Placebo-controlled, Study of Concurrent Chemoradiation Therapy With Pembrolizumab Followed by Pembrolizumab and Olaparib in Newly Diagnosed Treatment-Naïve Limited-Stage Small Cell Lung Cancer (LS-SCLC) (MK 7339-013/KEYLYNK-013)

This study is looking for adults aged 18 or over who have been newly diagnosed with Limited-Stage Small Cell Lung Cancer. This means your cancer has been confirmed by a doctor and is only in your lung or close by, and has not spread to other parts of your body. You should not have had any previous treatment for this lung cancer, such as chemotherapy or radiation, before joining the study.

To be considered, you'll need to be generally well enough to take part, as measured by a doctor's assessment (your 'performance score'). You should also have healthy organ function and be expected to live for at least six months. Your doctors will also need to be confident that you can safely receive radiation treatment.

You won't be able to join if you have a mixed type of lung cancer (small cell and non-small cell at the same time), if your cancer has already spread, or if you need surgery for your cancer during the study. There are also specific rules about not being pregnant or breastfeeding, and using contraception if needed.

If you join this study, you will receive either standard chemoradiation therapy alone, or standard therapy combined with one or both of the new study drugs (pembrolizumab and olaparib). The drugs will be given in specific doses and ways, for example, olaparib is given twice a day. You will have regular visits to the clinic for treatments, check-ups, and tests like PET/CT scans and MRI scans to monitor your health and how the treatment is working.

Researchers will also collect samples, such as a tumour tissue sample, before treatment begins. You may also receive a specific type of radiation to the brain, called Prophylactic Cranial Irradiation (PCI), if your doctor recommends it. The total length of your participation will depend on the treatment plan and follow-up required for your group, but it will involve ongoing assessments and potentially taking study drugs for a set period, followed by long-term monitoring.