8-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

Date of Report (Date of earliest event reported): October 26, 2004

SONTRA MEDICAL CORPORATION

(Exact Name of Registrant as Specified in its Charter)

Minnesota	000-23017	41-1649949
(State or Other Jurisdiction of Incorporation)	(Commission File Number)	(IRS Employer Identification No.)

10 Forge Parkway

Franklin, Massachusetts 02038

(Address of Principal Executive Offices) (Zip Code)

(508) 553-8850

(Registrant’s telephone number, including area code)

Not Applicable

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

¨ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

¨ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

¨ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

¨ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 8.01 Other Events

On October 26, 2004, Sontra Medical Corporation (the “Registrant”) announced initial human clinical results from a twenty patient study that evaluated the immune response induced by using the Registrant’s SonoPrep^® skin permeation device to facilitate the transdermal delivery of the antigenic proteins, tetanus toxoid and candida albicans (yeast).

A copy of the press release issued by the Registrant concerning the foregoing is filed herewith as Exhibit 99.1 and is incorporated herein by reference.

On November 1, 2004, the Registrant announced that clinical results presented at the Diabetes Technology Meeting held in October in Philadelphia PA, demonstrate that its continuous non-invasive glucose monitoring system, being developed in collaboration with Bayer Diagnostics, reliably detected real-time changes in the blood glucose levels of patients with diabetes.

A copy of the press release issued by the Registrant concerning the foregoing is filed herewith as Exhibit 99.2 and is incorporated herein by reference. A copy of the clinical data and results presented at the Diabetes Technology Meeting on October 28, 2004 is filed herewith as Exhibit 99.3 and is incorporated herein by reference.

Item 9.01 Financial Statements and Exhibits

(c) Exhibits

The following exhibits are filed with this Form 8-K:

99.1	Press Release of the Registrant, dated October 26, 2004.
99.2	Press Release of the Registrant, dated November 1, 2004.
99.3	Continuous Transdermal Glucose Monitoring Clinical Data and Results, presented October 28, 2004.

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

	Sontra Medical Corporation
	By:	/s/ Sean F. Moran
Date: November 2, 2004		Sean F. Moran
		Chief Financial Officer
		(Principal Financial and Accounting Officer)

EXHIBIT INDEX

Exhibit No.	Description
99.1	Press Release of the Registrant, dated October 26, 2004.
99.2	Press Release of the Registrant, dated November 1, 2004.
99.3	Continuous Transdermal Glucose Monitoring Clinical Data and Results, presented October 28, 2004.

EX-99.1

EXHIBIT 99.1

Sontra Announces Promising Initial Human Clinical Results from Transdermal Vaccination Study

SonoPrep Ultrasonic Skin Permeation Device Facilitates Delivery of Antigenic Proteins

FRANKLIN, Mass., October 26, 2004 — Sontra Medical Corporation (Nasdaq SC: SONT) announced today promising initial human clinical results from a twenty patient study conducted by Daniel H. Libraty, M.D. at the University of Massachusetts Medical School that evaluated the immune response induced by using the SonoPrep skin permeation device to facilitate the transdermal delivery of the antigenic proteins, tetanus toxoid and candida albicans (yeast).

In this study, ten patients in the treatment group first received a fast (10-30 seconds) SonoPrep skin pretreatment on their forearm creating an imperceptible window for drug delivery through the skin. Then the antigenic proteins, tetanus toxoid and candida albicans were applied topically to the treated skin sites. A ten-patient control group received the standard intradermal injection of the same antigenic proteins. The immune responses induced by these antigenic proteins were evaluated by measuring the extent and duration of the skin reaction, known at the delayed-type hypersensitivity response (DTH). A DTH skin immune response was induced in 90% of the SonoPrep treated patients and the duration of the DTH skin reaction was similar in the treatment group versus the control group. “I think this is an innovative technology with interesting potential in vaccinology and modulation of immune responses to infectious pathogens” stated Dr. Libraty, an Assistant Professor of Medicine at the Center for Infectious Disease and Vaccine Research at the University of Massachusetts Medical School in Worcester.

Following the completion of this first study, Sontra had initially planned to complete a second human study at the University of Massachusetts Medical School using SonoPrep to facilitate the transdermal delivery of an influenza vaccine. Due to the current shortage of flu vaccines and concern by public health officials, Sontra has decided to donate its existing supply of flu vaccine to the medical school’s clinical partner, UMass Memorial Health Care and will instead commence a second vaccine study later this fall with a hepatitis A vaccine.

