Sotorasib 960 mg Versus Reduced Doses: Meta-Analysis of Clinical Efficacy and Toxicity

Is 960 mg Always Better in KRAS G12C Lung Cancer?

What is sotorasib, and which patients receive it?

Sotorasib is an oral small-molecule inhibitor targeting the KRAS G12C mutation. KRAS G12C is an important driver mutation, especially in lung adenocarcinoma, and can be found in approximately %13–16 of cases. Sotorasib aims to suppress tumor-growth signaling pathways such as MAPK and PI3K by trapping the KRAS G12C-mutant protein in its inactive GDP-bound form.

In the United States, sotorasib received FDA approval for patients with locally advanced or metastatic KRAS G12C-mutant non-small cell lung cancer who have received at least one prior systemic therapy. The current labeled dosing regimen is 960 mg once daily as the daily schedule.

Why is the 960 mg dose being debated?

Sotorasib's 960 mg dose has been a focus of scientific debate since the approval process. There are several reasons: absorption does not rise proportionally with dose at high doses; when increasing from 180 mg to 960 mg, blood levels do not rise as much as expected. This is called saturating absorption or saturable absorption .

In other words, taking more tablets may not always mean greater exposure to active drug. Phase 1 pharmacokinetic data reported very similar mean steady-state AUC values between doses of 180 mg and 960 mg: 31,7 mg·hour/mL versus 32,4 mg·hour/mL. Such similar systemic exposure despite a dose difference of more than fivefold raised the question: «Does a higher dose really provide more clinical benefit?»

Project Optimus: The philosophy of dose selection in oncology is changing

The sotorasib debate has become one of the best examples of the FDA's Project Optimus initiative. Traditional oncology drug development, particularly in the chemotherapy era, often sought the «maximum tolerated dose». For targeted therapies and immunotherapies, however, that approach may not always be appropriate.

With modern targeted drugs, efficacy may plateau beyond a certain dose while toxicity, loss of quality of life, treatment discontinuation and financial toxicity continue to increase. The core idea of Project Optimus, instead of the «highest tolerable dose», is the lowest effective dose with the best balance of efficacy, safety, patient adherence and quality of life to identify and select that dose.

What did the new meta-analysis investigate?

The study published in JCO Oncology Practice is an independent systematic review and meta-analysis comparing sotorasib's standard 960 mg dose with reduced starting doses. Researchers searched PubMed, EMBASE, SCOPUS, CINAHL and Web of Science through 28 October 2025 in a comprehensive search.

Initially, 12.613 records were identified. After duplicates were removed, 5.133 studies were screened; 145 full texts were examined, and finally 10 studies were included in the meta-analysis. The total number of patients was 1.477 .

Main efficacy finding: 960 mg did not appear clearly superior

In the meta-analysis, the objective response rate in patients starting at 960 mg was %33, while in patients starting at a reduced dose it was %26 . Although there was a numerical difference favoring 960 mg, it was not statistically significant. The risk ratio was 1,26 and the 95% confidence interval was 0,87–1,83 .

Nor was a significant advantage of the higher dose demonstrated for PFS. In the pooled PFS analysis, the HR was 0,77, and the 95% confidence interval was 0,56–1,05 . Thus, current data did not show that the 960 mg dose significantly improved progression-free survival compared with reduced doses.

What did the CodeBreaK dose-optimization study show?

The FDA-requested postmarketing dose-optimization study compared 960 mg with 240 mg of sotorasib. In this study, ORR in the 960 mg arm was %32,7, and in the 240 mg arm it was %24,8 . The disease control rate was 86,5% versus 81,9%, and median duration of response was reported as 13,8 versus 12,5 months in the two groups.

However, there appeared to be no significant difference in PFS or OS: PFS was 5,4 versus 5,6 months, and OS was 13,0 versus 11,7 months . Grade ≥3 treatment-emergent adverse events were more frequent in the 960 mg arm: 61,5% versus 49,0%. The study itself was not designed with sufficient power to establish definitive superiority between doses; rather than settling the dosing question, it therefore brought it into sharper focus.

