Phase 3 Gene Therapy for Painful Diabetic Neuropathy

Inclusion Criteria:

1. Age ≥ 18 years to ≤ 75 years

2. Documented history of type I or II diabetes with current treatment control (HbA1c of ≤ 10.0% at Screening) and currently on medication for diabetes (oral, injectable,and/or insulin)

3. No significant changes anticipated in diabetes medication regimen

4. No new symptoms associated with diabetes within the last 3 months prior to studyentry

5. Diagnosis of painful diabetic peripheral neuropathy in both lower extremities

6. Lower extremity pain for at least 6 months

7. Visual analog scale score of ≥ 40 mm at Initial Screening (0 mm = no pain - 100 mmvery severe pain)

8. Symptoms from the Brief Pain Neuropathy Screening is ≤ 5 point difference betweenlegs at Initial Screening

9. The average daily pain intensity score of the Daily Pain and Sleep InterferenceDiary completed after medication wash-out is ≥ 4 with a standard deviation ≤ 2

10. The physical examination component of the Michigan Neuropathy Screening InstrumentScore is ≥ 3 at Screening

11. Subjects on gabapentin (Neurontin), pregabalin (Lyrica), duloxetine (Cymbalta) forpainful Diabetic Peripheral Neuropathy at study entry must be on stable regimen ofthese treatments for at least 3 months prior to study entry

12. If female of childbearing potential, negative urine pregnancy test at screening andusing acceptable method of birth control during the study

Exclusion Criteria:

1. Peripheral neuropathy caused by condition other than diabetes

2. Other pain more severe than neuropathic pain that would prevent assessment ofDiabetic Peripheral Neuropathy

3. Progressive or degenerative neurological disorder

4. Myopathy

5. Inflammatory disorder of the blood vessels (inflammatory angiopathy, such asBuerger's disease)

6. Active infection

7. Chronic inflammatory disease (e.g., Crohn's disease, rheumatoid arthritis)

8. Positive HIV or HTLV at Screening

9. Active Hepatitis B or C as determined by Hepatitis B core antibody (HBcAb), antibodyto Hepatitis B surface antigen (IgG and IgM; HBsAb), Hepatitis B surface antigen (HBsAg), and Hepatitis C antibodies (Anti HCV) at Screening

10. Subjects with known immunosuppression or currently receiving immunosuppressivedrugs, chemotherapy, or radiation therapy

11. Stroke or myocardial infarction within last 3 months

12. Specific laboratory values at Screening including: Hemoglobin < 8.0 g/dL, WBC < 3,000 cells per microliter, platelet count <75,000/mm3, Creatinine > 2.0 mg/dL; ASTand/or ALT > 3 times the upper limit of normal or any other clinically significantlab abnormality which in the opinion of the investigator should be exclusionary

13. Ophthalmologic conditions pertinent to proliferative retinopathy or conditions thatpreclude standard ophthalmologic examination

14. Uncontrolled hypertension defined as sustained systolic blood pressure > 200 mmHg ordiastolic BP > 110 mmHg at Screening

15. Subjects with a recent history (< 5 years) of or new screening finding of malignantneoplasm except basal cell carcinoma or squamous cell carcinoma of the skin (ifexcised and no evidence of recurrence for one year); subjects with family history ofcolon cancer in any first degree relative are excluded unless they have undergone acolonoscopy in the last 12 months with negative findings

16. Use of the following drugs / therapeutics is prohibited. Subjects may participate inthe study if they are willing to discontinue use of these drugs / therapeutics 7days prior to starting the 7 Day Daily Pain and Sleep Interference Diary. Subjectsmust refrain from taking these drugs or undergoing these therapies for the durationof the study

• skeletal muscle relaxants, opioids, benzodiazepines (except for stable bedtimedose),

• capsaicin, local anesthetic creams (except for lidocaine cream prior tointramuscular injection) and patches, isosorbide dinitrate spray,

• transcutaneous electrical nerve stimulation (TENS), acupuncture

17. If not using gabapentin (Neurontin) or pregabalin (Lyrica), subjects must agree notto start these drugs for the first 180 days of the study. Subjects on thesemedications at study entry must maintain a stable dose until Day 180 of the study;

18. If not using duloxetine (Cymbalta), any antidepressants (e.g., amitriptyline andvenlafaxine), any other antiepileptics (e.g., valproic acid, carbamazepine,vigabatrin), subjects must agree not to start these drugs for the first 6 months ofthe study. Subjects on these medications at study entry must maintain a stable dose until Day 180 of the study

19. Subjects requiring > 81 mg daily of acetylsalicylic acid; subjects may be enrolledif willing/able to switch to ≤ 81 mg daily of acetylsalicylic acid or to anothermedication

20. Subjects requiring regular COX-2 inhibitor drug(s) or non-specific COX-1/COX-2inhibiting drugs, or high dose steroids (except inhaled steroids or ocular steroids)subjects may be enrolled if willing/able to undergo medication wash-out prior to thefirst dosing and to refrain from taking these drugs until Day 180 of the study

21. Major psychiatric disorder within the last 180 days that would interfere with studyparticipation

22. Body mass index > 45 kg/m2 at Screening

23. Any lower extremity amputation due to diabetic complications

24. Use of an investigational drug or treatment in past 6 months, or prior participationin any study of Engensis (VM202)

25. Unable or unwilling to give informed consent