“We are very pleased with the promising results from our first transdermal vaccination study” stated Shikha Barman, PhD, Director of Transdermal Drug Development at Sontra. “We believe that our SonoPrep skin permeation technology can facilitate transdermal vaccination and improve clinical outcomes. Because SonoPrep controls the actual permeability of the skin surface, antigens can be precisely delivered and a powerful immune response can be induced by activating the Langerhan cells in the epidermis. To date the majority of vaccines are delivered by needle injection. Not only does SonoPrep have the potential to improve the efficacy of vaccines, transdermal vaccines also eliminate the risk of inadvertent needle generated disease transmission and patients always prefer pain-free therapy.”

About Sontra Medical Corporation (http://www.sontra.com)

Sontra Medical Corporation is a leading developer of transdermal drug delivery and diagnostic products that combine Sontra’s SonoPrep ultrasound- mediated skin permeation technology with synergistic biosensor and transdermal drug delivery technologies. Sontra is marketing the SonoPrep device and procedure tray for use with topical lidocaine to achieve rapid (within five

minutes) skin anesthesia. Products under development include: a continuous non-invasive glucose monitor developed in collaboration with Bayer Diagnostics and the use of SonoPrep for the transdermal delivery of vaccines, pain drugs and large protein biopharmaceuticals.

About UMASS Medical School (http://www.umassmed.edu)

The University of Massachusetts Medical School is one of the fastest growing academic health centers in the country and has built a reputation as a world-class research institution, consistently producing noteworthy advances in clinical and basic research. The Medical School attracts more than $154 million in research funding annually, 80 percent of which comes from federal funding sources. Research funding enables UMMS scientists to explore human disease from the molecular level to large-scale clinical trials. Basic and clinical research leads to new approaches for diagnosis, treatment and prevention of disease.

This press release contains forward-looking statements, which address a variety of subjects including, for example, the expected efficacy of the SonoPrep device in connection with vaccine delivery, the expected benefits, market opportunities and market acceptance of the SonoPrep device and technology, the expected size of the markets for the SonoPrep device and technology, and Sontra’s business, research and marketing strategies. Statements that are not historical facts, including statements about our beliefs and expectations, are forward-looking statements. Such statements are based on our current expectations and are subject to a number of factors and uncertainties, which could cause actual results to differ materially from those described in the forward-looking statements. The following important factors and uncertainties, among others, could cause actual results to differ materially from those described in these forward-looking statements: adverse results in product development, clinical trials, commercialization efforts and market acceptance; difficulties or delays in obtaining regulatory approvals to market products resulting from development efforts; difficulties or delays associated with sources of transdermal drugs; failure to obtain and maintain patent protection for discoveries; commercial limitations imposed by patents owned or controlled by third parties; dependence upon strategic partners and third-party distributors to develop, commercialize, market and sell products based on our work; the commercial success of products; and the requirement for substantial funding to conduct research and development and to expand commercialization and marketing activities. For detailed information about factors that could cause actual results to differ materially from those described in the forward-looking statements, please refer to Sontra’s filings with the Securities and Exchange Commission, including Sontra’s most recent Quarterly Report on Form 10-QSB. Forward-looking statements represent management’s current expectations and are inherently uncertain. We do not undertake any obligation to update forward-looking statements made by us.

Contacts:

Sean Moran, CFO

Sontra Medical Corporation

Tel: 508-553-8850

Evan Smith, CFA / Erica Pettit

KCSA Worldwide

Tel: 212-896-1251 / 212-896-1248

EX-99.2

EXHIBIT 99.2

Sontra Presents Promising Clinical Results in Patients with Diabetes from Glucose Monitoring Study

SonoPrep Ultrasonic Skin Permeation Device Enables Continuous Transdermal Glucose Monitoring

FRANKLIN, Mass., November 1, 2004 — Sontra Medical Corporation (Nasdaq SC: SONT) announced today that clinical results presented at the Diabetes Technology Meeting held in October in Philadelphia PA, demonstrate that its continuous non-invasive glucose monitoring system, being developed in collaboration with Bayer Diagnostics, reliably detected real-time changes in the blood glucose levels of patients with diabetes. The glucose flux biosensor measures the continuous flow of glucose through the skin, which is made permeable with the SonoPrep^® ultrasonic skin permeation device.

