Fever and the use of paracetamol during IL-2-based immunotherapy in metastatic melanoma

Abstract

Fever is frequently observed in conjunction with interleukin-2 (IL-2)-based immunotherapy. Traditionally, fever has been regarded as an undesirable side effect and treated with fever-lowering drugs. However, new insights in tumor immunology suggest that elevated temperature may facilitate a more effective antitumor immune response. The purpose of this retrospective study was to examine the potential role of the IL-2-induced fever in melanoma patients treated with or without paracetamol in two consecutive cohorts. One hundred and seventy-nine patients with metastatic melanoma treated with a modified decrescendo regimen of IL-2 and Interferon (IFN) between 2004 and 2010 were retrospectively studied. 87 patients treated before 2007 received paracetamol as part of the treatment schedule, and 92 patients treated after 2007 did not receive paracetamol routinely. Body temperature was analyzed as dichotomized and continuous variables and correlated to objective tumor response and overall survival using logistic regression and Cox proportional hazard analysis. Patients experiencing peak temperature of ≥39.5 °C had a median OS of 15.2 months compared to 8.7 months among patients with lower temperatures (P = 0.01). In the multivariate analysis, peak temperature of ≥39.5 °C (HR 0.53; P = 0.026) and high mean temperature (HR 0.56; P = 0.004) were independent prognostic factors for improved survival. We suggest high fever as a biomarker for improved survival in melanoma patients treated with IL-2/IFN. The routine use of fever-reducing drugs during immunotherapy can therefore be questioned. More studies are needed to evaluate the role of fever and the use of antipyretics during cytokine-based immunotherapy.

Background

Since the mid-1970s, melanoma incidence rates have increased more rapidly than any of the ten most common cancers worldwide [1, 2]. Despite significant progress in the treatment of advanced melanoma, including the approval of ipilimumab [3] and vemurafenib [4] and promising agents in late stage clinical trials [5], metastatic melanoma remains a clinical challenge.

Immunotherapy with IL-2 and combinations with Interferon-alpha has been used in the treatment of metastatic melanoma for nearly three decades now [6]. Although response rates are modest, high-dose IL-2 has a curative potential with the induction of durable complete responses in 5–8 % of the patients [6].

Toxicities associated with IL-2 treatment are highly dose dependent and may be severe [7]. Traditionally, fever and flu-like symptoms have been considered simple side effects to IL-2 therapy, and fever-lowering drugs have been used routinely to make the treatment more tolerable.

However, accumulating evidence suggests that fever may have beneficial effects on immune functions [8–12]. Recent studies have shown a proliferation of T and natural killer (NK) cells as well as an enhancement of the cytotoxicity of effector T cells and stimulatory effects of dendritic cells (DCs) following fever range temperatures [13–16]. This improved understanding of immune functions and host defense, supported by observations in the clinic, led to the hypothesis that fever may facilitate a more effective antitumor immune response.

Consequently, we became interested in the possibility that the IL-2-induced fever was a beneficial side effect to IL-2/IFN. In 2007, we stopped the routine use of fever-lowering drugs in patients with metastatic melanoma undergoing IL-2-based immunotherapy.

Due to its safety profile, paracetamol (acetaminophen) is one of the most commonly used antipyretic and analgesic drugs [17]. Its mechanism of action has been debated, but is generally considered to be a central inhibition of prostaglandin synthesis and activation of descending serotonergic pathways. Unlike non-steroidal analgesic inhibitory drugs (NSAIDs), paracetamol has relatively little anti-inflammatory and no anti-thrombotic activity [17]. The recommended therapeutic dose of paracetamol is 1 g four times daily, which was the standard dose used routinely in this study.

The purpose of this retrospective study was to examine the prognostic role of the IL-2-induced fever in patients treated with or without paracetamol in two consecutive cohorts.

Methods

One hundred and seventy-nine patients with stage IV melanoma treated with standard first-line IL-2 and IFN between January 2004 and January 2010 were retrospectively studied. In general, patients received treatment with IL-2/IFN if they were under the age of 70, WHO performance status (PS) 0–2, without significant comorbidity and without symptomatic brain metastases. Only patients with measurable tumor lesions according to the response criteria for solid tumors (RECIST) were included in this retrospective study.

