Immunotherapy for renal carcinoma: theoretical basis and current
`standard of care
`
`Paul A. Vasey
`
`CRC Department of Medical Oncology, University of Glasgow, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD
`
`Introduction
`
`Carcinoma of the kidney (a.k.a. ‘hypernephroma’ or renal
`cell cancer) accounts for 2–3% of all adult cancers, and
`over 4000 new cases are reported in the UK every year [1].
`It occurs more commonly in men, and has a peak
`incidence around 60–70 years, although can occur at any
`age. The incidence is increasing [2]. If confined to the
`kidney, surgical resection is the treatment of choice, and
`cure can result. However, most patients with metastatic
`disease survive less than 1 year [3], and chemotherapeutic
`or hormonal approaches are generally ineffective.
`The natural history of renal cancer characteristically
`manifests an indolent course, with long periods of stable
`disease.
`In addition,
`the ‘spontaneous
`regression’ of
`metastases has often been reported in the literature, and
`Evenson & Cole [4] made the observation that renal
`cancer appeared to have the highest incidence of this
`controversial and intriguing phenomenon. The actual
`frequency of spontaneous regression in renal tumours is
`not known, but estimates put it at around 0.3% [5]. A
`higher frequency has been reported following nephrect-
`omy in patients with established metastatic disease [6]. The
`existence of spontaneous regression has been put forward
`as evidence that a form of
`innate ‘host
`factor’ or
`immunological response may be involved in its pathogen-
`esis. Such a hypothesis is supported by the increase in renal
`cancer cases observed in patients receiving long-term
`immunosuppressive therapy for organ transplantation [7].
`
`The immune response
`
`The ‘immune surveillance’ hypothesis was first conceptual-
`ized at the beginning of the century by Paul Ehrlich. He
`suggested that the malignant transformation of a cell was a
`frequent occurrence, and that the transformed ‘rogue’ cells
`were recognized as foreign to the body and destroyed by
`
`Correspondence: Dr P. A. Vesey, CRC Department of Medical Oncology,
`University of Glasgow, Garscube Estate, Switchback Road, Bearsden, Glasgow
`G61 1BD.
`
`Received 28 July 1999, accepted 13 September 2000.
`
`transformed cells
`immune system. In this model,
`its
`develop into overt tumours as a consequence of either
`somehow losing their immunogenicity, or because of a
`defect in the host’s immune system. Such an elegant and
`simple hypothesis has been difficult to substantiate; it has
`been observed that nude mice (lacking a thymus and
`therefore immunodeficient) do not appear to be more
`susceptible to cancers
`than immunocompetent mice.
`Furthermore, the majority of malignancies developing in
`organ transplant patients receiving immunosuppressants
`like cyclosporin involve the immune system, and do not
`generally manifest as the more common solid tumours.
`Despite these caveats, it can be demonstrated that a host
`immune response is produced and directed against tumour
`cells, although is often ineffective. The generation of a co-
`ordinated immune response to an antigenic stimulation
`like cancer
`is extremely complex and requires
`the
`interaction of several cell types. Figure 1 outlines the
`essential components and interactions of
`the human
`immune response; for a more detailed description, the
`reader is referred to Kuby [8]. In the humoral response, the
`TH cell
`(lymphocytes displaying the CD4 membrane
`glycoprotein; helper T-lymphocytes)
`interacts with an
`antigen committed B-lymphocyte, which has presented its
`antigen on the cell membrane (via endocytic processing)
`to the TH cell in association with a class II MHC (major
`histocompatibility complex) molecule. Secretion of a
`number of cytokines by the TH cell, including IL-2, IL-4,
`IL-5, IL-6, and interferon-c then occurs. Cytokines are
`low molecular weight proteins which bind with very high
`affinity to specific target cell receptors, eliciting biochem-
`ical changes responsible for signal transduction that results
`in an altered pattern of gene expression in the target cells.
`These cytokines have the effect of stimulating differentia-
`tion and proliferation of
`the B-lymphocyte into B-
`memory lymphocytes, and into plasma cells which secrete
`antibody. Following TH cell interaction with an antigen –
`class II MHC molecule on an antigen presenting cell, the
`cytokine IL-2 is secreted and binds to a newly expressed
`receptor on the TH cell.
