Detection of Early Lung Cancer Using Low Dose Photofrin II

Detection of Early Lung Cancer Using Low Dose Photofrin II* Stephen lAm, M.D., F.C.C.P.; Branko lblcic, Ph.D.;

David McLean, M.D.; ]aclyn Hung, M.Sc.; Mladden Korbelik, Ph.D.; and A. Edward Profio, Ph.D. t

Fluorescence imaging using hematoporphyrin derivative (HpD) or PhotoErin D as a tumor marker has heen used Cor loaalintion ofearly bronchogenic carcinoma. Wider clinical appUcation of HpD or Photofrin D as a cancer imaging agent has heen hampered by the potentially serious and prolonged skin photosensitivity. Using a sensitive Ouores-

cence bronchoscope system with a ratio ftuorometer probe, carcinoma in situ was detected in four patients with low dose Photofrin D (0.!5 mg/kg) with no apparent skin phototoxicity to 30 J/cm• visible Ught on skin photosensitivity (Clam 1990; 97:333-37) test.

ung cancer is the most common cause of cancer death in North America. The overall five-year survival of patients with lung cancer ranges from 10 to 13 percent. 1•2 In patients with early lung cancer (TIS NO MO and T1 NO M0), 3 the five-year survival is over 90 percent after surgical resection:U Fluorescence bronchoscopy following administration of hematoporphyrin derivative (HpD/Photofrin I) or its partially purified preparation (dihematoporphyrin ether/ ester Photofrin II, QLT Phototherapeutics, Vancouver, Canada) has been used to facilitate the detection and localization of roentgenographically occult early lung cancers.&-14 However, wider clinical application ofHpD or Photofrin II as a ftuorescent marker for early lung cancer is hampered by the potentially serious and prolonged skin photosensitivity that can last for four weeks or more. 15•16 In this study, we demonstrated that carcinoma in situ can be detected using a dose of Photofrin II that is much lower than that conventionally used with no apparent skin photosensitivity.

showed a squamous cell carcinoma. A bilobectomy was performed. Microscopic examination of the bronchial resection margin showed residual carcinoma in situ. The patient was referred for photodynanlic therapy three months posttboracotomy. Patient 3, a 58-yearold man had a right upper lobectomy for a squamous cell carcinoma nine months earlier. The bronchial resection margin showed residual carcinoma in situ. He received postoperative radiotherapy with a radiation dose of 4,000 cGy in 20 fractions over four weeks. One month prior to 8uorescence bronchoscopy, he was investigated in another hospital for cough. He was found to have radiation fibrosis in the right apex. Bronchoscopy showed a slightly granular mucosa in the bronchial stump, but a normal right main stem bronchus. Bronchial biopsy in both areas showed carcinoma in situ. Patient 4, a 61-ye&M)ld man with severe chronic obstructive lung disease, had a sleeve left upper lobectomy for a squamous cell carcinoma seven weeks earlier. The bronchial resection margin showed residual carcinoma in situ.

Bronchoscopy Fiberoptic bronchoscopy was carried out under local anesthesia 24 hours after intravenous injection of 0.25 m!Vkg Photofrin II. Following white light examination, 8uorescence bronchoscopy was carried out.

Fl110R18cence Bronchoscopy MATERIALS AND METHODS

.lbtfmt&. Four patients with roentgenographically occult carcinoma in situ were studied. Patient 1, a 59-ye&N)Id smoker with severe chronic obstructive lung disease, presented with hemoptysis. Chest x-ray film and cr scan did not show any endobronchial abnormality. Sputum cytology showed squamous carcinoma cells. Bronchoscopy at another hospital failed to localize the source of the cancer cells. Patient 2, a 67-ye&N)ld smoker with moderately severe chronic obstructive lung disease, presented with hemoptysis. Chest x-ray film was negative for malignancy. Bronchoscopy revealed a small polypoid tumor in bronchus B- of the right lower lobe. Biopsy *From the Cancer Control Agency of British Columbia, Vancouver, B.C., Canada and ttbe University of California, Santa Barbara. This study was supported by the National Cancer Institute of Canada and the BC Health Care Research Foundation. Manuscript received May 11; revision accepted July 17. &print requut&: Dr: lam, 2775 Heather Stn!et, \fancouver; BC,

