MART-1 antigen(NCI)

Immunotherapy offers a promising novel approach for the treatment of cancer and both adoptive T-cell transfer and immune modulation lead to regression of advanced melanoma. However, the potential synergy between these two strategies remains unclear.

We investigated in 12 patients with advanced stage IV melanoma the effect of multiple MART-1 analog peptide vaccinations with (n = 6) or without (n = 6) IMP321 (LAG-3Ig fusion protein) as an adjuvant in combination with lymphodepleting chemotherapy and adoptive transfer of autologous PBMCs at day (D) 0 (Trial registration No: NCT00324623). All patients were selected on the basis of ex vivo detectable MART-1-specific CD8 T-cell responses and immunized at D0, 8, 15, 22, 28, 52, and 74 post-reinfusion.

After immunization, a significant expansion of MART-1-specific CD8 T cells was measured in 83% (n = 5/6) and 17% (n = 1/6) of patients from the IMP321 and control groups, respectively (P < 0.02). Compared to the control group, the mean fold increase of MART-1-specific CD8 T cells in the IMP321 group was respectively >2-, >4- and >6-fold higher at D15, D30 and D60 (P < 0.02). Long-lasting MART-1-specific CD8 T-cell responses were significantly associated with IMP321 (P < 0.02). At the peak of the response, MART-1-specific CD8 T cells contained higher proportions of effector (CCR7⁻ CD45RA⁺/⁻) cells in the IMP321 group (P < 0.02) and showed no sign of exhaustion (i.e. were mostly PD1⁻CD160⁻TIM3⁻LAG3⁻2B4⁺/⁻). Moreover, IMP321 was associated with a significantly reduced expansion of regulatory T cells (P < 0.04); consistently, we observed a negative correlation between the relative expansion of MART-1-specific CD8 T cells and of regulatory T cells. Finally, although there were no confirmed responses as per RECIST criteria, a transient, 30-day partial response was observed in a patient from the IMP321 group.

Vaccination with IMP321 as an adjuvant in combination with lymphodepleting chemotherapy and adoptive transfer of autologous PBMCs induced more robust and durable cellular antitumor immune responses, supporting further development of IMP321 as an adjuvant for future immunotherapeutic strategies.

In this short note we report on the shelf-life stability of pDERMATT (plasmid DNA encoding recombinant MART-1 and tetanus toxin fragment-c) 2mg lyophilized powder for reconstitution for intradermal administration, used in an in-house, investigator-initiated clinical phase I study. pDERMATT was stored at 25°C/60% relative humidity (6 months), 2-8°C (24 months), and -20°C (66 months) in the dark and analyzed at several timepoints during the conduct of the clinical study for appearance, identity, purity (plasmid topology), content and residual water content. pDERMATT appeared stable at all storage conditions for the periods tested which, although patient inclusion in the study was significantly delayed, ensured the clinical supply needs. This study shows that lyophilization is an useful tool to preserve the quality of the pDNA and can prevent the need for costly and time-consuming additional manufacture of drug product in case of study delays, not uncommon at the early stage of drug development. To our knowledge, this is the first study reporting shelf life stability of a pDNA formulation for more than 5 years.