⚠ Before you start: rule out a targetable driver
This pathway applies only after molecular testing is negative for actionable alterations. In driver-positive disease (especially EGFR/ALK), single-agent immunotherapy is ineffective and can increase toxicity — targeted therapy is preferred. Also confirm PD-L1 (22C3 IHC) and histology.
EGFRALKROS1
BRAF V600EMET exon 14RET
NTRKKRAS G12CHER2
PD-L1 ≥ 50%High expression
Pembrolizumab monotherapyPreferred
Single-agent IO is a reasonable first choice for high PD-L1, low burden, asymptomatic disease. Spares chemotherapy toxicity.
Chemo + pembrolizumabAlternative
Higher response rate — favor when disease is bulky or symptomatic and a fast response matters. Histology-dependent backbone (see below).
Atezolizumab or cemiplimab monotherapyAlternative
Other single-agent IO options for high PD-L1.
PD-L1 1–49%Intermediate
Nonsquamous
Carboplatin + pemetrexed + pembrolizumabPreferred
Chemo-IO is preferred across PD-L1 < 50%. Pemetrexed only in nonsquamous.
Squamous
Carboplatin + (nab-)paclitaxel + pembrolizumabPreferred
No pemetrexed and no bevacizumab in squamous histology.
Nivolumab + ipilimumab (± 2 cycles chemo)Alternative
Dual-IO option; chemo-free or limited-chemo backbone. Consider in select patients.
Pembrolizumab monotherapyLess preferred
Allowed for PD-L1 ≥ 1% but generally less preferred than chemo-IO in the 1–49% range.
PD-L1 < 1%Negative
Nonsquamous
Carboplatin + pemetrexed + pembrolizumabPreferred
Chemo-IO benefit in KEYNOTE-189 was seen regardless of PD-L1, including PD-L1 < 1%.
Atezo + bevacizumab + carbo + paclitaxelAlternative
IMpower150 quadruplet — an option in nonsquamous (bevacizumab-eligible).
Squamous
Carboplatin + (nab-)paclitaxel + pembrolizumabPreferred
KEYNOTE-407 benefit also independent of PD-L1.
Nivolumab + ipilimumab + 2 cycles chemoAlternative
Dual-IO + limited chemo; an option for PD-L1 < 1%.
⚠ Caveats & pitfalls
- Driver mutations trump everything. Confirm EGFR/ALK/ROS1/etc. negative before IO. IO is ineffective and potentially harmful in EGFR/ALK+; targeted therapy is first-line there.
- Pemetrexed = nonsquamous only. Do not use in squamous histology.
- Bevacizumab is contraindicated in squamous (hemoptysis risk) and used cautiously with brain mets / anticoagulation.
- IO contraindications/caution: active autoimmune disease, solid-organ transplant, chronic high-dose steroids.
- Performance status: ECOG 2 patients often get single-agent chemo or attenuated regimens; most pivotal trials enrolled PS 0–1.
- PD-L1 assay matters: pembrolizumab decisions use the 22C3 IHC assay (TPS).
High-yield board points
- KEYNOTE-024: pembrolizumab monotherapy beat platinum chemo for PD-L1 ≥ 50%.
- KEYNOTE-189: carbo/pemetrexed + pembro in nonsquamous — OS benefit across all PD-L1 strata.
- KEYNOTE-407: carbo/taxane + pembro in squamous — OS benefit regardless of PD-L1.
- CheckMate 9LA: nivo + ipi + 2 cycles of chemo (limited chemo to control early progression).
- CheckMate 227: nivo + ipi for PD-L1 ≥ 1% (chemo-free dual IO).