Basal-like 2 triple-negative breast cancer: the decisions you may face

Cancer page →Second-opinion finder →

1 treatment setting, 0 with more than one named option. Each section lays out the options the standard of care names, what each is for, the trials behind them with their recorded results, the side effects and cautions on record, and questions to ask. Built from the cancer page's standard-of-care rows; nothing here is advice for your case.

Early / localised

Stage II to III

One path named

As for triple-negative disease (KEYNOTE-522 regimen); the low pathological complete response rate in this subtype is a research observation, not a reason to change treatment.

The path, in plain words

PembrolizumabApprovedMonoclonal antibody (anti-PD-1)

Pembrolizumab is a PD-1 blocking antibody approved in more than 40 settings, from melanoma and lung cancer to the first tumour-agnostic approval for mismatch-repair-deficient tumours in 2017, and before and after surgery in triple-negative breast cancer. A subcutaneous form arrived in 2025, and it is the backbone partner for ADCs and personalised neoantigen vaccines.

The evidence behind it

KEYNOTE-522 Phase 3 NCT03036488 20201,174 peopleevidence 73
Tests Pembrolizumab
Early-stage (II-III) TNBC: pembrolizumab + chemotherapy before surgery, pembrolizumab after
Show survival figures (1)
Averages across everyone diagnosed, often years ago. Your stage, subtype, age, fitness and the treatment you receive matter more than the average, and the numbers are improving quickly.
EFS HR 0.63; OS HR 0.66 (5-year); 7-year OS 85.1% vs 77.2%.
Pathologic complete response (ypT0/Tis ypN0) (%): Pembrolizumab + chemotherapy 64.8 (n=401) vs Placebo + chemotherapy 51.2 (n=201) · source

The main trade-offs on record

Pembrolizumab all recorded rates →

Side effect	Any grade	Grade 3+
Hypothyroidism (immune-mediated) · Pooled monotherapy data, >2,800 patients	8%	-
Pneumonitis (immune-mediated) · Pooled monotherapy data, >2,800 patients	3.4%	-
Colitis (immune-mediated) · Pooled monotherapy data, >2,800 patients	1.7%	-
Hepatitis (immune-mediated) · Pooled monotherapy data, >2,800 patients	0.7%	-

No pharmacokinetic interactions expected (antibody). See the irAE guide for toxicity management.

Rates from the label or pivotal trial as recorded on the product page; each grade 3+ figure links to its source.

Questions to ask about this decision

Is Pembrolizumab the only reasonable path for me, or is there a trial, a different sequence or a wait-and-see option?
Why: A single standard does not mean a single choice; timing and trials are decisions too.
What is each option trying to achieve: cure, long control, or relief of symptoms, and over what time?
Why: The aim shapes how much side effect and disruption is worth accepting.
How closely do I match the people in KEYNOTE-522, and does that change what the results mean for me?
Why: Trial populations are selected; age, fitness, prior treatment and biomarkers all affect how far results carry.
Which side effects of Pembrolizumab are most likely for me, which are reversible, and which would make us stop?
Why: The recorded rates below come from labels and trials; your own risk depends on dose, other medicines and your health.
What happens if I delay, or decline this step for now? Is the decision reversible?
Why: Some decisions can wait for a second opinion or a trial slot; others cannot. Knowing which is part of the choice.
For my situation (stage ii to iii), which of the standard options do you recommend and why?
Why: Guideline options include: As for triple-negative disease (KEYNOTE-522 regimen); the low pathological complete response rate in this subtype is a research observation, not a reason to change treatment.
Am I a candidate for Pembrolizumab, and what side effects should I expect?
Why: Knowing the expected toxicities helps you plan work, family, and supportive care.
How do the results of KEYNOTE-522 apply to someone like me?
Why: Trial populations differ from individual patients; ask how closely you match.

Add these to your appointment list, or take the full question set for this cancer.

How to read this page. Options and results come from OnCo records with their sources; the settings are the standard-of-care rows on the cancer page, and the lines of therapy are on the sequencing grid. Where a setting names one path, the choice is usually about timing, trials and where to be treated: see expert centres. OnCo is orientation, not medical advice.

Living with cancer·Standard of care