`In this
`situation,
`such
`autostimulation results in proliferation and clonal expan-
`sion of TH cells, which are specific for the initiator antigen.
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`P. A. Vasey
`
`Cell-mediated response
`
`Tumour
`antigen
`
`Humoral response
`
`‘Antigen processing’
`
`B-cell
`
`+ antigen
`presenting cell
`
`TH interaction
`and IL-2 (etc)
`stimulation
`
`Exogenously
`processed within
`cytoplasm
`
`Exogenously
`processed by
`endocytosis
`
`differentiation
`
`Memory B-cell
`
`Activates and clonally expands
`
`Plasma cell
`
`Recognised by
`
`Class II
`MHC
`
`Secreted antibody
`
`T-Helper
`
`Class I
`MHC
`
`T-cytotoxic
`
`produces
`
`autostimulates
`
`IL-2
`(+other cytokines
`IL-4, IL-5, IL-6,
`interferon-gamma)
`
`Antigen elimination
`by secreted antibodies
`
`Cytotoxic T lymphocyte
`(CTL)
`
`Direct cell killing
`by lysis
`
`CTL
`
`Altered self
`cell
`
`Figure 1 Overview of the humoral and cell-mediated immune response.
`
`The activated TH cells are then crucial in the generation of
`both humoral and cell mediated responses.
`In the cell-mediated response, the presence of IL-2
`secreted by the TH cells induces TC cells (cells displaying
`CD8; cytotoxic T-lymphocytes) into becoming cytotoxic T
`
`(CTLs) which are able to mediate cell
`lymphocytes
`membrane damage and lysis to altered self cells. Other
`secreted cytokines enable the differentiation of a number
`of other nonspecific effector cells. IL-2 and interferon-c
`activate macrophages,
`thus enhancing the phagocytic
`
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`ingested pathogens and
`these cells against
`activity of
`tumour cells. These cytokines also enhance the activity of
`the natural killer (NK) cell.
`There are several types of cancer for which the approach
`to treatment involves augmentation or supplementation of
`the natural defence mechanisms described above. How-
`ever, the complexity of the cytokine network makes it
`very difficult to know precisely how intervention with a
`specific cytokine may affect
`the production of other
`cytokines, as there are demonstrated antagonistic as well as
`synergistic relationships within this network. In metastatic
`renal cancer, treatment with purified human leucocyte
`interferon-a (IFA), was reported to have antitumour
`effects in the early 1980s [9]; however, it was not until the
`various cytokine genes were cloned before large-scale
`production and sizeable clinical trials were possible.
`
`Interferon-a (IFA)
`
`Although large quantities of purified recombinant
`interferons a, b,
`and c are
`preparations of
`the
`commercially available, most clinical
`trials
`in renal
`cancer have involved IFA. Given by subcutaneous
`injection,
`the dose of IFA is
`limited by side-effects
`which involve many organ systems,
`in addition to
`toxicities thought to be specific to the immune system.
`An acute phase of
`toxicity occurs
`in the immediate
`postinjection period and may consist of
`fevers/chills,
`nausea, myalgia/arthralgia
`and malaise. Attempts
`to
`abrogate these toxicities
`include premedication with
`paracetamol or nonsteroidal
`anti-inflammatory drugs
`(NSAIDs) such as ibuprofen. Toxicities associated with
`chronic administration consist of
`fatigue,
`anorexia,
`weight loss, depression, lack of concentration, diarrhoea,
`low blood pressure and mild haematological and hepatic
`abnormalities. Very high doses (up to 100 000 mega
`units (MIU)) have been shown to be profoundly toxic
`and can be fatal, but such doses are not required to
`achieve therapeutic benefits. Most patients currently
`treated with IFA for metastatic renal cancer receive
`3–10 MIU,
`thrice weekly by subcutaneous injection.
`IFA is currently licensed in the U.K. for use in a variety
`of malignancies.
