncology biotechnology company led by a proven international team with veteran specialists in oncology; drug development; running clinical trials; regulatory expertise; and business development. CHOSA intends to enter into agreements for partnership or sublicensing of LiPlaCis® and the DRP®.

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

CHOSA is focused on late-stage clinical development of LiPlaCis® and its DRP® drug response predictor to which it has worldwide rights. The cisplatin DRP is the only proven test to foresee and thereby select who to treat and who will benefit from cisplatin. Breast: We have strong phase 2b data in metastatic breast cancer, demonstrating that patients selected by DRP® responded better to treatment; have longer progression-free survival; and maybe even an overall longer total survival than those patients who were identified as unlikely to respond well to the treatment.

Lung: The cisplatin DRP has previously shown its ability to foresee the value of cisplatin therapy in lung cancer. Cisplatin therapy after surgery is a gold standard that increases lung cancer cure, but not always, and until now the doctors do not know who will benefit from cisplatin and who should have something else. This is where the cisplatin DRP is a potential game changer, especially in new neoadjuvant treatment where immunotherapy obtains high efficacy rates when combined with cisplatin doubles. Cisplatin DRP was validated in a blinded retrospective study in two lung cancer patient cohorts receiving cisplatin after surgery to kill remaining tumor cells. Thus, patients with the 10% highest scores had a 3-year survival of 90% whereas the patients with the lowest 10% score had much lower survival with only 40% surviving 3 years1.

Immunotherapy There is a new development that adds further value to our DRP. Cisplatin has often been shown to activate the immune system (making cold tumors hot), which makes tumors susceptible to PD1 inhibitors. This synergy is particularly important but not limited to the treatment of lung cancer, bladder cancer, and head and neck cancer. In the ever-growing PD1 inhibitor market, where competition is fierce, our company stands out with the ability to predict if cisplatin will provide synergy with PD1. This can give the PD1 selling companies a significant competitive advantage.

1) Buhl et al PLOS One doi: 10.1371/journal.pone0194609

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.