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Lung adenocarcinoma — systemic therapy

TL;DR — Systemic treatment begins with a completed biomarker set, not with a generic “stage IV adenocarcinoma” regimen. Actionable EGFR, ALK, ROS1, BRAF V600E, MET exon-14, RET, NTRK, KRAS G12C, and HER2 states route patients into distinct evidence paths; PD-L1 is interpreted only after those drivers are known (Lindeman 2018, PMID 29398453). In driver-negative disease, pembrolizumab plus platinum-pemetrexed improves survival across PD-L1 strata, while checkpoint monotherapy is an option for selected high-PD-L1 tumors (Gandhi 2018, PMID 29658856; Reck 2016, PMID 27718847). Pemetrexed is specifically favored in nonsquamous histology because randomized interaction analyses showed better outcomes than gemcitabine or docetaxel in nonsquamous but not squamous disease (Scagliotti 2011, PMID 21119545). Progression is classified as systemic, oligoprogressive, CNS-dominant, or transformed before the next treatment is chosen. Performance status, symptom tempo, organ function, drug interactions, access, and patient priorities can outweigh small cross-trial differences.

Pre-treatment minimum dataset

Domain Required information Why it changes treatment
Diagnosis Adenocarcinoma confirmation; adequate IHC; exclude metastasis from another primary Prevents lineage-inappropriate therapy
Extent TNM edition, sites, measurable disease, brain MRI when indicated Defines local therapy, urgency, and CNS-active drug need
Genotype Broad DNA panel plus RNA fusion capability; EGFR, ALK, ROS1, BRAF, KRAS, MET, RET, NTRK, ERBB2 Routes to matched therapy
Immune biomarker PD-L1 assay and TPS Helps choose mono- versus chemo-immunotherapy after genotype
Patient state ECOG PS, symptoms, weight, organ function, comorbidity, medications Determines feasibility and dose
Goals Survival, symptom relief, toxicity tolerance, route, visits, financial/logistical burden Defines net benefit

Plasma genotyping can shorten time to an actionable result and complement tissue, but a negative plasma result does not exclude a driver because shedding varies (Leighl 2019, PMID 30988079; Rolfo 2021, PMID 34246791).

First-line routing table

Biomarker state Evidence-led first-line route Pivotal evidence Do not assume
EGFR exon 19 deletion/L858R Osimertinib; selected intensification with chemotherapy or amivantamab-lazertinib FLAURA (PMIDs: 29151359, 31751012); MARIPOSA programme (PMID 38942080) PD-L1-high means IO first
EGFR exon 20 insertion Amivantamab + carboplatin-pemetrexed PAPILLON (PMID 37870976) Conventional-dose EGFR TKI sensitivity
ALK fusion CNS-active ALK inhibitor ALEX, CROWN (PMIDs: 28586279, 33207094) Crizotinib remains equivalent
ROS1 fusion CNS-active ROS1 inhibitor Entrectinib, repotrectinib (PMIDs: 31838015, 38197815) Systemic ORR predicts CNS prevention
RET fusion Selpercatinib LIBRETTO-431 (PMID 37870973) Chemo-IO is equivalent despite PD-L1
BRAF V600E BRAF + MEK inhibitor Dabrafenib-trametinib, PHAROS (PMIDs: 28919011, 37270692) Non-V600 BRAF behaves identically
MET exon-14 skipping Capmatinib or tepotinib GEOMETRY, VISION (PMIDs: 32877583, 32469185) IHC overexpression is the same biomarker
NTRK fusion Larotrectinib or another validated TRK inhibitor Tissue-agnostic pooled evidence (PMID 29466156) A DNA rearrangement is always functional
No actionable driver, PD-L1 ≥50% Checkpoint monotherapy or chemo-IO KEYNOTE-024/189 (PMIDs: 27718847, 29658856) Monotherapy always best tolerated or sufficient
No actionable driver, PD-L1 <50% Platinum-pemetrexed + pembrolizumab KEYNOTE-189 (PMID 29658856) PD-L1-negative means no immune benefit

KRAS G12C and HER2-mutant therapies have historically been established after prior systemic therapy; first-line trials are active and jurisdictional labels change. Verify current guidance before applying the table (PMIDs: 36764316, 37694347).

EGFR first-line intensification

Osimertinib improved PFS and OS over first-generation EGFR inhibitors in FLAURA (Soria 2018, PMID 29151359; Ramalingam 2020, PMID 31751012). Subsequent programs showed longer PFS with added platinum-pemetrexed or with amivantamab-lazertinib, at the cost of more toxicity, visits, and supportive care (FLAURA2, PMID 37937763; MARIPOSA, PMID 38924756).

Selection requires absolute—not only relative—benefit, CNS disease, co-mutations, symptom burden, age/frailty, venous-thromboembolism risk, infusion feasibility, quality of life, and post-progression options. A live PubMed search on 2026-08-29 found no prospectively validated biomarker that assigns osimertinib monotherapy versus either intensification strategy; available publications report efficacy or secondary risk analyses rather than a treatment-by-biomarker decision rule (FLAURA2, PMID 37937763; MARIPOSA secondary analysis, PMID 38942080).