`Prior to randomised trials, the overall response rates
`(incidence of observed tumour regression) to IFA in renal
`cancer were reported to be of the order 10–12%, with
`complete responses observed in less than 2% of patients
`[10]. Responses were slow to develop, and were seen most
`frequently in patients having had a nephrectomy, and who
`were relatively fit with few metastatic sites (lung metastases
`being the ‘best’ site). In a group of 159 nonrandomised
`patients treated with IFA in a single cancer centre, median
`survival was reported as 11.4 months [11].
`Data from randomised trials in renal cancer are required
`
`Immunotherapy for renal carcinoma
`
`to fully evaluate the possible advantages of IFA, and it is
`particularly important to compare with no treatment (or
`‘best supportive care’) in renal cancer, given the potential
`for side-effects. The first reported randomised study did
`not actually demonstrate an advantage for IFA over a
`relatively nontoxic hormonal therapy (medroxyprogester-
`one acetate; MPA) [12]. However, this trial was small (60
`patients total) and was not empowered to make any
`significant statistical comparisons between the two treat-
`ments. In addition, 15/30 patients receiving MPA crossed
`over to IFA following the development of progressive
`disease.
`A larger trial in metastatic renal cancer randomised 197
`patients to receive either interferon-c or placebo injections
`[13]. Interferon-c was chosen because of laboratory data
`which hinted at greater activity for this cytokine than
`either IFA or interferon-b. However, this trial found no
`significant difference in survival
`for patients receiving
`interferon-c, when compared with placebo. Once again
`though, it was not large enough to detect small, potentially
`significant differences in survival. In addition, previous
`smaller nonrandomised trials had also failed to hint at a
`clinically relevant advantage for interferon-c; Wirth [10]
`reported a response rate of 12% culled from 234 patients
`over four separate trials.
`from the MRC (trial RE01)
`A recent pivotal trial
`compared IFA and MPA in 335 patients with metastatic
`renal cancer [14]. Here, patients were randomised to
`receive IFA 10 MIU thrice weekly for 12 weeks by
`subcutaneous injection, or MPA 300 mg dayx1 for the
`same duration. A survival advantage for IFA (1 year
`survival 43% vs 31%, median survival 8.5 months vs
`6 months) was seen which translated into a 28% reduction
`in the risk of death (hazard ratio 0.72; 95% CI 0.55–0.94,
`P=0.017). Although side-effects were more common in
`patients receiving IFA,
`these differences were not as
`obvious at the end of the 12 week treatment period, which
`may suggest
`that patients
`adapt
`and develop im-
`proved tolerance to chronically administered immuno-
`therapy.
`Similar improvements in progression-free survival for
`IFA have also been reported by Pyrhonen and colleagues
`[15] who randomised 160 patients to receive either IFA in
`combination with vinblastine (a cytotoxic agent), or to
`treatment with vinblastine alone. Prior experience with
`vinblastine has shown very low activity in renal cancer, in
`common with most other cytotoxics [16], and therefore
`the control arm here could be considered as little more
`than placebo. The results of these two studies suggest that
`IFA has a beneficial effect on survival for metastatic renal
`cancer when compared with placebo. However,
`this
`increased survival due to immunotherapy needs to be
`weighed against the side-effects and subsequent detri-
`mental effect on the patients’ quality of life.
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`P. A. Vasey
`
`Interleukin-2 (IL-2)
`
`Recombinant interleukin-2 (rIL-2) was first produced in
`1983 [17], and was subsequently found to be a potent
`immunostimulant. Significant responses were observed in
`selected human tumours
`[18] and laboratory studies
`suggested that a dose–response relationship existed [19].
`Because of this, the initial clinical trials used high-dose
`intravenous bolus administration schedules.
`A 255-patient database of renal cancer patients treated
`with rIL-2 in seven phase II studies submitted to the U.S.
