Treatment paradigms · for clinicians and informed patients

First-Line Systemic Therapy in Advanced Cancers

5/8/2024 · 7 min read · updated 24 Oct 2026

Bottom line

Test first (histology + biomarkers), then match: targeted therapy for driver-positive disease, immunotherapy ± chemotherapy for biomarker-selected tumours, ADCs increasingly moving earlier. Fitness, goals and access decide the rest.

Choosing the right first-line systemic therapy is crucial in managing advanced cancers. The treatment approach depends on cancer type, histology, molecular markers, and patient factors. From targeted therapies to immunotherapy and chemotherapy, precision medicine is reshaping cancer care. Read more to explore the latest guidelines, treatment strategies, and advancements in systemic therapy for advanced cancers!

Step 1 — Define the disease

Histology confirmed on adequate tissue (core > FNA). Save blocks for molecular tests.
Stage with appropriate imaging; confirm “advanced” really means incurable (oligometastatic disease may merit local therapy).
Fitness: ECOG PS, organ function, comorbidities, patient goals.

Step 2 — Biomarkers before first line

More first-line principles: biliary/gallbladder · endometrial · renal cell · medullary thyroid

Step 3 — Match the therapy

Driver-positive → targeted therapy first (e.g. osimertinib ± chemotherapy in EGFR-mutant NSCLC; alectinib/lorlatinib in ALK).
Driver-negative, immunogenic → checkpoint inhibitor ± chemotherapy (NSCLC, gastric, oesophageal, urothelial, HNSCC, cervix, endometrial dMMR, TNBC PD-L1+).
Target-defined ADCs → now first line in some settings (enfortumab vedotin + pembrolizumab in urothelial cancer).
Chemotherapy remains the backbone for many, and alone when IO/targeted options are unavailable.

Landmark first-line trials: median overall survival (months)

KEYNOTE-189: pembro + chemo22.0 mo

KEYNOTE-189: chemo10.6 mo

FLAURA2: osimertinib + chemo47.5 mo

FLAURA2: osimertinib37.6 mo

EV-302: EV + pembro31.5 mo

EV-302: platinum chemo16.1 mo

Medians from the cited publications; cross-trial comparison is not valid — different diseases and populations.

Sources: KEYNOTE-189 (OS 22.0 vs 10.6 mo, HR 0.60) · FLAURA2 (HR 0.77) · EV-302 (HR 0.47)

First-line principles by cancer

Click a cancer name above or below. Principles condensed from Dr. Senthil Kumar’s X threads; numbers as stated there.

Urothelial / bladder cancer

Confirm urothelial histology; document variant differentiation — it can change the pathway.
Cisplatin eligibility by Galsky criteria (any one: ECOG PS 2, CrCl <60 mL/min, grade ≥2 hearing loss or neuropathy, NYHA III).
Preferred first line: enfortumab vedotin + pembrolizumab, across cisplatin eligibility and PD-L1 groups.
EV unsuitable/unavailable: cisplatin-eligible → gemcitabine–cisplatin + nivolumab (up to 6 cycles), then nivolumab; platinum chemo then avelumab maintenance if no progression after 4–6 cycles (JAVELIN Bladder 100).
Test FGFR3 (validated assay) for later erdafitinib. Thread

Gallbladder / biliary tract cancer

Not all biliary tract cancer is biologically identical; pathology and baseline liver/biliary status matter.
Molecular testing early — HER2 IHC ± ISH, MSI/MMR, broad panel when possible.
ABC-02 set the gem–cis backbone; chemo-immunotherapy (KEYNOTE-966: pembrolizumab + GemCis, mOS 12.7 vs 10.9 mo, HR 0.83) is first line.
HER2 is a key gallbladder target; oligoprogression → consider local therapy, don’t abandon effective systemic therapy.
LMIC: if NGS unaffordable, prioritise HER2 IHC, then MMR/MSI. Thread

Endometrial carcinoma

First line has moved from chemotherapy alone to molecularly informed treatment — know MMR status.
Dostarlimab + carboplatin–paclitaxel (RUBY Part 1): dMMR/MSI-H 24-month PFS 61.4% vs 15.7% (HR 0.28); overall OS 44.6 vs 28.2 mo.
Cytoreduction when complete macroscopic resection is achievable. Thread

