SYNTHESIS OF MULTI-EPITOPIC GLYCOPEPTIDE-BASED CANCER VACCINES - Biologically-Responsive Hybrid Biomaterials - page 141

using a resin containing the allylic HYCRON linker with HATU/HOAt coupling
reagents, whereas other amino acids were coupled with HBTU/HOBt. As it was
shown that MUC1 is not suitable to induce a tumor-selective response, the
authors suggested the insertion of a T-helper peptide epitope by fragment
condensation (Figure 5).

OH CO2H

OH

HO

O

O

AcHN

H O

5 HO

O

HO

O

AcHN

N

O O

Y-S-Y-F-P-S-V

N
H

O

G-V-T-S-A-P-D-T-R-P-A-P

spacer O

T- cell epitope =
tetanu s to xin fr agm ent (T TX)

MUC 1 tande m re peat r egion

OH CO 2 H

HO OH

O

O

AcHN

H O

6

HO

O

H O

O

AcH N

N

O O

G-V-T-S-A-P-D-T-R-P-A-P I-S-Q-A-V-H-A-A-H-A-E-I-N-E-A-G-R

N
H

O

spacer

O

OVA 323-339 T helper cell epit ope

M UC1 ta ndem r epeat region

OH C O2H

OH

HO

O

O

AcHN

HO

OH OH

H O H O HO

7 O O O

HO HO HO

O

AcHN AcHN AcHN

N

O O

P-A-H-G-V-T-S-A-P-D-T-R-P-A-P-G-S-T-A-P

N
H

O

I-S-Q-A-V-H-A-A-H-A-E-I-N-E-A-G-R

spacer

O

MU C1 glycop eptid e antigen OVA3 23-3 39 T he lper cell ep itope

Fig. 5. Structure of MUC 1-T helper peptide conjugates.

The resulting resin bound STn-glycododecapeptide from MUC1 was finally
linked by amide coupling to the tetanus toxin (YSYFPSV) containing a
triethylene glycol spacer at the N -terminal end. After final cleavage then
deprotection steps in solution, the full T-helper-spacer-MUC1 glycopeptide 5
was isolated by preparative HPLC in a satisfactory yield (47%) and suitable
purity for immunological assays. Using a similar synthetic strategy, more recent
studies by the same group report on the synthesis of several other constructions
containing up to three STn motifs on a MUC1 peptide conjugated to the
ovalbumin fragment OVA 323-339 as T-helper peptide epitopes 6 - 7 [25-26].