g. DC-LAMP-modified mRNA is used – also class II epitopes. In addition, there is the potential to include functional molecules selleck to program a next generation of “designer” DC. We are, for example, currently testing in a comparative trial “GM-CSF-IL-4” MoDC transfected with mRNA (but after rather than before maturation) coding for three antigenswith
or without an E/L selectin fusion molecule, designed to bring about migration of DC upon i.v. injection from the blood to the lymph nodes and, thereby, achieve stronger T-cell responses with a more diversified homing pattern 84. This would be a major advantage because limited migration even of mature DC from skin injection sites to draining lymph nodes remains a major
limitation, notably as intranodal injection has proven unreliable 85 and pre-conditioning of the injection site in contrast to mice does not enhance DC migration in man (de Vries, personal communication). Interestingly, in our current trial intravenous (but not intracutaneous) injection of DC led to some cases of clinical regressions, and should thus be explored despite a previous comparative trial pointing to the inferiority Maraviroc cell line of the i.v. route 45. We are also exploring DC transfected after maturation with an optimized CD40L mRNA, which results in DC that induce highly proliferative, inflammatory CTL in vitro63, 64. Within the DC-THERA Network of Excellence (www.dc–thera.org), another novel “designer” DC type is currently being compared to other DC, the so-called Tri-Mix DC (generated by transfecting immature GM-CSF+IL-4 DC with mRNA coding for CD70, CD40L, and a constitutively
active TLR4) 86. There are many other possibilities to enhance the stimulatory capacity of DC for T or also NK cells, either by introducing other advantageous molecules via mRNA or silencing inhibitory ones by siRNA transfection (e.g. SOCS1) 87. Loading DC with Clomifene dying tumor cells has proven promising in clinical trials 88, particularly with autologous tumor cells and “only” cocktail-matured DC 89, 90. The workup of the patients treated by C.W. Schmidt’s group 89, 90 using a laborious yet highly informative strategy 4 has shown that the vaccine-induced immune responses are dominated by highly individualized responses to shared and neoantigens generated by somatic point mutations (Thomas Wölfel, personal communication) in congruence with previous observations in select melanoma patients 3, 4. The mRNA transfection approach allows for exploring the total antigenic repertoire of tumors without limitations imposed by availability of tumor tissue, as even a few cells can provide sufficient amounts of mRNA for PCR amplification 81. An alternative approach yet to be tested is to take advantage of the increasing knowledge on the cancer genomes, and to use mRNA-transfected DC to specifically target oncogenic driver mutations 91.