Key Ideas

Treating "KRAS-mutant lung cancer" as one disease is quickly becoming outdated. Beyond G12C, allele-specific inhibitors (for G12D) and pan-RAS inhibitors are producing genuinely meaningful response rates, each with a distinct toxicity profile, and roughly 100 RAS-directed compounds are now in clinical development. The near-term challenge won't be pharmacology, it will be enrolling enough patients across an increasingly fragmented set of molecular subgroups to generate the data needed to know which drug fits which patient.

KRAS Is Not One Disease

KRAS G12C is not the only KRAS mutation worth worrying about, and I think that idea is very close to being obsolete. KRAS biology and epidemiology vary meaningfully by specific allele, and I've stopped referring to "KRAS-mutant disease" as a single category; I don't think it's a useful framing given how differently these subtypes behave and respond to therapy. My hope for this field isn't a single molecule and a single line of therapy, but a genuine toolkit of options for KRAS-mutated disease, developed and sequenced based on the specific allele involved. At progression on a G12C inhibitor, I routinely check ctDNA specifically hoping to find other alterations that may become targetable, now or in the near future.

Pan-RAS Inhibition: A New Pharmacologic Approach

A useful way to think about the growing RAS-inhibitor landscape: molecules can be allele-specific (like sotorasib and adagrasib, both allele-specific, RAS-GDP-state, covalent inhibitors targeting G12C) or pan-RAS/pan-KRAS; they can target the RAS-GTP ("ON") state or the RAS-GDP ("OFF") state; and they can work as covalent or non-covalent inhibitors, or as degraders or molecular glues rather than simple inhibitors. This creates a genuinely multidimensional landscape that's difficult to visualize but useful to keep in mind when thinking about a new compound's likely activity and side-effect profile.

Daraxonrasib, a pan-RAS inhibitor, was first widely discussed in pancreatic cancer, where it produced a doubling of overall survival and a tripling of response rate compared with chemotherapy, genuinely transformative data for that field. Daraxonrasib works through a novel pharmacologic mechanism, binding the active (GTP-bound) state of RAS and forming an unnatural molecular complex that blocks RAS function, rather than directly and simply shutting the protein down.

Daraxonrasib has also been tested in NSCLC, with data presented roughly a year ago showing a response rate just under 40%, duration of response of 15 months, and time to response around 1.5 months, across multiple KRAS alleles (G12A, G12B, and others) responding similarly. Because daraxonrasib inhibits wild-type RAS as well as mutant forms, its side-effect profile differs meaningfully from allele-specific inhibitors, notably, rash occurs in up to 90% of patients (a side effect publicly documented by a patient in the New York Times), something the field will need to learn to manage as this drug moves forward. A second-line, randomized registrational trial (daraxonrasib versus docetaxel) is now enrolling in NSCLC, modeled on the trial design that transformed pancreatic cancer treatment.

G12D-Specific Therapy: A New Allele, A New Molecule

KRAS G12D occurs in NSCLC at a frequency roughly comparable to EGFR exon 20 insertions, uncommon, but a genuine target population. Zoldonrasib is a covalent, G12D-selective inhibitor (structurally related to daraxonrasib but selective, rather than pan-RAS, sparing wild-type RAS and avoiding the associated rash). Phase 1 data presented earlier this year showed a roughly 50% response rate in patients who had not yet received docetaxel, with minimal toxicity overall, low enough that a first-line trial adding zoldonrasib to standard chemo-immunotherapy specifically in G12D-mutated NSCLC is starting later this year, notably the first randomized trial to test chemo-immunotherapy specifically in a G12D-selected population. A separate G12D-directed protein degrader, setidegrasib (rather than a simple inhibitor), has also shown meaningful activity (roughly 35-40% response rate) in an all-comers, not docetaxel-naive, population, with a phase 3 trial versus docetaxel now starting.

What This Means Going Forward

There are roughly 100 RAS inhibitors currently in clinical development, a genuinely new situation for a target that, until recently, had none. My honest answer to "which one is best" is that I don't know yet, and I'm more interested in identifying the right overall strategy (allele-specific versus pan-RAS, and in which clinical scenario) than in declaring a single winner today. There's also encouraging, if still very early, press-release data on combining a RAS inhibitor with a PRMT5 inhibitor in MTAP-deleted pancreatic cancer, showing a 90% response rate in some patients, suggesting even more precision-medicine layering may be coming.

The most significant practical concern I have isn't chemistry, it's enrollment. When we looked at our own population, only about 30% of patients with metastatic KRAS G12C NSCLC were eligible for available clinical trials. Thirty percent of an already small population is probably not enough to adequately power all the trials this expanding pipeline will require, a genuine structural bottleneck for the field.

For Patients

Not all KRAS mutations in lung cancer are the same, and different specific KRAS changes increasingly need different targeted treatments. Newer drugs now target specific subtypes beyond the most common one (G12C), including one for a subtype called G12D, and a different kind of drug that targets multiple RAS mutations at once (a pan-RAS inhibitor), already showing major benefit in pancreatic cancer and now being studied in lung cancer too. Ask your care team about the specific KRAS subtype in your tumor's genetic testing and whether a clinical trial matched to that subtype might be available.

Key Takeaways

  • KRAS-mutated lung cancer should no longer be treated as a single disease category; different specific KRAS alleles have meaningfully different biology, epidemiology, and treatment response.

  • Daraxonrasib, a pan-RAS inhibitor that also inhibits wild-type RAS, shows response rates near 40% across multiple KRAS alleles in NSCLC, with a distinct toxicity profile (rash in up to 90% of patients) requiring proactive management.

  • Zoldonrasib, a G12D-selective covalent inhibitor, shows roughly 50% response rates with minimal toxicity, and is moving into first-line combination testing specifically in G12D-mutated NSCLC.

  • Roughly 100 RAS-directed compounds are currently in clinical development, spanning allele-specific and pan-RAS approaches, covalent and non-covalent mechanisms, and inhibitors, degraders, and molecular glues.

  • The central bottleneck for this expanding pipeline is not drug development but clinical trial enrollment; only about 30% of patients with metastatic KRAS G12C NSCLC are currently eligible for available trials.

References

  1. Bekaii-Saab TS, et al. Daraxonrasib versus chemotherapy in previously treated metastatic pancreatic ductal adenocarcinoma (RASolution/RASolute 302).

  2. Punekar SR, et al. Daraxonrasib in KRAS-mutated NSCLC. Presented at the 2025 ASCO Annual Meeting.

  3. Arbour KC, et al. Zoldonrasib (RMC-9805) in KRAS G12D-mutated NSCLC. Presented at the 2025-2026 AACR Annual Meetings.