`Food and Drug Administration (FDA) has recently been
`updated [20]. In these studies, patients received 0.6 or 0.72
`MIU kgx1 rIL-2 by 15 min bolus infusion every 8 h for
`up to 14 consecutive doses over 5 days. Patients tolerating
`this
`treatment could receive further courses of rIL-2
`following rest periods. Overall, antitumour efficacy was
`very encouraging, with an overall response rate of 15%,
`and complete responses
`seen in 7%. However,
`the
`duration of such responses was the most encouraging
`feature, with a median response duration of 54 months
`(range 3–104+), and complete responses lasting for a
`median of 20 months (range 3–97+). Median survival for
`the group as a whole was 16.3 months. The earlier results
`of these studies were used to gain FDA approval in 1992
`for the use of rIL-2 in the treatment of metastatic renal cell
`cancer in the USA.
`Unfortunately, bolus intravenous administration was
`found to be associated with severe toxicity. Many of the
`side-effects
`seen were unexpected, and unlike those
`observed with conventional chemotherapy. A capillary
`leak syndrome resulted in a variety of
`serious,
`life-
`threatening conditions such as pulmonary oedema, multi-
`organ failure, and renal/hepatic dysfunction. Fatalities
`were not uncommon, and many patients became critically
`ill, requiring intensive care nursing. Despite this, clinicians
`were sufficiently encouraged by both the complete
`responses observed and the relatively long duration of
`such responses, and ways to abrogate these side-effects
`became an important objective.
`Administering rIL-2 by continuous intravenous infu-
`sion seems to reduce the need for intensive care support
`during treatment, without negatively impacting on the
`durability of remissions [21]. However, this approach has
`not been directly compared with intravenous bolus
`therapy, and there is some data suggesting that rIL-2
`should not be delivered by continuous infusion because of
`inactivation in the giving set tubing [22].
`The use of lower intravenous bolus doses has been the
`subject of a prospective, randomised trial, which is not yet
`mature enough for definitive conclusions to be made
`regarding survival
`[23)]
`In this
`study, patients were
`randomised to receive 0.72 or 0.072 MIU kgx1 rIL-2
`by 15 min bolus injection, 8 hourly. With 116 and 112
`
`patients randomised in each arm, significantly less toxicity
`was experienced by patients
`in the low-dose arm.
`However, there is a suggestion that the high dose arm is
`associated with a superior short-term response rate (19% vs
`10%). Longer-term follow-up may reveal
`if
`these
`differences are significant.
`schedules have been
`A number of
`subcutaneous
`developed to deliver low doses (0.8–6 MIU dayx1) of
`IL-2 [24–27]. Similar preclinical
`immunomodulatory
`effects have been demonstrated with both subcutaneous
`and intravenous low-dose IL-2. Studies indicate that the
`chronic administration of low-dose rIL-2 induces anti-
`tumour immunomodulatory effects comparable with those
`obtained with high-dose rIL-2 with a significant decrease
`in systemic toxicity [24]. The definitive dose of ‘low-dose’
`rIL-2 is unclear, but is now generally accepted to be less
`than 6 mIU dayx1.
`In another approach to rIL-2 therapy, Huland and
`coworkers reported the experience of 116 patients with
`pulmonary or mediastianal metastases from renal carci-
`noma treated with inhaled IL-2 [28]. Toxicity was
`minimal, consisting mainly of cough, despite the high
`doses (up to 36 MIU dayx1) administered. Some patients
`received concurrent systemic rIL-2 or IFA in addition.
`Many significant responses were observed in pulmonary
`metastases, and disease stabilization was seen in over 50%
`patients. The authors concluded that the lack of serious
`toxicities enabled long-term administration of IL-2 (up to
`4 years in some cases) and that disease stabilization was
`associated with prolonged survival.
`
`Combined interleukin-2 and interferon-a
`therapy
`
`the cytokine
`the complexity of
`As stated previously,
`network makes it very difficult to know precisely how one
`cytokine will affect the production of other cytokines.
`Theoretically, several cytokines could enhance the efficacy
`of IL-2, whereas others could be antagonistic. IFA appears
`to be able to activate cytotoxic function by stimulating
`host
`lymphocytes and macrophages, and upregulating
`MHC class I antigen expression on tumour cells, thus
`increasing CTL activity. However, it may also inhibit
`rIL-2-mediated lymphocyte activation [29].