Renal cell carcinoma

Confirm histology (clear cell, papillary, chromophobe…) — it drives the regimen.
IO-based combinations are the first-line standard; triplets add toxicity: COSMIC-313 (cabozantinib + nivo/ipi) improved PFS 16.6 vs 11.2 mo but not OS (41.9 vs 42.0 mo, HR 1.02). Thread

Medullary thyroid cancer

Systemic therapy for advanced/metastatic MTC is a separate pathway from differentiated thyroid cancer; RET status guides choice. Thread

NSCLC

Broad NGS + PD-L1 before cycle 1; driver-positive → targeted therapy (osimertinib ± chemo in EGFR). See FLAURA2.

Breast cancer

ER/PR, HER2 (incl. HER2-low), germline BRCA; ADCs moving earlier. See DESTINY-Breast11 and ESR1 brief.

Colorectal cancer

RAS, BRAF V600E, MMR/MSI, HER2 first; dMMR → immunotherapy. See dostarlimab in MSI-H rectal and ASCO GI 2026.

Gastric / GEJ cancer

HER2, MMR/MSI, PD-L1 CPS, claudin 18.2 before first line; nivolumab benefit concentrated at CPS ≥5 (CheckMate 649). See ASCO GI 2026.

Step 4 — Practicalities

Check drug access, insurance (CMCHIS, PM-JAY) and travel burden before promising a regimen.
Baseline TSH, cortisol, LFTs before immunotherapy; LVEF before anti-HER2; ophthalmic/ILD counselling with relevant ADCs.
Discuss palliative care early — improves quality of life and, in one RCT, survival (Temel, NEJM 2010).

Step 5 — Read the evidence critically

Overall survival is the gold standard, but crossover dilutes it. In KEYNOTE-189, more than half of chemo-arm patients later received anti-PD-(L)1 therapy, yet OS still favoured upfront pembrolizumab (HR 0.60; 5-year OS 19.4% vs 11.3%). [JCO 2023]
PFS gains are meaningful only with acceptable toxicity. KEYNOTE-189 PFS was 9.0 vs 4.9 months (HR 0.50). [JCO 2023] Ask whether the control arm reflects the standard where you practise.
Subgroups generate hypotheses, they do not prove them. PD-L1 cut-offs matter in some diseases: in CheckMate 649 the nivolumab benefit was concentrated in PD-L1 CPS ≥5 (OS 14.4 vs 11.1 months, HR 0.71). [Lancet 2021]
Quality of life and time toxicity (days spent in hospital or travelling) matter as much as medians for many patients.

Step 6 — Plan for the whole journey

Define the response assessment schedule (usually every 2–3 cycles / 6–12 weeks) before starting.
Decide early what the second line would be, so tissue, biomarkers and fitness are preserved for it.
Treatment holidays or de-escalation (e.g. stopping immunotherapy at 2 years in responders, as in KEYNOTE-189’s 35-cycle cap) reduce cost and toxicity.
Re-biopsy or liquid biopsy at progression on targeted therapy to find resistance mechanisms (e.g. MET amplification after osimertinib).

Special situations

Elderly or frail patients: geriatric assessment (G8 screening) predicts chemotherapy toxicity better than age alone; single-agent or dose-adjusted regimens are often appropriate.
Organ dysfunction: many targeted drugs and immunotherapies need little renal adjustment, whereas cisplatin, pemetrexed and capecitabine do — check creatinine clearance.
Pregnancy and fertility: discuss sperm/oocyte preservation before gonadotoxic therapy when relevant.
Pre-existing autoimmune disease or organ transplant: immunotherapy needs specialist discussion; transplant rejection is a real risk.

Step 7 — Palliative care is not “giving up”

Early integrated palliative care improved quality of life, reduced depression and was associated with longer survival (median 11.6 vs 8.9 months) in metastatic NSCLC. [NEJM 2010] Symptom control, nutrition, psychosocial support and advance-care discussions belong in the first visit, not the last.

Opinion: in Indian practice, the single most impactful first-line decision is often getting the right biomarker result before cycle 1 — a week's delay for an EGFR or ALK result is usually worth it.

Sources

Educational summary, not medical advice. Opinions are labelled as such and are the author's own. Approvals and availability in India (CDSCO) may differ from the US/EU.

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