Conversion of unresponsiveness to immune checkpoint inhibition by fecal microbiota transplantation in patients with metastatic melanoma: study protocol for a randomized phase Ib/IIa trial

(2022) 22:1366 Borgers et al. BMC Cancer https://doi.org/10.1186/s12885-022-10457-y Open Access STUDY PROTOCOL Conversion of unresponsiveness to immune checkpoint inhibition by fecal microbiota transplantation in patients with metastatic melanoma: study protocol for a randomized phase Ib/IIa trial J. S. W. Borgers1†, F. H. Burgers1†, E. M. Terveer2,3, M. E. van Leerdam4,5, C. M. Korse6, R. Kessels7, C. C. Flohil8, C. U. Blank1, T. N. Schumacher9,10, M. van Dijk11, J. G. E. Henderickx3, J. J. Keller2,5,12, H. W. Verspaget2,13, E. J. Kuijper2,3 and J. B. A. G. Haanen1* Abstract Background: The gut microbiome plays an important role in immune modulation. Specifically, presence or absence of certain gut bacterial taxa has been associated with better antitumor immune responses. Furthermore, in trials using fecal microbiota transplantation (FMT) to treat melanoma patients unresponsive to immune checkpoint inhibitors (ICI), complete responses (CR), partial responses (PR), and durable stable disease (SD) have been observed. However, the underlying mechanism determining which patients will or will not respond and what the optimal FMT composition is, has not been fully elucidated, and a discrepancy in microbial taxa associated with clinical response has been observed between studies. Furthermore, it is unknown whether a change in the microbiome itself, irrespective of its origin, or FMT from ICI responding donors, is required for reversion of ICI-unresponsiveness. To address this, we will transfer microbiota of either ICI responder or nonresponder metastatic melanoma patients via FMT. Methods: In this randomized, double-blinded phase Ib/IIa trial, 24 anti-PD1-refractory patients with advanced stage cutaneous melanoma will receive an FMT from either an ICI responding or nonresponding donor, while continuing anti-PD-1 treatment. Donors will be selected from patients with metastatic melanoma treated with anti-PD-1 therapy. Two patients with a good response (≥ 30% decrease according to RECIST 1.1 within the past 24 months) and two patients with progression (≥ 20% increase according to RECIST 1.1 within the past 3 months) will be selected as ICI responding or nonresponding donors, respectively. The primary endpoint is clinical benefit (SD, PR or CR) at 12 weeks, confirmed on a CT scan at 16 weeks. The secondary endpoint is safety, defined as the occurrence of grade ≥ 3 toxicity. Exploratory endpoints are progression-free survival and changes in the gut microbiome, metabolome, and immune cells. † J. S. W. Borgers and F. H. Burgers shared first authors. *Correspondence: 1 Department of Medical Oncology, Antoni Van Leeuwenhoek, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands Full list of author information is available at the end of the article © The Author(s) 2022. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativeco mmons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Borgers et al. BMC Cancer (2022) 22:1366 Page 2 of 11 Discussion: Transplanting fecal microbiota to restore the patients’ perturbed microbiome has proven successful in several indications. However, less is known about the potential role of FMT to improve antitumor immune response. In this trial, we aim to investigate whether administration of FMT can reverse resistance to anti-PD-1 treatment in patients with advanced stage melanoma, and whether the ICI-responsiveness of the feces donor is associated with its effectiveness. Trial registration: ClinicalTrials.gov: NCT05251389 (registered 22-Feb-2022). Protocol V4.0 (08–02-2022). Keywords: FMT, Gut microbiome, Immunotherapy, Anti-PD-1, Melanoma Background Introduction For patients with advanced stage melanoma, treatment possibilities have increased considerably in the past decade. Since the introduction of immune checkpoint inhibitors (ICI) blocking the inhibitory T cell checkpoints PD-1 and CTLA-4, either sequentially or combined, fiveyear overall survival (OS) rates of up to 50% have been observed in patients with advanced stage melanoma [1]. More recently, a novel combination of anti-LAG-3 plus anti-PD-1 led to improved progression-free survival compared to anti-PD-1 alone [2]. Despite these impressive results, the majority of patients with metastatic melanoma still succumbs to the disease. Ample research of the tumor microenvironment (TME) has revealed several escape mechanisms. However, novel drugs or combinations of drugs to overcome these resistance mechanisms have not yet been approved and major breakthroughs are still lacking. Therefore, other mechanisms to improve the antitumor immune responses are currently being explored. One such a mechanism may be the manipulation of the microbiome of immunotherapy-resistant patients. Preclinical and observational data The first evidence that the gut commensal microbial composition plays an important role in immune responses, including antitumor immunity and responses to ICI, came from preclinical studies. Investigators noticed that C57BL/6 mice derived from different vendors, with known differences in their commensal microbiota, showed differences in spontaneous antitumor immunity upon inoculation of B16 melanoma tumor cells [3]. Fecal microbiota transplantation (FMT) from mice with an increased relative abundance of commensal Bifidobacterium spp. (with a similarity of 99% to B. breve, B. longum, and B. adolescenti) to the other group was associated with delayed tumor growth, to a similar degree as observed upon anti-PD-1 treatment. Combined treatment showed superior activity in these mice [3]. Using 16S ribosomal ribonucleic acid (rRNA) gene amplicon sequencing and shotgun metagenomic sequencing, multiple attempts have been made to identify similar gut microbiome characteristics associated with response to ICI treatment in patients [4–10]. Thus far, several bacterial species, including Akkermansia muciniphila, Bifidobacterium bifidum and adolescentis, Barnesiella intestinihominis, Alistipes species (spp.), Faecalibacterium and othe (...truncated)