Longitudinal analysis of tumor-specific T-cel immunity in irresectable stage IIIc and stage IV melanoma patients

Melanoma-specific T cell immunity
There is now widespread evidence that tumor-specific T cell responses can
contribute to the control of melanoma. As an example, treatment of patients
with ipilimumab (an anti-CTLA4 antibody) has shown a survival benefit in
patients with metastatic disease. Likewise, treatment of patients with
metastatic melanoma with ex vivo expanded tumor-infiltrating lymphocytes has
been shown to result in a high response rate in two different centers.
At the same time, little is known about the longitudinal development of
melanoma-specific T cell immunity upon immunotherapeutic treatment. Does the
breadth or strength of the therapy-induced T cell response predict clinical
course? Does reactivity against certain tumor-associated antigens correlate
with tumor regression or with treatment-induced autoimmune disease (e.g.
vitiligo). Better knowledge on the development of melanoma-specific T cell
responses both in peripheral blood and at the tumor site is likely to offer
leads for early monitoring of treatment response and for the development of
more targeted immunotherapies.
Furthermore, it has been postulated that also other therapeutic strategies that
have been developed or are currently in development for melanoma, may
potentially exert their effect in part through the induction of a
melanoma-specific T cell response. As a specific example, the release of
melanoma-associated antigens upon inhibition of BRAF may promote the induction
of T cell responses against these antigens. At present, no data are available
on the relationship between treatment of melanoma with these types of drugs and
the development of tumor-specific T cell responses, either in peripheral blood
or at the tumor site.

• To study the effect of treatment (e.g. anti-CTLA4, BRAF inhibition, TIL
therapy) on the size and diversity of melanoma-specific T cell populations as
measured by MHC tetramer technology and antigen-specific cytokine production.

• To examine treatment induced alterations in the immune infiltrates present
within biopsies.

In total 50-100 patients with proven stage irresectable IIIc or stage IV
melanoma can be enrolled in this study.

All patients will be informed about this study consisting of two parts: 1) To
allow peripheral blood sampling for longitudinal analysis of melanoma-reactive
immune responses and 2) To allow tissue collection through tumor biopsies prior
to and during treatment. Patients will be asked to sign for each part of the
study a separate signature form.
After having signed the ICF, a peripheral blood sample (100 ml) will be drawn
prior to and during treatment, and isolated peripheral blood mononuclear cells
will be frozen immediately for research purposes. If a metastasis is easily
accessible and the patient signed the informed consent for tumor biopsies, a
tumor biopsy will be taken before treatment and during therapy.

Sampling of blood and tumor tissue during therapy will be partly dependent on
the type of treatment. For patients treated with standard chemotherapy (DTIC or
temozolomide), blood and tumor tissue sampling will be done after 2 courses
(coinciding with response evaluation).
Blood sampling of patients treated with targeted agents (incl.
BRAF/MEK/PI3K/c-KIT inhibitors) will be done after one course (3-4 weeks of
treatment) and at the moment of response evaluation (blood and tumor tissue).
Blood and tumor tissue sampling of patients on immune activating agents (incl.
anti-CTLA4, anti-PD-1, anti-PD-L1, anti-CD40 mAb etc.) will be done at 3 months
after initiation of treatment (coinciding with response evaluation).

The idea behind these different time points for follow-up samplings is based on
the mode of action of the drug and the knowledge or expectation of the time to
response. Ipilimumab, an immunotherapy-based treatment, results in rather slow
response, whereas the novel targeted agents such as PLX4032, a potent BRAF
V600E inhibitor, sometimes can give clinical responses after a few days of
treatment. In order not to miss the peak of the immune response, the time
points need to be different for the various drugs.

With regard tot blood sampling low burden and risks: hematoma may occur.
With regard to biopsies: hematoma, bleeding and pain. However, only biopsies
will be taken of easily accesible areas so the burden and risks will be
minimalized.