Journal of Immunotherapy
`13:201—207 © 1993 Raven Press, Ltd., New York
`
`Phase I/II Study of Murine Monoclonal Antibody-Ricin A
`Chain (XOMAZYME-Mel) Immunoconjugate plus
`Cyclosporine A in Patients with Metastatic Melanoma
`
`K. Selvaggi, iE. A. Saria, TR. Schwartz, §D. R. Vlock, is. Ackerman, iN. Wedel,
`*J. M. Kirkwood, 1H. Jones, and ”M. S. Ernstoff
`
`Divisions of Hematology and *Oncology, Department of Medicine, and TDepartment of Pharmacy and Therapeutics,
`Pittsburgh Cancer Institute, University of Pittsburgh, Pittsburgh, Pennsylvania, iXOMA Corporation, Berkeley,
`California, §Division of Oncology, Department of Medicine, Brigham and Women’s Hospital, Boston,
`Massachusetts, and "Division of Oncology, Dartmouth—Hitchcock Medical Center, Lebanon, New Hampshire, USA.
`
`
`
`Summary: XOMAZYME-Mel (XMMME-OOl-RTA) is an immunoconjugate
`comprised of ricin A chain conjugated to a murine monoclonal antibody di-
`rected against high molecular weight melanoma antigens. Although not neces-
`sarily related to increased toxicity or decreased efficacy, the development of
`anti-immunoconjugate antibodies may limit repetitive dosing with an immuno-
`conjugate. We evaluated the role of cyclosporine A in blocking the antibody
`response in patients with melanoma treated with XMMME-OOl—RTA. Patients
`received cyclosporine in divided daily doses to achieve serum levels by HPLC
`of 150—200 ng/ml on days 1—22. On day 3, XMMME-OOl-RTA was begun at
`dosages 0.2—0.6 mg/kg daily for 5 days. Treatment was repeated every 35 days.
`Three patients were treated in each dosage tier (0.2, 0.4, 0.6 mg/kg). Nine
`patients were entered and all nine were evaluable. Patients had histologically
`confirmed melanoma. Metastatic sites included skin, soft tissue, and lymph
`nodes (seven), lung (two), liver (one), and spleen (one). There were four men
`and five women aged 46—75 years. Toxicities included myalgia, arthralgia,
`hypoalbuminemia, fatigue, elevations in liver function tests, and increased
`peripheral edema. Four patients received two to five repeated dosages of
`XMMME—OOl-RTA. One wheal-and-flare reaction from an immunotoxin test
`dose of XMMME-OOl-RTA was noted after five cycles. After a test dose sub—
`sequent to one cycle, two patients experienced chest tightness without ECG
`changes and were removed from the study. All toxicities resolved without
`sequelae. One patient experienced partial lymph node remission for 9 months.
`A second patient had stable mediastinal disease for 20 months. XMMME-OOI-
`RTA is safe when given repeatedly with cyclosporine. Key Words: Immuno-
`conjugates—Ricin A—Cyclosporine A—Melanoma.
`
`XOMAZYME-Mel (XMMME-OOl-RTA) is an
`immunoconjugate comprised of an IgG2a murine
`monoclonal antibody directed against high molecu-
`lar weight antigens of human melanoma and conju-
`
`Received June 1, 1992; accepted November 20, 1992.
`Address correspondence and reprint requests to Dr. K.
`Selvaggi at Division of Hematology, Department of Medicine,
`Pittsburgh Cancer Institute, University of Pittsburgh, Pittsburgh,
`PA 15213, U.S.A.
`
`gated to the A chain of ricin. Ricin, a natural prod-
`uct of beans from the plant Ricinus communis, is an
`extremely potent inhibitor of protein synthesis and
`will cause cell death. It is composed of two chains.
`The A chain is able to inhibit protein synthesis,
`while the B chain mediates binding to the cell sur-
`face (1).
`Spitler et a1. (2) conducted a Phase I trial using
`intravenous administration of XOMAZYME-Mel in
`
`201
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`202
`
`K. SELVAGGI ET AL.
