BACKGROUND Pembrolizumab is a potent humanized immunoglobulin G4 (IgG4) monoclonal antibody
(mAb) with high specificity of binding to the programmed cell death 1 (PD 1) receptor, thus
inhibiting its interaction with programmed cell death ligand 1 (PD-L1) and programmed cell
death ligand 2 (PD-L2). Based on preclinical in vitro data, pembrolizumab has high affinity
and potent receptor blocking activity for PD 1. Pembrolizumab has an acceptable preclinical
safety profile and is in clinical development as an intravenous (IV) immunotherapy for
advanced malignancies. Keytruda® (pembrolizumab) is indicated for the treatment of patients
across a number of indications because of its mechanism of action to bind the PD-1 receptor
on the T cell. For more details on specific indications refer to the Investigator brochure
(IB).
Enfortumab Vedotin (EV) is an ADC comprised of a fully human anti-Nectin-4 IgG1 kappa mAb
conjugated to the small molecule microtubule disrupting agent, MMAE, via a protease cleavable
maleimidocaproyl vc linker. Conjugation takes place on cysteine residues that comprise the
interchain disulfide bonds of the antibody to yield a product with a drug to antibody ratio
of approximately 3:8.
EV binds to the V domain of Nectin-4 protein. In the presumed mechanism of action, the drug
binds to the Nectin-4 protein on the cell surface and is internalized, causing proteolytic
cleavage of the vc linker and intracellular release of MMAE. Free MMAE subsequently disrupts
tubulin polymerization and leads to mitotic arrest.
PHARMACEUTICAL AND THERAPEUTIC BACKGROUND. Pembrolizumab. The importance of intact immune surveillance function in controlling outgrowth
of neoplastic transformations has been known for decades. Accumulating evidence shows a
correlation between tumor-infiltrating lymphocytes in cancer tissue and favorable prognosis
in various malignancies. In particular, the presence of CD8+ T-cells and the ratio of CD8+
effector T cells/FoxP3+ regulatory T-cells (T-regs) correlates with improved prognosis and
long-term survival in solid malignancies, such as ovarian, colorectal, and pancreatic cancer;
hepatocellular carcinoma; malignant melanoma; and renal cell carcinoma. Tumor-infiltrating
lymphocytes can be expanded ex vivo and reinfused, inducing durable objective tumor responses
in cancers such as melanoma.
The PD-1 receptor-ligand interaction is a major pathway hijacked by tumors to suppress immune
control. The normal function of PD-1, expressed on the cell surface of activated T cells
under healthy conditions, is to down-modulate unwanted or excessive immune responses,
including autoimmune reactions. PD-1 (encoded by the gene Pdcd1) is an immunoglobulin (Ig)
superfamily member related to cluster of differentiation 28 (CD28) and cytotoxic
T-lymphocyte-associated protein 4 (CTLA-4) that has been shown to negatively regulate antigen
receptor signaling upon engagement of its ligands (PD L1 and/or PD-L2).
The structure of murine PD-1 has been resolved. PD-1 and its family members are type I
transmembrane glycoproteins containing an Ig-variable-type (IgV type) domain responsible for
ligand binding and a cytoplasmic tail responsible for the binding of signaling molecules. The
cytoplasmic tail of PD-1 contains 2 tyrosine-based signaling motifs, an immunoreceptor
tyrosine-based inhibition motif, and an immunoreceptor tyrosine-based switch motif. Following
T-cell stimulation, PD-1 recruits the tyrosine phosphatases, SHP-1 and SHP-2, to the
immunoreceptor tyrosine-based switch motif within its cytoplasmic tail, leading to the
dephosphorylation of effector molecules such as CD3 zeta (CD3ζ), protein kinase C-theta
(PKCθ), and zeta-chain-associated protein kinase (ZAP70), which are involved in the CD3
T-cell signaling cascade. The mechanism by which PD-1 down-modulates T cell responses is
similar to, but distinct from, that of CTLA-4, because both molecules regulate an overlapping
set of signaling proteins. As a consequence, the PD 1/PD-L1 pathway is an attractive target
for therapeutic intervention in Collecting Duct Carcinoma and Renal Medullary Carcinoma.
Enfortumab Vedotin Nectin-4 is a 66 kDa type I transmembrane protein that belongs to the
Nectin family of adhesion molecules. It is composed of an ECD containing 3 Ig-like
subdomains, a transmembrane helix, and an intracellular region. Nectins are thought to
mediate Ca2+-independent cell-cell adhesion via both homophilic and heterophilic trans-
interactions at adherens junctions where they can recruit cadherins and modulate cytoskeletal
rearrangements. Sequence identity of Nectin-4 to other Nectin family members is low and
ranges from 25% to 30% in the ECD.
The 3 Ig-like subdomains in the ECD of Nectin-4 are designated V, C1, and C2. The C1 domain
is responsible for cisplatin-interaction (homodimerization), while V domains of most Nectin
molecules contribute to trans-interaction and cell-cell adhesion.