The study, conducted at Vanderbilt University, included twelve adult participants with either Type 1 or Type 2 diabetes. Each participant had three glucose flux biosensors placed on their skin, allowing glucose measurements to be collected every five seconds over an eight hour period. To challenge the glucose flux biosensor’s accuracy in detecting rapidly changing blood glucose levels, the blood glucose of each patient was increased or decreased through the intravenous administration of insulin or glucose in a controlled manner at rate of change at least two times greater than the usual rate experienced by patients with diabetes. Over 2,000 data points were evaluated per glucose biosensor. As a reference, blood glucose measurements were collected from an intravenous catheter. Completed data sets from the glucose flux biosensors showed a 90 percent correlation (r = .90) to reference blood glucose measurements. The glucose flux biosensor was able to reliably predict hypoglycemia (blood glucose<70 mg/dl) with 96% specificity and 77% sensitivity. The accuracy of the glucose flux biosensor was compared to Medtronic MinMed implanted CGMS sensors (n=23) and Cygnus Glucowatch-2 (n=13), which had correlations to reference blood glucose measurements of 82 % ( r = .82) and 70% (r. = .70), respectively.

“We are very pleased with the results of this study because it showed that our continuous non-invasive glucose monitor detects rapidly changing blood glucose over a very wide range,” stated Thomas W. Davison, PhD, Sontra’s President and Chief Executive Officer. “Over the past year, Sontra scientists have greatly improved the performance of the glucose flux biosensor. Not only did the glucose flux biosensor detect rapid changes, it was also able to detect hypoglycemic conditions, which has been a limitation of other continuous glucose monitors. We are excited about our glucose monitoring system because of its promise to address the major unmet market need for a truly continuous and non-invasive product in the rapidly growing $5 billion glucose monitoring market.”

For a copy of the poster that was presented at the Diabetes Technology meeting: www.sontra.com/pdfs/glumonihumanclinicalres_pres@diabtechmeetingoct2004.pdf

About Sontra Medical Corporation (http://www.sontra.com)

Sontra Medical Corporation is a leading developer of transdermal drug delivery and diagnostic products that combine Sontra’s SonoPrep ultrasound- mediated skin permeation technology with

synergistic biosensor and transdermal drug delivery technologies. Sontra is marketing the SonoPrep device and procedure tray for use with topical lidocaine to achieve rapid (within five minutes) skin anesthesia. Products under development include: a continuous non-invasive glucose monitor developed in collaboration with Bayer Diagnostics and the use of SonoPrep for the transdermal delivery of vaccines, pain drugs and large protein biopharmaceuticals.

SonoPrep is a registered trademark of Sontra Medical Corporation. All other company, product or service names mentioned herein are the trademarks or registered trademarks of their respective owners.

This press release contains forward-looking statements, which address a variety of subjects including, for example, the expected development, benefits and efficacy of the SonoPrep device and continuous glucose monitoring system, the expected benefits, market opportunities and market acceptance of the SonoPrep device and continuous glucose monitoring system, the expected size of the markets for the SonoPrep device and continuous glucose monitoring system, and Sontra’s business, research and marketing strategies. Statements that are not historical facts, including statements about our beliefs and expectations, are forward-looking statements. Such statements are based on our current expectations and are subject to a number of factors and uncertainties, which could cause actual results to differ materially from those described in the forward-looking statements. The following important factors and uncertainties, among others, could cause actual results to differ materially from those described in these forward-looking statements: adverse results in product development, clinical trials, commercialization efforts and market acceptance; difficulties or delays in obtaining regulatory approvals to market products resulting from development efforts; failure to obtain and maintain patent protection for discoveries; commercial limitations imposed by patents owned or controlled by third parties; dependence upon strategic partners and third- party distributors to develop, commercialize, market and sell products based on our work; the commercial success of products; and the requirement for substantial funding to conduct research and development and to expand commercialization and marketing activities. For detailed information about factors that could cause actual results to differ materially from those described in the forward-looking statements, please refer to Sontra’s filings with the Securities and Exchange Commission, including Sontra’s most recent Quarterly Report on Form 10-QSB. Forward-looking statements represent management’s current expectations and are inherently uncertain. We do not undertake any obligation to update forward-looking statements made by us.

Contacts:
Sean Moran, CFO	or	Evan Smith, CFA / Erica Pettit
Sontra Medical Corporation		KCSA Worldwide
Tel: 508-553-8850		Tel: 212-896-1251 / 212-896-1248

EX-99.3

Exhibit 99.3

Ultrasonic Pretreatment Enables Continuous Transdermal Glucose Monitoring

HAN CHUANG, SHIKHA P. BARMAN, HANNAH FARNHAM and MY-QUYEN TRIEU

Sontra Medical Corporation, 10 Forge Parkway, Franklin, MA 02038

Conclusions

1. Transdermal glucose monitoring can be achieved with ultrasonically permeated skin.

2. The sensor should exhibit better performance in regular uses compared to glucose clamping studies.

3. Sensor performance may be further enhanced by minor drift compensation and wireless operation.

Single point calibration is both convenient and practical, and continuous glucose monitoring can be easy, safe and reliable.