`
`22 patients with metastatic melanoma. The dose of
`immunoconjugate administered ranged from 0.01
`mg/kg for 5 days to 1 mg/kg for 4 days. Toxicities
`including fatigue, myalgia, malaise, fever, and de—
`crease in appetite were dose related and generally
`transient and reversible. The major dose—limiting
`side effect of the immunoconjugate was a fall in
`serum albumin with resultant weight gain and third-
`space fluid shifts. The fall in serum albumin was
`observed in all patients receiving at least 0.2 mg/kg/
`day of immunoconjugate (2). Immunological analy-
`sis indicated that all patients mounted a distinct
`host antibody response to the murine immunoglob-
`ulin and the ricin A chain component of the immu-
`noconjugate following completion of therapy. There
`was no relationship of toxicities to immune re-
`sponse. Other studies have also shown formation of
`anti-immunoconjugate antibodies after one or more
`infusions of immunoconjugate therapy (3—5).
`Cyclosporine A, a potent immunosuppressive
`agent that inhibits T-cell proliferation and lympho-
`kine production,
`is also an inhibitor of B-cell
`proliferation and immunoglobulin production (6—8).
`Ledermann et a1. (9) showed that the anti-immuno—
`conjugate response to repeated infusions of mouse
`monoclonal antibodies in rabbits was prevented by
`cyclosporine A. In a follow-up report, Ledermann
`et al. (10) showed that cyclosporine A was able to
`suppress an immune response in patients treated
`with radiolabeled antibody to carcinoembryonic an—
`tigen. Up to four times as many doses of antitumor
`antibody could be given without a host antibody
`response when cyclosporine A was used. Treat-
`ment was repeated for up to four doses if anti—
`immunoconjugate antibody values remained below
`6 ug/ml.
`Recently, Oratz et al. (11) treated 20 melanoma
`patients on a Phase II protocol with XOMAZYME-
`Mel plus cyclophosphamide in an effort to block the
`anti—immunoconjugate response and enhance anti-
`tumor response. Although there was no decrease in
`the anti-immunoconjugate response against either
`the murine antibody or the ricin moiety with the use
`of cyclophosphamide, there was no decrease in ef—
`ficacy. An overall anti-tumor response rate of 20%
`was observed primarily in pulmonary and soft tis-
`sues metastases.
`
`The study reported here sought to evaluate fur-
`ther the immune response to XOMAZYME-Mel im-
`munoconjugate in the presence of cyclosporine and
`to evaluate the safety and efficacy of repeated
`courses of immunoconjugate.
`
`J Immunother, Vol. 13, No. 3. 1993
`
`MATERIALS AND METHODS
`
`Patients
`
`Nine patients were entered into this study. All
`nine were evaluable, but due to a clerical error (pa-
`tient 001 was reassigned no. 006), the patients were
`numbered 002—010. There were four men and five
`
`women with ages ranging from 46 to 75 years (me-
`dian 64 years). Each had a documented history of
`metastatic melanoma and had received no antineo-
`
`plastic therapy with biological agents, chemother-
`apy, or investigational drugs within 4 weeks prior to
`study entry. Seven patients had metastatic disease
`in the soft tissue, skin, and/or lymph nodes, one
`patient had liver metastases, one patient had splenic
`metastases, and two patients had metastases to the
`lung. No patients had received murine monoclonal
`antibodies or had a known hypersensitivity to ro-
`dent material. All patients had a Karnofsky perfor—
`mance status of 80—100% with an expected survival
`time of >3 months, white count of 23,500/mm3,
`platelet count of 2100,000/mm3, and adequate renal
`and liver function as determined by a serum creat-
`inine level $1.5 times normal and a bilirubin level
`
`S2 times normal, respectively. Serum glutamic-
`oxaloacetic transaminase and alkaline phosphatase
`levels were $1.5 times normal. Patients had no se-
`
`vere systemic disease aside from melanoma. The
`study was approved by the University of Pittsburgh
`Internal Review Board, and a signed informed con-
`sent was obtained from each patient prior to study
`entry.