Nectin-4 was originally identified by bioinformatics and cloned from human trachea. In
humans, Nectin-4 is normally expressed in keratinocytes of the skin, sweat glands, hair
follicles, transitional epithelium of the bladder, salivary gland ducts, esophagus, breast,
and stomach. Nectin-4 was identified as markedly upregulated in urothelial carcinoma using
suppression subtractive hybridization on a pool of urothelial carcinoma specimens.
Immunohistochemical characterization of expression in multiple tumor specimens demonstrated
high levels of Nectin-4 in bladder, breast, pancreatic, lung, ovarian and other cancers.
Enfortumab Vedotin in Combination with Pembrolizumab. Combining PD-1/PD-L1 inhibitors with a
novel therapy, such as EV, may improve patient outcomes. Data from preclinical studies of
brentuximab vedotin (a CD30-directed ADC comprising the same linker and MMAE payload as EV),
shows potential to induce ICD, antigen presentation, and tumor immune infiltration. These
results suggest that the effects are due to MMAE. Treatment with brentuximab vedotin in vitro
and in preclinical models has been shown to induce hallmarks of ICD. ICD is characterized by
induction of the endoplasmic reticulum stress response and subsequent surface presentation of
DAMPs immune stimulatory molecules. These DAMPs induce innate immune migration and activation
into the tumor microenvironment.
Based on the potential enhancement of immune response, it is hypothesized that combining EV
with pembrolizumab will result in improved response leading to prolonged PFS and OS in
patients with Collecting Duct Carcinoma and Renal Medullary Carcinoma with minimal
overlapping toxicities between the 2 agents.
RATIONALE FOR THE TRIAL AND SELECTED POPULATION Non-clear cell renal cell carcinomas (nccRCC)
comprise several rare and poorly described diseases. Among them, Renal medullary carcinoma
(RMNC) represents less than 0,5% and Collecting Duct Carcinoma (CDC) represents 1% of all
renal cell carcinomas. Both are characterized by an aggressive clinical behaviour and a
particular poor prognosis. Both tumors are under-represented in prospective randomized trials
predominantly including clear-cell histotype. Thus, a standard of treatment for these rare
and aggressive histologies has not been defined yet. Based on the data of a small phase II
study with responses of 23%, the more used first line therapy in both cases is a
platinum-based cytotoxic chemotherapy that has the ability to control the disease but only
for a limited time. More recently, the prospective BONSAI trial met its primary endpoint
showing encouraging efficacy of cabozantinib in first line with an objective response (ORR)
of 35% in 25 patients with metastatic CDC (mCDC). Immune-checkpoint inhibitors (ICI) such as
Pembrolizumab in combination with Tyrosine Kinase Inhibitors are now recommended as
standard-of-care options for clear-cell renal cell carcinoma due to the relevant results in
term of antitumor activity and Overall Survival (OS). Cases of excellent response to ICI are
reported in literature also in previously treated mCDC patients. Enfortumab Vedotin showed
encouraging activity in different tumour types and when combined with pembrolizumab showed
relevant results in term of ORR and PFS. More recently, the combination of EV and
pembrolizumab in the EV-103/KEYNOTE-869 (NCT03288545) study has demonstrated dramatic
improvement in ORR in cisplatin- ineligible patients with locally advanced and metastatic
urothelial carcinoma, with a preliminary ORR of 73% (95% CI: 58, 85) regardless of PD-L1
expression level.
Due to the mechanism of action of Enfortumab Vedotin, the expression of NECTIN-4 in CDC is
under analysis in the CICERONE trial (NCT05372302). Unpublished results from this trial,
state that NECTIN-4 is expressed in 30% of CDC tissue. Furthermore, biology of CDC and of
Urothelial Carcinoma is similar, and this support the expression of NECTIN-4 in this orphan
disease and the activity of EV.
Based on the encouraging data regarding the use of ICI in clear cell renal cell carcinoma,
the investigators hypothesize that in these histotypes it may be useful to evaluate in more
depth the action of drugs that act on the immune system in combination with Antibody-Drug
Conjugate (ADC).
PLANNED EXPLORATORY BIOMARKER RESEARCH Analysis on biomarkers is exploratory by nature and
will be performed retrospectively after the main study analysis is completed. Tissue
assessments will include the identification of somatic mutations in CDC and the assessment of
the mutational load by focused exome analysis, as well as the identification of transcript
fusions by RNA sequencing.
Plasma and viable peripheral blood mononuclear cell (PBMC) will be isolated and stored frozen
for subsequent analysis. PBMC will be studied for immune cell profile by multicolor
cytofluorimetry (including frequency and activation state of antitumor and immunosuppressive
cell subsets of both innate and adaptive immunity), associated with gene-expression profiling
and Cibersort analysis for assessing the activation state of the immune cell subsets.