Small Cell Lung Carcinoma Trial With Nivolumab and IpiliMUmab in LImited Disease

At the time of diagnosis, 30% of patients with small cell lung carcinoma (SCLC) will have limited stage disease, now called stage I-IIIB (IASLC). The outcome of limited disease SCLC is still poor, with a median survival of 16 to 24 months with current forms of treatment and only 15-25% long term survivors.

Combining chemotherapy and thoracic radiotherapy is the standard treatment approach in limited-stage SCLC with a combination of platinum compounds (cis- or carboplatin) and etoposide and cisplatin (PE) as the backbone regimen. Concurrent chemo-radiotherapy is superior to sequential treatment and early thoracic irradiation starting with first or second cycle of chemotherapy appears beneficial. Hyperfractionated accelerated radiotherapy has been shown to be more efficacious than radiotherapy given in a long overall treatment time. However, availability and routine-use of hyperfractionated radiotherapy remains a matter of debate. Therefore, in this trial, both radiotherapy schedules of accelerated twice-daily administration or once-daily radiotherapy are accepted. The choice of schedule is a stratification factor for randomisation.

The adaptive immune response is triggered via effector T-cells, antigen-presenting cells (APCs) and co-stimulatory signals mediated by T cell receptors such as CD28. The interplay of these signals results in the activation and clonal proliferation of T cells.

T-cell proliferation is tightly regulated in order to avoid autoimmunity. The balance between co-stimulatory signals mediated by CD28 and co-inhibitory signals via so called immune checkpoint receptors is crucial for the maintenance of self-tolerance and to protect tissues from damage during normal immune response. After activation, T-cells express the immune checkpoint receptors cytotoxic T-lymphocyte antigen-4 (CTLA-4) and programmed cell death protein 1 (PD-1).

CTLA-4- and PD-1 expressing T-cells play a critical role in maintaining self-tolerance but are also responsible for non-responsiveness to tumour antigens. Cancer cells escape from im-mune surveillance by expressing immune checkpoint receptors. The goal of immune check-point inhibitor therapies is not to activate the immune system to attack particular targets on tumour cells, but rather to remove inhibitory pathways that block effective antitumour T cell responses.

Ipilimumab is a monoclonal antibody that binds to CTLA-4 and inhibits the interactions with the ligands B7.1 and B7.2, Nivolumab is a monoclonal antibody that targets PD-1. Engagement of PD-1 by its natural ligands, PD-L1 and PD-L2, results in an inhibition of T cell proliferation, survival and cyto-kine secretion. Nivolumab abrogates this interaction between PD-1 and its ligands.

The two antibodies, nivolumab and ipilimumab, do not only target different immune cell receptors, they also regulate distinct inhibitory pathways and have therefore non-overlapping mechanisms of action. Anti-CTLA-4 therapies seem to drive T-cells into tumours, resulting in an increased number of intratumour T-cells and a concomitant increase in IFN-y. This in turn can induce the expression of PD-L1 in the tumour microenvironment, with subsequent inhibition of antitumour T-cell responses, but may also increase the chance of benefit from anti-PD-1 and anti-PD-L1 therapies. A combination treatment with anti-CTLA-4 (e.g. ipili-mumab) plus anti PD-1 (e.g. nivolumab) or anti-PD-L1 antibodies should enable the creation of an immunogenic tumour microenvironment with subsequent clinical benefit for patients.

Nivolumab monotherapy has been approved for the treatment of advanced melanoma (FDA, EMA, and Japan) and previously treated squamous NSCLC (FDA, positive CHMP opin-ion). Nivolumab and ipilimumab improved PFS compared to nivolumab or ipilimumab alone in a study in melanoma (CA209067).

In a randomised open-label phase I/II trial (CheckMate 032), evaluating nivolumab with or without ipilimumab in pretreated SCLC patients with progressive disease and sensitive or refractory to platinum based chemotherapy, based on an interim analysis a response rate of 33% and disease stabilisation in 22% was observed for the combination of nivolumab and ipilimumab compared to 18% response rate and 20% stable disease with nivolumab mono-therapy.

Both, nivolumab monotherapy and nivolumab plus ipilimumab combination treatment were tolerable for the treatment of SCLC, and no new safety profile was identified compared to the profile of nivolumab with or without ipilimumab in other anti-cancer therapies.

Nivolumab plus ipilimumab will be administered as a consolidation treatment after comple-tion of a standard treatment including chemo-radiotherapy and prophylactic cranial irradia-tion (PCI).