A therapeutic drug and targeting conjugate useful in anti-neoplastic therapies comprising: (a) a ligand which comprises an immunoglobulin or functional fragment thereof which targets human oncofetal protein 5T4, the ligand having bound thereto m 5 of polymeric scaffolds of (b), wherein m 5 is one to ten; (b) a polymeric scaffold comprising poly(1-hydroxymethylethylene hydroxymethyl-formal) which has a molecular weight ranging from 2 kDa to 40 kDa, wherein the polymeric scaffold comprises randomly arranged monomeric units m, m 1, m 2, m3a and m 3b, defined as follows: (i) m 3a: wherein m 3a is absent or 1 to 17 monomeric m 3a units are present in the polymer scaffold, and in each unit, X a and X b are independently selected from one is H and the other is a maleimido blocking moiety, or X a and X b, together with the carbon atoms to which they are attached form a carbon-carbon double bond; (ii) m 3b, wherein the sulfide bond forms the point of attachment to the ligand, and wherein 1 to 8 monomer m 3b units are present in the polymeric scaffold, provided that the sum of m 3a and m 3b is 1 to 18, and wherein the sulfur atom is part of the ligand, (iii) m:, wherein 1 to 300 monomer m units are present in the polymeric scaffold; (iv) m 1: wherein 1 to 140 monomeric m 1 units are present in the polymer scaffold; (v): m 2: wherein 1 to 40 monomeric m 2 units are present in the polymer scaffold; wherein in each of the monomeric units m, m 1, m 2, m 3a, and m 3b, X is CH 2, O or NH, the sum of m, m 1, m 2, m 3a, and m 3b ranges from 15 to 300, and wherein each occurrence of D independently is a therapeutic agent having a molecular weight of ≤ 5kDa, and the between D and the carbonyl group denotes direct or indirect attachment of D to the carbonyl group. (a) a ligand which comprises an immunoglobulin or functional fragment thereof which targets human oncofetal protein 5T4, the ligand having bound thereto m 5 of polymeric scaffolds of (b), wherein m 5 is one to ten; (b) a polymeric scaffold comprising poly(1-hydroxymethylethylene hydroxymethyl-formal) which has a molecular weight ranging from 2 kDa to 40 kDa, wherein the polymeric scaffold comprises randomly arranged monomeric units m, m 1, m 2, m3a and m 3b, defined as follows: (i) m 3a: wherein m 3a is absent or 1 to 17 monomeric m 3a units are present in the polymer scaffold, and in each unit, X a and X b are independently selected from one is H and the other is a maleimido blocking moiety, or X a and X b, together with the carbon atoms to which they are attached form a carbon-carbon double bond; (ii) m 3b, wherein the sulfide bond forms the point of attachment to the ligand, and wherein 1 to 8 monomer m 3b units are present in the polymeric scaffold, provided that the sum of m 3a and m 3b is 1 to 18, and wherein the sulfur atom is part of the ligand, (iii) m:, wherein 1 to 300 monomer m units are present in the polymeric scaffold; (iv) m 1: wherein 1 to 140 monomeric m 1 units are present in the polymer scaffold; (v): m 2: wherein 1 to 40 monomeric m 2 units are present in the polymer scaffold; wherein in each of the monomeric units m, m 1, m 2, m 3a, and m 3b, X is CH 2, O or NH, the sum of m, m 1, m 2, m 3a, and m 3b ranges from 15 to 300, and wherein each occurrence of D independently is a therapeutic agent having a molecular weight of ≤ 5kDa, and the between D and the carbonyl group denotes direct or indirect attachment of D to the carbonyl group. (i) m 3a: wherein m 3a is absent or 1 to 17 monomeric m 3a units are present in the polymer scaffold, and in each unit, X a and X b are independently selected from one is H and the other is a maleimido blocking moiety, or X a and X b, together with the carbon atoms to which they are attached form a carbon-carbon double bond; (ii) m 3b, wherein the sulfide bond forms the point of attachment to the ligand, and wherein 1 to 8 monomer m 3b units are present in the polymeric scaffold, provided that the sum of m 3a and m 3b is 1 to 18, and wherein the sulfur atom is part of the ligand, (iii) m:, wherein 1 to 300 monomer m units are present in the polymeric scaffold; (iv) m 1: wherein 1 to 140 monomeric m 1 units are present in the polymer scaffold; (v): m 2: wherein 1 to 40 monomeric m 2 units are present in the polymer scaffold; wherein in each of the monomeric units m, m 1, m 2, m 3a, and m 3b, X is CH 2, O or NH, the sum of m, m 1, m 2, m 3a, and m 3b ranges from 15 to 300, and wherein