`
`Cyclosporine
`
`Cyclosporine A (Sandoz, East Hanover, NJ,
`USA.) was begun on day 1 of the first cycle at an
`initial dose of 15 mg/kg/day as two divided oral
`doses (7.5 mg/kg/dose p.o. b.i.d.). Cyclosporine A
`doses were adjusted to achieve trough whole-blood
`cyclosporine concentrations between 150 and 200
`ng/ml by HPLC and continued through day 22 of
`each cycle. Patients remained on the cyclosporine
`dose that achieved trough whole-blood cyclospor-
`ine concentrations between 150 and 200 ng/ml in the
`previous cycle for all subsequent courses. Blood
`samples were obtained daily until cyclosporine con-
`centrations were stable within the desired range,
`and then obtained weekly, during the duration of
`cyclosporine A administration. Patients maintained
`medication diaries to document self-administered
`
`IMMUNOGEN 2312, pg. 2
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`|PR2014—00676
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`

`XOMAZ YME—MEL IMM UN0CONJ UGATE AND C YCLOSPORINE A
`
`203
`
`cyclosporine doses and times of drug administra-
`tion. Cyclosporine was extracted from whole blood
`and analyzed by an HPLC method described by
`Ptachcinski et a1. (12).
`
`Immunoconj ugate
`
`The immunoconjugate (XMMME-OOl-RTA)
`comprised of an IgG2a murine monoclonal antibody
`directed against high molecular weight antigens of
`human melanoma conjugated to the A chain of ricin
`was produced by XOMA Corp. (Berkeley, CA,
`USA.) (13). The conjugation technique has been
`described in previous articles (2,13). The ricin A
`chain was purified by affinity chromatography using
`an anti-ricin B chain column. The antibody was ac-
`tivated with N-succinimidyl-3-(2—pyridylditheo)pro—
`pionate followed by addition of affinity-purified ri-
`cin A chain that was reduced with dithiothreitol.
`
`The immunoconjugate was then purified by gel
`chromatography, and specificity was confirmed by
`enzyme-linked immunosorbent assay. It was sup-
`plied as a sterile solution of 1 mg/ml in phosphate-
`buffered saline with a pH of 7 and was stored at
`2—8°C.
`
`Protocol
`
`To evaluate immediate-type hypersensitivity
`prior to each cycle of therapy, each patient was skin
`tested by intradermal injection of 10 pg of the im—
`munoconjugate. The patient was observed for 30
`min. If the patient developed a wheal of >5 mm, the
`study was terminated. If the patient had a negative
`skin test, an intravenous challenge dose of 0.2 mg
`was administered. The patient was observed for 30
`min before the full dose was administered.
`
`Patients received cyclosporine A in divided daily
`doses to achieve trough whole-blood cyclosporine
`concentrations of 150—200 ng/ml on days 1—22
`(HPLC). Starting on day 4, the immunoconjugate
`was administered intravenously over 60 min once
`daily for 5 days. Treatment was repeated every 35
`days until disease progression was noted, until the
`patient developed an allergic reaction to
`XOMAZYME-Mel (defined as a fall in blood pres-
`sure of >20 mm Hg, a pulse of >120 beats/min, a
`temperature of >101°F, respiratory distress, or se—
`vere systemic immediate-type hypersensitivity re—
`
`action such as generalized urticaria), or until the
`recurrence of grade IV toxicity. Three patients
`were treated in each dosage tier (0.2, 0.4, and 0.6
`mg/kg/day) for a total of nine patients.
`The patients were evaluated by physical exami-
`nation and laboratory studies including chemistry
`panel, hematology panel, chest x-ray film, ECG,
`computerized tomography (CT) of the head and ab-
`domen, urinalysis, and coagulation panel. The IgG
`immune response to the whole immunoconjugate
`was determined prior to treatment and on days 4, 8,
`and 35. Immunoconjugate pharmacokinetic samples
`were obtained prior to infusion and 30, 60, 75, and
`90 min and 2, 4, 6, 8, and 12 h after infusion began
`on days 4 and 8.
