The Phase 3 OptiTROP-Lung05 trial, conducted in China and led by Kelun-Biotech, demonstrated a 65% reduction in the risk of tumor progression when sacituzumab tirumotecan (sac-TMT, also known as SKB264/MK-2870) was combined with Merck’s KEYTRUDA (pembrolizumab), compared with KEYTRUDA alone in previously untreated patients with PD-L1-positive advanced non-small cell lung cancer (NSCLC). Kelun-Biotech announced the top-line results on Nov. 24, 2025, stating that the study met its primary endpoint of progression-free survival (PFS) with a statistically significant and clinically meaningful benefit.

According to Kelun’s press release, the combination therapy showed a positive trend in overall survival (OS), although the data remain preliminary and require longer follow-up for confirmation.

Multiple reports, including those from STAT and BioPharma Dive, noted the early survival benefit favoring sac-TMT but emphasized that the OS data are not yet mature. The topline announcements did not include detailed OS hazard ratios or median survival figures.

The trial enrolled patients with PD-L1 expression of 1% or higher and compared the sac-TMT plus KEYTRUDA regimen to KEYTRUDA monotherapy. Kelun’s newsroom highlighted that in a separate sac-TMT lung cancer study involving chemotherapy, median PFS was 8.3 months versus 4.1 months, with a hazard ratio of 0.35, underscoring the drug’s broader efficacy in lung cancer. Subgroup analyses reported by Kelun showed hazard ratios of 0.39 for HER2-zero and 0.31 for HER2-low patients, although these findings were not specific to the OptiTROP-Lung05 trial. An objective response rate (ORR) of 41.5% versus 24.1% was also cited in a separate lung cancer dataset posted by Kelun.

The OptiTROP-Lung05 trial is the first Phase 3 study to demonstrate the successful combination of an antibody-drug conjugate (ADC) targeting TROP2 with a PD-1 immune checkpoint inhibitor in the first-line treatment of advanced NSCLC, according to Kelun. The company described sac-TMT as a TROP2-directed ADC and views the data as supporting a potential new first-line treatment option for a subset of NSCLC patients. Merck, which partnered with Kelun-Biotech on the drug’s development, reiterated these findings in its ASCO 2026 materials, where the study was presented in the metastatic lung cancer oral abstract session.

Safety data from the trial were consistent with prior testing of sac-TMT, though detailed adverse event information was not included in the publicly available reports. Merck’s ASCO 2026 release noted ongoing global Phase 3 studies evaluating sac-TMT both in combination with pembrolizumab and as monotherapy. Kelun confirmed plans to engage with Chinese regulatory authorities to discuss potential approval filings based on the OptiTROP-Lung05 results.

The development of sac-TMT remains in late-stage clinical testing, with the OptiTROP-Lung05 findings serving as an important proof of concept for the Merck-Kelun collaboration in advancing ADC and immune checkpoint inhibitor combinations earlier in lung cancer treatment. The companies continue to explore the drug’s potential across multiple studies worldwide.

The drug’s activity was observed in early-stage clinical trial data where nearly half of pancreatic cancer patients treated with the pill alone experienced tumor shrinkage or disappearance. Additionally, 71% of these patients avoided disease progression at six months, according to trial results disclosed by Erasca.

Erasca’s pan-RAS inhibitor demonstrated a 40% unconfirmed overall response rate in patients with KRAS G12X-mutated pancreatic cancer receiving second-line treatment, company officials said.

In patients with advanced non-small cell lung cancer (NSCLC), the experimental pill showed an even higher tumor response rate of 62%, officials said. The drug targets multiple RAS gene variants, mutations that are known drivers of some of the deadliest cancers, including pancreatic and lung cancers. Erasca’s clinical trial data, presented in spring 2026, positions the pan-RAS inhibitor as a novel approach to treating KRAS-driven malignancies across multiple cancer types, sources confirmed.

The response rates reported by Erasca represent a significant improvement over traditional chemotherapy, where tumor shrinkage typically ranges between 23% and 43% for pancreatic cancer, according to company statements. The drug also demonstrated a more favorable safety profile, with fewer side effects compared to conventional chemotherapy. Company officials highlighted that patients experienced better tolerance to the pill, which contrasts with adverse effects reported with some competing RAS inhibitors, including skin rashes and other toxicities documented by former Senator Ben Sasse, who underwent treatment with a different RAS-targeting drug.

Erasca’s pan-RAS pill is competing in a rapidly evolving field alongside Revolution Medicines’ daraxonrasib, which recently showed promising results in metastatic pancreatic cancer. Daraxonrasib, when combined with chemotherapy, achieved a 58% tumor response rate and 84% progression-free survival at six months, according to data released by Revolution Medicines. In comparison, Erasca’s monotherapy approach yielded a 40% response rate and 71% progression-free survival at the same time point. Both companies are pursuing different clinical strategies within the RAS-targeting space, sources said.

Revolution Medicines’ daraxonrasib has also received FDA breakthrough therapy designation and was accepted into the agency’s national priority voucher pilot program, accelerating its regulatory pathway, records show. Erasca’s data, while promising, currently represent early-phase results that require validation in larger, randomized controlled trials, officials noted. Both companies are advancing their pipelines amid increasing competition and regulatory scrutiny in the RAS inhibitor market.

Erasca’s clinical trials enrolled patients with KRAS G12X mutations in the second-line treatment setting for pancreatic cancer, including both monotherapy and combination treatment cohorts. The lung cancer trials included patients with advanced non-small cell lung cancer harboring KRAS mutations, with sufficient enrollment to demonstrate tumor response rates across these indications, according to trial protocols. The trial designs benchmarked results against established chemotherapy efficacy to assess comparative benefits.

The companies’ announcements in spring 2026 underscore the growing momentum in developing targeted therapies for KRAS-driven cancers, a historically difficult area in oncology. Both Erasca and Revolution Medicines are planning further clinical studies to extend and confirm early efficacy findings. Future research will focus on larger patient populations and direct comparisons between RAS inhibitors and chemotherapy, sources said.

Validation of these drugs’ clinical benefits depends on successful progression through ongoing and upcoming trials, with the potential to expedite market access if regulatory agencies grant accelerated approvals. The evolving landscape of RAS-targeting therapies reflects a critical advance in addressing mutations that contribute to high mortality rates in pancreatic and lung cancers, officials added.