IL-2/IFN was administered as a modified decrescendo regimen consisting of 3-week cycles starting with Pegylated Interferon 300 µg on day 1 in the first week. From day 8 in the second week, IL-2 was administered as a continuous infusion starting with 18 MU/m² for 6 h, followed by 18 MU/m² for 12 h, followed by 18 MU/m² for 24 h and finally 4.5 MU/m² in 24 h for 3 days. In the third week, no treatment was administered.

Patients treated with IL-2/IFN between 2004 and 2007 received paracetamol at a dose of 1 g four times per day during the first and second treatment weeks. Patients treated after 2007 did not routinely receive paracetamol or other antipyretics, except in cases of body temperature exceeding 41 °C or of other patient-specific reasons such as severe headache or other pain. As this was a retrospective analysis, seven patients treated after 2007 who had received more than 20 g of paracetamol distributed over one treatment cycle were included in the cohort of paracetamol-receiving patients treated before 2007.

Information on patient and disease characteristics, treatment toxicity and laboratory tests were collected from medical records and registered in a database. Body temperature was measured every 8 h during each cycle of IL-2, resulting in 16 measurements per cycle. Treatment efficacy was evaluated using a computed tomography (CT) scan of the chest, abdomen and pelvic region at baseline, after every second cycle of IL-2/IFN and every 12 weeks during follow-up. Tumor response was determined according to RECIST version 1.0.

Patients with complete or partial response after two cycles continued treatment with two or in selected cases four more cycles of immunotherapy. Patients with stable disease and acceptable toxicity after two cycles were allowed two more cycles.

Body temperature was scored and analyzed in two ways. First, as a dichotomized variable using 38.5, 39.5 and 40 °C as cut points for the peak temperature in each cycle. The cut point of 39.5 was used for further analyses, as this was the median temperature for the whole cohort of patients and because too few patients had experienced temperatures below 38.5 or above 40 °C for the use in a dichotomized analysis. Second, as an estimate of mean temperature, body temperature was analyzed as a continuous variable, by calculating the normalized area under the temperature curve (AUC) during treatment cycles 1 and 2.

Body temperature was then correlated to objective tumor response and overall survival using logistic regression and Cox proportional hazard analysis. Data on survival and relapse were updated on January 2012. Survival probabilities were estimated using the Kaplan–Meier method and strata compared using the Wilcoxon test and log rank statistics. Model assessment of linearity and proportional hazards was done using Martingale and Schoenfeld residuals. STATA software (v 1.0) or SAS (v 9.2, SAS Institute, Cary, NC, USA) was used for all analyses. The level of statistical significance was 5 %, reported with 95 % confidence intervals (CI).

Results

Patient characteristics

One hundred and seventy-nine patients with stage IV melanoma were treated with IL-2/IFN between 2004 and 2010. Eighty-seven patients (48 %) had received paracetamol routinely and 92 had not.

Median age at baseline was 58, ranging from 17 to 73, with the majority of patients (67 %) being in PS 0. More than half of the patients (54 %) presented with stage M1c disease [visceral metastases other than lung or any metastases combined with elevated serum lactate dehydrogenase (LDH)] at baseline. Significantly, more patients in the paracetamol-treated cohort had elevated neutrophil count at baseline compared with the cohort of patients treated without paracetamol. Elevated neutrophils have previously been shown to be an independent prognostic factor for poor overall survival in patients with metastatic melanoma receiving IL-2-based immunotherapy [18].

Other patient characteristics did not differ significantly between the two cohorts (Table 1).

Table 1.

Distribution of patient demographics in patients treated with IL-2/IFN with or without paracetamol

Characteristic	Paracetamol cohort N = 87 (%)	No paracetamol cohort N = 92 (%)	P value
Sex
Male	40 (46)	36 (40)	0.387
Female	47 (54)	55 (60)
Age
Median (range)	53 (27–63)	61 (17–73)
Performance status
0	53 (61)	67 (74)	0.187
1	32 (37)	23 (25)
2	2 (2)	1 (1)
Baseline LDH
>ULN	52 (60)	45 (50)	0.167
≤ULN	35 (40)	46 (50)
Baseline neutrophil count
>ULN	29 (33)	16 (17)	0.02
≤ULN	58 (67)	75 (82)
Site of metastasis
Skin, lymph nodes	7 (8)	10 (9)	0.542
Lung	5 (6)	10 (9)	0.208
Other viscera	75 (86)	71 (77)	0.155
Number of metastatic sites
1	12 (14)	15 (16)	0.809
2	33 (38)	36 (40)
≥2	42 (48)	40 (44)