`
`Immunoconjugate Level and Antibody
`
`Measurement of Immunoconjugate in
`Human Serum
`
`Serum samples were incubated with MINOR
`cells, a human melanoma cell line (supplied by Dr.
`B. C. Giovanella, Houston, TX, U.S.A.), fixed to
`microtiter plates. Bound immunoconjugate was de-
`tected using goat anti-ricin A chain and alkaline
`phosphatase—conjugated rabbit anti-goat IgG. The
`color was developed using p-nitrophenyl phosphate
`in a diethanolamine buffer, and the optical density
`at 405 nm was determined. Samples were quantified
`in reference to a standard curve. The detection limit
`
`was 0.08 ug/ml.
`
`Measurement of Anti—Immunoconjugate in
`Human Serum
`
`Antibody response to whole immunoconjugate
`was measured in all patients (Table 1). Several di-
`lutions of each sample were incubated with the im-
`munoconjugate adsorbed to microtiter plates.
`Bound antibody was detected using alkaline phos-
`phatase-conjugated goat anti-human IgG antibod-
`ies. The color was developed using p-nitrophenyl
`phosphate in a diethanolamine buffer and the absor-
`bance at 405 nm was determined. The endpoint titer
`was determined from the intersection of the linear
`
`portion of the absorbance versus dilution curve for
`each sample with the 0.200 absorbance line. Im-
`mune responses were expressed as a response ratio:
`the ratio of the endpoint titer of the serum sample
`
`J Immunother, Vol. 13, No. 3, 1993
`
`IMMUNOGEN 2312, pg. 3
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`204
`
`K. SELVAGGI ET AL.
`
`TABLE 1. Anti-immunoconjugate antibody titers
`
`Dose of
`immuno-
`conjugate
`(mg/kg)
`
`Patient
`no.
`
`Cycle
`no.
`
`Day 35 IgG
`endpoint
`titer“
`
`Response
`ratio”
`
`002
`003
`
`004
`005
`006
`007
`
`008
`009
`
`010
`
`0.2
`0.2
`
`0.2
`0.4
`0.4
`0.4
`
`0.6
`0.6
`
`0.6
`
`31
`1
`260
`1
`4,800
`2
`3,800
`3
`1,300
`4
`—
`5
`—
`1
`470
`1
`430
`1
`16
`1
`780
`2
`11,000
`3
`1,400
`1
`490
`1
`8,700
`2
`6,100
`3
`210
`1
`2,900
`290,000
`2
`3,600
`360,000
`3
`3,000
`300,000
`4
`
`
`NA5 —
`
`66,000
`26,000
`480,000
`380,000
`130,000
`NA
`NA
`47,000
`43,000
`1,600
`78,000
`1,100,000
`140,000
`49,000
`870,000
`610,000
`
`from the date of therapy until the date of progres-
`sive disease or death.
`
`Toxicity
`
`Toxicities were defined using the NIH common
`toxicity scale.
`
`RESULTS
`
`Toxicity
`
`Table 2 details the number of treatment courses
`
`given to each patient within each dose tier and the
`severity of the toxicities. All patients were evalu-
`able for toxicity. The severity of the toxicities was
`not significantly related to the increase in the dos—
`age of the immunoconjugate or to the number of
`cycles of immunoconjugate given. Grade I and II
`toxicities were present in all dosage tiers. These
`included myalgia, arthralgia, diarrhea, decreased al-
`bumin, increased peripheral edema, nausea, hy-
`potension, fatigue, and anorexia and elevations in
`blood urea nitrogen and creatinine and liver func-
`tion tests. One of nine patients developed grade III
`hypotension (>40-mm Hg drop in blood pressure or
`severe postural change), which was treated with in-
`travenous normal saline with resolution. Five pa-
`tients developed grade III myalgia and arthralgia
`that resolved with analgesics. One of these five pa—
`tients also developed grade III fatigue and anorexia.
