What Is BAT? Best Available Treatment Explained for Biotech Investors

BAT stands for best available treatment. In clinical trials, it is a type of control arm where patients receive the best treatment option available to them under the protocol.

Why BAT is used

BAT is often used when there is no single standard treatment for all patients. Different patients may have different prior therapies, mutations, health status or treatment options.

Why BAT can be complicated

BAT is flexible, but that flexibility creates complexity. Different patients in the control arm may receive different treatments. Some may receive active therapy. Others may receive observation or lower-intensity treatment.

If BAT performs better than expected, the experimental drug may have a harder time showing benefit.

BAT and modern medicine

Historical BAT assumptions can become outdated. If a trial is designed using old survival estimates but enrolls patients after new therapies become common, the control arm may perform better than expected.

BAT in event-driven trials

In event-driven trials, stronger BAT can delay events. Investors may interpret delayed events as evidence that the experimental drug works. But if the trial is blinded, the delay may be coming from the BAT arm.

Questions investors should ask about BAT

Ask what treatments are allowed, whether investigators can choose among multiple options, how modern the BAT options are, whether BAT assumptions were based on old data, whether targeted or combination therapies are allowed and whether the trial stratifies for key risk factors.

Bottom line

BAT can be a fair and ethical control arm, but it is not simple. The key question is: Is the experimental drug beating a modern and realistic control arm, or only outperforming old historical expectations?