Treatment outcome

The median follow-up time (time to end of study) for all patients was 5.2 years (range 3–8 years). Patients receiving paracetamol, treated between 2004 and 2007, had significantly longer follow-up time compared with patients treated after 2007, not receiving paracetamol (6.5 vs. 3.9 years, P < 0.001). One hundred and seventy patients (95 %) completed at least two cycles of immunotherapy, and almost half of the patients (48 %) received at least four cycles with six patients receiving six cycles of IL-2/IFN.

Median temperature during IL-2 infusions among patients treated with paracetamol was 38.1 °C compared with 38.6 °C among patients treated without paracetamol (P < 0.001). The analysis of body temperature as a function of time showed a significant decrease in both peak and mean temperatures (P = 0.039 and P = 0.019, respectively) comparing the first and the second cycle of IL-2, regardless of paracetamol intake.

Median overall survival (OS) for all patients was 11.2 months [95 % confidence interval (CI) 8.51–12.19]. Patients with a peak temperature of ≥39.5 °C during the first cycle of IL-2 had a median OS of 12.1 months (95 % CI 8.7–15.2) compared with 8.9 months (95 % CI 7.1–11.9) in patients with lower peak temperature. HR for death was 0.70 (95 % CI 0.52–0.96, P = 0.025) in favor of high temperature (Fig. 1). When analyzing the temperature as a continuous variable (the normalized area under the temperature curve, AUC), we found a statistical significant HR of 0.73 (P = 0.018) for cycle 1 and 0.66 (P = 0.006) for cycle 2.

Fig. 1.

Kaplan–Meier curve of overall survival stratified for body temperature ±39.5 °C. HR for death was 0.70 (P = 0.025) in favor of peak temperature ≥39.5 °C. Blue line = body temperature ≥39.5 °C, yellow line = body temperature <39.5 °C

Because there was a significant interaction between paracetamol intake and body temperature, the survival analysis was performed, stratifying for paracetamol. This analysis showed that patients not receiving paracetamol, achieving temperature of 39.5 °C or above, had a significant superior survival of median 15.2 months (95 % CI 11.4–18.2) compared with 8.7 months (95 % CI 5.8–19.8) in patients with lower temperatures (P = 0.048) (Fig. 2). In the cohort of patients receiving paracetamol, there was no association between body temperature and OS (HR 0.99, P = 0.98).

Fig. 2.

Kaplan–Meier curve of overall survival and body temperature ±39.5 °C stratified for the use of Paracetamol. Blue line = patients not receiving paracetamol with peak temperature of ≥39.5 °C, green line = patients receiving paracetamol with peak temperature <39.5 °C, pink line = patients receiving paracetamol with peak temperature of ≥39.5 °C, yellow line = patients not receiving paracetamol with peak temperature <39.5 °C

In the multivariate analysis, peak temperature of 39.5 °C or above (HR 0.53, 95 % CI 0.32–0.87, P = 0.026) as well as high mean temperature (HR 0.56, 95 % CI 0.37–0.85, P = 0.004) were independent factors for improved survival (Table 2). Additionally, elevated baseline neutrophil count (HR 2.28, 95 %CI 1.56–3.33, P ≤ 0.005) and serum LDH level (HR 1.61, 95 % CI 1.16–2.23, P ≤ 0.005) were independent negative prognostic factors.

Table 2.

