1.1 Adrenal pheochromocytoma/paraganglioma pheochromocytoma (PCC) and Paraganglioma (PGL)
(pheochromocytoma and paraganglioma (PPGL) are rare malignant tumors with neuroendocrine
function and metastatic potential. The incidence is 0.4-2.1 persons/million, 80%-85%
originate from the adrenal medulla, and 15%-20% originate from the neural crest tissue
from the neck to the pelvis. The PPGL metastasis rate at initial diagnosis is 10%, and
the risk of metastasis is as high as 34-69% for those with SDHB gene mutations. The
recurrence rate of PPGL patients after radical resection was 30%, 47% recurred with
multiple nodules, 58% with metastasis. The most common sites of metastasis were lymph
nodes and bone (70-80%), followed by lung and liver (50%). In addition, some PPGL is
difficult/unresectable due to its proximity to important structures such as large blood
vessels or nerves, and the 5-year survival rate for advanced PPGL is 30%-60%.
Early PPGL can be cured by surgery, but late PPGL is mainly systemic therapy, such as
chemotherapy, targeted drugs and nuclide therapy. The main chemotherapy regimen for
advanced PPGL is cyclophosphamide
- - vincristine - dacarbazine (CVD regimen), and ESMO
guidelines recommend CVD for patients with rapid tumor progression and heavy tumor
burden.
The objective response rate of CVD regimen was 33%, the median duration of
response was 1.3 years, and the 5-year survival rate of patients with effective CVD was
51%. The main limitations of CVD in the treatment of advanced PPGL are
- (1) The average
number of cycles required for CVD chemotherapy is 11.6±10.8 months; (2) The incidence of
CVD related toxicity, such as bone marrow suppression and neurotoxicity, was 50%.
Some
patients could not maintain treatment due to intolerance, and long-term use of the above
drugs could increase the incidence of hematological tumors, which may be related to the
alkylating properties of daparbazine.
Domestic guidelines and the FDA recommend 131I-MIBG for the treatment of advanced PPGL.
Loh et al. reviewed and analyzed 21 central LSA-131I-MIBG clinical studies: 30% patients
could have Partial Response (PR); Gonias S et al. Phase II clinical study of
HSA-131I-MIBG in the treatment of advanced PPGL: 22% of patients could have PR. Two
131I-MIBGs show good efficacy, but there are no phase III clinical studies to further
validate efficacy and safety. Limitations of radionuclide therapy lie in
- (1) the narrow
range of indications: (1) ESMO guidelines indicate that only 50% of patients with
positive MIBG scan are suitable.
② Pregnant women and pregnant patients should not use;
- (2) Severe hematological toxicity: the incidence of myosuppression was 4%-79%, about 40%
of patients treated with low-dose 131I-MIBG had grade 3/4 toxicity, while those treated
with high-dose 131I-MIBG had up to 80%, of which 25% needed hematological therapy and
secondary hematological tumors could be developed .
In addition, at
present, the units that can carry out nuclide therapy in China are limited, and patients
can not perform nuclide therapy again after receiving progress of nuclide therapy.
1.2 Tyrosine kinase inhibitors (TKI) and advanced adrenal pheochromocytoma/paraganglioma
Tyrosine kinase (TK) is a key site in the activation and regulation of cell proliferation
signaling pathways. Abnormal TK pathway caused by mutation, translocation or
amplification can lead to tumor occurrence, progression, invasion and metastasis.
Tyrosine kinase inhibitors (TKI) mainly act on vascular endothelial growth factor
receptor (VEGFR), platelet growth factor (PDGFR) and insulin family receptor (InsR). TKI
acts on advanced PPGL through the pseudo-hypoxia pathway and VEGF angiogenesis pathway.
Advanced PPGL with abundant blood supply and high expression of angiogenic factor (VEGF)
can promote tumor neovascularization and provide oxygen and nutrition for tumors. TKI has
a good therapeutic effect on advanced PPGL with high VEGF expression, which may be
related to its blocking of VEGF signaling pathway, continuous inhibition of tumor
neovascugenesis and promotion of abnormal blood vessel normalization. In addition, HIF
axis misalignment can also promote the development and transfer of PPGL. SDH gene
mutations are the most common in PPGL (including SDHA, SDHB, SDHC, SDHD), which cause
abnormalities in the subunit encoding the succinate dehydrogenase complex (SDH) and block
the tricarboxylic acid cycle (TCA). Abnormal TCA can inhibit hypoxia-inducing factor
(HIF-α) proline hydroxylase, and HIF-α accumulation will activate the pseudo-hypoxia
pathway and up-regulate the expression of VEGF and other factors.
