Aerosolized Liposomal 9-Nitro-20(S)-Camptothecin in Patients with Advanced Malignancies in the Lungs

Introduction:

Topoisomerase-I inhibitors have the capability to eradicate human tumors in xenograft models. Therefore human cancer cells are extremely sensitive to camptothecin [1]. Camptothecin analogues are nevertheless not curative in clinical settings probably because of poor distribution of the camptothecin lactone to the tumor cells in humans. We hypothesized that a modification of the formulation and a systemic delivery that avoids first pass in the liver may increase the therapeutic index. Aerosol delivery of liposomal 9-nitrocamptothecin (L-9NC) could also possibly have delay the opening of the lactone ring through liposomation. We have demonstrated that delivery through aerosolization of fine particles is associated with systemic absorption [2] but not with sustained levels of closed ring 9-nitrocamptothecin. Animal data obtained from nude mouse models show minimal toxicity and no weight loss, with substantial antitumor activity at reduced doses in comparison to oral administration against breast, lung, and colon cancer xenografts [3]. A Phase I study to determine the feasibility and safety of administering L-9NC by aerosolization for five consecutive days per week has been completed [4]. Two Phase II studies are on-going to test the efficacy of this drug administration in patients with lung cancer and in patients with endometrial cancers.

PHASE I STUDY

Patients and Methods:

Patients with primary or metastatic disease to the lungs were enrolled in this phase I study if they fulfill the following eligibility criteria:

• pathologic diagnosis of cancer,

• failure after standard cancer treatment,

• performance status (Zubrod PS) <3,

• pulmonary function >50% by spirometry and DLCO,

• normal organ function, and

• no symptomatic brain metastasis.

In the feasibility cohort, treatment was given every day for 5 consecutive days. The starting dose was 6.7µg/kg per day by aerosolization with an Aerotech II nebulizer and a flow rate of 10 liters per minute of air. The time of administration was then extended to 2, 4, or 6 weeks followed by 2 weeks of rest to determine feasibility. For the dose escalation part, the dose was increased stepwise from from 6.7 up to 26.6µg/kg/day Monday to Friday for 8 weeks followed by 2 weeks of rest.

For pharmacokinetics, plasma was obtained on day 4 or 5 of therapy to determine the pharmacokinetic profile of the drug. Bronchoalveolar lavages to measure the amount of 9-NC were performed on consenting patients. Disease was evaluated by CT scan of the chest every two courses. Pulmonary function was evaluated by pulmonary function tests.

Results:

Twenty four patients received treatment (Mean age 55 years (33–79), Median PS 1, 17 females and 7 males). There were 6 patients with lung cancers, 5 with endometrial cancers, 4 with cervical cancer, 3 with melanoma and sarcoma each, and 6 with various cancers. Mean FEV₁ and other pulmonary functions before treatment were at least 85 percent or more of predicted values.

Table 1: Pulmonary function during treatment

	FEV1			FVC			TLC			DLCO
	Baseline	Lowest	End	Baseline	Lowest	End	Baseline	Lowest	End	Baseline	Lowest	End
Mean	85	65	83	85	70	83	103	100	99	85	72	84
SD	22	18	29	19	19	26	16	27	22	15	19	17
CV (%)	26.0	27.3	34.8	22.4	26.8	30.6	15.8	27.2	22.3	18.0	26.3	19.8

Paired t test, two-tailed
P value	Baseline vs Lowest: vs End: 0.0001 0.107 Lowest vs. End: 0.006	0.256 0.004	0.590 0.014 0.194	0.0054 0.230 0.126

At 26.6µg/kg/day, the DLT was a chemical pharyngeal mucositis seen at the end of the first week in 2 patients and necessitating an early treatment discontinuation. Recovery was prompt after stopping treatment (within one week). This cohort was halted and a new cohort of four patients at a dose of 20.0µg/kg/day was started with 2 males completing treatment with few side effects, and 2 females requiring a dose reduction for grade 2 and 3 fatigue after 4 weeks of treatment. At doses of 13.3µg/kg/day, all patients tolerated the treatment well and this dose is the recommended dose for phase II studies.

Grade 1 or 2 side effects included cough in (67%), bronchial irritation (46%), sore throat (33%), nausea (62%), vomiting (33%), anorexia (33%), dysgeusia (33%), fatigue (50%), anemia and neutropenia (29%), and skin rash around the face mask (21%). No grade >3 neutropenia was observed. No cumulative toxic effects were observed in 7 patients, who received more than one course.

There was a decrease in pulmonary function tests during treatment (Table 1). Mean percent predicted FEV₁ function dropped by 20% during aerosol therapy (p<0.0001) and improved to 83% of predicted value upon cessation of therapy. The mean end-of-treatment value was not significantly different than the baseline (p=0.107). TLC values were virtually unchanged and DLCO values were closely comparable to FVC results. Three patients with extensive pulmonary tumor involvement had reversible drop in FVC and/or FEV₁ to less than 50%, but recovered after cessation of therapy.

A partial remission was observed in 2 patients with endometrial carcinoma metastatic to the lungs only. A partial remission of a liver metastasis was also observed in a patient with endometrial cancer treated at 13.3µg/kg/day, demonstrating the systemic potential of aerosol delivery of this drug.