Multivariate Cox regression analysis of overall survival

Predictor	HR	95 % CI	P value
Peak tempa + paracetamol	1.14	0.71–1.84	0.029
Peak tempa − paracetamol	0.53	0.32–0.87
Mean tempb + paracetamol	1.31	0.86–1.98	0.004
Mean tempb − paracetamol	0.56	0.37–0.85
LDH >ULN versus <ULN	1.61	1.16–2.23	0.004
Neutrophils >ULN versus <ULN	2.28	1.56–3.33	<0.0001
Performance status	1.26	0.89–1.80	0.20
No. metastatic sites	1.54	0.97–2.44	0.07

HR hazard ratio, LDH lactate dehydrogenase, ULN upper limit of normal

^aPeak temperature ≥39.5 °C, ^b mean temperature, normalized area under the curve (AUC)

Three patients (1.7 %) achieved a complete response (CR), 12 patients (6.7 %) had a partial response (PR), and 55 patients (30.7 %) had stable disease (SD), accounting for a response rate of 8.4 % and a disease control rate of 39 %. There were significantly more responders in the group of patients treated without paracetamol compared with patients receiving paracetamol (14 vs. 2 %, P = 0.004). Still, there was no statistically significant association between body temperature and objective tumor response. However, when looking at patients surviving more than 2 years, there were significantly more responders in the group of patients not receiving paracetamol (25 %) compared with the paracetamol-treated patients (10 %, P = 0.01). Additionally, the proportion of patients surviving more than 2 years reaching a peak temperature of ≥39.5 °C was significantly higher in the group treated without paracetamol (P = 0.035). In patients surviving more than 2 years, four (one in the paracetamol group and three in the non-paracetamol group) had later received second-line therapy with ipilimumab. None of the patients had received treatment with vemurafenib or other agents at the time of the update.

Toxicity

Table 3 shows the IL-2/IFN-related toxicity among patients treated with or without paracetamol. Grade 1 and 2 pruritus was more frequently reported in patients treated without paracetamol, whereas grade 3 or 4 was more frequent in patients receiving paracetamol. The most severe adverse event was grade 3 or 4 capillary leak syndrome, which was reported in 20 % of the patients in both cohorts.

Table 3.

Toxicity in patients treated with IL-2/IFN with or without paracetamol

Adverse event	Paracetamol cohort N = 87	No paracetamol cohort N = 91	P value
Nausea
Any grade	65	63	0.416
Grade ¾	2	0	0.003
Pruritus
Any grade	51	34	0.004
Grade ¾	4	1	0.006
Diarrhea
Any grade	38	41	0.853
Grade ¾	2	1	0.613
CNS
Any grade	8	7	0.718
Grade ¾	0	3	0.005
Capillary leak syndrome
Any grade	26	21	0.390
Grade ¾	5	7	0.362

Discussion

Fever associated with IL-2-based immunotherapy has generally been regarded as an undesirable side effect and treated with fever-lowering drugs. However, in the present retrospective consecutive study of metastatic melanoma patients treated with IL-2/IFN with or without the routine use of paracetamol, we observed that peak temperature of at least 39.5 °C and high mean temperature were independent prognostic factors for improved survival. Consistent with previous findings, elevated neutrophil count and serum LDH levels were prognostic for a poor survival [18, 19].

The proposed mechanism of the IL-2-induced fever involves the activation of secondary cytokines. Following treatment with IL-2 pro-inflammatory cytokines like IL-1, IFN-gamma and TNF-alpha can be detected in peripheral blood [20, 21]. In particular, the prompt release of TNF-alpha, which is a strong intrinsic pyrogen causing fever through its direct interaction with the hypothalamus, is considered a key contributor to the IL-2-associated fever [21]. However, the systemic use of TNF-alpha as a single agent has not been successful, primarily due to considerable toxicity but also limited antitumor efficacy. Combined with other drugs in the setting of hyperthermic isolated limb, though, this cytokine is used with therapeutic benefit [22].

The high fever associated with improved survival among the IL-2-treated patients may be a biomarker for a more efficient immune-mediated antitumor response. Having fever is a part of an effective immune response, and accumulating evidence exists that immune function is temporarily enhanced when the temperature rises with fever [12, 15]. Fever plays a vital role in the innate immune response and exerts pleiotropic immune-stimulating effects [8, 23]. Recent preclinical studies have demonstrated that fever range temperatures may induce T cell proliferation and differentiation [15]. Following mild hyperthermia, the cytotoxicity of neutrophils and effector CD8+ T cells have been shown to be enhanced both in vivo and in vitro as well as the immune stimulatory effects of DCs seem to be improved in terms of increased antigen uptake and T cell stimulation [9, 13, 15, 16]. Endogenous fever also induces the production of pro-inflammatory cytokines such as IL-1, IL-6, IFN and TNF-alpha [9, 10, 13]. Furthermore, there is the aspect of heat. Like bacteria, tumor cells are more susceptible to heat than normal cells as they undergo necrosis at lower temperatures [9, 12].