ESMO guidelines recommend sunitinib for the treatment of advanced PPGL. Currently, the
only prospective phase II clinical study showed that 3 cases (13%) had PR (SDHB, SDHD,
RET gene mutations, respectively). A retrospective study of 17 cases of advanced PPGL
treated by MD Anderson and Gustavvy-Roussy et al. showed that there were 3 cases of PR
and 5 cases of SD (6 of which were SDHB or VHL gene mutations). In the study , grade 1-2
toxicity was the most common, with about 68% of patients presenting symptoms such as
fatigue, nausea and vomiting, palm-plantar dyspepsia, etc., while only 56%/12% of
patients presented 3/4 toxicity, mainly manifested as nausea, vomiting and hypertension,
without hematological toxicity.
Retrospective studies have also shown that Renvastinib, pazopanib, acitinib and other TKI
have certain efficacy in advanced PPGL, but there is a lack of prospective clinical
evidence. Hassan Nelson L et al. treated 11 cases of advanced PPGL with lenvatinib, and
the results were 5 cases PR, 3 cases SD, and the median PFS was 14.7 months. Mauricio
Emmanuel Burotto Pichun et al. are conducting a study on the treatment of 11 cases of
advanced PPGL with acitinib: 4 cases of PR and 6 cases of SD. The above studies show the
preliminary efficacy of various TKI, and the effect may be better for SDHB mutations,
with a controllable safety, mainly hypertension. In 2017, preliminary results of a
prospective clinical study of cabotinib in the treatment of advanced PPGL were reported
in the conference abstract: ORR of 45%, PFS of 11 months, and no grade 3/4 toxicity. In
summary, TKI monotherapy in the treatment of advanced PPGL shows some effect, but it is
still not satisfactory.
There is currently no standard first-line treatment for advanced PPGL. NCCN guidelines
and China's expert consensus (2020 edition) recommend the use of tumor reduction surgery
(palliative resection) combined with radiotherapy, radionuclide therapy or systemic
chemotherapy and other treatment options, but the above methods have uncertain efficacy
and certain limitations, still need to be confirmed by prospective experiments, so
patients are recommended to participate in clinical trials.
1.3 Application of antirotinib hydrochloride in advanced adrenal
pheochromocytoma/paraganglioma Allotinib (AL3818) is manufactured by Zhengda Tianqing
Pharmaceutical Group Co., LTD. (CTTQ; Lianyungang, Jiangsu, China) self-developed TKI
drugs, targeting VEGFR1-3, FGFR1-4, PDGFRα, G, β, rearrangement (RET) and stem cell
factor receptor (c-Kit) during transfection [26]; Anlotinib has shown good anticancer
activity in vitro/in vitro [27]. A multicentre, randomized, controlled Phase II clinical
study of anlotinib in first-line treatment of metastatic renal cell carcinoma (mRCC)
(NCT02072031)[28] showed similar efficacy of anlotinib and Sunitinib: There were no
significant differences in median PFS (17.May vs.#46; 16.June, P > 0.05), OS, ORR and DCR (P
> 0.05), but the toxicity of anrotinib was lower, and the incidence of ≥3/4 toxicity was
significantly lower than that of Sunitinib (28.9% vs.#46;55.8%, P < 0.01). The main symptoms
were hypertension and hand-foot syndrome, and no hematological toxicity was found. In
addition, Lin J et al. also confirmed that anlotinib and Sunitinib had similar efficacy
but higher safety. TKI treatment of advanced PPGL has a similar mechanism of action, but
anlotinib safety may be better. In addition, our team has a certain foundation in the
study of anrotinib in the treatment of advanced PPGL. In the early stage, anrotinib
monotherapy was used to treat advanced PPGL in 4 cases and PR in 2 cases (1 case was a
SHDB mutation), and the adverse reactions were mostly grade 1-2, with hypertension and
hand-foot syndrome as the main manifestations. Therefore, antirotinib may have better
efficacy and safety in advanced PPGL, which is worthy of further clinical exploration.
1.4 Application of peamprizumab in advanced adrenal pheochromocytoma/paraganglioma
PD-1/PD-L1 monoclonal antibody kills tumors by activating its own normal anti-tumor
immune mechanism. In 2014, Pembrolizumab achieved results in melanoma, officially
ushering in the era of global immunotherapy. Subsequently, indications and significant
curative effects were also obtained in multi-tumor species such as non-small cell lung
cancer, gastric cancer and kidney cancer.
PD-L1 is mainly expressed in tumor cells and antigen-presenting cells (APCs), and is
closely related to tumor immune escape [33] : PD-L1 receptor of tumor cell membrane binds
to PD-1 receptor of T cell membrane, which weakens the ability of cytotoxic T lymphocytes
to kill tumor cells. PD-1/PD-L1 mab blocks the above signaling process and
restores/activates the anti-tumor activity of T cells.
