T 1054/06 (Quinoxaline derivatives/AVENTIS PHARMACEUTICALS) 22-09-2009

I. This appeal lies from the decision of the examining division to refuse the European patent application EP-A-98 925 041.0, which was published as WO-A-98/54158.

II. Claim 1 of the refused request reads as follows:

"1. A compound of the formula (i)

FORMULA/TABLE/GRAPHIC

wherein

X is L2Z2

L2 is (CR3aR3b)pZ4-(CR3'aCR3´b)q or ethenyl;

Z2 is

(i) a non-aromatic monocyclic or multicyclic ring system of 3 to 10 carbon atoms (hereinafter referred to as "cycloalkyl");

(ii) a non-aromatic monocyclic or multicyclic ring system containing a carbon-carbon double bond and having 3 to 10 carbon atoms (hereinafter referred

to as "cycloalkenyl");

(iii) a 4- to 10-member monocyclic or multicyclic ring system wherein one or more of the atoms in the ring system is chosen from amongst nitrogen, oxygen

and sulfur (hereinafter referred to as "heterocyclyl"); or

(iv) a 4-to 10-member monocyclic or multicyclic ring system which is partially saturated and wherein one or more of the atoms in the ring system is chosen from amongst nitrogen, oxygen or sulfur (hereinafter referred to as "heterocyclenyl");

any of which is optionally substituted by S1;

Z4 is O, NR4, S, SO, SO2, or a bond;

p and q are independently 0,1,2,3 or 4, and p + q = 1,2,3, or 4 when Z4 is a bond, and p + q = 0, 1, 2, or 3 when Z4 is other than a bond;

R1a and R1b are, independently:

(i) an aliphatic hydrocarbon group which may be branched- or straight-chained, having 1 to 10 carbon atoms, and optionally substituted by S2 (hereinafter

referred to as "alkyl");

(ii) an aromatic carbocyclic radical containing 6 to 10 carbon atoms and optionally substituted by S3 (hereinafter referred to as "aryl");

(iii) a 5- to 10-membered aromatic monocyclic or multicyclic hydrocarbon ring system in which one or more of the carbon atoms in the ring system is

nitrogen, oxygen or sulfur, optionally substituted by S3 (hereinafter referred to as "heteroaryl")

(iv) hydroxy;

(v) H-CO-O- or alkyl-CO-O- (hereinafter referred to as "acyloxy");

(vi) an alkyl-O- group optionally substituted by S4 (hereinafter referred to as "alkoxy");

(vii) a cycloalkyl-O- group optionally substituted by S1 (hereinafter referred to as "cycloalkyloxy");

(viii) a heterocyclyl-O- group optionally substituted by S1 (hereinafter referred to as "heterocyclyloxy");

(ix) a heterocyclyl-C(o)-O- group optionally substituted by S1 (hereinafter referred to as "heterocyclylcarbonyloxy");

(x) an aryl-O- group optionally substituted by S3 (hereinafter referred to as "aryloxy");

(xi) a heteroaryl-O- group optionally substituted by S3 (hereinafter referred to as "heteroaryloxy");

(xii) cyano;

(xiii) R5R6N-; or

(xiv) acylR5N-;

or one of R1a and R1b is hydrogen or halo and the other is alkyl, aryl, heteroaryl, hydroxy, acyloxy, alkoxy, cycloalkyloxy, heterocyclyloxy, heterocyclylcarbonyloxy, aryloxy, heteroaryloxy, cyano, R5R6N- or acylR5N-;

- R1c is hydrogen, alkyl, aryl, heteroaryl, hydroxy, acyloxy, alkoxy, cycloalkyloxy, heterocyclyloxy, aryloxy, heteroaryloxy, halo, cyano, R5R6N- or

acylR5N-;

S1 is alkyl, hydroxy, acyloxy, alkoxy, halo, R5R6N-, acylR5N-, carboxy or R5R6NCO- or a bivalent oxygen (-O-) on two adjacent carbon atoms to form an epoxide;

S2 is alkoxy, halo, carboxy, hydroxy, or R5R6N-;

S3 is hydrogen, hydroxy, halo, alkyl, alkoxy, carboxy, alkoxycarbonyl or Y1Y2NCO-, wherein Y1 and Y2 are independently hydrogen or alkyl;

S4 is amino, alkoxy, carboxy, alkoxycarbonyl, carboxyaryl, carbamoyl or heterocyclyl;

R3a, R3b, R3a´ and R3b´ are independently hydrogen or alkyl;

R4 is hydrogen, alkyl or acyl; and

R5 and R6 are independently hydrogen or alkyl, or R5 and R6 taken together with the nitrogen atom to which they are attached form a heteroaryl group in which

at least one nitrogen atom is present as a ring atom (hereinafter referred to as "azaheterocyclyl");

or an N-oxide thereof, hydrate thereof, solvate thereof, prodrug thereof, or pharmaceutically acceptable salt thereof."