Clinadtl V5Z 3]5

Fluorescence bronchoscopy was carried out using a 8uorescence bronchoscope system and a ratio 8uorometer probe as described previously by one of us (AEP)...,. The excitation light (wavelength 405 nm) was from a krypton ion laser. The violet light was conducted to the tip of a fiberoptic bronchoscope, via a 850 jl.m quartz fiber inserted into one of the biopsy channels. The fiber had a microlens at the tip. Fifteen milliwatts of power was used for examination. Direct viewing of 8uorescence from the bronchial surface was made using a 690 nm, 10 nm bandpass interference filter and a third generation image intensifier. Fluorescence intensity was semiquantitated by ratio 8uorometry. 11 •13•14 Red 8uorescence from tissues containing Photofrin II was ratioed against the green auto8uorescence of normal bronchial tissues. The 8uorescent light was picked up by another quartz fiber inserted into the second channel of the bronchoscope. The red/green ratio was displayed on a digital readout and also as an audio signal with the pitch of the signal proportional to the magnitude of the red/green ratio. The ratio was independent of the distance and angle of the violet excitation light source. 11 •1• In patients 2 to 4, the red/green ratio detected over a normal C'control') CHEST I 97 I 2 I FEBRUARY,1990

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area of the bronchial tree was normalized to a value of 1.0. Measurements were then made over the bronchial resection margin and other parts of the bronchial tree. For patient 1, the normal looking main carina was used as control. This area was later confirmed to be normal by biopsy. A red/green ratio of above 2.0 was considered to indicate the possible presence of tumor." Biopsy specimens were taken from all areas with increased fluorescence and were examined pathologically.

Table 1-Bronclwacopic Finding~* RIG Ratios Patient

1

LUDB LB•-LB• SC LUL

Skin photosensitivity was tested before and within 72 hours after Photofrin II administration. Testing was done on the lower back. Test squares 1.5 em x 2.5 em were exposed to visible light (400750 nm) to cover the entire visible absorption spectrum ofPhotofrin II. The light source for the testing was from a SOOW projector lamp with a filter to remove infrared light. The power output was measured by a radiometer. The test light dosage was 15 to 30 J!em• in 5 Jlcm• increments. Skin reaction was read at 24 hours after light exposure. Skin reaction was graded 1 + , 2 + , or 3 + . A 1 + reaction was equivalent to the minimum erythema dose and was the light dose which induced a mild reddening of the skin without edema, blistering, or necrosis. A 2 + reaction referred to moderate redness with edema but no blistering or necrosis. A 3 + reaction referred to redness, edema, and blistering. Normal skin without Photofrin II does not show any reaction to visible spectrum light. Following localization of the tumor, the patients received an additional 1. 75 mgllcg Photofrin II (total dose 2 mglkg) for photodynamic therapy. A third skin photosensitivity test was performed 72 hours after the second injection. The test light dosage was 5 to 20 J!cm• in 5 J!cm• increments. Seven other patients with obstructive endobronchial tumors who received 2 mgllcg Photofrin II for photodynamic therapy were also tested for skin photosensitivity at one to three weekly intervals to determine the duration of the skin photosensitivity. The study was approved by the Clinical Investigations Committees of the Cancer Control Agency of British Columbia and the University of British Columbia.

REsuLTS The findings on white light bronchoscopic examination and ftuorescence imaging are shown in Th.ble 1. Subtle mucosal changes were observed at five of the ten tumor sites. Positive ftuorescence was observed in all ten sites. Elevated red-green ratios in the tumor area vs the control area were also observed at all ten sites. In areas of the bronchial tree that were not involved by tumor, the red-green ratios varied between 0.9 to 1.8. The ratios were less than 1.6 in all except one area. The one nontumor area with a redgreen ratio of 1.8 in patient 3 showed moderate atypia on biopsy. Following localization of the tumor area(s), the patients received an additional 1. 75 mglkg Photofrin II. Repeat ftuorescence bronchoscopy just prior to photodynamic therapy 48 hours after administration of Photofrin II in three of the four patients showed that the red-green ratios in the tumor areas increased from a mean of 4.8 (range 3.0 to 9.5) to a mean of7.9 (range 5. 7 to 10.0). Skin photosensitivity testing before and after injection of0.25 mg/kg Photofrin II did not show any skin reaction to 30 Jlcm2 visible light. Following injection

WLB +t

RB•-RB•sc

Skin PhotosemUivity Test

334

Location of CIS Lesions

+t

RUL

RB• 2

3 4

Bronchial stump Bronchial stump RMS Bronchial stump

+t +t +t

FB

Tumor

Nontumor

+ + + + + + + + + +

9.0 9.5 9.0 9.5 9.5 8.0 4.2 3.2 3.0 4.4

1.1 ±0.1

1.0±0.1 1.4±0.3 1.3±0.1

*LUDB, left upper divisional bronchus; SC, suhcarina; LUL, left upper lobe entrance; RUL, right upper lobe entrance; RMS, right main stem bronchus; CIS, carcinoma in situ; WLB, white light bronchoscopy; FB, fluorescence bronchoscopy; RIG, red-green ratio, tumor versus control site. tGranular mucosa. tThickened mucosa.