A study in Peking Union Medical College Hospital [35] showed that 59.7% were positive for
PPGL PD-L1 expression (HIS>10), and the positive rate of PD-L1 in advanced PPGL was
100%(1/1). Study [36] showed that PD-L1 expression was positive in 4 out of 10 advanced
PPGL cases (40%). Studies indicated that the cytotoxic T lymphocyte infiltration level
was increased in advanced PPGL (P=0.092). Therefore, PD-1 monoclonal antibody may have
some significance in the treatment of advanced PPGL. At present, only A few cases have
been reported in the treatment of advanced PPGL with PD-1 monoclonal antibody. The Phase
II clinical study conducted by Naing A et al. in the treatment of advanced PPGL patients
with pembrolizumab showed that 43% (4 cases) had no progress at 27 weeks (6.75 months).
This suggests that PD-1 monoclonal antibody has a certain effect in the treatment of
advanced PPGL, but PD-1 monotherapy can not meet the clinical needs.
KATO Y et al. proposed that the effective rate of PD-1 monoclonal antibody in the single
treatment of solid tumors was 20%-30%, and the therapeutic effect was not satisfactory.
The study of PD-1 monoclonal antibody combined with TKI in the treatment of liver cancer
suggests that the combination of PD-1 monoclonal antibody can reverse the
immunosuppressor tumor microenvironment in which PD-1 monoclonal antibody is ineffective,
and assist PD-1/PD-L1 monoclonal antibody to activate cytotoxic T lymphocytes. The
efficacy of acitinib combined with PD-1 mab in the second-line treatment of patients with
metastatic renal cancer was significantly higher than that of acitinib (ORR: 33.6% vs.#46;
20.1%, P=0.015) (PFS: 11.7 months vs.#46; 7.5 months, P=0.002).
Piamprilizumab (Anicol) is a new PD-1 monoclonal antibody developed by Zhengda Tianqing
Pharmaceutical Group Co., LTD., which has been approved for Hodgkin's lymphoma (R/R cHL)
and squamous non-small cell lung cancer (NSCLC) indications in China. Pembrolizumab has
achieved significant efficacy in the treatment of classic Hodgkin lymphoma, metastatic
nasopharyngeal carcinoma, gastric/esophageal junction adenocarcinoma and other tumor
species in clinical studies, with ORR of 89.4%, 29.7% and 26.3%, respectively .
Anicol is a humanized IgG1 subtype of PD-1 monoclonal antibody that eliminates Fc
effects. The IgG1 subtype reduces immune escape by eliminating antibody-dependent
cell-mediated cytotoxicity (ADCC), antibody-dependent cell-mediated phagocytosis (ADCP),
and complement-dependent cytotoxicity (CDC). The combination of anil with FcR can reduce
the occurrence of adverse immune reactions , and the incidence of grade 3 and above
toxicities such as immune-associated pneumonia, hepatitis, myocardium, and pancreatitis
is lower than that of sindillizumab, tirellizumab, and triplizumab. Therefore, this study
intends to use anicol combined with anlotinib to explore its efficacy and safety in
advanced PPGL.
1.5 Application of antirotinib combined with PD-1 monoclonal antibody in advanced
pheochromocytoma/paraganglioma The combination of TKI and PD-1 monoclonal antibody is a
research hotspot in the treatment of advanced tumors. Target-free therapy has been widely
used in renal, urothelial, lung, liver and other tumors, and has achieved remarkable
efficacy [46].
Only a few cases of combined treatment for advanced PPGL have been reported at home and
abroad. In Taizhou Hospital of Zhejiang Province in 2022, a patient was treated with
palizumab injection 200 mg(once every 3 weeks) for intravenous immunotherapy, combined
with anrotinib 10 mg orally (once a day, 14 days and 7 days, every 3 weeks for a course
of treatment). The left adrenal mass (9.6cm →8.4cm) and the multiple intrahepatic mass
(up to 9.3cm →8.8cm) were both reduced. In the early stage, our team used anrotinib
combined with PD-1 monoclonal antibody to treat 3 patients, and the efficacy reached PR
66% (2/3), including 1 case with SHDB mutation. This suggests that targeted immunotherapy
for advanced PPGL may have better efficacy.
In an open, multicenter, phase Ib/II clinical study of anlotinib combined with
piamprizumab in the treatment of advanced hepatocellular carcinoma, the ORR was 31% and
the DCR was 82.8%. The median PFS was 8.8 months (95% CI 4.0-12.3 months). 80% were grade
1/2 toxicity, such as elevated AST, elevated ALT, elevated blood bilirubin, etc. Only
19.4% had grade 3/4 toxicity such as hypertension and rash. This is an improvement in
efficacy and a decrease in toxicity compared to the treatment of advanced hepatocellular
carcinoma with altilizumab combined with bevacizumab or carrilizumab combined with
apatinib.
At present, there have been no studies on the combination of targeted drugs and
immunodrugs in the treatment of advanced PPGL at home and abroad. Therefore, this study
will for the first time apply the combination of TKI drugs (antirotinib) and PD-1
monoclonal antibody (Pembrolizumab) to metastatic/unresectable
pheochromocytoma/paraganglioma, so as to explore the efficacy and safety of combined
drugs in the treatment of advanced pheochromocytoma/paraganglioma.