# ACTIONS OF HPD AND PHOTORADIATION OF MAMMARY TUMORS

> **NIH NIH R01** · UNIVERSITY OF ROCHESTER · 1992 · $233,011

## Abstract

Photodynamic therapy (PDT) is a promising new cancer intervention that is
based on the photoactivation of a systemically administered
photosensitizing dye.  Absorption of visible light by the dye results in
the photosensitized formation of singlet oxygen (1O2) and subsequent
cytotoxic reactions of 1O2 with cellular substrate.  Considerable effort
has been devoted to elucidate the mechanisms by which these photosensitized
oxidations contribute to tumor destruction.  These studies proposed here
are designed to continue and extend our efforts, begun 10 years ago, to
elucidate the biochemical basis for PDT-induced cytotoxicity and to use the
new knowledge acquired in this effort to enhance the efficacy of the
therapy.  The proposed studies are interdisciplinary in nature, applying
the expertise of scientists in biochemistry, biophysics, radiology and
physics.  Important new questions have arisen during the course of the
previous grant period.  Modifications in the photoradiation regimen have
been shown to be capable of producing significant differences in inhibition
of tumor growth.  The mechanisms underlying these effects remain to be
determined and experiments designed to accomplish this form an important
focus for the proposed renewal.  Different xenografts grown in the same
host (nude mouse) possess significantly different sensitivities to PDT/
This finding has raised important questions concerning mechanism of action,
sensitizer uptake and distribution, intrinsic differences between tumor
cell types, etc.  These studies will be pursued as will closely related
problems in primary and transplanted rat mammary tumor models.  Five
specific aims have been formulated:  (1) to optimize the drug and
irradiation regimen in PDT of the R3230AC tumor in vivo and to quantitate
an optimum therapeutic ratio in that system; (2) to determine sensitivities
of primary and transplantable NMU tumors in the same host and to determine
mechanisms differences in sensitivity between the R3230AC and the human
mesothelioma xenograft in the nude mouse; (4) to perform several direct
experimental tests in vitro  and in vivo of the mechanisms whereby
fractionated and reduced dose rate irradiation enhance the therapeutic
response; and (5) to investigate the problem of recurrent tumors in PDT.
In all of these studies, biochemical methods will be used in close
conjunction with NMR imaging and spectroscopy, fluorescent probes, FACS,
and radioactive labeling techniques.

## Key facts

- **NIH application ID:** 3174424
- **Project number:** 2R01CA036856-09
- **Recipient organization:** UNIVERSITY OF ROCHESTER
- **SAM.gov UEI:** F27KDXZMF9Y8
- **Principal Investigator:** RUSSELL HILF
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1992
- **Award amount:** $233,011
- **Award type:** 2
- **Project period:** 1992-07-10 → 1997-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3174424

## Citation

> US National Institutes of Health, RePORTER application 3174424, ACTIONS OF HPD AND PHOTORADIATION OF MAMMARY TUMORS (2R01CA036856-09). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3174424. Licensed CC0.

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