7. The Photohem Hematoporphyrin-Series Photosensitizer
Photohem is a preparation for photodynamic therapy (PDT) of cancer officially licensed in Russia. It is an analogue of widely used abroad preparations Photofrin II, Photosan, Hematoporphyrin Derivatives (HpD) which is not less active in therapeutic terms.
It can be selectively accumulated and stay in malignant tumors, activate under the light exposure with a wavelength of 630 nm, and then either fluoresce in the red spectral range, or cause phototoxic reactions in a tumor tissue. These features allow to use it for both diagnosing the tumors, and their destruction.
Photohem can be used in clinical oncology for performing PDT in accordance with a radical program in the following cases:
- obligate pre-cancer states (stage III dysplasia);
- pre-invasion and early invasive cancer (T1N0M0);
- residual tumors after radiotherapy;
- early recurrent cancer (and the second metachronous cancer) after surgery.
The Photohem indications for performing PDT in accordance with a palliative program are the following:
- stenosis types of bronchogenic, esophageal and colon cancer;
- inoperable stage III - IV malignant tumors resistant to chemo- and radiotherapy;
- intracutaneous metastasis of Kaposi's sarcoma and breast cancer.
Photohem is used in case of the following tumor localizations: skin, upper respiratory tract, trachea, bronchi, mouth cavity, esophagus, stomach, rectum and colon, bladder, vagina, uterine cervix, endometrium, and also in case of other kinds of tumors available for direct and endoscopic laser irradiation.
In case with a residual tumor after a PDT course it is possible to perform PDT sessions again with the intravenous administration of the preparation with an interval of 1 month. Due to the low dark toxicity of Photohem it is possible to combine PDT with surgery, chemo- and radiotherapy.
In 1996 clinical trials of Photohem were successfully completed. By now, more than 1500 patients have undergone PDT courses with this preparation. Significant therapeutic effect was found in 91 % patients. In 62 % of cases there was complete tumor resorption, and partial tumor resorption (more than double decrease of a tumor in size) was found in 29 % of cases. Complete recovery was diagnosed in 92 % of patients with early types of cancer.
According to the conclusion of leading experts, Photohem is a perspective highly-effective preparation for photodynamic therapy of cancer.
By order of the Ministry of Healthcare of the Russian Federation № 47 dated February 10, 1999, the Photohem preparation was licensed in the Russian Federation and registered for medical use and commercial production.
Clinical trials of PDT with photosensitizers of different groups
Photosensitizer
|
Trial start
|
Wavelength,
nm
|
Drug dose, mg/kg
|
Number of patients
|
Photohem
|
1992
|
630
|
1.5 – 3.5
|
156
|
Photosense
|
1994
|
675
|
0.5 – 1.5
|
170
|
Radachlorin
|
1998
|
662
|
0.3 – 1.5
|
72
|
Alasense
|
1999
|
630
|
locally
|
14
|
Efficiency of PDT with Photohem
Tumor localization
|
Number of patients
|
PDT results
|
CR
|
PR
|
NE
|
Skin cancer
|
79
|
61
|
18
|
0
|
Melanoma
|
3
|
1
|
2
|
0
|
Breast cancer
|
23
|
8
|
9**
|
6
|
Oropharyngeal cancer
|
21
|
11
|
10***
|
0
|
Larynx and lung cancer
|
11
|
5
|
6*
|
0
|
Cancer of gastrointestinal organs
|
9
|
3
|
6*
|
0
|
Other
|
10
|
3
|
4
|
3
|
TOTAL
|
156 (100 %)
|
92 (59 %)
|
55 (35 %)
|
9 (6 %)
|
CR – complete tumor resorption, PR – partial tumor resorption, NE – no effect
* - palliative PDT;
** - palliative PDT for 4 patients;
*** - palliative PDT for 5 patients.
| 