The goal of this clinical trial is to learn if Longidaze works to treat lower urinary tract symptoms in adult males with benign prostatic hyperplasia. It will also learn about the safety of Longidaze. The main question it aims to answer is:

• Does addition of Longidaze to tamsulosin lower the severity of symptoms assessed by International Prostate Symptom Score?
• What medical problems do participants have under the combined treatment by Longidaze and tamsulosin?

Researchers will compare combined therapy (Longidaze + tamsulosin) with monotherapy (tamsulosin only) to see if the combination works better.

Participants will:

• Take tamsulosin (0.4mg) every day for 130 days
• In combined therapy arm -- make intramuscular injections of Longidaze every 5 days (5 injections); then apply Longidaze rectal suppositories every 3 days (10 applications); then apply Longidaze rectal suppositories every 7 days (10 applications)
• Visit the clinic on day 1, 26±1, 60±1, 130±3 for checkups and tests

Inclusion Criteria:

1. Signed Written Informed Consent Form for participation in the study.
2. Male outpatients aged 40 years or older.
3. Presence of lower urinary tract symptoms due to BPH at least 6 months prior to the screening visit.
4. Symptom severity according to the International Prostate Symptom Score (IPSS) ≥ 8 at the screening visit.
5. Negative urethral smear (PCR) test for chlamydia, gonorrhea, trichomoniasis, mycoplasmosis and ureaplasmosis performed no earlier than 1 month prior to study inclusion.
6. Negative blood test (ELISA) for syphilis performed no earlier than 1 month prior to study inclusion.
7. Maximum urine flow rate (Qmax) based on uroflowmetry results during screening is ≥5 ml/sec; residual urine volume during screening is up to 150 ml.
8. Consent to follow the effective methods of contraception specified in the protocol throughout the study.

Exclusion Criteria:

1. History of hypersensitivity to the study drug, background therapy drug or their components or intolerance thereof.
2. Patients who require or do not wish to stop taking drugs prohibited before or during the study.
3. Contraindications to the study therapy at the time of screening: acute infectious diseases; pulmonary hemorrhage and hemoptysis; fresh vitreous hemorrhage.
4. Hematuria, hematological diseases, oncological diseases, chronic heart failure class III-IV according to the New York Heart Association system, diabetes mellitus, chronic renal failure, hypogonadism in the history.
5. Acute prostatitis at the time of screening and/or within 4 weeks before screening.
6. Symptoms of urinary tract infection at the time of screening and/or within 4 weeks before the screening visit.
7. Need for planned surgical treatment of BPH and/or any other concomitant disease within 5 months from the screening visit.
8. History of prostatectomy, transurethral resection and/or other surgical interventions on the prostate gland, bladder or pelvic organs.
9. Neurogenic dysfunction of the bladder, congenital anomalies of the genitourinary system, sclerosis of the bladder neck, bladder diverticula, urolithiasis, bladder cancer or other bladder diseases in the medical history.
10. History of urethral stricture.
11. History of spinal injury.
12. Prostate-specific antigen (PSA) level >4 ng/ml at the screening visit or according to laboratory tests performed no more than 4 weeks before inclusion in the study.
13. History of acute urinary retention.
14. Use of any antibacterial drugs (except topical drugs) within 2 months before the screening visit.
15. Use of any medications for the treatment of LUTS/BPH before the study, including herbal preparations containing extracts of Serenoa repens and Pygeum Africanum.
16. History of orthostatic hypotension.
17. Patients with significant liver dysfunction at the screening visit: total bilirubin >2 ULN, albumin <35 g/L, prothrombin time >3 ULN.
18. Patients with significant renal dysfunction at the screening visit (blood creatinine >2 ULN), and / or patients on dialysis and / or patients with a history of kidney transplant.
19. The patient is scheduled for cataract or glaucoma surgery within 5 months after screening.
20. The presence of sexually transmitted diseases at the time of screening.
21. Patients with positive blood test results for HIV and/or hepatitis B and/or hepatitis C, performed no earlier than 1 month before the screening visit, or at the screening.
22. Decompensated diabetes mellitus (blood glucose and/or HbAc1 grade 3 or higher according to the used CTCAE 4.03 classifier);
23. Severe CNS diseases, including a history of seizures or conditions that may lead to their development; stroke or transient ischemic attack within 12 months before screening; traumatic brain injury or cases of loss of consciousness within 12 months before screening; brain tumor
24. Patients with mental disorders such as psychosis, manic-depressive disorders, chronic depression.
25. Acute or chronic gastric and/or duodenal ulcer at the time of screening.
26. History of alcoholism, drug addiction, drug abuse.
27. Participation in other interventional clinical trials of drugs less than 90 days before the screening visit.
28. Any conditions that, in the opinion of the Investigator, may interfere with the patients participation in the study, compliance with the procedures, or be contrary to his interests, as well as affect the results of the study.
29. Employees of the study center or the Sponsor company, their family members or subjects in dependent relationships.