BIOMARKER FOR SMALL CELL LUNG CANCER THERAPY

1 . A TLR-9 agonist, preferably Lefitolimod, for use in treating small cell lung cancer (SCLC) in a subject in need thereof, wherein the subject to be treated has one or more of the following characteristics:

i. a ratio of activated B cells with respect to the total number of CD19 positive cells of less than or equal to 20%, preferably of less than or equal to 18%, more preferably of less than or equal to 17%, most preferably less than or equal to 15.4%, and/or

ii. a diagnosed chronic obstructive pulmonary disease (COPD).

2 . The TLR-9 agonist for use according to claim 1 , wherein the activated B cells are CD86 positive.

3 . The TLR-9 agonist for use according to claim 1 or 2 , wherein the SCLC is limited SCLC or extensive SCLC, preferably extensive SCLC.

4 . The TLR-9 agonist for use according to any of the preceding claims, wherein the subject has received a first cancer treatment before treatment with the TLR-9 agonist, in particular a platinum-based chemotherapeutic.

5 . The TLR-9 agonist for use according to any of the preceding claims, wherein the TLR-9 agonist is used in a switch maintenance therapy.

6 . The TLR-9 agonist for use according to any of the preceding claims, wherein the TLR-9 agonist, preferably Lefitolimod, is administered twice a week as switch maintenance therapy in a subject with extensive SCLC and wherein the subject achieved at least a partial response following first-line therapy with a platinum-based chemotherapeutic.

7 . The TLR-9 agonist for use according to any of the preceding claims, wherein the TLR-9 agonist comprises a polydeoxyribonucleotide comprising at least one unmethylated CG dinucleotide, and wherein the at least one CG dinucleotide is part of a sequence N 1 N 2 CGN 3 N 4 , wherein N 1 N 2 is AA, TT, GG, GT, GA or AT and N 3 N 4 is CT, TT, TC, TG or GG and C is deoxycytidine, G is deoxyguanosine, A is deoxyadenosine, and T is deoxythymidine.

8 . The TLR-9 agonist for use according to claim 7 , wherein the polydeoxyribonucleotide comprises at least one nucleotide in L-configuration.

9 . The TLR-9 agonist for use according to claim 7 or 8 , wherein the polydeoxyribonucleotide comprises a double-stranded stem and two single-stranded loops and forms the shape of a dumbbell.

10 . The TLR-9 agonist for use according to claim 9 , wherein the polydeoxyribonucleotide is covalently closed.

11 . The TLR-9 agonist for use according to claim 9 or 10 , wherein the at least one CG dinucleotide is located in one or each of the single-stranded loops.

12 . The TLR-9 agonist for use according to any of claims 9 to 11 , wherein the TLR-9 agonist consists of the sequence of SEQ ID NO: 3.

13 . Method for predicting, whether a subject suffering from SCLC will respond to treatment with a TLR-9 agonist by determining before treatment with the TLR-9 agonist

i. a ratio of activated B cells with respect to the total number of CD19 positive cells, and/or

ii. whether the subject has been diagnosed with COPD.

14 . Method for discriminating among subjects suffering from SCLC between a responder and a non-responder to treatment with a TLR-9 agonist by determining before treatment with the TLR-9 agonist

i. a ratio of activated B cells with respect to the total number of CD19 positive cells, and/or

ii. whether the subject has been diagnosed with COPD.

15 . The method according to claim 14 , wherein the responder has a better overall survival (OS) than the non-responder.

16 . A pharmaceutical composition comprising 1 mg/ml to 30 mg/ml, preferably 10 mg/ml to 20 mg/ml, more preferably 15 mg/ml of Lefitolimod in PBS for use in treating SCLC, wherein the PBS has a pH of pH 6 to 8, in particular 7.2 to 7.6, and comprises

6 mg/ml to 12 mg/ml, preferably 8.0 mg/ml of sodium chloride,

0.1 mg/ml to 0.3 mg/ml, preferably 0.2 mg/ml of potassium chloride

0.1 mg/ml to 0.3 mg/ml, preferably 0.2 mg/ml of potassium dihydrogen phosphate and

1.0 mg/ml to 1.5 mg/ml, preferably 1.15 mg/ml of disodium hydrogen phosphate.

17 . An activated B cell for use as a biomarker for predicting a response to treatment with a TLR-9 agonist, preferably Lefitolimod, in a subject suffering from cancer, in particular from SCLC.