Toxicity: A substantial adverse-event burden at 960 mg

In the meta-analysis, at the 960 mg dose, the rate of treatment-related adverse events of any grade was %83, and the rate of grade ≥3 treatment-related adverse events was %22 . Among patients, 17% required dose reduction, and 10% required treatment discontinuation.

The most common reasons for dose reduction or treatment discontinuation included hepatotoxicity, meaning elevated liver enzymes, diarrhea and nausea. Hepatotoxicity may be a particularly important clinical monitoring issue in patients previously treated with immune checkpoint inhibitors.

Pill burden and cost: Dose optimization is an economic issue as well as a medical one

Sotorasib's 960 mg dose means a high pill burden in practice. A daily dose of 960 mg using 120 mg tablets means 8 tablets per day . A 240 mg dose means 2 tablets per day . This difference may matter for older patients, those taking multiple medications, those with swallowing difficulties or those struggling with adverse effects.

The economic aspect was also discussed prominently in the meta-analysis. Based on wholesale acquisition costs in the United States, the 960 mg dose was estimated to cost approximately 24.000 dollarsper month, while the 240 mg dose could cost approximately 6.000 dollars . This represents a potential annual difference per patient of approximately 216.000 dollars . Over a mean treatment duration of 8,6 months, estimated savings could reach 154.800 dollars in total.

Does this study say to start at 240 mg?

No. This is the article's most important balance. The new meta-analysis shows that the 960 mg dose did not demonstrate a significant efficacy advantage over reduced doses and carries a high toxicity/cost burden. However, this does not mean that every patient should automatically start at 240 mg.

The current FDA label still specifies a 960 mg starting dose. A reduced starting dose must be assessed by a physician alongside factors such as clinical-trial data, patient frailty, liver function, previous immunotherapy, drug interactions, adverse-event risk and patient preference. The strongest need in this area is for independent prospective dose-optimization studies with sufficient statistical power.

The relationship with adagrasib: How should dosing and drug selection be considered in KRAS G12C disease?

Sotorasib is not the only option for KRAS G12C-mutant NSCLC. Adagrasib is another FDA-approved KRAS G12C inhibitor in this setting. The two drugs differ in pharmacokinetics, adverse-event profiles, drug interactions and clinical experience. For example, gastrointestinal toxicity and QTc prolongation may be prominent with adagrasib, whereas hepatotoxicity is a particular concern with sotorasib after previous immunotherapy.

The actual clinical decision is therefore not simply «How many mg of sotorasib?» The choice of KRAS G12C inhibitor should be assessed alongside the patient's comorbidities, liver function, previous treatments, brain metastasis status, drug interactions, tolerability risk and access conditions.

The right message for the patient

Message for clinical practice

This meta-analysis shows that the sotorasib dose should now be discussed not only through labeling information, but together with patient tolerability and the real-world benefit–harm balance. The absence of a significant efficacy advantage at 960 mg, alongside high toxicity, pill burden and cost, clearly demonstrates why dose optimization is so important in oncology.

The most reasonable conclusion for clinical practice is a more informed discussion of individualized dosing strategies. Starting dose and early dose modification should be assessed particularly carefully in older or frail patients, those taking multiple medicines, those with borderline liver function or those who previously experienced immunotherapy-related hepatitis/toxicity.

Conclusion

The new systematic review and meta-analysis published in JCO Oncology Practice found no significant efficacy advantage for sotorasib's labeled 960 mg dose over reduced doses in advanced KRAS G12C-mutant non-small cell lung cancer. Pooled ORR at 960 mg was %33, and at reduced doses it was %26 ; the HR for PFS was 0,77 with no statistically significant superiority.

By contrast, treatment-related adverse events were common at 960 mg: any-grade TRAE %83, grade ≥3 TRAE %22, dose reduction %17 and treatment discontinuation %10. Pharmacokinetic data also support a plateau in drug exposure across 180–960 mg and suggest that higher doses may not always produce greater biological effects.

This study does not close the question of dose optimization in sotorasib treatment; rather, it strengthens it. The most appropriate conclusion is that sotorasib is an effective KRAS G12C-targeted therapy, but dose selection in modern oncology should be just as scientific, patient-centered and value-based as drug selection.