of a total of 2 mglkg Photofrin II, patient 1 showed a 1 + reaction to 5 Jlcm2 visible light, patient 2 showed 1 + reaction to 10 J/cm2 visible light, and patient 4 showed + 1 reaction to 5 Jlcm2 visible light. Repeat skin photosensitivity testing was not done in patient

3. The duration of skin photosensitivity in seven other patients who had received 2 mg/kg Photofrin II is shown in Figure 1. All seven patients displayed no skin reaction when exposed to outside light at eight weeks postinjection. On skin photosensitivity test, they were able to tolerate ~ 15 Jlcm2 visible light without skin reaction. DISCUSSION

Almost all of the roentgenographically occult, sputum cytology positive lung cancers are squamous cell carcinomas. 4 Detection and localization of these occult lung cancers have long presented a diagnostic challenge. Even for experienced endoscopists, carcinoma

2

4 68 Weeks Post Photofrin II

10

FIGURE 1. Duration of skin photosensitivity in seven patients who

had received 2 mg/kg Photofrin II intravenously.

Dellcllon of Early Lung Cancer (Lam et el}

in situ is bronchoscopically visible in less than 30 percent of cases and microinvasive tumors are visible in only about two thirds of cases. 17 The earliest recognizable changes are subtle consisting of increase in granularity or a slight thickening of the bronchial mucosa. 18 These changes were observed in half of the tumor sites in this study. When no abnormality is visible, localization of these tumors is time consuming and can be difficult. Multiple examinations may be necessary. 4 For this reason, the use of fluorescent "tumor markers" has been developed to facilitate detection and localization of these early lung cancers. Hematoporphyrin derivative or Photofrin II have been the most extensively studied for the detection and localization of small as well as large bronchial cancers.6-14·19 Fluorescence diagnosis of tumors is based on the principles that HpD and Photofrin II emit red fluorescence (with peaks at 630 nm and 690 nm when excited by a violet light near 405 nm) that can be detected by special imaging devices; and HpD and Photofrin II are preferentially retained by tumor tissues compared to most nonmalignant tissues from hours to days after intravenous injection. The tumor can consequently be imaged or detected because it can be differentiated from the surrounding normal tissue by its more intense fluorescence. Ifa different fluorescent tumor marker is used, the principles remain the same although a different excitation wavelength, filtering, and detection system may be required. Several fluorescence detection endoscopic systems have been developed in the United States, Japan, and Europe.6- 14·20 •21 The results of clinical testing in both large and small bronchial cancers using image fluorescence bronchoscopy (IFB) and rationing fluorometer probe (RFP) have been described by Doiron, Profio, Balchum and coworkers previously. s- 14 Both large and small bronchial cancers of all histologic types showed positive fluorescence. In seven patients with carcinoma in situ lesions who had received 2 mg/kg Photofrin II, the sensitivity of IFB and RFP was 93 percent and 70 percent, respectively. The specificity of IFB and RFP was 50 percent and 100 percent, respectively. When both methods were used together in the same patients, the sensitivity and specificity was 98 percent and 100 percent, respectively. 14 Clinical experience at the Mayo Clinic using 2 mg/kg HpD and a nonimaging fluorescence detection system showed positive fluorescence in all five patients with roentgenographically occult but bronchoscopically visible cancers. Fluorescence examination was instrumental in localizing ten of 11 centrally located squamous cancers that were bronchoscopically invisible. There were three peripheral lung cancers that were not localized on fluorescence examination because they were beyond the reach of the relatively large two

channel flexible fiberoptic bronchoscope. 7 Experience in Japan using 3 mg/kg HpD or 2.5 mg/kg Photofrin II and an endoscopic fluorescence spectroscope showed that distinct fluorescence with the characteristic HpD/Photofrin II pattern could be recognized in all five cases of early lung cancer. 7 Despite these encouraging results, wider clinical application ofHpD/ Photofrin II as a fluorescent tumor marker for the detection of early lung cancer is hampered by the potentially serious and prolonged skin photosensitivity. 15·22 The recent identification of the active component in Hpl)23·24 allows partial purification of this drug and reduction in the drug dose and severity of the skin photosensitivity. This partially purified preparation- Photofrin II still carries significant skin photosensitivity potential at the currently recommended dose of 2 mg/kg. Patients receiving Photofrin II have to remain out of bright light for a minimum of 30 days in order to avoid skin burns. 22 This is a major drawback in wider application of HpD/Photofrin II in the detection of early lung cancer and for staging the extent of proximal endobronchial spread oflung cancer prior tosurgery. Preliminary studies in animals suggest that lower, nontherapeutic doses of Photofrin II may be effective in localization of micrometastases in regional lymph nodes25 and early carcinoma of the urinary bladder. 20 Furthermore, low (<0.5 mg/kg) doses ofPhotofrin II may eliminate skin photosensitivity.25 In this study, by using a sensitive endoscopic fluorescence detection system, we have shown, for the first time that carcinoma in situ can be detected with a much lower dose of Photofrin II than that used for photodynamic therapy. An earlier study by Balchum et al 12 using a similar ratio fluorometer probe showed a mean tumor to control red/green ratio of 6.1 (range 2.8 to 10.3) following injection of 2 mg/kg Photofrin II. In our present study, three of our patients with carcinoma in situ who were given 2 mg/kg Photofrin II showed a mean tumor to control red/green ratio of 7.9 (rough 5.7 to 10.0). Using an endoscopic fluorescence spectroscope system, Kato and Cortese7showed that the fluorescence intensity in the tumor was eight to 14 times higher than normal tissue following injection of 3 mg/kg HpD or 2.5 mg/kg Photofrin IJ.7 Despite using a dose of Photofrin II that is one-eighth to one-tenth of that in these studies, the tumor to control fluorescence intensity observed in this study was about 50 percent of that found following injection of2.0 mg/kg Photofrin II. This suggests that too high a dose of Photofrin II may increase the drug concentration in normal tissues more than that in tumor tissues resulting in a loss of contrast between tumor and normal tissues. Another significant finding in this study is that in low doses (::s0.25 mg/kg), Photofrin II may be without CHEST I 97 I 2 I FEBRUARY, 1990