III. The examining division decided that the presence of the expression "prodrugs" in claim 1 contravened the requirements of Articles 83 and 84 EPC. It contended that the definition given in the description for this word was not clear, since in the absence of any further definitions it did not clearly define the scope to be protected. No way of synthesis for the preparation of these prodrugs was mentioned in the description as originally filed and the person skilled in the art did not have any information as to how prepare these compounds. Moreover, a test allowing the person skilled in the art to test these prodrugs was also not disclosed in the description as originally filed. Hence, the person skilled in the art did not know, in the absence of information, which compounds fall under the scope of the claims and which test was to be used to predict whether after metabolisation, a compound will deliver the drug. The mere citation of "Pro-drugs as Novel Delivery systems" and "Bioreversible Carriers in Drug Design" could not be considered as a sufficient disclosure. The examining division found these disclosures as being the equivalent of a "research program" and concluded that the requirements of Article 83 EPC were not fulfilled.

IV. With his statement setting out the grounds of appeal, the appellant maintained the refused request and provided two auxiliary requests and argued that

- the term "prodrugs" was clear and had a well-established meaning in the field of medicinal chemistry. Its scope was also clear, since the person skilled in the art would recognize that any compound outside of the claimed scope but converted in vivo to a compound according to formula (i) of claim 1 was a prodrug of a compound of formula (i).

- based on Dr. Collis' declaration, which referred to citations in the books "Pro-drugs as Novel Delivery systems" and "Bioreversible Carriers in Drug Design", the person skilled in the art would readily recognize whether any particular compound would constitute a "prodrug". He, however, conceded that it was not possible to give an exhaustive and complete list of all possible "prodrugs".

- a reference-back to the decision T 68/85 (OJ EPO 1987, 228) was made in order to point out that not using the term "prodrug" would restrict in an unfair manner the scope of the invention.

V. In its annex to the summons to oral proceedings, the board noted in particular the following:

- due to the limitations carried out in the wording of the claims, the appellant was invited to point out the corresponding passages of the description, which justified such amendments. The appellant's attention was more particularly drawn to the groups L2, Z1 and X.

- the term "prodrug" in view of the documents cited may be understood as compounds which must be chemically transformed within the body to exert its pharmacological or therapeutic action. However, the question is whether this definition enables the person skilled in the art to identify without undue burden the compounds which are covered by the claimed subject-matter or, on the contrary, is simply a result to be achieved (Article 84 EPC). Likewise, the question is whether this definition gives the person skilled in the art sufficient guidance to find without undue burden the prodrugs of the compounds defined in Claim 1 appropriate to treat the mentioned diseases (Article 83 EPC).

The board observes that document (5), namely G L Patrick, "An introduction to Medicinal Chemistry", second edition, pp. 239-250, seems to point out that when designing prodrugs, it is important to ensure that the prodrug is effectively converted to the active drug once it has been absorbed into the blood supply, but it is also important to ensure that any groups cleaved from the molecule are non-toxic (see page 239, bottom). In addition, the appellant should be prepared also to discuss all the information disclosed in the documents cited.

If the board would come to the conclusion that one of the requests on file meets the requirements of Articles 123(2), 84 and 83 EPC, the case would be remitted to the first instance for further prosecution.

VI. With a further letter of 9 July 2009, the appellant withdrew the main and the auxiliary requests 1 and replaced them by a new main request and a new auxiliary request 1. Furthermore, he amended the auxiliary request 2 as filed with his statement setting out his grounds of appeal. He also supported the view that the limitation to X is L2Z2 and Z1 is nitrogen did not contravene Article 123(2) EPC.

VII. The board issued a second communication, in which it gave the appellant the provisional reasons as to why the main and the auxiliary requests 1 and 2 contravened the requirements of Article 123(2) EPC.

VIII. With a fax of 16 July 2009, the appellant, still considering his main request as patentable, maintained it and filed as a precaution a new version of the auxiliary request 1 and a new version of the auxiliary request 2. He also mentioned that he would be prepared to accept either auxiliary request 1 or auxiliary request 2 if the board would confirm the remittal of the case to the first instance for further prosecution.

Claim 1 of this second auxiliary request, which contained fifteen claims, reads as follows:

"1. A compound of the formula (i)

FORMULA/TABLE/GRAPHIC

wherein

X is L2Z2

L2 is (CR3aR3b)pZ4-(CR3'aCR3´b)q or ethenyl;

Z2 is

(i) a non-aromatic monocyclic or multicyclic ring system of 3 to 10 carbon atoms (hereinafter referred to as "cycloalkyl");

(ii) a non-aromatic monocyclic or multicyclic ring system containing a carbon-carbon double bond and having 3 to 10 carbon atoms (hereinafter referred

to as "cycloalkenyl");