At the 13.3µg/kg/day dose, total 9NC plasma concentrations increased for 2 to 3 hr from the start of treatment reaching a mean (±SD) peak concentration of 37.7±20.2 ng/ml at 2 hr (range: 13.6–58.0 ng/ml) (Fig 1). Mean (±SD) clearance of 9NC was biphasic with a T_1/2α of 1.9±1.4 hr and a T_1/2ß of 16.4±10.5 hr. Pharmacokinetics were proportional to the dose in the range tested (6.7–20.0µg/kg/day). The area-under-the-curve (AUC) of the lactone form measured in the last two patients comprised only 3.2 and 3.5% of the total 9NC. 9NC concentrations in BAL fluids were >4.2 to >10.6 times higher that those measured concurrently in the plasma.

Figure 1: Pharmacokinetics of liposomal 9-nitrocamptothecin (9-NC). Mean (±SD) plasma levels in five cancer patients following treatment with 9-nitrocamptothecin liposome aerosol at 6.7µg/kg/day and administered by mouth-only breathing.

Phase II non-small cell lung cancer study:

In the phase I study, stable disease was observed in 3/6 patients with non-small cell lung cancers, hence a phase II study was initiated. Patients with operable or advanced lung cancer were eligible if they fulfilled the following eligibility criteria:

• pathologic diagnosis of non-small cell lung cancer,

• failure after standard cancer treatment or eligible for a neoadjuvant approach,

• performance status (Zubrod PS) <3,

• pulmonary function >50% by spirometry and DLCO,

• normal organ function, and

• no symptomatic brain metastasis.

The initial dose is 13.3µg/kg/day Monday to Friday for 8 weeks followed by 2 weeks of rest. Patients with operable disease are reevaluated after 4 weeks of therapy to ensure disease is not progressive, and patients with advanced disease are evaluated with an imaging study after each course of treatment (8 weeks). Patients with operable disease receive only 8 weeks of treatment prior to surgery. A two-step modified Simon design is used.

To date, six patients have been treated. Two patients had stable disease and receive more than 8 weeks of treatment. Four patients progressed. Of these, two patients underwent surgery after 4 weeks of treatment. No grade >3 side effects have been observed. The study still needs to accrue 3 patients to complete the first step of the Simon design.

Phase II endometrial cancer study:

Because responses were noted in 2/5 patients with endometrial cancers, a phase II study has been initiated. Patients with metastatic endometrial cancer are eligible if they fulfill the following eligibility criteria:

• pathologic diagnosis of endometrial cancer,

• failure after standard cancer treatment,

• performance status (Zubrod PS) <3,

• pulmonary function >50% by spirometry and DLCO,

• normal organ function, and

• no symptomatic brain metastasis.

The initial dose is 13.3µg/kg/day Monday to Friday for 8 weeks followed by 2 weeks of rest. Patients are evaluated with an imaging study after each course of treatment. A two-step modified Simon design is used.

To date, three patients have been treated. One had a minor response, one had a mixed response with a shrinkage of the smaller lung metastases and no response in the bigger lesions, and one is too early for evaluation. No grade >3 side effects have been observed. The Gynecology Oncology Group has accepted to perform a similar study to confirm the potential of aerosol drug administration.

Discussion:

Previous clinical studies of 9NC have used oral administration. In these studies, the main toxicity profile of 9NC was hematologic with anemia and neutropenia, and gastrointestinal with nausea, vomiting, and anorexia [5]. Another difficult side effect of oral administration was chemical cystitis with hematuria [5]. In the present study, the most remarkable finding was the lack of hematologic toxicity, the mechanism for which we do not yet have an explanation. There was a reversible non-clinically significant loss of pulmonary function, more pronounced in patients with widespread lung involvement with metastases. Nausea and vomiting were observed in a few patients and was very manageable. For reasons that are not completely clear, the toxicity profile after inhalation is milder than the one observed after oral administration. While aerosol doses were lower than those administered orally, 9NC plasma levels were similar to those observed after oral ingestion.

The aerosol droplet size of the 9NC liposomal complex is in the range that optimizes alveolar deposition (1 to 3 microns). Alveolar-capillary exchange of drug is through the pulmonary vein, making inhalation therapy a method of sustained arterial delivery. This would allow first pass presentation of drug to cancer sites. Further enrollment in the phase II studies will help answer the viability of administering liposomal 9NC by aerosolization.

Acknowledgments:

This work was supported in part by The Clayton Foundation.

References:

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2. Gilbert BE, C Knight, FG Alvarez, et al. 1997. Tolerance of volunteers to cyclosporine A-dilauroylphosphatidylcholine liposome aerosol. Am. J. Respir. Crit Care Med. 156: 1789–1793.

3. Knight V, ES Kleinerman, JC Waldrep, et al. 2000. 9-Nitrocamptothecin liposome aerosol treatment of human cancer subcutaneous xenograft and pulmonary cancer metastases in mice. Ann. N.Y. Acad. Sci.

4. Verschraegen CF, Gilbert BE, Loyer E, et. al. 2004. Clinical evaluation of the delivery and safety of aerosolized liposomal 9-nitro-20(s)-camptothecin in patients with advanced pulmonary malignancies. Clin Cancer Res. Apr 1;10(7):2319–26.

5. Verschraegen CF, Gupta E, Loyer E, et al. 1999. A phase II clinical and pharmacological study of oral 9-nitrocamptothecin in patients with refractory epithelial ovarian, tubal or peritoneal cancer. Anti-Cancer Drugs 10:375–383.