Overview and key takeaways

McGrath et al. (2024) focus on one stubborn problem.

ER-positive breast cancer often responds first, then learns to survive.

The paper argues that two survival states help bridge that gap:

• autophagy — a self-recycling program

• senescence — a growth-arrest state that may still be reversible

The big picture

Roughly 70% of breast cancers are hormone-receptor-positive.

That makes endocrine therapy central to care.

The main drug families are:

• aromatase inhibitors such as letrozole, anastrozole, and exemestane

• SERMs such as tamoxifen

• SERDs such as fulvestrant

CDK4/6 inhibitors improved outcomes further.

Even so, resistance still develops in many patients over time.

McGrath et al. (2024) argue that resistance often does not appear out of nowhere.

It may grow out of a quieter phase first.

That quieter phase is where autophagy and senescence matter most.

The core argument in one sequence

Treatment pressure starts.

Some cancer cells die.

Some survive by slowing down, recycling resources, and holding position.

While they are held in that state, they may accumulate the molecular changes needed for later escape.

The proposed model looks like this:

Endocrine therapy or CDK4/6 inhibition → autophagy and senescence → survival under pressure → later resistance mutations or rewiring

What the review treats as established

The paper brings together several points with fairly strong support:

• endocrine resistance remains a major reason ER-positive disease progresses

• autophagy is repeatedly seen in antiestrogen-resistant models

• senescence can be induced by antiestrogens and CDK4/6 inhibitors

• senescence in cancer cells is not always permanent

• dormant or growth-arrested cells may still help drive later relapse

What is still unsettled

The authors are careful about what is not proven yet.

Key open questions include:

• when to block autophagy

• when to deliver a senolytic

• how to measure these states reliably in patients

• whether blocking autophagy might also blunt useful treatment effects in some settings

• how to target surviving cells without adding too much toxicity

Why this matters clinically

Once fully resistant disease is established, the biology is often more tangled.

There may be several resistance mechanisms at once.

That makes later rescue harder.

McGrath et al. (2024) push an earlier question.

Can we interrupt the survival phase before durable resistance locks in?

That is the real shift here.

It moves the focus from reacting to resistance toward trying to stop resistance from maturing.

Bottom line

McGrath et al. (2024) do not argue that endocrine therapy has failed.

They argue that treatment pressure can leave behind a protected population.

That population may sit in autophagy, senescence, or both.

If future treatment can clear those held cells at the right time, acquired resistance may become harder to build.