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skin phototoxicity. Sunburn in normal skin without HpD/Photofrin II is due to exposure to ultraviolet light. The effects of ultraviolet light are relatively easy to block with standard sunscreens. However, the major cause of clinically significant photosensitivity reaction in patients who had received HpD or Photofrin II is due to exposure to visible light in the solar spectrum; the reaction cannot be blocked with nonopaque sunscreens. Using visible light alone (400 to 750 nm) to cover the entire visible absorption spectrum of Photofrin II, our patients in this study who had received 2 mWkg Photofrin II were able to expose to normal amounts of outside light without a clinically apparent skin photosensitivity reaction four to eight weeks after receiving the drug. Serial skin testing in seven of these patients showed that at eight weeks postinjection, they were able to tolerate 2: 15 Jlcm2 of test light. Using a slightly different test light that contains some ultraviolet light (300 to 800 nm), Razum and co-workers 16 in Southern California observed that the duration of clinically significant skin photosensitivity was about six to seven weeks in patients who had received 2 mWkg Photofrin II. Three of their nine patients who had serial skin tests were able to tolerate 19.5 Jlcm 2 simulated solar spectrum light at this time. The precise test dose that corresponds to a safe exposure to an unlimited amount of visible light in the natural environment irrespective of climatic conditions has not been established in patients who have received HpD or Photofrin II. We increased the highest test dose to 30 Jlcm2 for our patients who were given 0.25 mWkg Photofrin II to allow for variation in individual skin responses and variation in light intensity in the natural environment to decrease the probability of a false negative skin test. Despite the higher light dose, no skin reaction was observed in all four patients who were tested. Since we did not perform a drug dose escalation study, we were unable to determine whether there was a threshold for skin photosensitivity reaction between 0.25 mWkg to 2 mWkg Photofrin II. Although a larger study population is needed to assess the sensitivity and specificity of low dose Photofrin II as an imaging agent for the detection of early lung cancer, and to determine the incidence of skin photosensitivity, the results in this study are encouraging. There may indeed be more hope for lung cancer patients if standard bronchoscopy can be used to detect lung cancer while the disease is still curable. If the recent finding that even nonsquamous cell carcinomas can be detected by sputum cytology using monoclonal antibodies directed to cell surface antigens for an average of two years in advance of the clinical appearance of lung cancers is confirmed, the next diagnostic challenge for the bronchoscopist is to apply techniques such as the one described in the present study to detect and localize these cancers in 338

the roentgenographically occult asymptomatic stage without toxicity such as skin photosensitivity. ACKNOWLEDGMENT: We would like to thank Jean LeRiche MB, li1r interpretation of the biopsy and cytology specimens, and John J.P. Fengler, M .A.Sc. for engineering assistance. REFERENCES

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Annual Meeting, NAMDRC The Annual Meeting of the National Association of Medical Directors for Respiratory Care will be held March 9-10 at the Hotel Nikko, San Francisco. For information, contact the NAMDRC Executive Office, 1050 17th Street, NW, Suite 840, Washington, DC 20036 (202:785-1196).

Targets of TB The 9th Annual Tuberculosis Symposium will be held March 8 and 9 at the Hyatt-Regency Hotel, Los Angeles (711 South Hope Street), sponsored by the American Lung Association of Los Angeles County. For information, contact Pam Hoytt, RN, ALA of LAC, 5858 Wilshire Blvd, Los Angeles 90036-0926 (213:935-5864).

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