Chemotherapy architecture

Pemetrexed is the nonsquamous antimetabolite backbone. Histology-treatment interaction across phase III trials showed superiority for pemetrexed in nonsquamous disease and inferiority in squamous disease (Scagliotti 2011, PMID 21119545).

Component Role Main limiting toxicities
Cisplatin Higher emetogenic, renal, neurologic, auditory burden; curative regimens often cisplatin-based Nephrotoxicity, ototoxicity, neuropathy, nausea
Carboplatin Common metastatic partner with easier administration Thrombocytopenia, myelosuppression
Pemetrexed Adenocarcinoma/nonsquamous backbone; maintenance-capable Cytopenias, fatigue, mucositis; folate/B12 support required
Paclitaxel/nab-paclitaxel Alternative taxane backbone Neuropathy, myelosuppression; infusion reaction with solvent formulation
Bevacizumab Anti-VEGF option in selected nonsquamous disease Bleeding, hypertension, proteinuria, thrombosis, wound healing

Bevacizumab-containing IMpower150 improved outcomes as a four-drug regimen in metastatic nonsquamous NSCLC, but bleeding risk, anticoagulation, uncontrolled hypertension, recent surgery, and regimen complexity matter (Socinski 2018, PMID 29863955).

Maintenance therapy

Continuation pemetrexed, with or without pembrolizumab according to the induction regimen, preserves an active component after platinum completion. Maintenance is not biologically “nothing”; it continues cumulative fatigue, marrow, renal, immune, visit, and financial burdens.

Stopping platinum after a finite induction avoids cumulative toxicity. Stopping all therapy versus maintenance should be framed with the trial population, response, tolerance, residual burden, and patient preference.

Response assessment

Pattern Interpretation Typical next step
Global response/stability Current therapy controls dominant clones Continue with planned monitoring
Oligoprogression Limited resistant site(s), remainder controlled Consider local therapy plus continued systemic suppression
CNS-only progression Sanctuary pharmacology or resistant CNS clone CNS-active switch and/or local therapy
Widespread progression Systemic resistance Re-biopsy/plasma if actionable; change regimen
Apparent early IO growth True progression, inflammation, infection, or mixed response Clinical stability and confirmatory assessment govern; do not invoke pseudoprogression reflexively
Abrupt phenotype change Possible transformation Tissue biopsy when feasible

RECIST standardizes measurements but does not capture symptoms, ctDNA, lesion-level discordance, or pharmacologic CNS control. Mixed responses are biologically informative (Hobor 2024, PMID 38871738).

Later-line targeted therapy

State Evidence-supported later-line option Quantitative anchor
EGFR T790M after earlier TKI Osimertinib PFS 10.1 vs 4.4 mo versus platinum-pemetrexed, HR 0.30 (PMID 27959700)
KRAS G12C Sotorasib or adagrasib CodeBreaK 200 PFS HR 0.66; KRYSTAL-1 ORR 42.9% (PMIDs: 36764316, 35658005)
HER2 mutation T-DXd DESTINY-Lung01 ORR 55%; ILD 26% at original dose (PMID 34534430)
MET exon-14 Capmatinib/tepotinib if not previously used Single-arm response cohorts (PMIDs: 32877583, 32469185)
RET/ROS1/ALK Next inhibitor selected by prior drug, CNS state, and resistance Avoid a generic generation ladder

After chemo-immunotherapy without a target

Docetaxel, often with an antiangiogenic partner where approved, remains a later-line comparator. Benefits are modest and toxicities substantial. Histology, prior neuropathy, marrow reserve, pulmonary risk, and goals shape whether chemotherapy, a trial, local therapy, or symptom-focused care offers the best net value.

Rechallenge should distinguish relapse after a treatment-free interval from progression on therapy. Repeating a failed mechanism without a changed biological premise is not evidence-based sequencing.

CNS disease and oligoprogression

Brain metastases require lesion size, number, symptoms, edema, prior radiation, and drug CNS activity. Symptomatic lesions generally need local-treatment assessment regardless of systemic regimen (Vogelbaum 2022, PMID 34932393).

Randomized phase II oligometastatic trials found longer PFS and OS with local consolidation in selected nonprogressing NSCLC, but they predated many modern CNS-active targeted therapies (Gomez 2019, PMID 31067138; Iyengar 2018, PMID 28973074).

Supportive and palliative care

Early palliative care integrated with oncology improved quality of life and mood, reduced aggressive end-of-life care, and was associated with longer median survival in metastatic NSCLC (Temel 2010, PMID 20818875). It is concurrent care for symptoms and decisions, not a synonym for stopping anticancer therapy.

Systemic therapy should be reassessed when toxicity, declining function, repeated hospitalization, or progression makes the probability of benefit lower than burden. Treatment beyond progression needs a defined rationale and stop rule.

Open questions

  • Which biomarker selects EGFR first-line intensification rather than osimertinib alone?
  • What is the optimal lifetime sequence for ALK, ROS1, RET, MET, and HER2 disease after CNS or compound resistance?
  • Can ctDNA-directed switching improve survival without premature abandonment of effective therapy?
  • Which regimen best treats STK11/KEAP1-mutant driver-negative adenocarcinoma (PMIDs: 29773717, 34740862)?
  • What is the best post-chemo-IO sequence for frail patients excluded from pivotal trials?
  • When does local ablation plus continued targeted therapy outperform immediate systemic switching?

References

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