`The first phase II study of subcutaneous rIL-2 plus IFA
`in cancer patients was initiated by Atzpodien & Kirchner
`in the late 80 s [30, 31]. Treatment consisted of a 2 day
`rIL-2 pulse followed by a 5 day rIL-2 schedule for 6 weeks
`in addition to IFA 2–3 times weekly over the same period.
`Doses of rIL-2 were 14.4–18 MIU mx2 dayx1 induction
`pulses, and 3.6–4.8 MIU mx2 dayx1 thereafter. Doses of
`IFA were 3–6 MIU mx2. Of 32 renal cancer patients
`treated,
`four complete responses (CR) and six partial
`responses (PR,>50% reduction in tumour volume) were
`
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`observed, for an overall response rate of 31%. Moreover, a
`further 13 patients had stable disease, and the median
`duration of the complete responses was 19 months. Side-
`effects were graded as mild or moderate in the majority of
`patients, and no deaths due to therapy occurred. This ease
`of
`administration contrasted favourably with bolus
`intravenous administration or rIL-2, and was certainly
`acceptable as out-patient therapy.
`Dutcher and colleagues initiated a corroborative phase
`II study of subcutaneous rIL-2 plus IFA in metastatic renal
`cell cancer in 1992 [32]. Here, a simpler schedule was
`utilized, with comparable doses of both cytokines.
`Treatment consisted of rIL-2 5 MIU mx2 on days 1–5,
`plus IFA 5 MIU mx2 on days 1,3 and 5 with both
`cytokines administered for 4 weeks with a 2 week break.
`Repeated cycles were allowed, and 50 patients were
`treated, of which eight
`(17%)
`responded with two
`complete responses. Response duration was 12 months
`(range 1–56+).
`However, there were concerns that although response
`rates appeared comparable with high-dose intravenous
`bolus treatment, the duration of response appeared to be
`shorter with the lower doses delivered. A randomised
`phase II trial of high dose rIL-2 and high dose rIL-2 plus
`IFA had previously demonstrated that the addition of IFA
`to high dose rIL-2 did not improve efficacy [33]. In
`addition, Clark and coworkers have since reported that
`very low doses of both cytokines (1 MIU mx2 dayx1 for
`12 weeks of both IL-2 and IFA) is ineffective, with no
`responses observed in 19 patients
`selected for
`their
`perceived inability to tolerate intravenous IL-2 [34].
`Perhaps
`the definitive study comparing combined
`cytokine therapy with single cytokine treatment was
`carried out by the Groupe Francais d’Immunotherapie.
`This trial (the ‘CRECY’trial) not only set out to compare
`single agent rIL-2 with the combination of rIL-2 plus IFA
`but also intended to compare both of these treatments with
`IFA alone in a three-way randomization [35]. In this
`multicentre randomised trial, 425 patients were allocated
`treatment with either (i) a continuous intravenous infusion
`regimen of rIL-2 18 MIU mx2 dayx1 (ii) 10 weeks of
`subcutaneous IFA 18 MIU dayx1 three times a week or
`(iii) rIL-2 as in (i) in addition to a reduced dose of IFA, 6
`MIU dayx1 three times a week, for the 10 weeks of
`treatment. Following a response assessment after 10 weeks
`of therapy, patients could receive maintenance therapy or
`cross over to the other cytokine (i.e. groups i and ii).
`Patients receiving rIL-2 were required to have a central
`venous catheter inserted for the duration of
`therapy.
`Efficacy was in favour of the combination arm in that
`response rates for the three arms were (i) 6.5% (ii) 7.5%
`and (iii) 18.6% (P<0.01). In addition, the 1 years event
`free survival for the groups were 15%, 12% and 20%
`(P=0.01). Despite this, the overall survival rates were not
`
`Immunotherapy for renal carcinoma
`
`found to be significantly different for any treatment arm
`(median survival 12, 13 and 17 months, P=0.55). With
`respect
`to tolerability,
`side-effects were seen more
`frequently in the group receiving continuous infusional
`rIL-2.