`These resolved without further therapy. Three pa-
`tients experienced possible allergic reactions. One
`patient was limited to five cycles due to a wheal-
`and-flare reaction to the intradermal immunoconju-
`gate test dose prior to starting cycle 6. Two other
`patients developed symptoms during the intrave-
`nous test dose; prior to cycle 2, both developed
`chest tightness without ECG changes. Chest x-ray
`films were normal. There was no evidence of peri-
`
`TABLE 2. Number of patient cycles per dosage tier
`and occurrences of toxicity
`
`Dose of
`immuno-
`conjugate
`(mg/kg)
`
`Grade
`Cycle
`-————-—~— ——
`1
`2
`3
`4
`5
`I
`II
`III
`IV
`
`0
`3
`9
`13
`1
`1
`1
`1
`3
`0.2
`0
`3
`10
`13
`0
`0
`1
`l
`3
`0.4
`
`
`
`
`
`
`
`
`
`3 2 2 l 1 10 5 20.6 0
`
`IMMUNOGEN 2312, pg. 4
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`|PR2014-00676
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`NA, not assayed.
`“ Specified day 35 (range 33—42 days) of designated cycle.
`5 Response ratio: endpoint titer of day 35 (of designated cycle)
`divided by that of cycle 1 pretreatment (pretreatment titer for
`patient 002 = 2,100; all others = 100).
`
`on a particular day to the endpoint titer of the pre—
`treatment serum sample. An analytically positive
`immune response was defined as a 10-fold increase
`in titer from cycle 1 pretreatment levels.
`
`Tumor Response
`
`Tumor response was defined in terms of complete
`response, partial response, minimal response, sta-
`ble disease, or progressive disease. Complete re-
`sponse represented the disappearance of all mea-
`surable disease determined by two observations not
`<4 weeks apart, while partial response represented
`a reduction of >50% in the sum of all measurable
`
`disease without new lesions or enlargement of any
`previous lesions during the same time frame. A case
`was classified as minimal response if there was a
`reduction by 25—50% in measurable disease without
`new lesions or enlargement of any previous lesion
`by two observations >4 weeks apart. Stable disease
`was defined as <25% decrease in measurable dis-
`
`ease without new lesions or enlargement of previ-
`ous lesions. Appearance of new lesions or enlarge-
`ment of previous lesions was classified as progres-
`sive disease. The duration of response was defined
`
`J Immunother, Vol. 13, No. 3, 1993
`
`IMMUNOGEN 2312, pg. 4
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`

`XOMAZ YME-MEL IMMUNOCONJUGATE AND CYCLOSPORINE A
`
`205
`
`cardial effusions or changes in ventricular function.
`Levels of creatinine phosphokinase did not in-
`crease. Symptoms subsequently resolved and both
`patients were discontinued from the study. No
`grade IV toxicity occurred.
`
`Clinical Response
`
`There were no complete responses to treatment.
`Patient 010 had a partial response of lymph node
`metastases for 9 months after five cycles of therapy.
`This was documented by chest x-ray film and chest
`CT scans. Another patient (005) had prolonged sta-
`ble mediastinal disease for 20 months after one cy—
`cle of therapy, but had concomitant increased size
`and number of vaginal lesions in the area of prior
`tumor resection requiring additional resections. Her
`disease subsequently progressed in the mediasti-
`num, requiring further treatment. Six patients (002,
`003, 004, 006, 007, 009) developed progression of
`disease and therefore were discontinued from the
`
`study. Patient 008 was discontinued from the study
`after cycle 1 due to chest tightness during the intra-
`venous test dose prior to cycle 2.
`
`Immune Responses
`
`An immune response during the first cycle was
`evaluable in eight of nine patients. This response
`was present in all eight patients (Table 1). It in-
`creased in four of four patients during the second
`cycle. In the third cycle there was either a decrease
`or no significant increase in response in three of
`four patients. This trend continued in two of two
`patients during cycle 4. No complete data sets were
`obtained during cycle 5 . Figure 1 shows the kinetics
`of the antibody response for three patients, one in
`each dosage tier.