Other groups have investigated the impact of fever-reducing drugs such as indomethacin and ibuprofen on immune response parameters and objective tumor response during IL-2 treatment, without finding a significant association [24, 25]. However, the relationship between body temperature and survival was not addressed in these studies. To the best of our knowledge, the routine use of paracetamol in the setting of IL-2-based immunotherapy has not been investigated previously.

The role and value of fever, though, have been elucidated in several historical as well as newer publications [10, 16, 26]. The work by Dr. William Coley (1862–1936), who believed that acute infections could induce tumor remission, is maybe the most comprehensive [27]. First with live bacteria, later changed to a heat killed bacterial vaccine, Coley treated more than 1,000 patients with different advanced cancers and achieved an astonishing 5-year survival rate of 44 % [10]. Coley regarded the vaccine-induced fever as crucial for an effect of the treatment and dose-escalated the patients until high fever occurred, preferentially in the range of 38.8–40 °C [28].

In the present retrospective study, we analyzed the impact of temperature by looking at the peak and mean temperatures achieved during IL-2 infusion. Using these two approaches, we found a strong positive prognostic effect of high fever. However, when stratifying for the use of paracetamol, the association between high fever and improved survival was present only in patients treated without paracetamol, but could not be found among patients receiving paracetamol routinely. This might be explained by significantly lower body temperatures among the paracetamol-treated patients compared with the patients not receiving paracetamol, suggesting that there is a threshold value for the temperature to become beneficial on patient outcome. However, based on this analysis, it cannot be ruled out that it is the use of paracetamol that impairs antitumor immunity and actually has greater impact on patient survival than the body temperature itself. More studies are needed to further clarify this.

In this study, we evaluated the temperature development over time. We found that both peak and mean temperatures significantly decreased with successive IL-2 cycles. This may reflect a progressive immune tolerance to the treatment. Inspired by Coley’s approach, one could speculate whether a dose escalation to restore high temperatures could improve the efficacy of the ongoing immunotherapy.

In contrast to what has been reported previously, our data show that within the upper limit of 41 °C, eliminating paracetamol during IL-2 treatment does not make the treatment significantly more toxic. Instead, it is our impression that patients seem more comfortable having a constant fever rather than fluctuating body temperatures causing chills, shivering and sweating, which often is the case with the use of paracetamol.

The present study is associated with several limitations due to it being a retrospective non-randomized study and the fact that the two cohorts of patients were treated at different time points. The results can therefore only be regarded as hypotheses generating.

Still, we observed a strong and consistent association between high body temperature and overall survival. However, we were unable to demonstrate a significant association between body temperature and objective tumor response. We attribute this finding to the fact that only 15 out of the 176 patients had a radiologically verified complete or partial tumor response. Nevertheless, significantly more responders and long-term survivors were identified among patients treated without paracetamol than among those receiving paracetamol.

In conclusion, we suggest high fever as a biomarker for improved survival in patients with metastatic melanoma treated with IL-2/IFN. Based on these data, we have stopped the routine use of paracetamol to patients with melanoma and renal cell carcinoma treated with IL-2/IFN. Attempts to validate our findings are underway in a prospective phase II trial of IL-2-based immunotherapy in patients with metastatic renal cell carcinoma. Additional studies are needed to further investigate the role of fever in immunotherapy and evaluate fever as possible adjuvant improving antitumor efficacy of cytokine-based immunotherapy.

Abbreviations

AUC

Area under the curve

CI

Confidence interval

CR

Complete response

CT

Computed tomography

DC

Dendritic cells

HR

Hazard ratio

IFN

Interferon alpha

IL-2

Interleukin-2

LDH

Lactate dehydrogenase

MU

Million units

NK

Natural killer cells

NSAIDs

Non-steroidal anti-inflammatory drugs

OS

Overall survival

PR

Partial response

PS

WHO performance status

RECIST

Response criteria for solid tumors

SD

Stable disease