`
`Chemoimmunotherapy
`
`Despite the low activity generally for chemotherapy in
`renal
`cell carcinoma, preclinical
`synergy has been
`demonstrated
`for
`5-fluorouracil
`(an antimetabolite
`which has been available since the 1950s) and interferon
`[36]. A phase I/II trial of combination chemoimmu-
`notherapy was
`reported in 1995 by Atzpodien and
`colleagues, wherein 24 patients with progressive metastatic
`renal cancer were treated with a regimen containing rIL-2,
`IFA, 5FU, vinblastine and 13-cis-retinoic acid for 8 weeks
`[37]. The doses and schedule are shown in Table 1. This
`pilot study produced an overall response rate of 42%, with
`four complete responses and six partial responses at a
`variety of metastatic sites. Significant cytokine-related
`side-effects were seen in only 4–8% of treatment cycles,
`although 20% of treated patients did develop a peripheral
`neuropathy, likely to be secondary to vinblastine.
`In a subsequent study,
`this group reported a 39%
`response rate in 120 patients receiving only 5-FU in
`combination with rIL-2 and IFA at the same doses as in
`Table 1 [38]. Again, significant efficacy was demonstrated,
`and 13 complete remissions were observed, which were
`durable. The majority of patients had only mild constitu-
`tional symptoms such as fever, chills, and malaise which
`confirmed the suitability of this regimen as an outpatient
`treatment. In another study 78 patients were randomised
`
`Table 1 Chemoimmunotherapy regimens.
`
`(a) Ref [37]
`rIL-2
`
`IFA
`
`5-FU
`Vinblastine
`13-cis retinoid
`(b) Ref [41]
`rIL-2
`
`IFA
`
`5-FU
`(c) Ref [42]
`rIL-2
`IFA
`5-FU
`
`10 MIU mx2 2xday
`5 MIU mx2 2xday
`6 MIU mx2
`6 MIU mx2
`9 MIU mx2
`1g mx2
`6 mg mx2
`35 mg mx2
`
`10 MIU mx2 2xday
`5 MIU mx2 2xday
`6 MIU mx2
`6 MIU mx2
`9 MIU mx2
`750 mg mx2
`
`weeks 1+4
`days 3–5
`days 1,3,5 weeks 2+3
`weeks 1+4
`days 1
`days 1,3,5 weeks 2+3
`days 1,3,5 weeks 5–8
`day 1
`weeks 5–8
`day 1
`weeks 5–8
`day 1–7
`weeks 1–8
`
`weeks 1+4
`day 1
`days 1,3,5 weeks 2+3
`weeks 1+4
`days 3–5
`days 1,3,5 weeks 2+3
`days 1,3,5 weeks 5–8
`day 1
`weeks 5–8
`
`9 MIU
`6 MIU mx2
`600 mg mx2 dayx1 c.i.
`
`weeks 1,3,5,7
`days 1–6
`days 1,3,5 weeks 1,3,5,7
`days 1–5
`weeks 1,5
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`P. A. Vasey
`
`to receive this regimen or oral tamoxifen (an antioestro-
`genic hormone)
`therapy. The response rate for
`the
`chemoimmunotherapy was again 39%, but no objective
`responses were seen in the tamoxifen-treated patients [39].
`As expected,
`survival parameters were significantly
`improved in patients receiving the chemoimmunotherapy
`(median PFS 13 months vs 4 months P<0.01; OS median
`not reached after 42 months vs 14 months).
`Finally,
`this regimen was evaluated further in 246
`patients who received up to 4 consecutive treatment cycles
`unless progression of disease occurred. An overall response
`rate of 33% was observed, with a median survival for the
`group as a whole of 21 months [40].
`These results are among the best reported so far in this
`disease. The ability to deliver
`the treatment as an
`outpatient, thus eliminating the need for hospital admis-
`sion and/or intensive care demonstrates an improved
`therapeutic index and additionally, cost-effectiveness.
`However, other centres have not been able to reproduce
`these results, and it is possible that a major selection bias for
`this particular patient population may be partly respon-
`sible. Dutcher and colleagues, for the Cytokine Working
`Group (CWG) treated 50 patients with a similar regimen
`to that of Atzpodien, albeit with slightly lower doses of
`rIL-2 and 5-FU (Table 1, [41]). Here, the overall response
`rate was 16% (95% confidence interval 7–27%).