Results

1. Noisy data to be further investigated.

2. Required only 89±6 min for sensor break-in.

3. Sensor tracked BG reading on all 29 data sets, with an average r = 0.90 and 96% in A+B region of Clarke error grid.

4. Reliably predict hypoglycemia with 77% sensitivity, and low false positive rate with 96% specificity.

5. No pain or irritation during SonoPrep and sensor operation.

Introduction

In an initial clinical trial, we have demonstrated that continuous glucose sensing can be achieved transdermally, post ultrasound skin pretreatment using SonoPrep®. In this study, we present improved glucose monitoring using a novel hydrogel-based glucose flux sensor that provides a continuous measurement of glucose amperometrically.

Methods

The sensor was comprised of a planar, three-electrode transducer with enzymatic chemistry embedded in a specialized hydrogel layer. The hydrogel offered multiple functionalities as an enzyme reservoir and a skin-sensor coupler, and maintained osmotic gradient for glucose extraction from the skin. Three target skin sites on each subject were first treated with SonoPrep. Glucose sensors (3/subject, 36 total) were then applied to the skin sites whereupon current and time data were collected. As reference, frequent arterialized venous plasma glucose (BG) readings were collected and analyzed with a standard glucose analyzer. Data sets were analyzed using a MATLAB-based data processing software.

Results

Totally 36 sensor data sets were collected from 12 patients with diabetes. Two sensors had mechanical/electronic failure. Five data sets had excessive noise to be further investigated. Totally 2039 sensor-BG data pairs from 29 data sets were analyzed with both an individually optimized and an independent algorithm. When analyzed with the independent algorithm where single reference BG values were used for sensor calibrations, good sensor-BG correlations (average r = 0.90) were maintained over a period of 7.5 hours. 96% of sensor-BG data pairs falls in A+B regions in the Clarke error grid. 77% (164 out of 212) hypoglycemic events (BG<70 mg/dL) was successfully predicted. SonoPrep treatments averaged 15 seconds, and the glucose sensor only required an average of 89±6 minutes for break-in.

Conclusions

Due to their placement on skin, the sensors were easy to apply and comfortable, with no possibility of infection or bleeding. Furthermore, ex vivo sensors may have longer lifetime due to lower propensity for protein deposition and foreign body response, compared to implant-based devices. Based on retrospective computing, we demonstrate that blood glucose values may be reliably predicted in real time using the sensor output and a convenient calibration protocol.

Study Highlights

1. Glucose clamping studies: Plasma glucose range 35-372 mg/dl, decrease rate 0 ~ -6.9 (mg/dl)/min, increase rate 0 ~ 6.5 (mg/dl)/min.

2. Tight glycemic control by alternating glucose and insulin challenges through i.v. infusions.

3. Individually optimized algorithm uses each data set’s optimal lag time and baseline for data analysis.

4. Independent algorithm developed from a separate glucose clamping study.

Complete SonoPrep and glucose sensor system

Potentiostat recorder

SonoPrep base unit

Ultrasonic generator

Sensor assembly

Patient Data

12 Patients in total, 8 males/ 4 Females

9 Type 1 PWD’s /3 Type 2 PWD’s

Average age = 35 years, range 19 to 46 years-old

Average years w/ Diabetes = 15, range 3 to 40 years

Number of insulin pump users = 4

Some patients with complications, such as poor circulation, retinopathy, dehydration and hypoglycemic tendencies

A noisy data set

A typical data set

Conclusions

1. Transdermal glucose monitoring can be achieved with ultrasonically permeated skin.

2. The sensor should exhibit better performance in regular uses compared to glucose clamping studies.

3. Sensor performance may be further enhanced by minor drift compensation and wireless operation.

4. Single point calibration is both convenient and practical, and continuous glucose monitoring can be easy, safe and reliable.

Acknowledgement

We appreciate Bayer Diagnostics for collaboration and contribution to this extensive study.

Results

1. Noisy data to be further investigated.

2. Required only 89?6 min for sensor break-in.

3. Sensor tracked BG reading on all 29 data sets, with an average r = 0.90 and 96% in A+B region of Clarke error grid.

4. Reliably predict hypoglycemia with 77% sensitivity, and low false positive rate with 96% specificity.

5. No pain or irritation during SonoPrep and sensor operation.

EGA, individually optimized

EGA, independent analysis