Could a common antibiotic shrink NF2 skin tumors without surgery?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. Patients must have a confirmed diagnosis of neurofibromatosis 2 by fulfilling National Institute of Health (NIH) criteria or Manchester criteria, or by detection of a causative mutation in the NF2 gene. The NIH criteria include presence of: * Bilateral vestibular schwannomas, OR * First-degree relative with NF2 and EITHER unilateral eighth nerve mass OR * Two of the following: neurofibroma, meningioma, glioma, schwannoma, juvenile posterior subcapsular lenticular opacity. The Manchester criteria include presence of: * Bilateral vestibular schwannomas, OR First-degree relative with NF2 and EITHER unilateral eighth nerve mass OR - Two of the following: neurofibroma, meningioma, glioma, schwannoma, juvenile posterior subcapsular lenticular opacity OR * Unilateral vestibular schwannoma AND any two of: neurofibroma, meningioma, glioma, schwannoma, juvenile posterior subcapsular lenticular opacity, OR * Multiple meningiomas (two or more) AND unilateral vestibular schwannoma OR * Any two of: schwannoma, glioma, neurofibroma, cataract. 2. Patients must have measurable disease, defined as at least one cutaneous/subcutaneous schwannoma with the following qualities: * Maximal tumor diameter \> 0.5 cm to \< 4.0 cm that can be accurately measured by electronic calipers * Up to a maximum of 3 tumors/subject may be injected * Not located on the face 3. Age ≥ 8 years on day 1 of treatment. 4. Life expectancy of greater than 1 year 5. Lansky/Karnofsky performance status ≥ 60 6. Fully recovered from acute toxic effects of any prior chemotherapy, biological modifiers or radiotherapy 7. Any neurologic deficits must be stable for ≥1 week 8. Patient or parent/legal guardian must be able to provide signed informed consent and assent (as applicable for minors) Exclusion Criteria: 1. Allergy to doxycycline or tetracycline 2. Tumors located on the face or major motor nerves 3. Patients currently receiving medical anticancer therapies or who have received medical anticancer therapies within 4 weeks of the start of study drug (including chemotherapy and molecular targeted agents), as these may interfere with the study drug 4. Radiation therapy to a study target tumor within 1 year prior to enrollment, or any radiation therapy within 4 weeks prior to enrollment, as these may interfere with our ability to assess response to study drug 5. Prior treatment with any investigational drug within the preceding 4 weeks, as they may interfere with the study drug 6. Unstable or rapidly progressive disease, including patients who require glucocorticoids for symptomatic control of brain or spinal tumors, as this would represent a high risk for inability to comply with the study requirements 7. Patients who have any severe and/or uncontrolled medical conditions or other conditions that could affect their participation in the study such as: * symptomatic congestive heart failure of New York heart Association Class III or IV * unstable angina pectoris, symptomatic congestive heart failure, myocardial infarction within 6 months of start of study drug, serious uncontrolled cardiac arrhythmia or any other clinically significant cardiac disease * severely impaired lung function as defined as spirometry and DLCO that is 50% of the normal predicted value and/or O2 saturation that is 90% or less at rest on room air * active (acute or chronic) or uncontrolled severe infections liver disease, such as cirrhosis or severe hepatic impairment (Child-Pugh class C) 8. Female patients who are pregnant or breast feeding, or adults of reproductive potential who are not using effective birth control methods. Adequate contraception (oral contraceptives, contraceptive implants, vaginal ring, or intrauterine devices (IUDs)) must be used at the time of injection but does not need to be carried out past the 1st month of observation. 9. History of significant noncompliance with follow-up that would jeopardize the study evaluation. 10. Patients unwilling to or unable to comply with the study protocol.