Early BMI Change and Immuno Lung Cancer #AACR26

KRAS HUB: Help Understand Better

Early BMI Change and Immunotherapy Response in Advanced NSCLC

📍Full peer reviewed paper is still to come.

Summary

A small increase in BMI during the first 3 to 4 weeks of treatment was linked with better outcomes in advanced NSCLC treated with immunotherapy, especially immunotherapy plus chemotherapy.

This is an early clinical clue, not a promise for any one person.

For people with a KRAS mutation, the abstract is especially interesting because KRAS alterations were more common in the higher BMI group, which suggests a possible connection between metabolism, body state, and treatment response.

Knowledge

• This study looked at 1,110 people with advanced NSCLC treated with ICI alone or ICI plus chemotherapy. Researchers tracked BMI at baseline and again at 3, 6, and 9 weeks.

• The strongest signal appeared at 3 weeks. In the chemo immunotherapy group, each 1 percent increase in BMI at 3 weeks was associated with a higher chance of response and longer progression free and overall survival.

• The practical meaning is simple. If weight holds steady or rises a little early in treatment, that can be an encouraging sign. If weight falls early, that can be a signal to check symptoms, nutrition, hydration, inflammation, and treatment tolerance quickly.

ICI means immune checkpoint inhibitor. This is a type of cancer treatment that helps the immune system recognize and attack cancer cells.

• BMI means body mass index. This is a measure based on height and weight that helps track body size over time.

• NSCLC means non small cell lung cancer. This is the most common type of lung cancer.

• Chemo immunotherapy means chemotherapy and immunotherapy given together.

• ORR means objective response rate. This shows how many people see their cancer shrink with treatment.

• PFS means progression free survival. This is the length of time the cancer stays under control.

• OS means overall survival. This is the length of time people live after starting treatment.

Research

• This was a retrospective study, which means it shows association and predictive value. It does not prove that gaining weight causes treatment to work better.

• Researchers also looked at circulating proteins and tumor genomic alterations. In the higher BMI group, mutations in KRAS, KMT2A, RASA1, FANCA, CTNNB1, and ATM were enriched. In the lower BMI group, EGFR, PMS1, FH, TP53, and BAP1 were more common.

• These findings help generate hypotheses about how metabolism and tumor biology may interact during immunotherapy.

Advocacy

• Weight monitoring is simple, low cost, and already part of routine care. This abstract supports using those early changes more intentionally as part of treatment follow up.

• For people starting immunotherapy, this reinforces the value of asking the care team:

• How is weight being tracked

• What early changes matter

• When a nutrition consult or symptom review is useful

• Whether appetite loss, nausea, fatigue, or inflammation need fast support

Survivorship

• Weight change during treatment is more than a number on a scale. It can reflect energy balance, symptom burden, appetite, inflammation, hydration, muscle loss, steroid use, or fluid shifts.

• A small early increase can be reassuring. A drop in weight is useful information that can prompt supportive care sooner. That is where survivorship and treatment response connect in a real world way.

What it means for people with a KRAS mutation

For people with a KRAS mutation, this abstract matters because KRAS mutations were more common in the higher BMI group in this cohort. That does not mean KRAS causes the BMI effect. It does mean KRAS biology may be part of the broader metabolic and immune landscape that shapes response to treatment. This is a meaningful signal for future work, especially in lung cancer where KRAS is common and immunotherapy is widely used.

Bottom line

A little weight gain in the first month can be an encouraging early sign that immunotherapy based treatment is more likely to help, especially with chemo immunotherapy. It is one clue within the full clinical picture. Early weight loss deserves attention and support right away.

April 3, 2026 Publication status: Conference abstract published in the AACR Annual Meeting 2026 proceedings

Citation

Wang X, Pecci F, Santo V, et al. Early BMI increase as a predictive biomarker for immune checkpoint inhibitor ± chemotherapy efficacy in advanced NSCLC: Integrating clinical, genomic, and circulating proteomic data. Cancer Research. 2026;86(7 Suppl):Abstract 3631. AACR Annual Meeting 2026.