`In
`addition, Negrier et al. randomised 131 patients to receive
`either an 8 week regimen of rIL-2 and IFA, or the same
`regimen with 5-FU delivered by continuous intravenous
`infusion on days 1–5 for week 1 and 5 (Table 1, [42]). The
`incidence and severity of side-effects reported in both arms
`was similar, but response rates were low, occurring in only
`1.4% of patients receiving the cytokines, and 8.2% of
`patients receiving the cytokine/5-FU combination. The
`difference in efficacy was not significant, but suggested
`that this particular dose and schedule is of little therapeutic
`value.
`
`Experimental approaches
`
`Studies have demonstrated that a subset of peripheral
`blood lymphocytes, natural-killer (NK) cells, can be
`activated ex vivo by rIL-2 [43]. This approach, termed
`‘adoptive immunotherapy’ was found to enhance the in
`vitro cytotoxicity of these cells, now called ‘lymphokine-
`activated killer’ (LAK) cells. In subsequent NCI-sponsored
`clinical studies, significant activity was observed in patients
`with a variety of malignancies, but the high doses of rIL-2
`used resulted in significant toxicity [44].
`A variation of
`this approach involves harvesting
`lymphocytes which infiltrate tumour biopsies
`(TILs),
`and expanding them ex vivo by exposure to rIL-2 [45]. As
`TILs are T-lymphocytes which express both CD4 and
`CD8 T-cell markers, they are potentially specific against
`
`tumour antigens. Preclinical work has demonstrated
`increased potency compared with LAK cells, and early
`clinical trials have reported activity which is potentially
`superior to rIL-2 alone [46]. Randomised trials comparing
`this approach with rIL-2 are ongoing in the USA.
`Autolymphocyte therapy involves the use of ex vivo
`expanded leucocytes which have been activated by rIL-2
`and anti-CD3 monoclonal-antibody-activated autologous
`peripheral blood lymphocytes. Anti-CD3 is thought to
`activate antigen-exposed (memory) T-cells. Clinical trials
`have been performed where the cells are treated with
`cimetidine and irradiated to destroy suppressor T cells
`prior
`to infusion [47].
`In this
`small
`(90 patients)
`randomised trial, patients receiving the ex vivo activated
`cells had a significant survival advantage compared with
`those receiving high dose cimetidine only.
`Even newer approaches
`involve the utilization of
`dendritic cells in an attempt to augment the immune
`response. These cells are the most prolific antigen-
`presenting cells in humans, express class II MHC, and
`produce a variety of cytokines including IL-12 and IFA.
`Both these cytokines stimulate TH cells, and therefore
`contribute to the immune response. Strategies being
`investigated include the adoptive transfer of
`tumour
`antigen-pulsed dendritic cells to elicit an antigen-specific
`(largely cell-mediated) response to tumour cells. This
`approach has successfully induced immune responses in a
`number of murine models, and clinical trials are underway
`(reviewed in [48]). Similarly, the role of IL-12 in the
`development of the cellular immune response and its
`potential as an antitumour agent
`is being actively
`investigated.
`
`Conclusions
`
`There is no internationally recognized standard therapy for
`metastatic renal cancer, and patients are treated with IFA
`or rIL-2 monotherapy, or combinations outside of clinical
`trials. Until better treatments are available, the aim of
`systemic therapy is to extend survival without negatively
`impacting on the quality of
`life, and it
`is
`therefore
`appropriate to try and identify patient factors which can
`predict for long survival times and/or responsiveness to
`immune therapies. Factors identified from retrospective
`studies as predictors of overall survival include perfor-
`mance status, presence or absence of liver disease and
`number of metastatic sites [49, 50]. Negrier and colleagues
`calculated that patients with multiple metastatic sites, liver
`disease, or more than 1 year from the time of diagnosis to
`the development of metastases, had a 70% chance of rapid
`progression despite immunotherapy, with a median overall
`survival of only 6 months [35]. It is therefore sensible to
`select patients
`carefully prior
`to the initiation of
`immunotherapy. Such a selection procedure should pay
`
`526
`
`f 2000 Blackwell Science Ltd Br J Clin Pharmacol, 50, 521–529
`
`NOVARTIS EXHIBIT 2012
`Breckenridge v. Novartis, IPR 2017-01592
`Page 6 of 9
`
`

`

`particular reference to: (a) performance status, (b) the
`disease-free interval, (c) favourable (lungs) or unfavourable
`metastatic sites (central nervous system/bone/liver) and (d)
`overall tumour burden (e) number of metastatic sites.