`The dose of cyclosporine used in this study did
`not prevent the production of anti-immunoconju-
`gate antibodies.
`
`Pharmacokinetics
`
`Table 3 gives selected pharmacokinetic data of
`the immunoconjugate for three patients, one in each
`dosage tier. Terminal half-lives of the immunocon-
`jugate ranged from 2.03 to 2.98 h. In one patient the
`terminal half—life was obtained from three cycles.
`
`+ 003
`—0— 007
`-—I—— 010
`
`100000
`
`10000
`
`1000
`
`100
`
`10
`
`
`
`(titer:pretreatmenttiter)
`
`Ratlo
`
`4635463548354835
`Day wlthln Cycle
`
`1
`
`2 Cycle
`
`3
`
`4
`
`Immune response, as measured by titer relative to pre-
`FIG. 1.
`treatment titer, increased during the first and second cycle and
`reached a higher maximum response during the second cycle as
`compared with the first. This trend continued for one patient
`(007) during the third cycle; however, no decrease or significant
`increase in titer occurred in two patients (003, 010) during the
`third and fourth cycles.
`
`DISCUSSION
`
`This study assessed the safety and efficacy of cy-
`closporine administered in conjunction with an anti-
`melanoma-associated antigen immunoconjugate in
`a 5-day multicycle regimen. The study was designed
`as an attempt to block the human anti-immunocon-
`jugate response to allow for repetitive dosing of the
`immunoconjugate. Humoral immune response to
`the anti-melanoma—associated antigen immunocon-
`jugate was measured over time to determine the
`immunosuppressive efficacy of cyclosporine.
`The maximum tolerated dose (MTD) defined as
`the dose of immunoconjugate above which more
`than half of the patients experienced grade III or IV
`toxicity was never reached during the trial. Initial
`trials of this anti-melanoma—associated antigen im-
`munoconjugate used a similar schedule of adminis-
`tration and found the MTD to be 0.5 mg/kg. Dose-
`limiting toxicity was related to hypoalbuminemia
`and fluid retention (2). More recently, Gonzalez et
`a1.
`(14) found that the maximum tolerated single
`dose of .XOMAZYME-Mel was 1.25 mg/kg. Dose-
`limiting toxicity was due to myalgias, arthralgias,
`and fatigue (14).
`In the present study we were able to administer
`immunoconjugate at a dose of 0.6 mg/kg without
`significant toxicity. Within the first 16 days follow-
`ing treatment, hypoalbuminemia was noted in five
`patients. This was manifested by a serum albumin
`level of between 2.5 and 3.0 g% in three patients
`
`J Immunother, Vol. 13, No. 3, 1993
`
`IMMUNOGEN 2312, pg. 5
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`|PR2014—00676
`
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`

`206
`
`K. SELVAGGI ET AL.
`
`TABLE 3. Peak immunoconjugate concentration and half-life of immunoconjugate in selected patients at
`various cycles
`
`Patient no.
`
`Dosage tier
`(mg/kg/day)
`
`003
`007
`010
`
`0.2
`0.4
`0.6
`
`Peak concentration (pg/ml)“"’
`
`Terminal half-life (h)
`
`Cycle 1
`
`Cycle 2
`
`5.33
`11.43
`14.90
`
`NA
`6.07
`0.10
`
`Cycle 3
`
`<0.08
`1.79
`<0.08
`
`Cycle 1
`
`Cycle 2
`
`Cycle 3
`
`2.24
`2.98
`2.24
`
`—
`2.03
`—
`
`——
`2.55
`—
`
`NA, not assayed.
`One compartment (monoexponential) model, PCNONLIN.
`b Detection limit 0.08 ug/ml.
