Releasing the brakes on CD8+ T cells in the melanoma sentinel lymph node by pre-operative local administration of low-dose anti-CTLA-4 (tremelimumab)

Cutaneous melanoma is the most aggressive type of skin cancer, the incidence of
which has increased rapidly over the past decades. Adjuvant therapy options for
melanoma are still limited and complete surgical excision at an early stage
remains the only curative treatment option. Although of limited therapeutic
value, the sentinel lymph node (SLN) procedure has proven a useful prognostic
tool for the assessment of melanoma relapse and mortality risk. However, the
SLN is of at least equal or perhaps even greater value for the assessment of
immunological interventions for melanoma. The routine SLN procedure as carried
out in the VUmc in early stage melanoma patients provides us with an ideal
platform to test options for pre-operative modulation of SLN immune effector
functions to maximize protection against possible micrometastases. In two
previous Phase II trials carried out at the VUmc, we observed immune-activating
effects in the SLN, following the local intradermal (i.d.) administration of
GM-CSF or the CpG type-B oligodeoxynucleotide around the excision site of the
primary melanoma. Isolation and T cell expansion techniques were developed to
obtain sufficient numbers of immune effector cells from the SLN for functional
monitoring without interfering with standard diagnostic procedures. These
studies provided insight into the different DC subsets present in melanoma SLN
and how these could be targeted through the means of cytokines and/or Toll-like
receptor ligands (TLR-L) in order to (re)activate melanoma-specific CD8+ T
cells. Such local immune modulation strategies may afford local as well as
systemic control of metastatic.The CTL Antigen-4 (CTLA-4) receptor represents a
crucial checkpoint. It is expressed on activated T cells and binds to CD80 and
CD86 on DC with higher avidity than its competitor ligand CD28. In contrast to
CD28, CTLA-4 relays inhibitory signals to the T cell and blocks activating
signals originating from CD28-CD86/CD80 interactions. Numerous pre-clinical and
clinical studies have clearly indicated enhanced anti-tumor efficacy upon
blocking of CTLA-4 and strongly support further implementation of anti-CTLA-4
in immunotherapeutic approaches to the treatment of melanoma. We now propose to
conduct a phase I dose escalation trial of local administration of a single low
dose of anti-CTLA4 (tremelimumab) and to monitor the immunological effects on
the SLN in a correlative study. If this strategy is able to induce a strong
anti-tumor immunity, it would be applicable in the neo-adjuvant treatment
melanoma without the risk of serious toxicity. Hopefully this new approach
could improves the prognosis of high risk melanoma patients.

1) To determine clinical safety and tolerability of local i.d. administration
of a single dose of tremelimumab in clinical stage II melanoma patients
scheduled to undergo a SLN procedure.
2) To ascertain the immunological effects of local i.d. injection of
tremelimumab on the frequency and functionality of tumor-specific T cells and
Tregs -in the SLN and in blood- and on the number and activation state of DC
subsets in the SLN

After resection of primary melanoma and seven days before surgery, clinical
stage II melanoma patients undergoing a triple-technique SLN procedure will be
treated by local i.d. injections, around the excision site of the primary
tumor, of escalating doses of 2, 5, 10 or 20 mg tremelimumab (3 patients per
dose level with an expansion at the optimal dose level with an additional 5
patients). Immunomonitoring of T cells and dendritic cells will be performed on
blood before and 7 days after administration of tremelimumab and on cells
derived from the SLN 7 days after administration of tremelimumab. These results
will also be compared with control patients from previous studies.

After resection of primary melanoma and seven days before surgery, clinical
stage II melanoma patients undergoing a triple-technique SLN procedure will be
treated by local i.d. injections, around the excision site of the primary
tumor, of escalating doses of 2, 5, 10 or 20 mg tremelimumab (3 patients per
dose level with an expansion at the optimal dose level with an additional 5
patients).

As can be seen in the investigator brochure no toxicity was observed in the 1
mg/kg i.v. cohort. Therefore, the low dosage (highest fixed dose of ipilimumab
is 20 mg) used in this trial makes the emergence of toxicity very unlikely.