`What therapy to use depends upon the local availability
`of particular cytokines, and the cost allocated to these
`expensive agents by individual Health Boards. In Glasgow,
`monotherapy with IFA is the treatment of choice, and is
`preferred over rIL-2 because of the absence of comparative
`data showing inferiority when both are given subcuta-
`neously. IFA certainly has a favourable cost and toxicity
`differential over rIL-2 when the latter is given by repeated
`bolus intravenous injection.
`In contrast, most USA cancer centres base their
`treatments around subcutaneous rIL-2, either as mono-
`therapy or as combinations with IFA despite the concerns
`that the delivery of low dose rIL-2 by the subcutaneous
`route is not as effective as
`the much more toxic
`intravenous
`regimen.
`In addition, an advantage for
`combination therapy over monotherapy is not proven as
`evidenced by the CRECY trial
`(which utilized an
`intravenous
`rIL-2/subcutaneous
`IFA combination).
`Further randomised trials are clearly necessary, and the
`MRC is proposing a national UK trial which will compare
`the Atzpodien combination of IFA, rIL-2 and 5FU with
`single agent IFA. This study should start recruitment this
`year.
`Many clinical researchers, particularly in the USA, use
`the subcutaneous combination of IFA and rIL-2 as the
`‘backbone’ to which novel agents including chemotherapy
`and other cytokines are added. The addition of 5-FU to
`IFA and rIL-2 as per the Atzpodien regimen has shown
`remarkable efficacy, although these results have yet to be
`confirmed by other investigators. However, this combina-
`tion of chemotherapy and cytokines is currently being
`used as the treatment arm in a multicentre, European study
`of adjuvant treatment vs no treatment for patients at high
`risk of
`relapse following nephrectomy. This
`trial
`is
`currently being co-ordinated through the CRC Depart-
`ment of Medical Oncology in Glasgow.
`New approaches are needed to take the treatment of
`metastatic renal cell cancer forward. The EORTC are
`pursuing a randomised trial of IFA in combination with
`13-cis retinoic acid, a natural metabolite of vitamin A
`which has anticancer activity through a number of
`mechanisms
`including antiangiogenesis, differentiation
`induction and inhibition of IL-6. There are a number of
`preclinical
`studies which suggest
`that
`simultaneous
`exposure to both interferons and retinoids can result in
`enhanced antiproliferative and differentiation effects,
`compared with either agent alone [51]. Also, there is
`evidence of an interaction at the molecular level which
`may be synergistic. SRL 172 (SR Pharma, London), a
`heat-killed suspension of Mycobacterium vaccae, expresses
`
`Immunotherapy for renal carcinoma
`
`heat shock proteins which are thought to be involved in
`the presentation of
`tumour
`antigens. Furthermore,
`following exposure to this agent,
`sustained cytokine
`responses have been demonstrated, with increased cellular
`expression of IL-2, IFA and interferon-c (Investigators
`brochure, SRL 172, SR Pharma, UK). Trials are ongoing
`in renal cell cancer and other cell types, but preliminary
`experience suggests that it is better tolerated than IFA.
`Improved tolerance to immunotherapy is an ongoing
`objective of research, and nonrandomised data suggest that
`the concomitant use of corticosteroids can abrogate some
`of the toxicities associated with IFA. However, there are
`theoretical risks of a negative interaction between steroids
`(which have immunosuppressive properties) and IFA,
`although nonrandomised data do not
`support
`this.
`Definitive evidence would only be produced by a
`prospective, randomised study. Also, pegylated constructs
`IFA have been produced (e.g. PEG IntronTM,
`of
`Schering-Plough; Ro 25–8310, Hoffman-La Roche),
`and early clinical trials seem to indicate that patients
`may be able to to