`
`with grade I toxicity and between 2.0 and 2.5 g% in
`two patients with grade II toxicity. All five patients
`developed mild to moderate peripheral edema,
`three of whom were treated with furosemide. The
`
`differences in toxicity observed between this and
`the previously reported study may be related to sta-
`tistical methods of defining MTD, with a resultant
`lower estimate of the actual MTD in the previous
`study. On the other hand,
`immunosuppressive
`agents may have influenced the magnitude of tox-
`icity. Possible mechanisms of this interaction in-
`clude protein inhibition (cyclophosphamide),
`change in kidney function (cyclosporine), and direct
`immunosuppression.
`Cyclosporine A is a potent inhibitor of B-cell pro-
`liferation and immunoglobulin production. How-
`ever, in this study cyclosporine levels of 150—200
`ng/ml given for 22 consecutive days did not prevent
`anti-immunoconjugate response in any of the three
`dosage tiers. Increasing the levels of cyclosporine
`was not possible due to the nephrotoxic potential of
`this drug.
`Other investigators studying XOMAZYME-Mel
`have evaluated the effects of other immunosuppres-
`sive regimens such as cyclophosphamide (11,15,
`16). Patients receiving azathioprine and prednisone
`combinations had more immunosuppression of the
`anti-immunoconjugate antibodies than those receiv-
`ing moderate-dose cyclophosphamide and pred-
`nisone, but suppression of the immune response
`was achieved with high-dose cyclophosphamide
`alone.
`
`Extensive evaluation of the pharmacokinetics of
`the immunoconjugate was not possible because of
`the limited number of patients. Based on the eval-
`uation of patients 003, 007, and 010, there is a cor-
`relation between the extent of the anti-immunocon-
`
`jugate response and the fall in circulating peak con-
`centrations of immunoconjugate. This did not affect
`the magnitude of the terminal half-life. It is possible
`
`JImmunother, Vol. 13, No. 3, 1993
`
`that the reduction in the peak serum levels of the
`immunoconjugate in later treatment cycles might be
`due to interference with the assay itself by the anti-
`immunoconjugate antibodies,
`increased initial
`clearance of the immunoconjugate secondary to the
`presence of these antibodies, the presence of anti-
`body-immunoconjugate complexes (which might
`still have anti-tumor activity) not detectable by the
`assay, or any combination of the above.
`In this study two patients had either a partial re-
`sponse or prolonged stable mediastinal disease (9
`and 20 months, respectively) at dosages of 0.4 and
`0.6 mg/kg/day, respectively. We cannot comment
`on the effectiveness of the immunoconjugate at
`higher dosages, but perhaps immunoconjugate-
`cyclosporine combinations may allow for dose in-
`tensification of immunoconjugate with resultant in-
`creased effectiveness. Further evaluation of this
`
`speculation is warranted.
`In summary, the primary toxicities encountered
`during this study were grade I and II. No grade IV
`toxicity occurred. Toxicities did not significantly in-
`crease with an increase in the dosage of the immu-
`noconjugate or in the number of cycles. Although
`anti-immunoconjugate response was noted in all pa-
`tients, there appeared to be no influence on toxici—
`ties. Due to possible allergic responses to the test
`dose, two patients just prior to the second cycle and
`one patient just prior to the fifth were discontinued
`from the study. Their symptoms and signs subse-
`quently resolved. Overall, multiple courses of the
`immunoconjugate with cyclosporine can be admin-
`istered safely.
`In conclusion, we found the combination of
`XOMAZYME-Mel immunoconjugate and cyclo-
`sporine to be well tolerated. Effective suppression
`of the anti-immunoconjugate antibody response
`was not achieved at the dosage and schedule of ad-
`ministration in this study, but this did not lead to
`adverse reactions not did it appear to affect effi-
`
`IMMUNOGEN 2312, pg. 6
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`IMMUNOGEN 2312, pg. 6
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`

`XOMAZ YME-MEL IMM UN0CONJUGATE AND C YCLOSPORINE A
`
`207
`
`cacy. More extensive clinical trials at higher doses
`to reach MTD remain to be performed.
`
`is a registered
`Acknowledgment: XOMAZYME—Mel
`trademark of XOMA Corp. We thank Denise Williams for
`her assistance in the preparation of the manuscript.
`
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