(iii) a 4- to 10-member monocyclic or multicyclic ring system wherein one or more of the atoms in the ring system is chosen from amongst nitrogen, oxygen

and sulfur (hereinafter referred to as "heterocyclyl"); or

(iv) a 4-to 10-member monocyclic or multicyclic ring system which is partially saturated and wherein one or more of the atoms in the ring system is chosen from amongst nitrogen, oxygen or sulfur (hereinafter referred to as "heterocyclenyl");

any of which is optionally substituted by S1;

Z4 is O, NR4, S, SO, SO2, or a bond;

p and q are independently 0,1,2,3 or 4, and p + q = 1,2,3, or 4 when Z4 is a bond, and p + q = 0, 1, 2, or 3 when Z4 is other than a bond;

R1a and R1b are, independently:

(i) an aliphatic hydrocarbon group which may be branched- or straight-chained, having 1 to 10 carbon atoms, and optionally substituted by S2 (hereinafter

referred to as "alkyl");

(ii) an aromatic carbocyclic radical containing 6 to 10 carbon atoms and optionally substituted by S3 (hereinafter referred to as "aryl");

(iii) a 5- to 10-membered aromatic monocyclic or multicyclic hydrocarbon ring system in which one or more of the carbon atoms in the ring system is

nitrogen, oxygen or sulfur, optionally substituted by S3 (hereinafter referred to as "heteroaryl")

(iv) hydroxy;

(v) H-CO-O- or alkyl-CO-O- (hereinafter referred to as "acyloxy");

(vi) an alkyl-O- group optionally substituted by S4 (hereinafter referred to as "alkoxy");

(vii) a cycloalkyl-O- group optionally substituted by S1 (hereinafter referred to as "cycloalkyloxy");

(viii) a heterocyclyl-O- group optionally substituted by S1 (hereinafter referred to as "heterocyclyloxy");

(ix) a heterocyclyl-C(o)-O- group optionally substituted by S1 (hereinafter referred to as "heterocyclylcarbonyloxy");

(x) an aryl-O- group optionally substituted by S3 (hereinafter referred to as "aryloxy´);

(xi) a heteroaryl-O- group optionally substituted by S3 (hereinafter referred to as `heteroaryloxy´);

(xii) cyano;

(xiii) R5R6N-; or

(xiv) acylR5N-;

or one of R1a and R1b is hydrogen or halo and the other is alkyl, aryl, heteroaryl, hydroxy, acyloxy, alkoxy, cycloalkyloxy, heterocyclyloxy, heterocyclylcarbonyloxy, aryloxy, heteroaryloxy, cyano, R5R6N- or acylR5N-;

- R1c is hydrogen, alkyl, aryl, heteroaryl, hydroxy, acyloxy, alkoxy, cycloalkyloxy, heterocyclyloxy, aryloxy, heteroaryloxy, halo, cyano, R5R6N- or

acylR5N-;

S1 is alkyl, hydroxy, acyloxy, alkoxy, halo, R5R6N-, acylR5N-, carboxy or R5R6NCO- or a bivalent oxygen (-O-) on two adjacent carbon atoms to form an epoxide;

S2 is alkoxy, halo, carboxy, hydroxy, or R5R6N-;

S3 is hydrogen, hydroxy, halo, alkyl, alkoxy, carboxy, alkoxycarbonyl or Y1Y2NCO-, wherein Y1 and Y2 are independently hydrogen or alkyl;

S4 is amino, alkoxy, carboxy, alkoxycarbonyl, carboxyaryl, carbamoyl or heterocyclyl;

R3a, R3b, R3a´ and R3b´ are independently hydrogen or alkyl;

R4 is hydrogen, alkyl or acyl; and

R5 and R6 are independently hydrogen or alkyl, or R5 and R6 taken together with the nitrogen atom to which they are attached form a heteroaryl group in which

at least one nitrogen atom is present as a ring atom (hereinafter referred to as "azaheterocyclyl");

or an N-oxide thereof, hydrate thereof, solvate thereof, pharmaceutically acceptable salt thereof, or ketal, ester or zwitterionic thereof."

IX. With a fax sent on 17 July 2009, the board gave the appellant its provisional opinion as to the requests on file. The main request and auxiliary request 1 were still considered as contravening the requirements of Article 123(2) EPC but since the auxiliary request 2 was in agreement with these requirements and since the expression "prodrugs" was no longer present in the wording of the claims, the board let the appellant know that it intended to remit the case to the first instance to prosecute examination on the basis of this second auxiliary request. However, due to the presence of the main request and auxiliary request 1, oral proceedings were not cancelled.

X. With a fax dated of 17 July 2009, the appellant withdrew his main request and auxiliary request 1. He expected the oral proceedings to be cancelled and the case remitted to the first instance for further prosecution on the basis of the second auxiliary request (now main request, see point VIII) as filed on 16 July 2009.

XI. The board notified the appellant on 20 July 2009, that the oral proceedings were cancelled.

XII. The appellant requested that the decision under appeal be set aside and that the case be remitted to the first instance for further prosecution on the basis of the set of fifteen claims filed as auxiliary request 2 with letter of 16 July 2009 and now sole and main request.