Immunotherapy, Chemotherapy, Radiotherapy and Surgery for Synchronous Oligo-metastatic NSCLC

Non-small cell lung cancer (NSCLC) continues to be the leading cause of cancer-related mortality worldwide. Even with adjustment for age NSCLC is responsible for almost 20% of cancer-related deaths. Recent years have brought tremendous progress in the understanding of the disease, its underlying biology and the development of effective therapies. Traditionally, NSCLC has been treated with surgery, platinum-based chemotherapy or radiotherapy alone or in combination, depending on tumour stage, tolerability of expected side effects and prognosis. Various strategies are currently being pursued in order to increase the patient population that may benefit from immunotherapy and to further improve the outcome of patients with NSCLC.

The CHESS clinical trial is for patients with NSCLC that has progressed to a small number of other parts of the body (oligo-metastatic) and has not been previously treated, or after surgical resection of a single metastasis (central nervous system or adrenal). The trial aims to reduce the risk of systemic progression and thereby improve progression free survival. Participants will receive induction treatment consisting of immunotherapy combined with platinum-based doublet chemotherapy and stereotactic body radiotherapy (SBRT) that will be given to all oligo-metastatic locations. SBRT started early and concurrently with immunotherapy aims at enhancing a postulated immune effect and simultaneously effectively control the macro-metastases.

Preclinical data have shown a strong immune-enhancing effect of radiotherapy, especially when delivered to small volumes, in high-single fraction doses and over a short period of time. Consequently, stereotactic body radiotherapy (SBRT) is currently being intensively investigated as a partner for systemic immunotherapy. Earlier clinical studies generated proof-of-principle data for the synergistic effects of combined radiotherapy and immunotherapy. Chemotherapy and high-dose radiotherapy are well known triggers of immunogenic cell death and are therefore highly promising partners for combination with immunotherapy.

The sub-group of patients with "oligometastatic" disease was originally described by Hellman and Weichselbaum in 1995. In line with this concept, the current NCCN and ESMO guidelines describe that Stage IV NSCLC patients presenting with solitary metastases can be treated with curative intent using local surgery and/or radiotherapy. Local treatment for oligo-metastatic NSCLC has been adopted rapidly in the oncological community and one reason is the progress made in the fields of surgery and radiotherapy, both becoming less toxic (minimally invasive surgery) and simultaneously less toxic and more effective (precision radiotherapy), respectively. SBRT allows treatment of small peripheral primaries and metastases at virtually all anatomical locations with a favourable therapeutic ratio of local tumour control rates >90% and low rates of toxicity. Simultaneously, minimally invasive surgery for early and locally advanced NSCLC today achieves excellent local tumour control with low rates of toxicity.

Patients with a limited number of metastases - oligometastatic disease - are currently treated with combined radical local treatment for all active lesions (locoregional primary and metastases) and their prognosis is better as compared to patients who receive systemic treatment only for widespread metastatic disease. However, the majority of patients still develop systemic disease progression indicating the urgent clinical need for more effective systemic treatment to control subclinical disease.

All CHESS trial participants will receive induction treatment with the immunotherapy drug durvalumab, standard platinum-chemotherapy and radiation therapy of the lung cancer metastases (SBRT). Durvalumab is a human monoclonal antibody carefully engineered to attach to immune cells to stimulate their activity against cancer cells. There are now several approved antibodies for the treatment of cancer or other diseases. Standard platinum-chemotherapy includes treatment with carboplatin and paclitaxel.

After three months of induction treatment the status of the lung cancer will be restaged. If the primary lung cancer is stable or has not increased in size it will be surgically removed if possible or, alternatively, treated with radiation therapy. Treatment with durvalumab will continue until the disease relapses or for a maximum of one year from the start of induction treatment. If the lung cancer has increased in size at the time of the three month restaging all trial treatment will stop and the study doctor will discuss other treatment options that are available.

The efficacy, safety and tolerability of combining immunotherapy with standard platinum-chemotherapy and SBRT will be evaluated in the CHESS clinical trial.

Encouraged by the positive results of the POSEIDON trial, we amended the CHESS protocol to include a second cohort of additional 47 patients who will receive tremelimumab, in addition to the protocol treatment of the original CHESS protocol (e.g., durvalumab, platinum-based doublet chemotherapy, and SRBT to the oligo-metastatic lesions, followed by definitive local treatment for patients that have not progressed at the time of restaging).

Objectives and endpoints, patient selection and statistical assumption remain the same as for cohort 1 in the original protocol.